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Sample records for rolling friction robot

  1. Origins of Rolling Friction

    Science.gov (United States)

    Cross, Rod

    2017-01-01

    When a hard object rolls on a soft surface, or vice versa, rolling friction arises from deformation of the soft object or the soft surface. The friction force can be described in terms of an offset in the normal reaction force or in terms of energy loss arising from the deformation. The origin of the friction force itself is not entirely clear. It…

  2. Rolling Friction on a Wheeled Laboratory Cart

    Science.gov (United States)

    Mungan, Carl E.

    2012-01-01

    A simple model is developed that predicts the coefficient of rolling friction for an undriven laboratory cart on a track that is approximately independent of the mass loaded onto the cart and of the angle of inclination of the track. The model includes both deformation of the wheels/track and frictional torque at the axles/bearings. The concept of…

  3. Measurement of Normal and Friction Forces in a Rolling Process

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Wanheim, Tarras

    2004-01-01

    by the fric-tion conditions. To achieve this important informa-tion, measurements of the normal pressure and friction stresses in the deformation zone are re-quested. The direction of the friction stresses is changing during the rolling gap. At the entrance of the de-formation zone, the peripherical velocity...... of the roll is higher than for the incoming material, which causes frictional stresses at the material acting in the rolling direction. At the outlet of the rolling gap, the velocity of the deformed material exceeds the velocity of the roll, generating frictional stresses contrary to the direction of rolling....... In a narrow area in the deformation zone, the velocity of the de-formed material is equal to the velocity of the rolls. This area or line is named “neutral line”. The posi-tion of the neutral line depends on friction, reduc-tion ratio, diameter of the rolls, and width of the sheet....

  4. Assessment of friction between a rolling cylindrical element and a ...

    African Journals Online (AJOL)

    A cost-effective friction coefficient measuring technique was developed and tested. The technique involved the mounting of two sensing elements on the surface of rolls, in a manner that sought to measure simultaneously the normal and the tangential stresses during rolling. The instrumented roll termed “SGRoll” was ...

  5. Using Plasticine (TM) to Measure the Rolling Friction Coefficient.

    Science.gov (United States)

    Castellvi, Francesc; And Others

    1995-01-01

    Presents an experiment that makes manifest the energy lost to friction of an iron ball moving along an inclined iron rail, which allows students to compute the rolling friction coefficient. Uses a method based on measurement of deformation produced in a piece of Plasticine by an inelastic collision with the ball and combines mechanical concepts…

  6. Isotropic compression of cohesive-frictional particles with rolling resistance

    NARCIS (Netherlands)

    Luding, Stefan; Benz, Thomas; Nordal, Steinar

    2010-01-01

    Cohesive-frictional and rough powders are the subject of this study. The behavior under isotropic compression is examined for different material properties involving Coulomb friction, rolling-resistance and contact-adhesion. Under isotropic compression, the density continuously increases according

  7. Methods and devices used to measure friction in rolling

    DEFF Research Database (Denmark)

    Jeswiet, J.; Arentoft, Mogens; Henningsen, Poul

    2006-01-01

    Friction at the workpiece-die boundary, in both bulk forming and sheet forming is, arguably, the single most important physical parameter influencing the processing of metals; yet it remains the least understood. Hence there is a need for basic research into metal-die interface mechanisms. To gain...... a good understanding of the mechanisms at the interface and to be able to verify the friction and tribology models that exist, friction sensors are needed. Designing sensors to measure frictional stress in metal working has been pursued by many researchers. This paper surveys methods that have been used...... to measure friction in rolling in the past and discusses some of the recent sensor designs that can now be used to measure friction both in production situations and for research purposes....

  8. THE THEORETICAL FOUNDATIONS OF VIBRATION DAMPERS BY ROLLING FRICTION

    Directory of Open Access Journals (Sweden)

    L. M. Bondarenko

    2015-06-01

    Full Text Available Purpose. There are some unresolved issues in vibration damping – the lack of engineering calculations for the vibration dampers by rolling friction; the absence of evidence of their application appropriateness. Considering this fact, the authors suggest to prove that the dampers based on rolling friction, are similar in rate of oscillation damping by hydraulic shock absorbers. At the same time, they are easier for the hydraulic design, and easily amenable to manual adjustment, both in automatic and manual mode. Methodology. Fixed techniques of practice in order to determine amplitudes of the oscillations of a shock absorber led to a predetermined result and will apply this theory in the calculation of other vibration dampers. Findings. Analysis of the formulas and graphs leads to the following conclusions and recommendations: 1 the nature of the oscillation damping at vibration dampers by rolling friction is close to their decay in the viscous resistance; 2 when conducting the necessary experiments the shock absorber rolling can be recommended as alternatives to hydraulic ones. The research results of this task will help implement the new trend in reduction of dynamic loads in vehicles. Originality. With the help of theoretical curves to determine the coefficients of rolling friction the dependences for determining the amplitudes of the oscillations in the vertical movement of cargo were obtained. At the same time, the previously proposed analytical dependence for determining the coefficient of rolling friction contains only conventional mechanical constants of the contacting bodies and there geometrical dimensions. Practical value. Due to the existing well-known disadvantages of hydraulic shock absorbers it would be logical to apply shock absorbers that are technologically convenient in manufacturing and easy to adjust the damping rate. The proposed theory can be used in the design of shock absorbers rolling as an alternative to the hydraulic

  9. A new transducer for local load measurements of friction and roll pressure in cold flat rolling

    DEFF Research Database (Denmark)

    Lagergren, J.; Wanheim, Tarras; Precz, W.

    2006-01-01

    The only way to establish the true rolling pressure and the true friction condition in cold rolling is to conduct measurements in the roll bite. A new transducer design is therefore proposed, in order to overcome problems in previous measurements in the past 70 years. The new idea is to increase ...... and able to avoid signal disturbance. The pressure and friction stress distribution results was as expected by the authors and showed good reproducibility, together with a proven agreement between recorded and simulated signals....... selected from a steady state with no disturbance from the material flow. The transducer was able to simultaneously measure both the normal pressure and the friction stress. An estimation of the coefficient of friction was accordingly performed. The new transducer works very well, it was seen to be robust...

  10. Celtic Stone Dynamics Revisited Using Dry Friction and Rolling Resistance

    Directory of Open Access Journals (Sweden)

    J. Awrejcewicz

    2012-01-01

    Full Text Available The integral model of dry friction components is built with assumption of classical Coulomb friction law and with specially developed model of normal stress distribution coupled with rolling resistance for elliptic contact shape. In order to avoid a necessity of numerical integration over the contact area at each the numerical simulation step, few versions of approximate model are developed and then tested numerically. In the numerical experiments the simulation results of the Celtic stone with the friction forces modelled by the use of approximants of different complexity (from no coupling between friction force and torque to the second order Padé approximation are compared to results obtained from model with friction approximated in the form of piecewise polynomial functions (based on the Taylor series with hertzian stress distribution. The coefficients of the corresponding approximate models are found by the use of optimization methods, like as in identification process using the real experiment data.

  11. Development of a Minimally Actuated Jumping-Rolling Robot

    Directory of Open Access Journals (Sweden)

    Thanhtam Ho

    2015-04-01

    Full Text Available This paper presents development of a hybrid mobile robot in order to take advantage of both rolling and jumping locomotion on the ground. According to the unique design of the mechanism, the robot is able to execute both jumping and rolling skilfully by using only one DC motor. Changing the centre of gravity enables rolling of the robot and storage of energy is utilized for jumping. Mechanism design and control logic are validated by computer simulation. Simulation results show that the robot can jump nearly 1.3 times its diameter and roll at the speed of 3.3 times its diameter per second.

  12. NORMAL PRESSURE AND FRICTION STRESS MEASUREMENT IN ROLLING PROCESSES

    DEFF Research Database (Denmark)

    Henningsen, Poul; Arentoft, Mogens; Lagergren, Jonas

    2005-01-01

    the output from the transducer, the friction stress and normal pressure in the contact zone can be determined. The new concept differs from existing pin designs by a lower disturbance of lubricant film and material flow and limited penetration of material between transducer and roll. Aluminum, cupper...

  13. Design and Rolling Analysis of a Novel Deformable Polyhedron Robot

    Directory of Open Access Journals (Sweden)

    Yaobin Tian

    2014-10-01

    Full Text Available In this paper, a new rolling robot is proposed. The mechanism of the robot consists of eight links with three degrees of freedom (DOFs. The shape of each link of the robot is an equilateral triangle. The robot realizes its direction switching function by deforming into different modes of planar parallelogram mechanisms (PPM. In any deterministic mode, the robot can roll on the ground. The motion of the robot is studied based on the kinematic and zero moment point (ZMP analyses. Though the robot has three DOFs, we show that it can realize flexible mobility via direction switching and rolling functions with two DOFs and one DOF, respectively. A prototype robot was manufactured. A series of simulations and experiments done using this prototype is reported, verifying the feasibility of the design.

  14. Effects of rolling friction on a spinning coin or disk

    Science.gov (United States)

    Cross, Rod

    2018-05-01

    Experimental and theoretical results are presented concerning the motion of a spinning disk on a horizontal surface. The disk precesses about a vertical axis while falling either quickly or slowly onto the surface depending on the coefficient of rolling friction. The rate of fall also depends on the offset distance, in the rolling direction, between the centre of mass and the line of action of the normal reaction force. Euler’s angular momentum equations are solved to obtain estimates of both the coefficient of friction and the offset distance for a 50.6 mm diameter brass disk spinning on three different surfaces. The fall times varied from about 3 s on P800 emery paper to about 30 s on glass.

