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Sample records for grip force control

  1. ASSESSMENT OF GRIP FORCE CONTROL IN PATIENTS WITH MUSCULAR DYSTROPHY

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    Gregorij Kurillo

    2004-12-01

    Full Text Available Background. The majority of hand functionality tests are based on qualitative assessment which largely depends on the experience of the therapist. Computer-assisted methods can provide more objective and accurate measurements of the grip force and other parameters related to grasping.Methods. We analysed the grip force control in 12 patients with muscular dystrophy using the tracking system developed. The system consists of a grip-measuring device with endobjects assessing the force applied in different grips. The device was used as input to a tracking task where the patient applied the grip force according to the visual feedback from the computer screen. Each patient performed two tasks which consisted of tracking a ramp and sinus target.Results. We analysed the maximal grip force as assessed in the ramp task and the tracking accuracy of the sinus task. The results are compared among five different grips (cylindrical, lateral, palmar, pinch and spherical grip, applied with dominant and non-dominant hand. The results show no significant difference in tracking accuracy between the dominant and non-dominant hand.Conclusions. The results obtained in tracking the ramp target showed that the method could be used for the assessment of the muscle fatigue, providing quantitative information on muscle capacity. The results of the sinus-tracking task showed that the method can evaluate the grip force control in different types of grips, providing information on hand dexterity, muscle activation patterns or tremor.

  2. Deficits of anticipatory grip force control after damage to peripheral and central sensorimotor systems.

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    Hermsdörfer, Joachim; Hagl, Elke; Nowak, Dennis A

    2004-11-01

    Healthy subjects adjust their grip force economically to the weight of a hand-held object. In addition, inertial loads, which arise from arm movements with the grasped object, are anticipated by parallel grip force modulations. Internal forward models have been proposed to predict the consequences of voluntary movements. Anesthesia of the fingers impairs grip force economy but the feedforward character of the grip force/load coupling is preserved. To further analyze the role of sensory input for internal forward models and to characterize the consequences of central nervous system damage for anticipatory grip force control, we measured grip force behavior in neurological patients. We tested a group of stroke patients with varying degrees of impaired fine motor control and sensory loss, a single patient with complete and permanent differentation from all tactile and proprioceptive input, and a group of patients with amyotrophic lateral sclerosis (ALS) that exclusively impairs the motor system without affecting sensory modalities. Increased grip forces were a common finding in all patients. Sensory deficits were a strong but not the only predictor of impaired grip force economy. The feedforward mode of grip force control was typically preserved in the stroke patients despite their central sensory deficits, but was severely disturbed in the patient with peripheral sensory deafferentation and in a minority of stroke patients. Moderate deficits of feedforward control were also obvious in ALS patients. Thus, the function of the internal forward model and the precision of grip force production may depend on a complex anatomical and functional network of sensory and motor structures and their interaction in time and space.

  3. Differences in grip force control between young and late middle-aged adults.

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    Zheng, Lianrong; Li, Kunyang; Wang, Qian; Chen, Wenhui; Song, Rong; Liu, Guanzheng

    2017-09-01

    Grip force control is a crucial function for human to guarantee the quality of life. To examine the effects of age on grip force control, 10 young adults and 11 late middle-aged adults participated in visually guided tracking tasks using different target force levels (25, 50, and 75% of the subject's maximal grip force). Multiple measures were used to evaluate the tracking performance during force rising phase and force maintenance phase. The measurements include the rise time, fuzzy entropy, mean force percentage, coefficient of variation, and target deviation ratio. The results show that the maximal grip force was significantly lower in the late middle-aged adults than in the young adults. The time of rising phase was systematically longer among late middle-aged adults. The fuzzy entropy is a useful indicator for quantitating the force variability of the grip force signal at higher force levels. These results suggest that the late middle-aged adults applied a compensatory strategy that allow allows for sufficient time to reach the required grip force and reduce the impact of the early and subtle degenerative changes in hand motor function.

  4. Influences of load characteristics on impaired control of grip forces in patients with cerebellar damage.

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    Brandauer, B; Timmann, D; Häusler, A; Hermsdörfer, J

    2010-02-01

    Various studies showed a clear impairment of cerebellar patients to modulate grip force in anticipation of the loads resulting from movements with a grasped object. This failure corroborated the theory of internal feedforward models in the cerebellum. Cerebellar damage also impairs the coordination of multiple-joint movements and this has been related to deficient prediction and compensation of movement-induced torques. To study the effects of disturbed torque control on feedforward grip-force control, two self-generated load conditions with different demands on torque control-one with movement-induced and the other with isometrically generated load changes-were directly compared in patients with cerebellar degeneration. Furthermore the cerebellum is thought to be more involved in grip-force adjustment to self-generated loads than to externally generated loads. Consequently, an additional condition with externally generated loads was introduced to further test this hypothesis. Analysis of 23 patients with degenerative cerebellar damage revealed clear impairments in predictive feedforward mechanisms in the control of both self-generated load types. Besides feedforward control, the cerebellar damage also affected more reactive responses when the externally generated load destabilized the grip, although this impairment may vary with the type of load as suggested by control experiments. The present findings provide further support that the cerebellum plays a major role in predictive control mechanisms. However, this impact of the cerebellum does not strongly depend on the nature of the load and the specific internal forward model. Contributions to reactive (grip force) control are not negligible, but seem to be dependent on the physical characteristics of an externally generated load.

  5. Fitts’ Law in the Control of Isometric Grip Force With Naturalistic Targets

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    Zachary C. Thumser

    2018-04-01

    Full Text Available Fitts’ law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts’ law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design. We examined whether Fitts’ law would hold when participants attempted to accurately produce their intended force output while grasping a manipulandum when presented with images of various everyday objects (we termed this the implicit task. Although our main interest was the implicit task, to benchmark it and establish validity, we examined performance against a more standard visual feedback condition via a digital force-feedback meter on a video monitor (explicit task. Next, we progressed from visual force feedback with force meter targets to the same targets without visual force feedback (operating largely on feedforward control with tactile feedback. This provided an opportunity to see if Fitts’ law would hold without vision, and allowed us to progress toward the more naturalistic implicit task (which does not include visual feedback. Finally, we changed the nature of the targets from requiring explicit force values presented as arrows on a force-feedback meter (explicit targets to the more naturalistic and intuitive target forces implied by images of objects (implicit targets. With visual force feedback the relation between task difficulty and the time to produce the target grip force was predicted by Fitts’ law (average r2 = 0.82. Without vision, average grip force scaled accurately although force variability was insensitive to the target presented. In contrast, images of everyday objects generated more reliable grip forces

  6. Fitts' Law in the Control of Isometric Grip Force With Naturalistic Targets.

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    Thumser, Zachary C; Slifkin, Andrew B; Beckler, Dylan T; Marasco, Paul D

    2018-01-01

    Fitts' law models the relationship between amplitude, precision, and speed of rapid movements. It is widely used to quantify performance in pointing tasks, study human-computer interaction, and generally to understand perceptual-motor information processes, including research to model performance in isometric force production tasks. Applying Fitts' law to an isometric grip force task would allow for quantifying grasp performance in rehabilitative medicine and may aid research on prosthetic control and design. We examined whether Fitts' law would hold when participants attempted to accurately produce their intended force output while grasping a manipulandum when presented with images of various everyday objects (we termed this the implicit task). Although our main interest was the implicit task, to benchmark it and establish validity, we examined performance against a more standard visual feedback condition via a digital force-feedback meter on a video monitor (explicit task). Next, we progressed from visual force feedback with force meter targets to the same targets without visual force feedback (operating largely on feedforward control with tactile feedback). This provided an opportunity to see if Fitts' law would hold without vision, and allowed us to progress toward the more naturalistic implicit task (which does not include visual feedback). Finally, we changed the nature of the targets from requiring explicit force values presented as arrows on a force-feedback meter (explicit targets) to the more naturalistic and intuitive target forces implied by images of objects (implicit targets). With visual force feedback the relation between task difficulty and the time to produce the target grip force was predicted by Fitts' law (average r 2 = 0.82). Without vision, average grip force scaled accurately although force variability was insensitive to the target presented. In contrast, images of everyday objects generated more reliable grip forces without the visualized

  7. Effects of Anodal Transcranial Direct Current Stimulation on Visually Guided Learning of Grip Force Control

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    Tamas Minarik

    2015-03-01

    Full Text Available Anodal transcranial Direct Current Stimulation (tDCS has been shown to be an effective non-invasive brain stimulation method for improving cognitive and motor functioning in patients with neurological deficits. tDCS over motor cortex (M1, for instance, facilitates motor learning in stroke patients. However, the literature on anodal tDCS effects on motor learning in healthy participants is inconclusive, and the effects of tDCS on visuo-motor integration are not well understood. In the present study we examined whether tDCS over the contralateral motor cortex enhances learning of grip-force output in a visually guided feedback task in young and neurologically healthy volunteers. Twenty minutes of 1 mA anodal tDCS were applied over the primary motor cortex (M1 contralateral to the dominant (right hand, during the first half of a 40 min power-grip task. This task required the control of a visual signal by modulating the strength of the power-grip for six seconds per trial. Each participant completed a two-session sham-controlled crossover protocol. The stimulation conditions were counterbalanced across participants and the sessions were one week apart. Performance measures comprised time-on-target and target-deviation, and were calculated for the periods of stimulation (or sham and during the afterphase respectively. Statistical analyses revealed significant performance improvements over the stimulation and the afterphase, but this learning effect was not modulated by tDCS condition. This suggests that the form of visuomotor learning taking place in the present task was not sensitive to neurostimulation. These null effects, together with similar reports for other types of motor tasks, lead to the proposition that tDCS facilitation of motor learning might be restricted to cases or situations where the motor system is challenged, such as motor deficits, advanced age, or very high task demand.

  8. Adjustment of gripping force by optical systems

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    Jalba, C. K.; Barz, C.

    2018-01-01

    With increasing automation, robotics also requires ever more intelligent solutions in the handling of various tasks. In this context, many grippers must also be re-designed. For this, they must always be adapted for different requirements. The equipment of the gripper systems with sensors should help to make the gripping process more intelligent. In order to achieve such objectives, optical systems can also be used. This work analyzes how the gripping force can be adjusted by means of an optical recognition. The result of this work is the creation of a connection between optical recognition, tolerances, gripping force and real-time control. In this way, algorithms can be created, with the aid of which robot grippers as well as other gripping systems become more intelligent.

  9. Superposition of automatic and voluntary aspects of grip force control in humans during object manipulation.

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    Frederic Danion

    Full Text Available When moving grasped objects, people automatically modulate grip force (GF with movement-dependent load force (LF in order to prevent object slip. However, GF can also be modulated voluntarily as when squeezing an object. Here we investigated possible interactions between automatic and voluntary GF control. Participants were asked to generate horizontal cyclic movements (between 0.6 and 2.0 Hz of a hand-held object that was restrained by an elastic band such that the load force (LF reached a peak once per movement cycle, and to simultaneously squeeze the object at each movement reversal (i.e., twice per cycle. Participants also performed two control tasks in which they either only moved (between 0.6 and 2.0 Hz or squeezed (between 1.2 and 4.0 Hz the object. The extent to which GF modulation in the simultaneous task could be predicted from the two control tasks was assessed using power spectral analyses. At all frequencies, the GF power spectra from the simultaneous task exhibited two prominent components that occurred at the cycle frequency (ƒ and at twice this frequency (2ƒ, whereas the spectra from the movement and squeeze control task exhibited only single peaks at ƒ and 2ƒ, respectively. At lower frequencies, the magnitudes of both frequency components in the simultaneous task were similar to the magnitudes of the corresponding components in the control tasks. However, as frequency increased, the magnitudes of both components in the simultaneous task were greater than the magnitudes of the corresponding control task components. Moreover, the phase relationship between the ƒ components of GF and LF began to drift from the value observed in the movement control task. Overall these results suggest that, at lower movement frequencies, voluntary and automatic GF control processes operate at different hierarchical levels. Several mechanisms are discussed to account for interaction effects observed at higher movement frequencies.

  10. White matter organization in cervical spinal cord relates differently to age and control of grip force in healthy subjects.

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    Lindberg, Påvel G; Feydy, Antoine; Maier, Marc A

    2010-03-17

    Diffusion tensor imaging (DTI) can be used to elucidate relations between CNS structure and function. We hypothesized that the degree of spinal white matter organization relates to the accuracy of control of grip force. Healthy subjects of different age were studied using DTI and visuomotor tracking of precision grip force. The latter is a prime component of manual dexterity. A regional analysis of spinal white matter [fractional anisotropy (FA)] across multiple cervical levels (C2-C3, C4-C5, and C6-C7) and in different regions of interest (left and right lateral or medial spinal cord) was performed. FA was highest at the C2-C3 level, higher on the right than the left side, and higher in the lateral than in the medial spinal cord (p level in the lateral spinal cord, in which the corticospinal tract innervates spinal circuitry controlling hand and digit muscles. FA of the medial spinal cord correlated consistently with age across all cervical levels, whereas FA of the lateral spinal cord did not. The results suggest (1) a functionally relevant specialization of lateral spinal cord white matter and (2) an increased sensitivity to age-related decline in medial spinal cord white matter in healthy subjects.

  11. Bilateral deficits in fine motor control and pinch grip force are not associated with electrodiagnostic findings in women with carpal tunnel syndrome.

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    de la Llave-Rincón, Ana Isabel; Fernández-de-Las-Peñas, César; Pérez-de-Heredia-Torres, Marta; Martínez-Perez, Almudena; Valenza, Marie Carmen; Pareja, Juan A

    2011-06-01

    : The aim of this study was to analyze the differences in deficits in fine motor control and pinch grip force between patients with minimal, moderate/mild, or severe carpal tunnel syndrome (CTS) and healthy age- and hand dominance-matched controls. : A case-control study was conducted. The subtests of the Purdue Pegboard Test (one-hand and bilateral pin placements and assemblies) and pinch grip force between the thumb and the remaining four fingers of the hand were bilaterally evaluated in 66 women with minimal (n = 16), moderate (n = 16), or severe (n = 34) CTS and in 20 age- and hand-matched healthy women. The differences among the groups were analyzed using different mixed models of analysis of variance. : A two-way mixed analysis of variance revealed significant differences between groups, not depending on the presence of unilateral or bilateral symptoms (side), for the one-hand pin placement subtest: patients showed bilateral lower scores compared with controls (P < 0.001), without differences among those with minimal, moderate, or severe CTS (P = 0.946). The patients also exhibited lower scores in bilateral pin placement (P < 0.001) and assembly (P < 0.001) subtests, without differences among them. The three-way analysis of variance revealed significant differences among groups (P < 0.001) and fingers (P < 0.001), not depending on the presence of unilateral/bilateral symptoms (P = 0.684), for pinch grip force: patients showed bilateral lower pinch grip force in all fingers compared with healthy controls, without differences among those with minimal, moderate, or severe CTS. : The current study revealed similar bilateral deficits in fine motor control and pinch grip force in patients with minimal, moderate, or severe CTS, supporting that fine motor control deficits are a common feature of CTS not associated with electrodiagnostic findings.

  12. Contribution of the Cerebellum in Cue-Dependent Force Changes During an Isometric Precision Grip Task.

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    Kutz, Dieter F; Schmid, Barbara C; Meindl, Tobias; Timmann, Dagmar; Kolb, Florian P

    2016-08-01

    The "raspberry task" represents a precision grip task that requires continuous adjustment of grip forces and pull forces. During this task, subjects use a specialised grip rod and have to increase the pull force linearly while the rod is locked. The positions of the fingers are unrestrained and freely selectable. From the finger positions and the geometry of the grip rod, a physical lever was derived which is a comprehensive measurement of the subject's grip behaviour. In this study, the involvement of the cerebellum in establishing cued force changes (CFC) was examined. The auditory stimulus was associated with a motor behaviour that has to be readjusted during an ongoing movement that already started. Moreover, cerebellar involvement on grip behaviour was examined. The results show that patients presenting with degenerating cerebellar disease (CBL) were able to elicit CFC and were additionally able to optimise grip behaviour by minimising the lever. Comparison of the results of CBL with a control group of healthy subjects showed, however, that the CFC incidence was significantly lower and the reduction of the lever was less in CBL. Hence, the cerebellum is involved not only in the classical conditioning of reflexes but also in the association of sensory stimuli with complex changes in motor behaviour. Furthermore, the cerebellum is involved in the optimisation of grip behaviour during ongoing movements. Recent studies lead to the assumption that the cerebello-reticulo-spinal pathway might be important for the reduced optimisation of grip behaviour in CBL.

  13. Muscle Fatigue in the Three Heads of the Triceps Brachii During a Controlled Forceful Hand Grip Task with Full Elbow Extension Using Surface Electromyography.

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    Ali, Asraf; Sundaraj, Kenneth; Badlishah Ahmad, R; Ahamed, Nizam Uddin; Islam, Anamul; Sundaraj, Sebastian

    2015-06-27

    The objective of the present study was to investigate the time to fatigue and compare the fatiguing condition among the three heads of the triceps brachii muscle using surface electromyography during an isometric contraction of a controlled forceful hand grip task with full elbow extension. Eighteen healthy subjects concurrently performed a single 90 s isometric contraction of a controlled forceful hand grip task and full elbow extension. Surface electromyographic signals from the lateral, long and medial heads of the triceps brachii muscle were recorded during the task for each subject. The changes in muscle activity among the three heads of triceps brachii were measured by the root mean square values for every 5 s period throughout the total contraction period. The root mean square values were then analysed to determine the fatiguing condition for the heads of triceps brachii muscle. Muscle fatigue in the long, lateral, and medial heads of the triceps brachii started at 40 s, 50 s, and 65 s during the prolonged contraction, respectively. The highest fatiguing rate was observed in the long head (slope = -2.863), followed by the medial head (slope = -2.412) and the lateral head (slope = -1.877) of the triceps brachii muscle. The results of the present study concurs with previous findings that the three heads of the triceps brachii muscle do not work as a single unit, and the fiber type/composition is different among the three heads.

  14. Adaptive grip force is modulated by subthalamic beta activity in Parkinson's disease patients

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    Lukas L. Imbach

    2015-01-01

    Conclusion: The time-locked suppression of beta oscillatory activity in the STN is in line with previous reports of beta ERD prior to voluntary movements. Our results show that the STN is involved in anticipatory grip force control in PD patients. The difference in the phasic beta ERD between the two tasks and the reduction of cortico-subthalamic synchronization suggests that qualitatively different neuronal network states are involved in different grip force control tasks.

  15. The brain adjusts grip forces differently according to gravity and inertia: a parabolic flight experiment

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    Olivier eWhite

    2015-02-01

    Full Text Available In everyday life, one of the most frequent activities involves accelerating and decelerating an object held in precision grip. In many contexts, humans scale and synchronize their grip force, normal to the finger/object contact, in anticipation of the expected tangential load force, resulting from the combination of the gravitational and the inertial forces. In many contexts, grip force and load force are linearly coupled. A few studies have examined how we adjust the parameters - gain and offset - of this linear relationship. However, the question remains open as to how the brain adjusts grip force regardless of whether load force is generated by different combinations of weight and inertia. Here, we designed conditions to generate equivalent magnitudes of load force by independently varying mass and movement frequency. In a control experiment, we directly manipulated gravity in parabolic flights, while other factors remained constant. We show with a simple computational approach that, to adjust grip force, the brain is sensitive to how load forces are produced at the fingertips. This provides clear evidence that the analysis of the origin of load force is performed centrally, and not only at the periphery.

  16. Inertial torque during reaching directly impacts grip-force adaptation to weightless objects.

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    Giard, T; Crevecoeur, F; McIntyre, J; Thonnard, J-L; Lefèvre, P

    2015-11-01

    A hallmark of movement control expressed by healthy humans is the ability to gradually improve motor performance through learning. In the context of object manipulation, previous work has shown that the presence of a torque load has a direct impact on grip-force control, characterized by a significantly slower grip-force adjustment across lifting movements. The origin of this slower adaptation rate remains unclear. On the one hand, information about tangential constraints during stationary holding may be difficult to extract in the presence of a torque. On the other hand, inertial torque experienced during movement may also potentially disrupt the grip-force adjustments, as the dynamical constraints clearly differ from the situation when no torque load is present. To address the influence of inertial torque loads, we instructed healthy adults to perform visually guided reaching movements in weightlessness while holding an unbalanced object relative to the grip axis. Weightlessness offered the possibility to remove gravitational constraints and isolate the effect of movement-related feedback on grip force adjustments. Grip-force adaptation rates were compared with a control group who manipulated a balanced object without any torque load and also in weightlessness. Our results clearly show that grip-force adaptation in the presence of a torque load is significantly slower, which suggests that the presence of torque loads experienced during movement may alter our internal estimates of how much force is required to hold an unbalanced object stable. This observation may explain why grasping objects around the expected location of the center of mass is such an important component of planning and control of manipulation tasks.

  17. Anticipatory grip force between 1 and 3g

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    White, Olivier; Van Loon, ing.. Jack J. W. A.; Thonnard, Jean-Louis; Hermsdorfer, Joachim; Lefevre, Philippe

    One remarkable capacity of utilizing common tools appropriately as soon as we grasp them relies on the ability to determine in advance the grip force (GF) required to handle them in relation to their mechanical properties and the surrounding environment. This anticipatory strategy avoids the uncompressible delays in the feedback system. The predictive control of GF is made possible because the nervous system can learn, store and then select the internal representations of the dynamics of innumerable objects, known as internal models. Beside this flexibility, the nervous system's ability to learn different task dynamics is often limited in classical robotic experiments The environment itself can be profoundly modified in altered gravity or centrifugation. The few studies that investigated motor adaptation in such contexts did not consider the interaction between gravitational phases and even less the transitions across environments. Here, we tested subject's abilities to adapt to levels of gravitational fields generated by a human centrifuge. In Experiment 1, seven subjects performed 4 lifting trials in each gravitational phase (1 to 2.5g and then 2.5 to 1g by steps of 0.5g) with a 0.12 kg instrumented object. In Experiment 2, six subjects performed vertical oscillations of the object during transitions between 1 and 3g (0.5g steps, ascending and descending phases, profile repeated twice). We continuously measured GF, load force (LF) and ambient gravity. We hypothesized that participants were able to predictively adjust GF to the new environment. In Experiment 1, participants adjusted their GF proportionally to gravity and decreased GF across trials within a given gravitational environment. Preload phases decreased over time from 300ms to 50ms irrespective of gravity. We quantified the abilities of participants to switch across environments by subtracting GF recorded in the last trial in the current gravity level from GF during the first trial in the new environment

  18. Phalanx force magnitude and trajectory deviation increased during power grip with an increased coefficient of friction at the hand-object interface.

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    Enders, Leah R; Seo, Na Jin

    2011-05-17

    This study examined the effect of friction between the hand and grip surface on a person's grip strategy and force generation capacity. Twelve young healthy adults performed power grip exertions on an instrumented vertical cylinder with the maximum and 50% of maximum efforts (far above the grip force required to hold the cylinder), while normal and shear forces at each phalanx of all five fingers in the direction orthogonal to the gravity were recorded. The cylinder surface was varied for high-friction rubber and low-friction paper coverings. An increase in surface friction by replacing the paper covering with the rubber covering resulted in 4% greater mean phalanx normal force (perpendicular to the cylinder surface) and 22% greater mean phalanx shear force in either the proximal or distal direction of the digits (pfriction with the rubber surface compared to the paper surface was associated with a 20% increase in the angular deviation of the phalanx force from the direction normal to the cylinder surface (p<0.05). This study demonstrates that people significantly changed the magnitude and direction of phalanx forces depending on the surface they gripped. Such change in the grip strategy appears to help increase grip force generation capacity. This finding suggests that a seemingly simple power grip exertion involves sensory feedback-based motor control, and that people's power grip capacity may be reduced in cases of numbness, glove use, or injuries resulting in reduced sensation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. Quantification of hand function by power grip and pinch strength force measurements in ulnar nerve lesion simulated by ulnar nerve block.

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    Wachter, Nikolaus Johannes; Mentzel, Martin; Krischak, Gert D; Gülke, Joachim

    2017-06-24

    In the assessment of hand and upper limb function, grip strength is of the major importance. The measurement by dynamometers has been established. In this study, the effect of a simulated ulnar nerve lesion on different grip force measurements was evaluated. In 25 healthy volunteers, grip force measurement was done by the JAMAR dynamometer (Fabrication Enterprises Inc, Irvington, NY) for power grip and by a pinch strength dynamometer for tip pinch strength, tripod grip, and key pinch strength. A within-subject research design was used in this prospective study. Each subject served as the control by preinjection measurements of grip and pinch strength. Subsequent measurements after ulnar nerve block were used to examine within-subject change. In power grip, there was a significant reduction of maximum grip force of 26.9% with ulnar nerve block compared with grip force without block (P force could be confirmed. However, the assessment of other dimensions of hand strength as tip pinch, tripod pinch and key pinch had more relevance in demonstrating hand strength changes resulting from an distal ulnar nerve lesion. The measurement of tip pinch, tripod grip and key pinch can improve the follow-up in hand rehabilitation. II. Copyright © 2017 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  20. Development of force sensing circuit to determine the optimal force required for effective dynamic tripod grip/writing

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    Suraj S., S.; Kulkarni, Palash; Bokadia, Pratik; Ramanathan, Prabhu; Nageswaran, Sharmila

    2018-04-01

    Handwriting is a combination of fine motor perceptions and cognitive skills to produce words on paper. For writing, the most commonly used and recommended grip is the dynamic tripod grip. A child's handwriting starts developing during the times of pre-schooling and improves over time. While writing, children apply excessive force on the writing instrument. This force is exerted by their fingers and as per the law of reaction, the writing instruments tend to exert an equal and opposite force, that could damage the delicate soft tissue structures in their fingers and initiate cramps and pains. This condition is also prevalent in adults who tend to write for long hours under pressure. An example would be adolescence student during the exams. Clinically this condition is termed as `Writer's Cramp', which is usually characterized by muscle fatigue and pain in the fingers. By understanding and fixing the threshold of the force that should be exerted by the fingers while gripping the instrument, the pain can be controlled or avoided. This research aims in designing an electronic module which can help in understanding the threshold of pressure which is optimum enough to establish a better contact between the fingers and the instrument and should be capable of controlling or avoiding the pain. The design of FSR based electronic system is explained with its circuitry and results of initial testing is presented in this paper.

  1. An Overview on Gripping Force Measurement at the Micro and Nano-Scales Using Two-Fingered Microrobotic Systems

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    Mokrane Boudaoud

    2014-03-01

    Full Text Available Two-fingered micromanipulation systems with an integrated force sensor are widely used in robotics to sense and control gripping forces at the micro and nano-scales. They became of primary importance for an efficient manipulation and characterization of highly deformable biomaterials and nanostructures. This paper presents a chronological overview of gripping force measurement using two-fingered micromanipulation systems. The work summarizes the major achievements in this field from the early 90s to the present, focusing in particular on the evolution of measurement technologies regarding the requirements of microrobotic applications. Measuring forces below the microNewton for the manipulation of highly deformable materials, embedding force sensors within microgrippers to increase their dexterity, and reducing the influence of noise to improve the measurement resolution are among the addressed challenges. The paper shows different examples of how these challenges have been addressed. Resolution, operating range and signal/noise ratio of gripping force sensors are reported and compared. A discussion about force measurement technologies and gripping force control is performed and future trends are highlighted.

  2. Grip Force and 3D Push-Pull Force Estimation Based on sEMG and GRNN

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    Changcheng Wu

    2017-06-01

    Full Text Available The estimation of the grip force and the 3D push-pull force (push and pull force in the three dimension space from the electromyogram (EMG signal is of great importance in the dexterous control of the EMG prosthetic hand. In this paper, an action force estimation method which is based on the eight channels of the surface EMG (sEMG and the Generalized Regression Neural Network (GRNN is proposed to meet the requirements of the force control of the intelligent EMG prosthetic hand. Firstly, the experimental platform, the acquisition of the sEMG, the feature extraction of the sEMG and the construction of GRNN are described. Then, the multi-channels of the sEMG when the hand is moving are captured by the EMG sensors attached on eight different positions of the arm skin surface. Meanwhile, a grip force sensor and a three dimension force sensor are adopted to measure the output force of the human's hand. The characteristic matrix of the sEMG and the force signals are used to construct the GRNN. The mean absolute value and the root mean square of the estimation errors, the correlation coefficients between the actual force and the estimated force are employed to assess the accuracy of the estimation. Analysis of variance (ANOVA is also employed to test the difference of the force estimation. The experiments are implemented to verify the effectiveness of the proposed estimation method and the results show that the output force of the human's hand can be correctly estimated by using sEMG and GRNN method.

  3. Real time relationship between individual finger force and grip exertion on distal phalanges in linear force following tasks.

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    Luo, Shi-Jian; Shu, Ge; Gong, Yan

    2018-05-01

    Individual finger force (FF) in a grip task is a vital concern in rehabilitation engineering and precise control of manipulators because disorders in any of the fingers will affect the stability or accuracy of the grip force (GF). To understand the functions of each finger in a dynamic grip exertion task, a GF following experiment with four individual fingers without thumb was designed. This study obtained four individual FFs from the distal phalanges with a cylindrical handle in dynamic GF following tasks. Ten healthy male subjects with similar hand sizes participated in the four-finger linear GF following tasks at different submaximal voluntary contraction (SMVC) levels. The total GF, individual FF, finger force contribution, and following error were subsequently calculated and analyzed. The statistics indicated the following: 1) the accuracy and stability of GF at low %MVC were significantly higher than those at high SMVC; 2) at low SMVC, the ability of the fingers to increase the GF was better than the ability to reduce it, but it was contrary at high SMVC; 3) when the target wave (TW) was changing, all four fingers strongly participated in the force exertion, but the participation of the little finger decreased significantly when TW remained stable; 4) the index finger and ring finger had a complementary relationship and played a vital role in the adjustment and control of GF. The middle finger and little finger had a minor influence on the force control and adjustment. In conclusion, each of the fingers had different functions in a GF following task. These findings can be used in the assessment of finger injury rehabilitation and for algorithms of precise control. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Grip Force Adjustments Reflect Prediction of Dynamic Consequences in Varying Gravitoinertial Fields

    Directory of Open Access Journals (Sweden)

    Olivier White

    2018-02-01

    Full Text Available Humans have a remarkable ability to adjust the way they manipulate tools through a genuine regulation of grip force according to the task. However, rapid changes in the dynamical context may challenge this skill, as shown in many experimental approaches. Most experiments adopt perturbation paradigms that affect only one sensory modality. We hypothesize that very fast adaptation can occur if coherent information from multiple sensory modalities is provided to the central nervous system. Here, we test whether participants can switch between different and never experienced dynamical environments induced by centrifugation of the body. Seven participants lifted an object four times in a row successively in 1, 1.5, 2, 2.5, 2, 1.5, and 1 g. We continuously measured grip force, load force and the gravitoinertial acceleration that was aligned with body axis (perceived gravity. Participants adopted stereotyped grasping movements immediately upon entry in a new environment and needed only one trial to adapt grip forces to a stable performance in each new gravity environment. This result was underlined by good correlations between grip and load forces in the first trial. Participants predictively applied larger grip forces when they expected increasing gravity steps. They also decreased grip force when they expected decreasing gravity steps, but not as much as they could, indicating imperfect anticipation in that condition. The participants' performance could rather be explained by a combination of successful scaling of grip force according to gravity changes and a separate safety factor. The data suggest that in highly unfamiliar dynamic environments, grip force regulation is characterized by a combination of a successful anticipation of the experienced environmental condition, a safety factor reflecting strategic response to uncertainties about the environment and rapid feedback mechanisms to optimize performance under constant conditions.

  5. Key Insights into Hand Biomechanics: Human Grip Stiffness Can Be Decoupled from Force by Cocontraction and Predicted from Electromyography

    Directory of Open Access Journals (Sweden)

    Hannes Höppner

    2017-05-01

    Full Text Available We investigate the relation between grip force and grip stiffness for the human hand with and without voluntary cocontraction. Apart from gaining biomechanical insight, this issue is particularly relevant for variable-stiffness robotic systems, which can independently control the two parameters, but for which no clear methods exist to design or efficiently exploit them. Subjects were asked in one task to produce different levels of force, and stiffness was measured. As expected, this task reveals a linear coupling between force and stiffness. In a second task, subjects were then asked to additionally decouple stiffness from force at these force levels by using cocontraction. We measured the electromyogram from relevant groups of muscles and analyzed the possibility to predict stiffness and force. Optical tracking was used for avoiding wrist movements. We found that subjects were able to decouple grip stiffness from force when using cocontraction on average by about 20% of the maximum measured stiffness over all force levels, while this ability increased with the applied force. This result contradicts the force–stiffness behavior of most variable-stiffness actuators. Moreover, we found the thumb to be on average twice as stiff as the index finger and discovered that intrinsic hand muscles predominate our prediction of stiffness, but not of force. EMG activity and grip force allowed to explain 72 ± 12% of the measured variance in stiffness by simple linear regression, while only 33 ± 18% variance in force. Conclusively the high signal-to-noise ratio and the high correlation to stiffness of these muscles allow for a robust and reliable regression of stiffness, which can be used to continuously teleoperate compliance of modern robotic hands.

  6. The brain adjusts grip forces differently according to gravity and inertia: a parabolic flight experiment

    Science.gov (United States)

    White, Olivier

    2015-01-01

    In everyday life, one of the most frequent activities involves accelerating and decelerating an object held in precision grip. In many contexts, humans scale and synchronize their grip force (GF), normal to the finger/object contact, in anticipation of the expected tangential load force (LF), resulting from the combination of the gravitational and the inertial forces. In many contexts, GF and LF are linearly coupled. A few studies have examined how we adjust the parameters–gain and offset–of this linear relationship. However, the question remains open as to how the brain adjusts GF regardless of whether LF is generated by different combinations of weight and inertia. Here, we designed conditions to generate equivalent magnitudes of LF by independently varying mass and movement frequency. In a control experiment, we directly manipulated gravity in parabolic flights, while other factors remained constant. We show with a simple computational approach that, to adjust GF, the brain is sensitive to how LFs are produced at the fingertips. This provides clear evidence that the analysis of the origin of LF is performed centrally, and not only at the periphery. PMID:25717293

  7. Probabilistic information on object weight shapes force dynamics in a grip-lift task.

    Science.gov (United States)

    Trampenau, Leif; Kuhtz-Buschbeck, Johann P; van Eimeren, Thilo

    2015-06-01

    Advance information, such as object weight, size and texture, modifies predictive scaling of grip forces in a grip-lift task. Here, we examined the influence of probabilistic advance information about object weight. Fifteen healthy volunteers repeatedly grasped and lifted an object equipped with a force transducer between their thumb and index finger. Three clearly distinguishable object weights were used. Prior to each lift, the probabilities for the three object weights were given by a visual cue. We examined the effect of probabilistic pre-cues on grip and lift force dynamics. We expected predictive scaling of grip force parameters to follow predicted values calculated according to probabilistic contingencies of the cues. We observed that probabilistic cues systematically influenced peak grip and load force rates, as an index of predictive motor scaling. However, the effects of probabilistic cues on force rates were nonlinear, and anticipatory adaptations of the motor output generally seemed to overestimate high probabilities and underestimate low probabilities. These findings support the suggestion that anticipatory adaptations and force scaling of the motor system can integrate probabilistic information. However, probabilistic information seems to influence motor programs in a nonlinear fashion.

  8. The effect of force feedback delay on stiffness perception and grip force modulation during tool-mediated interaction with elastic force fields.

    Science.gov (United States)

    Leib, Raz; Karniel, Amir; Nisky, Ilana

    2015-05-01

    During interaction with objects, we form an internal representation of their mechanical properties. This representation is used for perception and for guiding actions, such as in precision grip, where grip force is modulated with the predicted load forces. In this study, we explored the relationship between grip force adjustment and perception of stiffness during interaction with linear elastic force fields. In a forced-choice paradigm, participants probed pairs of virtual force fields while grasping a force sensor that was attached to a haptic device. For each pair, they were asked which field had higher level of stiffness. In half of the pairs, the force feedback of one of the fields was delayed. Participants underestimated the stiffness of the delayed field relatively to the nondelayed, but their grip force characteristics were similar in both conditions. We analyzed the magnitude of the grip force and the lag between the grip force and the load force in the exploratory probing movements within each trial. Right before answering which force field had higher level of stiffness, both magnitude and lag were similar between delayed and nondelayed force fields. These results suggest that an accurate internal representation of environment stiffness and time delay was used for adjusting the grip force. However, this representation did not help in eliminating the bias in stiffness perception. We argue that during performance of a perceptual task that is based on proprioceptive feedback, separate neural mechanisms are responsible for perception and action-related computations in the brain. Copyright © 2015 the American Physiological Society.

  9. An exploration of grip force regulation with a low-impedance myoelectric prosthesis featuring referred haptic feedback.

    Science.gov (United States)

    Brown, Jeremy D; Paek, Andrew; Syed, Mashaal; O'Malley, Marcia K; Shewokis, Patricia A; Contreras-Vidal, Jose L; Davis, Alicia J; Gillespie, R Brent

    2015-11-25

    Haptic display technologies are well suited to relay proprioceptive, force, and contact cues from a prosthetic terminal device back to the residual limb and thereby reduce reliance on visual feedback. The ease with which an amputee interprets these haptic cues, however, likely depends on whether their dynamic signal behavior corresponds to expected behaviors-behaviors consonant with a natural limb coupled to the environment. A highly geared motor in a terminal device along with the associated high back-drive impedance influences dynamic interactions with the environment, creating effects not encountered with a natural limb. Here we explore grasp and lift performance with a backdrivable (low backdrive impedance) terminal device placed under proportional myoelectric position control that features referred haptic feedback. We fabricated a back-drivable terminal device that could be used by amputees and non-amputees alike and drove aperture (or grip force, when a stiff object was in its grasp) in proportion to a myoelectric signal drawn from a single muscle site in the forearm. In randomly ordered trials, we assessed the performance of N=10 participants (7 non-amputee, 3 amputee) attempting to grasp and lift an object using the terminal device under three feedback conditions (no feedback, vibrotactile feedback, and joint torque feedback), and two object weights that were indiscernible by vision. Both non-amputee and amputee participants scaled their grip force according to the object weight. Our results showed only minor differences in grip force, grip/load force coordination, and slip as a function of sensory feedback condition, though the grip force at the point of lift-off for the heavier object was significantly greater for amputee participants in the presence of joint torque feedback. An examination of grip/load force phase plots revealed that our amputee participants used larger safety margins and demonstrated less coordination than our non-amputee participants

  10. Investigation of index finger triggering force using a cadaver experiment: Effects of trigger grip span, contact location, and internal tendon force.

    Science.gov (United States)

    Chang, Joonho; Freivalds, Andris; Sharkey, Neil A; Kong, Yong-Ku; Mike Kim, H; Sung, Kiseok; Kim, Dae-Min; Jung, Kihyo

    2017-11-01

    A cadaver study was conducted to investigate the effects of triggering conditions (trigger grip span, contact location, and internal tendon force) on index finger triggering force and the force efficiency of involved tendons. Eight right human cadaveric hands were employed, and a motion simulator was built to secure and control the specimens. Index finger triggering forces were investigated as a function of different internal tendon forces (flexor digitorum profundus + flexor digitorum superficialis = 40, 70, and 100 N), trigger grip spans (40, 50, and 60 mm), and contact locations between the index finger and a trigger. Triggering forces significantly increased when internal tendon forces increased from 40 to 100 N. Also, trigger grip spans and contact locations had significant effects on triggering forces; maximum triggering forces were found at a 50 mm span and the most proximal contact location. The results revealed that only 10-30% of internal tendon forces were converted to their external triggering forces. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. The properties and interrelationships of various force-time parameters during maximal repeated rhythmic grip.

    Science.gov (United States)

    Nakada, Masakatsu; Demura, Shinichi; Yamaji, Shunsuke

    2007-01-01

    The purpose of this study was to examine the properties and interrelationships of various force-time parameters including the inflection point for the rate of decline in force during a maximal repeated rhythmic grip. Fifteen healthy males (age M=21.5, SD=2.1 yr, height M=172.4, SD=5.7 cm, body mass M=68.2, SD=9.2 kg) participated in this study. Subjects performed a maximal repeated rhythmic grip with maximal effort with a target frequency of 30 grip.min(-1) for 6 min. The force value decreased linearly and markedly until about 70% of maximal strength for about 55 s after the onset of a maximal repeated rhythmic grip, and then decreased moderately. Because all parameters showed fair or good correlations between 3 min and 6 min, they are considered to be able to sufficiently evaluate muscle endurance for 3 min instead of 6 min. However, there were significant differences between 3 min and 6 min in the integrated area, the final force, the rate of the decrement constant (k) fitting the force decreasing data to y=ae(-kx)+b and the force of maximal difference between the force and a straight line from peak force to the final force. Their parameters may vary generally by the length of a steady state, namely, a measurement time. The final force value before finishing and the rate of the decrement constant (k) reflect the latter phase during a maximal repeated rhythmic grip. Although many parameters show relatively high mutual relationships, the rate constant (k) shows relatively low correlations with other parameters. We inferred that decreasing the time until 80% of maximal strength and the amount of the decrement force for the first 1 min reflect a linear decrease in the initial phase.

  12. The bilateral movement condition facilitates maximal but not submaximal paretic-limb grip force in people with post-stroke hemiparesis

    Science.gov (United States)

    DeJong, Stacey L.; Lang, Catherine E.

    2012-01-01

    Objectives Although healthy individuals have less force production capacity during bilateral muscle contractions compared to unilateral efforts, emerging evidence suggests that certain aspects of paretic upper limb task performance after stroke may be enhanced by moving bilaterally instead of unilaterally. We investigated whether the bilateral movement condition affects grip force differently on the paretic side of people with post-stroke hemiparesis, compared to their non-paretic side and both sides of healthy young adults. Methods Within a single session, we compared: 1) maximal grip force during unilateral vs. bilateral contractions on each side, and 2) force contributed by each side during a 30% submaximal bilateral contraction. Results Healthy controls produced less grip force in the bilateral condition, regardless of side (- 2.4% difference), and similar findings were observed on the non-paretic side of people with hemiparesis (- 4.5% difference). On the paretic side, however, maximal grip force was increased by the bilateral condition in most participants (+11.3% difference, on average). During submaximal bilateral contractions in each group, the two sides each contributed the same percentage of unilateral maximal force. Conclusions The bilateral condition facilitates paretic limb grip force at maximal, but not submaximal levels. Significance In some people with post-stroke hemiparesis, the paretic limb may benefit from bilateral training with high force requirements. PMID:22248812

  13. Applying support vector regression analysis on grip force level-related corticomuscular coherence

    DEFF Research Database (Denmark)

    Rong, Yao; Han, Xixuan; Hao, Dongmei

    2014-01-01

    Voluntary motor performance is the result of cortical commands driving muscle actions. Corticomuscular coherence can be used to examine the functional coupling or communication between human brain and muscles. To investigate the effects of grip force level on corticomuscular coherence in an acces...

  14. Altered visual strategies and attention are related to increased force fluctuations during a pinch grip task in older adults.

    Science.gov (United States)

    Keenan, Kevin G; Huddleston, Wendy E; Ernest, Bradley E

    2017-11-01

    The purpose of the study was to determine the visual strategies used by older adults during a pinch grip task and to assess the relations between visual strategy, deficits in attention, and increased force fluctuations in older adults. Eye movements of 23 older adults (>65 yr) were monitored during a low-force pinch grip task while subjects viewed three common visual feedback displays. Performance on the Grooved Pegboard test and an attention task (which required no concurrent hand movements) was also measured. Visual strategies varied across subjects and depended on the type of visual feedback provided to the subjects. First, while viewing a high-gain compensatory feedback display (horizontal bar moving up and down with force), 9 of 23 older subjects adopted a strategy of performing saccades during the task, which resulted in 2.5 times greater force fluctuations in those that exhibited saccades compared with those who maintained fixation near the target line. Second, during pursuit feedback displays (force trace moving left to right across screen and up and down with force), all subjects exhibited multiple saccades, and increased force fluctuations were associated ( r s = 0.6; P = 0.002) with fewer saccades during the pursuit task. Also, decreased low-frequency (attention z scores. Comparison of these results with our previously published results in young subjects indicates that saccadic eye movements and attention are related to force control in older adults. NEW & NOTEWORTHY The significant contributions of the study are the addition of eye movement data and an attention task to explain differences in hand motor control across different visual displays in older adults. Older participants used different visual strategies across varying feedback displays, and saccadic eye movements were related with motor performance. In addition, those older individuals with deficits in attention had impaired motor performance on two different hand motor control tasks, including

  15. Performance of repetitive tasks induces decreased grip strength and increased fibrogenic proteins in skeletal muscle: role of force and inflammation.

    Directory of Open Access Journals (Sweden)

    Samir M Abdelmagid

    Full Text Available This study elucidates exposure-response relationships between performance of repetitive tasks, grip strength declines, and fibrogenic-related protein changes in muscles, and their link to inflammation. Specifically, we examined forearm flexor digitorum muscles for changes in connective tissue growth factor (CTGF; a matrix protein associated with fibrosis, collagen type I (Col1; a matrix component, and transforming growth factor beta 1 (TGFB1; an upstream modulator of CTGF and collagen, in rats performing one of two repetitive tasks, with or without anti-inflammatory drugs.To examine the roles of force versus repetition, rats performed either a high repetition negligible force food retrieval task (HRNF, or a high repetition high force handle-pulling task (HRHF, for up to 9 weeks, with results compared to trained only (TR-NF or TR-HF and normal control rats. Grip strength declined with both tasks, with the greatest declines in 9-week HRHF rats. Quantitative PCR (qPCR analyses of HRNF muscles showed increased expression of Col1 in weeks 3-9, and CTGF in weeks 6 and 9. Immunohistochemistry confirmed PCR results, and also showed greater increases of CTGF and collagen matrix in 9-week HRHF rats than 9-week HRNF rats. ELISA, and immunohistochemistry revealed greater increases of TGFB1 in TR-HF and 6-week HRHF, compared to 6-week HRNF rats. To examine the role of inflammation, results from 6-week HRHF rats were compared to rats receiving ibuprofen or anti-TNF-α treatment in HRHF weeks 4-6. Both treatments attenuated HRHF-induced increases in CTGF and fibrosis by 6 weeks of task performance. Ibuprofen attenuated TGFB1 increases and grip strength declines, matching our prior results with anti-TNFα.Performance of highly repetitive tasks was associated with force-dependent declines in grip strength and increased fibrogenic-related proteins in flexor digitorum muscles. These changes were attenuated, at least short-term, by anti-inflammatory treatments.

  16. Weight-specific anticipatory coding of grip force in human dorsal premotor cortex

    DEFF Research Database (Denmark)

    van Nuenen, Bart F L; Kuhtz-Buschbeck, Johann; Schulz, Christian

    2012-01-01

    , using either continuous theta burst stimulation (cTBS) at 80% (inhibitory cTBS) or 30% (sham cTBS) of active motor threshold. The conditioning effects of cTBS on preparatory brain activity were assessed with functional MRI, while participants lifted a light or heavy weight in response to a go-cue (S2......). An additional pre-cue (S1) correctly predicted the weight in 75% of the trials. Participants were asked to use this prior information to prepare for the lift. In the sham condition, grip force showed a consistent undershoot, if the S1 incorrectly prompted the preparation of a light lift. Likewise, an S1...... during object lifting....

  17. The role of left supplementary motor area in grip force scaling.

    Directory of Open Access Journals (Sweden)

    Olivier White

    Full Text Available Skilled tool use and object manipulation critically relies on the ability to scale anticipatorily the grip force (GF in relation to object dynamics. This predictive behaviour entails that the nervous system is able to store, and then select, the appropriate internal representation of common object dynamics, allowing GF to be applied in parallel with the arm motor commands. Although psychophysical studies have provided strong evidence supporting the existence of internal representations of object dynamics, known as "internal models", their neural correlates are still debated. Because functional neuroimaging studies have repeatedly designated the supplementary motor area (SMA as a possible candidate involved in internal model implementation, we used repetitive transcranial magnetic stimulation (rTMS to interfere with the normal functioning of left or right SMA in healthy participants performing a grip-lift task with either hand. TMS applied over the left, but not right, SMA yielded an increase in both GF and GF rate, irrespective of the hand used to perform the task, and only when TMS was delivered 130-180 ms before the fingers contacted the object. We also found that both left and right SMA rTMS led to a decrease in preload phase durations for contralateral hand movements. The present study suggests that left SMA is a crucial node in the network processing the internal representation of object dynamics although further experiments are required to rule out that TMS does not affect the GF gain. The present finding also further substantiates the left hemisphere dominance in scaling GF.

  18. Development of Hand Grip Assistive Device Control System for Old People through Electromyography (EMG) Signal Acquisitions

    OpenAIRE

    Khamis Herman; Mohamaddan Shahrol; Komeda Takashi; Alias Aidil Azli; Tanjong Shirley Jonathan; Julai Norhuzaimin; Hashim Nurul ‘Izzati

    2017-01-01

    The hand grip assistive device is a glove to assist old people who suffer from hand weakness in their daily life activities. The device earlier control system only use simple on and off switch. This required old people to use both hand to activate the device. The new control system of the hand grip assistive device was developed to allow single hand operation for old people. New control system take advantages of electromyography (EMG) and flex sensor which was implemented to the device. It wa...

  19. Serotonin and Histamine Therapy Increases Tetanic Forces of Myoblasts, Reduces Muscle Injury, and Improves Grip Strength Performance of Dmdmdx Mice

    Directory of Open Access Journals (Sweden)

    Volkan Gurel

    2015-11-01

    Full Text Available Duchenne muscular dystrophy (DMD is a recessive X-linked fatal disorder caused by a mutation in the dystrophin gene. Although several therapeutic approaches have been studied, none has led to substantial long-term effects in patients. The aim of this study was to test a serotonin and histamine (S&H combination on human skeletal myoblasts and Dmdmdx mice for its effects on muscle strength and injury. Normal human bioartificial muscles (BAMs were treated, and muscle tetanic forces and muscle injury tests were performed using the MyoForce Analysis System. Dmdmdx mice, the murine model of DMD, were administered serotonin, histamine, or S&H combination twice daily for 6 weeks, and functional performance tests were conducted once a week. The S&H combination treatment caused significant increases in tetanic forces at all time points and concentrations tested as compared to the saline controls. Dose response of the BAMs to the treatment demonstrated a significant increase in force generation at all concentrations compared to the controls after 3 to 4 days of drug treatment. The highest 3 concentrations had a significant effect on lowering contractile-induced injury as measured by a reduction in the release of adenylate kinase. Histamine-only and S&H treatments improved grip strength of Dmdmdx mice, whereas serotonin-only treatment resulted in no significant improvement in muscle strength. The results of this study indicate that S&H therapy might be a promising new strategy for muscular dystrophies and that the mechanism should be further investigated.

  20. Study on the collision-mechanical properties of tomatoes gripped by ...

    African Journals Online (AJOL)

    The data of collision-mechanical property of tomatoes gripped by robot fingers are important for the gripping control of tomato harvesting robot. In the study, tests of controlling the fingers to grip tomatoes were conducted to ascertain the effects of input current, motor speed and impact positions on the impact force of fingers ...

  1. Development of Hand Grip Assistive Device Control System for Old People through Electromyography (EMG Signal Acquisitions

    Directory of Open Access Journals (Sweden)

    Khamis Herman

    2017-01-01

    Full Text Available The hand grip assistive device is a glove to assist old people who suffer from hand weakness in their daily life activities. The device earlier control system only use simple on and off switch. This required old people to use both hand to activate the device. The new control system of the hand grip assistive device was developed to allow single hand operation for old people. New control system take advantages of electromyography (EMG and flex sensor which was implemented to the device. It was programmed into active and semi-active mode operation. EMG sensors were placed on the forearm to capture EMG signal of Flexor Digitorum Profundus muscle to activate the device. Flex sensor was used to indicate the finger position and placed on top of the finger. The signal from both sensors then used to control the device. The new control system allowed single hand operation and designed to prevent user from over depended on the device by activating it through moving their fingers.

  2. Grip force and heart rate responses to manual carrying tasks: effects of material, weight, and base area of the container.

    Science.gov (United States)

    Lee, Tzu-Hsien; Tseng, Chia-Yun

    2014-01-01

    This study recruited 16 industrial workers to examine the effects of material, weight, and base area of container on reduction of grip force (ΔGF) and heart rate for a 100-m manual carrying task. This study examined 2 carrying materials (iron and water), 4 carrying weights (4.4, 8.9, 13.3, 17.8 kg), and 2 base areas of container (24 × 24 cm, 35 × 24 cm). This study showed that carrying water significantly increased ΔGF and heart rate as compared with carrying iron. Also, ΔGF and heart rate significantly increased with carrying weight and base area of container. The effects of base area of container on ΔGF and heart rate were greater in carrying water condition than in carrying iron condition. The maximum dynamic effect of water on ΔGF and heart rate occurred when water occupied ~60%-80% of full volume of the container.

  3. Inferior frontal gyrus links visual and motor cortices during a visuomotor precision grip force task.

    Science.gov (United States)

    Papadelis, Christos; Arfeller, Carola; Erla, Silvia; Nollo, Giandomenico; Cattaneo, Luigi; Braun, Christoph

    2016-11-01

    Coordination between vision and action relies on a fronto-parietal network that receives visual and proprioceptive sensory input in order to compute motor control signals. Here, we investigated with magnetoencephalography (MEG) which cortical areas are functionally coupled on the basis of synchronization during visuomotor integration. MEG signals were recorded from twelve healthy adults while performing a unimanual visuomotor (VM) task and control conditions. The VM task required the integration of pinch motor commands with visual sensory feedback. By using a beamformer, we localized the neural activity in the frequency range of 1-30Hz during the VM compared to rest. Virtual sensors were estimated at the active locations. A multivariate autoregressive model was used to estimate the power and coherence of estimated activity at the virtual sensors. Event-related desynchronisation (ERD) during VM was observed in early visual areas, the rostral part of the left inferior frontal gyrus (IFG), the right IFG, the superior parietal lobules, and the left hand motor cortex (M1). Functional coupling in the alpha frequency band bridged the regional activities observed in motor and visual cortices (the start and the end points in the visuomotor loop) through the left or right IFG. Coherence between the left IFG and left M1 correlated inversely with the task performance. Our results indicate that an occipital-prefrontal-motor functional network facilitates the modulation of instructed motor responses to visual cues. This network may supplement the mechanism for guiding actions that is fully incorporated into the dorsal visual stream. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Effect of Insoles with a Toe-Grip Bar on Toe Function and Standing Balance in Healthy Young Women: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Hideki Nakano

    2017-01-01

    Full Text Available Objective. The aim of this randomized controlled study was to investigate the effects of insoles with a toe-grip bar on toe function and standing balance in healthy young women. Methods. Thirty female subjects were randomly assigned to an intervention group or a control group. The intervention group wore shoes with insoles with a toe-grip bar. The control group wore shoes with general insoles. Both groups wore the shoes for 4 weeks, 5 times per week, 9 hours per day. Toe-grip strength, toe flexibility, static balance (total trajectory length and envelope area of the center of pressure, and dynamic balance (functional reach test were measured before and after the intervention. Results. Significant interactions were observed for toe-grip strength and toe flexibility (F=12.53, p<0.01; F=5.84, p<0.05, resp., with significant improvement in the intervention group compared with that in the control group. Post hoc comparisons revealed that both groups showed significant improvement in toe-grip strength (p<0.01 and p<0.05, resp., with higher benefits observed for the intervention group (p<0.01. Conversely, no significant interaction was observed in the total trajectory length, envelope area, and functional reach test. Conclusions. This study suggests that insoles with a toe-grip bar contribute to improvements in toe-grip strength and toe flexibility in healthy young women.

  5. Effects of glovebox gloves on grip and key pinch strength and contact forces for simulated manual operations with three commonly used hand tools.

    Science.gov (United States)

    Sung, Peng-Cheng

    2014-01-01

    This study examined the effects of glovebox gloves for 11 females on maximum grip and key pinch strength and on contact forces generated from simulated tasks of a roller, a pair of tweezers and a crescent wrench. The independent variables were gloves fabricated of butyl, CSM/hypalon and neoprene materials; two glove thicknesses; and layers of gloves worn including single, double and triple gloving. CSM/hypalon and butyl gloves produced greater grip strength than the neoprene gloves. CSM/hypalon gloves also lowered contact forces for roller and wrench tasks. Single gloving and thin gloves improved hand strength performances. However, triple layers lowered contact forces for all tasks. Based on the evaluating results, selection and design recommendations of gloves for three hand tools were provided to minimise the effects on hand strength and optimise protection of the palmar hand in glovebox environments. To improve safety and health in the glovebox environments where gloves usage is a necessity, this study provides recommendations for selection and design of glovebox gloves for three hand tools including a roller, a pair of tweezers and a crescent wrench based on the results discovered in the experiments.

  6. Grip strength measurements at two different wrist extension positions in chronic lateral epicondylitis-comparison of involved vs. uninvolved side in athletes and non athletes: a case-control study

    Directory of Open Access Journals (Sweden)

    Bhargava Arti S

    2010-09-01

    Full Text Available Abstract Background Lateral epicondylitis is a common sports injury of the elbow caused due to altered muscle activation during repetitive wrist extension in many athletic and non-athletic endeavours. The amount of muscle activity and timing of contraction eventually is directly dependent upon joint position during the activity. The purpose of our study was to compare the grip strength in athletes with lateral epicondylalgia in two different wrist extension positions and compare them between involved and uninvolved sides of athletes and non-athletes. Methods An assessor-blinded case-control study of eight athletes and twenty-two non-athletes was done. The grip strength was measured using JAMAR® hand dynamometer in kilograms-force at 15 degrees (slightly extended and 35 degrees (moderately extended wrist extension positions (maintained by wrist splints on both involved and uninvolved sides of athletes and non-athletes with unilateral lateral epicondylitis of atleast 3 months duration. Their pain was to be elicited with local tenderness and two of three tests being positive- Cozen's, Mill's manoeuvre, resisted middle finger extension tests. For comparisons of grip strength, Wilcoxon signed rank test was used for within-group comparison (between 15 and 35 degrees wrist extension positions and Mann-Whitney U test was used for between-group (athletes vs. non-athletes comparisons at 95% confidence interval and were done using SPSS 11.5 for Windows. Results Statistically significant greater grip strength was found in 15 degrees (27.75 ± 4.2 kgms in athletes; 16.45 ± 4.2 kgms in non-athletes wrist extension than at 35 degrees (25.25 ± 3.53 kgm in athletes and 14.18 ± 3.53 kgm in non-athletes. The athletes had greater grip strength than non-athletes in each of test positions (11.3 kgm at 15 degrees and 11.07 kgm at 35 degrees measured. There was also a significant difference between involved and uninvolved sides' grip strength at both wrist

  7. Determination the validity of the new developed Sport Experts® hand grip dynamometer, measuring continuity of force, and comparison with current Takei and Baseline® dynamometers.

    Science.gov (United States)

    Güçlüöver, A; Kutlu, M; Ciğerci, A E; Esen, H T; Demirkan, E; Erdoğdu, M

    2015-11-01

    In this study the Sport Experts ™ brand of hand grip dynamometer, measuring the continuity of force with the new developed load cell technology, was compared with Takei and Baseline® dynamometers, the current in use. It was tried to determine the correlation between them. In a study with provides use of clinical, orthopedic and rehabilitative purposes in the athletes and patient populations, this developed dynamometer can provide useful data by observing the continuity of force. The sample of the study included 60 badminton players in 2010-2011; consisting of Turkish Junior National male players (N.=16, age: 16.8±1.5), Junior National female players (N.=14, age: 16.9±1.6), amateur level male players (N.=15, age: 16.3±0.8) and amateur level female players (N.=15, age: 16.1±0.6). ANOVA was used in the statistical methods in order to compare the hand grip strength made by different brands; Pearson's correlation coefficient was used to determine the relationship level between dynamometers. Furthermore, test-retest reliability analysis was completed the new developed expert dynamometer. There was no statistically significant difference in the comparison of the dynamometers (P>0.05). Besides, a highly significant relationship (r=0.95 to 0.96) was found among all three dynamometers. However, the reliability coefficient was found (Chronbachs α: 0.989, ICC:0.97, r=0.97), (Pexpert dynamometer. Comparison between the dynamometers and the statistical results obtained from the correlation relationships shows interchangeability of dynamometers. As a result, our observation of force continuity (progression) of the athlete and patient populations is thought to be important.

  8. Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis.

    Science.gov (United States)

    Schaefer, Sydney Y; DeJong, Stacey L; Cherry, Kendra M; Lang, Catherine E

    2012-04-01

    This study investigated whether grip type and/or task goal influenced reaching and grasping performance in poststroke hemiparesis. Sixteen adults with poststroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared with the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment.

  9. Effects of transcranial direct current stimulation on the control of finger force during dexterous manipulation in healthy older adults.

    Directory of Open Access Journals (Sweden)

    Pranav J Parikh

    Full Text Available The contribution of poor finger force control to age-related decline in manual dexterity is above and beyond ubiquitous behavioral slowing. Altered control of the finger forces can impart unwanted torque on the object affecting its orientation, thus impairing manual performance. Anodal transcranial direct current stimulation (tDCS over primary motor cortex (M1 has been shown to improve the performance speed on manual tasks in older adults. However, the effects of anodal tDCS over M1 on the finger force control during object manipulation in older adults remain to be fully explored. Here we determined the effects of anodal tDCS over M1 on the control of grip force in older adults while they manipulated an object with an uncertain mechanical property. Eight healthy older adults were instructed to grip and lift an object whose contact surfaces were unexpectedly made more or less slippery across trials using acetate and sandpaper surfaces, respectively. Subjects performed this task before and after receiving anodal or sham tDCS over M1 on two separate sessions using a cross-over design. We found that older adults used significantly lower grip force following anodal tDCS compared to sham tDCS. Friction measured at the finger-object interface remained invariant after anodal and sham tDCS. These findings suggest that anodal tDCS over M1 improved the control of grip force during object manipulation in healthy older adults. Although the cortical networks for representing objects and manipulative actions are complex, the reduction in grip force following anodal tDCS over M1 might be due to a cortical excitation yielding improved processing of object-specific sensory information and its integration with the motor commands for production of manipulative forces. Our findings indicate that tDCS has a potential to improve the control of finger force during dexterous manipulation in older adults.

  10. Force Myography to Control Robotic Upper Extremity Prostheses: A Feasibility Study

    Directory of Open Access Journals (Sweden)

    Erina eCho

    2016-03-01

    Full Text Available Advancement in assistive technology has led to the commercial availability of multi-dexterous robotic prostheses for the upper extremity. The relatively low performance of the currently used techniques to detect the intention of the user to control such advanced robotic prostheses, however, limits their use. This article explores the use of force myography (FMG as a potential alternative to the well-established surface electro-myography (sEMG. Specifically, the use of FMG to control different grips of a commercially available robotic hand, Bebionic3, are investigated. Four male transradially amputated subjects participated in the study and a protocol was developed to assess the prediction accuracy of eleven grips. Different combinations of grips were examined ranging from six up to eleven grips. The results indicate that it is possible to classify six primary grips important in activities of daily living using FMG with an accuracy of above 70% in the residual limb. Additional strategies to increase classification accuracy, such as using the available modes on the Bebionic3, allowed results to improve up to 88.83% and 89.00% for opposed thumb and non-opposed thumb modes respectively.