  15. Study Friction Distribution during the Cold Rolling of Material by Matroll Software

    International Nuclear Information System (INIS)

    Abdollahi, H.; Dehghani, K.

    2007-01-01

    Rolling process is one of the most important ways of metal forming. Since the results of this process are almost finished product, therefore controlling the parameters affecting this process is very important in order to have cold rolling products with high quality. Among the parameters knowing the coefficient of friction within the roll gap is known as the most significant one. That is because other rolling parameters such as rolling force, pressure in the roll gap, forward slip, surface quality of sheet, and the life of work rolls are directly influenced by friction. On the other hand, in rolling calculation due to lake of a true amount for coefficient of friction a supposed value is considered for it. In this study, a new software (Matroll), is introduced which can determine the coefficient of friction (COF) and plot the friction hills for an industrial mill. Besides, based on rolling equations, it offers about 30 rolling parameters as outputs. Having the rolling characteristics as inputs, the software is able to calculate the coefficient of friction. Many rolling passes were performed on real industrial aluminum mill. The coefficient of friction was obtained for all passes. The results are in good agreement with the findings of the other researchers

  16. Frictional resistance of adiabatic two-phase flow in narrow rectangular duct under rolling conditions

    International Nuclear Information System (INIS)

    Xing, Dianchuan; Yan, Changqi; Sun, Licheng; Jin, Guangyuan; Tan, Sichao

    2013-01-01

    Highlights: ► Two-phase flow frictional resistance in narrow duct in rolling is studied. ► Frictional resistance behaviors in rolling are divided into three regions. ► Transient frictional pressure drop fluctuates synchronously with rolling motion. ► Conventional correlations are evaluated against experimental data in rolling motion. ► New correlation for transient frictional resistance in rolling motion is developed. - Abstract: Frictional resistance of air-water two-phase flow in a narrow rectangular duct subjected to rolling motion was investigated experimentally. Time-averaged and transient frictional pressure drop under rolling condition were compared with conventional correlation in laminar flow region (Re l l ⩽ 1400) and turbulent flow region (Re l > 1400) respectively. The result shows that, despite no influence on time-averaged frictional resistance, rolling motion does induce periodical fluctuation of the pressure drop in laminar and transition flow regions. Transient frictional pressure drop fluctuates synchronously with the rolling motion both in laminar and in transition flow region, while it is nearly invariable in turbulent flow region. The fluctuation amplitude of the Relative frictional pressure gradient decreases with the increasing of the superficial velocities. Lee and Lee (2002) correlation and Chisholm (1967) correlation could satisfactorily predict time-averaged frictional pressure drop under rolling conditions, whereas poorly predict the transient frictional pressure drop when it fluctuates periodically. A new correlation with better accuracy for predicting the transient frictional pressure drop in rolling motion is achieved by modifying the Chisholm (1967) correlation on the basis of analyzing the present experimental results with a great number of data points

  17. Transducer for measuring normal and friction stress in contact zone during rolling

    DEFF Research Database (Denmark)

    Henningsen, Poul; Wanheim, Tarras; Arentoft, Mogens

    2004-01-01

    , generating frictional stresses contrary to the direction of rolling. In a narrow area in the deformation zone, the velocity of the deformed material is equal to the velocity of the rolls. This area or line is named “neutral line”[2]. The position of the neutral line depends on friction, reduction ratio...

  18. Assessing the accuracy of different simplified frictional rolling contact algorithms

    Science.gov (United States)

    Vollebregt, E. A. H.; Iwnicki, S. D.; Xie, G.; Shackleton, P.

    2012-01-01

    This paper presents an approach for assessing the accuracy of different frictional rolling contact theories. The main characteristic of the approach is that it takes a statistically oriented view. This yields a better insight into the behaviour of the methods in diverse circumstances (varying contact patch ellipticities, mixed longitudinal, lateral and spin creepages) than is obtained when only a small number of (basic) circumstances are used in the comparison. The range of contact parameters that occur for realistic vehicles and tracks are assessed using simulations with the Vampire vehicle system dynamics (VSD) package. This shows that larger values for the spin creepage occur rather frequently. Based on this, our approach is applied to typical cases for which railway VSD packages are used. The results show that particularly the USETAB approach but also FASTSIM give considerably better results than the linear theory, Vermeulen-Johnson, Shen-Hedrick-Elkins and Polach methods, when compared with the 'complete theory' of the CONTACT program.

  19. Missile rolling tail brake torque system. [simulating bearing friction on canard controlled missiles

    Science.gov (United States)

    Davis, W. T. (Inventor)

    1984-01-01

    Apparatus for simulating varying levels of friction in the bearings of a free rolling tail afterbody on a canard-controlled missile to determine friction effects on aerodynamic control characteristics is described. A ring located between the missile body and the afterbody is utilized in a servo system to create varying levels of friction between the missile body and the afterbody to simulate bearing friction.

  20. Theoretical research on laminar friction resistance in tubes in rolling motion

    International Nuclear Information System (INIS)

    Yan Binghuo; Yu Lei; Yang Yanhua

    2010-01-01

    The model of laminar flow in tubes in rolling motion is established. The dimensionless correlation of velocity is derived, and the correlation of frictional resistance coefficient is also obtained. Of all the additional forces, only the tangential force effects on the flow. The effect of centrifugal and Coriolis forces on the flow is counteracted. The correlation of average frictional resistance coefficient is the same with that of no rolling motion. The effect of rolling motion on frictional resistance coefficient of laminar flow diminishes with the increase of Reynolds number. (authors)

  1. Variation of the Friction Coefficient for a Cylinder Rolling down an Inclined Board

    Science.gov (United States)

    Yan, Zixiang; Xia, Heming; Lan, Yueheng; Xiao, Jinghua

    2018-01-01

    A cylinder rolling down an inclined board is a commonly seen and interesting object to study and it is also easy to experiment with and model. Following what has become a popular practice, we use smartphones to measure the angular acceleration of a cylinder rolling down a plane of different inclining angles. The friction force deviates from the…

  2. Tribo-chemical behavior of eutectoid steel during rolling contact friction

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Y.; Cai, Z.B. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Peng, J.F. [Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China); Cao, B.B. [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Jin, X.S. [Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China); Zhu, M.H., E-mail: zhuminhao@swjtu.cn [Key Laboratory of Advanced Technologies of Materials, Ministry of Education, Southwest Jiaotong University, Chengdu 610031 (China); Tribology Research Institute, State Key Laboratory of Traction Power, Southwest Jiaotong University, Chengdu 610031 (China)

    2016-12-01

    Highlights: • Tribo-chemical behavior was investigated during rolling contact friction. • Tribo-film may weaken the absorptive ability of O/C atoms on the surface. • Tribo-film is related to a low friction coefficient at rolling friction condition. - Abstract: The tribo-chemical behavior of the eutectoid steel during rolling contact friction is investigated via scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy (XPS) and electron probe X-ray microanalysis. The worn surface is divided into three zones: matrix zone (without friction), tribo-film zone (formed during friction) and delamination zone (tribo-film spalling). The different chemical states of atoms between those three zones and the air were investigated using the XPS analysis. The results showed that the matrix zone is composed of Fe{sub 2}O{sub 3}, FeO and metallic Fe, while the tribo-film and delamination zones only contain Fe{sub 2}O{sub 3} and FeO. Where the tribo-film is formed, the absorptive ability of O and C atoms on the top 2–3 atomic layers is probably weakened, while the exposed fresh metal in the delamination zone tends to be continuously oxidized and form tribo-film. The tribo-chemical reaction in the delamination zone is more activated than that in the other two zones. The protective nature of the tribo-film probably maintains a low friction coefficient under rolling contact friction condition.

  3. Energy-based control for a biologically inspired hexapod robot with rolling locomotion

    Directory of Open Access Journals (Sweden)

    Takuma Nemoto

    2015-04-01

    Full Text Available This paper presents an approach to control rolling locomotion on the level ground with a biologically inspired hexapod robot. For controlling rolling locomotion, a controller which can compensate energy loss with rolling locomotion of the hexapod robot is designed based on its dynamic model. The dynamic model describes the rolling locomotion which is limited to planar one by an assumption that the hexapod robot does not fall down while rolling and influences due to collision and contact with the ground, and it is applied for computing the mechanical energy of the hexapod robot and a plant for a numerical simulation. The numerical simulation of the rolling locomotion on the level ground verifies the effectiveness of the proposed controller. The simulation results show that the hexapod robot can perform the rolling locomotion with the proposed controller. In conclusion, it is shown that the proposed control approach is effective in achieving the rolling locomotion on the level ground.

  4. Controlling Tensegrity Robots through Evolution using Friction based Actuation

    Science.gov (United States)

    Kothapalli, Tejasvi; Agogino, Adrian K.

    2017-01-01

    Traditional robotic structures have limitations in planetary exploration as their rigid structural joints are prone to damage in new and rough terrains. In contrast, robots based on tensegrity structures, composed of rods and tensile cables, offer a highly robust, lightweight, and energy efficient solution over traditional robots. In addition tensegrity robots can be highly configurable by rearranging their topology of rods, cables and motors. However, these highly configurable tensegrity robots pose a significant challenge for locomotion due to their complexity. This study investigates a control pattern for successful locomotion in tensegrity robots through an evolutionary algorithm. A twelve-rod hardware model is rapidly prototyped to utilize a new actuation method based on friction. A web-based physics simulation is created to model the twelve-rod tensegrity ball structure. Square-waves are used as control policies for the actuators of the tensegrity structure. Monte Carlo trials are run to find the most successful number of amplitudes for the square-wave control policy. From the results, an evolutionary algorithm is implemented to find the most optimized solution for locomotion of the twelve-rod tensegrity structure. The software pattern coupled with the new friction based actuation method can serve as the basis for highly efficient tensegrity robots in space exploration.

  5. Terrain Perception in a Shape Shifting Rolling-Crawling Robot

    Directory of Open Access Journals (Sweden)

    Fuchida Masataka

    2016-09-01

    Full Text Available Terrain perception greatly enhances the performance of robots, providing them with essential information on the nature of terrain being traversed. Several living beings in nature offer interesting inspirations which adopt different gait patterns according to nature of terrain. In this paper, we present a novel terrain perception system for our bioinspired robot, Scorpio, to classify the terrain based on visual features and autonomously choose appropriate locomotion mode. Our Scorpio robot is capable of crawling and rolling locomotion modes, mimicking Cebrenus Rechenburgi, a member of the huntsman spider family. Our terrain perception system uses Speeded Up Robust Feature (SURF description method along with color information. Feature extraction is followed by Bag of Word method (BoW and Support Vector Machine (SVM for terrain classification. Experiments were conducted with our Scorpio robot to establish the efficacy and validity of the proposed approach. In our experiments, we achieved a recognition accuracy of over 90% across four terrain types namely grass, gravel, wooden deck, and concrete.

  6. Friction control using ultrasonic oscillation for rolling-element linear-motion guide

    International Nuclear Information System (INIS)

    Oiwa, Takaaki

    2006-01-01

    This article reports a friction-control method for rolling-element linear-motion guides used for precision positioning. In general, static friction greater than dynamic friction generates stick-slip motion and diminishes the positioning accuracy. Two ultrasonic actuators excite both the rail and the carriage of the guide to give relative displacements to bearing surfaces. In order to effectively propagate the vibration over the entire rail without damping, the actuator drives at that frequency with a half wavelength corresponding to the distances between the rail mounting bolts. This also minimizes undesirable vibration of the machine structure. Moreover, the bearing surfaces of the carriage are resonated by a second ultrasonic actuator. The experiments using a force sensor showed that the static and dynamic friction forces were reduced by approximately 25% at any place on the 600-mm-long rail. Moreover, excitation only at very low velocity decreased the static friction peak

  7. Enhanced friction modeling for steady-state rolling tires

    NARCIS (Netherlands)

    Steen, van der R.

    2010-01-01

    Tire modeling is nowadays a necessary tool in the tire industry. Car manufacturers, governments and consumers demand better traction under all circumstances, less wear and more recently less noise and a lower rolling resistance. Therefore finite element analysis is adopted in the design process of

  8. Aspects Regarding Evaluation of Friction Effects in Robotic Systems

    Directory of Open Access Journals (Sweden)

    Florina-Carmen Ciornei

    2016-06-01

    Full Text Available The paper reveals both experimentally and by numerical simulation that modelling the dynamic behaviour of a robotic system that contains pairs where spin motion exists, finally leads towards nonlinear dynamical models. Despite the fact that academic monographs upon rigid mechanics use the hypothesis that spinning torque depends linearly on the normal force, a simple experiment contradicts this assumption. To this end, the motion of an axi-symmetric body making two contacts with dry friction is analyzed. The qualitative non-linearity of spinning torque on loading force dependence is validated in the end by the modelling of the test using dynamical simulation software.

  9. A substitute model of two-dimensional dry friction exposed to dither generated by rolling contact of wheel and rail

    Science.gov (United States)

    Piotrowski, Jerzy

    2012-10-01

    Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices.

  10. Theoretical Analysis of Unit Friction Force Working on the Metal Contact Surface with the Roll Change during Feedstock with Non-Uniform Temperature Distribution Rolling Process

    Directory of Open Access Journals (Sweden)

    Sygut P.

    2016-06-01

    Full Text Available The paper presents the results of theoretical studies influence of non-uniform temperature distribution along the feedstock length to the unit friction force working on the metal contact surface with the roll change during the round bars 70 mm in diameter continuous rolling process. This value is one of the major factors affecting the grooves wear during the rolling process. The studies were carried out based on the actual engineering data for 160 × 160 mm square cross-section feedstock of steel S355J0. Numerical modelling of the rolling process was performed using Forge2008®, a finite-element based computer program.

  11. Rolling Friction Torque in Ball-Race Contacts Operating in Mixed Lubrication Conditions

    Directory of Open Access Journals (Sweden)

    Mihaela Rodica D. Bălan

    2015-04-01

    Full Text Available Based on a theoretical model and an experimental methodology for defining the friction torque for lubricated conditions in a modified thrust ball bearing having only three balls, the authors experimentally investigated the influence of the lubricant parameter Λ on friction torque for mixed IVR (isoviscous rigid and EHL (elastohydrodynamic lubrication conditions. The experiments were conducted using ball diameters of 3 mm, 3.97 mm and 6.35 mm loaded at 0.125 N, 0.400 N and 0.633 N. Two oils of viscosity 0.08 Pa·s and 0.05 Pa·s were used and rotational speed was varied in the range 60–210 rpm to obtain a lubricant parameter Λ varying between 0.3 and 3.2. The experiments confirmed that the measured friction torque can be explained using hydrodynamic rolling force relationships respecting the transition from an IVR to an EHL lubrication regime.

  12. Immersed friction stir welding of ultrafine grained accumulative roll-bonded Al alloy

    International Nuclear Information System (INIS)

    Hosseini, M.; Danesh Manesh, H.

    2010-01-01

    In this research, ultrafine grained strips of commercial pure strain hardenable aluminum (AA1050) were produced by accumulative roll-bonding (ARB) technique. These strips were joined by friction stir welding (FSW) in immersed (underwater) and conventional (in-air) conditions to investigate the effect of the immersion method on the microstructure and mechanical properties of the joint, aiming to reduce the deterioration of the mechanical properties of the joint. Transmission electron microscopy and X-ray diffraction analyses were used to evaluate the microstructure, showing smaller grains and subgrains in the stir zone of the immersed FSW condition with respect to the conventional FSW method. The hardness and tensile properties of the immersed friction stir welded sample and ARBed base metal show more similarity compared to the conventional friction stir welded sample. Moreover, the aforementioned method can result in the enhancement of the superplasticity tendency of the material.

  13. Rudder Based Roll Control via host-computer of A Robotic Boat

    OpenAIRE

    Bao, Xinping; Yu, Zhenyu; Nonami, Kenzo

    2009-01-01

    Rudder based roll control of a small-sized robotic boat is a key technique for the devices on board to achieve good performance. This paper introduces a host-based robotic boat capable of performing basic movement operations. The course keeping and roll reduction are studied via rudder based method in simulations and sea trials. The boat dynamic model is built with the combination of mathematical analysis and system identification technique. A mixed sensitivity H control method design is sele...

  14. R3D3 : The Rolling Receptionist Robot with Double Dutch Dialogue

    NARCIS (Netherlands)

    Linssen, Jeroen; Theune, Mariet

    We discuss the design of R3D3, a rolling receptionist robot with the ability to conduct 'double Dutch dialogues': dialogues (in Dutch) that involve, besides a human user, both a robot and a virtual human. R3D3 is intended to assist people when they visit shops, museums, or other establishments by

  15. R3D3: The Rolling Receptionist Robot with Double Dutch Dialogue

    NARCIS (Netherlands)

    Linssen, Jeroen; Theune, Mariet

    We discuss the design of R3D3, a rolling receptionist robot with the ability to conduct 'double Dutch dialogues': dialogues (in Dutch) that involve, besides a human user, both a robot and a virtual human. R3D3 is intended to assist people when they visit shops, museums, or other establishments by

  16. Rudder Based Roll Control via host-computer of A Robotic Boat

    Directory of Open Access Journals (Sweden)

    Xinping Bao

    2009-03-01

    Full Text Available Rudder based roll control of a small-sized robotic boat is a key technique for the devices on board to achieve good performance. This paper introduces a host-based robotic boat capable of performing basic movement operations. The course keeping and roll reduction are studied via rudder based method in simulations and sea trials. The boat dynamic model is built with the combination of mathematical analysis and system identification technique. A mixed sensitivity H control method design is selected since yaw and roll motion are posed in different frequency domains. Computer simulations and experiments carried out show that successful results are achieved.

  17. Rudder Based Roll Control via Host-Computer of a Robotic Boat

    Directory of Open Access Journals (Sweden)

    Xinping Bao

    2009-03-01

    Full Text Available Rudder based roll control of a small-sized robotic boat is a key technique for the devices on board to achieve good performance. This paper introduces a host-based robotic boat capable of performing basic movement operations. The course keeping and roll reduction are studied via rudder based method in simulations and sea trials. The boat dynamic model is built with the combination of mathematical analysis and system identification technique. A mixed sensitivity H∞ control method design is selected since yaw and roll motion are posed in different frequency domains. Computer simulations and experiments carried out show that successful results are achieved.

  18. Development of a Dung Beetle Robot and Investigation of Its Dung-Rolling Behavior

    Directory of Open Access Journals (Sweden)

    Jen-Wei Wang

    2018-04-01

    Full Text Available In this study, a bio-inspired dung beetle robot was developed that emulated the dung rolling motion of the dung beetle. Dung beetles, which can roll objects up to 1000 times their own body weight, are one of the strongest insect species in the world. While the locomotion of many insects, such as cockroaches, inchworms, and butterflies, has been studied widely, the locomotion of dung beetles has rarely been given attention. Here, we report on the development of a dung beetle robot made specifically to investigate dung-rolling behavior and to determine and understand the underlying mechanism. Two versions of the robot were built, and the leg trajectories were carefully designed based on kinematic analysis. Cylinder and ball rolling experiments were conducted, and the results showed that the dung beetle robot could successfully and reliably roll objects. This further suggests that the dung beetle robot, with its current morphology, is capable of reliably rolling dung without the need for complex control strategies.