  11. Observing how others lift light or heavy objects: time-dependent encoding of grip force in the primary motor cortex.

    Science.gov (United States)

    Alaerts, Kaat; de Beukelaar, Toon T; Swinnen, Stephan P; Wenderoth, Nicole

    2012-07-01

    During movement observation, corticomotor excitability of the observer's primary motor cortex (M1) is modulated according to the force requirements of the observed action. Here, we explored the time course of observation-induced force encoding. Force-related changes in M1-excitability were assessed by delivering transcranial magnetic stimulations at distinct temporal phases of an observed reach-grasp-lift action. Temporal changes in force-related electromyographic activity were also assessed during active movement execution. In observation conditions in which a heavy object was lifted, M1-excitability was higher compared to conditions in which a light object was lifted. Both during observation and execution, differential force encoding tended to gradually increase from the grasping phase until the late lift phase. Surprisingly, however, during observation, force encoding was already present at the early reach phase: a time point at which no visual cues on the object's weight were available to the observer. As the observer was aware that the same weight condition was presented repeatedly, this finding may indicate that prior predictions concerning the upcoming weight condition are reflected by M1 excitability. Overall, findings may provide indications that the observer's motor system represents motor predictions as well as muscular requirements to infer the observed movement goal.

  12. Ulnar digits contribution to grip strength in patients with thumb carpometacarpal osteoarthritis is less than in normal controls.

    Science.gov (United States)

    Villafañe, Jorge H; Valdes, Kristin; Angulo-Diaz-Parreño, Santiago; Pillastrini, Paolo; Negrini, Stefano

    2015-06-01

    Grip testing is commonly used as an objective measure of strength in the hand and upper extremity and is frequently used clinically as a proxy measure of function. Increasing knowledge of hand biomechanics, muscle strength, and prehension patterns can provide us with a better understanding of the functional capabilities of the hand. The objectives of this study were to determine the contribution of ulnar digits to overall grip strength in individuals with thumb carpometacarpal (CMC) osteoarthritis (OA). Thirty-seven subjects participated in the study. This group consisted of 19 patients with CMC OA (aged 60-88 years) and 18 healthy subjects (60-88 years). Three hand configurations were used by the subjects during grip testing: use of the entire hand (index, middle, ring, and little fingers) (IMRL); use of the index, middle, and ring fingers (IMR); and use of only the index and middle fingers (IM). Grip strength findings for the two groups found that compared to their healthy counterparts, CMC OA patients had, on average, a strength deficiency of 45.6, 35.5, and 28.8 % in IMRL, IMR, and IM, respectively. The small finger contribution to grip is 14.3 % and the ring and small finger contribute 34 % in subjects with CMC OA. Grip strength decreases as the number of digits contributing decreased in both groups. The ulnar digits contribution to grip strength is greater than one third of total grip strength in subjects with CMC OA. Individuals with CMC OA demonstrate significantly decreased grip strength when compared to their healthy counterparts.

  13. Variability of grip kinetics during adult signature writing.

    Directory of Open Access Journals (Sweden)

    Bassma Ghali

    Full Text Available Grip kinetics and their variation are emerging as important considerations in the clinical assessment of handwriting pathologies, fine motor rehabilitation, biometrics, forensics and ergonomic pen design. This study evaluated the intra- and inter-participant variability of grip shape kinetics in adults during signature writing. Twenty (20 adult participants wrote on a digitizing tablet using an instrumented pen that measured the forces exerted on its barrel. Signature samples were collected over 10 days, 3 times a day, to capture temporal variations in grip shape kinetics. A kinetic topography (i.e., grip shape image was derived per signature by time-averaging the measured force at each of 32 locations around the pen barrel. The normalized cross correlations (NCC of grip shape images were calculated within- and between-participants. Several classification algorithms were implemented to gauge the error rate of participant discrimination based on grip shape kinetics. Four different grip shapes emerged and several participants made grip adjustments (change in grip shape or grip height or rotated the pen during writing. Nonetheless, intra-participant variation in grip kinetics was generally much smaller than inter-participant force variations. Using the entire grip shape images as a 32-dimensional input feature vector, a K-nearest neighbor classifier achieved an error rate of 1.2±0.4% in discriminating among participants. These results indicate that writers had unique grip shape kinetics that were repeatable over time but distinct from those of other participants. The topographic analysis of grip kinetics may inform the development of personalized interventions or customizable grips in clinical and industrial applications, respectively.

  14. Grasping an augmented object to analyse manipulative force control.

    Science.gov (United States)

    Kawai, Satoru; Summers, Valerie A; Mackenzie, Christine L; Ivens, Chris J; Yamamoto, Takashi

    2002-12-15

    Augmented reality allows changes to be made to the visual perception of object size even while the tangible components remain completely unaltered. It was, therefore, utilized in a study whose results are being reported here to provide the proper environment required to thoroughly observe the exact effect that visual change to object size had on programming fingertip forces when objects were lifted with a precision grip. Twenty-one participants performed repeated lifts of an identical grip apparatus to a height of 20 mm, maintained each lift for 8 seconds, and then replaced the grip apparatus on the table. While all other factors of the grip apparatus remained unchanged, visual appearance was altered graphically in a 3-D augmented environment. The grip apparatus measured grip and load forces independently. Grip and load forces demonstrated significant rates of increase as well as peak forces as the size of graphical images increased; an aspect that occurred in spite of the fact that extraneous haptic information remained constant throughout the trials. By indicating a human tendency to rely - even unconsciously - on visual input to program the forces in the initial lifting phase, this finding provides further confirmation of previous research findings obtained in the physical environment; including the possibility of extraneous haptic effects (Gordon et al. 1991a, Mon-Williams and Murray 2000, Kawai et al. 2000). The present results also suggest that existing knowledge concerning human manipulation tasks in the physical world may be applied to an augmented environment where the physical objects are enhanced by computer generated visual components.

  15. Anticipatory planning and control of grasp positions and forces for dexterous two-digit manipulation.

    Science.gov (United States)

    Fu, Qiushi; Zhang, Wei; Santello, Marco

    2010-07-07

    Dexterous object manipulation requires anticipatory control of digit positions and forces. Despite extensive studies on sensorimotor learning of digit forces, how humans learn to coordinate digit positions and forces has never been addressed. Furthermore, the functional role of anticipatory modulation of digit placement to object properties remains to be investigated. We addressed these questions by asking human subjects (12 females, 12 males) to grasp and lift an inverted T-shaped object using precision grip at constrained or self-chosen locations. The task requirement was to minimize object roll during lift. When digit position was not constrained, subjects could have implemented many equally valid digit position-force coordination patterns. However, choice of digit placement might also have resulted in large trial-to-trial variability of digit position, hence challenging the extent to which the CNS could have relied on sensorimotor memories for anticipatory control of digit forces. We hypothesized that subjects would modulate digit placement for optimal force distribution and digit forces as a function of variable digit positions. All subjects learned to minimize object roll within the first three trials, and the unconstrained device was associated with significantly smaller grip forces but larger variability of digit positions. Importantly, however, digit load force modulation compensated for position variability, thus ensuring consistent object roll minimization on each trial. This indicates that subjects learned object manipulation by integrating sensorimotor memories with sensory feedback about digit positions. These results are discussed in the context of motor equivalence and sensorimotor integration of grasp kinematics and kinetics.

  16. Hand-grip isometric strength in judo

    Directory of Open Access Journals (Sweden)

    Juan G Bonitch-Góngora

    2014-02-01

    Full Text Available The grip is an important technical and tactical aspect through which the judokas dominate the adversary, hindering the application of appropriate techniques and favoring their own attack. The judokas must have high levels of isometric force and endurance to this type of force on the gripping muscles of the forearms, as one of the key aspects for success. This article reviews the grip muscular strength and endurance profiles of judokas of different groups (gender, age and competitive level. In general, the peak isometric strength of elite judokas has not changed in the last 40 years and is similar to that reached by non-elite judokas or even registered in large populations. This indicate that the evaluation of the isometric hand grip endurance may be a more relevant parameter than the peak isometric force in judokas, as during the bouts the grip must be maintained for relatively long periods of time and the maximum force cannot be maintained for long. However there are few studies on the ability to resist successive isometric handgrip stress in judokas.

  17. Systems and Methods for Gravity-Independent Gripping and Drilling

    Science.gov (United States)

    Parness, Aaron (Inventor); Frost, Matthew A. (Inventor); Thatte, Nitish (Inventor); King, Jonathan P. (Inventor)

    2016-01-01

    Systems and methods for gravity independent gripping and drilling are described. The gripping device can also comprise a drill or sampling devices for drilling and/or sampling in microgravity environments, or on vertical or inverted surfaces in environments where gravity is present. A robotic system can be connected with the gripping and drilling devices via an ankle interface adapted to distribute the forces realized from the robotic system.

  18. Control of finger forces during fast, slow and moderate rotational hand movements.

    Science.gov (United States)

    Kazemi, Hamed; Kearney, Robert E; Milner, Theodore E

    2014-01-01

    The goal of this study was to investigate the effect of speed on patterns of grip forces during twisting movement involving forearm supination against a torsional load (combined elastic and inertial load). For slow and moderate speed rotations, the grip force increased linearly with load torque. However, for fast rotations in which the contribution of the inertia to load torque was significantly greater than slower movements, the grip force-load torque relationship could be segmented into two phases: a linear ascending phase corresponding to the acceleration part of the movement followed by a plateau during deceleration. That is, during the acceleration phase, the grip force accurately tracked the combined elastic and inertial load. However, the coupling between grip force and load torque was not consistent during the deceleration phase of the movement. In addition, as speed increased, both the position and the force profiles became smoother. No differences in the baseline grip force, safety margin to secure the grasp during hold phase or the overall change in grip force were observed across different speeds.

  19. Solid state controller three axes controller

    Science.gov (United States)

    Bailey, C. L., Jr. (Inventor)

    1973-01-01

    The reported flight controller features a handle grip which is mounted on a longitudinally extending control element. The handle grip is pivotally mounted on the control element about a pitch axis which is perpendicular to the longitudinal axis through the control element. The pivotal mounting includes a resilient force mounting mechanism which centers the grip relative to the control element. Rotation of the handle grip produces a direct rotation of a transducer element in a transducer which provides an electrical indication of the rotative movement about three mutually perpendicular axes.

  20. Effect of cervical vs. thoracic spinal manipulation on peripheral neural features and grip strength in subjects with chronic mechanical neck pain: a randomized controlled trial.

    Science.gov (United States)

    Bautista-Aguirre, Francisco; Oliva-Pascual-Vaca, Ángel; Heredia-Rizo, Alberto M; Boscá-Gandía, Juan J; Ricard, François; Rodriguez-Blanco, Cleofás

    2017-06-01

    Cervical and thoracic spinal manipulative therapy has shown positive impact for relief of pain and improve function in non-specific mechanical neck pain. Several attempts have been made to compare their effectiveness although previous studies lacked a control group, assessed acute neck pain or combined thrust and non-thrust techniques. To compare the immediate effects of cervical and thoracic spinal thrust manipulations on mechanosensitivity of upper limb nerve trunks and grip strength in patients with chronic non-specific mechanical neck pain. Randomized, single-blinded, controlled clinical trial. Private physiotherapy clinical consultancy. Eighty-eight subjects (32.09±6.05 years; 72.7% females) suffering neck pain (grades I or II) of at least 12 weeks of duration. Participants were distributed into three groups: 1) cervical group (N.=28); 2) thoracic group (N.=30); and 3) control group (N.=30). One treatment session consisting of applying a high-velocity low-amplitude spinal thrust technique over the lower cervical spine (C7) or the upper thoracic spine (T3) was performed, while the control group received a sham-manual contact. Measurements were taken at baseline and after intervention of the pressure pain threshold over the median, ulnar and radial nerves. Secondary measures included assessing free-pain grip strength with a hydraulic dynamometer. No statistically significant differences were observed when comparing between-groups in any of the outcome measures (P>0.05). Those who received thrust techniques, regardless of the manipulated area, reported an immediate increase in mechanosensitivity over the radial (both sides) and left ulnar nerve trunks (Ppain perception over the radial nerve also improved (P≤0.025). Low-cervical and upper-thoracic thrust manipulation is no more effective than placebo to induce immediate changes on mechanosensitivity of upper limb nerve trunks and grip strength in patients with chronic non-specific mechanical neck pain. A single

  1. Closed-loop control of grasping with a myoelectric hand prosthesis: which are the relevant feedback variables for force control?

    Science.gov (United States)

    Ninu, Andrei; Dosen, Strahinja; Muceli, Silvia; Rattay, Frank; Dietl, Hans; Farina, Dario

    2014-09-01

    In closed-loop control of grasping by hand prostheses, the feedback information sent to the user is usually the actual controlled variable, i.e., the grasp force. Although this choice is intuitive and logical, the force production is only the last step in the process of grasping. Therefore, this study evaluated the performance in controlling grasp strength using a hand prosthesis operated through a complete grasping sequence while varying the feedback variables (e.g., closing velocity, grasping force), which were provided to the user visually or through vibrotactile stimulation. The experiments were conducted on 13 volunteers who controlled the Otto Bock Sensor Hand Speed prosthesis. Results showed that vibrotactile patterns were able to replace the visual feedback. Interestingly, the experiments demonstrated that direct force feedback was not essential for the control of grasping force. The subjects were indeed able to control the grip strength, predictively, by estimating the grasping force from the prosthesis velocity of closing. Therefore, grasping without explicit force feedback is not completely blind, contrary to what is usually assumed. In our study we analyzed grasping with a specific prosthetic device, but the outcomes are also applicable for other devices, with one or more degrees-of-freedom. The necessary condition is that the electromyography (EMG) signal directly and proportionally controls the velocity/grasp force of the hand, which is a common approach among EMG controlled prosthetic devices. The results provide important indications on the design of closed-loop EMG controlled prosthetic systems.

  2. Hand grip strength

    DEFF Research Database (Denmark)

    Frederiksen, Henrik; Gaist, David; Petersen, Hans Christian

    2002-01-01

    in life is a major problem in terms of prevalence, morbidity, functional limitations, and quality of life. It is therefore of interest to find a phenotype reflecting physical functioning which has a relatively high heritability and which can be measured in large samples. Hand grip strength is known......-55%). A powerful design to detect genes associated with a phenotype is obtained using the extreme discordant and concordant sib pairs, of whom 28 and 77 dizygotic twin pairs, respectively, were found in this study. Hence grip strength is a suitable phenotype for identifying genetic variants of importance to mid...

  3. Precision grip in congenital and acquired hemiparesis: similarities in impairments and implications for neurorehabilitation - review

    Directory of Open Access Journals (Sweden)

    Yannick eBleyenheuft

    2014-06-01

    Full Text Available Background: Patients with congenital and acquired hemiparesis incur long-term functional deficits, among which the loss of prehension that may impact their functional independence. Identifying, understanding and comparing the underlying mechanisms of prehension impairments represent an opportunity to better adapt neurorehabilitationObjective: The present review aims to provide a better understanding of precision grip deficits in congenital and acquired hemiparesis and to determine whether the severity and type of fine motor control impairments depend on whether or not the lesions are congenital or acquired in adulthood. Methods: Using combinations of the following key words: fingertip force, grip force, precision grip, cerebral palsy, stroke, pubmed and Scopus databases were used to search studies from 1984 to 2013. Results: Individuals with both congenital and acquired hemiparesis were able to some extent to use anticipatory motor control in precision grip tasks, even if this control was impaired in the paretic hand. In both congenital or acquired hemiparesis, the ability to plan efficient anticipatory motor control when the less-affected hand is used provides a possibility to remediate impairments in anticipatory motor control of the paretic hand. Conclusion: Surprisingly we observed very few differences between the results of studies in children with congenital hemiplegia and stroke patients. We suggest that the underlying specific strategies of neurorehabilitation developed for each one could benefit the other.

  4. Automated force controller for amplitude modulation atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Miyagi, Atsushi, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr; Scheuring, Simon, E-mail: atsushi.miyagi@inserm.fr, E-mail: simon.scheuring@inserm.fr [U1006 INSERM, Université Aix-Marseille, Parc Scientifique et Technologique de Luminy, 163 Avenue de Luminy, 13009 Marseille (France)

    2016-05-15

    Atomic Force Microscopy (AFM) is widely used in physics, chemistry, and biology to analyze the topography of a sample at nanometer resolution. Controlling precisely the force applied by the AFM tip to the sample is a prerequisite for faithful and reproducible imaging. In amplitude modulation (oscillating) mode AFM, the applied force depends on the free and the setpoint amplitudes of the cantilever oscillation. Therefore, for keeping the applied force constant, not only the setpoint amplitude but also the free amplitude must be kept constant. While the AFM user defines the setpoint amplitude, the free amplitude is typically subject to uncontrollable drift, and hence, unfortunately, the real applied force is permanently drifting during an experiment. This is particularly harmful in biological sciences where increased force destroys the soft biological matter. Here, we have developed a strategy and an electronic circuit that analyzes permanently the free amplitude of oscillation and readjusts the excitation to maintain the free amplitude constant. As a consequence, the real applied force is permanently and automatically controlled with picoNewton precision. With this circuit associated to a high-speed AFM, we illustrate the power of the development through imaging over long-duration and at various forces. The development is applicable for all AFMs and will widen the applicability of AFM to a larger range of samples and to a larger range of (non-specialist) users. Furthermore, from controlled force imaging experiments, the interaction strength between biomolecules can be analyzed.

  5. GRIP CAMPAIGN REPORTS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Campaign Reports dataset consists of various reports filed by scientists during the GRIP campaign which took place 8/15/2010 - 9/30/2010; however, several...

  6. Age and Sex Differences in Controlled Force Exertion Measured by a Computing Bar Chart Target-Pursuit System

    Science.gov (United States)

    Nagasawa, Yoshinori; Demura, Shinichi

    2009-01-01

    This study aimed to examine the age and sex differences in controlled force exertion measured by the bar chart display in 207 males (age 42.1 [plus or minus] 19.8 years) and 249 females (age 41.7 [plus or minus] 19.1 years) aged 15 to 86 years. The subjects matched their submaximal grip strength to changing demand values, which appeared as a…

  7. Grip type and task goal modify reach-to-grasp performance in post-stroke hemiparesis

    Science.gov (United States)

    Schaefer, Sydney Y.; DeJong, Stacey L.; Cherry, Kendra M.; Lang, Catherine E.

    2011-01-01

    This study investigated whether grip type and/or task goal influenced reaching and grasping performance in post-stroke hemiparesis. Sixteen adults with post-stroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared to the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment. PMID:22357103

  8. Short-Term Effects of Whole-Body Vibration Combined with Task-Related Training on Upper Extremity Function, Spasticity, and Grip Strength in Subjects with Poststroke Hemiplegia: A Pilot Randomized Controlled Trial.

    Science.gov (United States)

    Lee, Jung-Sun; Kim, Chang-Yong; Kim, Hyeong-Dong

    2016-08-01

    The aim of this study was to determine the effect of whole-body vibration training combined with task-related training on arm function, spasticity, and grip strength in subjects with poststroke hemiplegia. Forty-five subjects with poststroke were randomly allocated to 3 groups, each with 15 subjects as follows: control group, whole-body vibration group, and whole-body vibration plus task-related training group. Outcome was evaluated by clinical evaluation and measurements of the grip strength before and 4 weeks after intervention. Our results show that there was a significantly greater increase in the Fugl-Meyer scale, maximal grip strength of the affected hand, and grip strength normalized to the less affected hand in subjects undergoing the whole-body vibration training compared with the control group after the test. Furthermore, there was a significantly greater increase in the Wolf motor function test and a decrease in the modified Ashworth spasticity total scores in subjects who underwent whole-body vibration plus task-related training compared with those in the other 2 groups after the test. The findings indicate that the use of whole-body vibration training combined with task-related training has more benefits on the improvement of arm function, spasticity, and maximal grip strength than conventional upper limb training alone or with whole-body vibration in people with poststroke hemiplegia.

  9. Why pens have rubbery grips

    Science.gov (United States)

    Dzidek, Brygida; Bochereau, Séréna; Johnson, Simon A.; Hayward, Vincent; Adams, Michael J.

    2017-10-01

    The process by which human fingers gives rise to stable contacts with smooth, hard objects is surprisingly slow. Using high-resolution imaging, we found that, when pressed against glass, the actual contact made by finger pad ridges evolved over time following a first-order kinetics relationship. This evolution was the result of a two-stage coalescence process of microscopic junctions made between the keratin of the stratum corneum of the skin and the glass surface. This process was driven by the secretion of moisture from the sweat glands, since increased hydration in stratum corneum causes it to become softer. Saturation was typically reached within 20 s of loading the contact, regardless of the initial moisture state of the finger and of the normal force applied. Hence, the gross contact area, frequently used as a benchmark quantity in grip and perceptual studies, is a poor reflection of the actual contact mechanics that take place between human fingers and smooth, impermeable surfaces. In contrast, the formation of a steady-state contact area is almost instantaneous if the counter surface is soft relative to keratin in a dry state. It is for this reason that elastomers are commonly used to coat grip surfaces.

  10. Studying hand grip strength development among students who have taken tennis and massage courses

    Directory of Open Access Journals (Sweden)

    Erzeybek Mustafa Said

    2017-01-01

    Full Text Available In this study, the finger and hand force developments of the students who have taken selective/applied Tennis and Massage courses at the University have been examined. From the students of the Department of Physical Education and Sport, 19 healthy females and 73 healthy males (age = 21.25 ± 1.55 years (average ± SD who have taken selective Tennis courses;51 healthy males (age = 22.00 ± 1.04 years (average ± SD who have taken Massage courses; and as the control group,16 healthy womenand50 healthy males(age = 21.72 ± 1.47 years (average ± SD have been participated to the study. The age, length, body weight, grip strength of both hands as well as the finger grip strength of the subjects have been recorded. The course schedule has been set as once a week four hours practice for both tennis and massage. Two weeks of the education and training program that takes twelve weeks in total were assigned for theoretical classes. The remaining period of ten weeks was for practice classes and the measurements were performed before and after this ten weeks period. The hand grip strength measurement has been carried out with a Takkei branded hand dynamometer whereas for the measurement of the finger grip strength, a Baseline branded pinch meter has been used. For both the pre-test and final test of the finger grip and hand grip strength measurements, the paired sample t test has been used in terms of in-group comparisons, whereas for the inter-group comparisons, one-way ANOVA has been used. For the significant F values, post hoc Tukey test has been used. The right hand and the left hand grip values of both test groups as well as the values of the control group have been significantly increased between the pre-test and final test. Particularly, preferring the exercises that improve the hand and finger grip strengths would enable a better racket handle grip as well as an improved shot efficiency for tennis. This would also enable masseurs/masseuses to apply

  11. Tensile testing grips are easily assembled under liquid nitrogen

    Science.gov (United States)

    Skalka, R. J.; Vandergrift, E. F.

    1967-01-01

    Split-screw grips for tensile testing provide uniform loading on the specimen shoulders. Holes in the heads enable the screws and specimen to be threaded as an assembly into a grip body, closely controlled guides and seats afford positive seating, and precision machining of mating surfaces minimizes misalignment effects.

  12. Road grip test in Arjeplog

    OpenAIRE

    Engström, Niclas; Andrén, Henrik; Nybacka, Mikael; Fransson, Lennart; Larsson, Roland

    2008-01-01

    The Swedish road administration sees a need to improve the road grip estimation capacity for the Swedish road system. The challenge is to find methods to measure road grip fast and reliable. There where six different system types at the tests in Arjeplog, three continuous, two system measuring road grip through deceleration and one system based on GPS and accelerometers. Two system types used air craft runway tires. The other systems used either studded winter tires or friction winter tires. ...

  13. Enter the Gripping Beast

    DEFF Research Database (Denmark)

    Sindbæk, Søren Michael

    2012-01-01

    on innovations. Mostly, however, the time-resolution of archaeological data is too coarse-grained to allow us to grasp this potential to the full. In the period c. AD 790-850 a distinctly new artistic motif, the Gripping Beast, emerged in Scandinavia. A series of narrowly dated contexts provide anchor points......, which allows us to chart this innovation process and to point out some of the locations where this development took place; the reception of the mew motif is traced in grave finds across Scandinavia. This allows us to follow an early medieval innovation through the human-material interactions of an actor-network....

  14. Cutaneous mechanisms of isometric ankle force control

    DEFF Research Database (Denmark)

    Choi, Julia T; Jensen, Jesper Lundbye; Leukel, Christian

    2013-01-01

    The sense of force is critical in the control of movement and posture. Multiple factors influence our perception of exerted force, including inputs from cutaneous afferents, muscle afferents and central commands. Here, we studied the influence of cutaneous feedback on the control of ankle force...... of transient stimulation on force error were greater when compared to continuous stimulation and lidocaine injection. Position-matching performance was unaffected by peroneal nerve or plantar nerve stimulation. Our results show that cutaneous feedback plays a role in the control of force output at the ankle...... joint. Understanding how the nervous system normally uses cutaneous feedback in motor control will help us identify which functional aspects are impaired in aging and neurological diseases....

  15. A firm political grip on the market

    International Nuclear Information System (INIS)

    Bakken, Stein Arne

    2003-01-01

    In Norway, there is a strong political grip on the energy supply industry. The market is going to play a marginal role. The article deals with three scenarios for what the Norwegian energy supply might look like in 2005 as envisaged by a group of researchers in a comprehensive project carried out by ECON. The first scenario, ''The Market Place'', shows the development of the energy supply from regulation to a free market in the wake of the new Energy Act. According to this scenario, by 2005 the market should be well established as a form of control. The second scenario, ''The Norwegian Way'', shows the way of the energy supply from a free market to regulation. The third scenario is ''The Field of Force'' and shows how the energy supply develops into a strong energy industrial complex; this is the scenario that definitely has not come true. The most likely scenario to come true in ten years is probably a mixture of ''The Market Place'' and ''The Norwegian Way'' with an emphasis on the latter. The trend is clearly for increased political control

  16. Telerobotic Control Architecture Including Force-Reflection

    National Research Council Canada - National Science Library

    Murphy, Mark

    1998-01-01

    This report describes the implementation of a telerobotic control architecture to manipulate a standard six-degree-of-freedom robot via a unique seven-degree-of-freedom force-reflecting exoskeleton...

  17. Computational model of precision grip in Parkinson’s disease: A Utility based approach

    Directory of Open Access Journals (Sweden)

    Ankur eGupta

    2013-12-01

    Full Text Available We propose a computational model of Precision Grip (PG performance in normal subjects and Parkinson’s Disease (PD patients. Prior studies on grip force generation in PD patients show an increase in grip force during ON medication and an increase in the variability of the grip force during OFF medication (Fellows et al 1998; Ingvarsson et al 1997. Changes in grip force generation in dopamine-deficient PD conditions strongly suggest contribution of the Basal Ganglia, a deep brain system having a crucial role in translating dopamine signals to decision making. The present approach is to treat the problem of modeling grip force generation as a problem of action selection, which is one of the key functions of the Basal Ganglia. The model consists of two components: 1 the sensory-motor loop component, and 2 the Basal Ganglia component. The sensory-motor loop component converts a reference position and a reference grip force, into lift force and grip force profiles, respectively. These two forces cooperate in grip-lifting a load. The sensory-motor loop component also includes a plant model that represents the interaction between two fingers involved in PG, and the object to be lifted. The Basal Ganglia component is modeled using Reinforcement Learning with the significant difference that the action selection is performed using utility distribution instead of using purely Value-based distribution, thereby incorporating risk-based decision making. The proposed model is able to account for the precision grip results from normal and PD patients accurately (Fellows et. al. 1998; Ingvarsson et. al. 1997. To our knowledge the model is the first model of precision grip in PD conditions.

  18. Handling device with grips operated by a servo-motor

    International Nuclear Information System (INIS)

    Sgarbi, F.; Detriche, J.M.

    1990-01-01

    On grip jaws are set up a detection circuit which allows the rocking of the control system from a control system in position to a control system in clamping strain when an object is held, and then which allows to use them by turns in order to keep only their advantages. A larger light touch handling is obtained. The application of this grip is recommended to catch brittle objects (for handicapped persons by example) [fr

  19. Controlling Casimir force via coherent driving field

    Science.gov (United States)

    Ahmad, Rashid; Abbas, Muqaddar; Ahmad, Iftikhar; Qamar, Sajid

    2016-04-01

    A four level atom-field configuration is used to investigate the coherent control of Casimir force between two identical plates made up of chiral atomic media and separated by vacuum of width d. The electromagnetic chirality-induced negative refraction is obtained via atomic coherence. The behavior of Casimir force is investigated using Casimir-Lifshitz formula. It is noticed that Casimir force can be switched from repulsive to attractive and vice versa via coherent control of the driving field. This switching feature provides new possibilities of using the repulsive Casimir force in the development of new emerging technologies, such as, micro-electro-mechanical and nano-electro-mechanical systems, i.e., MEMS and NEMS, respectively.

  20. Acoustic radiation force control: Pulsating spherical carriers.

    Science.gov (United States)

    Rajabi, Majid; Mojahed, Alireza

    2018-02-01

    power supply for distinct cases of zero, negative and positive radiation force states along with the frequency dependent asymmetry index. In addition, considering the effect of phase difference between the incident wave field and the pulsating object, and its possible variation with respect to spatial position of object, some practical points about the spatial average of generated radiation force, the optimal state of operation, the stability of zero radiation force states and the possibly of precise motion control are discussed. This work would extend the novel concept of smart carriers to and may be helpful for robust single-beam acoustic handling techniques. Furthermore, the shown capability of precise motion control may be considered as a new way toward smart acoustic driven micro-mechanisms and micro-machines. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Grip strength, postural control, and functional leg power in a representative cohort of British men and women: associations with physical activity, health status, and socioeconomic conditions.

    Science.gov (United States)

    Kuh, Diana; Bassey, E Joan; Butterworth, Suzanne; Hardy, Rebecca; Wadsworth, Michael E J

    2005-02-01

    Understanding the health, behavioral, and social factors that influence physical performance in midlife may provide clues to the origins of frailty in old age and the future health of elderly populations. The authors evaluated muscle strength, postural control, and chair rise performance in a large representative prospective cohort of 53-year-old British men and women in relation to functional limitations, body size, health and activity, and socioeconomic conditions. Nurses interviewed 2984 men and women in their own homes in England, Scotland, and Wales and conducted physical examinations in 2956 of them. Objective measures were height, weight, and three physical performance tests: handgrip strength, one-legged standing balance time, and time to complete 10 chair rises. Functional limitations (difficulties walking, stair climbing, gripping, and falls), health status, physical activity, and social class were obtained using a structured questionnaire. Those with the worst scores on the physical performance tests had higher rates of functional limitations for both upper and lower limbs. Women had much weaker handgrip strength, somewhat poorer balance time, and only slightly poorer chair rise time compared with men. In women, health problems and low levels of physical activity contributed to poor physical performance on all three measures. In men, physical activity was the predominant influence. Heavier weight and poorer socioeconomic conditions contributed to poorer balance and chair rise times. In this representative middle-aged group, physical performance levels varied widely, and women were seriously disadvantaged compared with men. In general, physical performance was worse for men and women living in poorer socioeconomic conditions with greater body weight, poorer health status, and inactive lifestyles. These findings support recommendations for controlling excess body weight, effective health interventions, and the maintenance of active lifestyles during aging.

  2. Grip for sawing round timber

    Energy Technology Data Exchange (ETDEWEB)

    1982-07-01

    This paper describes a device development at Gedling Colliery, Nottinghamshire Area, United Kingdom. It is a gripping attachment, designed to overcome the safety hazards involved in cross cutting timbers with a circular saw.

  3. Quantifying feedforward control: a linear scaling model for fingertip forces and object weight.

    Science.gov (United States)

    Lu, Ying; Bilaloglu, Seda; Aluru, Viswanath; Raghavan, Preeti

    2015-07-01

    The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feedforward control, and it is thought to occur due to the formation of internal representations of the object's properties. The control of fingertip forces to objects of different weights has been studied extensively by using a custom-made grip device instrumented with force sensors. Feedforward control is measured by the rate of change of the vertical (load) force before the object is lifted. However, the precise relationship between the rate of change of load force and object weight and how it varies across healthy individuals in a population is not clearly understood. Using sets of 10 different weights, we have shown that there is a log-linear relationship between the fingertip load force rates and weight among neurologically intact individuals. We found that after one practice lift, as the weight increased, the peak load force rate (PLFR) increased by a fixed percentage, and this proportionality was common among the healthy subjects. However, at any given weight, the level of PLFR varied across individuals and was related to the efficiency of the muscles involved in lifting the object, in this case the wrist and finger extensor muscles. These results quantify feedforward control during grasp and lift among healthy individuals and provide new benchmarks to interpret data from neurologically impaired populations as well as a means to assess the effect of interventions on restoration of feedforward control and its relationship to muscular control. Copyright © 2015 the American Physiological Society.

  4. Mind Your Grip: Even Usual Dexterous Manipulation Requires High Level Cognition

    Directory of Open Access Journals (Sweden)

    Erwan Guillery

    2017-11-01

    Full Text Available Simultaneous execution of cognitive and sensorimotor tasks is critical in daily life. Here, we examined whether dexterous manipulation, a highly habitual and seemingly automatic behavior, involves high order cognitive functions. Specifically, we explored the impact of reducing available cognitive resources on the performance of a precision grip-lift task in healthy participants of three age groups (18–30, 30–60 and 60–75 years. Participants performed a motor task in isolation (M, in combination with a low-load cognitive task (M + L, and in combination with a high-load cognitive task (M + H. The motor task consisted in grasping, lifting and holding an apparatus instrumented with force sensors to monitor motor task performance. In the cognitive task, a list of letters was shown briefly before the motor task. After completing the motor task, one letter of the list was shown, and participants reported the following letter of the list. In M + L, letters in the list followed the alphabetical order. In M + H, letters were presented in random order. Performing the high-load task thus required maintaining information in working memory. Temporal and dynamic parameters of grip and lift forces were compared across conditions. During the cognitive tasks, there was a significant alteration of movement initiation and a significant increase of grip force (GF throughout the grip-lift task. There was no interaction with “age”. Our results demonstrate that planning and the on-line control of dexterous manipulation is not an automatic behavior and, instead, that it interacts with high-level cognitive processes such as those involved in working memory.

  5. Customization, control, and characterization of a commercial haptic device for high-fidelity rendering of weak forces.

    Science.gov (United States)

    Gurari, Netta; Baud-Bovy, Gabriel

    2014-09-30

    The emergence of commercial haptic devices offers new research opportunities to enhance our understanding of the human sensory-motor system. Yet, commercial device capabilities have limitations which need to be addressed. This paper describes the customization of a commercial force feedback device for displaying forces with a precision that exceeds the human force perception threshold. The device was outfitted with a multi-axis force sensor and closed-loop controlled to improve its transparency. Additionally, two force sensing resistors were attached to the device to measure grip force. Force errors were modeled in the frequency- and time-domain to identify contributions from the mass, viscous friction, and Coulomb friction during open- and closed-loop control. The effect of user interaction on system stability was assessed in the context of a user study which aimed to measure force perceptual thresholds. Findings based on 15 participants demonstrate that the system maintains stability when rendering forces ranging from 0-0.20 N, with an average maximum absolute force error of 0.041 ± 0.013 N. Modeling the force errors revealed that Coulomb friction and inertia were the main contributors to force distortions during respectively slow and fast motions. Existing commercial force feedback devices cannot render forces with the required precision for certain testing scenarios. Building on existing robotics work, this paper shows how a device can be customized to make it reliable for studying the perception of weak forces. The customized and closed-loop controlled device is suitable for measuring force perceptual thresholds. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Robust Force Control of Series Elastic Actuators

    Directory of Open Access Journals (Sweden)

    Andrea Calanca

    2014-07-01

    Full Text Available Force-controlled series elastic actuators (SEA are widely used in novel human-robot interaction (HRI applications, such as assistive and rehabilitation robotics. These systems are characterized by the presence of the “human in the loop”, so that control response and stability depend on uncertain human dynamics, including reflexes and voluntary forces. This paper proposes a force control approach that guarantees the stability and robustness of the coupled human-robot system, based on sliding-mode control (SMC, considering the human dynamics as a disturbance to reject. We propose a chattering free solution that employs simple task models to obtain high performance, comparable with second order solutions. Theoretical stability is proven within the sliding mode framework, and predictability is reached by avoiding the reaching phase by design. Furthermore, safety is introduced by a proper design of the sliding surface. The practical feasibility of the approach is shown using an SEA prototype coupled with a human impedance in severe stress tests. To show the quality of the approach, we report a comparison with state-of-the-art second order SMC, passivity-based control and adaptive control solutions.

  7. THE DEMOCRATIC CONTROL OF MILITARY FORCES

    Directory of Open Access Journals (Sweden)

    Smail Oštraković

    2011-04-01

    Full Text Available The transition requirement for post communism countries, especially the part that is about military forces is to establish those civil-military relation that will have prepared projects for awareness evolving of society and military about necessity of democratic control over military sector of country through development of many different communication forms and shapes. Before everything, it means the entire freedom and independence of media at access to military forces as the topic and subject of its interests and also the organization of public military communication system as integral part of information-communication system in society

  8. Output control of da Vinci surgical system's surgical graspers.

    Science.gov (United States)

    Johnson, Paul J; Schmidt, David E; Duvvuri, Umamaheswar

    2014-01-01

    The number of robot-assisted surgeries performed with the da Vinci surgical system has increased significantly over the past decade. The articulating movements of the robotic surgical grasper are controlled by grip controls at the master console. The user interface has been implicated as one contributing factor in surgical grasping errors. The goal of our study was to characterize and evaluate the user interface of the da Vinci surgical system in controlling surgical graspers. An angular manipulator with force sensors was used to increment the grip control angle as grasper output angles were measured. Input force at the grip control was simultaneously measured throughout the range of motion. Pressure film was used to assess the maximum grasping force achievable with the endoscopic grasping tool. The da Vinci robot's grip control angular input has a nonproportional relationship with the grasper instrument output. The grip control mechanism presents an intrinsic resistant force to the surgeon's fingertips and provides no haptic feedback. The da Vinci Maryland graspers are capable of applying up to 5.1 MPa of local pressure. The angular and force input at the grip control of the da Vinci robot's surgical graspers is nonproportional to the grasper instrument's output. Understanding the true relationship of the grip control input to grasper instrument output may help surgeons understand how to better control the surgical graspers and promote fewer grasping errors. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Thimble grip fuel assembly handling tool

    International Nuclear Information System (INIS)

    Salton, R.B.; Hornak, L.P.; Marshall, J.R.; Meuschke, R.E.

    1989-01-01

    This patent describes an apparatus for lifting a fuel assembly of a nuclear reactor. The fuel assembly consists of a top nozzle and control rod guide tubes. The apparatus having a gripping means comprised of: a life plate, an actuating plate having a plurality of apertures, the actuating plate disposed in spaced relationship below the lift plate and vertically movable relative thereto; gripping members operably associated with the lift and actuating plates, the gripping members comprising: (a) a vertical rod fixedly secured near its top end to the lift plate and projecting downward therefrom through an associated aperture in the actuating plate, the rod having a first frustoconical surface formed near its lower end, (b) a generally cylindrical, elastically deformable vertical sleeve having a bore therethrough with a first inner diameter, the sleeve having a first bevelled inside surface near the top end and a second bevelled inside surface at the bottom end of the sleeve, and (c) a vertical gripper actuator disposed about the rod

  10. Changes in pain, dysfunction, and grip strength of patients with acute lateral epicondylitis caused by frequency of physical therapy: a randomized controlled trial.

    Science.gov (United States)

    Lee, Soyoung; Ko, Youngjun; Lee, Wanhee

    2014-07-01

    [Purpose] The purpose of this study was to investigate the changes in pain, dysfunction, and grip strength of patients with acute lateral epicondylitis and to suggest the appropriate treatment frequency and period. [Subjects] The subjects were divided into three: 2 days per week group (n=12), 3 days per week group (n=15), and 6 days per week group (n=13). [Methods] All groups received conventional physical therapy for 40 minutes and therapeutic exercises for 20 minutes per session during 6 weeks. The outcome measurements were the visual analogue scale (VAS), Patient-Rated Tennis Elbow Evaluation (PRTEE), and grip strength. [Results] The results of this study were as follows: at 3 weeks, there were no significant differences in VAS and PRTEE in the 3 groups, but at 6 weeks, 6 days per week group significantly decreased these two outcomes. Grip strength was significantly increased in 3 and 6 days per week groups at 6 weeks. [Conclusion] In conclusion, physical therapy is needed 3 days per week for 3 weeks in patients with acute lateral epicondylitis. After 3 weeks, 6 days per week is the most effective treatment frequency.

  11. Hand grip strength in patients with chronic obstructive pulmonary disease

    Directory of Open Access Journals (Sweden)

    Jeong M

    2017-08-01

    Full Text Available Moa Jeong,1 Hyung Koo Kang,1 Pamela Song,2 Hye Kyeong Park,1 Hoon Jung,1 Sung-Soon Lee,1 Hyeon-Kyoung Koo1 1Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, 2Department of Neurology, Ilsan Paik Hospital, Inje University College of Medicine, Goyang, Republic of Korea Purpose: Hand grip strength (HGS is a simple way of predicting the risk of cardiovascular disease and all-cause mortality in the general population. However, the practical significance of grip strength in patients with COPD is uncertain. The aim of this study was to compare HGS between subjects with and without COPD and to evaluate its clinical relevance in patients with COPD by using a national survey.Methods: Data were collected from the Korean National Health and Nutrition Examination Survey. The study included 421 adults with COPD and 2,542 controls who completed questionnaires, spirometry, and a HGS test. HGS was compared between subjects with and without COPD, and the association between grip strength, lung function, and quality of life (QoL was evaluated.Results: The mean HGS was 33.3±9.1 kg in the COPD group and 29.9±9.5 kg in the non-COPD group; adjusted HGS was 30.9±0.33 kg and 30.9±0.11 kg, respectively (P=0.99. HGS was not related to forced vital capacity (β=0.04, P=0.70 or forced expiratory volume in 1 second (β=0.11, P=0.24 in multivariable analysis. HGS was independently associated with the EQ-5D index, but the relationship was stronger in the COPD group (β=0.30, P<0.001 than in the non-COPD group (β=0.21, P<0.001. The results were similar for each component of the EQ-5D, including mobility (β=-0.25, P<0.001, daily activity (β=-0.19, P=0.01, pain/discomfort (β=-0.32, P<0.001, and anxiety/depression (β=-0.16, P=0.01.Conclusion: HGS was not different between subjects with and without COPD, but was associated with QoL – including mobility, daily activity, pain/discomfort, and anxiety/depression – in patients with COPD. The

  12. Controller Synthesis for Periodically Forced Chaotic Systems

    Science.gov (United States)

    Basso, Michele; Genesio, Roberto; Giovanardi, Lorenzo

    Delayed feedback controllers are an appealing tool for stabilization of periodic orbits in chaotic systems. Despite their conceptual simplicity, specific and reliable design procedures are difficult to obtain, partly also because of their inherent infinite-dimensional structure. This chapter considers the use of finite dimensional linear time invariant controllers for stabilization of periodic solutions in a general class of sinusoidally forced nonlinear systems. For such controllers — which can be interpreted as rational approximations of the delayed ones — we provide a computationally attractive synthesis technique based on Linear Matrix Inequalities (LMIs), by mixing results concerning absolute stability of nonlinear systems and robustness of uncertain linear systems. The resulting controllers prove to be effective for chaos suppression in electronic circuits and systems, as shown by two different application examples.

  13. Interactive effects of music tempi and intensities on grip strength and subjective affect.

    Science.gov (United States)

    Karageorghis, C I; Cheek, P; Simpson, S D; Bigliassi, M

    2018-03-01

    Pretask music is widely used by athletes albeit there is scant empirical evidence to support its use. The present study extended a line of work into pretask music by examining the interactive effects of music tempo and intensity (volume) on the performance of a simple motor skill and subjective affect. A 2 × 2 within-subjects factorial design was employed with an additional no-music control, the scores from which were used as a covariate. A sample of 52 male athletes (M age  = 26.1 ± 4.8 years) was exposed to five conditions: fast/loud (126 bpm/80 dBA), fast/quiet (126 bpm/70 dBA), slow/loud (87 bpm/80 dBA), slow/quiet (87 bpm/70 dBA) music, and a no-music control. Dependent variables were grip strength, measured with a handgrip dynamometer, and subjective affect, assessed by use of the Affect Grid. The tempo and intensity components of music had interactive effects for grip strength but only main effects for subjective affect. Fast-tempo music played at a high intensity yielded the highest grip strength, while fast-tempo music played at a low-intensity resulted in much lower grip strength (M diff.  = -1.11 Force kg). For affective valence, there were main effects of tempo and intensity, with fast and loud music yielding the highest scores. For affective arousal, there was no difference between tempi although there was between intensities, with the high-intensity condition yielding higher scores. The present findings indicate the utility of fast/loud pretask music in enhancing affective valence and arousal in preparation for a simple or gross motor task. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. 14 CFR 23.155 - Elevator control force in maneuvers.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Elevator control force in maneuvers. 23.155 Section 23.155 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Controllability and Maneuverability § 23.155 Elevator control force in maneuvers. (a) The elevator control force...

  15. Development of isometric force and force control in children

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Westenberg, Y.; Duysens, J.E.J.

    2004-01-01

    Fifty-six children between 5 and 12 years of age and 15 adults performed a task (pressing on a lever with the index finger of the preferred hand), in which a force had to be maintained constant at five levels with on-line visual feedback. Since this is a simple isometric task, the hypothesis is that

  16. Development of isometric force and force control in children.

    NARCIS (Netherlands)

    Smits-Engelsman, B.C.M.; Westenberg, Y.; Duysens, J.E.J.

    2003-01-01

    Fifty-six children between 5 and 12 years of age and 15 adults performed a task (pressing on a lever with the index finger of the preferred hand), in which a force had to be maintained constant at five levels with on-line visual feedback. Since this is a simple isometric task, the hypothesis is that

  17. Correlation of force control with regional spinal DTI in patients with cervical spondylosis without signs of spinal cord injury on conventional MRI

    International Nuclear Information System (INIS)

    Lindberg, Paavel G.; Sanchez, Katherine; Rannou, Francois; Poiraudeau, Serge; Ozcan, Fidan; Feydy, Antoine; Maier, Marc A.

    2016-01-01

    The aim of this study was to investigate spinal cord structure in patients with cervical spondylosis where conventional MRI fails to reveal spinal cord damage. We performed a cross-sectional study of patients with cervical spondylosis without conventional MRI findings of spinal cord damage and healthy controls. Subjects were studied using spinal diffusion tensor imaging (DTI), precision grip and foot force-tracking tasks, and a clinical examination including assessment of neurological signs. A regional analysis of lateral and medial spinal white matter across multiple cervical levels (C1-C5) was performed. DTI revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the lateral spinal cord at the level of greatest compression (lowest Pavlov ratio) in patients (p < 0.05). Patients with spondylosis had greater error and longer release duration in both grip and foot force-tracking. Similar spinal cord deficits were present in patients without neurological signs. Increased error in grip and foot tracking (low accuracy) correlated with increased RD in the lateral spinal cord at the level of greatest compression (p ≤ 0.01). Spinal DTI can detect subtle spinal cord damage of functional relevance in cervical spondylosis, even in patients without signs on conventional T2-imaging and without neurological signs. (orig.)

  18. Correlation of force control with regional spinal DTI in patients with cervical spondylosis without signs of spinal cord injury on conventional MRI

    Energy Technology Data Exchange (ETDEWEB)

    Lindberg, Paavel G. [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Centre de Psychiatrie et Neurosciences, Inserm U894, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Descartes, Service de Radiologie B, APHP, CHU Cochin, Faculte de Medecine, Paris (France); Sanchez, Katherine; Rannou, Francois; Poiraudeau, Serge [Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Service de Medecine Physique et de Readaptation, APHP, CHU Cochin, Paris (France); INSERM U1153 Epidemiologie Clinique des Maladies Osteo-Articulaires, Paris (France); Ozcan, Fidan [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Feydy, Antoine [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Descartes, Service de Radiologie B, APHP, CHU Cochin, Faculte de Medecine, Paris (France); Maier, Marc A. [Universite Paris Descartes, Sorbonne Paris Cite, FR 3636 Neurosciences, Paris (France); Universite Paris Descartes, Sorbonne Paris Cite, Paris (France); Universite Paris Diderot, Sorbonne Paris Cite, Paris (France)

    2016-03-15

    The aim of this study was to investigate spinal cord structure in patients with cervical spondylosis where conventional MRI fails to reveal spinal cord damage. We performed a cross-sectional study of patients with cervical spondylosis without conventional MRI findings of spinal cord damage and healthy controls. Subjects were studied using spinal diffusion tensor imaging (DTI), precision grip and foot force-tracking tasks, and a clinical examination including assessment of neurological signs. A regional analysis of lateral and medial spinal white matter across multiple cervical levels (C1-C5) was performed. DTI revealed reduced fractional anisotropy (FA) and increased radial diffusivity (RD) in the lateral spinal cord at the level of greatest compression (lowest Pavlov ratio) in patients (p < 0.05). Patients with spondylosis had greater error and longer release duration in both grip and foot force-tracking. Similar spinal cord deficits were present in patients without neurological signs. Increased error in grip and foot tracking (low accuracy) correlated with increased RD in the lateral spinal cord at the level of greatest compression (p ≤ 0.01). Spinal DTI can detect subtle spinal cord damage of functional relevance in cervical spondylosis, even in patients without signs on conventional T2-imaging and without neurological signs. (orig.)

  19. Reference Values of Grip Strength, Prevalence of Low Grip Strength, and Factors Affecting Grip Strength Values in Chinese Adults.

    Science.gov (United States)

    Yu, Ruby; Ong, Sherlin; Cheung, Osbert; Leung, Jason; Woo, Jean

    2017-06-01

    The objectives of this study were to update the reference values of grip strength, to estimate the prevalence of low grip strength, and to examine the impact of different aspects of measurement protocol on grip strength values in Chinese adults. A cross-sectional survey of Chinese men (n = 714) and women (n = 4014) aged 18-102 years was undertaken in different community settings in Hong Kong. Grip strength was measured with a digital dynamometer (TKK 5401 Grip-D; Takei, Niigata, Japan). Low grip strength was defined as grip strength 2 standard deviations or more below the mean for young adults. The effects of measurement protocol on grip strength values were examined in a subsample of 45 men and women with repeated measures of grip strength taken with a hydraulic dynamometer (Baseline; Fabrication Enterprises Inc, Irvington, NY), using pair t-tests, intraclass correlation coefficient, and Bland and Altman plots. Grip strength was greater among men than among women (P values than the Baseline hydraulic dynamometer (P values were also observed when the measurement was performed with the elbow extended in a standing position, compared with that with the elbow flexed at 90° in a sitting position, using the same dynamometer (P values of grip strength and estimated the prevalence of low grip strength among Chinese adults spanning a wide age range. These findings might be useful for risk estimation and evaluation of interventions. However, grip strength measurements should be interpreted with caution, as grip strength values can be affected by type of dynamometer used, assessment posture, and elbow position. Copyright © 2017 AMDA – The Society for Post-Acute and Long-Term Care Medicine. Published by Elsevier Inc. All rights reserved.

  20. Finger pressure adjustments to various object configurations during precision grip in humans and monkeys.

    Science.gov (United States)

    Viaro, Riccardo; Tia, Banty; Coudé, Gino; Canto, Rosario; Oliynyk, Andriy; Salmas, Paola; Masia, Lorenzo; Sandini, Giulio; Fadiga, Luciano

    2017-06-01

    In this study, we recorded the pressure exerted onto an object by the index finger and the thumb of the preferred hand of 18 human subjects and either hand of two macaque monkeys during a precision grasping task. The to-be-grasped object was a custom-made device composed by two plates which could be variably oriented by a motorized system while keeping constant the size and thus grip dimension. The to-be-grasped plates were covered by an array of capacitive sensors to measure specific features of finger adaptation, namely pressure intensity and centroid location and displacement. Kinematic measurements demonstrated that for human subjects and for monkeys, different plate configurations did not affect wrist velocity and grip aperture during the reaching phase. Consistently, at the instant of fingers-plates contact, pressure centroids were clustered around the same point for all handle configurations. However, small pressure centroid displacements were specifically adopted for each configuration, indicating that both humans and monkeys can display finger adaptation during precision grip. Moreover, humans applied stronger thumb pressure intensity, performed less centroid displacement and required reduced adjustment time, as compared to monkeys. These pressure patterns remain similar when different load forces were required to pull the handle, as ascertained by additional measurements in humans. The present findings indicate that, although humans and monkeys share common features in motor control of grasping, they differ in the adjustment of fingertip pressure, probably because of skill and/or morphology divergences. Such a precision grip device may form the groundwork for future studies on prehension mechanisms. © 2017 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  1. Comprehension of handwriting development: Pen-grip kinetics in handwriting tasks and its relation to fine motor skills among school-age children.

    Science.gov (United States)

    Lin, Yu-Chen; Chao, Yen-Li; Wu, Shyi-Kuen; Lin, Ho-Hsio; Hsu, Chieh-Hsiang; Hsu, Hsiao-Man; Kuo, Li-Chieh

    2017-10-01

    Numerous tools have been developed to evaluate handwriting performances by analysing written products. However, few studies have directly investigated kinetic performances of digits when holding a pen. This study thus attempts to investigate pen-grip kinetics during writing tasks of school-age children and explore the relationship between the kinetic factors and fine motor skills. This study recruited 181 children aged from 5 to 12 years old and investigated the effects of age on handwriting kinetics and the relationship between these and fine motor skills. The forces applied from the digits and pen-tip were measured during writing tasks via a force acquisition pen, and the children's fine motor performances were also evaluated. The results indicate that peak force and average force might not be direct indicators of handwriting performance for normally developing children at this age. Younger children showed larger force variation and lower adjustment frequency during writing, which might indicate they had poorer force control than the older children. Force control when handling a pen is significantly correlated with fine motor performance, especially in relation to the manual dexterity. A novel system is proposed for analysing school-age children's force control while handwriting. We observed the development of force control in relation to pen grip among the children with different ages in this study. The findings suggested that manipulation skill may be crucial when children are establishing their handwriting capabilities. © 2017 Occupational Therapy Australia.

  2. Special Forces Command and Control in Afghanistan

    National Research Council Canada - National Science Library

    Rhyne, Richard

    2004-01-01

    .... The author examines how Special Forces and conventional forces worked together in the past in Vietnam, Panama, Somalia, Haiti, Bosnia-Herzegovina, and Operations Desert Storm and Desert Shield...

  3. Visual feedback alters force control and functional activity in the visuomotor network after stroke

    Directory of Open Access Journals (Sweden)

    Derek B. Archer

    2018-01-01

    Full Text Available Modulating visual feedback may be a viable option to improve motor function after stroke, but the neurophysiological basis for this improvement is not clear. Visual gain can be manipulated by increasing or decreasing the spatial amplitude of an error signal. Here, we combined a unilateral visually guided grip force task with functional MRI to understand how changes in the gain of visual feedback alter brain activity in the chronic phase after stroke. Analyses focused on brain activation when force was produced by the most impaired hand of the stroke group as compared to the non-dominant hand of the control group. Our experiment produced three novel results. First, gain-related improvements in force control were associated with an increase in activity in many regions within the visuomotor network in both the stroke and control groups. These regions include the extrastriate visual cortex, inferior parietal lobule, ventral premotor cortex, cerebellum, and supplementary motor area. Second, the stroke group showed gain-related increases in activity in additional regions of lobules VI and VIIb of the ipsilateral cerebellum. Third, relative to the control group, the stroke group showed increased activity in the ipsilateral primary motor cortex, and activity in this region did not vary as a function of visual feedback gain. The visuomotor network, cerebellum, and ipsilateral primary motor cortex have each been targeted in rehabilitation interventions after stroke. Our observations provide new insight into the role these regions play in processing visual gain during a precisely controlled visuomotor task in the chronic phase after stroke.

  4. Exoskeleton master controller with force-reflecting telepresence

    Science.gov (United States)

    Burke, James B.; Bartholet, Stephen J.; Nelson, David K.

    1992-01-01

    A thorough understanding of the requirements for successful master-slave robotic systems is becoming increasingly desirable. Such systems can aid in the accomplishment of tasks that are hazardous or inaccessible to humans. Although a history of use has proven master-slave systems to be viable, system requirements and the impact of specifications on the human factors side of system performance are not well known. In support of the next phase of teleoperation research being conducted at the Armstrong Research Laboratory, a force-reflecting, seven degree of freedom exoskeleton for master-slave teleoperation has been concepted, and is presently being developed. The exoskeleton has a unique kinematic structure that complements the structure of the human arm. It provides a natural means for teleoperating a dexterous, possibly redundant manipulator. It allows ease of use without operator fatigue and faithfully follows human arm and wrist motions. Reflected forces and moments are remotely transmitted to the operator hand grip using a cable transmission scheme. This paper presents the exoskeleton concept and development results to date. Conceptual design, hardware, algorithms, computer architecture, and software are covered.

  5. Gemstone Grinding Process Improvement by using Impedance Force Control

    Directory of Open Access Journals (Sweden)

    Hamprommarat Chumpol

    2015-01-01

    Full Text Available Chula Automatic Faceting Machine has been developed by The Advance Manufacturing Research Lab, Chulalongkorn University to support Thailand Gems-Industry. The machine has high precision motion control by using position and force control. A contact stiffness model is used to estimate grinding force. Although polished gems from the Faceting Machine have uniform size and acceptable shape, the force of the grinding and polishing process cannot be maintain constant and has some fluctuation due to indirect force control. Therefor this research work propose a new controller for this process based on an impedance direct force control to improve the gemstone grinding performance during polishing process. The grinding force can be measured through motor current. The results show that the polished gems by using impedance direct force control can maintain uniform size as well as good shape and high quality surface.

  6. Surface EMG and intra-socket force measurement to control a prosthetic device

    Science.gov (United States)

    Sanford, Joe; Patterson, Rita; Popa, Dan

    2015-06-01

    Surface electromyography (SEMG) has been shown to be a robust and reliable interaction method allowing for basic control of powered prosthetic devices. Research has shown a marked decrease in EMG-classification efficiency throughout activities of daily life due to socket shift and movement and fatigue as well as changes in degree of fit of the socket throughout the subject's lifetime. Users with the most severe levels of amputation require the most complex devices with the greatest number of degrees of freedom. Controlling complex dexterous devices with limited available inputs requires the addition of sensing and interaction modalities. However, the larger the amputation severity, the fewer viable SEMG sites are available as control inputs. Previous work reported the use of intra-socket pressure, as measured during wrist flexion and extension, and has shown that it is possible to control a powered prosthetic device with pressure sensors. In this paper, we present data correlations of SEMG data with intra-socket pressure data. Surface EMG sensors and force sensors were housed within a simulated prosthetic cuff fit to a healthy-limbed subject. EMG and intra-socket force data was collected from inside the cuff as a subject performed pre-defined grip motions with their dominant hand. Data fusion algorithms were explored and allowed a subject to use both intra-socket pressure and SEMG data as control inputs for a powered prosthetic device. This additional input modality allows for an improvement in input classification as well as information regarding socket fit through out activities of daily life.

  7. Force-sensed interface for control and training space robot

    Science.gov (United States)

    Moiseev, O. S.; Sarsadskikh, A. S.; Povalyaev, N. D.; Gorbunov, V. I.; Kulakov, F. M.; Vasilev, V. V.

    2018-05-01

    A method of positional and force-torque control of robots is proposed. Prototypes of the system and the master handle have been created. Algorithm of bias estimation and gravity compensation for force-torque sensor and force-torque trajectory correction are described.

  8. Force Reflection Algorithms for Exoskeleton Controllers

    National Research Council Canada - National Science Library

    Bryfogle, Mark

    1991-01-01

    This research effort investigated the kinematics and dynamics of open chain, serial linkage mechanisms with specific emphasis placed upon the application of this linkage as a force reflecting exoskeleton mechanism...

  9. Computer-Controlled Force Generator, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — TDA Research, Inc. is developing a compact, low power, Next-Generation Exercise Device (NGRED) that can generate any force between 5 and 600 lbf. We use a closed...

  10. High Cable Forces Deteriorate Pinch Force Control in Voluntary-Closing Body-Powered Prostheses.

    Directory of Open Access Journals (Sweden)

    Mona Hichert

    Full Text Available It is generally asserted that reliable and intuitive control of upper-limb prostheses requires adequate feedback of prosthetic finger positions and pinch forces applied to objects. Body-powered prostheses (BPPs provide the user with direct proprioceptive feedback. Currently available BPPs often require high cable operation forces, which complicates control of the forces at the terminal device. The aim of this study is to quantify the influence of high cable forces on object manipulation with voluntary-closing prostheses.Able-bodied male subjects were fitted with a bypass-prosthesis with low and high cable force settings for the prehensor. Subjects were requested to grasp and transfer a collapsible object as fast as they could without dropping or breaking it. The object had a low and a high breaking force setting.Subjects conducted significantly more successful manipulations with the low cable force setting, both for the low (33% more and high (50% object's breaking force. The time to complete the task was not different between settings during successful manipulation trials.High cable forces lead to reduced pinch force control during object manipulation. This implies that low cable operation forces should be a key design requirement for voluntary-closing BPPs.

  11. Force Control Strategies in Hydraulically Actuated Legged Robots

    Directory of Open Access Journals (Sweden)

    Hector Montes

    2016-03-01

    Full Text Available In this contribution, several strategies of force control have been proposed to be implemented and evaluated in ROBOCLIMBER, a quadruped robot of large dimensions. A first group of strategies proposed in this paper is based on impedance control, which is intended to adapt the foot-ground contact forces according to the experimentally specified damping ratio and the undamped natural frequency. A second control strategy of interest for many practical cases is called the parallel force/position control, which has one inner loop position control and two external control loops, one of force and another of position. A third group of control strategies is the posture stabilization for ROBOCLIMBER using the feedback of the ZMP calculation and the position of its legs. Finally, a control strategy for the control of a quasi-static gait using ZMP feedback is proposed and tested by simulation.

  12. The effects of grip width on sticking region in bench press.

    Science.gov (United States)

    Gomo, Olav; Van Den Tillaar, Roland

    2016-01-01

    The aim of this study was to examine the occurrence of the sticking region by examining how three different grip widths affect the sticking region in powerlifters' bench press performance. It was hypothesised that the sticking region would occur at the same joint angle of the elbow and shoulder independent of grip width, indicating a poor mechanical region for vertical force production at these joint angles. Twelve male experienced powerlifters (age 27.7 ± 8.8 years, mass 91.9 ± 15.4 kg) were tested in one repetition maximum (1-RM) bench press with a narrow, medium and wide grip. Joint kinematics, timing, bar position and velocity were measured with a 3D motion capture system. All participants showed a clear sticking region with all three grip widths, but this sticking region was not found to occur at the same joint angles in all three grip widths, thereby rejecting the hypothesis that the sticking region would occur at the same joint angle of the elbow and shoulder independent of grip width. It is suggested that, due to the differences in moment arm of the barbell about the elbow joint in the sticking region, there still might be a poor mechanical region for total force production that is joint angle-specific.

  13. Neural control of muscle force: indications from a simulation model

    Science.gov (United States)

    Luca, Carlo J. De

    2013-01-01

    We developed a model to investigate the influence of the muscle force twitch on the simulated firing behavior of motoneurons and muscle force production during voluntary isometric contractions. The input consists of an excitatory signal common to all the motor units in the pool of a muscle, consistent with the “common drive” property. Motor units respond with a hierarchically structured firing behavior wherein at any time and force, firing rates are inversely proportional to recruitment threshold, as described by the “onion skin” property. Time- and force-dependent changes in muscle force production are introduced by varying the motor unit force twitches as a function of time or by varying the number of active motor units. A force feedback adjusts the input excitation, maintaining the simulated force at a target level. The simulations replicate motor unit behavior characteristics similar to those reported in previous empirical studies of sustained contractions: 1) the initial decrease and subsequent increase of firing rates, 2) the derecruitment and recruitment of motor units throughout sustained contractions, and 3) the continual increase in the force fluctuation caused by the progressive recruitment of larger motor units. The model cautions the use of motor unit behavior at recruitment and derecruitment without consideration of changes in the muscle force generation capacity. It describes an alternative mechanism for the reserve capacity of motor units to generate extraordinary force. It supports the hypothesis that the control of motoneurons remains invariant during force-varying and sustained isometric contractions. PMID:23236008

  14. Precision Force Control for an Electro-Hydraulic Press Machine

    Directory of Open Access Journals (Sweden)

    Hong-Ming Chen

    2014-08-01

    Full Text Available This thesis is primarily intended to design a PC-based control system to control the force of an electro-hydraulic servo press system for implementing precision force control. The main feature is to develop a composite control by using the relief valve and the flow servo valve. Using feedback from a force sensor, a fuzzy controller was designed with LabVIEW software as the system control core for achieving a precision force control for the hydraulic cylinder on its travel and output. The weakness of hydraulic systems is that hydraulic oil is compressible and prone to leaking, and its characteristics can vary with oil temperature, thus making it difficult for a general linear controller to achieve accurate control. Therefore, a fuzzy controller was designed with LabVIEW along with a NI-PCI_6221 interface card and a load cell to control the servo valve flow and the relief valve to control the pressure source. The testing results indicate that accurate force control output of an electro-hydraulic servo press system can be obtained.

  15. A novel adaptive force control method for IPMC manipulation

    International Nuclear Information System (INIS)

    Hao, Lina; Sun, Zhiyong; Su, Yunquan; Gao, Jianchao; Li, Zhi

    2012-01-01

    IPMC is a type of electro-active polymer material, also called artificial muscle, which can generate a relatively large deformation under a relatively low input voltage (generally speaking, less than 5 V), and can be implemented in a water environment. Due to these advantages, IPMC can be used in many fields such as biomimetics, service robots, bio-manipulation, etc. Until now, most existing methods for IPMC manipulation are displacement control not directly force control, however, under most conditions, the success rate of manipulations for tiny fragile objects is limited by the contact force, such as using an IPMC gripper to fix cells. Like most EAPs, a creep phenomenon exists in IPMC, of which the generated force will change with time and the creep model will be influenced by the change of the water content or other environmental factors, so a proper force control method is urgently needed. This paper presents a novel adaptive force control method (AIPOF control—adaptive integral periodic output feedback control), based on employing a creep model of which parameters are obtained by using the FRLS on-line identification method. The AIPOF control method can achieve an arbitrary pole configuration as long as the plant is controllable and observable. This paper also designs the POF and IPOF controller to compare their test results. Simulation and experiments of micro-force-tracking tests are carried out, with results confirming that the proposed control method is viable. (paper)

  16. Anticipatory synergy adjustments reflect individual performance of feedforward force control.

    Science.gov (United States)

    Togo, Shunta; Imamizu, Hiroshi

    2016-10-06

    We grasp and dexterously manipulate an object through multi-digit synergy. In the framework of the uncontrolled manifold (UCM) hypothesis, multi-digit synergy is defined as the coordinated control mechanism of fingers to stabilize variable important for task success, e.g., total force. Previous studies reported anticipatory synergy adjustments (ASAs) that correspond to a drop of the synergy index before a quick change of the total force. The present study compared ASA's properties with individual performances of feedforward force control to investigate a relationship of those. Subjects performed a total finger force production task that consisted of a phase in which subjects tracked target line with visual information and a phase in which subjects produced total force pulse without visual information. We quantified their multi-digit synergy through UCM analysis and observed significant ASAs before producing total force pulse. The time of the ASA initiation and the magnitude of the drop of the synergy index were significantly correlated with the error of force pulse, but not with the tracking error. Almost all subjects showed a significant increase of the variance that affected the total force. Our study directly showed that ASA reflects the individual performance of feedforward force control independently of target-tracking performance and suggests that the multi-digit synergy was weakened to adjust the multi-digit movements based on a prediction error so as to reduce the future error. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  17. Force-directed design of a voluntary closing hand prosthesis

    NARCIS (Netherlands)

    De Visser, H.; Herder, J.L.

    2000-01-01

    This paper presents the design of a body-powered voluntary closing prosthetic hand. It is argued that the movement of the fingers before establishing a grip is much less relevant for good control of the object held than the distribution of forces once the object has been contacted. Based on this

  18. Research on Grinding and Polishing Force Control of Compliant Flange

    Directory of Open Access Journals (Sweden)

    Li Chuang

    2015-01-01

    Full Text Available The automation of the grinding and polishing process is important to improve the production efficiency of the part surfaces. In this paper, a new compliant flange mounted on the end of the industrial robots for the robotic grinding and polishing force control is developed. With regard to the non-linear and time-varying problem of the contact force, the mathematical model of the new force control system was presented and the fuzzy PID control strategy was used to drive the proposed system. Especially, the air spring and electric proportional valve is studied to establish the model. The simulation results show that the selected control strategy has quick response and good robustness, which satisfies the real-time requirements of the grinding and polishing force control in processing.

  19. Force characteristics in continuous path controlled crankpin grinding

    Science.gov (United States)

    Zhang, Manchao; Yao, Zhenqiang

    2015-03-01

    Recent research on the grinding force involved in cylindrical plunge grinding has focused mainly on steady-state conditions. Unlike in conventional external cylindrical plunge grinding, the conditions between the grinding wheel and the crankpin change periodically in path controlled grinding because of the eccentricity of the crankpin and the constant rotational speed of the crankshaft. The objective of this study is to investigate the effects of various grinding conditions on the characteristics of the grinding force during continuous path controlled grinding. Path controlled plunge grinding is conducted at a constant rotational speed using a cubic boron nitride (CBN) wheel. The grinding force is determined by measuring the torque. The experimental results show that the force and torque vary sinusoidally during dry grinding and load grinding. The variations in the results reveal that the resultant grinding force and torque decrease with higher grinding speeds and increase with higher peripheral speeds of the pin and higher grinding depths. In path controlled grinding, unlike in conventional external cylindrical plunge grinding, the axial grinding force cannot be disregarded. The speeds and speed ratios of the workpiece and wheel are also analyzed, and the analysis results show that up-grinding and down-grinding occur during the grinding process. This paper proposes a method for describing the force behavior under varied process conditions during continuous path controlled grinding, which provides a beneficial reference for describing the material removal mechanism and for optimizing continuous controlled crankpin grinding.

  20. Control of force during rapid visuomotor force-matching tasks can be described by discrete time PID control algorithms.

    Science.gov (United States)

    Dideriksen, Jakob Lund; Feeney, Daniel F; Almuklass, Awad M; Enoka, Roger M

    2017-08-01

    Force trajectories during isometric force-matching tasks involving isometric contractions vary substantially across individuals. In this study, we investigated if this variability can be explained by discrete time proportional, integral, derivative (PID) control algorithms with varying model parameters. To this end, we analyzed the pinch force trajectories of 24 subjects performing two rapid force-matching tasks with visual feedback. Both tasks involved isometric contractions to a target force of 10% maximal voluntary contraction. One task involved a single action (pinch) and the other required a double action (concurrent pinch and wrist extension). 50,000 force trajectories were simulated with a computational neuromuscular model whose input was determined by a PID controller with different PID gains and frequencies at which the controller adjusted muscle commands. The goal was to find the best match between each experimental force trajectory and all simulated trajectories. It was possible to identify one realization of the PID controller that matched the experimental force produced during each task for most subjects (average index of similarity: 0.87 ± 0.12; 1 = perfect similarity). The similarities for both tasks were significantly greater than that would be expected by chance (single action: p = 0.01; double action: p = 0.04). Furthermore, the identified control frequencies in the simulated PID controller with the greatest similarities decreased as task difficulty increased (single action: 4.0 ± 1.8 Hz; double action: 3.1 ± 1.3 Hz). Overall, the results indicate that discrete time PID controllers are realistic models for the neural control of force in rapid force-matching tasks involving isometric contractions.

  1. Remodeling Air Force Cyber Command and Control

    Science.gov (United States)

    2017-10-10

    Internet, telecommunications networks, computer systems , and embedded processors and controllers .” That last phrase includes processors and controllers ...embedded” into weapons systems , including aircraft and spacecraft. Many weapon systems were built and connected before cyberspace became a...problems for systemic improvement of mission assurance. The benefit of a centralized environment could also extend to improving enterprise-level patch

  2. The handyman's brain: a neuroimaging meta-analysis describing the similarities and differences between grip type and pattern in humans.

    Science.gov (United States)

    King, M; Rauch, H G; Stein, D J; Brooks, S J

    2014-11-15

    Handgrip is a ubiquitous human movement that was critical in our evolution. However, the differences in brain activity between grip type (i.e. power or precision) and pattern (i.e. dynamic or static) are not fully understood. In order to address this, we performed Activation Likelihood Estimation (ALE) analysis between grip type and grip pattern using functional magnetic resonance imaging (fMRI) data. ALE provides a probabilistic summary of the BOLD response in hundreds of subjects, which is often beyond the scope of a single fMRI experiment. We collected data from 28 functional magnetic resonance data sets, which included a total of 398 male and female subjects. Using ALE, we analyzed the BOLD response during power, precision, static and dynamic grip in a range of forces and age in right handed healthy individuals without physical impairment, cardiovascular or neurological dysfunction using a variety of grip tools, feedback and experimental training. Power grip generates unique activation in the postcentral gyrus (areas 1 and 3b) and precision grip generates unique activation in the supplementary motor area (SMA, area 6) and precentral gyrus (area 4a). Dynamic handgrip generates unique activation in the precentral gyrus (area 4p) and SMA (area 6) and of particular interest, both dynamic and static grip share activation in the area 2 of the postcentral gyrus, an area implicated in the evolution of handgrip. According to effect size analysis, precision and dynamic grip generates stronger activity than power and static, respectively. Our study demonstrates specific differences between grip type and pattern. However, there was a large degree of overlap in the pre and postcentral gyrus, SMA and areas of the frontal-parietal-cerebellar network, which indicates that other mechanisms are potentially involved in regulating handgrip. Further, our study provides empirically based regions of interest, which can be downloaded here within, that can be used to more effectively

  3. Controlling Force and Depth in Friction Stir Welding

    Science.gov (United States)

    Adams, Glynn; Loftus, Zachary; McCormac, Nathan; Venable, Richard

    2005-01-01

    Feedback control of the penetration force applied to a pin tool in friction stir welding has been found to be a robust and reliable means for controlling the depth of penetration of the tool. This discovery has made it possible to simplify depth control and to weld with greater repeatability, even on workpieces with long weld joints. Prior to this discovery, depths of penetration in friction stir welding were controlled by hard-tooled roller assemblies or by depth actuators controlled by feedback from such external sensors as linear variable-differential transformers or laser-based devices. These means of control are limited: A hard-tooled roller assembly confines a pin tool to a preset depth that cannot be changed easily during the welding process. A measurement by an external sensor is only an indirect indicative of the depth of penetration, and computations to correlate such a measurement with a depth of penetration are vulnerable to error. The present force-feedback approach exploits the proportionality between the depth and the force of penetration Unlike a depth measurement taken by an external sensor, a force measurement can be direct because it can be taken by a sensor coupled directly to the pin tool. The reading can be processed through a modern electronic servo control system to control an actuator to keep the applied penetration force at the desired level. In comparison with the older depth-control methods described above, this method offers greater sensitivity to plasticizing of the workpiece metal and is less sensitive to process noise, resulting in a more consistent process. In an experiment, a tapered panel was friction stir welded while controlling the force of penetration according to this method. The figure is a plot of measurements taken during the experiment, showing that force was controlled with a variation of 200 lb (890 N), resulting in control of the depth of penetration with a variation of 0.004 in. (0.1 mm).

  4. GRIP HURRICANE IMAGING RADIOMETER (HIRAD) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Hurricane Imaging Radiometer (HIRAD) V1 dataset contains measurements of brightness temperature taken at 4, 5, 6 and 6.6 GHz, as well as MERRA 2 m wind...

  5. GRIP LIGHTNING INSTRUMENT PACKAGE (LIP) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Lightning Instrument Package (LIP) dataset was collected by the Lightning Instrument Package (LIP), which consists of 6 rotating vane type electric field...

  6. GRIP FLIGHT TRACKS AND ANIMATIONS V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Flight Tracks and Animations dataset includes both KML files and animation files. The KML files use Google Earth to show the flight tracks on a map. The...

  7. Performance evaluation on force control for ITER blanket installation

    Energy Technology Data Exchange (ETDEWEB)

    Aburadani, A., E-mail: aburadani.atsushi@jaea.go.jp [Japan Atomic Energy Agency, Mukouyama 801-1, Naka, Ibaraki 311-0193 (Japan); Takeda, N.; Shigematsu, S.; Murakami, S.; Tanigawa, H.; Kakudate, S. [Japan Atomic Energy Agency, Mukouyama 801-1, Naka, Ibaraki 311-0193 (Japan); Nakahira, M.; Hamilton, D.; Tesini, A. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

    2013-10-15

    Highlights: ► It is crucial issues to avoid any jamming between the blanket modules and the keys. ► Force control for AC servo motor was developed to reduce excessive loads. ► This jam prevention force control method is directly measured and controlled by AC servo motor controllers. ► In the recent test, the module was passively positioned onto keys using the torque control method. -- Abstract: The most critical issue for the ITER blanket installation is to avoid any jamming between the blanket modules and the keys as a result of excessive loading during the module installation process. This is complicated by the limited clearance of 0.5 mm between the modules and the keys. To solve these technical issues, force control, such as controlling the torque for the AC servo motors, was developed to reduce excessive loads which may have an impact on the end-effector and to defer the forces acting on the groove of the blanket. This jam prevention force control method is directly measured and controlled by AC servo motor controllers. The AC servo motors are equipped to move the manipulator and end-effector during module installation.

  8. Performance evaluation on force control for ITER blanket installation

    International Nuclear Information System (INIS)

    Aburadani, A.; Takeda, N.; Shigematsu, S.; Murakami, S.; Tanigawa, H.; Kakudate, S.; Nakahira, M.; Hamilton, D.; Tesini, A.

    2013-01-01

    Highlights: ► It is crucial issues to avoid any jamming between the blanket modules and the keys. ► Force control for AC servo motor was developed to reduce excessive loads. ► This jam prevention force control method is directly measured and controlled by AC servo motor controllers. ► In the recent test, the module was passively positioned onto keys using the torque control method. -- Abstract: The most critical issue for the ITER blanket installation is to avoid any jamming between the blanket modules and the keys as a result of excessive loading during the module installation process. This is complicated by the limited clearance of 0.5 mm between the modules and the keys. To solve these technical issues, force control, such as controlling the torque for the AC servo motors, was developed to reduce excessive loads which may have an impact on the end-effector and to defer the forces acting on the groove of the blanket. This jam prevention force control method is directly measured and controlled by AC servo motor controllers. The AC servo motors are equipped to move the manipulator and end-effector during module installation

  9. Force analysis of magnetic bearings with power-saving controls

    International Nuclear Information System (INIS)

    Johnson, D.; Brown, G.V.; Inman, D.J.

    1992-01-01

    Most magnetic bearing control schemes use a bias current with a superimposed control current to linearize the relationship between the control current and the force it delivers. For most operating conditions, the existence of the bias current requires more power than alternative methods that do not use conventional bias. Two such methods are examined which diminish or eliminate bias current. In the typical bias control scheme it is found that for a harmonic control force command into a voltage limited transconductance amplifier, the desired force output is obtained only up to certain combinations of force amplitude and frequency. Above these values, the force amplitude is reduced and a phase lag occurs. The power saving alternative control schemes typically exhibit such deficiencies at even lower command frequencies and amplitudes. To assess the severity of these effects, a time history analysis of the force output is performed for the bias method and the alternative methods. Results of the analysis show that the alternative approaches may be viable. The various control methods examined were mathematically modeled using nondimensionalized variables to facilitate comparison of the various methods

  10. The Air Force Center for Optimal Design and Control

    National Research Council Canada - National Science Library

    Burns, John

    1997-01-01

    This report contains a summary and highlights of the research funded by the Air Force under AFOSR URI Grant F49620-93-1-0280, titled 'Center for Optimal Design and Control of Distributed Parameter Systems' (CODAC...

  11. Force control for mechanoinduction of impedance variation in cellular organisms

    International Nuclear Information System (INIS)

    Nam, Joo Hoo; Chen, Peter C Y; Lu, Zhe; Luo, Hong; Lin, Wei; Ge, Ruowen

    2010-01-01

    Constantly exposed to various forms of mechanical forces inherent in their physical environment (such as gravity, stress induced by fluid flow or cell–cell interactions, etc), cellular organisms sense such forces and convert them into biochemical signals through the processes of mechanosensing and mechanotransduction that eventually lead to biological changes. The effect of external forces on the internal structures and activities in a cellular organism may manifest in changes its physical properties, such as impedance. Studying variation in the impedance of a cellular organism induced by the application of an external mechanical force represents a meaningful endeavor (from a biosystems perspective) in exploring the complex mechanosensing and mechanotransduction mechanisms that govern the behavior of a cellular organism under the influence of external mechanical stimuli. In this paper we describe the development of an explicit force-feedback control system for exerting an indentation force on a cellular organism while simultaneously measuring its impedance. To demonstrate the effectiveness of this force-control system, we have conducted experiments using zebrafish embryos as a test model of a cellular organism. We report experimental results demonstrating that the application of a properly controlled external force leads to a significant change in the impedance of a zebrafish embryo. These results offer support for a plausible explanation that activities of pore canals in the chorion are responsible for the observed change in impedance.

  12. Effects of hyperthyroidism on hand grip strength and function

    OpenAIRE

    Esra Erkol İnal, MD; Alparslan Bayram Çarlı, MD; Sultan Çanak, MD; Oğuzhan Aksu, MD; Banu Kale Köroğlu, MD; Serpil Savaş

    2015-01-01

    Hyperthyroidism is a pathologic condition in which the body is exposed to excessive amounts of circulating thyroid hormones. Skeletal muscle is one of the major target organs of thyroid hormones. We evaluated hand grip strength and function in patients with overt hyperthyroidism. Fifty-one patients newly diagnosed with hyperthyroidism and 44 healthy controls participated in this study. Age, height, weight, and dominant hand of all participants were recorded. The diagnosis of hyperthyroidism w...

  13. Hybrid viscous damper with filtered integral force feedback control

    DEFF Research Database (Denmark)

    Høgsberg, Jan; Brodersen, Mark L.

    2016-01-01

    In hybrid damper systems active control devices are usually introduced to enhance the performance of otherwise passive dampers. In the present paper a hybrid damper concept is comprised of a passive viscous damper placed in series with an active actuator and a force sensor. The actuator motion...... is controlled by a filtered integral force feedback strategy, where the main feature is the filter, which is designed to render a damper force that in a phase-plane representation operates in front of the corresponding damper velocity. It is demonstrated that in the specific parameter regime where the damper...

  14. Effects of hyperthyroidism on hand grip strength and function.

    Science.gov (United States)

    Erkol İnal, Esra; Çarlı, Alparslan Bayram; Çanak, Sultan; Aksu, Oğuzhan; Köroğlu, Banu Kale; Savaş, Serpil

    2015-01-01

    Hyperthyroidism is a pathologic condition in which the body is exposed to excessive amounts of circulating thyroid hormones. Skeletal muscle is one of the major target organs of thyroid hormones. We evaluated hand grip strength and function in patients with overt hyperthyroidism. Fifty-one patients newly diagnosed with hyperthyroidism and 44 healthy controls participated in this study. Age, height, weight, and dominant hand of all participants were recorded. The diagnosis of hyperthyroidism was confirmed by clinical examination and laboratory tests. Hand grip strength was tested at the dominant hand with a Jamar hand dynamometer. The grooved pegboard test (PGT) was used to evaluate hand dexterity. The Duruöz Hand Index (DHI) was used to assess hand function. No significant differences were found in terms of clinical and demographic findings between the patients with hyperthyroidism and healthy controls (p > 0.05). Significant differences were found between the patients with hyperthyroidism and healthy controls regarding PGT and DHI scores (p Hyperthyroidism seemed to affect hand dexterity and function more than hand grip strength and seemed to be associated with reduced physical function more than muscle strength. This may also indicate that patients with hyperthyroidism should be evaluated by multidisplinary modalities.

  15. Theoretical analysis of steady state operating forces in control valves

    Directory of Open Access Journals (Sweden)

    Basavaraj Hubballi

    2018-01-01

    Full Text Available The controlling components, such as valves are used to regulate controlled fluid power. It is not always possible to calculate valve forces accurately, and with some types of valves even the existence of certain types of forces cannot be predicted with certainty. In many cases, however, the analysis can be made fairly completely and accurately. The assumption of steady state conditions is valid for the valve alone, but transient effects in the rest of the system may be large. These effects are particularly important with regard to the instability of valves, where the system may react on the valve in such a way as to make it squeal or oscillate, sometimes with large amplitude. The origin of the steady state flow force understood from a brief qualitative explanation. The following paper will summarize much of what is known about valve forces in the spool type controlling element.

  16. Environmental forcing, invasion and control of ecological and epidemiological systems.

    Science.gov (United States)

    Greenman, J V; Norman, R A

    2007-08-07

    Destabilising a biological system through periodic or stochastic forcing can lead to significant changes in system behaviour. Forcing can bring about coexistence when previously there was exclusion; it can excite massive system response through resonance, it can offset the negative effect of apparent competition and it can change the conditions under which the system can be invaded. Our main focus is on the invasion properties of continuous time models under periodic forcing. We show that invasion is highly sensitive to the strength, period, phase, shape and configuration of the forcing components. This complexity can be of great advantage if some of the forcing components are anthropogenic in origin. They can be turned into instruments of control to achieve specific objectives in ecology and disease management, for example. Culling, vaccination and resource regulation are considered. A general analysis is presented, based on the leading Lyapunov exponent criterion for invasion. For unstructured invaders, a formula for this exponent can typically be written down from the model equations. Whether forcing hinders or encourages invasion depends on two factors: the covariances between invader parameters and resident populations and the shifts in average resident population levels brought about by the forcing. The invasion dynamics of a structured invader are much more complicated but an analytic solution can be obtained in quadratic approximation for moderate forcing strength. The general theory is illustrated by a range of models drawn from ecology and epidemiology. The relationship between periodic and stochastic forcing is also considered.

  17. Force Feedback Control Method of Active Tuned Mass Damper

    Directory of Open Access Journals (Sweden)

    Xiuli Wang

    2017-01-01

    Full Text Available Active tuned mass dampers as vibration-control devices are widely used in many fields for their good stability and effectiveness. To improve the performance of such dampers, a control method based on force feedback is proposed. The method offers several advantages such as high-precision control and low-performance requirements for the actuator, as well as not needing additional compensators. The force feedback control strategy was designed based on direct-velocity feedback. The effectiveness of the method was verified in a single-degree-of-freedom system, and factors such as damping effect, required active force, actuator stroke, and power consumption of the damper were analyzed. Finally, a simulation study was performed by configuring a main complex elastic-vibration-damping system. The results show that the method provides effective control over modal resonances of multiple orders of the system and improves its dynamics performance.

  18. Controlling the Casimir force via the electromagnetic properties of materials

    International Nuclear Information System (INIS)

    Yang Yaping; Chen Hong; Zeng Ran; Zhu Shiyao; Zubairy, M. Suhail

    2010-01-01

    The control of the Casimir force between two parallel plates can be achieved through adjusting the frequency-dependent electromagnetic properties of materials of the two plates. We show that, for different plate separations, the main contribution to the Casimir force comes from different frequency regions: For smaller (larger) separation, it comes from the higher (lower) frequency region. When the separation of the plates increases, the Casimir force can vary from attractive to repulsive and/or vice versa, by selecting the two plates with suitable electromagnetic properties. We discuss how a restoring Casimir force, which varies from repulsive to attractive by increasing the separation, can be realized and that the stable equilibrium is formed at zero Casimir force.

  19. Coherence and interlimb force control: Effects of visual gain.

    Science.gov (United States)

    Kang, Nyeonju; Cauraugh, James H

    2018-03-06

    Neural coupling across hemispheres and homologous muscles often appears during bimanual motor control. Force coupling in a specific frequency domain may indicate specific bimanual force coordination patterns. This study investigated coherence on pairs of bimanual isometric index finger force while manipulating visual gain and task asymmetry conditions. We used two visual gain conditions (low and high gain = 8 and 512 pixels/N), and created task asymmetry by manipulating coefficient ratios imposed on the left and right index finger forces (0.4:1.6; 1:1; 1.6:0.4, respectively). Unequal coefficient ratios required different contributions from each hand to the bimanual force task resulting in force asymmetry. Fourteen healthy young adults performed bimanual isometric force control at 20% of their maximal level of the summed force of both fingers. We quantified peak coherence and relative phase angle between hands at 0-4, 4-8, and 8-12 Hz, and estimated a signal-to-noise ratio of bimanual forces. The findings revealed higher peak coherence and relative phase angle at 0-4 Hz than at 4-8 and 8-12 Hz for both visual gain conditions. Further, peak coherence and relative phase angle values at 0-4 Hz were larger at the high gain than at the low gain. At the high gain, higher peak coherence at 0-4 Hz collapsed across task asymmetry conditions significantly predicted greater signal-to-noise ratio. These findings indicate that a greater level of visual information facilitates bimanual force coupling at a specific frequency range related to sensorimotor processing. Copyright © 2018 Elsevier B.V. All rights reserved.

  20. External force/velocity control for an autonomous rehabilitation robot

    Science.gov (United States)

    Saekow, Peerayuth; Neranon, Paramin; Smithmaitrie, Pruittikorn

    2018-01-01

    Stroke is a primary cause of death and the leading cause of permanent disability in adults. There are many stroke survivors, who live with a variety of levels of disability and always need rehabilitation activities on daily basis. Several studies have reported that usage of rehabilitation robotic devices shows the better improvement outcomes in upper-limb stroke patients than the conventional therapy-nurses or therapists actively help patients with exercise-based rehabilitation. This research focuses on the development of an autonomous robotic trainer designed to guide a stroke patient through an upper-limb rehabilitation task. The robotic device was designed and developed to automate the reaching exercise as mentioned. The designed robotic system is made up of a four-wheel omni-directional mobile robot, an ATI Gamma multi-axis force/torque sensor used to measure contact force and a microcontroller real-time operating system. Proportional plus Integral control was adapted to control the overall performance and stability of the autonomous assistive robot. External force control was successfully implemented to establish the behavioral control strategy for the robot force and velocity control scheme. In summary, the experimental results indicated satisfactorily stable performance of the robot force and velocity control can be considered acceptable. The gain tuning for proportional integral (PI) velocity control algorithms was suitably estimated using the Ziegler-Nichols method in which the optimized proportional and integral gains are 0.45 and 0.11, respectively. Additionally, the PI external force control gains were experimentally tuned using the trial and error method based on a set of experiments which allow a human participant moves the robot along the constrained circular path whilst attempting to minimize the radial force. The performance was analyzed based on the root mean square error (E_RMS) of the radial forces, in which the lower the variation in radial

  1. Control of weakly conductive fluids by near wall Lorentz forces

    Energy Technology Data Exchange (ETDEWEB)

    Hinze, M. [Technische Univ. Dresden (Germany). Inst. fuer Numerische Mathematik

    2007-07-01

    In this work optimal and model-predictive control approaches for control of weakly conductive fluids are developed. The flow around the circular cylinder at low Reynolds numbers serves as prototyping application. Control by near-wall Lorentz forces gains either to suppress the formation of the von Karman Vortex Street, or to reduce the drag. Besides a concise mathematical modelling numerical examples are presented which highlight the scope of the presented control approaches. (orig.)

  2. Report of the Material Control and Material Accounting Task Force

    International Nuclear Information System (INIS)

    1978-03-01

    In September 1977 a Task Force was formed to complete a study of the role of material control and material accounting in NRC's safeguards program. The Task Force's assignment was to: define the roles and objectives of material control and material accounting in the NRC safeguards program; recommend goals for the material control and material accounting systems based on their roles and objectives; assess the extent to which the existing safeguards regulatory base meets or provides the capability to meet the recommended goals; and provide direction for material control and material accounting development, including both near-term and long-term upgrades. The study was limited to domestic nuclear facilities possessing significant amounts of plutonium, uranium-233 or highly enriched uranium in unsealed form. The Task Force findings are reported

  3. Myoelectric hand prosthesis force control through servo motor current feedback.

    Science.gov (United States)

    Sono, Tálita Saemi Payossim; Menegaldo, Luciano Luporini

    2009-10-01

    This paper presents the prehension force closed-loop control design of a mechanical finger commanded by electromyographic signal (EMG) from a patient's arm. The control scheme was implemented and tested in a mechanical finger prototype with three degrees of freedom and one actuator, driven by arm muscles EMG of normal volunteers. Real-time indirect estimation of prehension force was assessed by measuring the DC servo motor actuator current. A model of the plant comprising finger, motor, and grasped object was proposed. Model parameters were identified experimentally and a classical feedback phase-lead compensator was designed. The controlled mechanical finger was able to provide a more accurate prehension force modulation of a compliant object when compared to open-loop control.

  4. Optimal integral force feedback for active vibration control

    Science.gov (United States)

    Teo, Yik R.; Fleming, Andrew J.

    2015-11-01

    This paper proposes an improvement to Integral Force Feedback (IFF), which is a popular method for active vibration control of structures and mechanical systems. Benefits of IFF include robustness, guaranteed stability and simplicity. However, the maximum damping performance is dependent on the stiffness of the system; hence, some systems cannot be adequately controlled. In this paper, an improvement to the classical force feedback control scheme is proposed. The improved method achieves arbitrary damping for any mechanical system by introducing a feed-through term. The proposed improvement is experimentally demonstrated by actively damping an objective lens assembly for a high-speed confocal microscope.

  5. Electrotactile EMG feedback improves the control of prosthesis grasping force

    Science.gov (United States)

    Schweisfurth, Meike A.; Markovic, Marko; Dosen, Strahinja; Teich, Florian; Graimann, Bernhard; Farina, Dario

    2016-10-01

    Objective. A drawback of active prostheses is that they detach the subject from the produced forces, thereby preventing direct mechanical feedback. This can be compensated by providing somatosensory feedback to the user through mechanical or electrical stimulation, which in turn may improve the utility, sense of embodiment, and thereby increase the acceptance rate. Approach. In this study, we compared a novel approach to closing the loop, namely EMG feedback (emgFB), to classic force feedback (forceFB), using electrotactile interface in a realistic task setup. Eleven intact-bodied subjects and one transradial amputee performed a routine grasping task while receiving emgFB or forceFB. The two feedback types were delivered through the same electrotactile interface, using a mixed spatial/frequency coding to transmit 8 discrete levels of the feedback variable. In emgFB, the stimulation transmitted the amplitude of the processed myoelectric signal generated by the subject (prosthesis input), and in forceFB the generated grasping force (prosthesis output). The task comprised 150 trials of routine grasping at six forces, randomly presented in blocks of five trials (same force). Interquartile range and changes in the absolute error (AE) distribution (magnitude and dispersion) with respect to the target level were used to assess precision and overall performance, respectively. Main results. Relative to forceFB, emgFB significantly improved the precision of myoelectric commands (min/max of the significant levels) for 23%/36% as well as the precision of force control for 12%/32%, in intact-bodied subjects. Also, the magnitude and dispersion of the AE distribution were reduced. The results were similar in the amputee, showing considerable improvements. Significance. Using emgFB, the subjects therefore decreased the uncertainty of the forward pathway. Since there is a correspondence between the EMG and force, where the former anticipates the latter, the emgFB allowed for

  6. Effect of adding the novel fiber, PGX®, to commonly consumed foods on glycemic response, glycemic index and GRIP: a simple and effective strategy for reducing post prandial blood glucose levels - a randomized, controlled trial

    Directory of Open Access Journals (Sweden)

    Lyon Michael

    2010-11-01

    Full Text Available Abstract Background Reductions in postprandial glycemia have been demonstrated previously with the addition of the novel viscous polysaccharide (NVP, PolyGlycopleX® (PGX®, to an OGTT or white bread. This study explores whether these reductions are sustained when NVP is added to a range of commonly consumed foods or incorporated into a breakfast cereal. Methods Ten healthy subjects (4M, 6F; age 37.3 ± 3.6 y; BMI 23.8 ± 1.3 kg/m2, participated in an acute, randomized controlled trial. The glycemic response to cornflakes, rice, yogurt, and a frozen dinner with and without 5 g of NVP sprinkled onto the food was determined. In addition, 3 granolas with different levels of NVP and 3 control white breads and one white bread and milk were also consumed. All meals contained 50 g of available carbohydrate. Capillary blood samples were taken fasting and at 15, 30, 45, 60, 90 and 120 min after the start of the meal. The glycemic index (GI and the glycemic reduction index potential (GRIP were calculated. The blood glucose concentrations at each time and the iAUC values were subjected to repeated-measures analysis of variance (ANOVA examining for the effect of test meal. After demonstration of significant heterogeneity, differences between individual means was assessed using GLM ANOVA with Tukey test to adjust for multiple comparisons. Results Addition of NVP reduced blood glucose response irrespective of food or dose (p Conclusion Sprinkling or incorporation of NVP into a variety of different foods is highly effective in reducing postprandial glycemia and lowering the GI of a food. Clinical Trial registration NCT00935350.

  7. Accurate fluid force measurement based on control surface integration

    Science.gov (United States)

    Lentink, David

    2018-01-01

    Nonintrusive 3D fluid force measurements are still challenging to conduct accurately for freely moving animals, vehicles, and deforming objects. Two techniques, 3D particle image velocimetry (PIV) and a new technique, the aerodynamic force platform (AFP), address this. Both rely on the control volume integral for momentum; whereas PIV requires numerical integration of flow fields, the AFP performs the integration mechanically based on rigid walls that form the control surface. The accuracy of both PIV and AFP measurements based on the control surface integration is thought to hinge on determining the unsteady body force associated with the acceleration of the volume of displaced fluid. Here, I introduce a set of non-dimensional error ratios to show which fluid and body parameters make the error negligible. The unsteady body force is insignificant in all conditions where the average density of the body is much greater than the density of the fluid, e.g., in gas. Whenever a strongly deforming body experiences significant buoyancy and acceleration, the error is significant. Remarkably, this error can be entirely corrected for with an exact factor provided that the body has a sufficiently homogenous density or acceleration distribution, which is common in liquids. The correction factor for omitting the unsteady body force, {{{ {ρ f}} {1 - {ρ f} ( {{ρ b}+{ρ f}} )}.{( {{{{ρ }}b}+{ρ f}} )}}} , depends only on the fluid, {ρ f}, and body, {{ρ }}b, density. Whereas these straightforward solutions work even at the liquid-gas interface in a significant number of cases, they do not work for generalized bodies undergoing buoyancy in combination with appreciable body density inhomogeneity, volume change (PIV), or volume rate-of-change (PIV and AFP). In these less common cases, the 3D body shape needs to be measured and resolved in time and space to estimate the unsteady body force. The analysis shows that accounting for the unsteady body force is straightforward to non

  8. High cable forces deteriorate pinch force control in voluntary-closing body-powered prostheses

    NARCIS (Netherlands)

    Hichert, M.; Abbink, D.A.; Kyberd, P.J.; Plettenburg, D.H.

    2017-01-01

    Background It is generally asserted that reliable and intuitive control of upper-limb prostheses requires adequate feedback of prosthetic finger positions and pinch forces applied to objects. Bodypowered prostheses (BPPs) provide the user with direct proprioceptive feedback. Currently available

  9. Formation Control of Robotic Swarm Using Bounded Artificial Forces

    Science.gov (United States)

    Zha, Yabing; Peng, Yong

    2013-01-01

    Formation control of multirobot systems has drawn significant attention in the recent years. This paper presents a potential field control algorithm, navigating a swarm of robots into a predefined 2D shape while avoiding intermember collisions. The algorithm applies in both stationary and moving targets formation. We define the bounded artificial forces in the form of exponential functions, so that the behavior of the swarm drove by the forces can be adjusted via selecting proper control parameters. The theoretical analysis of the swarm behavior proves the stability and convergence properties of the algorithm. We further make certain modifications upon the forces to improve the robustness of the swarm behavior in the presence of realistic implementation considerations. The considerations include obstacle avoidance, local minima, and deformation of the shape. Finally, detailed simulation results validate the efficiency of the proposed algorithm, and the direction of possible futrue work is discussed in the conclusions. PMID:24453809

  10. Formation Control of Robotic Swarm Using Bounded Artificial Forces

    Directory of Open Access Journals (Sweden)

    Long Qin

    2013-01-01

    Full Text Available Formation control of multirobot systems has drawn significant attention in the recent years. This paper presents a potential field control algorithm, navigating a swarm of robots into a predefined 2D shape while avoiding intermember collisions. The algorithm applies in both stationary and moving targets formation. We define the bounded artificial forces in the form of exponential functions, so that the behavior of the swarm drove by the forces can be adjusted via selecting proper control parameters. The theoretical analysis of the swarm behavior proves the stability and convergence properties of the algorithm. We further make certain modifications upon the forces to improve the robustness of the swarm behavior in the presence of realistic implementation considerations. The considerations include obstacle avoidance, local minima, and deformation of the shape. Finally, detailed simulation results validate the efficiency of the proposed algorithm, and the direction of possible futrue work is discussed in the conclusions.

  11. Formation control of robotic swarm using bounded artificial forces.

    Science.gov (United States)

    Qin, Long; Zha, Yabing; Yin, Quanjun; Peng, Yong

    2013-01-01

    Formation control of multirobot systems has drawn significant attention in the recent years. This paper presents a potential field control algorithm, navigating a swarm of robots into a predefined 2D shape while avoiding intermember collisions. The algorithm applies in both stationary and moving targets formation. We define the bounded artificial forces in the form of exponential functions, so that the behavior of the swarm drove by the forces can be adjusted via selecting proper control parameters. The theoretical analysis of the swarm behavior proves the stability and convergence properties of the algorithm. We further make certain modifications upon the forces to improve the robustness of the swarm behavior in the presence of realistic implementation considerations. The considerations include obstacle avoidance, local minima, and deformation of the shape. Finally, detailed simulation results validate the efficiency of the proposed algorithm, and the direction of possible futrue work is discussed in the conclusions.

  12. The Effect of Dry Needling of the Trigger Points of Shoulder Muscles on Pain and Grip Strength in Patients with Lateral Epicondylitis: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Alireza Kheradmandi

    2015-09-01

    Full Text Available Background: Lateral epicondylitis, also known as tennis elbow, is the most common overuse syndrome of the elbow. The severity of pain may not be directly caused by tendinopathy of wrist extensors since trigger points of the shoulder muscles have a referral zone in the arm and elbow. Therefore the aim of this study was to evaluate the effect of dry needling of shoulder myofascial trigger points on wrist extensors muscles pain and function. Methods: Fourteen female patients with tennis elbow (aged 20 - 45 years old were recruited after primary evaluation by an orthopedist. They entered the study if they had pain in the lateral aspect of elbow of the dominant hand for more than 3 months along with the presence of myofascial trigger points in any muscles of supra spinatus, infra spinatus, sub scapularis or scalenes. Pain pressure threshold, maximal grip force and pain intensity of the hand extensors on lateral epicondyle of elbow were measured before and after treatment. Pain intensity was measured on a one to ten scale of visual analogue scale (VAS. A hand dynamometer used to measure the maximal grip force value of the affected hand in 0˚shoulder flexion/ abduction, 90˚ elbow extension and mid-poison of forearm in sitting position. A pressure algometer was applied on hand extensor muscles to define their trigger point sensitivity. For the control group, treatment regimens consisted of routine physical therapy of tennis elbow. This regime was accompanied by dry needling of mentioned muscles for the intervention group. Wilcoxon and Mann-Whitney non-parametric tests were used for statistical analysis. Results: Comparison of the results after intervention showed that the patients’ pain significantly decreased in both groups (P<0.001; but the patient’s PPT and grip force significantly increased solely in the intervention group (P<0.05. Mann Whitney test showed significant pain differences in both groups (P=0.001. The comparison of differences

  13. PICK1 interacts with ABP/GRIP to regulate AMPA receptor trafficking.

    Science.gov (United States)

    Lu, Wei; Ziff, Edward B

    2005-08-04

    PICK1 and ABP/GRIP bind to the AMPA receptor (AMPAR) GluR2 subunit C terminus. Transfer of the receptor from ABP/GRIP to PICK1, facilitated by GluR2 S880 phosphorylation, may initiate receptor trafficking. Here we report protein interactions that regulate these steps. The PICK1 BAR domain interacts intermolecularly with the ABP/GRIP linker II region and intramolecularly with the PICK1 PDZ domain. Binding of PKCalpha or GluR2 to the PICK1 PDZ domain disrupts the intramolecular interaction and facilitates the PICK1 BAR domain association with ABP/GRIP. Interference with the PICK1-ABP/GRIP interaction impairs S880 phosphorylation of GluR2 by PKC and decreases the constitutive surface expression of GluR2, the NMDA-induced endocytosis of GluR2, and recycling of internalized GluR2. We suggest that the PICK1 interaction with ABP/GRIP is a critical step in controlling GluR2 trafficking.

  14. Coming to grips with challenging behaviour: a cluster randomised controlled trial on the effects of a new care programme for challenging behaviour on burnout, job satisfaction and job demands of care staff on dementia special care units.

    Science.gov (United States)

    Zwijsen, S A; Gerritsen, D L; Eefsting, J A; Smalbrugge, M; Hertogh, C M P M; Pot, A M

    2015-01-01

    Caring for people with dementia in dementia special care units is a demanding job. Challenging behaviour is one of the factors influencing the job satisfaction and burnout of care staff. A care programme for the challenging behaviour of nursing home residents with dementia might, next to diminishing the challenging behaviour of residents, improve job satisfaction and reduce the care staff's feelings of burnout. To determine the effects of a care programme for the challenging behaviour of nursing home residents with dementia on the burnout, job satisfaction and job demands of care staff. The care programme was implemented according to a stepped wedge design in which care units were randomly divided over five groups with different time points of starting with implementation. 17 Dutch dementia special care units. Care staff members of the 17 units. The care programme consists of an education package and of various structured assessment tools that guide professionals through the multidisciplinary detection, analysis, treatment and evaluation of treatment of challenging behaviour. Burnout, job satisfaction and job demands were measured before implementation, halfway through the implementation process and after all the care units had implemented the care programme. Burnout was measured with the Dutch version of the Maslach burnout inventory (UBOS-C, three subscales); job satisfaction and job demands were measured with subscales of the Leiden Quality of Work Questionnaire. Mixed model analyses were used to determine effects. Care staff could not be blinded for the intervention. Of the 1441 questionnaires, 645 were returned (response 45%, 318 control measurements, 327 intervention measurements) by 380 unique care staff members. Significant effects were found on job satisfaction (0.93, 95% CI 0.48-1.38). On the other outcomes, no significant changes in the scores were found. Positive effects of using the Grip on Challenging behaviour care programme were found on job

  15. Obesity-related differences in neural correlates of force control.

    Science.gov (United States)

    Mehta, Ranjana K; Shortz, Ashley E

    2014-01-01

    Greater body segment mass due to obesity has shown to impair gross and fine motor functions and reduce balance control. While recent studies suggest that obesity may be linked with altered brain functions involved in fine motor tasks, this association is not well investigated. The purpose of this study was to examine the neural correlates of motor performance in non-obese and obese adults during force control of two upper extremity muscles. Nine non-obese and eight obese young adults performed intermittent handgrip and elbow flexion exertions at 30% of their respective muscle strengths for 4 min. Functional near infrared spectroscopy was employed to measure neural activity in the prefrontal cortex bilaterally, joint steadiness was computed using force fluctuations, and ratings of perceived exertions (RPEs) were obtained to assess perceived effort. Obesity was associated with higher force fluctuations and lower prefrontal cortex activation during handgrip exertions, while RPE scores remained similar across both groups. No obesity-related differences in neural activity, force fluctuation, or RPE scores were observed during elbow flexion exertions. The study is one of the first to examine obesity-related differences on prefrontal cortex activation during force control of the upper extremity musculature. The study findings indicate that the neural correlates of motor activity in the obese may be muscle-specific. Future work is warranted to extend the investigation to monitoring multiple motor-function related cortical regions and examining obesity differences with different task parameters (e.g., longer duration, increased precision demands, larger muscles, etc.).

  16. Força de preensão palmar e pinça digital em diferentes grupos de pilotos da Academia da Força Aérea brasileira Grip and pinch strength among different groups of Brazilian Air Force pilots

    Directory of Open Access Journals (Sweden)

    Gláucia Helena Gonçalves

    2010-06-01

    Full Text Available Pilotos da Academia de Força Aérea (AFA brasileira, durante vôos, realizam movimentos com grande solicitação da musculatura da mão que comanda o manche, o que pode modificar a força muscular. Este estudo teve por objetivo analisar as forças musculares isométricas de preensão palmar e pinças polpa-a-polpa, trípode e lateral de três grupos de pilotos da AFA. Foram avaliados 15 pilotos da Esquadrilha da Fumaça (EDA, 16 instrutores de vôo (PI e 6 pilotos em treinamento (PT, todos do sexo masculino. Para a avaliação, o posicionamento corporal dos pilotos seguiu a padronização da Sociedade Americana de Terapeutas da Mão e a ordem dos movimentos analisados foi predefinida, evitando fadiga muscular. A força muscular isométrica máxima foi coletada em uma contração sustentada por 6 segundos. Os resultados mostram diferenças significativas na preensão, com superioridade das mãos dominantes em relação às não-dominantes em todos os grupos, tendo ainda o grupo EDA obtido valores significativamente superiores em relação aos demais. Nas medidas da pinça trípode, o grupo EDA apresentou significativos valores superiores aos do grupo PT, sendo encontrados valores das mãos dominantes superiores aos das não-dominantes nos grupos EDA e PI. Conclui-se que o treino específico da musculatura da mão durante o vôo, a especificidade e o período de treinamento interferem na força muscular isométrica da mão.Pilots from Brazilian Air Force Academy (AFA perform strentgth- and accuracy-demanding hand movements, which may modify muscle strength. The aim of this study was to analyse hand isometric strength of grip and pulp-to-pulp, tripode and lateral pinch in three groups of male AFA pilots: ADS (Air Demonstration Squadron, n=15; IP (instructor pilots, n=16; and TP (training pilots, n=6. Pilots body positioning during tests followed the standards of the American Society of Hand Therapists; the sequence of assessed movements was

  17. Geometric Aspects of Force Controllability for a Swimming Model

    International Nuclear Information System (INIS)

    Khapalov, A. Y.

    2008-01-01

    We study controllability properties (swimming capabilities) of a mathematical model of an abstract object which 'swims' in the 2-D Stokes fluid. Our goal is to investigate how the geometric shape of this object affects the forces acting upon it. Such problems are of interest in biology and engineering applications dealing with propulsion systems in fluids

  18. Vibration control of an elastic strip by a singular force

    Indian Academy of Sciences (India)

    strip are changed by applying a lateral concentrated force to the plate. ... Predicting resonance frequency of plates is an important technological and scientific ... Ritz methods in a number of studies pertaining to control of flutter in aerospace ..... Bingham B, Atalla M J, Hagood N W 2001 Comparison of structural-acoustic ...

  19. Controlling propulsive forces in gait initiation in transfemoral amputees

    NARCIS (Netherlands)

    van Keeken, Helco G.; Vrieling, Aline H.; Hof, At L.; Halbertsma, Jan P. K.; Schoppen, Tanneke; Postema, Klaas; Otten, Bert

    During prosthetic gait initiation, transfemoral (TF) amputees control the spatial and temporal parameters that modulate the propulsive forces, the positions of the center of pressure (CoP), and the center of mass (CoM). Whether their sound leg or the prosthetic leg is leading, the TF amputees reach

  20. Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press.

    Science.gov (United States)

    Lockie, Robert G; Callaghan, Samuel J; Moreno, Matthew R; Risso, Fabrice G; Liu, Tricia M; Stage, Alyssa A; Birmingham-Babauta, Samantha A; Stokes, John J; Giuliano, Dominic V; Lazar, Adrina; Davis, DeShaun L; Orjalo, Ashley J

    2017-12-01

    The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM) traditional bench press (TBP) and close-grip bench press (CGBP). Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p velocity was greater for the CGBP (d = 0.50-1.29). The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982). TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931). TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704). TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980). Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements.

  1. Control of master-slave manipulator using virtual force

    International Nuclear Information System (INIS)

    Kosuge, Kazuhiro; Fukuda, Toshio; Itoh, Tomotaka; Sakamoto, Keizoh; Noma, Yasuo.

    1994-01-01

    We propose a control system for a master-slave manipulator system having a rate-controlled slave manipulator. In this system, the master manipulator is stiffness-controlled in the Cartesian coordinate system, and the slave manipulator is damping-controlled in the Cartesian coordinate system. The desired velocity of the slave arm is given by a displacement of the master arm from a nominal position. The operator feels virtual contact force from the environment because the contact force is proportional to the displacement when the slave arm motion is constrained by the environment. The proposed method is experimentally applied to manipulators with three degrees of freedom. The experimental results illustrate the validity of the proposed system. (author)

  2. Force-controlled patch clamp of beating cardiac cells.

    Science.gov (United States)

    Ossola, Dario; Amarouch, Mohamed-Yassine; Behr, Pascal; Vörös, János; Abriel, Hugues; Zambelli, Tomaso

    2015-03-11

    From its invention in the 1970s, the patch clamp technique is the gold standard in electrophysiology research and drug screening because it is the only tool enabling accurate investigation of voltage-gated ion channels, which are responsible for action potentials. Because of its key role in drug screening, innovation efforts are being made to reduce its complexity toward more automated systems. While some of these new approaches are being adopted in pharmaceutical companies, conventional patch-clamp remains unmatched in fundamental research due to its versatility. Here, we merged the patch clamp and atomic force microscope (AFM) techniques, thus equipping the patch-clamp with the sensitive AFM force control. This was possible using the FluidFM, a force-controlled nanopipette based on microchanneled AFM cantilevers. First, the compatibility of the system with patch-clamp electronics and its ability to record the activity of voltage-gated ion channels in whole-cell configuration was demonstrated with sodium (NaV1.5) channels. Second, we showed the feasibility of simultaneous recording of membrane current and force development during contraction of isolated cardiomyocytes. Force feedback allowed for a gentle and stable contact between AFM tip and cell membrane enabling serial patch clamping and injection without apparent cell damage.

  3. Models and control for force/torque sensors in robotics

    International Nuclear Information System (INIS)

    Johansson, Gert.

    1992-01-01

    One of the important problems in automatic assembly is the relative positioning accuracy between the parts in the assembly process. Inaccurate positions cause large insertion forces, wear and might damage the parts. They can also completely disable the assembly process. A solution to this problem is to detect the positioning error and to make a relevant adjustment of the position or path. This thesis presents a solution based on active feedback of force/torque data from a wrist mounted sensor. A task independent control algorithm has been realized through a sensor model concept. The sensor model includes an algorithm that transforms force/torque input to relevant motion of the end effector. The transformation is specified by a set of parameters e.g. desired forces, compliance and stopping criteria. The problem with gravity forces for varying end effector orientation is compensated by an algorithm, divided into three complexity levels. The compensation method includes a calibration sequence to ensure valid end effector properties to be used in the algorithm. A problem with available robot technology is bad integration possibilities for external sensors. To allow necessary modifications and expansions, an open and general control system architecture is proposed. The architecture is based in a computer workstation and transputers in pipeline for the robot specific operations. (au)

  4. GRIP DC-8 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP DC-8 Navigation and Housekeeping Data contains aircraft navigational data obtained during the GRIP campaign (15 Aug 2010 - 30 Sep 2010). The major goal was...

  5. Neuromechanical Control for Dynamic Bipedal Walking with Reduced Impact Forces

    DEFF Research Database (Denmark)

    Widenka, Johannes; Xiong, Xiaofeng; Matthias Braun, Jan

    2016-01-01

    Human walking emerges from an intricate interaction of nervous and musculoskeletal systems. Inspired by this principle, we integrate neural control and muscle-like mechanisms to achieve neuromechanical control of the biped robot RunBot. As a result, the neuromechanical controller enables RunBot t......Bot to perform more human-like walking and reduce impact force during walking, compared to original neural control. Moreover, it also generates adaptive joint motions of RunBot; thereby allowing it to deal with different terrains...

  6. Relationship between lung function and grip strength in older hospitalized patients: a pilot study

    Directory of Open Access Journals (Sweden)

    Holmes SJ

    2017-04-01

    Full Text Available Sarah J Holmes,1 Stephen C Allen,2,3 Helen C Roberts4,5 1Medicine and Elderly Care, Hampshire Hospitals NHS Foundation Trust, Winchester, 2Medicine and Geriatrics, The Royal Bournemouth Hospital and Christchurch Hospitals NHS Foundation Trust, Bournemouth, 3Centre of Postgraduate Medical Research and Education, Bournemouth University, Poole, 4Academic Geriatric Medicine, University of Southampton, 5University Hospital Southampton NHS Foundation Trust, Southampton, UK Objective: Older people with reduced respiratory muscle strength may be misclassified as having COPD on the basis of spirometric results. We aimed to evaluate the relationship between lung function and grip strength in older hospitalized patients without known airways disease.Methods: Patients in acute medical wards were recruited who were aged ≥70 years; no history, symptoms, or signs of respiratory disease; Mini Mental State Examination ≥24; willing and able to consent to participate; and able to perform hand grip and forced spirometry. Data including lung function (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], FEV1/FVC, peak expiratory flow rate [PEFR], and slow vital capacity [SVC], grip strength, age, weight, and height were recorded. Data were analyzed using descriptive statistics and linear regression unadjusted and adjusted (for age, height, and weight.Results: A total of 50 patients (20 men were recruited. Stronger grip strength in men was significantly associated with greater FEV1, but this was attenuated by adjustment for age, height, and weight. Significant positive associations were found in women between grip strength and both PEFR and SVC, both of which remained robust to adjustment.Conclusion: The association between grip strength and PEFR and SVC may reflect stronger patients generating higher intrathoracic pressure at the start of spirometry and pushing harder against thoracic cage recoil at end-expiration. Conversely, patients with

  7. Grip op werkstress. Mindfulness ontstresst maatschappelijk werkers

    Directory of Open Access Journals (Sweden)

    Jen van Horen

    2014-03-01

    Full Text Available Taking control over work related stress. Mindfulness destresses social workersStress is a major social problem. Due to the increasing workload and the content of the work, social workers are at risk to develop stress (symptoms. The physical and psychological consequences of prolonged stress are serious. By living healthy, optimize working conditions and applying mindfulness, stress can be reduced. Mindfulness is an effective and useful way to reduce stress. It increases the resistance of workers against stress, improves brainfunctions and therefore has a positive effect on the performance. These effects are great, but they are still weakly methodologically substantiated. A pilot project within the youthcare though, was enthusiastically received and proves to be effective against stress symptoms. The exercises that are part of this pilot fit well with the needs of employees. For organizations mindfulnesstrainings are a time-and cost-effective way of structural stress prevention.Grip op werkstress. Mindfulness ontstresst maatschappelijk werkersStress is een omvangrijk maatschappelijk probleem. Door de toenemende werkdruk en de inhoud van het werk zijn maatschappelijk werkers een risicogroep om stress en stressklachten te ontwikkelen. De fysieke en psychische gevolgen die langdurige stress met zich meebrengt zijn ernstig. Door gezond te leven, de arbeidsomstandigheden te optimaliseren en mindfulness toe te passen kan stress terug worden gedrongen. Mindfulness is een effectieve en bruikbare manier om stress te verminderen. Het vergroot de weerbaarheid van werknemers tegen stress, het verbetert de hersenwerking en heeft daardoor een positief effect op het functioneren. Grote effecten dus, maar wel nog methodologisch zwak onderbouwd. Een pilot binnen de jeugdzorg op het gebied van mindfulness is enthousiast ontvangen en blijkt effectief tegen stressklachten. De oefeningen die onderdeel uitmaken van deze pilot sluiten goed aan bij de behoeften van

  8. ANALYSIS OF POWER GRIP AND PINCH GRIP AMONG HEALTH CARE PROFESSIONALS

    Directory of Open Access Journals (Sweden)

    Zakariya M P

    2016-02-01

    Full Text Available Background: Grip and pinch strength are commonly employed indices of strength used in hand evaluations. Pinch grip and power grip strengths are used as indices of strength in hand therapy assessments. For all professions grip strength is an important criterion to be successful in their profession. Such phenomena may be explained by differences in nature of work, working environment, and objects workers handle. Method: 200 healthy subjects, satisfying the selection criteria were included and assessed with standardized procedure for power grip and pinch grip (lateral pinch, pad-pad, and tip-tip strength. They were divided in four groups, 50 group each according to profession i.e. medical surgeons, dentist, physiotherapists and nurses. Results: The mean power grip strength shows highly significant difference between medical vs. dental (p>0.01 and medical vs. physiotherapy group (p> 0.05 .The mean lateral pinch strength shows there is highly significant difference (p< 0.001 between dental vs. nursing profession and dental vs. physiotherapy group. No significant difference among other groups. The mean pad-pad pinch strength shows there is significant difference between dental vs. nursing (p< 0.05 and dental vs physiotherapy group (p< 0.05. The mean Tip-Tip pinch strength shows there is significant difference between dental vs nursing profession(p< 0.05 and dental vs. physiotherapy(p< 0.05. No significant different among other groups. Conclusion: Surgeons have highest power grip strength followed by Nursing, Physiotherapy and Dental professionals. Dentists have the maximum pinch strength in all three positions, followed by Surgeons, Nurses and Physiotherapists. Surgeons have maximum pinch strength next to Dentists.

  9. Forced excitation and active control for the measurement of fluid-elastic forces

    International Nuclear Information System (INIS)

    Caillaud, Sebastien

    1999-01-01

    The action of a fluid flow on a tubes bundle is commonly decomposed into a random turbulent excitation and a fluid-elastic excitation. The fluid-elastic forces which are coupled to the tubes movement can be experimentally determined from an analysis of the vibratory response of the structure excited by turbulent forces. For low flow velocities, the turbulent excitation can be insufficient to make the tube significantly vibrate and to permit a correct vibratory analysis. On the opposite side, the structure can become unstable for high flow velocities: the fluid-elastic forces make the fluid-structure damping system fall towards zero. Two experimental methods are proposed in order to extend the considered flow rate. An additional excitation force allows to increase the tube vibration level for improving the signal-noise ratio at low velocities. When the tube is submitted to fluid-elastic instability, an artificial damping contribution by active control allows to stabilize it. Methods are implemented on a flexible tube inserted into rigid tubes bundle water and water-air transverse flows. Two actuator technologies are used: an electromagnetic exciter and piezoelectric actuators. The additional excitation method shows that the fluid-elastic forces remain insignificant at low velocity single phase flow. With the active control method, it is possible to carry out tests beyond the fluid-elastic instability. In two-phase flow, the stabilization of the structure is observed for low vacuum rates. The obtained new results are analyzed with the literature expected results in terms of fluid-elastic coupling and turbulent excitation. (author) [fr

  10. G×E Interaction Influences Trajectories of Hand Grip Strength

    DEFF Research Database (Denmark)

    Petersen, Inge; Pedersen, Nancy L; Rantanen, Taina

    2016-01-01

    Age-related decline in grip strength predicts later life disability, frailty, lower well-being and cognitive change. While grip strength is heritable, genetic influence on change in grip strength has been relatively ignored, with non-shared environmental influence identified as the primary contri...

  11. Force control of a robot for surface contamination detection

    International Nuclear Information System (INIS)

    Petterson, B.J.; Jones, J.F.

    1987-01-01

    A system is under development at Sandia National Laboratories for use in understanding the issues relating to automated robotic handling of spent nuclear fuel shipping casks. The goal of robotic handling is reduction of personnel radiation exposure at the proposed geologic repositories. One of the major technology development areas has been the integration of sensors into the control of the robot system to allow operation in semi-structured environments. In particular, a multiaxis force sensor is used to make robot trajectory corrections based on the contact force between the robot and workpiece. This force feedback system allows contact swipes (smears) to be made on the cask surface in a repeatable manner. 8 refs., 3 figs

  12. Rate control and quality assurance during rhythmic force tracking.

    Science.gov (United States)

    Huang, Cheng-Ya; Su, Jyong-Huei; Hwang, Ing-Shiou

    2014-02-01

    Movement characteristics can be coded in the single neurons or in the summed activity of neural populations. However, whether neural oscillations are conditional to the frequency demand and task quality of rhythmic force regulation is still unclear. This study was undertaken to investigate EEG dynamics and behavior correlates during force-tracking at different target rates. Fourteen healthy volunteers conducted load-varying isometric abduction of the index finger by coupling the force output to sinusoidal targets at 0.5 Hz, 1.0 Hz, and 2.0 Hz. Our results showed that frequency demand significantly affected EEG delta oscillation (1-4 Hz) in the C3, CP3, CPz, and CP4 electrodes, with the greatest delta power and lowest delta peak around 1.5 Hz for slower tracking at 0.5 Hz. Those who had superior tracking congruency also manifested enhanced alpha oscillation (8-12 Hz). Alpha rhythms of the skilled performers during slow tracking spread through the whole target cycle, except for the phase of direction changes. However, the alpha rhythms centered at the mid phase of a target cycle with increasing target rate. In conclusion, our findings clearly suggest two advanced roles of cortical oscillation in rhythmic force regulation. Rate-dependent delta oscillation involves a paradigm shift in force control under different time scales. Phasic organization of alpha rhythms during rhythmic force tracking is related to behavioral success underlying the selective use of bimodal controls (feedback and feedforward processes) and the timing of attentional focus on the target's peak velocity. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Optimal feedback control of the forced van der Pol system

    International Nuclear Information System (INIS)

    Chagas, T.P.; Toledo, B.A.; Rempel, E.L.; Chian, A.C.-L.; Valdivia, J.A.

    2012-01-01

    A simple feedback control strategy for chaotic systems is investigated using the forced van der Pol system as an example. The strategy regards chaos control as an optimization problem, where the maximum magnitude Floquet multiplier of a target unstable periodic orbit (UPO) is used as a cost function that needs to be minimized. Thus, the method obtains the optimal control gain in terms of the stability of the target UPO. This strategy was recently proposed for the proportional feedback control (PFC) method. Here, it is extended to the highly popular delayed feedback control (DFC) method. Since the DFC method treats the system as a delay-differential equation whose phase space is infinite-dimensional, the characteristic multipliers are found through a truncation in the number of delayed states. Control of a target UPO is achieved for several values of the forcing amplitude. We compare the DFC and PFC methods in terms of stability of the controlled orbit, steady state error and control effort.