  19. FASTSIM2: a second-order accurate frictional rolling contact algorithm

    Science.gov (United States)

    Vollebregt, E. A. H.; Wilders, P.

    2011-01-01

    In this paper we consider the frictional (tangential) steady rolling contact problem. We confine ourselves to the simplified theory, instead of using full elastostatic theory, in order to be able to compute results fast, as needed for on-line application in vehicle system dynamics simulation packages. The FASTSIM algorithm is the leading technology in this field and is employed in all dominant railway vehicle system dynamics packages (VSD) in the world. The main contribution of this paper is a new version "FASTSIM2" of the FASTSIM algorithm, which is second-order accurate. This is relevant for VSD, because with the new algorithm 16 times less grid points are required for sufficiently accurate computations of the contact forces. The approach is based on new insights in the characteristics of the rolling contact problem when using the simplified theory, and on taking precise care of the contact conditions in the numerical integration scheme employed.

  20. A numerical study of the rolling friction between a microsphere and a substrate considering the adhesive effect

    International Nuclear Information System (INIS)

    Zhang, Yuyan; Wang, Xiaoli; Yang, Weixu; Li, Hanqing

    2016-01-01

    A numerical model of the rolling friction between a microsphere and a substrate is established by introducing the adhesion hysteresis between the front and rear sides of the contact region into Zhang’s adhesive contact model. Effects of the size ratio which is defined as the sphere radius divided by the equilibrium separation, relative amount of adhesion hysteresis and Tabor parameter on the dimensionless maximum rolling friction torque in the case of zero normal force are inspected, and the quantitative relationship between the maximum rolling friction torque and the normal force is achieved. Results indicate that due to adhesion hysteresis at microscale, the dimensionless maximum rolling friction torque at zero normal force is not zero, which not only increases with decreasing size ratio, showing clear size effects, but also increases with increasing relative amount of adhesion hysteresis and Tabor parameter. In addition, the maximum rolling friction torque at microscale presents a sublinear relationship with the normal force, and the exponent of the normal force is influenced by the size ratio, relative amount of adhesion hysteresis and Tabor parameter, which are remarkably different from the superlinear relationship at macroscale. (paper)

  1. GoQBot: a caterpillar-inspired soft-bodied rolling robot

    International Nuclear Information System (INIS)

    Lin, Huai-Ti; Trimmer, Barry; Leisk, Gary G

    2011-01-01

    Rolling locomotion using an external force such as gravity has evolved many times. However, some caterpillars can curl into a wheel and generate their own rolling momentum as part of an escape repertoire. This change in body conformation occurs well within 100 ms and generates a linear velocity over 0.2 m s -1 , making it one of the fastest self-propelled wheeling behaviors in nature. Inspired by this behavior, we construct a soft-bodied robot to explore the dynamics and control issues of ballistic rolling. This robot, called GoQBot, closely mimics caterpillar rolling. Analyzing the whole body kinematics and 2D ground reaction forces at the robot ground anchor reveals about 1G of acceleration and more than 200 rpm of angular velocity. As a novel rolling robot, GoQBot demonstrates how morphing can produce new modes of locomotion. Furthermore, mechanical coupling of the actuators improves body coordination without sensory feedback. Such coupling is intrinsic to soft-bodied animals because there are no joints to isolate muscle-generated movements. Finally, GoQBot provides an estimate of the mechanical power for caterpillar rolling that is comparable to that of a locust jump. How caterpillar musculature produces such power in such a short time is yet to be discovered.

  2. GoQBot: a caterpillar-inspired soft-bodied rolling robot

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Huai-Ti; Trimmer, Barry [Department of Biology, Tufts University, 163 Packard Avenue, Medford, MA 02155 (United States); Leisk, Gary G, E-mail: huaiti.lin@gmail.com, E-mail: gary.leisk@tufts.edu, E-mail: barry.trimmer@tufts.edu [Department of Mechanical Engineering, Tufts University, 200 College Avenue, Medford, MA 02155 (United States)

    2011-06-15

    Rolling locomotion using an external force such as gravity has evolved many times. However, some caterpillars can curl into a wheel and generate their own rolling momentum as part of an escape repertoire. This change in body conformation occurs well within 100 ms and generates a linear velocity over 0.2 m s{sup -1}, making it one of the fastest self-propelled wheeling behaviors in nature. Inspired by this behavior, we construct a soft-bodied robot to explore the dynamics and control issues of ballistic rolling. This robot, called GoQBot, closely mimics caterpillar rolling. Analyzing the whole body kinematics and 2D ground reaction forces at the robot ground anchor reveals about 1G of acceleration and more than 200 rpm of angular velocity. As a novel rolling robot, GoQBot demonstrates how morphing can produce new modes of locomotion. Furthermore, mechanical coupling of the actuators improves body coordination without sensory feedback. Such coupling is intrinsic to soft-bodied animals because there are no joints to isolate muscle-generated movements. Finally, GoQBot provides an estimate of the mechanical power for caterpillar rolling that is comparable to that of a locust jump. How caterpillar musculature produces such power in such a short time is yet to be discovered.

  3. Estimation of coefficient of rolling friction by the evolvent pendulum method

    Science.gov (United States)

    Alaci, S.; Ciornei, F. C.; Ciogole, A.; Ciornei, M. C.

    2017-05-01

    The paper presents a method for finding the coefficient of rolling friction using an evolvent pendulum. The pendulum consists in a fixed cylindrical body and a mobile body presenting a plane surface in contact with a cylindrical surface. The mobile body is placed over the fixed one in an equilibrium state; after applying a small impulse, the mobile body oscillates. The motion of the body is video recorded and afterwards the movie is analyzed by frames and the decrease with time of angular amplitude of the pendulum is found. The equation of motion is established for oscillations of the mobile body. The equation of motion, differential nonlinear, is integrated by Runge-Kutta method. Imposing the same damping both to model’s solution and to theoretical model, the value of coefficient of rolling friction is obtained. The last part of the paper presents results for actual pairs of materials. The main advantage of the method is the fact that the dimensions of contact regions are small, of order a few millimeters, and thus is substantially reduced the possibility of variation of mechanical characteristic for the two surfaces.

  4. Internal friction in cold-rolled metallic glasses Cu50Ti50 and Ni78Si8B14

    International Nuclear Information System (INIS)

    Zolotukhin, I.V.; Khonik, V.A.; Ryabtseva, T.N.; Belyavskii, V.I.

    1989-01-01

    The influence of cold rolling on the low temperature (30 to 300 K) internal friction of metallic glasses Cu 50 Ti 50 and Ni 78 Si 8 B 14 is investigated. It is shown that cold rolling of both metallic glasses up to 2 to 6% results in the appearance of a high relaxation damping peak around 260 to 280 K. The internal friction background below the peak shows a strong amplitude dependence. In highly predeformed specimens (∼ 16%) the internal friction peak is absent. Electron irradiation (2 MeV, 10 19 cm -2 ) leads to the suppression of the deformation-induced internal friction peak. The results are interpreted in the framework of the dislocation models of plastic flow of metallic glasses. (author)

  5. Vehicle Velocity and Roll Angle Estimation with Road and Friction Adaptation for Four-Wheel Independent Drive Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Linhui Zhao

    2014-01-01

    Full Text Available Vehicle velocity and roll angle are important information for active safety control systems of four-wheel independent drive electric vehicle. In order to obtain robustness estimation of vehicle velocity and roll angle, a novel method is proposed based on vehicle dynamics and the measurement information provided by the sensors equipped in modern cars. The method is robust with respect to different road and friction conditions. Firstly, the dynamic characteristics of four-wheel independent drive electric vehicle are analyzed, and a four-degree-of-freedom nonlinear dynamic model of vehicle and a tire longitudinal dynamic equation are established. The relationship between the longitudinal and lateral friction forces is derived based on Dugoff tire model. The unknown input reconstruction technique of sliding mode observer is used to achieve longitudinal tire friction force estimation. A simple observer is designed for the estimation of the roll angle of the vehicle. And then using the relationship, the estimated longitudinal friction forces and roll angle, a sliding mode observer for vehicle velocity estimation is provided, which does not need to know the tire-road friction coefficient and road angles. Finally, the proposed method is evaluated experimentally under a variety of maneuvers and road conditions.

  6. SU-F-P-31: Dosimetric Effects of Roll and Pitch Corrections Using Robotic Table

    Energy Technology Data Exchange (ETDEWEB)

    Mamalui, M; Su, Z; Flampouri, S; Li, Z [University of Florida Proton Therapy Institute, Jacksonville, FL (United States)

    2016-06-15

    Purpose: To quantify the dosimetric effect of roll and pitch corrections being performed by two types of robotic tables available at our institution: BrainLabTM 5DOF robotic table installed at VERO (BrainLab&MHI) dedicated SBRT linear accelerator and 6DOF robotic couch by IBA Proton Therapy with QFixTM couch top. Methods: Planning study used a thorax phantom (CIRSTM), scanned at 4DCT protocol; targets (IGTV, PTV) were determined according to the institutional lung site-specific standards. 12 CT sets were generated with Pitch and Roll angles ranging from −4 to +4 degrees each. 2 table tops were placed onto the scans according to the modality-specific patient treatment workflows. The pitched/rolled CT sets were fused to the original CT scan and the verification treatment plans were generated (12 photon SBRT plans and 12 proton conventional fractionation lung plans). Then the CT sets were fused again to simulate the effect of patient roll/pitch corrections by the robotic table. DVH sets were evaluated for all cases. Results: The effect of not correcting the phantom position for roll/pitch in photon SBRT cases was reducing the target coverage by 2% as maximum; correcting the positional errors by robotic table varied the target coverage within 0.7%. in case of proton treatment, not correcting the phantom position led to the coverage loss up to 4%, applying the corrections using robotic table reduced the coverage variation to less than 2% for PTV and within 1% for IGTV. Conclusion: correcting the patient position by using robotic tables is highly preferable, despite the small dosimetric changes introduced by the devices.