  14. Efeito da preensão manual sobre o equilíbrio de judocas Effect of hand grip on the balance of judokas

    Directory of Open Access Journals (Sweden)

    Jonathan Ache Dias

    2011-06-01

    Full Text Available O objetivo deste estudo foi verificar se existe efeito da preensão manual máxima (o ato de realizar ou não a preensão sobre o controle do equilíbrio de judocas em postura restrita, além de verificar se existe correlação entre a força de preensão manual (FPM e o controle do equilíbrio. Foram avaliados sete judocas com um dinamômetro e uma plataforma estabilométrica sendo mensuradas, concomitantemente, a FPM e o centro de pressão (CP. Foi verificado que até 80% da variabilidade do CP pode ser atrelada a preensão manual indicando que a mesma gera perturbações no controle do equilíbrio. Entretanto, foram encontradas correlações (r = 0,348 até 0,816 entre a FPM e o deslocamento do CP. Com isso pode-se concluir que, apesar da preensão manual gerar perturbações no equilíbrio, seu comportamento parece estar relacionado com os movimentos do corpo realizados para manter o equilíbrio, indicando uma possível correlação entre esses fenômenos.The purpose of this study was to verify if there is an effect of maximum hand grip (the act of performing or not the hand grip on the balance control of judokas in a restrict posture, and also to verify if there is a correlation between the hand grip strength (HGS and the balance control. Seven judokas were evaluated with a dynamometer and a stabilometric force platform, being measured, at the same time, the HGS and the center of pressure (COP. It was found that up to 80% of the COP variability was related to the hand grip demonstrating that it generates perturbations to the balance control. However, It was found correlations (r = 0,348 to 0,816 between de HGS and de COP displacement. With that, it can be concluded that, despite the hand grip generating perturbation on the balance, its behavior appears to be related to the body movements performed to sustain balance, indicating a possible correlation between this phenomenons.

  15. Longitudinal assessment of grip strength using bulb dynamometer in Duchenne Muscular Dystrophy

    Directory of Open Access Journals (Sweden)

    Tatiana M. Pizzato

    2014-07-01

    Full Text Available BACKGROUND: Grip strength is used to infer functional status in several pathological conditions, and the hand dynamometer has been used to estimate performance in other areas. However, this relationship is controversial in neuromuscular diseases and studies with the bulb dynamometer comparing healthy children and children with Duchenne Muscular Dystrophy (DMD are limited. OBJECTIVE: The evolution of grip strength and the magnitude of weakness were examined in boys with DMD compared to healthy boys. The functional data of the DMD boys were correlated with grip strength. METHOD: Grip strength was recorded in 18 ambulant boys with DMD (Duchenne Group, DG aged 4 to 13 years (mean 7.4±2.1 and 150 healthy volunteers (Control Group, CG age-matched using a bulb dynamometer (North Coast- NC70154. The follow-up of the DG was 6 to 33 months (3-12 sessions, and functional performance was verified using the Vignos scale. RESULTS: There was no difference between grip strength obtained by the dominant and non-dominant side for both groups. Grip strength increased in the CG with chronological age while the DG remained stable or decreased. The comparison between groups showed significant difference in grip strength, with CG values higher than DG values (confidence interval of 95%. In summary, there was an increment in the differences between the groups with increasing age. Participants with 24 months or more of follow-up showed a progression of weakness as well as maintained Vignos scores. CONCLUSIONS: The amplitude of weakness increased with age in the DG. The bulb dynamometer detected the progression of muscular weakness. Functional performance remained virtually unchanged in spite of the increase in weakness.

  16. Satellite Dynamic Damping via Active Force Control Augmentation

    Science.gov (United States)

    Varatharajoo, Renuganth

    2012-07-01

    An approach that incorporates the Active Force Control (AFC) technique into a conventional Proportional-Derivative (PD) controller is proposed for a satellite active dynamic damping towards a full attitude control. The AFC method has been established to facilitate a robust motion control of dynamical systems in the presence of disturbances, parametric uncertainties and changes that are commonly prevalent in the real-world environment. The usefulness of the method can be extended by introducing intelligent mechanisms to approximate the mass or inertia matrix of the dynamic system to trigger the compensation effect of the controller. AFC is a technique that relies on the appropriate estimation of the inertial or mass parameters of the dynamic system and the measurements of the acceleration and force signals induced by the system if practical implementation is ever considered. In AFC, it is shown that the system subjected to a number of disturbances remains stable and robust via the compensating action of the control strategy. We demonstrate that it is possible to design a spacecraft attitude feedback controller that will ensure the system dynamics set point remains unchanged even in the presence of the disturbances provided that the actual disturbances can be modeled effectively. In order to further facilitate this analysis, a combined energy and attitude control system (CEACS) is proposed as a model satellite attitude control actuator. All the governing equations are established and the proposed satellite attitude control architecture is made amenable to numerical treatments. The results show that the PD-AFC attitude damping performances are superiorly better than that of the solely PD type. It is also shown that the tunings of the AFC system gains are crucial to ensure a better attitude damping performance and this process is mandatory for AFC systems. Finally, the results demonstrate an important satellite dynamic damping enhancement capability using the AFC

  17. Hand grip endurance test relates to clinical state and prognosis in COPD patients better than 6-minute walk test distance

    Directory of Open Access Journals (Sweden)

    Kovarik M

    2017-12-01

    Full Text Available Miroslav Kovarik,1,2 Vera Joskova,1,2 Anna Patkova,1,2 Vladimir Koblizek,3 Zdenek Zadak,2 Miloslav Hronek1,2 1Department of Biological and Medical Sciences, Faculty of Pharmacy in Hradec Kralove, Charles University, Hradec Kralove, Czech Republic; 2Department of Research and Development, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic; 3Department of Pulmonary Medicine, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic Purpose: Patients with COPD present peripheral muscle dysfunction and atrophy, expressed as muscle strength and endurance reduction. The goal of this study was direct dynamometric assessment of hand grip endurance and strength in relation to the stage of disease, multidimensional predictors of mortality, and 6-minute walk test (6MWT. To the best of our knowledge, there has been no previous study determining these parameters.Patients and methods: In this observational study, 58 consecutive outpatients with stable COPD and 25 volunteers without respiratory problems were compared. All COPD subjects underwent a comprehensive examination to determine COPD severity, prognostic scales, and 6MWT. Body composition, basic spirometric parameters, and hand grip strength and endurance were determined in all study participants.Results: Patients in the COPD group had a 15% decrease in maximum strength (P=0.012 and a 28% decrease in area under the force/time curve (AUC of the endurance test (P<0.001 compared to the control group. Dynamometric parameters were significantly negatively associated with the stage of disease and values of multivariable prediction indexes, and positively associated with the results of 6MWT. In most cases, closer associations were found with AUC than with 6MWT and in the gender-specific groups.Conclusion: Both hand grip strength and endurance are impaired in COPD patients in comparison with the control group. In particular, AUC could be considered as an attractive option not only to

  18. A Multiposture Locomotor Training Device with Force-Field Control

    Directory of Open Access Journals (Sweden)

    Jianfeng Sui

    2014-11-01

    Full Text Available This paper introduces a multiposture locomotor training device (MPLTD with a closed-loop control scheme based on joint angle feedback, which is able to overcome various difficulties resulting from mechanical vibration and the weight of trainer to achieve higher accuracy trajectory. By introducing the force-field control scheme used in the closed-loop control, the device can obtain the active-constrained mode including the passive one. The MPLTD is mainly composed of three systems: posture adjusting and weight support system, lower limb exoskeleton system, and control system, of which the lower limb exoskeleton system mainly includes the indifferent equilibrium mechanism with two degrees of freedom (DOF and the driving torque is calculated by the Lagrangian function. In addition, a series of experiments, the weight support and the trajectory accuracy experiment, demonstrate a good performance of mechanical structure and the closed-loop control.

  19. Force Reflection Control for Master/Slave Tele-manipulators

    International Nuclear Information System (INIS)

    Kang, Min Sig; Kim, Doo Ho; Choi, Sun Il; Kim, Nam Hyung; Lee, Jong Bee

    2009-04-01

    This report concerns on a master/slave tele-manipulator which is used in highly hazardous hot cell. To design a force reflection and fine tracking control for the master-slave telemanipulator, the following has been carried out. (1) Variation of the moment of inertia of each link in the operating angle range, (2) Variation of the gratitational torque of each link in the operating angle range, (3) Dynamic characteristic analysis of the master-slave manipulator controlled by an output PD-control through a modal analysis, (4) Optimal static output feedback PD-control design by using modal analysis, (5) Controller design for each joint, (6) Adams-MatLab Simulink simulation model development. The results this project are as follows: (1) Program for analysis of the moment of inertia of each link in the operating angle range and simulation results, (2) Program for analysis of the gratitational torque of each link in the operating angle range and simulation results, (3) Dynamic characteristic of the master-slave manipulator controlled by an output PD-control through a modal analysis, (4) Program for designing optimal output PD-control by using modal analysis, (5) Controller designed for each joint, (6) Adams-MatLab Simulink simulation model, (7) Simulation results form output PD-control, etc

  20. Development of the first force-controlled robot for otoneurosurgery.

    Science.gov (United States)

    Federspil, Philipp A; Geisthoff, Urban W; Henrich, Dominik; Plinkert, Peter K

    2003-03-01

    In some surgical specialties (eg, orthopedics), robots are already used in the operating room for bony milling work. Otological surgery and otoneurosurgery may also greatly benefit from the enhanced precision of robotics. Experimental study on robotic milling of oak wood and human temporal bone specimen. A standard industrial robot with a six-degrees-of-freedom serial kinematics was used, with force feedback to proportionally control the robot speed. Different milling modes and characteristic path parameters were evaluated to generate milling paths based on computer-aided design (CAD) geometry data of a cochlear implant and an implantable hearing system. The best-suited strategy proved to be the spiral horizontal milling mode with the burr held perpendicular to the temporal bone surface. To reduce groove height, the distance between paths should equal half the radius of the cutting burr head. Because of the vibration of the robot's own motors, a high oscillation of the SD of forces was encountered. This oscillation dropped drastically to nearly 0 Newton (N) when the burr head made contact with the dura mater, because of its damping characteristics. The cutting burr could be kept in contact with the dura mater for an extended period without damaging it, because of the burr's blunt head form. The robot moved the burr smoothly according to the encountered resistances. The study reports the first development of a functional robotic milling procedure for otoneurosurgery with force-based speed control. Future plans include implementation of ultrasound-based local navigation and performance of robotic mastoidectomy.

  1. The interdigital brace and other grips for termite nest perforation by chimpanzees of the Goualougo Triangle, Republic of Congo.

    Science.gov (United States)

    Lesnik, Julie J; Sanz, Crickette M; Morgan, David B

    2015-06-01

    Studies of chimpanzee termite foraging enlighten our understanding of early hominin tool use not only by modeling the cognitive ability of our ancestors but also by emphasizing the possible role of social insects in the hominin diet. The chimpanzees of the Goualougo Triangle are known to have one of the largest and most complex tool repertoires reported for wild chimpanzees. One tool set habitually used by this population includes a perforating tool to penetrate the hard outer crust of elevated termite nests before fishing for termite prey with an herbaceous stem. Here, we report the variation present in the grips used on the perforating tool. Our analysis of video recordings of chimpanzee visitation to termite nests over a 3-year period shows that these chimpanzees use a variety of grips to navigate the challenges encountered in opening a termite nest. For situations in which the soil is most hardened, perforating requires force and a power grip is often used. When the soil in the passageway is loose, precision grips are suitable for the task. One of the preferred grips reported here is an interdigital brace, which has previously been described in studies of how some people hold a pencil. In this study, for the first time, the interdigital brace has been thoroughly described for chimpanzees. The various strategies and grips used during perforation emphasize the importance of termites as a nutritional resource that should be considered more strongly as a food used by early hominins. © 2015 Wiley Periodicals, Inc.

  2. Dextrous gripping in a hazardous environment

    International Nuclear Information System (INIS)

    Jongkind, W.

    1993-01-01

    Existing dextrous grippers are presented and compared, tasks to be performed in the hazardous environment are analyzed, and recommendations on gripper design and configuration are given. The outcome is a proposal for a dextrous gripper consisting of three antropomorphic fingers and an active palm. Sensor and actuator issues have been investigated and a selection of them has been made with respect to applicability in the hazardous environment. Theoretical contact issues were investigated and contacts have been modelled accordingly, followed by a kinematical analysis of the proposed gripper. Force and motion equations have been derived, and finger force distribution and computation has been analyzed. Grasp planning, the determination for a given task of a sequence of postures, to gurantee the safe and robust grasping of an object has been investigated. The determination of postures resulting in the designation of the number and categories of contact points before the fingers of the gripper contact the object is a matter of high-level grasping. The post-contact phase of the grasp, where set points for position and/or force have to be controlled, a matter of low-level grasp planning, has been investigated. The dissertation concluded with an investigation into the control of the gripper to achieve reliable grasps. The aim was to arrive at a controller that can comply with varying external forces and that can cope with imprecise known objects and imprecise task descriptions. Also the controlling of grasping forces as aimed at. The resulting gripper is radiation resistant. The methodology worked out in the dissertation is currently being applied to the design of a gripper able to operate in a hazardous nuclear environment. (orig./HP)

  3. Internet-Based Implementation of Non-Pharmacological Interventions of the "People Getting a Grip on Arthritis" Educational Program: An International Online Knowledge Translation Randomized Controlled Trial Design Protocol

    Science.gov (United States)

    Thomas, Roanne; De Angelis, Gino

    2015-01-01

    Background Rheumatoid arthritis (RA) affects 2.1% of the Australian population (1.5% males; 2.6% females), with the highest prevalence from ages 55 to over 75 years (4.4-6.1%). In Canada, RA affects approximately 0.9% of adults, and within 30 years that is expected to increase to 1.3%. With an aging population and a greater number of individuals with modifiable risk factors for chronic diseases, such as arthritis, there is an urgent need for co-care management of arthritic conditions. The increasing trend and present shifts in the health services and policy sectors suggest that digital information delivery is becoming more prominent. Therefore, it is necessary to further investigate the use of online resources for RA information delivery. Objective The objective is to examine the effect of implementing an online program provided to patients with RA, the People Getting a Grip on Arthritis for RA (PGrip-RA) program, using information communication technologies (ie, Facebook and emails) in combination with arthritis health care professional support and electronic educational pamphlets. We believe this can serve as a useful and economical method of knowledge translation (KT). Methods This KT randomized controlled trial will use a prospective randomized open-label blinded-endpoint design to compare four different intervention approaches of the PGrip-RA program to a control group receiving general electronic educational pamphlets self-management in RA via email. Depending on group allocation, links to the Arthritis Society PGrip-RA material will be provided either through Facebook or by email. One group will receive feedback online from trained health care professionals. The intervention period is 6 weeks. Participants will have access to the Internet-based material after the completion of the baseline questionnaires until the final follow-up questionnaire at 6 months. We will invite 396 patients from Canadian and Australian Arthritis Consumers’ Associations to

  4. Internet-based implementation of non-pharmacological interventions of the "people getting a grip on arthritis" educational program: an international online knowledge translation randomized controlled trial design protocol.

    Science.gov (United States)

    Brosseau, Lucie; Wells, George; Brooks-Lineker, Sydney; Bennell, Kim; Sherrington, Cathie; Briggs, Andrew; Sturnieks, Daina; King, Judy; Thomas, Roanne; Egan, Mary; Loew, Laurianne; De Angelis, Gino; Casimiro, Lynn; Toupin April, Karine; Cavallo, Sabrina; Bell, Mary; Ahmed, Rukhsana; Coyle, Doug; Poitras, Stéphane; Smith, Christine; Pugh, Arlanna; Rahman, Prinon

    2015-02-03

    Rheumatoid arthritis (RA) affects 2.1% of the Australian population (1.5% males; 2.6% females), with the highest prevalence from ages 55 to over 75 years (4.4-6.1%). In Canada, RA affects approximately 0.9% of adults, and within 30 years that is expected to increase to 1.3%. With an aging population and a greater number of individuals with modifiable risk factors for chronic diseases, such as arthritis, there is an urgent need for co-care management of arthritic conditions. The increasing trend and present shifts in the health services and policy sectors suggest that digital information delivery is becoming more prominent. Therefore, it is necessary to further investigate the use of online resources for RA information delivery. The objective is to examine the effect of implementing an online program provided to patients with RA, the People Getting a Grip on Arthritis for RA (PGrip-RA) program, using information communication technologies (ie, Facebook and emails) in combination with arthritis health care professional support and electronic educational pamphlets. We believe this can serve as a useful and economical method of knowledge translation (KT). This KT randomized controlled trial will use a prospective randomized open-label blinded-endpoint design to compare four different intervention approaches of the PGrip-RA program to a control group receiving general electronic educational pamphlets self-management in RA via email. Depending on group allocation, links to the Arthritis Society PGrip-RA material will be provided either through Facebook or by email. One group will receive feedback online from trained health care professionals. The intervention period is 6 weeks. Participants will have access to the Internet-based material after the completion of the baseline questionnaires until the final follow-up questionnaire at 6 months. We will invite 396 patients from Canadian and Australian Arthritis Consumers' Associations to participate using online recruitment

  5. Nonlinear force feedback control of piezoelectric-hydraulic pump actuator for automotive transmission shift control

    Science.gov (United States)

    Kim, Gi-Woo; Wang, K. W.

    2008-03-01

    In recent years, researchers have investigated the feasibility of utilizing piezoelectric-hydraulic pump based actuation systems for automotive transmission controls. This new concept could eventually reduce the complexity, weight, and fuel consumption of the current transmissions. In this research, we focus on how to utilize this new approach on the shift control of automatic transmissions (AT), which generally requires pressure profiling for friction elements during the operation. To illustrate the concept, we will consider the 1--> 2 up shift control using band brake friction elements. In order to perform the actuation force tracking for AT shift control, nonlinear force feedback control laws are designed based on the sliding mode theory for the given nonlinear system. This paper will describe the modeling of the band brake actuation system, the design of the nonlinear force feedback controller, and simulation and experimental results for demonstration of the new concept.

  6. Force control of a tri-layer conducting polymer actuator using optimized fuzzy logic control

    International Nuclear Information System (INIS)

    Itik, Mehmet; Sabetghadam, Mohammadreza; Alici, Gursel

    2014-01-01

    Conducting polymers actuators (CPAs) are potential candidates for replacing conventional actuators in various fields, such as robotics and biomedical engineering, due to their advantageous properties, which includes their low cost, light weight, low actuation voltage and biocompatibility. As these actuators are very suitable for use in micro-nano manipulation and in injection devices in which the magnitude of the force applied to the target is of crucial importance, the force generated by CPAs needs to be accurately controlled. In this paper, a fuzzy logic (FL) controller with a Mamdani inference system is designed to control the blocking force of a trilayer CPA with polypyrrole electrodes, which operates in air. The particle swarm optimization (PSO) method is employed to optimize the controller’s membership function parameters and therefore enhance the performance of the FL controller. An adaptive neuro-fuzzy inference system model, which can capture the nonlinear dynamics of the actuator, is utilized in the optimization process. The optimized Mamdani FL controller is then implemented on the CPA experimentally, and its performance is compared with a non-optimized fuzzy controller as well as with those obtained from a conventional PID controller. The results presented indicate that the blocking force at the tip of the CPA can be effectively controlled by the optimized FL controller, which shows excellent transient and steady state characteristics but increases the control voltage compared to the non-optimized fuzzy controllers. (paper)

  7. Constant Cutting Force Control for CNC Machining Using Dynamic Characteristic-Based Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Hengli Liu

    2015-01-01

    Full Text Available This paper presents a dynamic characteristic-based fuzzy adaptive control algorithm (DCbFACA to avoid the influence of cutting force changing rapidly on the machining stability and precision. The cutting force is indirectly obtained in real time by monitoring and extraction of the motorized spindle current, the feed speed is fuzzy adjusted online, and the current was used as a feedback to control cutting force and maintain the machining process stable. Different from the traditional fuzzy control methods using the experience-based control rules, and according to the complex nonlinear characteristics of CNC machining, the power bond graph method is implemented to describe the dynamic characteristics of process, and then the appropriate variation relations are achieved between current and feed speed, and the control rules are optimized and established based on it. The numerical results indicated that DCbFACA can make the CNC machining process more stable and improve the machining precision.

  8. Functional relationship between dominant and non-dominant hand in motor task - hand grip strength endurance

    Directory of Open Access Journals (Sweden)

    Kljajić Dragana

    2012-01-01

    Full Text Available The aim of this study was to determine the functional relationship between dominant and non-dominant hand in the strength endurance motor task - hand grip, in the referent population of healthy and young persons. For the purpose of the research we have implemented the method of isometric dynamometry and standardized hand grip test. The study included 48 participants, 23 of them being of female and 25 of male gender. The analysis of variance (ANOVA was used to determine the difference between the sets of variables in the function of gender and functional dimorphism, while the Bonferroni criterion was applied to determine the differences between pairs of individual variables. The difference between the maximum hand grip of dominant and non-dominant hand in female participants amounted to 9.28%, and in male ones 7.39% in favor of the dominant hand. There is no statistically significant difference between nondominant and dominant hand regarding the force endurance time aspect at 30%, 50% and 80% out of the maximum hand grip level, as well as at the absolute and relative force impulse indicators as an endurance measure. The value of gender dimorphism in relation to the absolute indicators of force momentum at 30%, 50% and 80% out of the maximum hand grip level in female participants is 0.9714, 0.9145, 0.9301, and in male participants 0.9515, 0.8264 and 0.8606. The force momentum indicators value at 30%, 50% and 80% out of the maximum hand grip level in female participants is ImpF30%=21167.58±6923.67 Ns, ImpF50%=10846.94±3800.56 Ns and ImpF80%=5438.46±1993.12 Ns, and in male participants ImpF30%=17734.03±6881.92 Ns, ImpF50%=13903.61±3437.76 Ns and ImpF80%=5117.53±1894.78 Ns. The obtained results can be used as the criteria for further research in special education and rehabilitation, medical and professional rehabilitation.

  9. Gripping means for fuel assemblies of nuclear reactor

    International Nuclear Information System (INIS)

    Batjukov, V.I.; Fadeev, A.I.; Shkhian, T.G.; Vjugov, O.N.

    1980-01-01

    The proposed gripping means for fuel assemblies of a nuclear reactor comprises a housing, whereupon there is movably mounted a slider provided with longitudinally extending slots to receive gripping jaws whose tails are pivotably secured to the housing of the gripping means. On one side, the end faces of the longitudinally extending slots are slanted with respect to the longitudinal axis of the gripping means and come in contact with the teeth of the gripping jaws provided on the end which is opposite to the tail, whereby the jaws open as the slider and housing of the gripping means moves relative to each other so that the teeth are received in an internal groove provided in the head of the fuel assembly

  10. Control of flow geometry using electromagnetic body forcing

    International Nuclear Information System (INIS)

    Rossi, L.; Bocquet, S.; Ferrari, S.; Garcia de la Cruz, J.M.; Lardeau, S.

    2009-01-01

    This paper presents conceptual experiments and simulations aiming at controlling flow geometries. Such flow design is performed by driving electromagnetically a shallow layer of brine, the forcing being generated by a transverse electrical current and different combinations of permanent magnets placed underneath the brine supporting wall. It is shown how different basic flow characteristics can be obtained with a single pair of magnets, by varying the angle with the electrical current. These basic flows are proposed as potential building blocks for advanced and complex flows studies. Three typical flow structures are presented to illustrate these building blocks. The discussion is then extended to multi-scale geometry by using blocks of various sizes. The flow is analysed using complementary experiments and numerical simulations. A good agreement is found between the 3D simulations and the experiments for both velocity and acceleration fields, which allows a higher degree of confidence in designing and modelling such flows. As the control of the flow geometry is important for mixing, in particular at low Reynolds number, we also illustrate the different stirring properties of the electromagnetically forced flows by comparing visualisations of passive scalars. They reveal complementary mixing properties for each of the building blocks.

  11. Lumbar extensor muscle force control is associated with disability in people with chronic low back pain.

    Science.gov (United States)

    Pranata, Adrian; Perraton, Luke; El-Ansary, Doa; Clark, Ross; Fortin, Karine; Dettmann, Tim; Brandham, Robert; Bryant, Adam

    2017-07-01

    The ability to control lumbar extensor force output is necessary for daily activities. However, it is unknown whether this ability is impaired in chronic low back pain patients. Similarly, it is unknown whether lumbar extensor force control is related to the disability levels of chronic low back pain patients. Thirty-three chronic low back pain and 20 healthy people performed lumbar extension force-matching task where they increased and decreased their force output to match a variable target force within 20%-50% maximal voluntary isometric contraction. Force control was quantified as the root-mean-square-error between participants' force output and target force across the entire, during the increasing and decreasing portions of the force curve. Within- and between-group differences in force-matching error and the relationship between back pain group's force-matching results and their Oswestry Disability Index scores were assessed using ANCOVA and linear regression respectively. Back pain group demonstrated more overall force-matching error (mean difference=1.60 [0.78, 2.43], Pback pain group demonstrated more force-matching error while increasing than decreasing force output (mean difference=1.74, Pback pain group (R 2 =0.19, P=0.006). Lumbar extensor muscle force control is compromised in chronic low back pain patients. Force-matching error predicts disability, confirming the validity of our force control protocol for chronic low back pain patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. The GRIP method for collaborative roadmapping workshops

    DEFF Research Database (Denmark)

    Piirainen, Kalle

    2015-01-01

    Technology roadmapping is a well-known tool for technology management, but practical advice for facilitating collaborative roadmapping workshops is relatively scarce. To cater for this need, we have designed a method for collaborative roadmapping, dubbed the GRIP method, for facilitating group work...... in TRM workshops. The design is based on establish best practices in facilitation and our experiences with the method suggest it is a feasible tool for technology managers. The benefits of the method are that it enables engaging a diverse group of individuals to the roadmapping process effectively even...... during a short workshop session and facilitates shared understanding on the technology management issues....

  13. Relationships between Mechanical Variables in the Traditional and Close-Grip Bench Press

    Directory of Open Access Journals (Sweden)

    Lockie Robert G.

    2017-12-01

    Full Text Available The study aim was to determine relationships between mechanical variables in the one-repetition maximum (1RM traditional bench press (TBP and close-grip bench press (CGBP. Twenty resistance-trained men completed a TBP and CGBP 1RM. The TBP was performed with the preferred grip; the CGBP with a grip width of 95% biacromial distance. A linear position transducer measured: lift distance and duration; work; and peak and mean power, velocity, and force. Paired samples t-tests (p < 0.05 compared the 1RM and mechanical variables for the TBP and CGBP; effect sizes (d were also calculated. Pearson’s correlations (r; p < 0.05 computed relationships between the TBP and CGBP. 1RM, lift duration, and mean force were greater in the TBP (d = 0.30-3.20. Peak power and velocity was greater for the CGBP (d = 0.50-1.29. The 1RM TBP correlated with CGBP 1RM, power, and force (r = 0.685-0.982. TBP work correlated with CGBP 1RM, lift distance, power, force, and work (r = 0.542-0.931. TBP power correlated with CGBP 1RM, power, force, velocity, and work (r = 0.484-0.704. TBP peak and mean force related to CGBP 1RM, power, and force (r = 0.596-0.980. Due to relationships between the load, work, power, and force for the TBP and CGBP, the CGBP could provide similar strength adaptations to the TBP with long-term use. The velocity profile for the CGBP was different to that of the TBP. The CGBP could be used specifically to improve high-velocity, upper-body pushing movements.

  14. Virtual grasping: closed-loop force control using electrotactile feedback.

    Science.gov (United States)

    Jorgovanovic, Nikola; Dosen, Strahinja; Djozic, Damir J; Krajoski, Goran; Farina, Dario

    2014-01-01

    Closing the control loop by providing somatosensory feedback to the user of a prosthesis is a well-known, long standing challenge in the field of prosthetics. Various approaches have been investigated for feedback restoration, ranging from direct neural stimulation to noninvasive sensory substitution methods. Although there are many studies presenting closed-loop systems, only a few of them objectively evaluated the closed-loop performance, mostly using vibrotactile stimulation. Importantly, the conclusions about the utility of the feedback were partly contradictory. The goal of the current study was to systematically investigate the capability of human subjects to control grasping force in closed loop using electrotactile feedback. We have developed a realistic experimental setup for virtual grasping, which operated in real time, included a set of real life objects, as well as a graphical and dynamical model of the prosthesis. We have used the setup to test 10 healthy, able bodied subjects to investigate the role of training, feedback and feedforward control, robustness of the closed loop, and the ability of the human subjects to generalize the control to previously "unseen" objects. Overall, the outcomes of this study are very optimistic with regard to the benefits of feedback and reveal various, practically relevant, aspects of closed-loop control.

  15. Virtual Grasping: Closed-Loop Force Control Using Electrotactile Feedback

    Directory of Open Access Journals (Sweden)

    Nikola Jorgovanovic

    2014-01-01

    Full Text Available Closing the control loop by providing somatosensory feedback to the user of a prosthesis is a well-known, long standing challenge in the field of prosthetics. Various approaches have been investigated for feedback restoration, ranging from direct neural stimulation to noninvasive sensory substitution methods. Although there are many studies presenting closed-loop systems, only a few of them objectively evaluated the closed-loop performance, mostly using vibrotactile stimulation. Importantly, the conclusions about the utility of the feedback were partly contradictory. The goal of the current study was to systematically investigate the capability of human subjects to control grasping force in closed loop using electrotactile feedback. We have developed a realistic experimental setup for virtual grasping, which operated in real time, included a set of real life objects, as well as a graphical and dynamical model of the prosthesis. We have used the setup to test 10 healthy, able bodied subjects to investigate the role of training, feedback and feedforward control, robustness of the closed loop, and the ability of the human subjects to generalize the control to previously “unseen” objects. Overall, the outcomes of this study are very optimistic with regard to the benefits of feedback and reveal various, practically relevant, aspects of closed-loop control.

  16. GRIP LIDAR ATMOSPHERIC SENSING EXPERIMENT (LASE) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Lidar Atmospheric Sensing Experiment (LASE) dataset was collected by NASA's Lidar Atmospheric Sensing Experiment (LASE) system, which is an airborne...

  17. Position Control of Linear Synchronous Motor Drives with Exploitation of Forced Dynamics Control Principles

    Directory of Open Access Journals (Sweden)

    Jan Vittek

    2004-01-01

    Full Text Available Closed-loop position control of mechanisms directly driven by linear synchronous motors with permanent magnets is presented. The control strategy is based on forced dynamic control, which is a form of feedback linearisation, yielding a non-liner multivariable control law to obtain a prescribed linear speed dynamics together with the vector control condition of mutal orthogonality between the stator current and magnetic flux vectors (assuming perfect estimates of the plant parameters. Outer position control loop is closed via simple feedback with proportional gain. Simulations of the design control sysstem, including the drive with power electronic switching, predict the intended drive performance.

  18. Evaluating Information Assurance Control Effectiveness on an Air Force Supervisory Control and Data Acquisition (SCADA) System

    Science.gov (United States)

    2011-03-01

    Byres, E. J., Lowe, J. (2004). The Myths and facts behind cyber security risks for industrial control systems . Berlin, Germany: VDE 2004 Congress...ACQUISITION (SCADA) SYSTEM THESIS Jason R. Nielsen, Major, USAF AFIT/GCO/ENG/11-10 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE...DATA ACQUISITION (SCADA) SYSTEM THESIS Presented to the Faculty Department of Electrical and Computer Engineering Graduate School of

  19. Memory-guided force control in healthy younger and older adults.

    Science.gov (United States)

    Neely, Kristina A; Samimy, Shaadee; Blouch, Samantha L; Wang, Peiyuan; Chennavasin, Amanda; Diaz, Michele T; Dennis, Nancy A

    2017-08-01

    Successful performance of a memory-guided motor task requires participants to store and then recall an accurate representation of the motor goal. Further, participants must monitor motor output to make adjustments in the absence of visual feedback. The goal of this study was to examine memory-guided grip force in healthy younger and older adults and compare it to performance on behavioral tasks of working memory. Previous work demonstrates that healthy adults decrease force output as a function of time when visual feedback is not available. We hypothesized that older adults would decrease force output at a faster rate than younger adults, due to age-related deficits in working memory. Two groups of participants, younger adults (YA: N = 32, mean age 21.5 years) and older adults (OA: N = 33, mean age 69.3 years), completed four 20-s trials of isometric force with their index finger and thumb, equal to 25% of their maximum voluntary contraction. In the full-vision condition, visual feedback was available for the duration of the trial. In the no vision condition, visual feedback was removed for the last 12 s of each trial. Participants were asked to maintain constant force output in the absence of visual feedback. Participants also completed tasks of word recall and recognition and visuospatial working memory. Counter to our predictions, when visual feedback was removed, younger adults decreased force at a faster rate compared to older adults and the rate of decay was not associated with behavioral performance on tests of working memory.

  20. Effects of oncoming target velocities on rapid force production and accuracy of force production intensity and timing.

    Science.gov (United States)

    Ohta, Yoichi

    2017-12-01

    The present study aimed to clarify the effects of oncoming target velocities on the ability of rapid force production and accuracy and variability of simultaneous control of both force production intensity and timing. Twenty male participants (age: 21.0 ± 1.4 years) performed rapid gripping with a handgrip dynamometer to coincide with the arrival of an oncoming target by using a horizontal electronic trackway. The oncoming target velocities were 4, 8, and 12 m · s -1 , which were randomly produced. The grip force required was 30% of the maximal voluntary contraction. Although the peak force (Pf) and rate of force development (RFD) increased with increasing target velocity, the value of the RFD to Pf ratio was constant across the 3 target velocities. The accuracy of both force production intensity and timing decreased at higher target velocities. Moreover, the intrapersonal variability in temporal parameters was lower in the fast target velocity condition, but constant variability in 3 target velocities was observed in force intensity parameters. These results suggest that oncoming target velocity does not intrinsically affect the ability for rapid force production. However, the oncoming target velocity affects accuracy and variability of force production intensity and timing during rapid force production.

  1. Predictability, Force and (Anti-)Resonance in Complex Object Control.

    Science.gov (United States)

    Maurice, Pauline; Hogan, Neville; Sternad, Dagmar

    2018-04-18

    Manipulation of complex objects as in tool use is ubiquitous and has given humans an evolutionary advantage. This study examined the strategies humans choose when manipulating an object with underactuated internal dynamics, such as a cup of coffee. The object's dynamics renders the temporal evolution complex, possibly even chaotic, and difficult to predict. A cart-and-pendulum model, loosely mimicking coffee sloshing in a cup, was implemented in a virtual environment with a haptic interface. Participants rhythmically manipulated the virtual cup containing a rolling ball; they could choose the oscillation frequency, while the amplitude was prescribed. Three hypotheses were tested: 1) humans decrease interaction forces between hand and object; 2) humans increase the predictability of the object dynamics; 3) humans exploit the resonances of the coupled object-hand system. Analysis revealed that humans chose either a high-frequency strategy with anti-phase cup-and-ball movements or a low-frequency strategy with in-phase cup-and-ball movements. Counter Hypothesis 1, they did not decrease interaction force; instead, they increased the predictability of the interaction dynamics, quantified by mutual information, supporting Hypothesis 2. To address Hypothesis 3, frequency analysis of the coupled hand-object system revealed two resonance frequencies separated by an anti-resonance frequency. The low-frequency strategy exploited one resonance, while the high-frequency strategy afforded more choice, consistent with the frequency response of the coupled system; both strategies avoided the anti-resonance. Hence, humans did not prioritize interaction force, but rather strategies that rendered interactions predictable. These findings highlight that physical interactions with complex objects pose control challenges not present in unconstrained movements.

  2. Precision grip responses to unexpected rotational perturbations scale with axis of rotation.

    Science.gov (United States)

    De Gregorio, Michael; Santos, Veronica J

    2013-04-05

    It has been established that rapid, pulse-like increases in precision grip forces ("catch-up responses") are elicited by unexpected translational perturbations and that response latency and strength scale according to the direction of linear slip relative to the hand as well as gravity. To determine if catch-up responses are elicited by unexpected rotational perturbations and are strength-, axis-, and/or direction-dependent, we imposed step torque loads about each of two axes which were defined relative to the subject's hand: the distal-proximal axis away from and towards the subject's palm, and the grip axis which connects the two fingertips. Precision grip responses were dominated initially by passive mechanics and then by active, unimodal catch-up responses. First dorsal interosseous activity, marking the start of the catch-up response, began 71-89 ms after the onset of perturbation. The onset latency, shape, and duration (217-231 ms) of the catch-up response were not affected by the axis, direction, or magnitude of the rotational perturbation, while strength was scaled by axis of rotation and slip conditions. Rotations about the grip axis that tilted the object away from the palm and induced rotational slip elicited stronger catch-up responses than rotations about the distal-proximal axis that twisted the object between the digits. To our knowledge, this study is the first to investigate grip responses to unexpected torque loads and to show characteristic, yet axis-dependent, catch-up responses for conditions other than pure linear slip. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Nutritional status is the major factor affecting grip strength of African HIV patients before and during antiretroviral treatment.

    Science.gov (United States)

    Filteau, S; PrayGod, G; Woodd, S L; Friis, H; Heimburger, D C; Koethe, J R; Kelly, P; Kasonka, L; Rehman, A M

    2017-10-01

    Low grip strength is a marker of frailty and a risk factor for mortality among HIV patients and other populations. We investigated factors associated with grip strength in malnourished HIV patients at referral to ART, and at 12 weeks and 2-3 years after starting ART. The study involved HIV-infected Zambian and Tanzanian participants recruited to the NUSTART trial when malnourished (body mass index <18.5 kg/m 2 ) and requiring ART. The relationship of grip strength to nutritional, infectious and demographic factors was assessed by multivariable linear regression at referral for ART (n = 1742) and after 12 weeks (n = 778) and 2-3 years of ART (n = 273). In analyses controlled only for sex, age and height, most nutrition and infection-related variables were associated with grip strength. However, in multivariable analyses, consistent associations were seen for fat-free mass index, mid-upper arm circumference, haemoglobin and systolic blood pressure, and a variable association with fat mass index in men. C-reactive protein and CD4 count had limited independent effects on grip strength, while receiving tuberculosis treatment was associated with weaker grip strength. In this population of originally malnourished HIV patients, poor grip strength was more strongly and independently associated with nutritional than with infection and inflammation variables. Programmes to improve health and survival of HIV patients should incorporate nutritional assessment and management and could use grip strength as a functional indicator of improving nutrition. © 2017 John Wiley & Sons Ltd.

  4. Grip Strength Is Associated With Cognitive Performance in Schizophrenia and the General Population: A UK Biobank Study of 476559 Participants.

    Science.gov (United States)

    Firth, Joseph; Stubbs, Brendon; Vancampfort, Davy; Firth, Josh A; Large, Matthew; Rosenbaum, Simon; Hallgren, Mats; Ward, Philip B; Sarris, Jerome; Yung, Alison R

    2018-04-19

    Handgrip strength may provide an easily-administered marker of cognitive functional status. However, further population-scale research examining relationships between grip strength and cognitive performance across multiple domains is needed. Additionally, relationships between grip strength and cognitive functioning in people with schizophrenia, who frequently experience cognitive deficits, has yet to be explored. Baseline data from the UK Biobank (2007-2010) was analyzed; including 475397 individuals from the general population, and 1162 individuals with schizophrenia. Linear mixed models and generalized linear mixed models were used to assess the relationship between grip strength and 5 cognitive domains (visual memory, reaction time, reasoning, prospective memory, and number memory), controlling for age, gender, bodyweight, education, and geographical region. In the general population, maximal grip strength was positively and significantly related to visual memory (coefficient [coeff] = -0.1601, standard error [SE] = 0.003), reaction time (coeff = -0.0346, SE = 0.0004), reasoning (coeff = 0.2304, SE = 0.0079), number memory (coeff = 0.1616, SE = 0.0092), and prospective memory (coeff = 0.3486, SE = 0.0092: all P reasoning (P > .1). Grip strength is significantly associated with cognitive functioning in the general population and individuals with schizophrenia, particularly for working memory and processing speed. Future research should establish directionality, examine if grip strength also predicts functional and physical health outcomes in schizophrenia, and determine whether interventions which improve muscular strength impact on cognitive and real-world functioning.

  5. Reorganised force control in elbow pain patients during isometric wrist extension

    DEFF Research Database (Denmark)

    Mista, Christian Ariel; Monterde, Sonia; Inglés, Montserrat

    2018-01-01

    INTRODUCTION: Reorganised force control may be an important adaptation following painful traumas. In this study, force control adaptations were assessed in elbow pain patients. Increasing the contraction demand may overcome pain interference on the motor control and as such act as an internal...... voluntary contraction. Pressure pain thresholds were recorded at the lateral epicondyle and tibialis anterior muscle. Contraction force was recorded using a three-directional force transducer. Participants performed contractions according with visual feedback of the task-related force intensity (main...... direction of wrist extension) and another set of contractions with feedback of the three force directions. Going from the simple to the detailed force feedback will increase the demand of the motor task. Force steadiness in all 3 dimensions and force direction was extracted. RESULTS: Compared with controls...

  6. The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating

    Directory of Open Access Journals (Sweden)

    Mohamed Z. Ramadan

    2017-12-01

    Full Text Available Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation of 30.44 (5.35 years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI, hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove. The data were analyzed using the Shapiro–Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C had a significant influence on grip when compared to medium (25 °C and high (45 °C hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves.

  7. The Effects of Industrial Protective Gloves and Hand Skin Temperatures on Hand Grip Strength and Discomfort Rating.

    Science.gov (United States)

    Ramadan, Mohamed Z

    2017-12-04

    Daily working activities and functions require a high contribution of hand and forearm muscles in executing grip force. To study the effects of wearing different gloves on grip strength, under a variety of hand skin temperatures, an assessment of the maximum grip strength was performed with 32 healthy male workers with a mean age (standard deviation) of 30.44 (5.35) years wearing five industrial gloves at three hand skin temperatures. Their ages and anthropometric characteristics including body mass index (BMI), hand length, hand width, hand depth, hand palm, and wrist circumference were measured. The hand was exposed to different bath temperatures (5 °C, 25 °C, and 45 °C) and hand grip strength was measured using a Jamar hydraulic hand dynamometer with and without wearing the gloves (chemical protection glove, rubber insulating glove, anti-vibration impact glove, cotton yarn knitted glove, and RY-WG002 working glove). The data were analyzed using the Shapiro-Wilk test, Pearson correlation coefficient, Tukey test, and analysis of variance (ANOVA) of the within-subject design analysis. The results showed that wearing gloves significantly affected the maximum grip strength. Wearing the RY-WG002 working glove produced a greater reduction on the maximum grip when compared with the bare hand, while low temperatures (5 °C) had a significant influence on grip when compared to medium (25 °C) and high (45 °C) hand skin temperatures. In addition, participants felt more discomfort in both environmental extreme conditions. Furthermore, they reported more discomfort while wearing neoprene, rubber, and RY-WG002 working gloves.

  8. Real-time tracking control of electro-hydraulic force servo systems using offline feedback control and adaptive control.

    Science.gov (United States)

    Shen, Gang; Zhu, Zhencai; Zhao, Jinsong; Zhu, Weidong; Tang, Yu; Li, Xiang

    2017-03-01

    This paper focuses on an application of an electro-hydraulic force tracking controller combined with an offline designed feedback controller (ODFC) and an online adaptive compensator in order to improve force tracking performance of an electro-hydraulic force servo system (EHFS). A proportional-integral controller has been employed and a parameter-based force closed-loop transfer function of the EHFS is identified by a continuous system identification algorithm. By taking the identified system model as a nominal plant model, an H ∞ offline design method is employed to establish an optimized feedback controller with consideration of the performance, control efforts, and robustness of the EHFS. In order to overcome the disadvantage of the offline designed controller and cope with the varying dynamics of the EHFS, an online adaptive compensator with a normalized least-mean-square algorithm is cascaded to the force closed-loop system of the EHFS compensated by the ODFC. Some comparative experiments are carried out on a real-time EHFS using an xPC rapid prototype technology, and the proposed controller yields a better force tracking performance improvement. Copyright © 2016. Published by Elsevier Ltd.

  9. Control of forced vibrations of mechanical structures by an electromagnetic controller with a permanent magnet

    DEFF Research Database (Denmark)

    Stein, George Juraj; Darula, Radoslav; Sorokin, Sergey

    2012-01-01

    A theoretical analysis of an electromagnetic vibration controller is presented. The analyzed device consists of a pot-type iron core with a coil and a permanent magnet as a source of constant magnetic flux. The magnetic circuit is closed by a yoke, excited by an external harmonic mechanical force....... The so generated magnetic flux variation induces alternating voltage in the electric circuit, which is dissipated in a shunt resistor. The induced current driven through the coil generates magnetic force, which damps the excitation force and changes the damped natural frequency of the oscillatory system....... Due to the hysteretic effects in the magnetic material the internal losses influence the overall system’s performance. A mathematical model of the force balance in the oscillatory system is derived in a simplified, linearised form. The electric as well as mechanical system is modelled using lumped...

  10. Grip-pattern recognition: Applied to a smart gun

    NARCIS (Netherlands)

    Shang, X.

    2008-01-01

    In our work the verification performance of a biometric recognition system based on grip patterns, as part of a smart gun for use by the police ocers, has been investigated. The biometric features are extracted from a two-dimensional pattern of the pressure, exerted on the grip of a gun by the hand

  11. Biometric verification based on grip-pattern recognition

    NARCIS (Netherlands)

    Veldhuis, Raymond N.J.; Bazen, A.M.; Kauffman, J.A.; Hartel, Pieter H.; Delp, Edward J.; Wong, Ping W.

    This paper describes the design, implementation and evaluation of a user-verification system for a smart gun, which is based on grip-pattern recognition. An existing pressure sensor consisting of an array of 44 x 44 piezoresistive elements is used to measure the grip pattern. An interface has been

  12. Algorithm Design for Grip-Pattern Verification in Smart Gun

    NARCIS (Netherlands)

    Shang, X.; Veldhuis, Raymond N.J.; Bazen, A.M.; Ganzevoort, W.P.T.

    2005-01-01

    The Secure Grip project1 focuses on the development of a hand-grip pattern recognition system, as part of the smart gun. Its target customer is the police. To explore the authentication performance of this system, we collected data from a group of police officers, and made authentication simulations

  13. Biometric verification based on grip-pattern recognition

    NARCIS (Netherlands)

    Veldhuis, Raymond N.J.; Bazen, A.M.; Kauffman, J.A.; Hartel, Pieter H.

    This paper describes the design, implementation and evaluation of a user-verification system for a smart gun, which is based on grip-pattern recognition. An existing pressure sensor consisting of an array of 44 £ 44 piezoresistive elements is used to measure the grip pattern. An interface has been

  14. Operational Command and Control: Lessons for Today's Joint Force from Grenada, Somalia, and Kosovo

    National Research Council Canada - National Science Library

    Foraker III, Joseph C

    2007-01-01

    This paper examines operational command and control issues encountered during Operation Urgent Fury in Grenada, the deployment of Task Force Ranger in Mogadishu, Somalia, and Operation Allied Force in Kosovo...

  15. Grip strength and quality of life in the second half of life: hope as a moderator.

    Science.gov (United States)

    Gum, Amber M; Segal-Karpas, Dikla; Avidor, Sharon; Ayalon, Liat; Bodner, Ehud; Palgi, Yuval

    2017-09-28

    The purpose of the current study was to investigate grip strength, hope, and their interaction as predictors of quality of life four years later in a nationally representative sample of older adults. Data were derived from the first (2005-2006) and second wave (2009) of the Israeli component of the Survey of Health Ageing and Retirement in Europe (SHARE; N = 344). Hope was measured by three items from the Hope   Scale, and quality of life was measured by the CASP-12 (Control, Autonomy, Self-Realization, and Pleasure). Multiple regression analyses were conducted. Grip strength at T1 predicted QoL in T2, but hope was not a significant predictor. Furthermore, hope moderated the effect of handgrip on QoL, such that the effect was weaker for higher levels of hope. As hypothesized, hope acted as a moderator, such that poor grip strength was associated with worse QoL for less hopeful older adults, but grip strength was not associated with QoL for more hopeful older adults. Findings are consistent with a theoretical conceptualization of hope as a buffer between physical challenges and negative outcomes like QoL. Encouraging a hopeful perspective could enhance QoL for older adults with decreased muscle strength.

  16. EFFECT OF ECCENTRIC EXERCISE PROGRAMME ON PAIN AND GRIP STRENGTH FOR SUBJECTS WITH MEDIAL EPICONDYLITIS

    Directory of Open Access Journals (Sweden)

    Mishra Prashant Akhilesh

    2014-04-01

    Full Text Available Background and Objective: Therapeutic eccentric exercise may provide both a structural and functional benefit during tendinopathy rehabilitation. The objective is to find the effect of eccentric exercises on improvement of pain and grip strength for subjects with Medial Epicondylitis. Method: Pre to post test experimental study design randomized thirty subjects with medial epicondylitis, 15 each into Group A and Group B. Group B subjects were treated with conventional therapy and Eccentric exercises. Group A subjects were treated with conventional therapy. Results: When means of post intervention were compared using Independent ‘t’ between groups there was no statistically significant difference in improvements obtained in VAS scores and grip strength. There was a statistically significant change in means of VAS score and Grip strength when means were analyzed by using Paired‘t’ test and Wilcoxon signed rank test within the groups with positive percentage of change. Conclusion: It is concluded that four weeks of Eccentric Exercise Programme combined with conventional therapy shown significant effect on improving pain and Grip strength, however the improvement obtained has no difference when compared with control conventional treatment for Subjects with Medial Epicondylitis.

  17. Force Control for a Pneumatic Cylinder Using Generalized Predictive Controller Approach

    Directory of Open Access Journals (Sweden)

    Ahmad ’Athif Mohd Faudzi

    2014-01-01

    Full Text Available Pneumatic cylinder is a well-known device because of its high power to weight ratio, easy use, and environmental safety. Pneumatic cylinder uses air as its power source and converts it to a possible movement such as linear and rotary movement. In order to control the pneumatic cylinder, controller algorithm is needed to control the on-off solenoid valve with encoder and pressure sensor as the feedback inputs. In this paper, generalized predictive controller (GPC is proposed as the control strategy for the pneumatic cylinder force control. To validate and compare the performance, proportional-integral (PI controller is also presented. Both controllers algorithms GPC and PI are developed using existing linear model of the cylinder from previous research. Results are presented in simulation and experimental approach using MATLAB-Simulink as the platform. The results show that the GPC is capable of fast response with low steady state error and percentage overshoot compared to PI.

  18. Force feedback delay affects perception of stiffness but not action, and the effect depends on the hand used but not on the handedness.

    Science.gov (United States)

    Leib, Raz; Rubin, Inbar; Nisky, Ilana

    2018-05-16

    Interaction with an object often requires the estimation of its mechanical properties. We examined whether the hand that is used to interact with the object and their handedness affected people's estimation of these properties using stiffness estimation as a test case. We recorded participants' responses on a stiffness discrimination of a virtual elastic force field and the grip force applied on the robotic device during the interaction. In half of the trials, the robotic device delayed the participants' force feedback. Consistent with previous studies, delayed force feedback biased the perceived stiffness of the force field. Interestingly, in both left-handed and right-handed participants, for the delayed force field, there was even less perceived stiffness when participants used their left hand than their right hand. This result supports the idea that haptic processing is affected by laterality in the brain, not by handedness. Consistent with previous studies, participants adjusted their applied grip force according to the correct size and timing of the load force regardless of the hand that was used, the handedness, or the delay. This suggests that in all these conditions, participants were able to form an accurate internal representation of the anticipated trajectory of the load force (size and timing) and that this representation was used for accurate control of grip force independently of the perceptual bias. Thus, these results provide additional evidence for the dissociation between action and perception in the processing of delayed information.

  19. Stop Blaming Disasters on Forces Beyond Our Control

    Energy Technology Data Exchange (ETDEWEB)

    Matalucci, R.V.

    1999-04-09

    As we enter the new millennium, let us recognize that the losses resulting from natural or malevolent events that cause major property damage, severe injuries, and unnecessary death are not always due to forces beyond our control. We can prevent these losses by changing the way we think and act about design and construction projects. New tools, technologies, and techniques can improve structural safety, security, and reliability and protect owners, occupants, and users against loss and casualties. Hurricane Mitch, the African embassy bombings, the ice storms in Canada and the northeastern US last winter, the Oklahoma City bombing, flooding and earthquakes in California, tornadoes and flooding in Florida, and wildfires in the Southwest are threats to the safety and security of the public and the reliability of our constructed environment. Today's engineering design community must recognize these threats and address them in our standards, building codes, and designs. We know that disasters will continue to strike and we must reduce their impact on the public. We must demand and create innovative solutions that assure a higher level of structural performance when disasters strike.

  20. Grip Strength Survey Based on Hand Tool Usage

    Directory of Open Access Journals (Sweden)

    Erman ÇAKIT

    2016-12-01

    Full Text Available Hand grip strength is broadly used for performing tasks involving equipment in production and processing activities. Most professionals in this field rely on grip strength to perform their tasks. There were three main aims of this study: i determining various hand grip strength measurements for the group of hand tool users, ii investigating the effects of height, weight, age, hand dominance, body mass index, previous Cumulative Trauma Disorder (CTD diagnosis, and hand tool usage experience on hand grip strength, and iii comparing the obtained results with existing data for other populations. The study groups comprised 71 healthy male facility workers. The values of subjects’ ages was observed between 26 and 74 years. The data were statistically analyzed to assess the normality of data and the percentile values of grip strength. The results of this study demonstrate that there were no significance differences noted between dominant and non-dominant hands. However, there were highly significant differences between the CTD group and the other group. Hand grip strength for the dominant hand was positively correlated to height, weight, and body mass index, and negatively correlated to age and tool usage experience. Hand dominance, height, weight, body mass index, age and tool usage experience should be considered when establishing normal values for grip strength.

  1. Hybrid Force and Position Control Strategy of Robonaut Performing Object Transfer Task

    Directory of Open Access Journals (Sweden)

    Chen Gang

    2018-01-01

    Full Text Available This paper proposes a coordinated hybrid force/position control strategy of robonaut performing object transfer operation. Firstly, the constraint relationships between robonaut and object are presented. Base on them, the unified dynamic model of the robonaut and object is established to design the hybrid force/position control method. The movement, the internal force and the external constraint force of the object are considered as the control targets of the control system. Finally, a MATLAB simulation of the robonaut performing object transfer task verifies the correctness and effectiveness of the proposed method. The results show that all the targets can be control accurately by using the method proposed in this paper. The presented control method can control both internal and external forces while maintaining control accuracy, which is a common control strategy.

  2. Control of thumb force using surface functional electrical stimulation and muscle load sharing

    Science.gov (United States)

    2013-01-01

    Background Stroke survivors often have difficulties in manipulating objects with their affected hand. Thumb control plays an important role in object manipulation. Surface functional electrical stimulation (FES) can assist movement. We aim to control the 2D thumb force by predicting the sum of individual muscle forces, described by a sigmoidal muscle recruitment curve and a single force direction. Methods Five able bodied subjects and five stroke subjects were strapped in a custom built setup. The forces perpendicular to the thumb in response to FES applied to three thumb muscles were measured. We evaluated the feasibility of using recruitment curve based force vector maps in predicting output forces. In addition, we developed a closed loop force controller. Load sharing between the three muscles was used to solve the redundancy problem having three actuators to control forces in two dimensions. The thumb force was controlled towards target forces of 0.5 N and 1.0 N in multiple directions within the individual’s thumb work space. Hereby, the possibilities to use these force vector maps and the load sharing approach in feed forward and feedback force control were explored. Results The force vector prediction of the obtained model had small RMS errors with respect to the actual measured force vectors (0.22±0.17 N for the healthy subjects; 0.17±0.13 N for the stroke subjects). The stroke subjects showed a limited work range due to limited force production of the individual muscles. Performance of feed forward control without feedback, was better in healthy subjects than in stroke subjects. However, when feedback control was added performances were similar between the two groups. Feedback force control lead, especially for the stroke subjects, to a reduction in stationary errors, which improved performance. Conclusions Thumb muscle responses to FES can be described by a single force direction and a sigmoidal recruitment curve. Force in desired direction can be

  3. An intelligent control scheme for precise tip-motion control in atomic force microscopy.

    Science.gov (United States)

    Wang, Yanyan; Hu, Xiaodong; Xu, Linyan

    2016-01-01

    The paper proposes a new intelligent control method to precisely control the tip motion of the atomic force microscopy (AFM). The tip moves up and down at a high rate along the z direction during scanning, requiring the utilization of a rapid feedback controller. The standard proportional-integral (PI) feedback controller is commonly used in commercial AFMs to enable topography measurements. The controller's response performance is determined by the set of the proportional (P) parameter and the integral (I) parameter. However, the two parameters cannot be automatically altered simultaneously according to the scanning speed and the surface topography during continuors scanning, leading to an inaccurate measurement. Thus a new intelligent controller combining the fuzzy controller and the PI controller is put forward in the paper. The new controller automatically selects the most appropriate PI parameters to achieve a fast response rate on basis of the tracking errors. In the experimental setup, the new controller is realized with a digital signal process (DSP) system, implemented in a conventional AFM system. Experiments are carried out by comparing the new method with the standard PI controller. The results demonstrate that the new method is more robust and effective for the precise tip motion control, corresponding to the achievement of a highly qualified image by shortening the response time of the controller. © Wiley Periodicals, Inc.

  4. Internal and external force-based impedance control for cooperative manipulation

    NARCIS (Netherlands)

    Heck, D.J.F.; Kostic, D.; Denasi, A.; Nijmeijer, H.

    2013-01-01

    An asymptotically stable cascaded control algorithm is proposed for cooperative manipulation of a common object. This algorithm controls motion and internal forces of the object, as well as the contact forces between the object and environment. The motion of each manipulator is controlled using an

  5. Controlled evaluation of silver nanoparticle dissolution using atomic force microscopy.

    Science.gov (United States)

    Kent, Ronald D; Vikesland, Peter J

    2012-07-03

    Incorporation of silver nanoparticles (AgNPs) into an increasing number of consumer products has led to concern over the potential ecological impacts of their unintended release to the environment. Dissolution is an important environmental transformation that affects the form and concentration of AgNPs in natural waters; however, studies on AgNP dissolution kinetics are complicated by nanoparticle aggregation. Herein, nanosphere lithography (NSL) was used to fabricate uniform arrays of AgNPs immobilized on glass substrates. Nanoparticle immobilization enabled controlled evaluation of AgNP dissolution in an air-saturated phosphate buffer (pH 7.0, 25 °C) under variable NaCl concentrations in the absence of aggregation. Atomic force microscopy (AFM) was used to monitor changes in particle morphology and dissolution. Over the first day of exposure to ≥10 mM NaCl, the in-plane AgNP shape changed from triangular to circular, the sidewalls steepened, the in-plane radius decreased by 5-11 nm, and the height increased by 6-12 nm. Subsequently, particle height and in-plane radius decreased at a constant rate over a 2-week period. Dissolution rates varied linearly from 0.4 to 2.2 nm/d over the 10-550 mM NaCl concentration range tested. NaCl-catalyzed dissolution of AgNPs may play an important role in AgNP fate in saline waters and biological media. This study demonstrates the utility of NSL and AFM for the direct investigation of unaggregated AgNP dissolution.

  6. Visually aided force control with fuzzy parameter tuning

    OpenAIRE

    Çallı, Berk; Calli, Berk

    2008-01-01

    Vision and force sensors provide rich information which can enable robots to execute complex tasks. The integration of these two types of sensors may prove very useful in many industrial robotic applications, as well as for the robots that operate in environments where humans live. Vision sensors give robots the ability to operate in complex and dynamic environments. With force sensors contacts can be detected, and manipulation tasks can be done without the risk of damaging the workpiece. The...

  7. Force-controlled adjustment of car body fixtures

    OpenAIRE

    Keller, Carsten

    2014-01-01

    Production technology in modern car body assembling is affected by highly automated and complex facilities. However, in mounting car body assemblies adjustments are always necessary to react on quality instabilities of the input parts. Today these adjustments are made according to experience and with a high content of manual operation. This paper describes an innovative method that detects part deformations in a force sensitive way following the works of Dr. Muck, who developed a force sensit...

  8. In-depth Study on Cylinder Wake Controlled by Lorentz Force

    International Nuclear Information System (INIS)

    Zhang Hui; Fan Bao-Chun; Chen Zhi-Hua

    2011-01-01

    The underlying mechanisms of the electromagnetic control of cylinder wake are investigated and discussed. The effects of Lorentz force are found to be composed of two parts, one is its direct action on the cylinder (the wall Lorentz force) and the other is applied to the fluid (called the field Lorentz force) near the cylinder surface. Our results show that the wall Lorentz force can generate thrust and reduce the drag; the field Lorentz force increases the drag. However, the cylinder drag is dominated by the wall Lorentz force. In addition, the field Lorentz force above the upper surface decreases the lift, while the upper wall Lorentz force increases it. The total lift is dominated by the upper wall Lorentz force. (fundamental areas of phenomenology(including applications))

  9. Workspace Safe Operation of a Force- or Impedance-Controlled Robot

    Science.gov (United States)

    Abdallah, Muhammad E. (Inventor); Hargrave, Brian (Inventor); Yamokoski, John D. (Inventor); Strawser, Philip A. (Inventor)

    2013-01-01

    A method of controlling a robotic manipulator of a force- or impedance-controlled robot within an unstructured workspace includes imposing a saturation limit on a static force applied by the manipulator to its surrounding environment, and may include determining a contact force between the manipulator and an object in the unstructured workspace, and executing a dynamic reflex when the contact force exceeds a threshold to thereby alleviate an inertial impulse not addressed by the saturation limited static force. The method may include calculating a required reflex torque to be imparted by a joint actuator to a robotic joint. A robotic system includes a robotic manipulator having an unstructured workspace and a controller that is electrically connected to the manipulator, and which controls the manipulator using force- or impedance-based commands. The controller, which is also disclosed herein, automatically imposes the saturation limit and may execute the dynamic reflex noted above.

  10. Progress on the interface between UPP and CPRHS (Cask and Plug Remote Handling System) tractor/gripping tool for ITER

    International Nuclear Information System (INIS)

    Rosa, Elena V.; Rios, Luis; Queral, Vicente

    2013-01-01

    Highlights: ► UPP interface requirements in the plug RH extraction/insertion for ITER. ► Analyze of maximum misalignment between port duct and port cell. ► Friction study between plug skids and VV port/ramp rails during the plug transfer. ► Definition of the tolerance in the plug skids to avoid the plug jamming. ► Concepts of gripping tools based on one gripping point and avoiding force feedback. -- Abstract: EFDA finances a training programme called Goal Oriented Training Programme for Remote Handling (GOT RH), whose goal is to train engineers in Remote Handling for ITER. As part of this training programme, the conceptual design of the mechanical interface between Upper Port Plug (UPP) and Cask and Plug Remote Handling System (CPRHS) as well as the conceptual design of the needed tools for UPP Remote Handling is carried out. The paper presents the conceptual design of the UPP/Gripping Tool Interface. This includes the conceptual design of the gripping tool for introducing/removing the UPP in/from the ITER port and the mechanical features on both sides of the UPP/Gripping Tool Interface (e.g. alignment features, mechanical connectors, fasteners). In order to develop the design of the interface between UPP and CPRHS it is necessary to first identify the functional requirements of the Transfer Cask System (TCS) and the CPRHS, such as required degrees of freedom (DoF), required performances of system, geometrical constraints, loading conditions, alignment requirements, RAMI requirements. These requirements are the input data for the design of the interface between UPP and gripping tool and some of them are also described in the paper

  11. Effect of skin hydration on the dynamics of fingertip gripping contact.

    Science.gov (United States)

    André, T; Lévesque, V; Hayward, V; Lefèvre, P; Thonnard, J-L

    2011-11-07

    The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

  12. GRIP BARBADOS/CAPE VERDE RADIOSONDE V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Barbados/Cape Verde radiosonde data set consists of generally two soundings per day (06Z and 12Z) launched from Barbados, and one sounding per day (12Z)...

  13. GRIP DOPPLER AEROSOL WIND LIDAR (DAWN) V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The GRIP Doppler Aerosol WiNd Lidar (DAWN) Dataset was collected by the Doppler Aerosol WiNd (DAWN), a pulsed lidar, which operated aboard a NASA DC-8 aircraft...