  7. SU-F-P-31: Dosimetric Effects of Roll and Pitch Corrections Using Robotic Table

    International Nuclear Information System (INIS)

    Mamalui, M; Su, Z; Flampouri, S; Li, Z

    2016-01-01

    Purpose: To quantify the dosimetric effect of roll and pitch corrections being performed by two types of robotic tables available at our institution: BrainLabTM 5DOF robotic table installed at VERO (BrainLab&MHI) dedicated SBRT linear accelerator and 6DOF robotic couch by IBA Proton Therapy with QFixTM couch top. Methods: Planning study used a thorax phantom (CIRSTM), scanned at 4DCT protocol; targets (IGTV, PTV) were determined according to the institutional lung site-specific standards. 12 CT sets were generated with Pitch and Roll angles ranging from −4 to +4 degrees each. 2 table tops were placed onto the scans according to the modality-specific patient treatment workflows. The pitched/rolled CT sets were fused to the original CT scan and the verification treatment plans were generated (12 photon SBRT plans and 12 proton conventional fractionation lung plans). Then the CT sets were fused again to simulate the effect of patient roll/pitch corrections by the robotic table. DVH sets were evaluated for all cases. Results: The effect of not correcting the phantom position for roll/pitch in photon SBRT cases was reducing the target coverage by 2% as maximum; correcting the positional errors by robotic table varied the target coverage within 0.7%. in case of proton treatment, not correcting the phantom position led to the coverage loss up to 4%, applying the corrections using robotic table reduced the coverage variation to less than 2% for PTV and within 1% for IGTV. Conclusion: correcting the patient position by using robotic tables is highly preferable, despite the small dosimetric changes introduced by the devices.

  8. METHOD OF THE DRIVE POWER DETERMINATION OF THE MECHANISMS OF THE BRIDGE CRANE MOVEMENT CONSIDERING THE ROLLING FRICTION

    Directory of Open Access Journals (Sweden)

    V. M. Bohomaz

    2015-08-01

    Full Text Available Purpose. The value of drive resistance to its movement is the main parameter at calculating the drive power of bridge crane. The value of the wheel rolling friction on the rails is one of the important parts of the resistance to movement. It is necessary to determine the dependence of static (dynamic quantities of resistance to the bridge crane movement on a straight section of the track from the position of the bogie in the span, and explore the influence of the wheel flanges resistance for wear. Methodology. Using the analytical dependences for determining the rolling friction coefficient, that depends on the size of the half-width of the contact between the wheel and rail, the improved method for calculating the required drive power of the crane was proposed. Findings. With the proposed method of power calculation the characteristic curve of the crane wheel loads, the coefficient of rolling friction of the wheels and the crane resistance to movement from the position of the bogie on span were built. In the result of graphs analysis it was found that the engine power, obtained by the proposed method is higher than the recommended by the existing standards. The more precise formula for determining the total coefficient of sliding friction that takes into account the friction of wheel flanges on the rail is given. The characteristic curves of such coefficient of friction and the total resistance to movement of the position of the crane bogie were built. Originality. The scientists proposed an improved method of determining the required engine power of bridge crane, which takes into account the effect of rolling friction of the wheels on the rails and the bogie in the span. The improved formula for determining the coefficient of friction that takes into account the friction wheel flanges of the rail was given. The characteristic curve of this coefficient of friction and the total resistance movement of crane from the position of the crane bogie

  9. Testbed of a novel robotic pitch-roll wrist parameter identification

    DEFF Research Database (Denmark)

    Ma, Xiao Qing; Chopra, Vikram; Angeles, Jorge

    2010-01-01

    The paper reports work in progress on the development of an innovative gearless pitch-roll wrist (PRW)for robotic applications. The PRW bears the morphology of a bevel-gear differential, its novelty lying in the absence of gears. Indeed, the PRW motivating this study is based on cams and rollers,...

  10. Controller tuning based on optimization algorithms of a novel spherical rolling robot

    Energy Technology Data Exchange (ETDEWEB)

    Sadegjian, Rasou [Dept. of Electrical, Biomedical, and Mechatronics Engineering, Qazvin Branch, Islamic Azad University, QazvinI (Iran, Islamic Republic of); Masouleh, Mehdi Tale [Human and Robot Interaction Laboratory, Faculty of New Sciences and Technologies, University of Tehran, Tehran (Iran, Islamic Republic of)

    2016-11-15

    This study presents the construction process of a novel spherical rolling robot and control strategies that are used to improve robot locomotion. The proposed robot drive mechanism is constructed based on a combination of the pendulum and wheel drive mechanisms. The control model of the proposed robot is developed, and the state space model is calculated based on the obtained control model. Two control strategies are defined to improve the synchronization performance of the proposed robot motors. The proportional-derivative and proportional-integral-derivative controllers are designed based on the pole placement method. The proportional-integral-derivative controller leads to a better step response than the proportional-derivative controller. The controller parameters are tuned with genetic and differential evaluation algorithms. The proportional-integral-derivative controller which is tuned based on the differential evaluation algorithm leads to a better step response than the proportional-integral-derivative controller that is tuned based on genetic algorithm. Fuzzy logics are used to reduce the robot drive mechanism motors synchronizing process time to the end of achieving a high-performance controller. The experimental implementation results of fuzzy-proportional-integral-derivative on the proposed spherical rolling robot resulted in a desirable synchronizing performance in a short time.

  11. Controller tuning based on optimization algorithms of a novel spherical rolling robot

    International Nuclear Information System (INIS)

    Sadegjian, Rasou; Masouleh, Mehdi Tale

    2016-01-01

    This study presents the construction process of a novel spherical rolling robot and control strategies that are used to improve robot locomotion. The proposed robot drive mechanism is constructed based on a combination of the pendulum and wheel drive mechanisms. The control model of the proposed robot is developed, and the state space model is calculated based on the obtained control model. Two control strategies are defined to improve the synchronization performance of the proposed robot motors. The proportional-derivative and proportional-integral-derivative controllers are designed based on the pole placement method. The proportional-integral-derivative controller leads to a better step response than the proportional-derivative controller. The controller parameters are tuned with genetic and differential evaluation algorithms. The proportional-integral-derivative controller which is tuned based on the differential evaluation algorithm leads to a better step response than the proportional-integral-derivative controller that is tuned based on genetic algorithm. Fuzzy logics are used to reduce the robot drive mechanism motors synchronizing process time to the end of achieving a high-performance controller. The experimental implementation results of fuzzy-proportional-integral-derivative on the proposed spherical rolling robot resulted in a desirable synchronizing performance in a short time

  12. BiLBIQ A Biologically Inspired Robot with Walking and Rolling Locomotion

    CERN Document Server

    King, Ralf Simon

    2013-01-01

    The book ‘BiLBIQ: A biologically inspired Robot with walking and rolling locomotion’ deals with implementing a locomotion behavior observed in the biological archetype Cebrennus villosus to a robot prototype whose structural design needs to be developed.   The biological sample is investigated as far as possible and compared to other evolutional solutions within the framework of nature’s inventions. Current achievements in robotics are examined and evaluated for their relation and relevance to the robot prototype in question. An overview of what is state of the art in actuation ensures the choice of the hardware available and most suitable for this project. Through a constant consideration of the achievement of two fundamentally different ways of locomotion with one and the same structure, a robot design is developed and constructed taking hardware constraints into account. The development of a special leg structure that needs to resemble and replace body elements of the biological archetype is a speci...

  13. Standard test method for measuring rolling friction characteristics of a spherical shape on a flat horizontal plane

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the use of an angled launch ramp to initiate rolling of a sphere or nearly spherical shape on a flat horizontal surface to determine the rolling friction characteristics of a given spherical shape on a given surface. 1.1.1 Steel balls on a surface plate were used in interlaboratory tests (see Appendix X1). Golf balls on a green, soccer and lacrosse balls on playing surfaces, bowling balls on an a lane, basketballs on hardwood, and marbles on composite surface were tested in the development of this test method, but the test applies to any sphere rolling on any flat horizontal surface. 1.1.2 The rolling friction of spheres on horizontal surfaces is affected by the spherical shape’s stiffness, radius of curvature, surface texture, films on the surface, the nature of the counterface surface; there are many factors to consider. This test method takes all of these factors into consideration. The spherical shape of interest is rolled on the surface of interest using a standard ramp to...

  14. Three-dimensional construction and omni-directional rolling analysis of a novel frame-like lattice modular robot

    Science.gov (United States)

    Ding, Wan; Wu, Jianxu; Yao, Yan'an

    2015-07-01

    Lattice modular robots possess diversity actuation methods, such as electric telescopic rod, gear rack, magnet, robot arm, etc. The researches on lattice modular robots mainly focus on their hardware descriptions and reconfiguration algorithms. Meanwhile, their design architectures and actuation methods perform slow telescopic and moving speeds, relative low actuation force verse weight ratio, and without internal space to carry objects. To improve the mechanical performance and reveal the locomotion and reconfiguration binary essences of the lattice modular robots, a novel cube-shaped, frame-like, pneumatic-based reconfigurable robot module called pneumatic expandable cube(PE-Cube) is proposed. The three-dimensional(3D) expanding construction and omni-directional rolling analysis of the constructed robots are the main focuses. The PE-Cube with three degrees of freedom(DoFs) is assembled by replacing the twelve edges of a cube with pneumatic cylinders. The proposed symmetric construction condition makes the constructed robots possess the same properties in each supporting state, and a binary control strategy cooperated with binary actuator(pneumatic cylinder) is directly adopted to control the PE-Cube. Taking an eight PE-Cube modules' construction as example, its dynamic rolling simulation, static rolling condition, and turning gait are illustrated and discussed. To testify telescopic synchronization, respond speed, locomotion feasibility, and repeatability and reliability of hardware system, an experimental pneumatic-based robotic system is built and the rolling and turning experiments of the eight PE-Cube modules' construction are carried out. As an extension, the locomotion feasibility of a thirty-two PE-Cube modules' construction is analyzed and proved, including dynamic rolling simulation, static rolling condition, and dynamic analysis in free tipping process. The proposed PE-Cube module, construction method, and locomotion analysis enrich the family of the

  15. Investigating the role of sliding friction in rolling motion: a teaching sequence based on experiments and simulations

    Science.gov (United States)

    De Ambrosis, Anna; Malgieri, Massimiliano; Mascheretti, Paolo; Onorato, Pasquale

    2015-05-01

    We designed a teaching-learning sequence on rolling motion, rooted in previous research about student conceptions, and proposing an educational reconstruction strongly centred on the role of friction in different cases of rolling. A series of experiments based on video analysis is used to highlight selected key concepts and to motivate students in their exploration of the topic; and interactive simulations, which can be modified on the fly by students to model different physical situations, are used to stimulate autonomous investigation in enquiry activities. The activity sequence was designed for students on introductory physics courses and was tested with a group of student teachers. Comparisons between pre- and post-tests, and between our results and those reported in the literature, indicate that students’ understanding of rolling motion improved markedly and some typical difficulties were overcome.

  16. Fault Diagnosis of a Reconfigurable Crawling–Rolling Robot Based on Support Vector Machines

    Directory of Open Access Journals (Sweden)

    Karthikeyan Elangovan

    2017-10-01

    Full Text Available As robots begin to perform jobs autonomously, with minimal or no human intervention, a new challenge arises: robots also need to autonomously detect errors and recover from faults. In this paper, we present a Support Vector Machine (SVM-based fault diagnosis system for a bio-inspired reconfigurable robot named Scorpio. The diagnosis system needs to detect and classify faults while Scorpio uses its crawling and rolling locomotion modes. Specifically, we classify between faulty and non-faulty conditions by analyzing onboard Inertial Measurement Unit (IMU sensor data. The data capture nine different locomotion gaits, which include rolling and crawling modes, at three different speeds. Statistical methods are applied to extract features and to reduce the dimensionality of original IMU sensor data features. These statistical features were given as inputs for training and testing. Additionally, the c-Support Vector Classification (c-SVC and nu-SVC models of SVM, and their fault classification accuracies, were compared. The results show that the proposed SVM approach can be used to autonomously diagnose locomotion gait faults while the reconfigurable robot is in operation.

  17. A novel traveling wave piezoelectric actuated tracked mobile robot utilizing friction effect

    Science.gov (United States)

    Wang, Liang; Shu, Chengyou; Jin, Jiamei; Zhang, Jianhui

    2017-03-01

    A novel traveling wave piezoelectric-actuated tracked mobile robot with potential application to robotic rovers was proposed and investigated in this study. The proposed tracked mobile robot is composed of a parallelogram-frame-structure piezoelectric transducer with four rings and a metal track. Utilizing the converse piezoelectric and friction effects, traveling waves were propagated in the rings and then the metal track was actuated by the piezoelectric transducer. Compared with traditional tracked mechanisms, the proposed tracked mobile robot has a simpler and more compact structure without lubricant, which eliminates the problem of lubricant volatilization and deflation, thus, it could be operated in the vacuum environment. Dynamic characteristics were simulated and measured to reveal the mechanism of actuating track of the piezoelectric transducer. Experimental investigations of the traveling wave piezoelectric-actuated tracked mobile robot were then carried out, and the results indicated that the robot prototype with a pair of exciting voltages of 460 Vpp is able to achieve a maximum velocity of 57 mm s-1 moving on the foam plate and possesses the obstacle crossing capability with a maximum height of 27 mm. The proposed tracked mobile robot exhibits potential to be the driving system of robotic rovers.

  18. Investigating Corrosion, Wear Resistance and Friction of AA5454-O Series after its Severe Deformation by Rolling

    Directory of Open Access Journals (Sweden)

    Sinan SEZEK

    2017-02-01

    Full Text Available AA5454-O is an easily wrought, or in other words, a ductile aluminium alloy, however, its mechanical properties are inferior as compared to those of other alloys. The change taking place in corrosion resistance of AA5454-O alloy as a result of its severe plastic deformation (SPD by rolling has been investigated in this study. It has been observed that significant changes occurred in abrasion wear and corrosion resistances of AA5454-O alloy, which was severely deformed up to 80 % by rolling process. Corrosion resistance of the alloy that was severely deformed by rolling has increased. The effect of deformation rate on corrosion has been investigated by applying potentiodynamic test whereas on the other hand such change has been evidenced also through corrosion test. It has been observed that friction coefficient of severely deformed AA5454-O alloy varied by around 10 %, and that, associated with such change, its wear resistance also increased considerably. It has been determined that, as a result of severe deformation by rolling, hardness values rose in areas where the alloy was in contact with rolling surface. In this study, wear resistance of severely deformed alloy has been investigated as well. It has been observed that deformation value contributed positively to the increase in wear resistance.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14650

  19. Use of spring-roll EAP actuator applied as end-effector of a hyper-redundant robot

    Science.gov (United States)

    Errico, Gianmarco; Fava, Victor; Resta, Ferruccio; Ripamonti, Francesco

    2015-04-01

    This paper presents a hyper-redundant continuous robot used to perform work in places which humans can not reach. This type of robot is generally a bio-inspired solution, it is composed by a lot of flexible segments driven by multiple actuators and its dynamics is described by a lot degrees of freedom. In this paper a model composed of some rigid links connected to each other by revolution joint is presented. In each link a torsional spring is added in order to simulate the resistant torque between the links and the interactions among the cables and the robot during the relative rotation. Moreover a type of EAP actuator, called spring roll, is used as the end-effector of the robot. Through a suitable sensor, such as a camera, the spring roll allows to track a target and it closes the control loop on the robot to follow it.

  20. Influence of the Friction Coefficient on the Trajectory Performance for a Car-Like Robot

    Directory of Open Access Journals (Sweden)

    Francisco Valero

    2017-01-01

    Full Text Available A collision-free trajectory planner for a car-like mobile robot moving in complex environments is introduced and the influence of the coefficient of friction on important working parameters is analyzed. The proposed planner takes into account not only the dynamic capabilities of the robot but also the behaviour of the tire. This planner is based on sequential quadratic programming algorithms and the normalized time method. Different values for the coefficient of friction have been taken following a normal Gaussian distribution to see its influence on the working parameters. The algorithm has been applied to several examples and the results show that computation times are compatible with real-time work, so the authors call them efficient generated trajectories as they avoid collisions. Besides, working parameters such as the minimum trajectory time, the maximum vehicle speed, computational time, and consumed energy have been monitored and some conclusions have been reached.

  1. Experimental Validation of Strategy for the Inverse Estimation of Mechanical Properties and Coefficient of Friction in Flat Rolling

    Science.gov (United States)

    Yadav, Vinod; Singh, Arbind Kumar; Dixit, Uday Shanker

    2017-08-01

    Flat rolling is one of the most widely used metal forming processes. For proper control and optimization of the process, modelling of the process is essential. Modelling of the process requires input data about material properties and friction. In batch production mode of rolling with newer materials, it may be difficult to determine the input parameters offline. In view of it, in the present work, a methodology to determine these parameters online by the measurement of exit temperature and slip is verified experimentally. It is observed that the inverse prediction of input parameters could be done with a reasonable accuracy. It was also assessed experimentally that there is a correlation between micro-hardness and flow stress of the material; however the correlation between surface roughness and reduction is not that obvious.

  2. Effect of the cold-rolling parameters and the yield strength of the strip material on the friction stresses in a deformation zone

    Science.gov (United States)

    Garber, E. A.; Yagudin, I. V.; Ermilov, V. V.; Traino, A. I.

    2009-10-01

    The reliability of the methods of determining the friction coefficient is analyzed, since the friction stresses in the deformation zone during cold rolling significantly affect the quality of cold-rolled sheets and the energy consumption. The well-known experimental data and empirical dependences are shown to contradict each other, and the statistical assurance of these dependences is absent. A database on the interrelated technological and energy-force parameters of a five-stand cold-rolling mill, which includes a wide range of steel grades and strip sizes and shapes, is analyzed. Regression analysis is used to obtain a statistically reliable regression dependence of the friction coefficient in the deformation zone on the most significant technological parameters. The application of this dependence decreases the error of energy-force calculations by more than two times.