  14. Getting a grip on affordances, attention and visual fields

    OpenAIRE

    Linden, Lotje van der; Theeuwes, Jan; Ellis, Rob

    2013-01-01

    van der Linden, L., Theeuwes, J., & Ellis, R. (2012). Getting a grip on affordances, attention, and visual fields. Poster presented at the 2012 William James Graduate School Symposium, Amsterdam, The Netherlands.

  15. GRIP DC-8 NAVIGATION AND HOUSEKEEPING DATA V1

    Data.gov (United States)

    National Aeronautics and Space Administration — This dataset contains aircraft navigational data obtained during the GRIP campaign (15 Aug 2010 - 30 Sep 2010). The NASA DC-8 is outfitted with a navigational...

  16. Learning to push and learning to move: The adaptive control of contact forces

    Directory of Open Access Journals (Sweden)

    Maura eCasadio

    2015-11-01

    Full Text Available To be successful at manipulating objects one needs to apply simultaneously well controlled movements and contact forces. We present a computational theory of how the brain may successfully generate a vast spectrum of interactive behaviors by combining two independent processes. One process is competent to control movements in free space and the other is competent to control contact forces against rigid constraints. Free space and rigid constraints are singularities at the boundaries of a continuum of mechanical impedance. Within this continuum, forces and motions occur in compatible pairs connected by the equations of Newtonian dynamics. The force applied to an object determines its motion. Conversely, inverse dynamics determine a unique force trajectory from a movement trajectory. In this perspective, we describe motor learning as a process leading to the discovery of compatible force/motion pairs. The learned compatible pairs constitute a local representation of the environment's mechanics. Experiments on force field adaptation have already provided us with evidence that the brain is able to predict and compensate the forces encountered when one is attempting to generate a motion. Here, we tested the theory in the dual case, i.e. when one attempts at applying a desired contact force against a simulated rigid surface. If the surface becomes unexpectedly compliant, the contact point moves as a function of the applied force and this causes the applied force to deviate from its desired value. We found that, through repeated attempts at generating the desired contact force, subjects discovered the unique compatible hand motion. When, after learning, the rigid contact was unexpectedly restored, subjects displayed after effects of learning, consistent with the concurrent operation of a motion control system and a force control system. Together, theory and experiment support a new and broader view of modularity in the coordinated control of forces and

  17. Initial Effect of Taping Technique on Wrist Extension and Grip Strength and Pain of Individuals with Lateral Epicondylitis

    Directory of Open Access Journals (Sweden)

    Alireza Shamsoddini

    2010-04-01

    Full Text Available Objectives: Aim of this study is to investigate the initial effect of taping technique on wrist extension and grip strength and pain of Individuals with tennis elbow. Methods: fifteen patients (10 men and 5 women with 42.53 years on their dominant arm participated in this study. Outcome measures were wrist extension and grip strength and pain taken before and immediately after application of tape. The unaffected arm served as a control. Used of hand-held dynamometer and jammar dynamometer for evaluated of wrist extension and grip strength. Also, visual analog scale (VAS used for evaluated of pain Results: Among the variables, significant differences were found in wrist extension strength between effected and unaffected arm (P=0.006. Also, changes in grip strength shows statically significant improve in effect arm than unaffected arm (P=0.001. Changes in pain in impaired arm were positive. Discussion: Taping technique, as applied in this study demonstrated an impressive effect on wrist extension and grip strength and pain in individuals with tennis elbow. Therefore, it is recommended that this method may be useful in the management of this condition during exercise and functional rehabilitation.

  18. Modeling and boundary force control of microcantilevers utilized in atomic force microscopy for cellular imaging and characterization

    Science.gov (United States)

    Eslami, Sohrab

    the proposed Euler-Bernoulli model, a more comprehensive model is developed by modeling the probe dynamics and including the effects of the rotary inertia and shear deformation under the same proposed tip-sample interaction force. An extensive comparative study between the Euler-Bernoulli and Timoshenko beam assumptions is conducted for different conditions including different base-excitation amplitudes and higher modes. The results underline that the comprehensive Timoshenko model unveils the effects of the nonlinear interaction force better than the Euler-Bernoulli beam model. In addition to extensive modeling efforts on the microcantilever and its interaction with sample, an adaptive control framework is developed in order to make the microcantilever's tip follow a desired trajectory. This trajectory can further be considered as an important path acquired by the path planning techniques to manipulate the nanoparticles. There is a base excitation considered for this model and can be considered as an input force control to excite the probe by taking advantage of flexibility of the cantilever despite its complexity and under existence of the external nonlinear interaction forces between the tip and sample's surface. When building such complicated controller on top of the proposed comprehensive model, the results could be extended to study a macro-micro hybrid rigid-flexible model of a microrobot to mimic the realistic behavior of the MM3ARTM microrobot. The MM3ARTM microrobot is equipped with a piezoresistive layer which functions as a force sensor and is capable of measuring very slight forces as small as micro to nano-Newton. Two types of controllers are investigated for the case of the tip force control. Lyapunov-based PD and robust adaptive controllers are developed for this purpose and their performances and stabilities are compared. In the experimental part, a platform for performing the automated nanomanipulation and real-time cellular imaging is developed by

  19. An intelligent active force control algorithm to control an upper extremity exoskeleton for motor recovery

    Science.gov (United States)

    Hasbullah Mohd Isa, Wan; Taha, Zahari; Mohd Khairuddin, Ismail; Majeed, Anwar P. P. Abdul; Fikri Muhammad, Khairul; Abdo Hashem, Mohammed; Mahmud, Jamaluddin; Mohamed, Zulkifli

    2016-02-01

    This paper presents the modelling and control of a two degree of freedom upper extremity exoskeleton by means of an intelligent active force control (AFC) mechanism. The Newton-Euler formulation was used in deriving the dynamic modelling of both the anthropometry based human upper extremity as well as the exoskeleton that consists of the upper arm and the forearm. A proportional-derivative (PD) architecture is employed in this study to investigate its efficacy performing joint-space control objectives. An intelligent AFC algorithm is also incorporated into the PD to investigate the effectiveness of this hybrid system in compensating disturbances. The Mamdani Fuzzy based rule is employed to approximate the estimated inertial properties of the system to ensure the AFC loop responds efficiently. It is found that the IAFC-PD performed well against the disturbances introduced into the system as compared to the conventional PD control architecture in performing the desired trajectory tracking.

  20. PC-based digital feedback control for scanning force microscope

    International Nuclear Information System (INIS)

    Mohd Ashhar Khalid

    2002-01-01

    In the past, most digital feedback implementation for scanned-probe microscope were based on a digital signal processor (DSP). At present DSP plug-in card with the input-output interface module is still expensive compared to a fast pentium PC motherboard. For a magnetic force microscope (MFM) digital feedback has an advantage where the magnetic signal can be easily separated from the topographic signal. In this paper, a simple low-cost PC-based digital feedback and imaging system for Scanning Force Microscope (SFM) is presented. (Author)

  1. Optimization of Easy Atomic Force Microscope (ezAFM) Controls for Semiconductor Nanostructure Profiling

    Science.gov (United States)

    2017-09-01

    ARL-MR-0965 ● SEP 2017 US Army Research Laboratory Optimization of Easy Atomic Force Microscope (ezAFM) Controls for... Optimization of Easy Atomic Force Microscope (ezAFM) Controls for Semiconductor Nanostructure Profiling by Satwik Bisoi Science and...REPORT TYPE Memorandum Report 3. DATES COVERED (From - To) 2017 July 05–2017 August 18 4. TITLE AND SUBTITLE Optimization of Easy Atomic Force

  2. Hybrid Force Control Based on ICMAC for an Astronaut Rehabilitative Training Robot

    OpenAIRE

    Lixun Zhang; Yupeng Zou; Lan Wang; Xinping Pei

    2012-01-01

    A novel Astronaut Rehabilitative Training Robot (ART) based on a cable‐driven mechanism is represented in this paper. ART, a typical passive force servo system, can help astronauts to bench press in a microgravity environment. The purpose of this paper is to design controllers to eliminate the surplus force caused by an astronaut’s active movements. Based on the dynamics modelling of the cable‐driven unit, a hybrid force controller based on improved credit assignment CMAC (ICMAC) is presented...

  3. Dynamics modeling for parallel haptic interfaces with force sensing and control.

    Science.gov (United States)

    Bernstein, Nicholas; Lawrence, Dale; Pao, Lucy

    2013-01-01

    Closed-loop force control can be used on haptic interfaces (HIs) to mitigate the effects of mechanism dynamics. A single multidimensional force-torque sensor is often employed to measure the interaction force between the haptic device and the user's hand. The parallel haptic interface at the University of Colorado (CU) instead employs smaller 1D force sensors oriented along each of the five actuating rods to build up a 5D force vector. This paper shows that a particular manipulandum/hand partition in the system dynamics is induced by the placement and type of force sensing, and discusses the implications on force and impedance control for parallel haptic interfaces. The details of a "squaring down" process are also discussed, showing how to obtain reduced degree-of-freedom models from the general six degree-of-freedom dynamics formulation.

  4. Control over multiscale mixing in broadband-forced turbulence

    NARCIS (Netherlands)

    Kuczaj, Arkadiusz K.; Geurts, Bernardus J.

    2008-01-01

    The effects of explicit flow modulation on the dispersion of a passive scalar field are studied. Broadband forcing is applied to homogeneous isotropic turbulence to modulate the energy cascading and alter the kinetic energy spectrum. Consequently, a manipulation of turbulent flow can be achieved

  5. FORCE STRUCTURE: Better Management Controls Are Needed to Oversee the Army's Modular Force and Expansion Initiatives and Improve Accountability for Results

    National Research Council Canada - National Science Library

    2007-01-01

    .... For this report, GAO assessed to what extent the Army has accomplished the following: (1) implemented and established management controls for its modular force and force expansion initiatives, and (2...

  6. Study on Characteristics of Hydraulic Servo System for Force Control of Hydraulic Robots

    International Nuclear Information System (INIS)

    Kim, Hyo-gon; Han, Changsoo; Lee, Jong-won; Park, Sangdeok

    2015-01-01

    Because a hydraulic actuator has high power and force densities, this allows the weight of the robot's limbs to be reduced. This allows for good dynamic characteristics and high energy efficiency. Thus, hydraulic actuators are used in some exoskeleton robots and quadrupedal robots that require high torque. Force control is useful for robot compliance with a user or environment. However, force control of a hydraulic robot is difficult because a hydraulic servo system is highly nonlinear from a control perspective. In this study, a nonlinear model was used to develop a simulation program for a hydraulic servo system consisting of a servo valve, transmission lines, and a cylinder. The problems and considerations with regard to the force control performance for a hydraulic servo system were investigated. A force control method using the nonlinear model was proposed, and its effect was evaluated with the simulation program

  7. Study on Characteristics of Hydraulic Servo System for Force Control of Hydraulic Robots

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyo-gon; Han, Changsoo [Hanyang University, Seoul (Korea, Republic of); Lee, Jong-won [Korea University of Science and Technology, Seoul (Korea, Republic of); Park, Sangdeok [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)

    2015-02-15

    Because a hydraulic actuator has high power and force densities, this allows the weight of the robot's limbs to be reduced. This allows for good dynamic characteristics and high energy efficiency. Thus, hydraulic actuators are used in some exoskeleton robots and quadrupedal robots that require high torque. Force control is useful for robot compliance with a user or environment. However, force control of a hydraulic robot is difficult because a hydraulic servo system is highly nonlinear from a control perspective. In this study, a nonlinear model was used to develop a simulation program for a hydraulic servo system consisting of a servo valve, transmission lines, and a cylinder. The problems and considerations with regard to the force control performance for a hydraulic servo system were investigated. A force control method using the nonlinear model was proposed, and its effect was evaluated with the simulation program.

  8. Control Design of Active Magnetic Bearings for Rotors Subjected to Destabilising Seal Forces - Theory & Experiment

    DEFF Research Database (Denmark)

    Lauridsen, Jonas Skjødt

    . At present, there is no generally accepted method for determination of dynamic seal forces. Therefore, large uncertainties must be expected when modelling dynamic seal forces and consequently also in rotor-dynamic stability analysis. This thesis focuses on i) closed loop identification of uncertain AMB...... parameters, ii) closed loop identification of unknown stiffness and damping coefficients of a dynamicseal model and iii) the design of AMB controllers to handle dynamic seal forces. Controllers that can guarantee stability and performance in the presence of uncertainseal forces are of special interest...... the uncertaintiesin seal forces and for LPV control synthesis, to compensate for known changes in seal forces due to changes in operating conditions. A rotor dynamic test facility with a rigid rotor, two radial AMBs and one annular test seal is used for i) closed loop identification of parameters in the AMB...

  9. Muscular forearm activation in hand-grip tasks with superimposition of mechanical vibrations.

    Science.gov (United States)

    Fattorini, L; Tirabasso, A; Lunghi, A; Di Giovanni, R; Sacco, F; Marchetti, E

    2016-02-01

    The purpose of this paper is to evaluate the muscular activation of the forearm, with or without vibration stimuli at different frequencies while performing a grip tasks of 45s at various level of exerted force. In 16 individuals, 9 females and 7 males, the surface electromyogram (EMG) of extensor carpi radialis longus and the flexor carpi ulnari muscles were assessed. At a short latency from onset EMG, RMS and the level of MU synchronization were assessed to evaluate the muscular adaptations. Whilst a trend of decay of EMG Median frequency (MDFd) was employed as an index of muscular fatigue. Muscular tasks consists of the grip of an instrumented handle at a force level of 20%, 30%, 40%, 60% of the maximum voluntary force. Vibration was supplied by a shaker to the hand in mono-frequential waves at 20, 30, 33 and 40Hz. In relation to EMG, RMS and MU synchronization, the muscular activation does not seem to change with the superimposition of the mechanical vibrations, on the contrary a lower MDFd was observed at 33Hz than in absence of vibration. This suggests an early muscular fatigue induced by vibration due to the fact that 33Hz is a resonance frequency for the hand-arm system. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Corticomuscular coherence during hand gripping with DBS and medication in PD patients

    DEFF Research Database (Denmark)

    Sridharan, Kousik Sarathy; Højlund, Andreas; Johnsen, Erik Lisbjerg

    Deep brain stimulation (DBS) effectively alleviates the motor symptoms in Parkinson’s disease (PD) although its effect mechanism is still unclear. CMC is reduced in PD patients but restorable with medication, while DBS variably affects CMC in advanced PD patients. We recorded magnetoencephalography...... (MEG) from six PD patients performing hand gripping during DBS ON and medicated (levodopa, MED ON) conditions and from ten age-matched healthy controls. Participants performed isotonic contractions (hand gripping) with their right hand, and electromyography (EMG) was recorded from the extensor...... digitorum communis muscle with a belly-tendon montage. We calculated the mean-squared coherence between MEG and the rectified EMG signals. For each group and condition, we selected the maximum CMC value in the beta range (13-30 Hz) within the average of an a priori selection of nine left sensorimotor...

  11. Research of a New 6-Dof Force Feedback Hand Controller System

    Directory of Open Access Journals (Sweden)

    Xin Gao

    2014-01-01

    Full Text Available The field of teleoperation with force telepresence has expanded its scope to include manipulation at different scales and in virtual worlds, and the key component of which is force feedback hand controller. This paper presents a novel force feedback hand controller system, including a 3-dof translational and 3-dof rotational hand controllers, respectively, to implement position and posture teleoperation of the robot end effector. The 3-dof translational hand controller adopts innovative three-axes decoupling structure based on the linear motor; the 3-dof rotational hand controller adopts serial mechanism based on three-axes intersecting at one point, improving its overall stiffness. Based on the kinematics, statics, and dynamics analyses for two platforms separately, the system applies big closed-loop force control method based on the zero force/torque, improving the feedback force/torque accuracy effectively. Experimental results show that self-developed 6-dof force feedback hand controller has good mechanical properties. The translational hand controller has the following advantages: simple kinematics solver, fast dynamic response, and better than 0.05 mm accuracy of three-axis end positioning, while the advantages of the rotational hand controller are wide turning space, larger than 1 Nm feedback, greater than 180 degrees of operating space of three axes, respectively, and high operation precision.

  12. Magnetic particle separation using controllable magnetic force switches

    International Nuclear Information System (INIS)

    Wei Zunghang; Lee, C.-P.; Lai, M.-F.

    2010-01-01

    Magnetic particle separation is very important in biomedical applications. In this study, a magnetic particle microseparator is proposed that uses micro magnets to produce open/closed magnetic flux for switching on/off the separation. When all magnets are magnetized in the same direction, the magnetic force switch for separation is on; almost all magnetic particles are trapped in the channel side walls and the separation rate can reach 95%. When the magnetization directions of adjacent magnets are opposite, the magnetic force switch for separation is off, and most magnetic particles pass through the microchannel without being trapped. For the separation of multi-sized magnetic particles, the proposed microseparator is numerically demonstrated to have high separation rate.

  13. The climatic out of control. the climatic forcing

    International Nuclear Information System (INIS)

    Bony-Lena, S.; Dufresne, J.L.; Acot, P.; Friedlingstein, P.; Berger, A.; Loutre, M.L.; Raynaud, D.; Thuiller, W.; Le Treut, H.; Houssais, M.N.; Duplessy, J.C.; Royer, J.F.; Douville, H.; Barberousse, A.; Quinon, P.

    2007-01-01

    The expert group on the climate evolution affirms that the global warming is unequivocal and that the human being is the main responsible. This document broaches the climatic change under many aspects: the principle, the historical aspect of the greenhouse effect, the GIEC, the carbon cycle, the paleo-climate theory, the antarctic ices and the impacts of the climatic change on the biodiversity, the simulations and the models, the climatic indicators and the climatic forcing by human activities. (A.L.B.)

  14. The Effect of Isometric Massage on Global Grip Strength after Conservative Treatment of Distal Radial Fractures. Pilot Study.

    Science.gov (United States)

    Ratajczak, Karina; Płomiński, Janusz

    2015-01-01

    The most common fracture of the distal end of the radius is Colles' fracture. Treatment modalities available for use in hand rehabilitation after injury include massage. The aim of this study was to evaluate the effect of isometric massage on the recovery of hand function in patients with Colles fractures. For this purpose, the strength of the finger flexors was assessed as an objective criterion for the evaluation of hand function. The study involved 40 patients, randomly divided into Group A of 20 patients and Group B of 20 patients. All patients received physical therapy and exercised individually with a physiotherapist. Isometric massage was additionally used in Group A. Global grip strength was assessed using a pneumatic force meter on the first and last day of therapy. Statistical analysis was performed using STATISTICA. Statistical significance was defined as a P value of less than 0.05. In both groups, global grip strength increased significantly after the therapy. There was no statistically significant difference between the groups. The men and women in both groups equally improved grip strength. A statistically significant difference was demonstrated between younger and older patients, with younger patients achieving greater gains in global grip strength in both groups. The incorporation of isometric massage in the rehabilitation plan of patients after a distal radial fracture did not significantly contribute to faster recovery of hand function or improve their quality of life.

  15. Design of a smart haptic system for repulsive force control under irregular manipulation environment

    International Nuclear Information System (INIS)

    Lee, Sang-Rock; Choi, Seung-Hyun; Choi, Seung-Bok; Cho, Myeong-Woo

    2014-01-01

    This paper describes how to make an operator feel the desired repulsive force in a haptic system. When an operator manipulates a haptic system, the repulsive force of the operator varies significantly, depending on many factors such as position, velocity and force. In order to reflect the desired repulsive force to the operator, it is commonly known that a haptic system must compensate for irregularly changing forces. The irregularity of the forces, however, has discouraged many researchers from establishing a clear principle on how to make the operator feel the desired repulsive force. To resolve this problem, we introduce a smart haptic framework that can reflect the desired repulsive force to the operator, regardless of the operator’s movement. A dummy governing equation technique is introduced and used to calculate the proper actuating force in real time. The actuating force is generated by a PID controller. To verify the proposed method, a mathematical proof is offered to show that the repulsive force converges to the desired repulsive force. Additionally, to demonstrate the performance of the proposed method, simulational and experimental tests are implemented. (paper)

  16. Position and force control of a vehicle with two or more steerable drive wheels

    Energy Technology Data Exchange (ETDEWEB)

    Reister, D.B.; Unseren, M.A.

    1992-10-01

    When a vehicle with two or more steerable drive wheels is traveling in a circle, the motion of the wheels is constrained. The wheel translational velocity divided by the radius to the center of rotation must be the same for all wheels. When the drive wheels are controlled independently using position control, the motion of the wheels may violate the constraints and the wheels may slip. Consequently, substantial errors can occur in the orientation of the vehicle. A vehicle with N drive wheels has (N - 1) constraints and one degree of freedom. We have developed a new approach to the control of a vehicle with N steerable drive wheels. The novel aspect of our approach is the use of force control. To control the vehicle, we have one degree of freedom for the position on the circle and (N - 1) forces that can be used to reduce errors. Recently, Kankaanranta and Koivo developed a control architecture that allows the force and position degrees of freedom to be decoupled. In the work of Kankaanranta and Koivo the force is an exogenous input. We have made the force endogenous by defining the force in terms of the errors in satisfying the rigid body kinematic constraints. We have applied the control architecture to the HERMIES-III robot and have measured a dramatic reduction in error (more than a factor of 20) compared to motions without force control.

  17. Study on electromagnetism force of CARR control rod drive mechanism experimental machine

    International Nuclear Information System (INIS)

    Zhu Xuewei; Zhen Jianxiao; Wang Yulin; Jia Yueguang; Yang Kun; Yin Haozhe

    2015-01-01

    With the aim of acquiring electromagnetic force and electromagnetic field distributions of control rod drive mechanism (CRDM) in China Advanced Research Reactor (CARR), the force analysis on the CRDM was taken. Manufacturing the experimental machine, the electromagnetic force experiment was taken on it. The electromagnetic field and electromagnetic force simulation analyses of experimental machine were taken, working out distribution data of electromagnetic force and magnetic induction intensity distribution curve, and the effects of permanent magnetic field on electromagnetic field and structure parameters on electromagnetic force. The simulation value is accord with experiment value, the research results provide a reference to electromagnetic force study on CRDM in CARR, and also provide a reference to design of the same type CRDM. (authors)

  18. Adapting haptic guidance authority based on user grip

    NARCIS (Netherlands)

    Smisek, J.; Mugge, W.; Smeets, J.B.J.; Van Paassen, M.M.; Schiele, A

    2014-01-01

    Haptic guidance systems support the operator in task execution using additional forces on the input device. Scaling of the guidance forces determines the control authority of the support system. As task complexity may vary, one level of the guidance scaling may be insufficient, and adaptation of the

  19. Force Control and Nonlinear Master-Slave Force Profile to Manage an Admittance Type Multi-Fingered Haptic User Interface

    Energy Technology Data Exchange (ETDEWEB)

    Anthony L. Crawford

    2012-08-01

    Natural movements and force feedback are important elements in using teleoperated equipment if complex and speedy manipulation tasks are to be accomplished in remote and/or hazardous environments, such as hot cells, glove boxes, decommissioning, explosives disarmament, and space to name a few. In order to achieve this end the research presented in this paper has developed an admittance type exoskeleton like multi-fingered haptic hand user interface that secures the user’s palm and provides 3-dimensional force feedback to the user’s fingertips. Atypical to conventional haptic hand user interfaces that limit themselves to integrating the human hand’s characteristics just into the system’s mechanical design this system also perpetuates that inspiration into the designed user interface’s controller. This is achieved by manifesting the property differences of manipulation and grasping activities as they pertain to the human hand into a nonlinear master-slave force relationship. The results presented in this paper show that the admittance-type system has sufficient bandwidth that it appears nearly transparent to the user when the user is in free motion and when the system is subjected to a manipulation task, increased performance is achieved using the nonlinear force relationship compared to the traditional linear scaling techniques implemented in the vast majority of systems.

  20. Grip Analysis of Road Surface and Tire Footprint Using FEM

    Science.gov (United States)

    Sabri, M.; Abda, S.

    2018-02-01

    Road grip involve a touch between road pavement and the tire tread pattern. The load bearing surface, which depends on pavement roughness and local pressures in the contact patch. This research conducted to develop a Finite element model for simulating the experimentally testing of asphalt in Jl. AH Nasution Medan, North Sumatera Indonesia base on the value of grip coefficient from various tire loads and the various speed of the vehicle during contact to the road. A tire model and road pavement are developed for the analyses the geometry of tire footprint. The results showed that the greater the mass of car will increase grip coefficient. The coefficient of grip on the road surface contact trough the tire footprint strongly influence the kinetic coefficient of friction at certain speeds. Experimentally show that Concrete road grip coefficient of more than 34% compared to the asphalt road at the same IRI parameters (6-8). Kinetic friction coefficient more than 0.33 was obtained in a asphalt path at a speed of 30-40 Km/hour.

  1. A ''Fifth Force'' search using a controlled local mass

    International Nuclear Information System (INIS)

    Nelson, P.; Graham, D.; Nelson, P.; Newman, R.

    1988-01-01

    We present a progress report on a search for composition dependence in the forces acting on lead and copper test masses on a torsion balance due to a copper or lead attracting mass. The attracting mass in this experiment is a ring of radius R positioned so that the torsion balance lies on its axis at a distance z = √3/2.R from the ring's center. The ring is moved periodically between symmetric positions on opposite sides of the balance. The resulting change in gravitational field experienced by the balance is spatially uniform to a very high degree: all derivatives of the change in field at the center of the balance vanish through third order. The problem of gravitational field gradients coupling to the balance is thus minimized. This experiment should provide useful limits on the strength of composition dependent anomalous forces, independent of their range (for ranges greater than about 50 cm), and independent of assumptions about surrounding topography. We describe the performance of a first version of the experiment using a 28 kg copper ring, and discuss plans for an experiment using a 300 kg lead ring. No results are reported

  2. Complimentary Force Allocation Control for a Dual-Mover Linear Switched Reluctance Machine

    Directory of Open Access Journals (Sweden)

    J. F. Pan

    2017-12-01

    Full Text Available This paper inspects the complementary force allocation control schemes for an integrated, dual-mover linear switched reluctance machine (LSRM. The performance of the total force is realized by the coordination of the two movers. First, the structure and characteristics of the LSRM are investigated. Then, a complimentary force allocation control scheme for the two movers is proposed. Next, three force allocation methods—constant proportion, constant proportion with a saturation interval and error compensation, and the variable proportion allocation strategies—are proposed and analyzed, respectively. Experimental results demonstrate that the complimentary force interaction between the two movers can effectively reduce the total amount of force ripples from each method. The results under the variable proportion method also show that dynamic error values falling into 0.044 mm and −0.04 mm under the unit ramp force reference can be achieved. With the sinusoidal force reference with an amplitude of 60 N and a frequency of 0.5 Hz, a dynamic force control precision of 0.062 N and 0.091 N can also be obtained.

  3. Experimental study on the control interaction force coefficient; Soju ryutairyoku kansho keisu ni kansuru jikkenteki kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Nakatake, K; Oda, K; Yoshitake, A; Fujita, K; Nakajima, A [Kyushu University, Fukuoka (Japan). Faculty of Engineering

    1996-04-10

    The interaction force induced to hull by steering is important for prediction of control performance of ships. The control interaction force coefficient dependent on the steering has been investigated through the rudder angle tests using three small model ships with a length of 2.5 m, i.e., mathematical type of ship, cargo type of ship, and tanker type of ship. The interaction forces acting on the hull, propeller, and rudder were determined by measuring the lateral force as well as the forward force of the hydrodynamic forces acting on the rudder. These forces were compared with the theoretically calculated values. Prior to the rudder angle tests, the self propulsion factor and the number of revolution of propeller were determined from the results of the open water tests, resistance tests, and self propulsion tests by the changing load method. The rudder angle tests were conducted under this number of revolution of propeller as a standard condition, and under those increasing and decreasing by 15%. Consequently, the interaction forces determined from the rudder angle tests agreed well with those determined from the other tests. When comparing the control hydrodynamic forces determined from the tests with those theoretically calculated, a similar trend was observed. Effectiveness of the theoretical model was confirmed. 4 refs., 14 figs., 3 tabs.

  4. Simple and Reliable Method to Estimate the Fingertip Static Coefficient of Friction in Precision Grip.

    Science.gov (United States)

    Barrea, Allan; Bulens, David Cordova; Lefevre, Philippe; Thonnard, Jean-Louis

    2016-01-01

    The static coefficient of friction (µ static ) plays an important role in dexterous object manipulation. Minimal normal force (i.e., grip force) needed to avoid dropping an object is determined by the tangential force at the fingertip-object contact and the frictional properties of the skin-object contact. Although frequently assumed to be constant for all levels of normal force (NF, the force normal to the contact), µ static actually varies nonlinearly with NF and increases at low NF levels. No method is currently available to measure the relationship between µ static and NF easily. Therefore, we propose a new method allowing the simple and reliable measurement of the fingertip µ static at different NF levels, as well as an algorithm for determining µ static from measured forces and torques. Our method is based on active, back-and-forth movements of a subject's finger on the surface of a fixed six-axis force and torque sensor. µ static is computed as the ratio of the tangential to the normal force at slip onset. A negative power law captures the relationship between µ static and NF. Our method allows the continuous estimation of µ static as a function of NF during dexterous manipulation, based on the relationship between µ static and NF measured before manipulation.

  5. A methodology for controlling motion and constraint forces in holonomically constrained systems

    International Nuclear Information System (INIS)

    Sapio, Vincent De; Srinivasa, Narayan

    2015-01-01

    Holonomic constraints are ubiquitous in multibody systems. We present an approach to effectively address the control of holonomically constrained systems using a novel decomposition of task, constraint, and posture space. In addition to providing a natural approach for motion control in the presence of constraints, this scheme also allows for concurrent specification of desired constraint forces, given sufficient actuation. It does this by exposing both motion coordinates and constraint forces within the control formalism, allowing for substantial flexibility in control synthesis. Implementations are presented based on a partitioning of the constraint forces into controlled and uncontrolled subsets, as well as a specification of implicit conditions on the constraint forces. A number of examples demonstrate the practical efficacy of the approach. Finally, a system-level methodology for constraint management during robot interactions with the environment is presented

  6. A computed torque method based attitude control with optimal force distribution for articulated body mobile robots

    International Nuclear Information System (INIS)

    Fukushima, Edwardo F.; Hirose, Shigeo

    2000-01-01

    This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)

  7. A methodology for controlling motion and constraint forces in holonomically constrained systems

    Energy Technology Data Exchange (ETDEWEB)

    Sapio, Vincent De, E-mail: vdesapio@hrl.com; Srinivasa, Narayan, E-mail: nsrinivasa@hrl.com [HRL Laboratories, LLC, Information and Systems Sciences Laboratory (United States)

    2015-02-15

    Holonomic constraints are ubiquitous in multibody systems. We present an approach to effectively address the control of holonomically constrained systems using a novel decomposition of task, constraint, and posture space. In addition to providing a natural approach for motion control in the presence of constraints, this scheme also allows for concurrent specification of desired constraint forces, given sufficient actuation. It does this by exposing both motion coordinates and constraint forces within the control formalism, allowing for substantial flexibility in control synthesis. Implementations are presented based on a partitioning of the constraint forces into controlled and uncontrolled subsets, as well as a specification of implicit conditions on the constraint forces. A number of examples demonstrate the practical efficacy of the approach. Finally, a system-level methodology for constraint management during robot interactions with the environment is presented.

  8. Force control of a magnetorheological damper using an elementary hysteresis model-based feedforward neural network

    International Nuclear Information System (INIS)

    Ekkachai, Kittipong; Nilkhamhang, Itthisek; Tungpimolrut, Kanokvate

    2013-01-01

    An inverse controller is proposed for a magnetorheological (MR) damper that consists of a hysteresis model and a voltage controller. The force characteristics of the MR damper caused by excitation signals are represented by a feedforward neural network (FNN) with an elementary hysteresis model (EHM). The voltage controller is constructed using another FNN to calculate a suitable input signal that will allow the MR damper to produce the desired damping force. The performance of the proposed EHM-based FNN controller is experimentally compared to existing control methodologies, such as clipped-optimal control, signum function control, conventional FNN, and recurrent neural network with displacement or velocity inputs. The results show that the proposed controller, which does not require force feedback to implement, provides excellent accuracy, fast response time, and lower energy consumption. (paper)

  9. Identification and Modeling of Electrohydraulic Force Control of the Material Test System (MTS)

    International Nuclear Information System (INIS)

    Ruan, J; Pei, X; Zhu, F M

    2006-01-01

    In the heavy-duty material test device, an electrohydraulic force servo system is usually utilized to load the tested samples. The signal from the pressure sensor is compared with the instruction and the difference between them is then fed to a digital servo valve to form a closed loop control to the target force. The performance of the electrohydraulic force servo system is not only closely related to how accurate to feed the flow rate to the hydraulic cylinder, but also the stiffness of the system which is dominated by the compressibility of oil. Thus the clarification of the characteristic parameters becomes the key of the solution to optimal force control. To identify the electrohydraulic force servo system various step signals are input to excite the dynamic response of the system. From the relationship between the step magnitude and the force response, the system model and the key control parameters are determined. The electrohydraulic force servo system is identified as a first order system with time constant varied with the pressure. Based on the identification of the system optimal control parameters are finally obtained and force rate error is reduced to 0.2% from original 3%

  10. Force control in the absence of visual and tactile feedback

    NARCIS (Netherlands)

    Mugge, W.; Abbink, D.A.; Schouten, Alfred Christiaan; van der Helm, F.C.T.; Arendzen, J.H.; Meskers, C.G.M.

    2013-01-01

    Motor control tasks like stance or object handling require sensory feedback from proprioception, vision and touch. The distinction between tactile and proprioceptive sensors is not frequently made in dynamic motor control tasks, and if so, mostly based on signal latency. We previously found that

  11. Colloquium: Gripped by light: Optical binding

    Czech Academy of Sciences Publication Activity Database

    Dholakia, K.; Zemánek, Pavel

    2010-01-01

    Roč. 82, č. 2 (2010), s. 1767-1791 ISSN 0034-6861 R&D Projects: GA ČR GA202/09/0348; GA MŠk(CZ) LC06007 Institutional research plan: CEZ:AV0Z20650511 Keywords : discrete-dipole approximation * artificial kerr medium * focused laser-beam * near-field optics * radiation pressure * electromagnetic force * trapping force * nonlinear nanosuspensions * spherical nanoparticles * metal nanoparticles Subject RIV: BH - Optics, Masers, Lasers Impact factor: 51.695, year: 2010

  12. Motion Control of Four-Wheel Independently Actuated Electric Ground Vehicles considering Tire Force Saturations

    Directory of Open Access Journals (Sweden)

    Rongrong Wang

    2013-01-01

    Full Text Available A vehicle stability control approach for four-wheel independently actuated (FWIA electric vehicles is presented. The proposed control method consists of a higher-level controller and a lower-level controller. An adaptive control-based higher-level controller is designed to yield the vehicle virtual control efforts to track the desired vehicle motions due to the possible modeling inaccuracies and parametric uncertainties. The lower-level controller considering tire force saturation is given to allocate the required control efforts to the four in-wheel motors for providing the desired tire forces. An analytic method is given to distribute the high-level control efforts, without using the numerical-optimization-based control allocation algorithms. Simulations based on a high-fidelity, CarSim, and full-vehicle model show the effectiveness of the control approach.

  13. Gripping characteristics of an electromagnetically activated magnetorheological fluid-based gripper

    Science.gov (United States)

    Choi, Young T.; Hartzell, Christine M.; Leps, Thomas; Wereley, Norman M.

    2018-05-01

    The design and test of a magnetorheological fluid (MRF)-based universal gripper (MR gripper) are presented in this study. The MR gripper was developed to have a simple design, but with the ability to produce reliable gripping and handling of a wide range of simple objects. The MR gripper design consists of a bladder mounted atop an electromagnet, where the bladder is filled with an MRF, which was formulated to have long-term stable sedimentation stability, that was synthesized using a high viscosity linear polysiloxane (HVLP) carrier fluid with a carbonyl iron particle (CIP) volume fraction of 35%. Two bladders were fabricated: a magnetizable bladder using a magnetorheological elastomer (MRE), and a passive (non-magnetizable) silicone rubber bladder. The holding force and applied (initial compression) force of the MR gripper for a bladder fill volume of 75% were experimentally measured, for both magnetizable and passive bladders, using a servohydraulic material testing machine for a range of objects. The gripping performance of the MR gripper using an MRE bladder was compared to that of the MR gripper using a passive bladder.

  14. Dynamical signatures of isometric force control as a function of age, expertise, and task constraints.

    Science.gov (United States)

    Vieluf, Solveig; Sleimen-Malkoun, Rita; Voelcker-Rehage, Claudia; Jirsa, Viktor; Reuter, Eva-Maria; Godde, Ben; Temprado, Jean-Jacques; Huys, Raoul

    2017-07-01

    From the conceptual and methodological framework of the dynamical systems approach, force control results from complex interactions of various subsystems yielding observable behavioral fluctuations, which comprise both deterministic (predictable) and stochastic (noise-like) dynamical components. Here, we investigated these components contributing to the observed variability in force control in groups of participants differing in age and expertise level. To this aim, young (18-25 yr) as well as late middle-aged (55-65 yr) novices and experts (precision mechanics) performed a force maintenance and a force modulation task. Results showed that whereas the amplitude of force variability did not differ across groups in the maintenance tasks, in the modulation task it was higher for late middle-aged novices than for experts and higher for both these groups than for young participants. Within both tasks and for all groups, stochastic fluctuations were lowest where the deterministic influence was smallest. However, although all groups showed similar dynamics underlying force control in the maintenance task, a group effect was found for deterministic and stochastic fluctuations in the modulation task. The latter findings imply that both components were involved in the observed group differences in the variability of force fluctuations in the modulation task. These findings suggest that between groups the general characteristics of the dynamics do not differ in either task and that force control is more affected by age than by expertise. However, expertise seems to counteract some of the age effects. NEW & NOTEWORTHY Stochastic and deterministic dynamical components contribute to force production. Dynamical signatures differ between force maintenance and cyclic force modulation tasks but hardly between age and expertise groups. Differences in both stochastic and deterministic components are associated with group differences in behavioral variability, and observed behavioral

  15. Prediction of forces and moments for flight vehicle control effectors. Part 1: Validation of methods for predicting hypersonic vehicle controls forces and moments

    Science.gov (United States)

    Maughmer, Mark D.; Ozoroski, L.; Ozoroski, T.; Straussfogel, D.

    1990-01-01

    Many types of hypersonic aircraft configurations are currently being studied for feasibility of future development. Since the control of the hypersonic configurations throughout the speed range has a major impact on acceptable designs, it must be considered in the conceptual design stage. The ability of the aerodynamic analysis methods contained in an industry standard conceptual design system, APAS II, to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds is considered. Predicted control forces and moments generated by various control effectors are compared with previously published wind tunnel and flight test data for three configurations: the North American X-15, the Space Shuttle Orbiter, and a hypersonic research airplane concept. Qualitative summaries of the results are given for each longitudinal force and moment and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage. Results for most lateral/directional control derivatives are acceptable for conceptual design purposes; however, predictions at supersonic Mach numbers for the change in yawing moment due to aileron deflection and the change in rolling moment due to rudder deflection are found to be unacceptable. Including shielding effects in the analysis is shown to have little effect on lift and pitching moment predictions while improving drag predictions.

  16. Hybrid Force Control Based on ICMAC for an Astronaut Rehabilitative Training Robot

    Directory of Open Access Journals (Sweden)

    Lixun Zhang

    2012-08-01

    Full Text Available A novel Astronaut Rehabilitative Training Robot (ART based on a cable-driven mechanism is represented in this paper. ART, a typical passive force servo system, can help astronauts to bench press in a microgravity environment. The purpose of this paper is to design controllers to eliminate the surplus force caused by an astronaut's active movements. Based on the dynamics modelling of the cable-driven unit, a hybrid force controller based on improved credit assignment CMAC (ICMAC is presented. A planning method for the cable tension is proposed so that the dynamic load produced by the ART can realistically simulate the gravity and inertial force of the barbell in a gravity environment. Finally, MATLAB simulation results of the man-machine cooperation system are provided in order to verify the effectiveness of the proposed control strategy. The simulation results show that the hybrid control method based on the structure invariance principle can inhibit the surplus force and that ICMAC can improve the dynamic performance of the passive force servo system. Furthermore, the hybrid force controller based on ICMAC can ensure the stability of the system.

  17. Reform of Command and Control Structures in North Atlantic Treaty Organization Special Operations Forces

    National Research Council Canada - National Science Library

    Berg, Robert S

    2007-01-01

    .... The central research question is as follows: Does NATO require a standing Special Operations Force Command and Control structure and combat capability to meet the emerging global security requirements of the Alliance...

  18. Centralized Command and Control of Theater Missile Defense: The Joint Force Missile Defense Component Coordinator

    National Research Council Canada - National Science Library

    Bucey, William H

    2006-01-01

    .... The numerous commands, decentralized command and control, and limited and expensive resources involved in TMD require changes to the joint doctrine in order to provide unity of command and economy of force...

  19. Sliding mode-based lateral vehicle dynamics control using tyre force measurements

    Science.gov (United States)

    Kunnappillil Madhusudhanan, Anil; Corno, Matteo; Holweg, Edward

    2015-11-01

    In this work, a lateral vehicle dynamics control based on tyre force measurements is proposed. Most of the lateral vehicle dynamics control schemes are based on yaw rate whereas tyre forces are the most important variables in vehicle dynamics as tyres are the only contact points between the vehicle and road. In the proposed method, active front steering is employed to uniformly distribute the required lateral force among the front left and right tyres. The force distribution is quantified through the tyre utilisation coefficients. In order to address the nonlinearities and uncertainties of the vehicle model, a gain scheduling sliding-mode control technique is used. In addition to stabilising the lateral dynamics, the proposed controller is able to maintain maximum lateral acceleration. The proposed method is tested and validated on a multi-body vehicle simulator.

  20. Vehicle Sliding Mode Control with Adaptive Upper Bounds: Static versus Dynamic Allocation to Saturated Tire Forces

    Directory of Open Access Journals (Sweden)

    Ali Tavasoli

    2012-01-01

    Full Text Available Nonlinear vehicle control allocation is achieved through distributing the task of vehicle control among individual tire forces, which are constrained to nonlinear saturation conditions. A high-level sliding mode control with adaptive upper bounds is considered to assess the body yaw moment and lateral force for the vehicle motion. The proposed controller only requires the online adaptation of control gains without acquiring the knowledge of upper bounds on system uncertainties. Static and dynamic control allocation approaches have been formulated to distribute high-level control objectives among the system inputs. For static control allocation, the interior-point method is applied to solve the formulated nonlinear optimization problem. Based on the dynamic control allocation method, a dynamic update law is derived to allocate vehicle control to tire forces. The allocated tire forces are fed into a low-level control module, where the applied torque and active steering angle at each wheel are determined through a slip-ratio controller and an inverse tire model. Computer simulations are used to prove the significant effects of the proposed control allocation methods on improving the stability and handling performance. The advantages and limitations of each method have been discussed, and conclusions have been derived.

  1. Consequences of Inconsistency in Air Force Tobacco Control Policy.

    Science.gov (United States)

    Lando-King, Elizabeth A; Malone, Ruth E; Haddock, Christopher K; Poston, Walker S Carlos; Lando, Harry A; Jahnke, Sara A; Hawk, Nita; Smith, Elizabeth A

    2017-04-01

    Although the United States Air Force (USAF) has been a leader in efforts to reduce tobacco use among service members, tobacco continues to be a problem and initiatives to decrease tobacco use further require buy-in from leadership. We explored line leaderships' perspectives on tobacco. A diverse group of 10 senior commissioned and 10 non-commissioned personnel were interviewed. Respondents reported substantial changes in the culture of tobacco use during their years of service, from near ubiquity to restricted use areas. They also perceived mixed messages coming from the USAF, including simultaneous discouragement of and accommodations for tobacco use, and variability in policies and enforcement. Many respondents indicated that allowing tobacco use creates conflict and undermines military discipline and suggested that a tobacco-free policy would be the best way to eliminate these contradictions. Although there has been substantial movement away from a culture of tobacco in the USAF, current policies and variable enforcement of these policies create unnecessary contradictions. Establishing a tobacco-free service would resolve these issues in addition to improving the health of service members and veterans.

  2. A COMPARATIVE STUDY TO FIND OUT IMMEDIATE EFFECTIVENESS OF MOVEMENT WITH MOBILIZATION VERSUS ELBOW ORTHOSIS ON PAIN AND GRIP STRENGTH IN LATERAL EPICONDYLITIS IN HOUSEWIVES

    Directory of Open Access Journals (Sweden)

    Trishna Kakati

    2015-12-01

    both Mulligan’s MWM technique and counter force elbow orthosis produces significant decrease in pain and improvement in grip strength immediately after treatment. It has been seen that Mulligan’s MWM is better than counter force elbow orthosis in relieving pain (p=0.03. Increase in hand grip strength does not differ remarkably in both treatment groups.

  3. Vehicle Dynamics Control of In-wheel Electric Motor Drive Vehicles Based on Averaging of Tire Force Usage

    Science.gov (United States)

    Masaki, Nobuo; Iwano, Haruo; Kamada, Takayoshi; Nagai, Masao

    For in-wheel electric motor drive vehicles, a new vehicle dynamics control which is based on the tire force usage rate is proposed. The new controller adopts non-linear optimal control could manage the interference between direct yaw-moment control and the tire force usage rate. The new control is considered total longitudinal and transverse tire force. Therefore the controller can prevent tire force saturation near tire force limit during cornering. Simulations and test runs by the custom made four wheel drive in-wheel motor electric vehicle show that higher driving stability performance compared to the performance of the same vehicle without control.

  4. Composite adaptive control of belt polishing force for aero-engine blade

    Science.gov (United States)

    Zhsao, Pengbing; Shi, Yaoyao

    2013-09-01

    The existing methods for blade polishing mainly focus on robot polishing and manual grinding. Due to the difficulty in high-precision control of the polishing force, the blade surface precision is very low in robot polishing, in particular, quality of the inlet and exhaust edges can not satisfy the processing requirements. Manual grinding has low efficiency, high labor intensity and unstable processing quality, moreover, the polished surface is vulnerable to burn, and the surface precision and integrity are difficult to ensure. In order to further improve the profile accuracy and surface quality, a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed, which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together. By the mode decision-making mechanism, Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value, and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision. Based on the mathematical model of the force-exerting mechanism, simulation analysis is implemented on DSCAC. Simulation results show that the output polishing force can better track the given signal. Finally, the blade polishing experiments are carried out on the designed polishing equipment. Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility, valve dead-time effect, valve nonlinear flow, cylinder friction, measurement noise and other interference on the control precision of polishing force, which has high control precision, strong robustness, strong anti-interference ability and other advantages compared with MRACFNN. The proposed research achieves high-precision control of the polishing force, effectively improves the blade machining precision and surface consistency, and

  5. Combining spanwise morphing, inline motion and model based optimization for force magnitude and direction control

    Science.gov (United States)

    Scheller, Johannes; Braza, Marianna; Triantafyllou, Michael

    2016-11-01

    Bats and other animals rapidly change their wingspan in order to control the aerodynamic forces. A NACA0013 type airfoil with dynamically changing span is proposed as a simple model to experimentally study these biomimetic morphing wings. Combining this large-scale morphing with inline motion allows to control both force magnitude and direction. Force measurements are conducted in order to analyze the impact of the 4 degree of freedom flapping motion on the flow. A blade-element theory augmented unsteady aerodynamic model is then used to derive optimal flapping trajectories.

  6. Dicyclopentadiene Hydrogenation in Trickle Bed Reactor under Forced Periodic Control

    Czech Academy of Sciences Publication Activity Database

    Skála, D.; Hanika, Jiří

    2008-01-01

    Roč. 62, č. 2 (2008), s. 215-218 ISSN 1336-7242 R&D Projects: GA MPO(CZ) FT-TA/039 Institutional research plan: CEZ:AV0Z40720504 Keywords : periodic control * trickle -bed reactor * dicyclopentadiene Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  7. Tyre-road grip coefficient assessment - Part II: online estimation using instrumented vehicle, extended Kalman filter, and neural network

    Science.gov (United States)

    Luque, Pablo; Mántaras, Daniel A.; Fidalgo, Eloy; Álvarez, Javier; Riva, Paolo; Girón, Pablo; Compadre, Diego; Ferran, Jordi

    2013-12-01

    The main objective of this work is to determine the limit of safe driving conditions by identifying the maximal friction coefficient in a real vehicle. The study will focus on finding a method to determine this limit before reaching the skid, which is valuable information in the context of traffic safety. Since it is not possible to measure the friction coefficient directly, it will be estimated using the appropriate tools in order to get the most accurate information. A real vehicle is instrumented to collect information of general kinematics and steering tie-rod forces. A real-time algorithm is developed to estimate forces and aligning torque in the tyres using an extended Kalman filter and neural networks techniques. The methodology is based on determining the aligning torque; this variable allows evaluation of the behaviour of the tyre. It transmits interesting information from the tyre-road contact and can be used to predict the maximal tyre grip and safety margin. The maximal grip coefficient is estimated according to a knowledge base, extracted from computer simulation of a high detailed three-dimensional model, using Adams® software. The proposed methodology is validated and applied to real driving conditions, in which maximal grip and safety margin are properly estimated.

  8. The Effects of Counterforce Brace Size on the Wrist Range of Motility, Pain, Grip & Wrist Extension Sterngth in Normal Subjects and Patients with Tennis Elbow

    Directory of Open Access Journals (Sweden)

    Ali Asghar Jameh-Bozorgi

    2006-04-01

    Full Text Available Objective: Counter force brace is one of the most usefull treatments for lateral opicondylitis (Tennis elbow because it decreases grip pain and increases the power of grip, power of wrist extension and Wrist Range of Motility. The purpose of this quasi experimental (repeated measurementsstudy was to determine the effect of 3 counterforce brace sizes on the wrist R.O.M, grip and wrist extension strength and pain intensity in two groups of healthy subjects and patients with tennis elbow. Materials & Methods: 18 normal subjects & 18 patients with tennis elbow were selected simple conveniently and were tested with no brace and 3 size of counterforce (1,2 and 3 inches. The R.O.M , strength and pain intensity were measured by jamar goniometry and Nicholas MMT dynamometry & VAS, respectively. Results: 1 With all sizes there was a significant decrease of R.O.M on normal subjects but no significant difference in patients. 2 There was a significant decrease of grip strength with 1-inch brace in normal subjects but a significant increase of grip strength with 2 and 3-inch brace in patiens. 3 All sizes of brace caused significant decrease of extension strength in normal subjects but increase in patients. 4All size caused significant decrease of pain intensity that was more considerable in the case of 2 and 3 inch size. Conclusion: The results shows that the counterforce brace may be considered as an effective treatment for increasing strength and decreasing pain in patients with tennis elbow.

  9. Using the modern CNC controllers capabilities for estimating the machining forces during the milling process

    Directory of Open Access Journals (Sweden)

    Breaz Radu-Eugen

    2017-01-01

    Full Text Available Machining forces can nowadays be measured by using 3D dynamometers, which are usually very expensive devices and hardly available for most of the CNC machine-tools users. On the other hand, modern CNC controllers have nowadays the ability to display and save many outputs within the machining process, such as the currents or even the torques at the shaft's level for the feed motors on each axis. These outputs can be used for estimating the machining forces, but it is to be noticed that the above-mentioned currents and torques are proportional with the overall resistant forces, which includes not only technological forces, but also friction, inertial and pre-tensioning forces. This paper presents an approach for estimating the machining forces during a milling process, by using the outputs stored in the CNC controller and separating the effects of technological forces from the other forces involved in the process. The separation was made by running two sets of experiments, one set for dry-run regime and the other one for machining regime.

  10. Robust Operation of Tendon-Driven Robot Fingers Using Force and Position-Based Control Laws

    Science.gov (United States)

    Abdallah, Muhammad E (Inventor); Platt, Jr., Robert J. (Inventor); Reiland, Matthew J (Inventor); Hargrave, Brian (Inventor); Diftler, Myron A (Inventor); Strawser, Philip A (Inventor); Ihrke, Chris A. (Inventor)

    2013-01-01

    A robotic system includes a tendon-driven finger and a control system. The system controls the finger via a force-based control law when a tension sensor is available, and via a position-based control law when a sensor is not available. Multiple tendons may each have a corresponding sensor. The system selectively injects a compliance value into the position-based control law when only some sensors are available. A control system includes a host machine and a non-transitory computer-readable medium having a control process, which is executed by the host machine to control the finger via the force- or position-based control law. A method for controlling the finger includes determining the availability of a tension sensor(s), and selectively controlling the finger, using the control system, via the force or position-based control law. The position control law allows the control system to resist disturbances while nominally maintaining the initial state of internal tendon tensions.

  11. Ground reaction force comparison of controlled resistance methods to isoinertial loading of the squat exercise - biomed 2010.

    Science.gov (United States)

    Paulus, David C; Reynolds, Michael C; Schilling, Brian K

    2010-01-01

    The ground reaction force during the concentric (raising) portion of the squat exercise was compared to that of isoinertial loading (free weights) for three pneumatically controlled resistance methods: constant resistance, cam force profile, and proportional force control based on velocity. Constant force control showed lower ground reaction forces than isoinertial loading throughout the range of motion (ROM). The cam force profile exhibited slightly greater ground reaction forces than isoinertial loading at 10 and 40% ROM with fifty-percent greater loading at 70% ROM. The proportional force control consistently elicited greater ground reaction force than isoinertial loading, which progressively ranged from twenty to forty percent increase over isoinertial loading except for being approximately equal at 85% ROM. Based on these preliminary results, the proportional control shows the most promise for providing loading that is comparable in magnitude to isoinertial loading. This technology could optimize resistance exercise for sport-specific training or as a countermeasure to atrophy during spaceflight.

  12. Estimation of excitation forces for wave energy converters control using pressure measurements

    Science.gov (United States)

    Abdelkhalik, O.; Zou, S.; Robinett, R.; Bacelli, G.; Wilson, D.

    2017-08-01

    Most control algorithms of wave energy converters require prediction of wave elevation or excitation force for a short future horizon, to compute the control in an optimal sense. This paper presents an approach that requires the estimation of the excitation force and its derivatives at present time with no need for prediction. An extended Kalman filter is implemented to estimate the excitation force. The measurements in this approach are selected to be the pressures at discrete points on the buoy surface, in addition to the buoy heave position. The pressures on the buoy surface are more directly related to the excitation force on the buoy as opposed to wave elevation in front of the buoy. These pressure measurements are also more accurate and easier to obtain. A singular arc control is implemented to compute the steady-state control using the estimated excitation force. The estimated excitation force is expressed in the Laplace domain and substituted in the control, before the latter is transformed to the time domain. Numerical simulations are presented for a Bretschneider wave case study.

  13. Gripped by movies: From story-world to artifact absorption

    NARCIS (Netherlands)

    Doicaru, M.M.

    2016-01-01

    That movies are a great source of entertainment seems to be common sense. But how exactly movies manage to get large audiences absorbed, or what is their gripping tool is still a mystery. Research makes use of different concepts pointing to narrative absorption, but it is not clear how they differ

  14. Hand Grip Strength Vs. Sprint Effectiveness in Amputee Soccer Players.

    Science.gov (United States)

    Wieczorek, Marta; Wiliński, Wojciech; Struzik, Artur; Rokita, Andrzej

    2015-11-22

    Amputee soccer is one of the types of soccer designed for the disabled, especially those who have undergone amputations, as well as those with extremity dysfunction. The objective of the study was to find the relationship between hand grip strength and sprint time in amputee soccer players. Thirteen field amputee soccer players participated in the study. A SAEHAN hydraulic hand dynamometer manufactured by Jamar was used for hand grip strength measurements. The sprint running test was conducted over a distance of 30 m. The Fusion Smart Speed System was employed for running time measurements. No statistically significant relationships were found between hand grip strength of the left or right hand, and sprint times over 1, 5, 10, 15, 20, 25 and 30 m. Analysis of the running velocity curve of the subjects showed an interesting profile characterized by a 15 meter-long acceleration phase and a significant velocity increase over a distance of 20 - 25 m. The study suggests that there is no relationship between hand grip strength and sprint effectiveness in amputee soccer players. The specificity of locomotion with the use of elbow crutches among elite Polish amputee soccer players probably accounts for the profile of the sprint velocity curve. Extension of the acceleration phase in the sprint run and a velocity increase in the subsequent part of the run were observed.

  15. Hand Grip Strength Vs. Sprint Effectiveness in Amputee Soccer Players

    Directory of Open Access Journals (Sweden)

    Wieczorek Marta

    2015-12-01

    Full Text Available Amputee soccer is one of the types of soccer designed for the disabled, especially those who have undergone amputations, as well as those with extremity dysfunction. The objective of the study was to find the relationship between hand grip strength and sprint time in amputee soccer players. Thirteen field amputee soccer players participated in the study. A SAEHAN hydraulic hand dynamometer manufactured by Jamar was used for hand grip strength measurements. The sprint running test was conducted over a distance of 30 m. The Fusion Smart Speed System was employed for running time measurements. No statistically significant relationships were found between hand grip strength of the left or right hand, and sprint times over 1, 5, 10, 15, 20, 25 and 30 m. Analysis of the running velocity curve of the subjects showed an interesting profile characterized by a 15 meter-long acceleration phase and a significant velocity increase over a distance of 20 – 25 m. The study suggests that there is no relationship between hand grip strength and sprint effectiveness in amputee soccer players. The specificity of locomotion with the use of elbow crutches among elite Polish amputee soccer players probably accounts for the profile of the sprint velocity curve. Extension of the acceleration phase in the sprint run and a velocity increase in the subsequent part of the run were observed.

  16. Grip and Pinch Strength Norms for Michigan Workers

    Directory of Open Access Journals (Sweden)

    Joel M. Phillips M.S., OTRL

    2013-06-01

    Full Text Available The purpose of this study was to create a norm reference of current grip and pinch strength norms for working-age Michigan adults. This normative study included a convenience sample of 179 volunteers who were employees at car plants in South East Michigan or hospital sites in West Michigan. Participants’ ages ranged from between 20 and 62 years of age with a mean age of 49.15 years. There were 78 females (44% and 101 males (56%. Subjects were classified by gender and in the age categories of ages 20 to 49 years and ages 50-62 years. Grip and pinch strength norms were collected following the American Society of Hand Therapy protocol. The norms from these working adults were calculated with descriptive statistics for males and females in two age classifications: ages 20 to 49 and ages 50 to 62 years. Standard Errors (SE are better than the 1985 norms for both males and females ages 20 to 49 years. SEs are higher than the ages 20 to 49 years’ norms for the ages 50 to 62 years age categories in both males and females. These norms offer a point of comparison for clinicians to use for clients in Michigan who are ages 20 to 62 years and who have a goal to improve their grip strength. Clients’ grip and pinch strength could be compared to their age level or gender norms using the comparison for one standard deviation above, below, or at the means.

  17. Wearable flex sensor system for multiple badminton player grip identification

    Science.gov (United States)

    Jacob, Alvin; Zakaria, Wan Nurshazwani Wan; Tomari, Mohd Razali Bin Md; Sek, Tee Kian; Suberi, Anis Azwani Muhd

    2017-09-01

    This paper focuses on the development of a wearable sensor system to identify the different types of badminton grip that is used by a player during training. Badminton movements and strokes are fast and dynamic, where most of the involved movement are difficult to identify with the naked eye. Also, the usage of high processing optometric motion capture system is expensive and causes computational burden. Therefore, this paper suggests the development of a sensorized glove using flex sensor to measure a badminton player's finger flexion angle. The proposed Hand Monitoring Module (HMM) is connected to a personal computer through Bluetooth to enable wireless data transmission. The usability and feasibility of the HMM to identify different grip types were examined through a series of experiments, where the system exhibited 70% detection ability for the five different grip type. The outcome plays a major role in training players to use the proper grips for a badminton stroke to achieve a more powerful and accurate stroke execution.

  18. Design of a new adaptive fuzzy controller and its implementation for the damping force control of a magnetorheological damper

    International Nuclear Information System (INIS)

    Phu, Do Xuan; Shah, Kruti; Choi, Seung-Bok

    2014-01-01

    This paper presents a new adaptive fuzzy controller and its implementation for the damping force control of a magnetorheological (MR) fluid damper in order to validate the effectiveness of the control performance. An interval type 2 fuzzy model is built, and then combined with modified adaptive control to achieve the desired damping force. In the formulation of the new adaptive controller, an enhanced iterative algorithm is integrated with the fuzzy model to decrease the time of calculation (D Wu 2013 IEEE Trans. Fuzzy Syst. 21 80–99) and the control algorithm is synthesized based on the H ∞ tracking technique. In addition, for the verification of good control performance of the proposed controller, a cylindrical MR damper which can be applied to the vibration control of a washing machine is designed and manufactured. For the operating fluid, a recently developed plate-like particle-based MR fluid is used instead of a conventional MR fluid featuring spherical particles. To highlight the control performance of the proposed controller, two existing adaptive fuzzy control algorithms proposed by other researchers are adopted and altered for a comparative study. It is demonstrated from both simulation and experiment that the proposed new adaptive controller shows better performance of damping force control in terms of response time and tracking accuracy than the existing approaches. (papers)

  19. Design of Robust AMB Controllers for Rotors Subjected to Varying and Uncertain Seal Forces

    DEFF Research Database (Denmark)

    Lauridsen, Jonas Skjødt; Santos, Ilmar

    2017-01-01

    This paper demonstrates the design and simulation results of model based controllers for AMB systems, subjectedto uncertain and changing dynamic seal forces. Specifically, a turbocharger with a hole-pattern seal mounted acrossthe balance piston is considered. The dynamic forces of the seal, which...... are dependent on the operational conditions,have a significant effect on the overall system dynamics. Furthermore, these forces are considered uncertain.The nominal and the uncertainty representation of the seal model are established using results from conventionalmodelling approaches, i.e. CFD and Bulkflow......, and experimental results. Three controllers are synthesized: I) AnH∞ controller based on nominal plant representation, II) A µ controller, designed to be robust against uncertaintiesin the dynamic seal model and III) a Linear Parameter Varying (LPV) controller, designed to provide a unifiedperformance over a large...

  20. Validation of engineering methods for predicting hypersonic vehicle controls forces and moments

    Science.gov (United States)

    Maughmer, M.; Straussfogel, D.; Long, L.; Ozoroski, L.

    1991-01-01

    This work examines the ability of the aerodynamic analysis methods contained in an industry standard conceptual design code, the Aerodynamic Preliminary Analysis System (APAS II), to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds. Predicted control forces and moments generated by various control effectors are compared with previously published wind-tunnel and flight-test data for three vehicles: the North American X-15, a hypersonic research airplane concept, and the Space Shuttle Orbiter. Qualitative summaries of the results are given for each force and moment coefficient and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage.