  3. A Microstructural Evaluation of Friction Stir Welded 7075 Aluminum Rolled Plate Heat Treated to the Semi-Solid State

    Directory of Open Access Journals (Sweden)

    Ava Azadi Chegeni

    2018-01-01

    Full Text Available Two rolled plates of 7075 aluminum alloy were used as starting material. The plates were welded using a simultaneous double-sided friction stir welding (FSW process. One way of obtaining feedstock materials for Semi-solid processing or thixoforming is via deformation routes followed by partial melting in the semi-solid state. As both the base plate materials and the friction weld area have undergone extensive deformation specimens were subjected to a post welding heat-treatment in the semi-solid range at a temperature of 628 °C, for 3 min in order to observe the induced microstructural changes. A comparison between the microstructural evolution and mechanical properties of friction stir welded plates was performed before and after the heat-treatment in the Base Metal (BM, the Heat Affected Zone (HAZ, the Thermomechanically Affected Zone (TMAZ and the Nugget Zone (NZ using optical microscopy, Scanning Electron microscopy (SEM and Vickers hardness tests. The results revealed that an extremely fine-grained structure, obtained in the NZ after FSW, resulted in a rise of hardness from the BM to the NZ. Furthermore, post welding heat-treatment in the semi-solid state gave rise to a consistent morphology throughout the material which was similar to microstructures obtained by the thixoforming process. Moreover, a drop of hardness was observed after heat treatment in all regions as compared to that in the welded microstructure.

  4. Low friction slip-rolling contacts. Influences of alternative steels, high performance thin film coatings and lubricants

    Energy Technology Data Exchange (ETDEWEB)

    Scholz, Christian

    2013-02-01

    Due to the growing environmental awareness worldwide, containment provisions for CO{sub 2} emissions in mobility systems and increasing performance requirements the demands on mechanical systems and their materials continuously rise. These high demands require the implementation of new technical approaches, for example of light-weight strategies in automotive powertrains, and directly raise questions about the suitability of the most promising technical solution. Two basic parameters, the surface hardness of the tooth flanks and the core fatigue strength of the tooth root, illustrate exemplarily increasing demands on material grades used for gear wheels in automotive powertrains. In addition to light-weight strategies, a reduction in friction and an increase of the fatigue lifetime are two other major development directions to strive the mentioned targets. It is clear that any kind of solution must show an equal application profile, preferably an improvement, compared to the state-of-the-art solutions. For tribological systems, the following paths may offer lower friction and higher load carrying capabilities: 1. Alternative base oils and additives (such as esters, polyglycols), 2. Thin film coatings (e.g. DLC) and/or 3. Novel steel metallurgies. In previous investigations on the slip-rolling resistance of thin film coatings (a-C, ta-C, Zr(C,N)) the substrates were mainly made of the bearing steels 100Cr6H and Cronidur 30. Applying contact pressures of up to P{sub 0max} = 2.9 GPa (F{sub N} = 2,000 N), the samples were tested up to 10 million load cycles in endurance tests. The aim of the present work is to broaden the research by varying the input parameters. Newly developed engine oil mixtures, high performance thin film coatings and alternative steel solutions are intensively investigated in highly stressed slip-rolling contacts at lubricant temperatures of 120 C. Specifically, in using new steel metallurgies, i.e. the high toughness and high strength steels V300

  5. New insights into the short pitch corrugation development enigma based on 3D-FE dynamic vehicle-track coupled modelling in frictional rolling contact

    NARCIS (Netherlands)

    Li, S.; Li, Z.; Nunez Vicencio, Alfredo; Dollevoet, R.P.B.J.

    2017-01-01

    A three-dimensional (3D) finite element (FE) dynamic frictional rolling contact model is presented for the study of short pitch corrugation that considers direct and instantaneous coupling between the contact mechanics and the structural dynamics in a vehicle-track system. In this study, we examine

  6. Experimental and numerical study of friction and braking characteristics of rolling tires

    NARCIS (Netherlands)

    Steen, R. van der; Lopez, I.; Nijmeijer, H.; Schmeitz, A.J.C.; Bruijn, B. de

    2011-01-01

    Throughout the tire industry, virtual testing has been widely adopted in the design process. Both static deformation and dynamic response of the tire rolling on the road must be accurately predicted to evaluate the handling performance of a tire. Unfortunately, experimental characterization of

  7. Towards fast, reliable, and manufacturable DEAs: miniaturized motor and Rupert the rolling robot

    Science.gov (United States)

    Rosset, Samuel; Shea, Herbert

    2015-04-01

    Dielectric elastomer transducers (DETs) are known for their large strains, low mass and high compliance, making them very attractive for a broad range of applications, from soft robotics to tuneable optics, or energy harvesting. However, 15 years after the first major paper in the field, commercial applications of the technology are still scarce, owing to high driving voltages, short lifetimes, slow response speed, viscoelastic drift, and no optimal solution for the compliant electrodes. At the EPFL's Microsystems for Space Technologies laboratory, we have been working on the miniaturization and manufacturability of DETs for the past 10 years. In the frame of this talk, we present our fabrication processes for high quality thin-_lm silicone membranes, and for patterning compliant electrodes on the sub mm-scale. We use either implantation of gold nano-clusters through a mask, or pad-printing of conductive rubber to precisely shape the electrodes on the dielectric membrane. Our electrodes are compliant, time stable and present strong adhesion to the membrane. The combination of low mechanical- loss elastomers with robust and precisely-defined electrodes allows for the fabrication of very fast actuators that exhibit a long lifetime. We present different applications of our DET fabrication process, such as a soft tuneable lens with a settling time smaller than 175 microseconds, a motor spinning at 1500 rpm, and a self-commutating rolling robot.

  8. Experimental Investigation of Friction Effect on Liner Model Rolling Bearings for Large Diameter Thrust Bearing Design

    Directory of Open Access Journals (Sweden)

    S. Babu

    2012-12-01

    Full Text Available Studying friction coefficient has significant importance, especially when dealing with high load and temperature applications that have frequent starting and stopping points. Towards that, two sets of angular contact Linear Model Mockup Bearings (LMMB were designed and fabricated. This linear model assembly was made up of high precision, grounded raceways (AISI 4140 and commercially purchased balls (AISI 52100. The experimental studies were carried out by placing different number of balls between the raceways under different loads at dry lubricating condition. The static friction coefficients were measured using two different experiments: viz gravitation-based experiment and direct linear force measurement experiment. And Digital Image Correlation (DIC technique was used to find the stiffness of LMMB set.

  9. Friction

    Science.gov (United States)

    Matsuo, Yoshihiro; Clarke, Daryl D.; Ozeki, Shinichi

    Friction materials such as disk pads, brake linings, and clutch facings are widely used for automotive applications. Friction materials function during braking due to frictional resistance that transforms kinetic energy into thermal energy. There has been a rudimentary evolution, from materials like leather or wood to asbestos fabric or asbestos fabric saturated with various resins such as asphalt or resin combined with pitch. These efforts were further developed by the use of woven asbestos material saturated by either rubber solution or liquid resin binder and functioned as an internal expanding brake, similar to brake lining system. The role of asbestos continued through the use of chopped asbestos saturated by rubber, but none was entirely successful due to the poor rubber heat resistance required for increased speeds and heavy gearing demands of the automobile industry. The use of phenolic resins as binder for asbestos friction materials provided the necessary thermal resistance and performance characteristics. Thus, the utility of asbestos as the main friction component, for over 100 years, has been significantly reduced in friction materials due to asbestos identity as a carcinogen. Steel and other fibrous components have displaced asbestos in disk pads. Currently, non-asbestos organics are the predominate friction material. Phenolic resins continue to be the preferred binder, and increased amounts are necessary to meet the requirements of highly functional asbestos-free disk pads for the automotive industry. With annual automobile production exceeding 70 million vehicles and additional automobile production occurring in developing countries worldwide and increasing yearly, the amount of phenolic resin for friction material is also increasing (Fig. 14.1). Fig. 14.1 Worldwide commercial vehicle production In recent years, increased fuel efficiency of passenger car is required due to the CO2 emission issue. One of the solutions to improve fuel efficiency is to

  10. A simple running model with rolling contact and its role as a template for dynamic locomotion on a hexapod robot

    International Nuclear Information System (INIS)

    Huang, Ke-Jung; Huang, Chun-Kai; Lin, Pei-Chun

    2014-01-01

    We report on the development of a robot’s dynamic locomotion based on a template which fits the robot’s natural dynamics. The developed template is a low degree-of-freedom planar model for running with rolling contact, which we call rolling spring loaded inverted pendulum (R-SLIP). Originating from a reduced-order model of the RHex-style robot with compliant circular legs, the R-SLIP model also acts as the template for general dynamic running. The model has a torsional spring and a large circular arc as the distributed foot, so during locomotion it rolls on the ground with varied equivalent linear stiffness. This differs from the well-known spring loaded inverted pendulum (SLIP) model with fixed stiffness and ground contact points. Through dimensionless steps-to-fall and return map analysis, within a wide range of parameter spaces, the R-SLIP model is revealed to have self-stable gaits and a larger stability region than that of the SLIP model. The R-SLIP model is then embedded as the reduced-order ‘template’ in a more complex ‘anchor’, the RHex-style robot, via various mapping definitions between the template and the anchor. Experimental validation confirms that by merely deploying the stable running gaits of the R-SLIP model on the empirical robot with simple open-loop control strategy, the robot can easily initiate its dynamic running behaviors with a flight phase and can move with similar body state profiles to those of the model, in all five testing speeds. The robot, embedded with the SLIP model but performing walking locomotion, further confirms the importance of finding an adequate template of the robot for dynamic locomotion. (paper)

  11. Low-Speed Control of Heavy-Load Transfer Robot with Long Telescopic Boom Based on Stribeck Friction Model

    Directory of Open Access Journals (Sweden)

    Bo You

    2012-01-01

    Full Text Available The severe low-speed creep phenomenon occurs in the telescopic boom system of a heavy-load transfer robot with a long telescopic boom as a result of nonlinear friction. In order to improve control precision and operation performance at low speeds, we built a three-loop control nonlinear model of an AC servo motor with Stribeck friction disturbance. Traditional proportional-integral-derivative controller (PID and fuzzy PID controls were, respectively, adopted in the position loop, and the control performance was simulated. The results showed that a system with fuzzy PID control eliminates “flat top” position tracking and “dead zone” speed tracking, which are generated by traditional PID, and thereby decreases the effect of friction on the performance of the servo system. This elimination also improved the tracking accuracy and robustness of the system.