  1. Grip strength as a frailty diagnostic component in geriatric inpatients

    Directory of Open Access Journals (Sweden)

    Dudzińska-Griszek J

    2017-07-01

    Full Text Available Joanna Dudzińska-Griszek, Karolina Szuster, Jan Szewieczek Department of Geriatrics, School of Health Sciences in Katowice, Medical University of Silesia, Katowice, Poland Background: Frailty has emerged as a key medical syndrome predictive of comorbidity, disability, institutionalization and death. As a component of the five frailty phenotype diagnostic criteria, patient grip strength deserves attention as a simple and objective measure of the frailty syndrome. The aim of this study was to assess conditions that influence grip strength in geriatric inpatients.Patients and methods: The study group consisted of 80 patients aged 78.6±7.0 years ( X ± SD, with 68.8% women, admitted to the Department of Geriatrics. A comprehensive geriatric assessment was complemented with assessment for the frailty phenotype as described by Fried et al for all patients in the study group. Functional assessment included Barthel Index of Activities of Daily Living (Barthel Index, Instrumental Activities of Daily Living Scale and Mini-Mental State Examination.Results: Three or more frailty criteria were positive in 32 patients (40%, while 56 subjects (70% fulfilled the frailty criterion of weakness (grip strength test. Multivariate linear regression analysis revealed that two independent measures showed positive association with grip strength – Mini-Mental State Examination score (β=0.239; P=0.001 and statin use (β=0.213; P=0.002 – and four independent measures were negatively associated with grip strength – female sex (β=–0.671; P<0.001, C-reactive protein (β=–0.253; P<0.001, prior myocardial infarction (β=–0.190; P=0.006 and use of an antidepressant (β=–0.163; P=0.018. Low physical activity was identified as the only independent qualitative frailty component associated with 2-year mortality in multivariate logistic regression analysis after adjustment for age and sex (odds ratio =6.000; 95% CI =1.357–26.536; P=0.018.Conclusion: Cognitive

  2. Automated boundary interaction force control of micromanipulators with in situ applications to microsurgery

    International Nuclear Information System (INIS)

    Eslami, Sohrab; Jalili, Nader

    2012-01-01

    Most recent works on miniature tasks are concentrated on developing tools to take advantage of the visual servoing feedback to control the ultra-small interaction forces. This paper spans an extensive platform for automatic controlling of boundary interaction forces with high precision in the level of micro/nano-Newton with extensive micro/nanoengineering applications such as the microsurgery. To this end, a comprehensive piezoresistive microcantilever (PMC) model considering the shear deformation and rotary inertia effects treating as the distributed-parameters model along with the Hertzian contact force is presented. The purpose of considering the Hertzian contact force model is to investigate the dynamic response of the interaction force between the microcantilever's tip and the specimen. Afterward, a control platform is introduced to automatically manipulate the PMC to follow an ideal micro/nano-interaction force. By using the integrated PMC with the micromanipulator and a digital signal processor, an intuitive programming code is written to incorporate the micromanipulator and the controller in a real-time framework. To calibrate and verify the induced voltage in the PMC, a self-sensing experiment on the piezoelectric microcantilever is carried out to warrant the calibration procedure. Some experiments are established to affirm the validity of the proposed control for the autonomous real-time tasks on the boundary interaction force control. Unlike the conventional research studies, the measured force here contributes as the feedback source in contrast to the vision feedback while force sensors possess more precision, productivity and small size. This technique has several potential applications listed but not limited to the micro/nanomanipulation, developing artificial biological systems (e.g., fabricating hydrogel for the scaffold), and medicine such as microsurgery. As a result, using the proposed platform, we are able to manipulate and control the

  3. Biological forcing controls the chemistry of the coral exoskeleton

    Science.gov (United States)

    Meibom, A.; Mostefaoui, S.; Cuif, J.; Yurimoto, H.; Dauphin, Y.; Houlbreque, F.; Dunbar, R.; Constantz, B.

    2006-12-01

    A multitude of marine organisms produce calcium carbonate skeletons that are used extensively to reconstruct water temperature variability of the tropical and subtropical oceans - a key parameter in global climate-change models. Such paleo-climate reconstructions are based on the notion that skeletal oxygen isotopic composition and certain trace-element abundances (e.g., Sr/Ca and Mg/Ca ratios) vary in response to changes in the water temperature. However, it is a fundamental problem that poorly understood biological processes introduce large compositional deviations from thermodynamic equilibrium and hinder precise calibrations of many paleo-climate proxies. Indeed, the role of water temperature in controlling the composition of the skeleton is far from understood. We have studied trace-element abundances as well as oxygen and carbon isotopic compositions of individual skeletal components in the zooxanthellate and non-zooxanthellate corals at ultra-structural, i.e. micrometer to sub-micrometer length scales. From this body of work we draw the following, generalized conclusions: 1) Centers of calcification (COC) are not in equilibrium with seawater. Notably, the Sr/Ca ratio is higher than expected for aragonite equilibrium with seawater at the temperature at which the skeleton was formed. Furthermore, the COC are further away from equilibrium with seawater than fibrous skeleton in terms of stable isotope composition. 2) COC are dramatically different from the fibrous aragonite skeleton in terms of trace element composition. 3) Neither trace element nor stable isotope variations in the fibrous (bulk) part of the skeleton are directly related to changes in SST. In fact, changes in SST can have very little to do with the observed compositional variations. 4) Trace element variations in the fibrous (bulk) part of the skeleton are not related to the activity of zooxanthellae. These observations are directly relevant to the issue of biological versus non

  4. End-Point Contact Force Control with Quantitative Feedback Theory for Mobile Robots

    Directory of Open Access Journals (Sweden)

    Shuhuan Wen

    2012-12-01

    Full Text Available Robot force control is an important issue for intelligent mobile robotics. The end-point stiffness of a robot is a key and open problem in the research community. The control strategies are mostly dependent on both the specifications of the task and the environment of the robot. Due to the limited stiffness of the end-effector, we may adopt inherent torque to feedback the oscillations of the controlled force. This paper proposes an effective control strategy which contains a controller using quantitative feedback theory. The nested loop controllers take into account the physical limitation of the system's inner variables and harmful interference. The biggest advantage of the method is its simplicity in both the design process and the implementation of the control algorithm in engineering practice. Taking the one-link manipulator as an example, numerical experiments are carried out to verify the proposed control method. The results show the satisfactory performance.

  5. Interaction force and motion estimators facilitating impedance control of the upper limb rehabilitation robot.

    Science.gov (United States)

    Mancisidor, Aitziber; Zubizarreta, Asier; Cabanes, Itziar; Bengoa, Pablo; Jung, Je Hyung

    2017-07-01

    In order to enhance the performance of rehabilitation robots, it is imperative to know both force and motion caused by the interaction between user and robot. However, common direct measurement of both signals through force and motion sensors not only increases the complexity of the system but also impedes affordability of the system. As an alternative of the direct measurement, in this work, we present new force and motion estimators for the proper control of the upper-limb rehabilitation Universal Haptic Pantograph (UHP) robot. The estimators are based on the kinematic and dynamic model of the UHP and the use of signals measured by means of common low-cost sensors. In order to demonstrate the effectiveness of the estimators, several experimental tests were carried out. The force and impedance control of the UHP was implemented first by directly measuring the interaction force using accurate extra sensors and the robot performance was compared to the case where the proposed estimators replace the direct measured values. The experimental results reveal that the controller based on the estimators has similar performance to that using direct measurement (less than 1 N difference in root mean square error between two cases), indicating that the proposed force and motion estimators can facilitate implementation of interactive controller for the UHP in robotmediated rehabilitation trainings.

  6. Development of master slave system for interventional radiology with force-rate control

    International Nuclear Information System (INIS)

    Ide, Masaru; Zobel, P.B.; Claudio, P.D.; Mohri, Makoto; Komeda, Takashi

    2010-01-01

    The objective of this study is to develop a master-slave system for a catheter-guided operation, which is performed by using radiology, through the vascular system. When the master-slave system is used, the surgeon is not exposed to x-rays during the operation. The master tool is managed by an operator away from the slave tool, which is near the patient. The system must provide a realistic picture to the surgeon, particularly in term of force information because this operation is performed by observing three-dimensional fields on a two-dimensional monitor. In this paper, we describe the development of a master slave system that involves the use of force-rate control for guiding the catheter without using force sensors. The master tool has a force-display function. This system can be controlled by force and velocity controlling; hence, this system realized an innovative mechanism and algorism. Finally, the preliminary experiment indicated that the new control method was effective. Further, the force display was stable and achieved fast response. (author)

  7. iCub Whole-body Control through Force Regulation on Rigid Noncoplanar Contacts

    Directory of Open Access Journals (Sweden)

    Francesco eNori

    2015-03-01

    Full Text Available This paper details the implementation on the humanoid robot iCub of state-of-the-art algorithms for whole-body control. We regulate the forces between the robot and its surrounding environment to stabilize a desired robot posture. We assume that the forces and torques are exerted on rigid contacts. The validity of this assumption is guaranteed by constraining the contact forces and torques, e.g. the contact forces must belong to the associated friction cones. The implementation of this control strategy requires to estimate the external forces acting on the robot, and the internal joint torques. We then detail algorithms to obtain these estimations when using a robot with an iCub-like sensor set, i.e. distributed six-axis force-torque sensors and whole-body tactile sensors. A general theory for identifying the robot inertial parameters is also presented. From an actuation standpoint, we show how to implement a joint torque control in the case of DC brushless motors. In addition, the coupling mechanism of the iCub torso is investigated. The soundness of the entire control architecture is validated in a real scenario involving the robot iCub balancing and making contacts at both arms.

  8. ANALYTICAL SYNTHESIS OF FORCED PULSE ELECTRONIC DRIVE CONTROL OF A TRACKING SYSTEM

    Directory of Open Access Journals (Sweden)

    A. S. Abufanas

    2017-01-01

    Full Text Available The problem of analytical synthesis of a control signal by a linear dynamical system is considered. As an optimization criterion, it is proposed to consider the transition time of the system from the initial state to a given final state. This type of control is called forced, providing the maximum system speed. The principle of solving this problem is considered on the basis of application of uncertain Lagrange multipliers and the Pontryagin maximum principle. Expressions are obtained for the matrix of transitions of the system and the control signal in a vector form.As an example, the electric drive described by the widespread second-order mathematical model is considered to evaluate the efficiency of the proposed method. Qualitative illustrations of the operability of the proposed approach, obtained by modeling in the Mathcad environment, and quantitative characteristics of the change in the input and output signals of the hypothetical control system are presented. It is shown that the use of forced control does not lead to the output of variables characterizing the state of the system, beyond the limits of admissible values.The use of forced control makes it possible to synthesize the control law in the form of a sequence of rectangular pulses of constant amplitude determined by the power source, variable duty cycle and polarity. This approach can be used for the control of DC-type DC motors used in various tracking systems used on unmanned aerial vehicles. Key words: forced control, target function, electric drive, pulse train. The use of forced control makes it possible to synthesize the control law in the form of a sequence of rectangular pulses of constant amplitude determined by the power source, variable duty cycle and polarity. This approach can be used for the control of DC-type DC motors used in various tracking systems used on unmanned aerial vehicles.

  9. Virtual Control of Prosthetic Hand Based on Grasping Patterns and Estimated Force from Semg

    Directory of Open Access Journals (Sweden)

    Zhu Gao-Ke

    2016-01-01

    Full Text Available Myoelectric prosthetic hands aim to serve upper limb amputees. The myoelectric control of the hand grasp action is a kind of real-time or online method. Thus it is of great necessity to carry on a study of online prosthetic hand electrical control. In this paper, the strategy of simultaneous EMG decoding of grasping patterns and grasping force was realized by controlling a virtual multi-degree-freedom prosthetic hand and a real one-degree-freedom prosthetic hand simultaneously. The former realized the grasping patterns from the recognition of the sEMG pattern. The other implemented the grasping force from sEMG force decoding. The results show that the control method is effective and feasible.

  10. Optimization of Process Parameters of Edge Robotic Deburring with Force Control

    Directory of Open Access Journals (Sweden)

    Burghardt A.

    2016-12-01

    Full Text Available The issues addressed in the paper present a part of the scientific research conducted within the framework of the automation of the aircraft engine part manufacturing processes. The results of the research presented in the article provided information in which tolerances while using a robotic control station with the option of force control we can make edge deburring.

  11. Optimization of Process Parameters of Edge Robotic Deburring with Force Control

    Science.gov (United States)

    Burghardt, A.; Szybicki, D.; Kurc, K.; Muszyńska, M.

    2016-12-01

    The issues addressed in the paper present a part of the scientific research conducted within the framework of the automation of the aircraft engine part manufacturing processes. The results of the research presented in the article provided information in which tolerances while using a robotic control station with the option of force control we can make edge deburring.

  12. Template model inspired leg force feedback based control can assist human walking.

    Science.gov (United States)

    Zhao, Guoping; Sharbafi, Maziar; Vlutters, Mark; van Asseldonk, Edwin; Seyfarth, Andre

    2017-07-01

    We present a novel control approach for assistive lower-extremity exoskeletons. In particular, we implement a virtual pivot point (VPP) template model inspired leg force feedback based controller on a lower-extremity powered exoskeleton (LOPES II) and demonstrate that it can effectively assist humans during walking. It has been shown that the VPP template model is capable of stabilizing the trunk and reproduce a human-like hip torque during the stance phase of walking. With leg force and joint angle feedback inspired by the VPP template model, our controller provides hip and knee torque assistance during the stance phase. A pilot experiment was conducted with four healthy subjects. Joint kinematics, leg muscle electromyography (EMG), and metabolic cost were measured during walking with and without assistance. Results show that, for 0.6 m/s walking, our controller can reduce leg muscle activations, especially for the medial gastrocnemius (about 16.0%), while hip and knee joint kinematics remain similar to the condition without the controller. Besides, the controller also reduces 10% of the net metabolic cost during walking. This paper demonstrates walking assistance benefits of the VPP template model for the first time. The support of human walking is achieved by a force feedback of leg force applied to the control of hip and knee joints. It can help us to provide a framework for investigating walking assistance control in the future.

  13. A novel feedback control system – Controlling the material flow in deep drawing using distributed blank-holder force

    DEFF Research Database (Denmark)

    Endelt, Benny Ørtoft; Tommerup, Søren; Danckert, Joachim

    2013-01-01

    The performance of a feedback control system is often limited by the quality of the model on which it is based, and often the controller design is based on trial and error due to insufficient modeling capabilities. A framework is proposed where the controller design is based on classical state...... on a deep drawing operation where the objective was to control material flow throughout the part using only spatial information regarding flange draw-in. The control system controls both the magnitude and distribution of the blank-holder force. The methodology proved stable and flexible with respect...

  14. Timing at peak force may be the hidden target controlled in continuation and synchronization tapping.

    Science.gov (United States)

    Du, Yue; Clark, Jane E; Whitall, Jill

    2017-05-01

    Timing control, such as producing movements at a given rate or synchronizing movements to an external event, has been studied through a finger-tapping task where timing is measured at the initial contact between finger and tapping surface or the point when a key is pressed. However, the point of peak force is after the time registered at the tapping surface and thus is a less obvious but still an important event during finger tapping. Here, we compared the time at initial contact with the time at peak force as participants tapped their finger on a force sensor at a given rate after the metronome was turned off (continuation task) or in synchrony with the metronome (sensorimotor synchronization task). We found that, in the continuation task, timing was comparably accurate between initial contact and peak force. These two timing events also exhibited similar trial-by-trial statistical dependence (i.e., lag-one autocorrelation). However, the central clock variability was lower at the peak force than the initial contact. In the synchronization task, timing control at peak force appeared to be less variable and more accurate than that at initial contact. In addition to lower central clock variability, the mean SE magnitude at peak force (SEP) was around zero while SE at initial contact (SEC) was negative. Although SEC and SEP demonstrated the same trial-by-trial statistical dependence, we found that participants adjusted the time of tapping to correct SEP, but not SEC, toward zero. These results suggest that timing at peak force is a meaningful target of timing control, particularly in synchronization tapping. This result may explain the fact that SE at initial contact is typically negative as widely observed in the preexisting literature.

  15. 3D force control for robotic-assisted beating heart surgery based on viscoelastic tissue model.

    Science.gov (United States)

    Liu, Chao; Moreira, Pedro; Zemiti, Nabil; Poignet, Philippe

    2011-01-01

    Current cardiac surgery faces the challenging problem of heart beating motion even with the help of mechanical stabilizer which makes delicate operation on the heart surface difficult. Motion compensation methods for robotic-assisted beating heart surgery have been proposed recently in literature, but research on force control for such kind of surgery has hardly been reported. Moreover, the viscoelasticity property of the interaction between organ tissue and robotic instrument further complicates the force control design which is much easier in other applications by assuming the interaction model to be elastic (industry, stiff object manipulation, etc.). In this work, we present a three-dimensional force control method for robotic-assisted beating heart surgery taking into consideration of the viscoelastic interaction property. Performance studies based on our D2M2 robot and 3D heart beating motion information obtained through Da Vinci™ system are provided.

  16. The Director of Mobility Forces' Role in the Command Control of Air Mobility Assets During Humanitarian Relief Operations

    National Research Council Canada - National Science Library

    Bush, Timothy E

    2000-01-01

    ...). Air Force doctrine recommends a command and control (C2) structure that permits the same organizational concept to be used throughout the spectrum of conflict, tailored to suit the specific operational objectives of a Joint Task Force (JFT...

  17. The constrained control of force and position in multi-joint movements.

    Science.gov (United States)

    van Ingen Schenau, G J; Boots, P J; de Groot, G; Snackers, R J; van Woensel, W W

    1992-01-01

    In many arm or leg movements the hand or foot has to exert an external force on the environment. Based on an inverse dynamical analysis of cycling, it is shown that the distribution of net moments in the joints needed to control the direction of the external force is often opposite to the direction of joint displacements associated with this task. Kinetic and kinematic data were obtained from five experienced cyclists during ergometer cycling by means of film analysis and pedal force measurement. An inverse dynamic analysis, based on a linked segments model, yielded net joint moments, joint powers and muscle shortening velocities of eight leg muscles. Activation patterns of the muscles were obtained by means of surface electromyography. The results show that the transfer of rotations in hip, knee and ankle joints into the translation of the pedal is constrained by conflicting requirements. This occurs between the joint moments necessary to contribute to joint power and the moments necessary to establish a direction of the force on the pedal which allows this force to do work on the pedal. Co-activation of mono-articular agonists and their bi-articular antagonists appear to provide a unique solution for these conflicting requirements: bi-articular muscles appear to be able to control the desired direction of the external force on the pedal by adjusting the relative distribution of net moments over the joints while mono-articular muscles appear to be primarily activated when they are in the position to shorten and thus to contribute to positive work. Examples are given to illustrate the universal nature of this constrained control of force (external) and position (joint). Based on this study and published data it is suggested that different processes may underlie the organization of the control of mono- and bi-articular muscles.

  18. Design of Optimal Hybrid Position/Force Controller for a Robot Manipulator Using Neural Networks

    Directory of Open Access Journals (Sweden)

    Vikas Panwar

    2007-01-01

    Full Text Available The application of quadratic optimization and sliding-mode approach is considered for hybrid position and force control of a robot manipulator. The dynamic model of the manipulator is transformed into a state-space model to contain two sets of state variables, where one describes the constrained motion and the other describes the unconstrained motion. The optimal feedback control law is derived solving matrix differential Riccati equation, which is obtained using Hamilton Jacobi Bellman optimization. The optimal feedback control law is shown to be globally exponentially stable using Lyapunov function approach. The dynamic model uncertainties are compensated with a feedforward neural network. The neural network requires no preliminary offline training and is trained with online weight tuning algorithms that guarantee small errors and bounded control signals. The application of the derived control law is demonstrated through simulation with a 4-DOF robot manipulator to track an elliptical planar constrained surface while applying the desired force on the surface.

  19. Comparison of two temperature control techniques in a forced water heater solar system

    Science.gov (United States)

    Hernández, E.; E Guzmán, R.; Santos, A.; Cordoba, E.

    2017-12-01

    a study on the performance of a forced solar heating system in which a comparative analysis of two control strategies, including the classic on-off control and PID control is presented. From the experimental results it was found that the two control strategies show a similar behaviour in the solar heating system forced an approximate settling time of 60 min and over-elongation 2°C for the two control strategies. Furthermore, the maximum temperature in the storage tank was 46°C and the maximum efficiency of flat plate collector was 76.7% given that this efficiency is the ratio of the energy of the radiation on the collector and the energy used to heat water. The efficiency obtained is a fact well accepted because the business efficiencies of flat plate collectors are approximately 70%.

  20. External Periodic Force Control of a Single-Degree-of-Freedom Vibroimpact System

    Directory of Open Access Journals (Sweden)

    Jingyue Wang

    2013-01-01

    Full Text Available A single-degree-of-freedom mechanical model of vibro-impact system is established. Bifurcation and chaos in the system are revealed with the time history diagram, phase trajectory map, and Poincaré map. According to the bifurcation and chaos of the actual vibro-impact system, the paper puts forward external periodic force control strategy. The method of controlling chaos by external periodic force feedback controller is developed to guide chaotic motions towards regular motions. The stability of the control system is also analyzed especially by theory. By selecting appropriate feedback coefficients, the unstable periodic orbits of the original chaotic orbit can be stabilized to the stable periodic orbits. The effectiveness of this control method is verified by numerical simulation.

  1. Design of Active Magnetic Bearing Controllers for Rotors Subjected to Gas Seal Forces

    DEFF Research Database (Denmark)

    Lauridsen, Jonas Skjødt; Santos, Ilmar F.

    2018-01-01

    Proper design of feedback controllers is crucial for ensuring high performance of Active Magnetic Bearing (AMB) supported rotor dynamic systems. Annular seals in those systems can contribute with significant forces, which, in many cases, are hard to model in advance due to complex geometries...... of the seal and multiphase fluids. Hence, it can be challenging to design AMB controllers that will guarantee robust performance for these kinds of systems. This paper demonstrates the design, simulation and experimental results of model based controllers for AMB systems, subjected to dynamic seal forces....... The controllers are found using H-infinity - and µ synthesis and are based on a global rotor dynamic model in-which the seal coefficients are identified in-situ. The controllers are implemented in a rotor-dynamic test facility with two radial AMBs and one annular seal with an adjustable inlet pressure. The seal...

  2. Improved Friction Joint With Self-Locking Grips

    DEFF Research Database (Denmark)

    Costache, Andrei; Glejbøl, Kristian; Sivebæk, Ion Marius

    2016-01-01

    Flexible risers are used in the oil industry to transport liquids and gas from the seafloorto extraction and production equipment at the sea surface. Ongoing research aims at using composite materials instead of steel, in order to reduce weight and increase stiffness. Ensuring an optimal load......-depth understanding of the influence between friction, geometrical parameters,and performance, making it possible to optimize the design. Results show that this grip system offers immediate technical applications, in a variety of conditions....

  3. Multi-muscle FES force control of the human arm for arbitrary goals.

    Science.gov (United States)

    Schearer, Eric M; Liao, Yu-Wei; Perreault, Eric J; Tresch, Matthew C; Memberg, William D; Kirsch, Robert F; Lynch, Kevin M

    2014-05-01

    We present a method for controlling a neuroprosthesis for a paralyzed human arm using functional electrical stimulation (FES) and characterize the errors of the controller. The subject has surgically implanted electrodes for stimulating muscles in her shoulder and arm. Using input/output data, a model mapping muscle stimulations to isometric endpoint forces measured at the subject's hand was identified. We inverted the model of this redundant and coupled multiple-input multiple-output system by minimizing muscle activations and used this inverse for feedforward control. The magnitude of the total root mean square error over a grid in the volume of achievable isometric endpoint force targets was 11% of the total range of achievable forces. Major sources of error were random error due to trial-to-trial variability and model bias due to nonstationary system properties. Because the muscles working collectively are the actuators of the skeletal system, the quantification of errors in force control guides designs of motion controllers for multi-joint, multi-muscle FES systems that can achieve arbitrary goals.

  4. Active Control of Contact Force for a Pantograph-Catenary System

    Directory of Open Access Journals (Sweden)

    Jiqiang Wang

    2016-01-01

    Full Text Available The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

  5. Kinesthetic Force Feedback and Belt Control for the Treadport Locomotion Interface.

    Science.gov (United States)

    Hejrati, Babak; Crandall, Kyle L; Hollerbach, John M; Abbott, Jake J

    2015-01-01

    This paper describes an improved control system for the Treadport immersive locomotion interface, with results that generalize to any treadmill that utilizes an actuated tether to enable self-selected walking speed. A new belt controller is implemented to regulate the user's position; when combined with the user's own volition, this controller also enables the user to naturally self-select their walking speed as they would when walking over ground. A new kinesthetic-force-feedback controller is designed for the tether that applies forces to the user's torso. This new controller is derived based on maintaining the user's sense of balance during belt acceleration, rather than by rendering an inertial force as was done in our prior work. Based on the results of a human-subjects study, the improvements in both controllers significantly contribute to an improved perception of realistic walking on the Treadport. The improved control system uses intuitive dynamic-system and anatomical parameters and requires no ad hoc gain tuning. The control system simply requires three measurements to be made for a given user: the user's mass, the user's height, and the height of the tether attachment point on the user's torso.

  6. Architectural study of the design and operation of advanced force feedback manual controllers

    Science.gov (United States)

    Tesar, Delbert; Kim, Whee-Kuk

    1990-01-01

    A teleoperator system consists of a manual controller, control hardware/software, and a remote manipulator. It was employed in either hazardous or unstructured, and/or remote environments. In teleoperation, the main-in-the-loop is the central concept that brings human intelligence to the teleoperator system. When teleoperation involves contact with an uncertain environment, providing the feeling of telepresence to the human operator is one of desired characteristics of the teleoperator system. Unfortunately, most available manual controllers in bilateral or force-reflecting teleoperator systems can be characterized by their bulky size, high costs, or lack of smoothness and transparency, and elementary architectures. To investigate other alternatives, a force-reflecting, 3 degree of freedom (dof) spherical manual controller is designed, analyzed, and implemented as a test bed demonstration in this research effort. To achieve an improved level of design to meet criteria such as compactness, portability, and a somewhat enhanced force-reflecting capability, the demonstration manual controller employs high gear-ratio reducers. To reduce the effects of the inertia and friction on the system, various force control strategies are applied and their performance investigated. The spherical manual controller uses a parallel geometry to minimize inertial and gravitational effects on its primary task of transparent information transfer. As an alternative to the spherical 3-dof manual controller, a new conceptual (or parallel) spherical 3-dof module is introduced with a full kinematic analysis. Also, the resulting kinematic properties are compared to those of other typical spherical 3-dof systems. The conceptual design of a parallel 6-dof manual controller and its kinematic analysis is presented. This 6-dof manual controller is similar to the Stewart Platform with the actuators located on the base to minimize the dynamic effects. Finally, a combination of the new 3-dof and 6-dof

  7. Reliability of the Bulb Dynamometer for Assessing Grip Strength

    Directory of Open Access Journals (Sweden)

    Colleen Maher

    2018-04-01

    Full Text Available Background: Hand function is an overall indicator of health and is often measured using grip strength. Handheld dynamometry is the most common method of measuring grip strength. The purpose of this study was to determine the inter-rater and test-retest reliability, the reliability of one trial versus three trials, and the preliminary norms for a young adult population using the Baseline® Pneumatic Squeeze Bulb Dynamometer (30 psi. Methods: This study used a one-group methodological design. One hundred and three healthy adults (30 males and 73 females were recruited. Six measurements were collected for each hand per participant. The data was analyzed using Intraclass Correlation Coefficients (ICC two-way effects model (2,2 and paired-samples t-tests. Results: The ICC for inter-rater reliability ranged from 0.955 to 0.977. Conclusion: The results of this study suggest that the bulb dynamometer is a reliable tool to measure grip strength and should be further explored for reliable and valid use in diverse populations and as an alternative to the Jamar dynamometer.

  8. The end-state comfort effect in bimanual grip selection.

    Science.gov (United States)

    Fischman, Mark G; Stodden, David F; Lehman, Davana M

    2003-03-01

    During a unimanual grip selection task in which people pick up a lightweight dowel and place one end against targets at variable heights, the choice of hand grip (overhand vs. underhand) typically depends on the perception of how comfortable the arm will be at the end of the movement: an end-state comfort effect. The two experiments reported here extend this work to bimanual tasks. In each experiment, 26 right-handed participants used their left and right hands to simultaneously pick up two wooden dowels and place either the right or left end against a series of 14 targets ranging from 14 to 210 cm above the floor. These tasks were performed in systematic ascending and descending orders in Experiment 1 and in random order in Expiment 2. Results were generally consistent with predictions of end-state comfort in that, for the extreme highest and lowest targets, participants tended to select opposite grips with each hand. Taken together, our findings are consistent with the concept of constraint hierarchies within a posture-based motion-planning model.

  9. Integrated dynamic and static tactile sensor: focus on static force sensing

    Science.gov (United States)

    Wettels, Nicholas; Pletner, Baruch

    2012-04-01

    Object grasping by robotic hands in unstructured environments demands a sensor that is durable, compliant, and responsive to static and dynamic force conditions. In order for a tactile sensor to be useful for grasp control in these, it should have the following properties: tri-axial force sensing (two shear plus normal component), dynamic event sensing across slip frequencies, compliant surface for grip, wide dynamic range (depending on application), insensitivity to environmental conditions, ability to withstand abuse and good sensing behavior (e.g. low hysteresis, high repeatability). These features can be combined in a novel multimodal tactile sensor. This sensor combines commercial-off-the-shelf MEMS technology with two proprietary force sensors: a high bandwidth device based on PZT technology and low bandwidth device based on elastomers and optics. In this study, we focus on the latter transduction mechanism and the proposed architecture of the completed device. In this study, an embedded LED was utilized to produce a constant light source throughout a layer of silicon rubber which covered a plastic mandrel containing a set of sensitive phototransistors. Features about the contacted object such as center of pressure and force vectors can be extracted from the information in the changing patterns of light. The voltage versus force relationship obtained with this molded humanlike finger had a wide dynamic range that coincided with forces relevant for most human grip tasks.

  10. Enhancement of vortex induced forces and motion through surface roughness control

    Science.gov (United States)

    Bernitsas, Michael M [Saline, MI; Raghavan, Kamaldev [Houston, TX

    2011-11-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to increase Vortex Induced Forces and Motion. Enhancement is needed in such applications as harnessing of clean and renewable energy from ocean/river currents using the ocean energy converter VIVACE (Vortex Induced Vibration for Aquatic Clean Energy).

  11. Reduction of vortex induced forces and motion through surface roughness control

    Science.gov (United States)

    Bernitsas, Michael M; Raghavan, Kamaldev

    2014-04-01

    Roughness is added to the surface of a bluff body in a relative motion with respect to a fluid. The amount, size, and distribution of roughness on the body surface is controlled passively or actively to modify the flow around the body and subsequently the Vortex Induced Forces and Motion (VIFM). The added roughness, when designed and implemented appropriately, affects in a predetermined way the boundary layer, the separation of the boundary layer, the level of turbulence, the wake, the drag and lift forces, and consequently the Vortex Induced Motion (VIM), and the fluid-structure interaction. The goal of surface roughness control is to decrease/suppress Vortex Induced Forces and Motion. Suppression is required when fluid-structure interaction becomes destructive as in VIM of flexible cylinders or rigid cylinders on elastic support, such as underwater pipelines, marine risers, tubes in heat exchangers, nuclear fuel rods, cooling towers, SPAR offshore platforms.

  12. A Comparison between Two Force-Position Controllers with Gravity Compensation Simulated on a Humanoid Arm

    Directory of Open Access Journals (Sweden)

    Giovanni Gerardo Muscolo

    2013-01-01

    Full Text Available The authors propose a comparison between two force-position controllers with gravity compensation simulated on the DEXTER bioinspired robotic arm. The two controllers are both constituted by an internal proportional-derivative (PD closed-loop for the position control. The force control of the two systems is composed of an external proportional (P closed-loop for one system (P system and an external proportional-integrative (PI closed-loop for the other system (PI system. The simulation tests performed with the two systems on a planar representation of the DEXTER, an eight-DOF bioinspired arm, showed that by varying the stiffness of the environment, with a correct setting of parameters, both systems ensure the achievement of the desired force regime and with great precision the desired position. The two controllers do not have large differences in performance when interacting with a lower stiffness environment. In case of an environment with greater rigidity, the PI system is more stable. The subsequent implementation of these control systems on the DEXTER robotic bioinspired arm gives guidance on the design and control optimisation of the arms of the humanoid robot named SABIAN.

  13. Performance and Usability of Various Robotic Arm Control Modes from Human Force Signals

    Directory of Open Access Journals (Sweden)

    Sébastien Mick

    2017-10-01

    Full Text Available Elaborating an efficient and usable mapping between input commands and output movements is still a key challenge for the design of robotic arm prostheses. In order to address this issue, we present and compare three different control modes, by assessing them in terms of performance as well as general usability. Using an isometric force transducer as the command device, these modes convert the force input signal into either a position or a velocity vector, whose magnitude is linearly or quadratically related to force input magnitude. With the robotic arm from the open source 3D-printed Poppy Humanoid platform simulating a mobile prosthesis, an experiment was carried out with eighteen able-bodied subjects performing a 3-D target-reaching task using each of the three modes. The subjects were given questionnaires to evaluate the quality of their experience with each mode, providing an assessment of their global usability in the context of the task. According to performance metrics and questionnaire results, velocity control modes were found to perform better than position control mode in terms of accuracy and quality of control as well as user satisfaction and comfort. Subjects also seemed to favor quadratic velocity control over linear (proportional velocity control, even if these two modes did not clearly distinguish from one another when it comes to performance and usability assessment. These results highlight the need to take into account user experience as one of the key criteria for the design of control modes intended to operate limb prostheses.

  14. Characterization of sliders for efficient force generation of electrostatically controlled linear actuator

    International Nuclear Information System (INIS)

    Nguyen, T A; Konishi, S

    2014-01-01

    In this paper, the characterization of sliders for efficient force generation of an electrostatically controlled linear actuator (ECLIA) is investigated. The ECLIA consists of a piezoactuator (PZT), driving and holding electrodes, multiple sliders and a guide structure. The stepping motion of the sliders is driven by the PZT actuator via an electrostatic clutch mechanism. Thus, multiple sliders can achieve parallel, independent, precise motion, and a large stroke. Previous studies have indicated that the Si bulk slider and Si electrode created an air gap owing to the deformation of the Si electrode. Thus, the Si slider generated a low pushing force. In this study, we propose a fishbone structure mounted on a flexible slider to enhance the pushing force of the slider. The flexible slider, that can deform and fit into the Si electrode to reduce the air gap, results in highly efficient electrostatic-force generation. The fishbone structure improves the longitudinal stiffness of the flexible slider for high pushing-force generation. The results show that the pushing force created by the fishbone slider was three times greater than that of the conventional Si slider. The fishbone and flexible sliders exhibited a high performance for the ECLIA. (paper)

  15. On Optimizing Steering Performance of Multi-axle Vehicle Based on Driving Force Control

    Directory of Open Access Journals (Sweden)

    Wu Zhicheng

    2017-01-01

    Full Text Available The steering performance of multi-axle vehicle with independent driving system is affected by the distribution of the wheel driving force. A nonlinear vehicle dynamics model including magic formula tire model for describing 11 DoF four-axle vehicle with dual-front-axle-steering (DFAS system was presented. The influence of different driving force distribution scheme on the steering performance of the vehicle was analyzed. A control strategy for improving the steady response and transient response of the vehicle steering is proposed. The results show: For the steady response, setting different drive force for internal and external wheels according to the actual steering characteristics of the vehicle can effectively improve its steering characteristics; For the transient response, adopting the zero sideslip angle control strategy and using the PID control algorithm to control the driving force of the outside wheel of tear-two-axle, under angle step input, the vehicle sideslip angle can quickly stabilize to 0 and yaw rate also significantly decreases.

  16. Inertial shear forces and the use of centrifuges in gravity research. What is the proper control?

    NARCIS (Netherlands)

    Loon, van J.J.W.A.; Folgering, H.T.E.; Bouten, C.V.C.; Veldhuijzen, J.P.; Smit, T.H.

    2003-01-01

    Centrifuges are used for 1×g controls in space flight microgravity experiments and in ground based research. Using centrifugation as a tool to generate an Earth like acceleration introduces unwanted inertial shear forces to the sample. Depending on the centrifuge and the geometry of the experiment

  17. A Cost-Effective Atomic Force Microscope for Undergraduate Control Laboratories

    Science.gov (United States)

    Jones, C. N.; Goncalves, J.

    2010-01-01

    This paper presents a simple, cost-effective and robust atomic force microscope (AFM), which has been purposely designed and built for use as a teaching aid in undergraduate controls labs. The guiding design principle is to have all components be open and visible to the students, so the inner functioning of the microscope has been made clear to…

  18. Force-controlled robotic assembly processes of rigid and flexible objects methodologies and applications

    CERN Document Server

    Ghalyan, Ibrahim Fahad Jasim

    2016-01-01

    This book provides comprehensive and integrated approaches for rigid and flexible object assembly. It presents comparison studies with the available force-guided robotic processes and covers contact-state modeling, scheme control strategies, and position searching algorithms. Further, it includes experimental validations for different assembly situations, including those for the assembly of industrial parts taken from the automotive industry. .

  19. Simulation of body force field effects on airfoil separation control and optimization of plasma actuator

    International Nuclear Information System (INIS)

    Abdoli, A; Mirzaee, I; Purmahmod, N; Anvari, A

    2008-01-01

    Among all active flow control methods, EHD, MHD and EMHD are the only methods which operate on the basis of body force induction on flow field. The EHD plasma actuator is the proper method which has been used in various flow control applications recently. In this paper, the effects of different body force fields on different domains have been studied for separation control on NACA 0021 and the results have been discussed. The airflow velocity has been assumed to be 35 m s -1 at a post-stall angle of attack of 23 deg. Three different domains have been used around the airfoil to investigate body forces with different strengths and directions and those which give the best result in separation control have been obtained for each domain. It has been shown that the results could be used for optimizing the plasma actuator by manipulating its electrode configuration. Two non-dimensional numbers, A b and D c , have been obtained and validated by different applied body forces. These numbers have been defined for plasma actuators to show their efficiency in different applications

  20. Simulation of body force field effects on airfoil separation control and optimization of plasma actuator

    Energy Technology Data Exchange (ETDEWEB)

    Abdoli, A; Mirzaee, I; Purmahmod, N [Faculty of Engineering, Urmia University, Urmia (Iran, Islamic Republic of); Anvari, A [Department of Physics, Sharif University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: ab.abdoli@gmail.com

    2008-09-07

    Among all active flow control methods, EHD, MHD and EMHD are the only methods which operate on the basis of body force induction on flow field. The EHD plasma actuator is the proper method which has been used in various flow control applications recently. In this paper, the effects of different body force fields on different domains have been studied for separation control on NACA 0021 and the results have been discussed. The airflow velocity has been assumed to be 35 m s{sup -1} at a post-stall angle of attack of 23 deg. Three different domains have been used around the airfoil to investigate body forces with different strengths and directions and those which give the best result in separation control have been obtained for each domain. It has been shown that the results could be used for optimizing the plasma actuator by manipulating its electrode configuration. Two non-dimensional numbers, A{sub b} and D{sub c}, have been obtained and validated by different applied body forces. These numbers have been defined for plasma actuators to show their efficiency in different applications.

  1. A Novel Approach for Automatic Control of Piezoelectric Elements Used for Lorentz Force Detuning Compensation

    CERN Document Server

    Przygoda, K; Napieralski, A; Grecki, M

    2010-01-01

    Abstract: Linear accelerators such as Free Electron Lasers (FELs) use superconducting (SC) resonant cavities to accelerate electron beam to high energies. TESLA type resonators are extremely sensitive to detuning induced by mechanical deformations – Lorentz force detuning (LFD), mainly due to the extremely high quality factor (Q) of the 1.3 GHz resonance mode, in the range of 1e6. The resulting modulation of a resonance frequency of the cavity makes power consumption and stability performances of the Low-Latency Radio Frequency (LLRF) control more critical. In order to minimize the RF control efforts and desired stabilities, the fast piezoelectric actuators with digital control systems are commonly used. The paper presents a novel approach for automatic control of piezoelectric actuators used for compensation of Lorentz force detuning, the practical application and carried out tests in accelerating module ACC6 in Free-Electron Laser in Hamburg (FLASH).

  2. Variations in Static Force Control and Motor Unit Behavior with Error Amplification Feedback in the Elderly

    Directory of Open Access Journals (Sweden)

    Yi-Ching Chen

    2017-11-01

    Full Text Available Error amplification (EA feedback is a promising approach to advance visuomotor skill. As error detection and visuomotor processing at short time scales decline with age, this study examined whether older adults could benefit from EA feedback that included higher-frequency information to guide a force-tracking task. Fourteen young and 14 older adults performed low-level static isometric force-tracking with visual guidance of typical visual feedback and EA feedback containing augmented high-frequency errors. Stabilogram diffusion analysis was used to characterize force fluctuation dynamics. Also, the discharge behaviors of motor units and pooled motor unit coherence were assessed following the decomposition of multi-channel surface electromyography (EMG. EA produced different behavioral and neurophysiological impacts on young and older adults. Older adults exhibited inferior task accuracy with EA feedback than with typical visual feedback, but not young adults. Although stabilogram diffusion analysis revealed that EA led to a significant decrease in critical time points for both groups, EA potentiated the critical point of force fluctuations <ΔFc2>, short-term effective diffusion coefficients (Ds, and short-term exponent scaling only for the older adults. Moreover, in older adults, EA added to the size of discharge variability of motor units and discharge regularity of cumulative discharge rate, but suppressed the pooled motor unit coherence in the 13–35 Hz band. Virtual EA alters the strategic balance between open-loop and closed-loop controls for force-tracking. Contrary to expectations, the prevailing use of closed-loop control with EA that contained high-frequency error information enhanced the motor unit discharge variability and undermined the force steadiness in the older group, concerning declines in physiological complexity in the neurobehavioral system and the common drive to the motoneuronal pool against force destabilization.

  3. Comparative Effects of Different Balance-Training-Progression Styles on Postural Control and Ankle Force Production: A Randomized Controlled Trial.

    Science.gov (United States)

    Cuğ, Mutlu; Duncan, Ashley; Wikstrom, Erik

    2016-02-01

    Despite the effectiveness of balance training, the exact parameters needed to maximize the benefits of such programs remain unknown. One such factor is how individuals should progress to higher levels of task difficulty within a balance-training program. Yet no investigators have directly compared different balance-training-progression styles. To compare an error-based progression (ie, advance when proficient at a task) with a repetition-based progression (ie, advance after a set amount of repetitions) style during a balance-training program in healthy individuals. Randomized controlled trial. Research laboratory. A total of 28 (16 women, 12 men) physically healthy young adults (age = 21.57 ± 3.95 years, height = 171.60 ± 11.03 cm, weight = 72.96 ± 16.18 kg, body mass index = 24.53 ± 3.7). All participants completed 12 supervised balance-training sessions over 4 weeks. Each session consisted of a combination of dynamic unstable-surface tasks that incorporated a BOSU ball and lasted about 30 minutes. Static balance from an instrumented force plate, dynamic balance as measured via the Star Excursion Balance Test, and ankle force production in all 4 cardinal planes of motion as measured with a handheld dynamometer before and after the intervention. Selected static postural-control outcomes, dynamic postural control, and ankle force production in all planes of motion improved (P .05) for any of the outcome measures. A 4-week balance-training program consisting of dynamic unstable-surface exercises on a BOSU ball improved dynamic postural control and ankle force production in healthy young adults. These results suggest that an error-based balance-training program is comparable with but not superior to a repetition-based balance-training program in improving postural control and ankle force production in healthy young adults.

  4. Preliminary Experimental Results for Indirect Vector-Control of Induction Motor Drives with Forced Dynamics

    Directory of Open Access Journals (Sweden)

    Jan Vittek

    2003-01-01

    Full Text Available The contribution presents an extension of indirect vector control of electric drives employing induction motors to 'Forced Dynamic Control'. This method of control offers an accurate realisation of dynamic response profiles, which can be selected by the user. The developed system can be integrated into a drive with a shaft position encoder or a shaft sensoriess drive, in which only the stator currents are measured. The applied stator voltages are determined by a computed inverter switching algorithm. Simulation results and preliminary experimental results for indirect vector control of an idle running induction motor indicate good agreement with the theoretical predictions.

  5. Evaluation of friction forces between control bars and guide tubes of CAREM fuel element

    International Nuclear Information System (INIS)

    Ghiselli, Alberto M.; Fiori, Jose M.; Yedros, Pablo A.

    2003-01-01

    The design of the MSAC (Mecanismo del Sistema de ajuste y control, Mechanism of the Adjustment and control system, MACS) for CAREM reactor shall consider all loads that the reactor shall support during its operation. Several charges are originated by friction forces produced on contact points of the control Bars/Guide tubes assembly against other components. A test facility was designed and manufactured for the determination of friction components and the damping characteristics of the assembly formed by guide tubes fuel element, the control bars and the guide of the bar of the MACS. In this work a description of the test performed and the results obtained is presented. (author)

  6. Robust Clamping Force Control of an Electro-Mechanical Brake System for Application to Commercial City Buses

    Directory of Open Access Journals (Sweden)

    Sangjune Eum

    2017-02-01

    Full Text Available This paper proposes a sensor-less robust force control method for improving the control performance of an electro-mechanical brake (EMB which is applicable to commercial city buses. The EMB generates the accurate clamping force commanded by a driver through an independent motor control at each wheel instead of using existing mechanical components. In general, an EMB undergoes parameter variation and a backdrivability problem. For this reason, the cascade control strategy (e.g., force-position cascade control structure is proposed and the disturbance observer is employed to enhance control robustness against model variations. Additionally, this paper proposed the clamping force estimation method for a sensor-less control, i.e., the clamping force observer (CFO. Finally, in order to confirm the performance and effectiveness of a proposed robust control method, several experiments are performed and analyzed.

  7. Displacement and force coupling control design for automotive active front steering system

    Science.gov (United States)

    Zhao, Wanzhong; Zhang, Han; Li, Yijun

    2018-06-01

    A displacement and force coupling control design for active front steering (AFS) system of vehicle is proposed in this paper. In order to investigate the displacement and force characteristics of the AFS system of the vehicle, the models of AFS system, vehicle, tire as well as the driver model are introduced. Then, considering the nonlinear characteristics of the tire force and external disturbance, a robust yaw rate control method is designed by applying a steering motor to generate an active steering angle to adjust the yaw stability of the vehicle. Based on mixed H2/H∞ control, the system robustness and yaw rate tracking performance are enforced by H∞ norm constraint and the control effort is captured through H2 norm. In addition, based on the AFS system, a planetary gear set and an assist motor are both added to realize the road feeling control in this paper to dismiss the influence of extra steering angle through a compensating method. Evaluation of the overall system is accomplished by simulations and experiments under various driving condition. The simulation and experiment results show the proposed control system has excellent tracking performance and road feeling performance, which can improve the cornering stability and maneuverability of vehicle.

  8. A 3D Printed Linear Pneumatic Actuator for Position, Force and Impedance Control

    Directory of Open Access Journals (Sweden)

    Jeremy Krause

    2018-05-01

    Full Text Available Although 3D printing has the potential to provide greater customization and to reduce the costs of creating actuators for industrial applications, the 3D printing of actuators is still a relatively new concept. We have developed a pneumatic actuator with 3D-printed parts and placed sensors for position and force control. So far, 3D printing has been used to create pneumatic actuators of the bellows type, thus having a limited travel distance, utilizing low pressures for actuation and being capable of only limited force production and response rates. In contrast, our actuator is linear with a large travel distance and operating at a relatively higher pressure, thus providing great forces and response rates, and this the main novelty of the work. We demonstrate solutions to key challenges that arise during the design and fabrication of 3D-printed linear actuators. These include: (1 the strategic use of metallic parts in high stress areas (i.e., the piston rod; (2 post-processing of the inner surface of the cylinder for smooth finish; (3 piston head design and seal placement for strong and leak-proof action; and (4 sensor choice and placement for position and force control. A permanent magnet placed in the piston head is detected using Hall effect sensors placed along the length of the cylinder to measure the position, and pressure sensors placed at the supply ports were used for force measurement. We demonstrate the actuator performing position, force and impedance control. Our work has the potential to open new avenues for creating less expensive, customizable and capable actuators for industrial and other applications.

  9. Grasping Force Control for a Robotic Hand by Slip Detection Using Developed Micro Laser Doppler Velocimeter

    Directory of Open Access Journals (Sweden)

    Nobutomo Morita

    2018-01-01

    Full Text Available The purpose of this paper is to show the feasibility of grasping force control by feeding back signals of the developed micro-laser Doppler velocimeter (μ-LDV and by discriminating whether a grasped object is slipping or not. LDV is well known as a high response surface velocity sensor which can measure various surfaces—such as metal, paper, film, and so on—thus suggesting the potential application of LDV as a slip sensor for grasping various objects. However, the use of LDV as a slip sensor has not yet been reported because the size of LDVs is too large to be installed on a robotic fingertip. We have solved the size problem and enabled the performance of a feasibility test with a few-millimeter-scale LDV referred to as micro-LDV (μ-LDV by modifying the design which was adopted from MEMS (microelectromechanical systems fabrication process. In this paper, by applying our developed μ-LDV as a slip sensor, we have successfully demonstrated grasping force control with three target objects—aluminum block, wood block, and white acrylic block—considering that various objects made of these materials can be found in homes and factories, without grasping force feedback. We provide proofs that LDV is a new promising candidate slip sensor for grasping force control to execute target grasping.

  10. Grasping Force Control for a Robotic Hand by Slip Detection Using Developed Micro Laser Doppler Velocimeter.

    Science.gov (United States)

    Morita, Nobutomo; Nogami, Hirofumi; Higurashi, Eiji; Sawada, Renshi

    2018-01-23

    The purpose of this paper is to show the feasibility of grasping force control by feeding back signals of the developed micro-laser Doppler velocimeter (μ-LDV) and by discriminating whether a grasped object is slipping or not. LDV is well known as a high response surface velocity sensor which can measure various surfaces-such as metal, paper, film, and so on-thus suggesting the potential application of LDV as a slip sensor for grasping various objects. However, the use of LDV as a slip sensor has not yet been reported because the size of LDVs is too large to be installed on a robotic fingertip. We have solved the size problem and enabled the performance of a feasibility test with a few-millimeter-scale LDV referred to as micro-LDV (μ-LDV) by modifying the design which was adopted from MEMS (microelectromechanical systems) fabrication process. In this paper, by applying our developed μ-LDV as a slip sensor, we have successfully demonstrated grasping force control with three target objects-aluminum block, wood block, and white acrylic block-considering that various objects made of these materials can be found in homes and factories, without grasping force feedback. We provide proofs that LDV is a new promising candidate slip sensor for grasping force control to execute target grasping.

  11. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  12. Integral force feedback control with input shaping: Application to piezo-based scanning systems in ECDLs.

    Science.gov (United States)

    Zhang, Meng; Liu, Zhigang; Zhu, Yu; Bu, Mingfan; Hong, Jun

    2017-07-01

    In this paper, a hybrid control system is developed by integrating the closed-loop force feedback and input shaping method to overcome the problem of the hysteresis and dynamic behavior in piezo-based scanning systems and increase the scanning speed of tunable external cavity diode lasers. The flexible hinge and piezoelectric actuators are analyzed, and a dynamic model of the scanning systems is established. A force sensor and an integral controller are utilized in integral force feedback (IFF) to directly augment the damping of the piezoelectric scanning systems. Hysteresis has been effectively eliminated, but the mechanical resonance is still evident. Noticeable residual vibration occurred after the inflection points and then gradually disappeared. For the further control of mechanical resonance, based on the theory of minimum-acceleration trajectory planning, the time-domain input shaping method was developed. The turning sections of a scanning trajectory are replaced by smooth curves, while the linear sections are retained. The IFF method is combined with the input shaping method to control the non-linearity and mechanical resonance in high-speed piezo-based scanning systems. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach.

  13. The influence of respiratory acid-base changes on muscle performance and excitability of the sarcolemma during strenuous intermittent hand grip exercise.

    Science.gov (United States)

    Hilbert, M; Shushakov, V; Maassen, N

    2012-02-01

    Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO(2) rebreathing, alkalosis by hyperventilation, or control. The Pco(2), pH, K(+) concentration ([K(+)]), and Na(+) concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis (P alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition (P Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.

  14. Force analysis of the advanced neutron source control rod drive latch mechanism

    International Nuclear Information System (INIS)

    Damiano, B.

    1989-01-01

    The Advanced Neutron Source reactor (ANS), a proposed Department of Energy research reactor currently undergoing conceptual design at the Oak Ridge National Laboratory (ORNL), will generate a thermal neutron flux approximating 10 30 M -2 emdash S -1 . The compact core necessary to produce this flux provides little space for the shim safety control rods, which are located in the central annulus of the core. Without proper control rod drive design, the control rod drive magnets (which hold the control rod latch in a ready-to-scram position) may be unable to support the required load due to their restricted size. This paper describes the force analysis performed on the control rod latch mechanism to determine the fraction of control rod weight transferred to the drive magnet. This information will be useful during latch, control rod drive and magnet design. 5 refs., 12 figs

  15. Kinematic control of aerodynamic forces on an inclined flapping wing with asymmetric strokes

    International Nuclear Information System (INIS)

    Park, Hyungmin; Choi, Haecheon

    2012-01-01

    In the present study, we conduct an experiment using a one-paired dynamically scaled model of an insect wing, to investigate how asymmetric strokes with different wing kinematic parameters are used to control the aerodynamics of a dragonfly-like inclined flapping wing in still fluid. The kinematic parameters considered are the angles of attack during the mid-downstroke (α md ) and mid-upstroke (α mu ), and the duration (Δτ) and time of initiation (τ p ) of the pitching rotation. The present dragonfly-like inclined flapping wing has the aerodynamic mechanism of unsteady force generation similar to those of other insect wings in a horizontal stroke plane, but the detailed effect of the wing kinematics on the force control is different due to the asymmetric use of the angle of attack during the up- and downstrokes. For example, high α md and low α mu produces larger vertical force with less aerodynamic power, and low α md and high α mu is recommended for horizontal force (thrust) production. The pitching rotation also affects the aerodynamics of a flapping wing, but its dynamic rotational effect is much weaker than the effect from the kinematic change in the angle of attack caused by the pitching rotation. Thus, the influences of the duration and timing of pitching rotation for the present inclined flapping wing are found to be very different from those for a horizontal flapping wing. That is, for the inclined flapping motion, the advanced and delayed rotations produce smaller vertical forces than the symmetric one and the effect of pitching duration is very small. On the other hand, for a specific range of pitching rotation timing, delayed rotation requires less aerodynamic power than the symmetric rotation. As for the horizontal force, delayed rotation with low α md and high α mu is recommended for long-duration flight owing to its high efficiency, and advanced rotation should be employed for hovering flight for nearly zero horizontal force. The present

  16. Teleoperator comfort and psychometric stability: Criteria for limiting master-controller forces of operation and feedback during telemanipulation

    Science.gov (United States)

    Wiker, Steven F.; Hershkowitz, Elaine; Zik, John

    1989-01-01

    The following question is addressed: How much force should operators exert, or experience, when operating a telemanipulator master-controller for sustained periods without encountering significant fatigue and discomfort, and without loss of stability in psychometric perception of force. The need to minimize exertion demands to avoid fatigue is diametrically opposed by the need to present a wide range of force stimuli to enhance perception of applied or reflected forces. For 104 minutes subjects repetitiously performed a series of 15 s isometric pinch grasps; controlled at 5, 15, and 25 percent of their maximum voluntary strength. Cyclic pinch grasps were separated by rest intervals of 7.5 and 15 s. Upon completion of every 10 minute period, subjects interrupted grasping activities to gage the intensity of fatigue and discomfort in the hand and forearm using a cross-modal matching technique. A series of psychometric tests were then conducted to determine accuracy and stability in the subject's perception of force experienced. Results showed that onset of sensations of discomfort and fatigue were dependent upon the magnitude of grasp force, work/rest ratio, and progression of task. Declines in force magnitude estimation slopes, indicating a reduction in force perception sensitivity, occurred with increased grasp force when work/rest ratios were greater than 1.0. Specific recommendations for avoiding discomfort and shifts in force perception, by limiting pinch grasp force required for master-controller operation and range of force reflection or work/rest ratios, are provided.

  17. Highly-Integrated Hydraulic Smart Actuators and Smart Manifolds for High-Bandwidth Force Control

    Directory of Open Access Journals (Sweden)

    Victor Barasuol

    2018-06-01

    Full Text Available Hydraulic actuation is the most widely used alternative to electric motors for legged robots and manipulators. It is often selected for its high power density, robustness and high-bandwidth control performance that allows the implementation of force/impedance control. Force control is crucial for robots that are in contact with the environment, since it enables the implementation of active impedance and whole body control that can lead to a better performance in known and unknown environments. This paper presents the hydraulic Integrated Smart Actuator (ISA developed by Moog in collaboration with IIT, as well as smart manifolds for rotary hydraulic actuators. The ISA consists of an additive-manufactured body containing a hydraulic cylinder, servo valve, pressure/position/load/temperature sensing, overload protection and electronics for control and communication. The ISA v2 and ISA v5 have been specifically designed to fit into the legs of IIT’s hydraulic quadruped robots HyQ and HyQ-REAL, respectively. The key features of these components tackle 3 of today’s main challenges of hydraulic actuation for legged robots through: (1 built-in controllers running inside integrated electronics for high-performance control, (2 low-leakage servo valves for reduced energy losses, and (3 compactness thanks to metal additive manufacturing. The main contributions of this paper are the derivation of the representative dynamic models of these highly integrated hydraulic servo actuators, a control architecture that allows for high-bandwidth force control and their experimental validation with application-specific trajectories and tests. We believe that this is the first work that presents additive-manufactured, highly integrated hydraulic smart actuators for robotics.

  18. Comparison of timing and force control of foot tapping between elderly and young subjects.

    Science.gov (United States)

    Takimoto, Koji; Takebayashi, Hideaki; Miyamoto, Kenzo; Takuma, Yutaka; Inoue, Yoshikazu; Miyamoto, Shoko; Okabe, Takao; Okuda, Takahiro; Kaba, Hideto

    2016-06-01

    [Purpose] To examine the ability of young and elderly individuals to control the timing and force of periodic sequential foot tapping. [Subjects and Methods] Participants were 10 young (age, 22.1 ± 4.3 years) and 10 elderly individuals (74.8 ± 6.7 years) who were healthy and active. The foot tapping task consisted of practice (stimulus-synchronized tapping with visual feedback) and recall trials (self-paced tapping without visual feedback), periodically performed in this order, at 500-, 1,000-, and 2,000-ms target interstimulus-onset intervals, with a target force of 20% maximum voluntary contraction of the ankle plantar-flexor muscle. [Results] The coefficients of variation of force and intertap interval, used for quantifying the steadiness of the trials, were significantly greater in the elderly than in the young individuals. At the 500-ms interstimulus-onset interval, age-related effects were observed on the normalized mean absolute error of force, which was used to quantify the accuracy of the trials. The coefficients of variation of intertap interval for elderly individuals were significantly greater in the practice than in the recall trials at the 500- and 1,000-ms interstimulus-onset intervals. [Conclusion] The elderly individuals exhibited greater force and timing variability than the young individuals and showed impaired visuomotor processing during foot tapping sequences.

  19. Effective method to control the levitation force and levitation height in a superconducting maglev system

    International Nuclear Information System (INIS)

    Yang Peng-Tao; Yang Wan-Min; Wang Miao; Li Jia-Wei; Guo Yu-Xia

    2015-01-01

    The influence of the width of the middle magnet in the permanent magnet guideways (PMGs) on the levitation force and the levitation height of single-domain yttrium barium copper oxide (YBCO) bulks has been investigated at 77 K under the zero field cooled (ZFC) state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications. (paper)

  20. Discrimination of handlebar grip samples by fourier transform infrared microspectroscopy analysis and statistics

    Directory of Open Access Journals (Sweden)

    Zeyu Lin

    2017-01-01

    Full Text Available In this paper, the authors presented a study on the discrimination of handlebar grip samples, to provide effective forensic science service for hit and run traffic cases. 50 bicycle handlebar grip samples, 49 electric bike handlebar grip samples, and 96 motorcycle handlebar grip samples have been randomly collected by the local police in Beijing (China. Fourier transform infrared microspectroscopy (FTIR was utilized as analytical technology. Then, target absorption selection, data pretreatment, and discrimination of linked samples and unlinked samples were chosen as three steps to improve the discrimination of FTIR spectrums collected from different handlebar grip samples. Principal component analysis and receiver operating characteristic curve were utilized to evaluate different data selection methods and different data pretreatment methods, respectively. It is possible to explore the evidential value of handlebar grip residue evidence through instrumental analysis and statistical treatments. It will provide a universal discrimination method for other forensic science samples as well.

  1. Writing forces associated with four pencil grasp patterns in grade 4 children.

    Science.gov (United States)

    Schwellnus, Heidi; Carnahan, Heather; Kushki, Azadeh; Polatajko, Helene; Missiuna, Cheryl; Chau, Tom

    2013-01-01

    OBJECTIVE. We investigated differences in handwriting kinetics, speed, and legibility among four pencil grasps after a 10-min copy task. METHOD. Seventy-four Grade 4 students completed a handwriting assessment before and after a copy task. Grip and axial forces were measured with an instrumented stylus and force-sensitive tablet. We used multiple linear regression to analyze the relationship between grasp pattern and grip and axial forces. RESULTS. We found no kinetic differences among grasps, whether considered individually or grouped by the number of fingers on the barrel. However, when grasps were grouped according to the thumb position, the adducted grasps exhibited higher mean grip and axial forces. CONCLUSION. Grip forces were generally similar across the different grasps. Kinetic differences resulting from thumb position seemed to have no bearing on speed and legibility. Interventions for handwriting difficulties should focus more on speed and letter formation than on grasp pattern. Copyright © 2013 by the American Occupational Therapy Association, Inc.

  2. Proportional Derivative Active Force Control for “X” Configuration Quadcopter

    Directory of Open Access Journals (Sweden)

    Niam Tamami

    2014-12-01

    Full Text Available This paper present a control method “x” configuration quadcopter. The control method used PDAFC (Proportional Derivative Active Force Control. PD is used to stabilize quadcopter, and AFC is used to reject uncertainty disturbance (e.g. wind by estimate disturbance torque value of quadcopter. By adding PD with AFC, better result is obtained, AFC can minimize uncertainty disturbance effect. The sensitivity toward uncertainty disturbance can be set from sensitivity constant to get best performance of disturbance rejection. Stability analysis of PDAFC was evaluated by Lyapunov stability theory.

  3. Force Control for a Pneumatic Cylinder Using Generalized Predictive Controller Approach

    OpenAIRE

    Mohd Faudzi, Ahmad ’Athif; Mustafa, Nu’man Din; Osman, Khairuddin

    2014-01-01

    Pneumatic cylinder is a well-known device because of its high power to weight ratio, easy use, and environmental safety. Pneumatic cylinder uses air as its power source and converts it to a possible movement such as linear and rotary movement. In order to control the pneumatic cylinder, controller algorithm is needed to control the on-off solenoid valve with encoder and pressure sensor as the feedback inputs. In this paper, generalized predictive controller (GPC) is proposed as the control st...

  4. Manipulating Microrobots Using Balanced Magnetic and Buoyancy Forces

    Directory of Open Access Journals (Sweden)

    Lin Feng

    2018-01-01

    Full Text Available We present a novel method for the three-dimensional (3D control of microrobots within a microfluidic chip. The microrobot body contains a hollow space, producing buoyancy that allows it to float in a microfluidic environment. The robot moves in the z direction by balancing magnetic and buoyancy forces. In coordination with the motion of stages in the xy plane, we achieved 3D microrobot control. A microgripper designed to grasp micron-scale objects was attached to the front of the robot, allowing it to hold and deliver micro-objects in three dimensions. The microrobot had four degrees of freedom and generated micronewton-order forces. We demonstrate the microrobot’s utility in an experiment in which it grips a 200 μm particle and delivers it in a 3D space.

  5. Force control tasks with pure haptic feedback promote short-term focused attention.

    Science.gov (United States)

    Wang, Dangxiao; Zhang, Yuru; Yang, Xiaoxiao; Yang, Gaofeng; Yang, Yi

    2014-01-01

    Focused attention has great impact on our quality of life. Our learning, social skills and even happiness are closely intertwined with our capacity for focused attention. Attention promotion is replete with examples of training-induced increases in attention capability, most of which rely on visual and auditory stimulation. Pure haptic stimulation to increase attention capability is rarely found. We show that accurate force control tasks with pure haptic feedback enhance short-term focused attention. Participants were trained by a force control task in which information from visual and auditory channels was blocked, and only haptic feedback was provided. The trainees were asked to exert a target force within a pre-defined force tolerance for a specific duration. The tolerance was adaptively modified to different levels of difficulty to elicit full participant engagement. Three attention tests showed significant changes in different aspects of focused attention in participants who had been trained as compared with those who had not, thereby illustrating the role of haptic-based sensory-motor tasks in the promotion of short-term focused attention. The findings highlight the potential value of haptic stimuli in brain plasticity and serve as a new tool to extend existing computer games for cognitive enhancement.

  6. Finger pad friction and its role in grip and touch

    Science.gov (United States)

    Adams, Michael J.; Johnson, Simon A.; Lefèvre, Philippe; Lévesque, Vincent; Hayward, Vincent; André, Thibaut; Thonnard, Jean-Louis

    2013-01-01

    Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick–slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function. PMID:23256185

  7. Finger pad friction and its role in grip and touch.

    Science.gov (United States)

    Adams, Michael J; Johnson, Simon A; Lefèvre, Philippe; Lévesque, Vincent; Hayward, Vincent; André, Thibaut; Thonnard, Jean-Louis

    2013-03-06

    Many aspects of both grip function and tactile perception depend on complex frictional interactions occurring in the contact zone of the finger pad, which is the subject of the current review. While it is well established that friction plays a crucial role in grip function, its exact contribution for discriminatory touch involving the sliding of a finger pad is more elusive. For texture discrimination, it is clear that vibrotaction plays an important role in the discriminatory mechanisms. Among other factors, friction impacts the nature of the vibrations generated by the relative movement of the fingertip skin against a probed object. Friction also has a major influence on the perceived tactile pleasantness of a surface. The contact mechanics of a finger pad is governed by the fingerprint ridges and the sweat that is exuded from pores located on these ridges. Counterintuitively, the coefficient of friction can increase by an order of magnitude in a period of tens of seconds when in contact with an impermeably smooth surface, such as glass. In contrast, the value will decrease for a porous surface, such as paper. The increase in friction is attributed to an occlusion mechanism and can be described by first-order kinetics. Surprisingly, the sensitivity of the coefficient of friction to the normal load and sliding velocity is comparatively of second order, yet these dependencies provide the main basis of theoretical models which, to-date, largely ignore the time evolution of the frictional dynamics. One well-known effect on taction is the possibility of inducing stick-slip if the friction decreases with increasing sliding velocity. Moreover, the initial slip of a finger pad occurs by the propagation of an annulus of failure from the perimeter of the contact zone and this phenomenon could be important in tactile perception and grip function.

  8. Knowledge-Based Trajectory Error Pattern Method Applied to an Active Force Control Scheme

    Directory of Open Access Journals (Sweden)

    Endra Pitowarno, Musa Mailah, Hishamuddin Jamaluddin

    2012-08-01

    Full Text Available The active force control (AFC method is known as a robust control scheme that dramatically enhances the performance of a robot arm particularly in compensating the disturbance effects. The main task of the AFC method is to estimate the inertia matrix in the feedback loop to provide the correct (motor torque required to cancel out these disturbances. Several intelligent control schemes have already been introduced to enhance the estimation methods of acquiring the inertia matrix such as those using neural network, iterative learning and fuzzy logic. In this paper, we propose an alternative scheme called Knowledge-Based Trajectory Error Pattern Method (KBTEPM to suppress the trajectory track error of the AFC scheme. The knowledge is developed from the trajectory track error characteristic based on the previous experimental results of the crude approximation method. It produces a unique, new and desirable error pattern when a trajectory command is forced. An experimental study was performed using simulation work on the AFC scheme with KBTEPM applied to a two-planar manipulator in which a set of rule-based algorithm is derived. A number of previous AFC schemes are also reviewed as benchmark. The simulation results show that the AFC-KBTEPM scheme successfully reduces the trajectory track error significantly even in the presence of the introduced disturbances.Key Words:  Active force control, estimated inertia matrix, robot arm, trajectory error pattern, knowledge-based.

  9. Site-controlled quantum dots fabricated using an atomic-force microscope assisted technique

    Directory of Open Access Journals (Sweden)

    Sakuma Y

    2006-01-01

    Full Text Available AbstractAn atomic-force microscope assisted technique is developed to control the position and size of self-assembled semiconductor quantum dots (QDs. Presently, the site precision is as good as ± 1.5 nm and the size fluctuation is within ± 5% with the minimum controllable lateral diameter of 20 nm. With the ability of producing tightly packed and differently sized QDs, sophisticated QD arrays can be controllably fabricated for the application in quantum computing. The optical quality of such site-controlled QDs is found comparable to some conventionally self-assembled semiconductor QDs. The single dot photoluminescence of site-controlled InAs/InP QDs is studied in detail, presenting the prospect to utilize them in quantum communication as precisely controlled single photon emitters working at telecommunication bands.

  10. Multivariable H force/level control of the twin-roller strip caster

    International Nuclear Information System (INIS)

    Cavazos, A.; Edwards, J.B.

    2005-01-01

    Twin-roller steel strip casters may offer some advantages with respect to classical continuous casting hot rolling processes. Some works have reported control aspects of this process and although the process has been found to be highly interactive and non-linear, little or no attention has been given to its multivariable characteristics. The purpose of this work is to design a multivariable control capable of decoupling the system. This paper presents some important aspects of the strip caster modeling and reports the simulation results of the application of the multivariable H-optimal control for nominal performance to force/level control. Various controllers have been designed for different pool level heights and it is shown that they can decouple the system, allowing the application of PI decentralized controllers to considerably improve performance. (author)

  11. Improvements in or relating to gripping means for handling nuclear reactor fuel assemblies

    International Nuclear Information System (INIS)

    Batjukov, V.I.; Vjugov, O.N.; Fadeev, A.I.; Shkhian, T.G.

    1980-01-01

    A gripping means for handling fuel assemblies, the heads of which are internally recessed to receive gripping jaws, forms part of a reactor refuelling machine and is telescopically accommodated within a manipulator tube of the machine. A through hole is provided to allow cooling medium to be passed through the fuel assemblies to remove afterheat when the gripping means is used to transfer assemblies from a reactor core to spent fuel storage sockets. (author)

  12. Memory-guided force output is associated with self-reported ADHD symptoms in young adults.

    Science.gov (United States)

    Neely, Kristina A; Chennavasin, Amanda P; Yoder, Arie; Williams, Genevieve K R; Loken, Eric; Huang-Pollock, Cynthia L

    2016-11-01

    Attention-deficit/hyperactivity disorder (ADHD) is the most commonly diagnosed mental health disorder in childhood and persists into adulthood in up to 65 % of cases. ADHD is associated with adverse outcomes such as the ability to gain and maintain employment and is associated with an increased risk for substance abuse obesity workplace injuries and traffic accidents A majority of diagnosed children have motor deficits; however, few studies have examined motor deficits in young adults. This study provides a novel examination of visuomotor control of grip force in young adults with and without ADHD. Participants were instructed to maintain force production over a 20-second trial with and without real-time visual feedback about their performance. The results demonstrated that when visual feedback was available, adults with ADHD produced slightly higher grip force than controls. However, when visual feedback was removed, adults with ADHD had a faster rate of decay of force, which was associated with ADHD symptom severity and trait impulsivity. These findings suggest that there may be important differences in the way that adults with ADHD integrate visual feedback during continuous motor tasks. These may account for some of the motor impairments reported in children with ADHD. These deficits could result from (1) dysfunctional sensory motor integration and/or (2) deficits in short-term visuomotor memory.

  13. GRIP Database original data - GRIPDB | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available switchLanguage; BLAST Search Image Search Home About Archive Update History Data List Contact us GRI...PDB GRIP Database original data Data detail Data name GRIP Database original data DOI 10....18908/lsdba.nbdc01665-006 Description of data contents GRIP Database original data It consists of data table...s and sequences. Data file File name: gripdb_original_data.zip File URL: ftp://ftp.biosciencedbc.jp/archive/gripdb/LATEST/gri...e Database Description Download License Update History of This Database Site Policy | Contact Us GRIP Database original data - GRIPDB | LSDB Archive ...

  14. Effects of hand grip exercise on shoulder joint internal rotation and external rotation peak torque.

    Science.gov (United States)

    Lee, Dong-Rour; Jong-Soon Kim, Laurentius

    2016-08-10

    The goal of this study is to analyze the effects of hand grip training on shoulder joint internal rotation (IR)/external rotation (ER) peak torque for healthy people. The research was conducted on 23 healthy adults in their 20 s-30 s who volunteered to participate in the experiment. Hand grip power test was performed on both hands of the research subjects before/after the test to study changes in hand grip power. Isokinetic machine was used to measure the concentric IRPT (internal rotation peak torque) and concentric ERPT (external rotation peak torque) at the velocity of 60°/sec, 90°/sec, and 180°/sec before/after the test. Hand grip training was performed daily on the subject's right hand only for four weeks according to exercise program. Finally, hand grip power of both hands and the maximum torque values of shoulder joint IR/ER were measured before/after the test and analyzed. There was a statistically significant difference in the hand grip power of the right hand, which was subject to hand grip training, after the experiment. Also, statistically significant difference for shoulder ERPT was found at 60°/sec. Hand grip training has a positive effect on shoulder joint IRPT/ERPT and therefore can help strengthen muscles around the shoulder without using weight on the shoulder. Consequently, hand grip training would help maintain strengthen the muscles around the shoulder in the early phase of rehabilitation process after shoulder surgery.

  15. Real-time changes in corticospinal excitability related to motor imagery of a force control task

    DEFF Research Database (Denmark)

    Tatemoto, Tsuyoshi; Tsuchiya, Junko; Numata, Atsuki

    2017-01-01

    Objective To investigate real-time excitability changes in corticospinal pathways related to motor imagery in a changing force control task, using transcranial magnetic stimulation (TMS). Methods Ten healthy volunteers learnt to control the contractile force of isometric right wrist dorsiflexion...... in order to track an on-screen sine wave form. Participants performed the trained task 40 times with actual muscle contraction in order to construct the motor image. They were then instructed to execute the task without actual muscle contraction, but by imagining contraction of the right wrist...... in dorsiflexion. Motor evoked potentials (MEPs), induced by TMS in the right extensor carpi radialis muscle (ECR) and flexor carpi radialis muscle (FCR), were measured during motor imagery. MEPs were induced at five time points: prior to imagery, during the gradual generation of the imaged wrist dorsiflexion...

  16. Resonant passive–active vibration absorber with integrated force feedback control

    International Nuclear Information System (INIS)

    Høgsberg, Jan; Brodersen, Mark L; Krenk, Steen

    2016-01-01

    A general format of a two-terminal vibration absorber is constructed by placing a passive unit in series with a hybrid unit, composed of an active actuator in parallel with a second passive element. The displacement of the active actuator is controlled by an integrated feedback control with the difference in force between the two passive elements as input. This format allows passive and active contributions to be combined arbitrarily within the hybrid unit, which results in a versatile absorber format with guaranteed closed-loop stability. This is demonstrated for resonant absorbers with inertia realized passively by a mechanical inerter or actively by the integrated force feedback. Accurate calibration formulae are presented for two particular absorber configurations and the performance is subsequently demonstrated with respect to both equal modal damping and effective response reduction. (technical note)

  17. Optimal arm posture control and tendon traction forces of a coupled tendon-driven manipulator

    International Nuclear Information System (INIS)

    Ma, Shugen

    1997-01-01

    In this study, the optimum arm posture of a coupled tendon-driven multijoint manipulator arm (or CT Arm) at maximum payload output was derived and the corresponding tendon traction forces were also analyzed, during management of a heavy payload by the manipulator in a gravity environment. The CT Arm is special tendon traction transmission mechanism in which a pair of tendons used to drive a joint is pulled from base actuators via pulleys mounted on the base-side joints. This mechanism enables optimal utilization of the coupled drive function of tendon traction forces and thus enables the lightweight manipulator to exhibit large payload capability. The properties of the CT Arm mechanism are elucidated by the proposed optimal posture control scheme. Computer simulation was also executed to verify the validity of the proposed control scheme. (author)

  18. AN INTELLIGENT NEURO-FUZZY TERMINAL SLIDING MODE CONTROL METHOD WITH APPLICATION TO ATOMIC FORCE MICROSCOPE

    Directory of Open Access Journals (Sweden)

    Seied Yasser Nikoo

    2016-11-01

    Full Text Available In this paper, a neuro-fuzzy fast terminal sliding mode control method is proposed for controlling a class of nonlinear systems with bounded uncertainties and disturbances. In this method, a nonlinear terminal sliding surface is firstly designed. Then, this sliding surface is considered as input for an adaptive neuro-fuzzy inference system which is the main controller. A proportinal-integral-derivative controller is also used to asist the neuro-fuzzy controller in order to improve the performance of the system at the begining stage of control operation. In addition, bee algorithm is used in this paper to update the weights of neuro-fuzzy system as well as the parameters of the proportinal-integral-derivative controller. The proposed control scheme is simulated for vibration control in a model of atomic force microscope system and the results are compared with conventional sliding mode controllers. The simulation results show that the chattering effect in the proposed controller is decreased in comparison with the sliding mode and the terminal sliding mode controllers. Also, the method provides the advantages of fast convergence and low model dependency compared to the conventional methods.

  19. Damping-controlled fluidelastic instability forces in multi-span tubes with loose supports

    International Nuclear Information System (INIS)

    Hassan, Marwan A.; Rogers, Robert J.; Gerber, Andrew G.

    2011-01-01

    This paper presents simulations of a loosely supported multi-span tube subjected to turbulence and fluidelastic instability forces in order to compare several time-domain fluid force models simulating the damping-controlled fluidelastic instability mechanism in tube arrays. These models include the negative damping model based on the Connors equation, fluid force coefficient-based models (Chen; Tanaka and Takahara), and two semi-analytical models (Price and Paidoussis; and Lever and Weaver). Time domain modelling challenges for each of these theories are discussed. The implemented models are validated against available experimental data. The linear simulations (without tube/support clearance) show that the Connors-equation based model exhibits the most conservative prediction of the critical flow velocity when the recommended design values for the Connors equation are used. The models are then utilized to simulate the nonlinear response of a three-span cantilever tube in a lattice bar support subjected to air crossflow. The tube is subjected to a single-phase flow passing over the spans where the flow velocity and the support clearance are varied. Special attention is paid to the tube/support interaction parameters that affect wear, such as impact forces, contact ratio, and normal work rate. As was seen for the linear cases, the reduced flow velocity at the instability threshold differs for the fluid force models considered. The investigated models do, however, exhibit similar response characteristics for the impact force, tip lift response, and work rate, except for the Connors-based model that overestimates the response and the tube/support interaction parameters for the loose support case, especially at large clearances.

  20. Command and Control Architectures for Autonomous Micro-Robotic Forces - FY-2000 Project Report

    Energy Technology Data Exchange (ETDEWEB)

    Dudenhoeffer, Donald Dean

    2001-04-01

    Advances in Artificial Intelligence (AI) and micro-technologies will soon give rise to production of large-scale forces of autonomous micro-robots with systems of innate behaviors and with capabilities of self-organization and real world tasking. Such organizations have been compared to schools of fish, flocks of birds, herds of animals, swarms of insects, and military squadrons. While these systems are envisioned as maintaining a high degree of autonomy, it is important to understand the relationship of man with such machines. In moving from research studies to the practical deployment of large-scale numbers of robots, one of critical pieces that must be explored is the command and control architecture for humans to re-task and also inject global knowledge, experience, and intuition into the force. Tele-operation should not be the goal, but rather a level of adjustable autonomy and high-level control. If a herd of sheep is comparable to the collective of robots, then the human element is comparable to the shepherd pulling in strays and guiding the herd in the direction of greener pastures. This report addresses the issues and development of command and control for largescale numbers of autonomous robots deployed as a collective force.

  1. Force Plate Assessment of Quiet Standing Balance Control: Perspectives on Clinical Application within Stroke Rehabilitation

    Directory of Open Access Journals (Sweden)

    Avril Mansfield

    2015-01-01

    Full Text Available Assessment of balance control is essential to guide physical rehabilitation poststroke. However, current observational assessment tools available to physiotherapists provide limited information about underlying dyscontrol. This paper describes a force plate-based assessment of quiet standing balance control that we have implemented for individuals attending inpatient stroke rehabilitation. The assessment uses two force plates to measure location of ground reaction forces to maintain stability in quiet standing in five conditions (eyes open, eyes closed, standing symmetrically, and maximal loading on the less-affected and more-affected limbs. Measures of interest are variability of the centers of pressure under each foot and both feet combined, weight-bearing asymmetry, and correlation of center of pressure fluctuations between limbs. We present representative values for the above-mentioned measures and case examples to illustrate how the assessment can reveal patient-specific balance control problems and direct treatment. We identify limitations to our current assessment and recommendations for future research.

  2. The Effects of Age, Gender, and Hand on Force Control Capabilities of Healthy Adults.

    Science.gov (United States)

    Lee, Baekhee; Lee, Mina; Yoh, Myeung Sook; You, Heecheon; Park, Hyunji; Jung, Kihyo; Lee, Byung Hwa; Na, Duk L; Kim, Geon Ha

    2015-12-01

    The present study examined the effects of age (20s to 70s), gender (male and female), and hand (dominant and nondominant) on force control capabilities (FCCs) in four force control phases (initiation, development, maintenance, and termination). Normative data of FCCs by force control phase are needed for various populations in age and gender to identify a type of motor performance reduction and its severity. FCCs of 360 participants (30 for each combination of age group and gender) were measured using a finger dynamometer and quantified in terms of initiation time (IT), development time (DT), maintenance error (ME), and termination time (TT). Although gradual increases (1%~28%) by age were shown in IT, DT, and TT, a dramatic increase in ME was observed among participants in their 50s (26%), 60s (68%), and 70s (160%) compared to those in their 20s~40s. The most distinctive interaction effect of age and gender was found in ME out of the four FCC measures. Lastly, hand and its related interactions were not found significant. Normative FCC data were established for four age groups (20s~40s, 50s, 60s, and 70s) and gender. The normative FCC data can be used for evaluating an individual's motor performance, screening patients with brain disorders, and designing input devices triggered and/or operated by the finger. © 2015, Human Factors and Ergonomics Society.

  3. Magnetic Field Equivalent Current Analysis-Based Radial Force Control for Bearingless Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Huangqiu Zhu

    2015-05-01

    Full Text Available Bearingless permanent magnet synchronous motors (BPMSMs, with all advantages of permanent magnet motors (PMSMs and magnetic bearings, have become an important research direction in the bearingless motor field. To realize a stable suspension for the BPMSM, accurate decoupling control between the electromagnetic torque and radial suspension force is indispensable. In this paper, a concise and reliable analysis method based on a magnetic field equivalent current is presented. By this analysis method, the operation principle is analyzed theoretically, and the necessary conditions to produce a stable radial suspension force are confirmed. In addition, mathematical models of the torque and radial suspension force are established which is verified by the finite element analysis (FEA software ANSYS. Finally, an experimental prototype of a 2-4 poles surface-mounted BPMSM is tested with the customized control strategy. The simulation and experimental results have shown that the motor has good rotation and suspension performance, and validated the accuracy of the proposed analysis method and the feasibility of the control strategy.

  4. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-06-01

    Full Text Available The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  5. Parabolized Stability Equations analysis of nonlinear interactions with forced eigenmodes to control subsonic jet instabilities

    International Nuclear Information System (INIS)

    Itasse, Maxime; Brazier, Jean-Philippe; Léon, Olivier; Casalis, Grégoire

    2015-01-01

    Nonlinear evolution of disturbances in an axisymmetric, high subsonic, high Reynolds number hot jet with forced eigenmodes is studied using the Parabolized Stability Equations (PSE) approach to understand how modes interact with one another. Both frequency and azimuthal harmonic interactions are analyzed by setting up one or two modes at higher initial amplitudes and various phases. While single mode excitation leads to harmonic growth and jet noise amplification, controlling the evolution of a specific mode has been made possible by forcing two modes (m 1 , n 1 ), (m 2 , n 2 ), such that the difference in azimuth and in frequency matches the desired “target” mode (m 1 − m 2 , n 1 − n 2 ). A careful setup of the initial amplitudes and phases of the forced modes, defined as the “killer” modes, has allowed the minimizing of the initially dominant instability in the near pressure field, as well as its estimated radiated noise with a 15 dB loss. Although an increase of the overall sound pressure has been found in the range of azimuth and frequency analyzed, the present paper reveals the possibility to make the initially dominant instability ineffective acoustically using nonlinear interactions with forced eigenmodes

  6. A moving control volume method for smooth computation of hydrodynamic forces and torques on immersed bodies

    Science.gov (United States)

    Nangia, Nishant; Patankar, Neelesh A.; Bhalla, Amneet P. S.

    2017-11-01

    Fictitious domain methods for simulating fluid-structure interaction (FSI) have been gaining popularity in the past few decades because of their robustness in handling arbitrarily moving bodies. Often the transient net hydrodynamic forces and torques on the body are desired quantities for these types of simulations. In past studies using immersed boundary (IB) methods, force measurements are contaminated with spurious oscillations due to evaluation of possibly discontinuous spatial velocity of pressure gradients within or on the surface of the body. Based on an application of the Reynolds transport theorem, we present a moving control volume (CV) approach to computing the net forces and torques on a moving body immersed in a fluid. The approach is shown to be accurate for a wide array of FSI problems, including flow past stationary and moving objects, Stokes flow, and high Reynolds number free-swimming. The approach only requires far-field (smooth) velocity and pressure information, thereby suppressing spurious force oscillations and eliminating the need for any filtering. The proposed moving CV method is not limited to a specific IB method and is straightforward to implement within an existing parallel FSI simulation software. This work is supported by NSF (Award Numbers SI2-SSI-1450374, SI2-SSI-1450327, and DGE-1324585), the US Department of Energy, Office of Science, ASCR (Award Number DE-AC02-05CH11231), and NIH (Award Number HL117163).

  7. Enhancing the control of force in putting by video game training.

    Science.gov (United States)

    Fery, Y A; Ponserre, S

    2001-10-10

    Even if golf video games provide no proprioceptive afferences on actual putting movement, they may give sufficient substitutive visual cues to enhance force control in this skill. It was hypothesized that this usefulness requires, however, two conditions: the video game must provide reliable demonstrations of actual putts, and the user must want to use the game to make progress in actual putting. Accordingly, a video game was selected on the basis of its fidelity to the real-world game. It allowed two different methods of adjusting the virtual player's putting force in order to hole a putt: an analogue method that consisted of focusing on the virtual player's movement and a symbolic method that consisted of focusing on the movement of a gauge on a scale representing the virtual player's putting force. The participants had to use one of these methods with either the intention of making progress in actual putting or in a second condition to simply enjoy the game. Results showed a positive transfer of video playing to actual putting skill for the learning group and also, to a lesser degree, for the enjoyment group; but only when they used the symbolic method. Results are discussed in the context of how vision may convey force cues in sports video games.

  8. A positional code and anisotropic forces control tissue remodeling in Drosophila

    Science.gov (United States)

    Zallen, Jennifer

    A major challenge in developmental biology is to understand how tissue-scale changes in organism structure arise from events that occur on a cellular and molecular level. We are using cell biological, biophysical, and quantitative live-embryo imaging approaches to understand how genes encode the forces that shape tissues, and to identify the mechanisms that modulate cell behavior in response to local forces. In many animals, the elongated head-to-tail body axis is achieved by rapid and coordinated movements of hundreds of cells. We found that in the fruit fly, these cell movements are regulated by subcellular asymmetries in the localization of proteins that generate contractile and adhesive forces between cells. Asymmetries in the force-generating machinery are in turn controlled by a positional code of spatial information provided by an ancient family of Toll-related receptors that are widely used for pathogen recognition by the innate immune system. I will describe how this spatial system systematically orients local cell movements and collective rosette-like clusters in the Drosophila embryo. Rosettes have now also been shown to shape the body axis in chicks, frogs, and mice, demonstrating that rosette behaviors are a general mechanism linking cellular asymmetry to tissue reorganization.

  9. Parabolized Stability Equations analysis of nonlinear interactions with forced eigenmodes to control subsonic jet instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Itasse, Maxime, E-mail: Maxime.Itasse@onera.fr; Brazier, Jean-Philippe, E-mail: Jean-Philippe.Brazier@onera.fr; Léon, Olivier, E-mail: Olivier.Leon@onera.fr; Casalis, Grégoire, E-mail: Gregoire.Casalis@onera.fr [Onera - The French Aerospace Lab, F-31055 Toulouse (France)

    2015-08-15

    Nonlinear evolution of disturbances in an axisymmetric, high subsonic, high Reynolds number hot jet with forced eigenmodes is studied using the Parabolized Stability Equations (PSE) approach to understand how modes interact with one another. Both frequency and azimuthal harmonic interactions are analyzed by setting up one or two modes at higher initial amplitudes and various phases. While single mode excitation leads to harmonic growth and jet noise amplification, controlling the evolution of a specific mode has been made possible by forcing two modes (m{sub 1}, n{sub 1}), (m{sub 2}, n{sub 2}), such that the difference in azimuth and in frequency matches the desired “target” mode (m{sub 1} − m{sub 2}, n{sub 1} − n{sub 2}). A careful setup of the initial amplitudes and phases of the forced modes, defined as the “killer” modes, has allowed the minimizing of the initially dominant instability in the near pressure field, as well as its estimated radiated noise with a 15 dB loss. Although an increase of the overall sound pressure has been found in the range of azimuth and frequency analyzed, the present paper reveals the possibility to make the initially dominant instability ineffective acoustically using nonlinear interactions with forced eigenmodes.

  10. Feedback control and adaptive synchronization of chaotic forced Bonhoeffer-van der Pol oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Kontchou, E W Chimi; Fotsin, H B [Laboratoire d' Electronique, Departement de Physique, Faculte des Sciences, Universite de Dschang, B P 67 Dschang (Cameroon); Woafo, P [Laboratory of Modelling and Simulation in Engineering and Biological Physics, Faculty of Science, University of Yaounde I, Box 812, Yaounde (Cameroon)], E-mail: hbfotsin@yahoo.fr

    2008-04-15

    This paper deals with chaos control and synchronization in forced Bonhoeffer-van der Pol (FBVP) oscillators. The state equations of the model are first established and the stability is analysed. A feedback control strategy for stabilizing the chaotic dynamics on a periodic orbit of the phase space is investigated. Adaptive synchronization of two FBVP oscillators, based on parameter estimation and a nonlinear observer approach, is also investigated. It appears that a particular unknown parameter of the model can be estimated, which gives the possibility of recovering information through chaotic masking. An application in secure communications is presented.

  11. Feedback control and adaptive synchronization of chaotic forced Bonhoeffer-van der Pol oscillators

    International Nuclear Information System (INIS)

    Kontchou, E W Chimi; Fotsin, H B; Woafo, P

    2008-01-01

    This paper deals with chaos control and synchronization in forced Bonhoeffer-van der Pol (FBVP) oscillators. The state equations of the model are first established and the stability is analysed. A feedback control strategy for stabilizing the chaotic dynamics on a periodic orbit of the phase space is investigated. Adaptive synchronization of two FBVP oscillators, based on parameter estimation and a nonlinear observer approach, is also investigated. It appears that a particular unknown parameter of the model can be estimated, which gives the possibility of recovering information through chaotic masking. An application in secure communications is presented

  12. Comparative Effects of Different Balance-Training–Progression Styles on Postural Control and Ankle Force Production: A Randomized Controlled Trial

    Science.gov (United States)

    Cuğ, Mutlu; Duncan, Ashley; Wikstrom, Erik

    2016-01-01

    Context:  Despite the effectiveness of balance training, the exact parameters needed to maximize the benefits of such programs remain unknown. One such factor is how individuals should progress to higher levels of task difficulty within a balance-training program. Yet no investigators have directly compared different balance-training–progression styles. Objective:  To compare an error-based progression (ie, advance when proficient at a task) with a repetition-based progression (ie, advance after a set amount of repetitions) style during a balance-training program in healthy individuals. Design:  Randomized controlled trial. Setting:  Research laboratory. Patients or Other Participants:  A total of 28 (16 women, 12 men) physically healthy young adults (age = 21.57 ± 3.95 years, height = 171.60 ± 11.03 cm, weight = 72.96 ± 16.18 kg, body mass index = 24.53 ± 3.7). Intervention(s):  All participants completed 12 supervised balance-training sessions over 4 weeks. Each session consisted of a combination of dynamic unstable-surface tasks that incorporated a BOSU ball and lasted about 30 minutes. Main Outcome Measure(s):  Static balance from an instrumented force plate, dynamic balance as measured via the Star Excursion Balance Test, and ankle force production in all 4 cardinal planes of motion as measured with a handheld dynamometer before and after the intervention. Results:  Selected static postural-control outcomes, dynamic postural control, and ankle force production in all planes of motion improved (P .05) for any of the outcome measures. Conclusions:  A 4-week balance-training program consisting of dynamic unstable-surface exercises on a BOSU ball improved dynamic postural control and ankle force production in healthy young adults. These results suggest that an error-based balance-training program is comparable with but not superior to a repetition-based balance-training program in improving postural control and ankle force production in

  13. Forced-Air Warming Provides Better Control of Body Temperature in Porcine Surgical Patients

    Directory of Open Access Journals (Sweden)

    Brian T. Dent

    2016-09-01

    Full Text Available Background: Maintaining normothermia during porcine surgery is critical in ensuring subject welfare and recovery, reducing the risk of immune system compromise and surgical-site infection that can result from hypothermia. In humans, various methods of patient heating have been demonstrated to be useful, but less evaluation has been performed in techniques to prevent hypothermia perioperatively in pigs. Methods: We compared body temperature regulation during surgery before and after modification of the ambient temperature of the operating laboratories. Three different methods of heating were then compared; a standard circulating water mattress, a resistive fabric blanket, and a forced hot air system. The primary measure was percentage of temperature readings outside a specification range of 36.7–40.0 °C. Results: Tighter control of the ambient temperature while using a circulating water mattress reduced the occurrence of out-of-specification body temperature readings from 20.8% to 5.0%, with most of these the result of hypothermia. Use of a resistive fabric blanket further reduced out-of-specification readings to 1.5%, with a slight increase in the occurrence of hyperthermia. Use of a forced air system reduced out-of-specification readings to less 0.1%. Conclusions: Maintenance of normothermia perioperatively in pig can be improved by tightly controlling ambient temperatures. Use of a resistive blanket or a forced air system can lead to better control than a circulating water mattress, with the forced air system providing a faster response to temperature variations and less chance of hyperthermia.

  14. Real-time changes in corticospinal excitability related to motor imagery of a force control task.

    Science.gov (United States)

    Tatemoto, Tsuyoshi; Tsuchiya, Junko; Numata, Atsuki; Osawa, Ryuji; Yamaguchi, Tomofumi; Tanabe, Shigeo; Kondo, Kunitsugu; Otaka, Yohei; Sugawara, Kenichi

    2017-09-29

    To investigate real-time excitability changes in corticospinal pathways related to motor imagery in a changing force control task, using transcranial magnetic stimulation (TMS). Ten healthy volunteers learnt to control the contractile force of isometric right wrist dorsiflexion in order to track an on-screen sine wave form. Participants performed the trained task 40 times with actual muscle contraction in order to construct the motor image. They were then instructed to execute the task without actual muscle contraction, but by imagining contraction of the right wrist in dorsiflexion. Motor evoked potentials (MEPs), induced by TMS in the right extensor carpi radialis muscle (ECR) and flexor carpi radialis muscle (FCR), were measured during motor imagery. MEPs were induced at five time points: prior to imagery, during the gradual generation of the imaged wrist dorsiflexion (Increasing phase), the peak value of the sine wave, during the gradual reduction (Decreasing phase), and after completion of the task. The MEP ratio, as the ratio of imaged MEPs to resting-state, was compared between pre- and post-training at each time point. In the ECR muscle, the MEP ratio significantly increased during the Increasing phase and at the peak force of dorsiflexion imagery after training. Moreover, the MEP ratio was significantly greater in the Increasing phase than in the Decreasing phase. In the FCR, there were no significant consistent changes. Corticospinal excitability during motor imagery in an isometric contraction task was modulated in relation to the phase of force control after image construction. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Force to Rebalance Control of HRG and Suppression of Its Errors on the Basis of FPGA

    Directory of Open Access Journals (Sweden)

    Qingan Jiang

    2011-12-01

    Full Text Available A novel design of force to rebalance control for a hemispherical resonator gyro (HRG based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability.

  16. Force to rebalance control of HRG and suppression of its errors on the basis of FPGA.

    Science.gov (United States)

    Wang, Xu; Wu, Wenqi; Luo, Bing; Fang, Zhen; Li, Yun; Jiang, Qingan

    2011-01-01

    A novel design of force to rebalance control for a hemispherical resonator gyro (HRG) based on FPGA is demonstrated in this paper. The proposed design takes advantage of the automatic gain control loop and phase lock loop configuration in the drive mode while making full use of the quadrature control loop and rebalance control loop in controlling the oscillating dynamics in the sense mode. First, the math model of HRG with inhomogeneous damping and frequency split is theoretically analyzed. In addition, the major drift mechanisms in the HRG are described and the methods that can suppress the gyro drift are mentioned. Based on the math model and drift mechanisms suppression method, four control loops are employed to realize the manipulation of the HRG by using a FPGA circuit. The reference-phase loop and amplitude control loop are used to maintain the vibration of primary mode at its natural frequency with constant amplitude. The frequency split is readily eliminated by the quadrature loop with a DC voltage feedback from the quadrature component of the node. The secondary mode response to the angle rate input is nullified by the rebalance control loop. In order to validate the effect of the digital control of HRG, experiments are carried out with a turntable. The experimental results show that the design is suitable for the control of HRG which has good linearity scale factor and bias stability.

  17. Nonlinear adaptive robust back stepping force control of hydraulic load simulator: Theory and experiments

    International Nuclear Information System (INIS)

    Yao, Jianyong; Jiao, Zongxia; Yao, Bin

    2014-01-01

    High performance robust force control of hydraulic load simulator with constant but unknown hydraulic parameters is considered. In contrast to the linear control based on hydraulic linearization equations, hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative (PID) control not yield to high performance requirements. Furthermore, the hydraulic system may be subjected to non-smooth and discontinuous nonlinearities due to the directional change of valve opening. In this paper, based on a nonlinear system model of hydraulic load simulator, a discontinuous projection-based nonlinear adaptive robust back stepping controller is developed with servo valve dynamics. The proposed controller constructs a novel stable adaptive controller and adaptation laws with additional pressure dynamic related unknown parameters, which can compensate for the system nonlinearities and uncertain parameters, meanwhile a well-designed robust controller is also synthesized to dominate the model uncertainties coming from both parametric uncertainties and uncertain nonlinearities including unmodeled and ignored system dynamics. The controller theoretically guarantee a prescribed transient performance and final tracking accuracy in presence of both parametric uncertainties and uncertain nonlinearities; while achieving asymptotic output tracking in the absence of unstructured uncertainties. The implementation issues are also discussed for controller simplification. Some comparative results are obtained to verify the high-performance nature of the proposed controller.

  18. Nonlinear adaptive robust back stepping force control of hydraulic load simulator: Theory and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Jianyong [Nanjing University of Science and Technology, Nanjing (China); Jiao, Zongxia [Beihang University, Beijing (China); Yao, Bin [Purdue University, West Lafayette (United States)

    2014-04-15

    High performance robust force control of hydraulic load simulator with constant but unknown hydraulic parameters is considered. In contrast to the linear control based on hydraulic linearization equations, hydraulic inherent nonlinear properties and uncertainties make the conventional feedback proportional-integral-derivative (PID) control not yield to high performance requirements. Furthermore, the hydraulic system may be subjected to non-smooth and discontinuous nonlinearities due to the directional change of valve opening. In this paper, based on a nonlinear system model of hydraulic load simulator, a discontinuous projection-based nonlinear adaptive robust back stepping controller is developed with servo valve dynamics. The proposed controller constructs a novel stable adaptive controller and adaptation laws with additional pressure dynamic related unknown parameters, which can compensate for the system nonlinearities and uncertain parameters, meanwhile a well-designed robust controller is also synthesized to dominate the model uncertainties coming from both parametric uncertainties and uncertain nonlinearities including unmodeled and ignored system dynamics. The controller theoretically guarantee a prescribed transient performance and final tracking accuracy in presence of both parametric uncertainties and uncertain nonlinearities; while achieving asymptotic output tracking in the absence of unstructured uncertainties. The implementation issues are also discussed for controller simplification. Some comparative results are obtained to verify the high-performance nature of the proposed controller.

  19. Comparative study of millennials' (age 20-34 years) grip and lateral pinch with the norms.

    Science.gov (United States)

    Fain, Elizabeth; Weatherford, Cara

    Cross-sectional research design. Clinical practice continues to use normative data for grip and pinch measurements that were established in 1985. There is no updated norms despite different hand usage patterns in today's society. Measuring and comparing grip and pinch strengths with normative data is a valid method to determine hand function. This research was implemented to compare the grip and pinch measurements obtained from healthy millennials to the established norms and to describe hand usage patterns for millennials. Grip and lateral pinch measurements were obtained from a sample of 237 healthy millennials (ages 20-34 years). Strength scores were statistically lower that older normative data in all millennial grip strengths, with the exception of the women in the age group of 30-34 years. Specifically, this statistically significant trend was observed in all male grip strengths, as well as in women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). However, the lateral pinch data reflected was similar to the older norms with variances of 0.5-1 kg. Current data reflect statistically significant differences from the norms for all male grip measurements, as well as for women in the age group of 20-24 years (bilateral grip) and 25-29 years (right grip). No statistical significance was observed in the independent-sample t tests for the lateral pinch in men of all age groups. Statistical significance was noted for lateral pinch for female age groups for the left hand (20-24 years) and for bilateral lateral pinches (30-34 years). IV. Copyright © 2016 Hanley & Belfus. Published by Elsevier Inc. All rights reserved.

  20. Force Modeling, Identification, and Feedback Control of Robot-Assisted Needle Insertion: A Survey of the Literature

    Directory of Open Access Journals (Sweden)

    Chongjun Yang

    2018-02-01

    Full Text Available Robot-assisted surgery is of growing interest in the surgical and engineering communities. The use of robots allows surgery to be performed with precision using smaller instruments and incisions, resulting in shorter healing times. However, using current technology, an operator cannot directly feel the operation because the surgeon-instrument and instrument-tissue interaction force feedbacks are lost during needle insertion. Advancements in force feedback and control not only help reduce tissue deformation and needle deflection but also provide the surgeon with better control over the surgical instruments. The goal of this review is to summarize the key components surrounding the force feedback and control during robot-assisted needle insertion. The literature search was conducted during the middle months of 2017 using mainstream academic search engines with a combination of keywords relevant to the field. In total, 166 articles with valuable contents were analyzed and grouped into five related topics. This survey systemically summarizes the state-of-the-art force control technologies for robot-assisted needle insertion, such as force modeling, measurement, the factors that influence the interaction force, parameter identification, and force control algorithms. All studies show force control is still at its initial stage. The influence factors, needle deflection or planning remain open for investigation in future.

  1. Force Modeling, Identification, and Feedback Control of Robot-Assisted Needle Insertion: A Survey of the Literature.

    Science.gov (United States)

    Yang, Chongjun; Xie, Yu; Liu, Shuang; Sun, Dong

    2018-02-12

    Robot-assisted surgery is of growing interest in the surgical and engineering communities. The use of robots allows surgery to be performed with precision using smaller instruments and incisions, resulting in shorter healing times. However, using current technology, an operator cannot directly feel the operation because the surgeon-instrument and instrument-tissue interaction force feedbacks are lost during needle insertion. Advancements in force feedback and control not only help reduce tissue deformation and needle deflection but also provide the surgeon with better control over the surgical instruments. The goal of this review is to summarize the key components surrounding the force feedback and control during robot-assisted needle insertion. The literature search was conducted during the middle months of 2017 using mainstream academic search engines with a combination of keywords relevant to the field. In total, 166 articles with valuable contents were analyzed and grouped into five related topics. This survey systemically summarizes the state-of-the-art force control technologies for robot-assisted needle insertion, such as force modeling, measurement, the factors that influence the interaction force, parameter identification, and force control algorithms. All studies show force control is still at its initial stage. The influence factors, needle deflection or planning remain open for investigation in future.

  2. Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gaponenko, I., E-mail: iaroslav.gaponenko@unige.ch; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P. [DQMP, University of Geneva, 24 Quai E. Ansermet, 1211 Geneva 4 (Switzerland)

    2016-06-15

    We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

  3. Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

    Science.gov (United States)

    Gaponenko, I.; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P.

    2016-06-01

    We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

  4. Low-noise humidity controller for imaging water mediated processes in atomic force microscopy

    International Nuclear Information System (INIS)

    Gaponenko, I.; Gamperle, L.; Herberg, K.; Muller, S. C.; Paruch, P.

    2016-01-01

    We demonstrate the construction of a novel low-noise continuous flow humidity controller and its integration with a commercial variable-temperature atomic force microscope fluid cell, allowing precise control of humidity and temperature at the sample during nanoscale measurements. Based on wet and dry gas mixing, the design allows a high mechanical stability to be achieved by means of an ultrasonic atomiser for the generation of water-saturated gas, improving upon previous bubbler-based architectures. Water content in the flow is measured both at the inflow and outflow of the fluid cell, enabling the monitoring of water condensation and icing, and allowing controlled variation of the sample temperature independently of the humidity. To benchmark the performance of the controller, the results of detailed noise studies and time-based imaging of the formation of ice layers on highly oriented pyrolytic graphite are shown.

  5. Vortexlet models of flapping flexible wings show tuning for force production and control

    International Nuclear Information System (INIS)

    Mountcastle, A M; Daniel, T L

    2010-01-01

    Insect wings are compliant structures that experience deformations during flight. Such deformations have recently been shown to substantially affect induced flows, with appreciable consequences to flight forces. However, there are open questions related to the aerodynamic mechanisms underlying the performance benefits of wing deformation, as well as the extent to which such deformations are determined by the boundary conditions governing wing actuation together with mechanical properties of the wing itself. Here we explore aerodynamic performance parameters of compliant wings under periodic oscillations, subject to changes in phase between wing elevation and pitch, and magnitude and spatial pattern of wing flexural stiffness. We use a combination of computational structural mechanics models and a 2D computational fluid dynamics approach to ask how aerodynamic force production and control potential are affected by pitch/elevation phase and variations in wing flexural stiffness. Our results show that lift and thrust forces are highly sensitive to flexural stiffness distributions, with performance optima that lie in different phase regions. These results suggest a control strategy for both flying animals and engineering applications of micro-air vehicles.

  6. Evaluating Statistical Process Control (SPC) techniques and computing the uncertainty of force calibrations

    Science.gov (United States)

    Navard, Sharon E.

    1989-01-01

    In recent years there has been a push within NASA to use statistical techniques to improve the quality of production. Two areas where statistics are used are in establishing product and process quality control of flight hardware and in evaluating the uncertainty of calibration of instruments. The Flight Systems Quality Engineering branch is responsible for developing and assuring the quality of all flight hardware; the statistical process control methods employed are reviewed and evaluated. The Measurement Standards and Calibration Laboratory performs the calibration of all instruments used on-site at JSC as well as those used by all off-site contractors. These calibrations must be performed in such a way as to be traceable to national standards maintained by the National Institute of Standards and Technology, and they must meet a four-to-one ratio of the instrument specifications to calibrating standard uncertainty. In some instances this ratio is not met, and in these cases it is desirable to compute the exact uncertainty of the calibration and determine ways of reducing it. A particular example where this problem is encountered is with a machine which does automatic calibrations of force. The process of force calibration using the United Force Machine is described in detail. The sources of error are identified and quantified when possible. Suggestions for improvement are made.

  7. Balancing the intermolecular forces in peptide amphiphiles for controlling self-assembly transitions.

    Science.gov (United States)

    Buettner, C J; Wallace, A J; Ok, S; Manos, A A; Nicholl, M J; Ghosh, A; Tweedle, M F; Goldberger, J E

    2017-06-21

    While the influence of alkyl chain length and headgroup size on self-assembly behaviour has been well-established for simple surfactants, the rational control over the pH- and concentration-dependent self-assembly behaviour in stimuli responsive peptides remains an elusive goal. Here, we show that different amphiphilic peptides can have similar self-assembly phase diagrams, providing the relative strengths of the attractive and repulsive forces are balanced. Using palmitoyl-YYAAEEEEK(DO3A:Gd)-NH 2 and palmitoyl-YAAEEEEK(DO3A:Gd)-NH 2 as controls, we show that reducing hydrophobic attractive forces through fewer methylene groups in the alkyl chain will lead to a similar self-assembly phase diagram as increasing the electrostatic repulsive forces via the addition of a glutamic acid residue. These changes allow creation of self-assembled MRI vehicles with slightly different micelle and nanofiber diameters but with minimal changes in the spin-lattice T 1 relaxivity. These findings reveal a powerful strategy to design self-assembled vehicles with different sizes but with similar self-assembly profiles.

  8. Kriging modeling and SPSA adjusting PID with KPWF compensator control of IPMC gripper for mm-sized objects

    Science.gov (United States)

    Chen, Yang; Hao, Lina; Yang, Hui; Gao, Jinhai

    2017-12-01

    Ionic polymer metal composite (IPMC) as a new smart material has been widely concerned in the micromanipulation field. In this paper, a novel two-finger gripper which contains an IPMC actuator and an ultrasensitive force sensor is proposed and fabricated. The IPMC as one finger of the gripper for mm-sized objects can achieve gripping and releasing motion, and the other finger works not only as a support finger but also as a force sensor. Because of the feedback signal of the force sensor, this integrated actuating and sensing gripper can complete gripping miniature objects in millimeter scale. The Kriging model is used to describe nonlinear characteristics of the IPMC for the first time, and then the control scheme called simultaneous perturbation stochastic approximation adjusting a proportion integration differentiation parameter controller with a Kriging predictor wavelet filter compensator is applied to track the gripping force of the gripper. The high precision force tracking in the foam ball manipulation process is obtained on a semi-physical experimental platform, which demonstrates that this gripper for mm-sized objects can work well in manipulation applications.

  9. Motor Unit Number Estimate and Isometric Hand Grip Strength in Military Veterans with or Without Muscular Complaints: Reference Values for Longitudinal Follow-up.

    Science.gov (United States)

    Li, Mian; Yao, Wenguo; Sundahl, Cynthia

    2018-03-26

    It remains unclear if Gulf War (GW) veterans have a higher risk of developing motor neuron disorder. We intended to establish baseline neurophysiological values, including thenar motor unit number estimate (MUNE) and isometric hand grip (IHG) strength, to compare future follow-ups of deployed GW veterans with or without muscular complaints. We evaluated 19 GW veterans with self-reported weakness, cramps, or excessive muscle fatigue (Ill-19) and compared them with 18 controls without such muscular complaints (C-18). We performed MUNE on hand thenar muscles using adapted multipoint stimulation method for Ill-19 and 15 controls (C-15). We measured IHG strength (maximum force, endurance, and fatigue level) on Ill-19 and C-18 with a hand dynamometer. We performed nerve conduction studies on all study participants to determine which subjects had mild carpal tunnel syndrome (CTS). We compared the MUNE and IHG strength measures between Ill group and controls and between those with CTS and those without CTS. We obtained thenar MUNE of Ill-19 (95% CI of mean: 143-215; mean age: 46 yr) and compared it with that of C-15 (95% CI of mean: 161-230; mean age: 45 yr), and 95% of CI of mean among IHG strength variables (maximum force: 324-381 Newton; endurance: 32-42 s; fatigue level: 24%-33%) compared with C-18 (maximum force: 349-408 Newton; endurance: 35-46 s; fatigue level: 21%-27%). There was no significant difference in either MUNE or IHG strength between Ill-19 group and controls. The MUNE and IHG maximum forces were significantly lower in those with CTS compared with those without CTS. As a surrogate of mild CTS, the median versus ulnar distal sensory latency on nerve conduction study was only weakly associated with MUNE, maximum force, and fatigue level, respectively. To our knowledge, no published study on MUNE reference values of military veteran population has been available. The quantifiable values of both thenar MUNE and IHG strength of military veterans serve as

  10. Effective method to control the levitation force and levitation height in a superconducting maglev system

    Science.gov (United States)

    Yang, Peng-Tao; Yang, Wan-Min; Wang, Miao; Li, Jia-Wei; Guo, Yu-Xia

    2015-11-01

    The influence of the width of the middle magnet in the permanent magnet guideways (PMGs) on the levitation force and the levitation height of single-domain yttrium barium copper oxide (YBCO) bulks has been investigated at 77 K under the zero field cooled (ZFC) state. It is found that the largest levitation force can be obtained in the system with the width of the middle magnet of the PMG equal to the size of the YBCO bulk when the gap between the YBCO bulk and PMG is small. Both larger levitation force and higher levitation height can be obtained in the system with the width of the middle magnet of the PMG larger than the size of the YBCO bulk. The stiffness of the levitation force between the PMG and the YBCO bulk is higher in the system with a smaller width of the middle magnet in the PMG. These results provide an effective way to control the levitation force and the levitation height for the superconducting maglev design and applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 51342001 and 50872079), the Key-grant Project of Chinese Ministry of Education (Grant No. 311033), the Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20120202110003), the Innovation Team in Shaanxi Province, China (Grant No. 2014KTC-18), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. GK201101001 and GK201305014), and the Outstanding Doctoral Thesis Foundation Project of Shaanxi Normal University, China (Grant Nos. X2011YB08 and X2012YB05).

  11. A feedback control system for vibration of magnetostrictive plate subjected to follower force using sinusoidal shear

    Directory of Open Access Journals (Sweden)

    A. Ghorbanpour Arani

    2016-03-01

    Full Text Available In this research, the vibrational behavior of magnetostrictive plate (MsP as a smart component is studied. The plate is subjected to an external follower force and a magnetic field in which the vibration response of MsP has been investigated for both loading combinations. The velocity feedback gain parameter is evaluated to study the effect of magnetic field which is generated by the coil. Sinusoidal shear deformation theory is utilized due to its accuracy of polynomial function with respect to other plate theories. Equations of motion are derived using Hamilton’s principle and solved by differential quadrature method (DQM considering general boundary conditions. The effects of aspect ratio, thickness ratio, follower force and velocity feedback gain are investigated on the frequency response of MsP. Results indicate that magneto-mechanical coupling in MsM helps to control vibrational behaviors of systems such as electro-hydraulic actuator, wireless linear Motors and sensors.

  12. Humans can integrate force feedback to toes in their sensorimotor control of a robotic hand.

    Science.gov (United States)

    Panarese, Alessandro; Edin, Benoni B; Vecchi, Fabrizio; Carrozza, Maria C; Johansson, Roland S

    2009-12-01

    Tactile sensory feedback is essential for dexterous object manipulation. Users of hand myoelectric prostheses without tactile feedback must depend essentially on vision to control their device. Indeed, improved tactile feedback is one of their main priorities. Previous research has provided evidence that conveying tactile feedback can improve prostheses control, although additional effort is required to solve problems related to pattern recognition learning, unpleasant sensations, sensory adaptation, and low spatiotemporal resolution. Still, these studies have mainly focused on providing stimulation to hairy skin regions close to the amputation site, i.e., usually to the upper arm. Here, we explored the possibility to provide tactile feedback to the glabrous skin of toes, which have mechanical and neurophysiological properties similar to the fingertips. We explored this paradigm in a grasp-and-lift task, in which healthy participants controlled two opposing digits of a robotic hand by changing the spacing of their index finger and thumb. The normal forces applied by the robotic fingertips to a test object were fed back to the right big and second toe. We show that within a few lifting trials, all the participants incorporated the force feedback received by the foot in their sensorimotor control of the robotic hand.

  13. Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control

    Directory of Open Access Journals (Sweden)

    Luis Botaya

    2016-05-01

    Full Text Available Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current–voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips.

  14. a Method for Preview Vibration Control of Systems Having Forcing Inputs and Rapidly-Switched Dampers

    Science.gov (United States)

    ElBeheiry, E. M.

    1998-07-01

    In a variety of applications, especially in large scale dynamic systems, the mechanization of different vibration control elements in different locations would be decided by limitations placed on the modal vibration of the system and the inherent dynamic coupling between its modes. Also, the quality of vibration control to the economy of producing the whole system would be another trade-off leading to a mix of passive, active and semi-active vibration control elements in one system. This termactiveis limited to externally powered vibration control inputs and the termsemi-activeis limited to rapidly switched dampers. In this article, an optimal preview control method is developed for application to dynamic systems having active and semi-active vibration control elements mechanized at different locations in one system. The system is then a piecewise (bilinear) controller in which two independent sets of control inputs appear additively and multiplicatively. Calculus of variations along with the Hamiltonian approach are employed for the derivation of this method. In essence, it requires the active elements to be ideal force generators and the switched dampers to have the property of on-line variation of the damping characteristics to pre-determined limits. As the dampers switch during operation the whole system's structure differs, and then values of the active forcing inputs are adapted to match these rapid changes. Strictly speaking, each rapidly switched damper has pre-known upper and lower damping levels and it can take on any in-between value. This in-between value is to be determined by the method as long as the damper tracks a pre-known fully active control demand. In every damping state of each semi-active damper the method provides the optimal matching values of the active forcing inputs. The method is shown to have the feature of solving simple standard matrix equations to obtain closed form solutions. A comprehensive 9-DOF tractor semi-trailer model is used

  15. A new orthodontic force system for moment control utilizing the flexibility of common wires: Evaluation of the effect of contractile force and hook length

    Directory of Open Access Journals (Sweden)

    Wei-Jen Lai

    2018-01-01

    Conclusion: The system acted similar to an off-center V-bend and can be applied in clinical practice as an unconventional loop design. We suggest that this force system has the potential for second-order moment control in clinical applications.

  16. 16 CFR Figure 5 to Part 1512 - Typical Handbrake Actuator Showing Grip Dimension

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Typical Handbrake Actuator Showing Grip Dimension 5 Figure 5 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Actuator Showing Grip Dimension EC03OC91.072 ...

  17. Is grip strength a predictor for total muscle strength in healthy children, adolescents, and young adults?

    NARCIS (Netherlands)

    Wind, Anne E.; Takken, Tim; Helders, Paul J. M.; Engelbert, Raoul H. H.

    2010-01-01

    The primary purpose of this study was to examine whether grip strength is related to total muscle strength in children, adolescents, and young adults. The second purpose was to provide reference charts for grip strength, which could be used in the clinical and research setting. This cross-sectional

  18. Mammographic compression after breast conserving therapy: Controlling pressure instead of force

    International Nuclear Information System (INIS)

    Groot, J. E. de; Branderhorst, W.; Grimbergen, C. A.; Broeders, M. J. M.; Heeten, G. J. den

    2014-01-01

    Purpose: X-ray mammography is the primary tool for early detection of breast cancer and for follow-up after breast conserving therapy (BCT). BCT-treated breasts are smaller, less elastic, and more sensitive to pain. Instead of the current force-controlled approach of applying the same force to each breast, pressure-controlled protocols aim to improve standardization in terms of physiology by taking breast contact area and inelasticity into account. The purpose of this study is to estimate the potential for pressure protocols to reduce discomfort and pain, particularly the number of severe pain complaints for BCT-treated breasts. Methods: A prospective observational study including 58 women having one BCT-treated breast and one untreated nonsymptomatic breast, following our hospital's 18 decanewton (daN) compression protocol was performed. Breast thickness, applied force, contact area, mean pressure, breast volume, and inelasticity (mean E-modulus) were statistically compared between the within-women breast pairs, and data were used as predictors for severe pain, i.e., scores 7 and higher on an 11-point Numerical Rating Scale. Curve-fitting models were used to estimate how pressure-controlled protocols affect breast thickness, compression force, and pain experience. Results: BCT-treated breasts had on average 27% smaller contact areas, 30% lower elasticity, and 30% higher pain scores than untreated breasts (allp 2 decrease in contact area, as well as increased pain sensitivity, BCT-breasts had on average 5.3 times higher odds for severe pain than untreated breasts. Model estimations for a pressure-controlled protocol with a 10 kPa target pressure, which is below normal arterial pressure, suggest an average 26% (range 10%–36%) reduction in pain score, and an average 77% (range 46%–95%) reduction of the odds for severe pain. The estimated increase in thickness is +6.4% for BCT breasts. Conclusions: After BCT, women have hardly any choice in avoiding an annual

  19. Passive hybrid force-position control for tele-operation based on real-time simulation of a virtual mechanism

    International Nuclear Information System (INIS)

    Joly, L.; Andriot, C.

    1995-01-01

    Hybrid force-position control aims at controlling position and force in separate directions. It is particularly useful to perform certain robotic tasks. In tele-operation context, passivity is important because it ensures stability when the system interacts with any passive environment. In this paper, we propose an original approach to hybrid force-position control of a force reflecting tele-robot system. It is based on real-time simulation of a virtual mechanism corresponding to the task. the resulting control law is passive. Experiments on a 6 degrees of freedom tele-operation system consisting in following a bent pipe under several control modes validate the approach. (authors). 12 refs., 6 figs

  20. Fuel assembly gripping device using self-locking mechanism

    International Nuclear Information System (INIS)

    Lee, G. M.; Choi, S.; Kim, K. S.; Kim, T. W.; Jeong, K. H.; Park, K. B.; Chang, M. H.

    1999-07-01

    This report presents an actuating principles and structure for two kind of the fuel assembly gripping devices (Gripper-A, B) developed for SMART. The main components of these grippers are push bundle, rotation bundle, upper guide tube and chuck assembly. The rope attached to winch system on moving cask hangs gripper's push bundle. Due to a down-and-up operation of winch system, the push bundle pushes crown teeth shaped rotation bundle and then it is pushed down and rotated counter clockwise. The push-and-pull sequential operation of push bundle makes the rotation bundle is pushed, rotated and returned, moreover it makes the chuck assembly is expanded or shrunk. The expansion and shrinkage motion of chuck assembly makes the gripper latch and release the fuel assembly. Gripper-A suits for the handling of the fuel assembly with square shaped latching hole. Otherwise Gripper-B suits for a circular shaped latching hole. (author). 5 refs., 20 figs

  1. NBL Pistol Grip Tool for Underwater Training of Astronauts

    Science.gov (United States)

    Liszka, Michael; Ashmore, Matthew; Behnke, Mark; Smith, Walter; Waterman, Tod

    2011-01-01

    A document discusses a lightweight, functional mockup of the Pistol Grip Tool for use during underwater astronaut training. Previous training tools have caused shoulder injuries. This new version is more than 50 percent lighter [in water, weight is 2.4 lb (=1.1 kg)], and can operate for a six-hour training session after 30 minutes of prep for submersion. Innovations in the design include the use of lightweight materials (aluminum and Delrin(Registered TradeMark)), creating a thinner housing, and the optimization of internal space with the removal of as much excess material as possible. This reduces tool weight and maximizes buoyancy. Another innovation for this tool is the application of a vacuum that seats the Orings in place and has shown to be reliable in allowing underwater usage for up to six hours.

  2. Effects of aging on control of timing and force of finger tapping.

    Science.gov (United States)

    Sasaki, Hirokazu; Masumoto, Junya; Inui, Nobuyuki

    2011-04-01

    The present study examined whether the elderly produced a hastened or delayed tap with a negative or positive constant intertap interval error more frequently in self-paced tapping than in the stimulus-synchronized tapping for the 2 N target force at 2 or 4 Hz frequency. The analysis showed that, at both frequencies, the percentage of the delayed tap was larger in the self-paced tapping than in the stimulus-synchronized tapping, whereas the hastened tap showed the opposite result. At the 4 Hz frequency, all age groups had more variable intertap intervals during the self-paced tapping than during the stimulus-synchronized tapping, and the variability of the intertap intervals increased with age. Thus, although the increase in the frequency of delayed taps and variable intertap intervals in the self-paced tapping perhaps resulted from a dysfunction of movement timing in the basal ganglia with age, the decline in timing accuracy was somewhat improved by an auditory cue. The force variability of tapping at 4 Hz further increased with age, indicating an effect of aging on the control of force.

  3. Radiative forcing associated with particulate carbon emissions resulting from the use of mercury control technology.

    Science.gov (United States)

    Lin, Guangxing; Penner, Joyce E; Clack, Herek L

    2014-09-02

    Injection of powdered activated carbon (PAC) adsorbents into the flue gas of coal fired power plants with electrostatic precipitators (ESPs) is the most mature technology to control mercury emissions for coal combustion. However, the PAC itself can penetrate ESPs to emit into the atmosphere. These emitted PACs have similar size and optical properties to submicron black carbon (BC) and thus could increase BC radiative forcing unintentionally. The present paper estimates, for the first time, the potential emission of PAC together with their climate forcing. The global average maximum potential emissions of PAC is 98.4 Gg/yr for the year 2030, arising from the assumed adoption of the maximum potential PAC injection technology, the minimum collection efficiency, and the maximum PAC injection rate. These emissions cause a global warming of 2.10 mW m(-2) at the top of atmosphere and a cooling of -2.96 mW m(-2) at the surface. This warming represents about 2% of the warming that is caused by BC from direct fossil fuel burning and 0.86% of the warming associated with CO2 emissions from coal burning in power plants. Its warming is 8 times more efficient than the emitted CO2 as measured by the 20-year-integrated radiative forcing per unit of carbon input (the 20-year Global Warming Potential).

  4. The Death of Democracy and the Forces of Power and Control: The Case of Europe

    Directory of Open Access Journals (Sweden)

    Theo Gavrielides

    2016-08-01

    Full Text Available At the time of writing, the United Kingdom is grabbling with its decision to abandon its European Union membership. As the country is divided and hate incidents are increased by almost 50%, this think-piece presents a critical analysis of Europe’s missed opportunity for social justice. The paper presents evidence by analysing the civil and political rights jurisprudence of the European Court of Human Rights in order to explore the potential of what it calls the “human rights project” for a regional democracy. The paper shows that a key objective of the European Convention of Human Rights was the development of case law that would construct a regional democracy for bringing consistency in the enjoyment of civil and political rights across the continent. This “human rights project” was well underway, but is now hampered by contemporary forces of power and control that are ridiculing the work and status of the Council of Europe. The paper identifies three levers that move these forces, namely: financial and security terror as well as nationalism. The paper warns that if these forces are not managed, the backlash in social justice will continue while the human rights project for a regional democracy will come to its demise.

  5. Comparative study of maximum isometric grip strength in different sports

    Directory of Open Access Journals (Sweden)

    Noé Gomes Borges Junior

    2009-01-01

    Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n3p292   The objective of this study was to compare maximum isometric grip strength (Fmaxbetween different sports and between the dominant (FmaxD and non-dominant (FmaxND hand. Twenty-nine male aikido (AI, jiujitsu (JJ, judo (JU and rowing (RO athletes and 21non-athletes (NA participated in the study. The hand strength test consisted of maintainingmaximum isometric grip strength for 10 seconds using a hand dynamometer. The position of the subjects was that suggested by the American Society of Hand Therapy. Factorial 2X5 ANOVA with Bonferroni correction, followed by a paired t test and Tukey test, was used for statistical analysis. The highest Fmax values were observed for the JJ group when using the dominant hand,followed by the JU, RO, AI and NA groups. Variation in Fmax could be attributed to handdominance (30.9%, sports modality (39.9% and the interaction between hand dominance andsport (21.3%. The present results demonstrated significant differences in Fmax between the JJ and AI groups and between the JJ and NA groups for both the dominant and non-dominant hand. Significant differences in Fmax between the dominant and non-dominant hand were only observed in the AI and NA groups. The results indicate that Fmax can be used for comparisonbetween different sports modalities, and to identify differences between the dominant and nondominanthand. Studies involving a larger number of subjects will permit the identification of differences between other modalities.

  6. Research on the Obstacle Negotiation Strategy for the Heavy-duty Six-legged Robot based on Force Control

    Directory of Open Access Journals (Sweden)

    Li Mantian

    2017-01-01

    Full Text Available To make heavy-duty six-legged robots without environment reconstruction system negotiate obstacles after the earthquake successfully, an obstacle negotiation strategy is described in this paper. The reflection strategy is generated by the information of plantar force sensors and Bezier Curve is used to plan trajectory. As the heavy-duty six-legged robot has a large inertia, force controller is necessary to ensure the robot not to lose stability while negotiating obstacles. Impedance control is applied to reduce the impact of collision and active force control is applied to adjust the pose of the robot. The robot can walk through zones that are filled with obstacles automatically because of force control. Finally, the algorithm is verified in a simulation environment.

  7. MASS TRANSFER CONTROL OF A BACKWARD-FACING STEP FLOW BY LOCAL FORCING- EFFECT OF REYNOLDS NUMBER

    Directory of Open Access Journals (Sweden)

    Zouhaier MEHREZ

    2011-01-01

    Full Text Available The control of fluid mechanics and mass transfer in separated and reattaching flow over a backward-facing step by a local forcing, is studied using Large Eddy Simulation (LES.To control the flow, the local forcing is realized by a sinusoidal oscillating jet at the step edge. The Reynolds number is varied in the range 10000 ≤ Re≤ 50000 and the Schmidt number is fixed at 1.The found results show that the flow structure is modified and the local mass transfer is enhanced by the applied forcing. The observed changes depend on the Reynolds number and vary with the frequency and amplitude of the local forcing. For the all Reynolds numbers, the largest recirculation zone size reduction is obtained at the optimum forcing frequency St = 0.25. At this frequency the local mass transfer enhancement attains the maximum.

  8. Stability Control of Force-Reflected Nonlinear Multilateral Teleoperation System under Time-Varying Delays

    Directory of Open Access Journals (Sweden)

    Da Sun

    2016-01-01

    Full Text Available A novel control algorithm based on the modified wave-variable controllers is proposed to achieve accurate position synchronization and reasonable force tracking of the nonlinear single-master-multiple-slave teleoperation system and simultaneously guarantee overall system’s stability in the presence of large time-varying delays. The system stability in different scenarios of human and environment situations has been analyzed. The proposed method is validated through experimental work based on the 3-DOF trilateral teleoperation system consisting of three different manipulators. The experimental results clearly demonstrate the feasibility of the proposed algorithm to achieve high transparency and robust stability in nonlinear single-master-multiple-slave teleoperation system in the presence of time-varying delays.

  9. Report of the Census Task Force on beamline control system requirements

    International Nuclear Information System (INIS)

    Barsotti, E.J.; Bartlett, J.F.; Bogert, V.D.; Borcherding, F.O.; Butler, J.; Czarapata, P.C.; Spalding, W.J.; Thomas, A.D.

    1986-01-01

    A special task force was appointed to study the experience with the present beamline control system at Fermilab and to make recommendations in this area. The charge of the committee and the list of its members are appended. In order to carry out its assignment, the committee conducted a series of meetings in which it discussed the controls situation in general and the best way to approach the user community. The various groups of users were identified, and a letter was written to representatives of these groups asking questions concerning the present system and future needs. The committee met with each group to discuss the response to these questions. Written summaries of the discussions are appended. Conclusions are drawn regarding current problems, systematic upgrades and specific recommendations

  10. Simulation of VDE under intervention of vertical stability control and vertical electromagnetic force on the ITER vacuum vessel

    International Nuclear Information System (INIS)

    Miyamoto, S.; Sugihara, M.; Shinya, K.; Nakamura, Y.; Toshimitsu, S.; Lukash, V.E.; Khayrutdinov, R.R.; Sugie, T.; Kusama, Y.; Yoshino, R.

    2012-01-01

    Highlights: ► Taking account of intervention of VS control, VDE simulations were carried out. ► Malfunctioning of VS circuit (positive feedback) enhances the vertical force. ► The worst case was explored for vertical force on the ITER vacuum vessel. ► We confirmed the force is still within the design margin even if the worst case. - Abstract: Vertical displacement events (VDEs) and disruptions usually take place under intervention of vertical stability (VS) control and the vertical electromagnetic force induced on vacuum vessels is potentially influenced. This paper presents assessment of the force that arises from the VS control in ITER VDEs using a numerical simulation code DINA. The focus is on a possible malfunctioning of the ex-vessel VS control circuit: radial magnetic field is unintentionally applied to the direction of enhancing the vertical displacement further. Since this type of failure usually causes the largest forces (or halo currents) observed in the present experiments, this situation must be properly accommodated in the design of the ITER vacuum vessel. DINA analysis shows that although the ex-vessel VS control modifies radial field, it does not affect plasma motion and current quench behavior including halo current generation because the vacuum vessel shields the field created by the ex-vessel coils. Nevertheless, the VS control modifies the force on the vessel by directly acting on the eddy current carried by the conducting structures of the vessel. Although the worst case was explored in a range of plasma inductance and pattern of VS control in combination with the in-vessel VS control circuit, the result confirmed that the force is still within the design margin.

  11. Report of the Material Control and Material Accounting Task Force: summary

    International Nuclear Information System (INIS)

    1978-03-01

    A special review was made of the safeguards maintained by licensees possessing 5 kg or more of strategic special nuclear material (SSNM), i.e., plutonium, uranium-233, or uranium enriched in the uranium-235 isotope to 20 percent or more. A Task Force was formed to define the roles and objectives of material control and material accounting in the NRC safeguards program; recommend goals for material control and material accounting systems based on their roles and objectives; assess the extent to which the existing regulatory base meets or provides the capability to meet the recommended goals; and to provide direction for material control and material accounting development, including both near-term and long-term upgrades. Based on results of Task Force investigations it is recommended that licensee plans for measurement control programs be submitted in response to Section 70.57(c) of Title 10 of the Code of Federal Regulations. Other recommendations include the review and upgrading, as necessary, of measurement error propagation models used by each licensee; revision of Nuclear Materials Management and Safeguards System (NMMSS) reporting entities for SSNM licensees to be consistent with the partitioning of facilities into plants or, if appropriate, accounting units; review of NMMSS reporting entities for SSNM licensees to assure that data for high enriched uranium operations are clearly separated from low enriched uranium operations; upgrading of the editing by NMMSS of reported licensee safeguards data for accuracy and consistency; and the acquisition of (a) a secure interactive computer capability for use in collecting, storing, sorting, and analyzing special nuclear material accounting data, and (b) associated flexible computer software that presents safeguards information in a succinct and comprehensive manner

  12. The force control and path planning of electromagnetic induction-based massage robot.

    Science.gov (United States)

    Wang, Wendong; Zhang, Lei; Li, Jinzhe; Yuan, Xiaoqing; Shi, Yikai; Jiang, Qinqin; He, Lijing

    2017-07-20

    Massage robot is considered as an effective physiological treatment to relieve fatigue, improve blood circulation, relax muscle tone, etc. The simple massage equipment quickly spread into market due to low cost, but they are not widely accepted due to restricted massage function. Complicated structure and high cost caused difficulties for developing multi-function massage equipment. This paper presents a novel massage robot which can achieve tapping, rolling, kneading and other massage operations, and proposes an improved reciprocating path planning algorithm to improve massage effect. The number of coil turns, the coil current and the distance between massage head and yoke were chosen to investigate the influence on massage force by finite element method. The control system model of the wheeled massage robot was established, including control subsystem of the motor, path algorithm control subsystem, parameter module of the massage robot and virtual reality interface module. The improved reciprocating path planning algorithm was proposed to improve regional coverage rate and massage effect. The influence caused by coil current, the number of coil turns and the distance between massage head and yoke were simulated in Maxwell. It indicated that coil current has more important influence compared to the other two factors. The path planning simulation of the massage robot was completed in Matlab, and the results show that the improved reciprocating path planning algorithm achieved higher coverage rate than the traditional algorithm. With the analysis of simulation results, it can be concluded that the number of coil turns and the distance between the moving iron core and the yoke could be determined prior to coil current, and the force can be controllable by optimizing structure parameters of massage head and adjusting coil current. Meanwhile, it demonstrates that the proposed algorithm could effectively improve path coverage rate during massage operations, therefore

  13. Optimization and Control for Sharing of the ITER Vacuum Vessel Support Force

    International Nuclear Information System (INIS)

    Rozov, V.

    2006-01-01

    The ITER Vacuum Vessel (VV) is a complex body supported in 9 points below lower ports by restraints in the radial, toroidal and vertical directions. The applied load produces a combination of reaction forces, which must be consistent with the design of the supported object. A reasonable sharing of the load among the supports is important for overall performance of the structure and helps to avoid excessive stress at the joints between the VV and lower ports. Optimization has been performed of the sharing of the total horizontal load applied to the ITER VV between radial and toroidal restraints. An effective method of finding simple parametric relationships between the design parameters of supports and the balance of the reaction forces has been developed. This allows purely analytical prediction of the sharing of the reaction forces for any desired stiffness of the applied restraints with no need for finite element structural analysis, and also allows control of the sharing by a proper selection of parameters of the supports. The method is based on the use of elementary mono-directional schemes - equivalent oscillators built for the main global modes, in static problems. The types of schemes and parameters of their members, related to the a-priori unknown stiffness of the VV structure under the supports, are found from consideration of the free vibration problem for the object using a 3D model of the VV with mass simulators - a series of simple eigenvalue analyses with variation of stiffness of the external restraints, that demands quite moderate computational resources. The equivalent schemes for the main modes not only enable simple one-line analytical calculation of the natural frequencies at any desired stiffness of the supports, but also indicate the contributions and balance of stiffness, to be considered in the static problem. The results of assessments of the reaction forces by direct static structural analyses for several cases are in agreement with values

  14. One-Channel Surface Electromyography Decomposition for Muscle Force Estimation

    Directory of Open Access Journals (Sweden)

    Wentao Sun

    2018-05-01

    Full Text Available Estimating muscle force by surface electromyography (sEMG is a non-invasive and flexible way to diagnose biomechanical diseases and control assistive devices such as prosthetic hands. To estimate muscle force using sEMG, a supervised method is commonly adopted. This requires simultaneous recording of sEMG signals and muscle force measured by additional devices to tune the variables involved. However, recording the muscle force of the lost limb of an amputee is challenging, and the supervised method has limitations in this regard. Although the unsupervised method does not require muscle force recording, it suffers from low accuracy due to a lack of reference data. To achieve accurate and easy estimation of muscle force by the unsupervised method, we propose a decomposition of one-channel sEMG signals into constituent motor unit action potentials (MUAPs in two steps: (1 learning an orthogonal basis of sEMG signals through reconstruction independent component analysis; (2 extracting spike-like MUAPs from the basis vectors. Nine healthy subjects were recruited to evaluate the accuracy of the proposed approach in estimating muscle force of the biceps brachii. The results demonstrated that the proposed approach based on decomposed MUAPs explains more than 80% of the muscle force variability recorded at an arbitrary force level, while the conventional amplitude-based approach explains only 62.3% of this variability. With the proposed approach, we were also able to achieve grip force control of a prosthetic hand, which is one of the most important clinical applications of the unsupervised method. Experiments on two trans-radial amputees indicated that the proposed approach improves the performance of the prosthetic hand in grasping everyday objects.

  15. Hand Grip Strength: age and gender stratified normative data in a population-based study

    Directory of Open Access Journals (Sweden)

    Taylor Anne W

    2011-04-01

    Full Text Available Abstract Background The North West Adelaide Health Study is a representative longitudinal cohort study of people originally aged 18 years and over. The aim of this study was to describe normative data for hand grip strength in a community-based Australian population. Secondary aims were to investigate the relationship between body mass index (BMI and hand grip strength, and to compare Australian data with international hand grip strength norms. Methods The sample was randomly selected and recruited by telephone interview. Overall, 3 206 (81% of those recruited participants returned to the clinic during the second stage (2004-2006 which specifically focused on the collection of information relating to musculoskeletal conditions. Results Following the exclusion of 435 participants who had hand pain and/or arthritis, 1366 men and 1312 women participants provided hand grip strength measurement. The study population was relatively young, with 41.5% under 40 years; and their mean BMI was 28.1 kg/m2 (SD 5.5. Higher hand grip strength was weakly related to higher BMI in adults under the age of 30 and over the age of 70, but inversely related to higher BMI between these ages. Australian norms from this sample had amongst the lowest of the hand grip strength of the internationally published norms, except those from underweight populations. Conclusions This population demonstrated higher BMI and lower grip strength in younger participants than much of the international published, population data. A complete exploration of the relationship between BMI and hand grip strength was not fully explored as there were very few participants with BMI in the underweight range. The age and gender grip strength values are lower in younger adults than those reported in international literature.

  16. Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles

    Science.gov (United States)

    Laine, Christopher M.; Valero-Cuevas, Francisco J.

    2018-01-01

    Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,‘common drive’), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary ‘isometric’ force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease. PMID:29309405

  17. Cardinal features of involuntary force variability can arise from the closed-loop control of viscoelastic afferented muscles.

    Science.gov (United States)

    Nagamori, Akira; Laine, Christopher M; Valero-Cuevas, Francisco J

    2018-01-01

    Involuntary force variability below 15 Hz arises from, and is influenced by, many factors including descending neural drive, proprioceptive feedback, and mechanical properties of muscles and tendons. However, their potential interactions that give rise to the well-structured spectrum of involuntary force variability are not well understood due to a lack of experimental techniques. Here, we investigated the generation, modulation, and interactions among different sources of force variability using a physiologically-grounded closed-loop simulation of an afferented muscle model. The closed-loop simulation included a musculotendon model, muscle spindle, Golgi tendon organ (GTO), and a tracking controller which enabled target-guided force tracking. We demonstrate that closed-loop control of an afferented musculotendon suffices to replicate and explain surprisingly many cardinal features of involuntary force variability. Specifically, we present 1) a potential origin of low-frequency force variability associated with co-modulation of motor unit firing rates (i.e.,'common drive'), 2) an in-depth characterization of how proprioceptive feedback pathways suffice to generate 5-12 Hz physiological tremor, and 3) evidence that modulation of those feedback pathways (i.e., presynaptic inhibition of Ia and Ib afferents, and spindle sensitivity via fusimotor drive) influence the full spectrum of force variability. These results highlight the previously underestimated importance of closed-loop neuromechanical interactions in explaining involuntary force variability during voluntary 'isometric' force control. Furthermore, these results provide the basis for a unifying theory that relates spinal circuitry to various manifestations of altered involuntary force variability in fatigue, aging and neurological disease.

  18. Combined Discrete Space Voltage Vector with Direct Torque Control for Bearingless Brushless DC Motor and Closed-Loop Suspended Force Control

    Directory of Open Access Journals (Sweden)

    Weiran Wang

    2013-06-01

    Full Text Available In order to improve the performance of bearingless brushless DC motor, a closed-loop suspended force controller combining the discrete space voltage vector modulation is applied and the direct torque control is presented in this paper. Firstly, we increase the number of the control vector to reduce the torque ripple. Then, the suspending equation is constructed which is spired by the direct torque control algorithm. As a result, the closed-loop suspended force controller is built. The simulated and experimental results evaluate the performance of the proposed method. The more advantage is that the proposed algorithm can achieve the fast torque response, reduce the torque ripple, and follow ideal stator flux track. Furthermore, the motor which implants the closed-loop suspended force controller cannot onlyobtain the dynamic response rapidly and displacement control accurately, but also has the characteristics of bearingless brushless DC motor (such as simple structure, high energy efficiency, small volume and low failure rate.

  19. Controlling the structure of forced convective flow by means of rotating magnetic-field inductors

    International Nuclear Information System (INIS)

    Sorkin, M.Z.; Mozgirs, O.Kh.

    1993-01-01

    The forced convective flow generated by a rotating magnetic-field inductor is used in a melt as a means of controlling the transfer of mass and heat in the case of directed crystallization. An obvious advantage in using a rotating field is the generation of azimuthal twisting of the fluid, this providing for an evening out of the crystallization conditions in the azimuthal direction under nonsymmetrical boundary conditions in an actual technological process. From the standpoint of affecting the crystallization processes it would be preferable to use an inductor which would allow alteration of the intensity and of the direction of the meridional flow. Mixing in the form of velocity pulsations generated by the inductor within the melt would be if interest from the standpoint of affecting the crystallization processes, in particular to intensify the crystallization purification. The authors propose the use of a double magnetohydrodynmic rotator which consists of two rotating magnetic-field inductors, separated in altitude, with separate power supplies. The supply of power to the inductors with various current loads allows the generation of a controllable nonuniformity in field distribution and in the azimuthal velocity through the altitude and thus allows control of both the intensity and configuration of the meridional flows. The dual rotator makes it possible to purposefully control the structure of the meridional flows and the pulsation component of velocity and can be recommended for use in processes of directed crystallization as well as in crystallization purification. 4 refs., 3 figs

  20. The ATP hydrolysis and phosphate release steps control the time course of force development in rabbit skeletal muscle.

    Science.gov (United States)

    Sleep, John; Irving, Malcolm; Burton, Kevin

    2005-03-15

    The time course of isometric force development following photolytic release of ATP in the presence of Ca(2+) was characterized in single skinned fibres from rabbit psoas muscle. Pre-photolysis force was minimized using apyrase to remove contaminating ATP and ADP. After the initial force rise induced by ATP release, a rapid shortening ramp terminated by a step stretch to the original length was imposed, and the time course of the subsequent force redevelopment was again characterized. Force development after ATP release was accurately described by a lag phase followed by one or two exponential components. At 20 degrees C, the lag was 5.6 +/- 0.4 ms (s.e.m., n = 11), and the force rise was well fitted by a single exponential with rate constant 71 +/- 4 s(-1). Force redevelopment after shortening-restretch began from about half the plateau force level, and its single-exponential rate constant was 68 +/- 3 s(-1), very similar to that following ATP release. When fibres were activated by the addition of Ca(2+) in ATP-containing solution, force developed more slowly, and the rate constant for force redevelopment following shortening-restretch reached a maximum value of 38 +/- 4 s(-1) (n = 6) after about 6 s of activation. This lower value may be associated with progressive sarcomere disorder at elevated temperature. Force development following ATP release was much slower at 5 degrees C than at 20 degrees C. The rate constant of a single-exponential fit to the force rise was 4.3 +/- 0.4 s(-1) (n = 22), and this was again similar to that after shortening-restretch in the same activation at this temperature, 3.8 +/- 0.2 s(-1). We conclude that force development after ATP release and shortening-restretch are controlled by the same steps in the actin-myosin ATPase cycle. The present results and much previous work on mechanical-chemical coupling in muscle can be explained by a kinetic scheme in which force is generated by a rapid conformational change bracketed by two

  1. Grip Strength and Its Relationship to Police Recruit Task Performance and Injury Risk: A Retrospective Cohort Study.

    Science.gov (United States)

    Orr, Robin; Pope, Rodney; Stierli, Michael; Hinton, Benjamin

    2017-08-21

    Suitable grip strength is a police occupational requirement. The aim of this study was to investigate the association between grip strength, task performance and injury risk in a police population. Retrospective data of police recruits (n = 169) who had undergone basic recruit training were provided, including handgrip strength results, occupational task performance measures (consisting of police task simulations [SIM], tactical options [TACOPS] and marksmanship assessments) and injury records. Left hand grip strength (41.91 ± 8.29 kg) measures showed a stronger correlation than right hand grip strength (42.15 ± 8.53 kg) with all outcome measures. Recruits whose grip strength scores were lower were significantly more susceptible to failing the TACOPS occupational task assessment than those with greater grip strength scores, with significant ( p ≤ 0.003) weak to moderate, positive correlations found between grip strength and TACOPS performance. A significant ( p performance, with those performing better in marksmanship having higher grip strength. Left hand grip strength was significantly associated with injury risk ( r = -0.181, p = 0.018) but right hand grip strength was not. A positive association exists between handgrip strength and police recruit task performance (notably TACOPS and marksmanship) with recruits who scored poorly on grip strength being at greatest risk of occupational assessment task failure.

  2. An Artificial Neural Network Modeling for Force Control System of a Robotic Pruning Machine

    Directory of Open Access Journals (Sweden)

    Ali Hashemi

    2014-06-01

    Full Text Available Nowadays, there has been an increasing application of pruning robots for planted forests due to the growing concern on the efficiency and safety issues. Power consumption and working time of agricultural machines have become important issues due to the high value of energy in modern world. In this study, different multi-layer back-propagation networks were utilized for mapping the complex and highly interactive of pruning process parameters and to predict power consumption and cutting time of a force control equipped robotic pruning machine by knowing input parameters such as: rotation speed, stalk diameter, and sensitivity coefficient. Results showed significant effects of all input parameters on output parameters except rotational speed on cutting time. Therefore, for reducing the wear of cutting system, a less rotational speed in every sensitivity coefficient should be selected.

  3. Effect of Isometric Hand Grip Exercises on Blood Flow and Placement of IV Catheters for Administration of Chemotherapy.

    Science.gov (United States)

    Ozkaraman, Ayse; Yesilbalkan, Öznur Usta

    2016-04-01

    Complications may occur in the subcutaneous or subdermal tissues during IV administration of chemotherapy related to blood flow and catheter placement. Daily isometric hand grip exercises were evaluated for their effect on blood flow in the vessels of the nondominant arm before placement of IV catheters and the success rate of IV catheter placement on the first attempt. The study focused on patients with non-Hodgkin lymphoma receiving the first and second cycles of chemotherapy. The intervention group performed daily isometric hand grip exercises before chemotherapy with peripheral catheter insertion. The control group performed routine activities only. Blood flow was measured by ultrasound in the brachial artery (BA) and brachial vein (BV) of the nondominant arm before the first (T1) and second (T2) cycles of chemotherapy. Blood flow slightly increased in the intervention group at T2 compared to T1. In the control group, blood flow decreased in the BA and did not change in the BV at T2 compared to T1. The success rate for first-attempt placement of a peripheral IV catheter was the same for the intervention and control groups.

  4. Characterization of the disruption of neural control strategies for dynamic fingertip forces from attractor reconstruction.

    Directory of Open Access Journals (Sweden)

    Lorenzo Peppoloni

    Full Text Available The Strength-Dexterity (SD test measures the ability of the pulps of the thumb and index finger to compress a compliant and slender spring prone to buckling at low forces (<3N. We know that factors such as aging and neurodegenerative conditions bring deteriorating physiological changes (e.g., at the level of motor cortex, cerebellum, and basal ganglia, which lead to an overall loss of dexterous ability. However, little is known about how these changes reflect upon the dynamics of the underlying biological system. The spring-hand system exhibits nonlinear dynamical behavior and here we characterize the dynamical behavior of the phase portraits using attractor reconstruction. Thirty participants performed the SD test: 10 young adults, 10 older adults, and 10 older adults with Parkinson's disease (PD. We used delayed embedding of the applied force to reconstruct its attractor. We characterized the distribution of points of the phase portraits by their density (number of distant points and interquartile range and geometric features (trajectory length and size. We find phase portraits from older adults exhibit more distant points (p = 0.028 than young adults and participants with PD have larger interquartile ranges (p = 0.001, trajectory lengths (p = 0.005, and size (p = 0.003 than their healthy counterparts. The increased size of the phase portraits with healthy aging suggests a change in the dynamical properties of the system, which may represent a weakening of the neural control strategy. In contrast, the distortion of the attractor in PD suggests a fundamental change in the underlying biological system, and disruption of the neural control strategy. This ability to detect differences in the biological mechanisms of dexterity in healthy and pathological aging provides a simple means to assess their disruption in neurodegenerative conditions and justifies further studies to understand the link with the physiological changes.

  5. Fuel assembly gripping device using self-locking mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Lee, G. M.; Choi, S.; Kim, K. S.; Kim, T. W.; Jeong, K. H.; Park, K. B.; Chang, M. H

    1999-07-01

    This report presents an actuating principles and structure for two kind of the fuel assembly gripping devices (Gripper-A, B) developed for SMART. The main components of these grippers are push bundle, rotation bundle, upper guide tube and chuck assembly. The rope attached to winch system on moving cask hangs gripper's push bundle. Due to a down-and-up operation of winch system, the push bundle pushes crown teeth shaped rotation bundle and then it is pushed down and rotated counter clockwise. The push-and-pull sequential operation of push bundle makes the rotation bundle is pushed, rotated and returned, moreover it makes the chuck assembly is expanded or shrunk. The expansion and shrinkage motion of chuck assembly makes the gripper latch and release the fuel assembly. Gripper-A suits for the handling of the fuel assembly with square shaped latching hole. Otherwise Gripper-B suits for a circular shaped latching hole. (author). 5 refs., 20 figs.

  6. An Open Source Low-Cost Wireless Control System for a Forced Circulation Solar Plant.

    Science.gov (United States)

    Salamone, Francesco; Belussi, Lorenzo; Danza, Ludovico; Ghellere, Matteo; Meroni, Italo

    2015-11-05

    The article describes the design phase, development and practical application of a low-cost control system for a forced circulation solar plant in an outdoor test cell located near Milan. Such a system provides for the use of an electric pump for the circulation of heat transfer fluid connecting the solar thermal panel to the storage tank. The running plant temperatures are the fundamental parameter to evaluate the system performance such as proper operation, and the control and management system has to consider these parameters. A solar energy-powered wireless-based smart object was developed, able to monitor the running temperatures of a solar thermal system and aimed at moving beyond standard monitoring approaches to achieve a low-cost and customizable device, even in terms of installation in different environmental conditions. To this end, two types of communications were used: the first is a low-cost communication based on the ZigBee protocol used for control purposes, so that it can be customized according to specific needs, while the second is based on a Bluetooth protocol used for data display.

  7. An Open Source Low-Cost Wireless Control System for a Forced Circulation Solar Plant

    Directory of Open Access Journals (Sweden)

    Francesco Salamone

    2015-11-01

    Full Text Available The article describes the design phase, development and practical application of a low-cost control system for a forced circulation solar plant in an outdoor test cell located near Milan. Such a system provides for the use of an electric pump for the circulation of heat transfer fluid connecting the solar thermal panel to the storage tank. The running plant temperatures are the fundamental parameter to evaluate the system performance such as proper operation, and the control and management system has to consider these parameters. A solar energy-powered wireless-based smart object was developed, able to monitor the running temperatures of a solar thermal system and aimed at moving beyond standard monitoring approaches to achieve a low-cost and customizable device, even in terms of installation in different environmental conditions. To this end, two types of communications were used: the first is a low-cost communication based on the ZigBee protocol used for control purposes, so that it can be customized according to specific needs, while the second is based on a Bluetooth protocol used for data display.

  8. Vitamin D status predicts hand-grip strength in young adult women living in Auckland, New Zealand.

    Science.gov (United States)

    von Hurst, P R; Conlon, C; Foskett, A

    2013-07-01

    The identification of the vitamin D receptor (VDR) in skeletal muscle tissue and research in muscle strength and development in VDR-null mice confirms a role for vitamin D in muscle function. The relationship between muscle strength and vitamin D status has been explored to some degree in older populations with regard to fall prevention, but there has been very little research in younger adults. This cross-sectional study considered the predictors of muscle strength in 137 young women (19-29 years) living in New Zealand. The following measurements were taken in the latter months of winter: plasma 25OHD, dominant (HGD) and non-dominant hand-grip (HGND) strength (hand-grip dynamometer), counter measure jump, and recreational physical activity (RPA) assessed from a recent physical activity questionnaire (RPAQ). Dietary intake was measured with a four-day food diary, and body composition using air displacement plethysmography. This was a relatively inactive group of women; total RPA ranged from 0 to 3.93h per week, mean (SD) 0.86(0.74) h, approximately 50% comprised outdoor activities. Mean 25OHD was 54(28)nmol/l, HGD and HGND were significantly different (t=6.049, pstrength as the dependent variable (Model R(2)=0.11, p=0.001 non-dominant, R(2)=0.13, pstrength and serum 25OHD, and when each were adjusted to remove this association, 25OHD accounted for 4.3% of HGND and 4.5% of HGD. These results suggest that vitamin D status does have a small but significant association with hand-grip strength in this group of young women. Further investigation in this age group with a randomised controlled trial is justified. This article is part of a Special Issue entitled 'Vitamin D Workshop'. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Force-controlled absorption in a fully-nonlinear numerical wave tank

    International Nuclear Information System (INIS)

    Spinneken, Johannes; Christou, Marios; Swan, Chris

    2014-01-01

    An active control methodology for the absorption of water waves in a numerical wave tank is introduced. This methodology is based upon a force-feedback technique which has previously been shown to be very effective in physical wave tanks. Unlike other methods, an a-priori knowledge of the wave conditions in the tank is not required; the absorption controller being designed to automatically respond to a wide range of wave conditions. In comparison to numerical sponge layers, effective wave absorption is achieved on the boundary, thereby minimising the spatial extent of the numerical wave tank. In contrast to the imposition of radiation conditions, the scheme is inherently capable of absorbing irregular waves. Most importantly, simultaneous generation and absorption can be achieved. This is an important advance when considering inclusion of reflective bodies within the numerical wave tank. In designing the absorption controller, an infinite impulse response filter is adopted, thereby eliminating the problem of non-causality in the controller optimisation. Two alternative controllers are considered, both implemented in a fully-nonlinear wave tank based on a multiple-flux boundary element scheme. To simplify the problem under consideration, the present analysis is limited to water waves propagating in a two-dimensional domain. The paper presents an extensive numerical validation which demonstrates the success of the method for a wide range of wave conditions including regular, focused and random waves. The numerical investigation also highlights some of the limitations of the method, particularly in simultaneously generating and absorbing large amplitude or highly-nonlinear waves. The findings of the present numerical study are directly applicable to related fields where optimum absorption is sought; these include physical wavemaking, wave power absorption and a wide range of numerical wave tank schemes

  10. Effect of Putting Grip on Eye and Head Movements During the Golf Putting Stroke

    Directory of Open Access Journals (Sweden)

    George K. Hung

    2003-01-01

    Full Text Available The objective of this article is to determine the effect of three different putting grips (conventional, cross-hand, and one-handed on variations in eye and head movements during the putting stroke. Seven volunteer novice players, ranging in age from 21 to 22 years, participated in the study. During each experimental session, the subject stood on a specially designed platform covered with artificial turf and putted golf balls towards a standard golf hole. The three different types of grips were tested at two distances: 3 and 9 ft. For each condition, 20 putts were attempted. For each putt, data were recorded over a 3-s interval at a sampling rate of 100 Hz. Eye movements were recorded using a helmet-mounted eye movement monitor. Head rotation about an imaginary axis through the top of the head and its center-of-rotation was measured by means of a potentiometer mounted on a fixed frame and coupled to the helmet. Putter-head motion was measured using a linear array of infrared phototransistors embedded in the platform. The standard deviation (STD, relative to the initial level was calculated for eye and head movements over the duration of the putt (i.e., from the beginning of the backstroke, through the forward stroke, to impact. The averaged STD for the attempted putts was calculated for each subject. Then, the averaged STDs and other data for the seven subjects were statistically compared across the three grip conditions. The STD of eye movements were greater (p < 0.1 for conventional than cross-hand (9 ft and one-handed (3 and 9 ft grips. Also, the STD of head movements were greater (p < 0.1; 3 ft for conventional than cross-hand and one-handed grips. Vestibulo-ocular responses associated with head rotations could be observed in many 9 ft and some 3 ft putts. The duration of the putt was significantly longer (p < 0.05; 3 and 9 ft for the one-handed than conventional and cross-hand grips. Finally, performance, or percentage putts made, was

  11. Controller design for automatic micro-assembly systems under the influence of surface forces, hysteresis and quantizer

    NARCIS (Netherlands)

    Ouyang, Ruiyue; Jayawardhana, Bayu

    In this paper, we design nonlinear controllers for micro-magnetic levitation systems. The controller takes into account the influence of the surface forces and hysteresis/quantizer. We show the exponential convergence of the error signal and its time derivative to a compact set, which is determined

  12. Improvement of handle grip using reverse engineering, CAE and Rapid Prototyping

    Directory of Open Access Journals (Sweden)

    Stoklasek Pavel

    2016-01-01

    Full Text Available The overwhelming majority of manual operations is even nowadays performed by using manual hand tools. These tools can be divided into 2 groups – hand tools designed for general use or a single-purpose hand tools for special operations. Tool described in this paper is used in assembling operation in the completion of electric motor. During the design of the existing tools the requirements for a functional part of the tool (lifespan, inability to damage the engine installation were fully considered, demands for ergonomic grip area, however, were not taken into account. Long-term use of incorrectly designed tool causes carpal tunnel syndrome, hand-arm vibration syndrome, diminished sensitivity or tingling in the fingers of workers. These difficulties can be reduced or entirely eliminated due to proper design of the grip of hand tool. Most authors focus on adjusting the grip for optimum ergonomics at individual types of grips (cylindrical, palmar, lateral, etc.. However, as already mentioned, there are tools for specific operations when the working area is limited by space or a specific type of load on the grip is needed. In some cases, it is often necessary to change the type of grip or combine different types of grips. This paper describes the design of an optimal grip of hand tool used for specific operation when assembling motors. Design of prototype mold and production of functional prototypes for ergonomics assessment directly in the workplace were realized. New design of handle should reduce the risk primarily of developing carpal tunnel in long-term use.

  13. Grip strength in mice with joint inflammation: A rheumatology function test sensitive to pain and analgesia.

    Science.gov (United States)

    Montilla-García, Ángeles; Tejada, Miguel Á; Perazzoli, Gloria; Entrena, José M; Portillo-Salido, Enrique; Fernández-Segura, Eduardo; Cañizares, Francisco J; Cobos, Enrique J

    2017-10-01

    Grip strength deficit is a measure of pain-induced functional disability in rheumatic disease. We tested whether this parameter and tactile allodynia, the standard pain measure in preclinical studies, show parallels in their response to analgesics and basic mechanisms. Mice with periarticular injections of complete Freund's adjuvant (CFA) in the ankles showed periarticular immune infiltration and synovial membrane alterations, together with pronounced grip strength deficits and tactile allodynia measured with von Frey hairs. However, inflammation-induced tactile allodynia lasted longer than grip strength alterations, and therefore did not drive the functional deficits. Oral administration of the opioid drugs oxycodone (1-8 mg/kg) and tramadol (10-80 mg/kg) induced a better recovery of grip strength than acetaminophen (40-320 mg/kg) or the nonsteroidal antiinflammatory drugs ibuprofen (10-80 mg/kg) or celecoxib (40-160 mg/kg); these results are consistent with their analgesic efficacy in humans. Functional impairment was generally a more sensitive indicator of drug-induced analgesia than tactile allodynia, as drug doses that attenuated grip strength deficits showed little or no effect on von Frey thresholds. Finally, ruthenium red (a nonselective TRP antagonist) or the in vivo ablation of TRPV1-expressing neurons with resiniferatoxin abolished tactile allodynia without altering grip strength deficits, indicating that the neurobiology of tactile allodynia and grip strength deficits differ. In conclusion, grip strength deficits are due to a distinct type of pain that reflects an important aspect of the human pain experience, and therefore merits further exploration in preclinical studies to improve the translation of new analgesics from bench to bedside. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Getting a Grip on the Handgrip Task: Handgrip Duration Correlates with Neuroticism But Not Conscientiousness

    Directory of Open Access Journals (Sweden)

    Simon B. Goldberg

    2017-08-01

    Full Text Available Questions regarding the replicability of key findings in the self-regulation literature (e.g., ego-depletion effect have led some to call for a more thorough evaluation of commonly used measures of self-control. The isometric handgrip task is one such measure. The current study examined correlates of handgrip persistence using data drawn from a larger randomized controlled trial. Handgrip persistence was measured both at baseline and following a physical stressor (cold pressor test. Correlations were examined between handgrip performance and personality traits theoretically closely linked with self-regulation: conscientiousness and neuroticism. Baseline handgrip performance was correlated with several measures drawn from the nomological network of self-regulation including measures of trait neuroticism, mindfulness, anxiety sensitivity, perceived stress, and positive affect, although not with trait conscientiousness. Baseline handgrip predicted aversiveness experienced during the physical stressor, while changes in handgrip performance tracked changes in implicit and explicit negative affect (i.e., affective reactivity. These associations were largely maintained when controlling for variables highly correlated with overall grip strength (i.e., gender, height, and weight, although correlations separated by gender suggest associations were primarily driven by female participants. Results support future research using the handgrip task.

  15. Predicting hand function in older adults: evaluations of grip strength, arm curl strength, and manual dexterity.

    Science.gov (United States)

    Liu, Chiung-Ju; Marie, Deana; Fredrick, Aaron; Bertram, Jessica; Utley, Kristen; Fess, Elaine Ewing

    2017-08-01

    Hand function is critical for independence in activities of daily living for older adults. The purpose of this study was to examine how grip strength, arm curl strength, and manual dexterous coordination contributed to time-based versus self-report assessment of hand function in community-dwelling older adults. Adults aged ≥60 years without low vision or neurological disorders were recruited. Purdue Pegboard Test, Jamar hand dynamometer, 30-second arm curl test, Jebsen-Taylor Hand Function Test, and the Late-Life Function and Disability Instrument were administered to assess manual dexterous coordination, grip strength, arm curl strength, time-based hand function, and self-report of hand function, respectively. Eighty-four adults (mean age = 72 years) completed the study. Hierarchical multiple regressions show that older adults with better arm curl strength (β = -.25, p function test. In comparison, older adults with better grip strength (β = .40, p function. The relationship between grip strength and hand function may be test-specific. Grip strength becomes a significant factor when the test requires grip strength to successfully complete the test tasks. Arm curl strength independently contributed to hand function in both time-based and self-report assessments, indicating that strength of extrinsic muscles of the hand are essential for hand function.

  16. Hold, grasp, clutch or grab: consumer grip choices during food container opening.

    Science.gov (United States)

    Rowson, J; Yoxall, A

    2011-07-01

    Society is ageing and sadly that ageing leads to a host of issues, not least a society in which the majority are likely to have some loss of strength and dexterity. This can lead to complications in undertaking everyday tasks such as using transport, bathing or even handling and opening food. Packaging has to provide a multitude of services; to protect and preserve the product, to provide information to the consumer and not least to allow access to the contents. This access to packaging--or 'openability'--has become a significant issue for designers and manufacturers with the change in demographics as described above. Understanding the choices consumers make in how they manipulate packaging can help designers produce packaging that is more able to meet the requirements of modern society. Studies previously undertaken by the authors showed that consumers did use different grips when opening packaging and that certain grips were theoretically more comfortable and stronger than others. This paper outlines a further study whereby consumers were asked to apply the most common grips to a specially designed torque measuring device. Details were taken about the consumers: age, gender, occupation, hand size, plus their preferred grip choice for packaging of this type. The study showed that typically women chose a grip that maximised their opportunity of opening the closure and that this grip choice was more limited than that available for men. This has implications for inclusive design of many everyday products. Copyright © 2010 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  17. Capabilities and Limitations of Tissue Size Control through Passive Mechanical Forces.

    Directory of Open Access Journals (Sweden)

    Jochen Kursawe

    2015-12-01

    Full Text Available Embryogenesis is an extraordinarily robust process, exhibiting the ability to control tissue size and repair patterning defects in the face of environmental and genetic perturbations. The size and shape of a developing tissue is a function of the number and size of its constituent cells as well as their geometric packing. How these cellular properties are coordinated at the tissue level to ensure developmental robustness remains a mystery; understanding this process requires studying multiple concurrent processes that make up morphogenesis, including the spatial patterning of cell fates and apoptosis, as well as cell intercalations. In this work, we develop a computational model that aims to understand aspects of the robust pattern repair mechanisms of the Drosophila embryonic epidermal tissues. Size control in this system has previously been shown to rely on the regulation of apoptosis rather than proliferation; however, to date little work has been done to understand the role of cellular mechanics in this process. We employ a vertex model of an embryonic segment to test hypotheses about the emergence of this size control. Comparing the model to previously published data across wild type and genetic perturbations, we show that passive mechanical forces suffice to explain the observed size control in the posterior (P compartment of a segment. However, observed asymmetries in cell death frequencies across the segment are demonstrated to require patterning of cellular properties in the model. Finally, we show that distinct forms of mechanical regulation in the model may be distinguished by differences in cell shapes in the P compartment, as quantified through experimentally accessible summary statistics, as well as by the tissue recoil after laser ablation experiments.

  18. A novel vehicle dynamics stability control algorithm based on the hierarchical strategy with constrain of nonlinear tyre forces

    Science.gov (United States)

    Li, Liang; Jia, Gang; Chen, Jie; Zhu, Hongjun; Cao, Dongpu; Song, Jian

    2015-08-01

    Direct yaw moment control (DYC), which differentially brakes the wheels to produce a yaw moment for the vehicle stability in a steering process, is an important part of electric stability control system. In this field, most control methods utilise the active brake pressure with a feedback controller to adjust the braked wheel. However, the method might lead to a control delay or overshoot because of the lack of a quantitative project relationship between target values from the upper stability controller to the lower pressure controller. Meanwhile, the stability controller usually ignores the implementing ability of the tyre forces, which might be restrained by the combined-slip dynamics of the tyre. Therefore, a novel control algorithm of DYC based on the hierarchical control strategy is brought forward in this paper. As for the upper controller, a correctional linear quadratic regulator, which not only contains feedback control but also contains feed forward control, is introduced to deduce the object of the stability yaw moment in order to guarantee the yaw rate and side-slip angle stability. As for the medium and lower controller, the quantitative relationship between the vehicle stability object and the target tyre forces of controlled wheels is proposed to achieve smooth control performance based on a combined-slip tyre model. The simulations with the hardware-in-the-loop platform validate that the proposed algorithm can improve the stability of the vehicle effectively.

  19. Intelligent tuning method of PID parameters based on iterative learning control for atomic force microscopy.

    Science.gov (United States)

    Liu, Hui; Li, Yingzi; Zhang, Yingxu; Chen, Yifu; Song, Zihang; Wang, Zhenyu; Zhang, Suoxin; Qian, Jianqiang

    2018-01-01

    Proportional-integral-derivative (PID) parameters play a vital role in the imaging process of an atomic force microscope (AFM). Traditional parameter tuning methods require a lot of manpower and it is difficult to set PID parameters in unattended working environments. In this manuscript, an intelligent tuning method of PID parameters based on iterative learning control is proposed to self-adjust PID parameters of the AFM according to the sample topography. This method gets enough information about the output signals of PID controller and tracking error, which will be used to calculate the proper PID parameters, by repeated line scanning until convergence before normal scanning to learn the topography. Subsequently, the appropriate PID parameters are obtained by fitting method and then applied to the normal scanning process. The feasibility of the method is demonstrated by the convergence analysis. Simulations and experimental results indicate that the proposed method can intelligently tune PID parameters of the AFM for imaging different topographies and thus achieve good tracking performance. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Modeling and analysis of a robust thermal control system based on forced convection thermal switches

    Science.gov (United States)

    Williams, Andrew D.; Palo, Scott E.

    2006-05-01

    There is a critical need, not just in the Department of Defense (DOD) but the entire space industry, to reduce the development time and overall cost of satellite missions. To that end, the DOD is actively pursuing the capability to reduce the deployment time of a new system from years to weeks or even days. The goal is to provide the advantages space affords not just to the strategic planner but also to the battlefield commanders. One of the most challenging aspects of this problem is the satellite's thermal control system (TCS). Traditionally the TCS must be vigorously designed, analyzed, tested, and optimized from the ground up for every satellite mission. This "reinvention of the wheel" is costly and time intensive. The next generation satellite TCS must be modular and scalable in order to cover a wide range of applications, orbits, and mission requirements. To meet these requirements a robust thermal control system utilizing forced convection thermal switches was investigated. The problem was investigated in two separate stages. The first focused on the overall design of the bus. The second stage focused on the overarching bus architecture and the design impacts of employing a thermal switch based TCS design. For the hot case, the fan provided additional cooling to increase the heat transfer rate of the subsystem. During the cold case, the result was a significant reduction in survival heater power.

  1. STRUCTURE CONTROL FOR DIFFERENT TYPES OF PAPER BY ATOMIC FORCE MICROSCOPY

    Directory of Open Access Journals (Sweden)

    M. V. Zhukov

    2014-01-01

    Full Text Available The paper deals with the precision control for the parameters of manufactured paper production, such as various kinds of paper and photo paper for printing. Research of untreated, matte, glossy and laminated paper is conducted by atomic force microscopy by means of educational and scientific scanning probe microscope NanoEducator LE in the framework of this paper. Visualization of characteristic structure for each type of studied paper was conducted, histogram of roughness was obtained, and average roughness of height differences was defined. A laminated paper has got the lowest roughness (Ra of about 70 nm and glossy paper has got Ra of about 170 nm; roughness of untreated paper with cellulose fibers is about 530- 540 nm, and matte paper has got the highest roughness parameters (Ra about 670-680 nm. Scanning probe microscopy application for parameters monitoring of cellulosic paper production is shown to give the possibility of such microscopy type application in the production of paper products and high-precision control of its parameters.

  2. Controlled manipulation of flexible carbon nanotubes through shape-dependent pushing by atomic force microscopy.

    Science.gov (United States)

    Yang, Seung-Cheol; Qian, Xiaoping

    2013-09-17

    A systematic approach to manipulating flexible carbon nanotubes (CNTs) has been developed on the basis of atomic force microscope (AFM) based pushing. Pushing CNTs enables efficient transport and precise location of individual CNTs. A key issue for pushing CNTs is preventing defective distortion in repetitive bending and unbending deformation. The approach presented here controls lateral movement of an AFM tip to bend CNTs without permanent distortion. The approach investigates possible defects caused by tensile strain of the outer tube under uniform bending and radial distortion by kinking. Using the continuum beam model and experimental bending tests, dependency of maximum bending strain on the length of bent CNTs and radial distortion on bending angles at a bent point have been demonstrated. Individual CNTs are manipulated by limiting the length of bent CNTs and the bending angle. In our approach, multiwalled CNTs with 5-15 nm diameter subjected to bending deformation produce no outer tube breakage under uniform bending and reversible radial deformation with bending angles less than 110°. The lateral tip movement is determined by a simple geometric model that relies on the shape of multiwalled CNTs. The model effectively controls deforming CNT length and bending angle for given CNT shape. Experimental results demonstrate successful manipulation of randomly dispersed CNTs without visual defects. This approach to pushing can be extended to develop a wide range of CNT based nanodevice applications.

  3. Reynolds stress analysis of EMHD-controlled wall turbulence. Part I. Streamwise forcing

    International Nuclear Information System (INIS)

    Crawford, C.H.; Karniadakis, G.E.

    1997-01-01

    In this work we investigate numerically turbulent flow of low electrical conductivity fluid subject to electro-magnetic (EMHD) forcing. The configuration is similar to the one considered in the experimental work of Henoch and Stace [Phys. Fluids 7, 1371 (1995)] but in a channel geometry. The lower wall of the channel is covered with alternating streamwise electrodes and magnets to create a Lorentz force in the positive streamwise direction. Two cases are considered in detail corresponding to interaction parameter values of 0.4 (case 1) and 0.1 (case 2). The effect of switching off and on the electrodes is also studied for the two cases. At the Reynolds number considered (Re τ ∼200), a drag increase was obtained for all cases, in agreement with the experiments of Henoch and Stace. A Reynolds stress analysis was performed based on a new decomposition of the gradients normal to the wall of the Reynolds stress -u'v'. It was found that the vortex stretching term w'w 2 ' and the spanwise variation of the stress component u'w' are responsible for the drag increase. More specifically, the term ∂(u'w')/∂x 3 is associated with secondary vortical motions in the near-wall and becomes large and positive for large shear stress in regions where fluid is moving toward the wall. In contrast, negative values are associated with regions of lower shear where fluid is being lifted away from the wall. Unlike the unperturbed flow, in the controlled flow high speed near-wall streamwise jets are present (case 1) even in the time-averaged fields. Other changes in turbulence structure are quantified using streak spacing, vortex lines, vorticity quadrant analysis, and plots of the rms value of the vorticity angle. copyright 1997 American Institute of Physics

  4. Conceptual Design Study on Electromagnets of Control Rod Drive Mechanism of a SFR

    International Nuclear Information System (INIS)

    Lee, Jaehan; Koo, Gyeonghoi

    2013-01-01

    The prototype SFR has six primary control rod assemblies(CRAs) and three secondary shutdown assemblies. The primary control system is used for power control, burnup compensation and reactor shutdown in response to demands from the plant control or protection systems. This paper describes the design concept of primary control rod drive mechanism shortly, and performs the parametric design studies for the electromagnet device of the drive mechanism to maximize CRA gripping force. The electromagnetic core usually confines and guides the magnetic field. The major parameters influenced on the electromagnetic force are the geometry and arrangement of the electromagnet and armature for a given coil specification. A typical equation calculating the electromagnetic force for a solenoid type is represented in equation. The first one is the increasing of the flux cross section area (Α c , Α g ) in magnetic field connecting of air gap, armature and electromagnets. Secondly, the reducing of the path lengths (l c , l g ) of the armature and electromagnet makes the magnetic flux (Β) resistance to be low. An electromagnet field analyses are performed for the initial design values of the electromagnet device. The gripping force is about 3 times of CRA weight when one coil is power on. The parametric studies on air gap, core sizes configuring of the electromagnet cores are performed to maximize the electromagnetic force

  5. Pneumatic Artificial Muscles Force Modelling and the Position and Stiffness Control on the Knee Joint of the Musculoskeletal Leg

    Directory of Open Access Journals (Sweden)

    Jingtao Lei

    2017-03-01

    Full Text Available Pneumatic artificial muscles (PAMs have properties similar to biological muscle and are widely used in robotics as actuators. A musculoskeletal leg mechanism driven by PAMs is presented in this paper. The joint stiffness of the musculoskeletal bionic leg for jumping movement needs to be analysed. The synchronous control on the position and stiffness of the joint is important to improve the flexibility of leg. The accurate force model of PAM is the foundation to achieving better control and dynamic jumping performance. The experimental platform of PAM is conducted, and the static equal pressure experiments are performed to obtain the PAM force model. According to the testing data, parameter identification method is adopted to determine the force model of PAM. A simulation on the position and stiffness control of the knee joint is performed, and the simulation results show the effectiveness of the presented method.

  6. Flight mechanics and control of escape manoeuvres in hummingbirds. II. Aerodynamic force production, flight control and performance limitations.

    Science.gov (United States)

    Cheng, Bo; Tobalske, Bret W; Powers, Donald R; Hedrick, Tyson L; Wang, Yi; Wethington, Susan M; Chiu, George T-C; Deng, Xinyan

    2016-11-15

    The superior manoeuvrability of hummingbirds emerges from complex interactions of specialized neural and physiological processes with the unique flight dynamics of flapping wings. Escape manoeuvring is an ecologically relevant, natural behaviour of hummingbirds, from which we can gain understanding into the functional limits of vertebrate locomotor capacity. Here, we extend our kinematic analysis of escape manoeuvres from a companion paper to assess two potential limiting factors of the manoeuvring performance of hummingbirds: (1) muscle mechanical power output and (2) delays in the neural sensing and control system. We focused on the magnificent hummingbird (Eugenes fulgens, 7.8 g) and the black-chinned hummingbird (Archilochus alexandri, 3.1 g), which represent large and small species, respectively. We first estimated the aerodynamic forces, moments and the mechanical power of escape manoeuvres using measured wing kinematics. Comparing active-manoeuvring and passive-damping aerodynamic moments, we found that pitch dynamics were lightly damped and dominated by the effect of inertia, while roll dynamics were highly damped. To achieve observed closed-loop performance, pitch manoeuvres required faster sensorimotor transduction, as hummingbirds can only tolerate half the delay allowed in roll manoeuvres. Accordingly, our results suggested that pitch control may require a more sophisticated control strategy, such as those based on prediction. For the magnificent hummingbird, we estimated that escape manoeuvres required muscle mass-specific power 4.5 times that during hovering. Therefore, in addition to the limitation imposed by sensorimotor delays, muscle power could also limit the performance of escape manoeuvres. © 2016. Published by The Company of Biologists Ltd.

  7. Analysis and control of the compaction force in the composite prepreg tape winding process for rocket motor nozzles

    Directory of Open Access Journals (Sweden)

    Xiaodong He

    2017-04-01

    Full Text Available In the process of composite prepreg tape winding, the compaction force could influence the quality of winding products. According to the analysis and experiments, during the winding process of a rocket motor nozzle aft exit cone with a winding angle, there would be an error between the deposition speed of tape layers and the feeding speed of the compaction roller, which could influence the compaction force. Both a lack of compaction and overcompaction related to the feeding of the compaction roller could result in defects of winding nozzles. Thus, a flexible winding system has been developed for rocket motor nozzle winding. In the system, feeding of the compaction roller could be adjusted in real time to achieve an invariable compaction force. According to experiments, the force deformation model of the winding tape is a time-varying system. Thus, a forgetting factor recursive least square based parameter estimation proportional-integral-differential (PID controller has been developed, which could estimate the time-varying parameter and control the compaction force by adjusting the feeding of the compaction roller during the winding process. According to the experimental results, a winding nozzle with fewer voids and a smooth surface could be wounded by the invariable compaction force in the flexible winding system.

  8. Nursing Education in High Blood Pressure Control. Report of the Task Force on the Role of Nursing in High Blood Pressure Control.

    Science.gov (United States)

    National Institutes of Health (DHEW), Bethesda, MD. High Blood Pressure Information Center.

    This curriculum guide on high blood pressure (hypertension) for nursing educators has five sections: (1) Introduction and Objectives provides information regarding the establishment and objectives of the National Task Force on the Role of Nursing in High Blood Pressure Control and briefly discusses nursing's role in hypertension control; (2) Goals…

  9. Design and implementation of a novel modal space active force control concept for spatial multi-DOF parallel robotic manipulators actuated by electrical actuators.

    Science.gov (United States)

    Yang, Chifu; Zhao, Jinsong; Li, Liyi; Agrawal, Sunil K

    2018-01-01

    Robotic spine brace based on parallel-actuated robotic system is a new device for treatment and sensing of scoliosis, however, the strong dynamic coupling and anisotropy problem of parallel manipulators result in accuracy loss of rehabilitation force control, including big error in direction and value of force. A novel active force control strategy named modal space force control is proposed to solve these problems. Considering the electrical driven system and contact environment, the mathematical model of spatial parallel manipulator is built. The strong dynamic coupling problem in force field is described via experiments as well as the anisotropy problem of work space of parallel manipulators. The effects of dynamic coupling on control design and performances are discussed, and the influences of anisotropy on accuracy are also addressed. With mass/inertia matrix and stiffness matrix of parallel manipulators, a modal matrix can be calculated by using eigenvalue decomposition. Making use of the orthogonality of modal matrix with mass matrix of parallel manipulators, the strong coupled dynamic equations expressed in work space or joint space of parallel manipulator may be transformed into decoupled equations formulated in modal space. According to this property, each force control channel is independent of others in the modal space, thus we proposed modal space force control concept which means the force controller is designed in modal space. A modal space active force control is designed and implemented with only a simple PID controller employed as exampled control method to show the differences, uniqueness, and benefits of modal space force control. Simulation and experimental results show that the proposed modal space force control concept can effectively overcome the effects of the strong dynamic coupling and anisotropy problem in the physical space, and modal space force control is thus a very useful control framework, which is better than the current joint

  10. Analysis and optimization of kinematic pair force in control rod drive mechanism

    International Nuclear Information System (INIS)

    Sun Zhenguo; Liu Sen; Ran Xiaobing; Dai Changnian; Li Yuezhong

    2015-01-01

    Function expressions of kinematic pair force with latch dimensions, friction coefficient, link angle and external load was obtained by theoretical analysis, and the expression was verified by the motion analysis software. Key parameters of kinematic pair were confirmed, and their effect trends with force of parts were obtained. They show that the available method of kinematic pair optimization is increasing the space of latch holes. Using the motion analysis software, the forces of parts before and after optimization was compared. The result shows that the forces of parts were improved after the optimization. (authors)

  11. Grounding by Attention Simulation in Peripersonal Space: Pupils Dilate to Pinch Grip But Not Big Size Nominal Classifier.

    Science.gov (United States)

    Lobben, Marit; Bochynska, Agata

    2018-03-01

    Grammatical categories represent implicit knowledge, and it is not known if such abstract linguistic knowledge can be continuously grounded in real-life experiences, nor is it known what types of mental states can be simulated. A former study showed that attention bias in peripersonal space (PPS) affects reaction times in grammatical congruency judgments of nominal classifiers, suggesting that simulated semantics may include reenactment of attention. In this study, we contrasted a Chinese nominal classifier used with nouns denoting pinch grip objects with a classifier for nouns with big object referents in a pupil dilation experiment. Twenty Chinese native speakers read grammatical and ungrammatical classifier-noun combinations and made grammaticality judgment while their pupillary responses were measured. It was found that their pupils dilated significantly more to the pinch grip classifier than to the big object classifier, indicating attention simulation in PPS. Pupil dilations were also significantly larger with congruent trials on the whole than in incongruent trials, but crucially, congruency and classifier semantics were independent of each other. No such effects were found in controls. Copyright © 2017 Cognitive Science Society, Inc.

  12. Analysis of the effects of hospitalization on fine hand functions compared to gross grip in patients with rheumatoid arthritis

    Directory of Open Access Journals (Sweden)

    Zeynep Tuna

    2015-09-01

    Full Text Available Objective: Hospitalization process causes a variety of physical problems. The decrease of hand use in daily life during hospitalization brings hand dysfunction to mind in inpatients. The aim of this study is to compare the hand functions of hospitalized patients with Rheumatoid Arthritis (RA to outpatients in detail. Methods: Grip and pinch strengths of both hospitalized patients in rheumatology service and outpatients on the routine control day were measured. In addition, 9-Hole Peg Test was performed and the disability level was determined by the Turkish version of Michigan Hand Outcomes Questionnaire (MHOQ. Results: While grip strength and MHOQ scores were similar (p>0.05 in both groups, all three pinch strengths (lateral, bipod, tripod and 9HPT scores were lower (p<0.05 in hospitalized patients. Conclusion: Consequently, besides disease activity, hospitalization process also impairs fine hand functions in rheumatological patients. Evaluation of fine hand functions and appropriate rehabilitative interventions may prevent further disability in hospitalized patients. J Clin Exp Invest 2015; 6 (3: 228-232

  13. ANALYSIS of Control Force Grasping for a Multifunctional Five Fingered Robot to Pick-up Various of Components

    Directory of Open Access Journals (Sweden)

    Widhiada W.

    2016-01-01

    Full Text Available Multi-fingered robot gripper has become popular in the major research topics as grasping an object in robotic systems. The author considers a matter of style-based control model for a multi-fingered robot hand grasping an object with a known geometric characteristics. This paper introduces design process and analysis of contact force the five fingered gripper suitable to handle several of objects. The author applied Simulink/SimMechanics, Support package Arduino and Inventor software packages to facilatate and integrated the design of contact force gripper systems. The advance of PID control is used to control dynamics motions of the five fingered gripper systems. The multifunction finger’s gripper is developed to handle the various components. Contact force between fingertips and object surface is computed using the Hooke law concept. The analysis of experiment result shows the optimum of contact forces are achieved to hold the object. The spring and damper algorithm is used to compute the interaction of force between fingertips and object surface.

  14. Following the surface response of caffeine cocrystals to controlled humidity storage by atomic force microscopy.

    Science.gov (United States)

    Cassidy, A M C; Gardner, C E; Jones, W

    2009-09-08

    Active pharmaceutical ingredient (API) stability in solid state tablet formulation is frequently a function of the relative humidity (RH) environment in which the drug is stored. Caffeine is one such problematic API. Previously reported caffeine cocrystals, however, were found to offer increased resistance to caffeine hydrate formation. Here we report on the use of atomic force microscopy (AFM) to image the surface of two caffeine cocrystal systems to look for differences between the surface and bulk response of the cocrystal to storage in controlled humidity environments. Bulk responses have previously been assessed by powder X-ray diffraction. With AFM, pinning sites were identified at step edges on caffeine/oxalic acid, with these sites leading to non-uniform step movement on going from ambient to 0% RH. At RH >75%, areas of fresh crystal growth were seen on the cocrystal surface. In the case of caffeine/malonic acid the cocrystals were observed to absorb water anisotropically after storage at 75% RH for 2 days, affecting the surface topography of the cocrystal. These results show that AFM expands on the data gathered by bulk analytical techniques, such as powder X-ray diffraction, by providing localised surface information. This surface information may be important for better predicting API stability in isolation and at a solid state API-excipient interface.

  15. Traction control of an electric vehicle based on nonlinear observers

    Directory of Open Access Journals (Sweden)

    Diego A. Aligia

    2017-12-01

    Full Text Available A traction control strategy for a four-wheel electric vehicle is proposed in this paper. The strategy is based on nonlinear observers which allows estimating the maximum force that can be transmitted to the road. Knowledge of the maximum force allows controlling the slip of the driving wheels, preventing the wheel’s slippage in low-grip surfaces. The proposed strategy also allows to avoid the undesired yaw moment in the vehicle which occurs when road conditions on either side of it are dierent. This improves the eciency and the control of the vehicle, avoiding possible losses of stability that can result in risks for its occupants. Both the proposed observer and the control strategy are designed based on a dynamic rotational model of the wheel and a brush force model. Simulation results are obtained based on a complete vehicle model on the Simulink/CarSim platform.

  16. The Future Nuclear Arms Control Agenda and Its Potential Implications for the Air Force

    Science.gov (United States)

    2015-08-01

    US AIR FORCE INSTITUTE FOR NATIONAL SECURITY STUDIES USAF ACADEMY, COLORADO INSS OCCASIONAL PAPER AUGUST 2015 70 Dr. Lewis A. Dunn The Future...Implications for the Air Force Dr. Lewis A. Dunn INSS Occasional Paper 70 August 2015 USAF Institute for National Security Studies USAF

  17. 3D printed flexible capacitive force sensor with a simple micro-controller based readout

    NARCIS (Netherlands)

    Schouten, Martijn G.; Sanders, Remco; Krijnen, Gijs

    2017-01-01

    This paper describes the development of a proof of principle of a flexible force sensor and the corresponding readout circuit. The flexible force sensor consists of a parallel plate capacitor that is 3D printed using regular and conductive thermoplastic poly-urethane (TPU). The capacitance change

  18. Imaging contrast and tip-sample interaction of non-contact amplitude modulation atomic force microscopy with Q -control

    International Nuclear Information System (INIS)

    Shi, Shuai; Guo, Dan; Luo, Jianbin

    2017-01-01

    Active quality factor ( Q ) exhibits many promising properties in dynamic atomic force microscopy. Energy dissipation and image contrasts are investigated in the non-contact amplitude modulation atomic force microscopy (AM-AFM) with an active Q -control circuit in the ambient air environment. Dissipated power and virial were calculated to compare the highly nonlinear interaction of tip-sample and image contrasts with different Q gain values. Greater free amplitudes and lower effective Q values show better contrasts for the same setpoint ratio. Active quality factor also can be employed to change tip-sample interaction force in non-contact regime. It is meaningful that non-destructive and better contrast images can be realized in non-contact AM-AFM by applying an active Q -control to the dynamic system. (paper)