  12. Construction of a Precursor Model for the Concept of Rolling Friction in the Thought of Preschool Age Children: A Socio-cognitive Teaching Intervention

    Science.gov (United States)

    Ravanis, Konstantinos; Koliopoulos, Dimitris; Boilevin, Jean-Marie

    2008-08-01

    The aim of this study was to explore the extent to which the characteristics of two teaching interventions can bring about cognitive progress in preschoolers with regard to the factors rolling friction depends on, when it is applied to an object that is freely rolling on a horizontal surface. The study was conducted in three phases: pre-test, teaching intervention, and post-test. Two teaching strategies were compared: one inspired by Piaget’s theory (Piagetian approach) and one inspired by post-Piagetian and Vygotkian assumptions (socio-cognitive approach). A statistically significant difference was found between the pre-test and post-test, providing evidence that the socio-cognitive approach allows for the creation of a more appropriate teaching framework compared to the Piagetian one.

  13. Texture analysis of a friction stir welded ultrafine grained Al–Al{sub 2}O{sub 3} composite produced by accumulative roll-bonding

    Energy Technology Data Exchange (ETDEWEB)

    Shamanian, Morteza, E-mail: shamanian@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Mohammadnezhad, Mahyar [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Szpunar, Jerzy [Department of Mechanical Engineering, University of Saskatchewan, Saskatoon, SK S7N5A9 (Canada)

    2014-12-05

    Highlights: • Aluminum matrix composite was successfully bonded using friction stir welding. • After welding process the fraction of low angle boundary area rapidly decreases. • The grain growth in the NZ is related the increase of temperature during the FSW. • The aluminum matrix composite has a strong Rotated Cube texture. • The weld nugget has a Rotated Cube and shear texture. - Abstract: In recent years, several studies have been focused on friction stir welding of aluminum alloys, and some researchers have also been reported on welding of aluminum-based composites. In the present research, ultrafine grained sheets of aluminum matrix composite (Al–Al{sub 2}O{sub 3}) were produced by accumulative roll-bonding (ARB) technique. The aluminum composite sheets were then joined by friction stir welding. The present work describes the effect of the FSW process on the microstructure and crystallographic textures in the base metal and weld nugget. Electron backscattered diffraction (EBSD) results demonstrated the existence of different grain orientations within the weld nugget as compared to the base metal. Al composite plates have a Rotated Cube texture component. Moreover, in the nugget, grain structure with Rotated Cube and shear texture developed. Friction stir welding coarsened the grain size in the weld zone from the original grain size of 3–17 μm.

  14. Texture analysis of a friction stir welded ultrafine grained Al–Al2O3 composite produced by accumulative roll-bonding

    International Nuclear Information System (INIS)

    Shamanian, Morteza; Mohammadnezhad, Mahyar; Szpunar, Jerzy

    2014-01-01

    Highlights: • Aluminum matrix composite was successfully bonded using friction stir welding. • After welding process the fraction of low angle boundary area rapidly decreases. • The grain growth in the NZ is related the increase of temperature during the FSW. • The aluminum matrix composite has a strong Rotated Cube texture. • The weld nugget has a Rotated Cube and shear texture. - Abstract: In recent years, several studies have been focused on friction stir welding of aluminum alloys, and some researchers have also been reported on welding of aluminum-based composites. In the present research, ultrafine grained sheets of aluminum matrix composite (Al–Al 2 O 3 ) were produced by accumulative roll-bonding (ARB) technique. The aluminum composite sheets were then joined by friction stir welding. The present work describes the effect of the FSW process on the microstructure and crystallographic textures in the base metal and weld nugget. Electron backscattered diffraction (EBSD) results demonstrated the existence of different grain orientations within the weld nugget as compared to the base metal. Al composite plates have a Rotated Cube texture component. Moreover, in the nugget, grain structure with Rotated Cube and shear texture developed. Friction stir welding coarsened the grain size in the weld zone from the original grain size of 3–17 μm

  15. Multi-source micro-friction identification for a class of cable-driven robots with passive backbone

    Science.gov (United States)

    Tjahjowidodo, Tegoeh; Zhu, Ke; Dailey, Wayne; Burdet, Etienne; Campolo, Domenico

    2016-12-01

    This paper analyses the dynamics of cable-driven robots with a passive backbone and develops techniques for their dynamic identification, which are tested on the H-Man, a planar cabled differential transmission robot for haptic interaction. The mechanism is optimized for human-robot interaction by accounting for the cost-benefit-ratio of the system, specifically by eliminating the necessity of an external force sensor to reduce the overall cost. As a consequence, this requires an effective dynamic model for accurate force feedback applications which include friction behavior in the system. We first consider the significance of friction in both the actuator and backbone spaces. Subsequently, we study the required complexity of the stiction model for the application. Different models representing different levels of complexity are investigated, ranging from the conventional approach of Coulomb to an advanced model which includes hysteresis. The results demonstrate each model's ability to capture the dynamic behavior of the system. In general, it is concluded that there is a trade-off between model accuracy and the model cost.

  16. Finger pad friction and tactile perception of laser treated, stamped and cold rolled micro-structured stainless steel sheet surfaces

    NARCIS (Netherlands)

    Zhang, Sheng; Zeng, X.; Matthews, D.T.A.; Igartua, A.; Rodriguez Vidal, E.; Contreras Fortes, J.; Van Der Heide, E.

    2017-01-01

    Tactile perception is a complex system, which depends on frictional interactions between skin and counter-body. The contact mechanics of tactile friction is governed by many factors such as the state and properties of skin and counter-body. In order to discover the connection between perception and

  17. Frictional performance of ball screw

    International Nuclear Information System (INIS)

    Nakashima, Katuhiro; Takafuji, Kazuki

    1985-01-01

    As feed screws, ball screws have become to be adopted in place of trapezoidal threads. The structure of ball screws is complex, but those are the indispensable component of NC machine tools and machining centers, and are frequently used for industrial robots. As the problems in the operation of ball screws, there are damage, life and the performance related to friction. As to the damage and life, though there is the problem of the load distribution on balls, the results of the research on rolling bearings are applied. The friction of ball screws consists of the friction of balls and a spiral groove, the friction of a ball and a ball, the friction in a ball-circulating mechanism and the viscous friction of lubricating oil. It was decided to synthetically examine the frictional performance of ball screws, such as driving torque, the variation of driving torque, efficiency, the formation of oil film and so on, under the working condition of wide range, using the screws with different accuracy and the nuts of various circuit number. The experimental setup and the processing of the experimental data, the driving performance of ball screws and so on are reported. (Kako, I.)

  18. Changes in texture and microstructure of friction stir welded Mg alloy during post-rolling and their effects on mechanical properties

    International Nuclear Information System (INIS)

    Xin, Renlong; Liu, Dejia; Xu, Zeren; Li, Bo; Liu, Qing

    2013-01-01

    A strong and complicated microtexture usually forms in stir zone (SZ) of friction stir welded (FSW) Mg alloys, which significantly influences the tensile properties of the joint due to the strong anisotropic mechanical properties of Mg alloys. This study aims to study the evolution of microstructure and texture in SZ during post-rolling of FSW AZ31 alloy and its effect on the tensile properties and fracture of the FSW joint. A detailed characterization of microstructure and texture in SZ and especially in SZ/base material (BM) interface was conducted on the FSW-undeformed and FSW-rolled specimens. Schmid factor (SF) changes for extension twinning and basal slip for transverse tensile tests were analyzed and discussed. It confirmed that the c-axis in SZ-center was parallel to welding direction (WD), but tilted towards transverse direction (TD) with the area moving to SZ-side. After subsequent rolling (by ∼2.5% strain), a large number of extension twins were found in SZ-side, but it was less in SZ-center. The production of extension twins rotated the grains in SZ-side and affected the transverse tensile properties significantly. The electron backscatter diffraction (EBSD) analyses showed that the SF of the twins was decreased compared with the matrix for both extension twinning and basal slip for the transverse tensile tests. So, the extension twins generated by post-rolling could cause texture strengthening for the transverse tensile tests. Moreover, the introduction of twin boundaries subdivided the grains, which also increased the tensile properties of the FSW-rolled specimens. The effect of post-rolling on the tensile properties and fracture was studied. It showed that post-rolling increased the transverse yield strength (YS) of the FSW AZ31 alloy, and the YS was increased further with the increase of rolling strain. The YS was raised from ∼87 MPa of the FSW-undeformed specimen to ∼115 MPa for the FSW-R-2.5 and ∼171 MPa for the FSW-R-7 specimens. Because

  19. Precision Hopping/Rolling Robotic Surface Probe Based on Tensegrity Structures

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to overcome the limitations of wheeled surface rovers by combining recent advances in ball-shaped soft-robots based on tensegrity structures (a tension...

  20. Friction Stir Welding of Al-B4C Composite Fabricated by Accumulative Roll Bonding: Evaluation of Microstructure and Mechanical Behavior

    Science.gov (United States)

    Moradi Faradonbeh, Alireza; Shamanian, Morteza; Edris, Hossein; Paidar, Moslem; Bozkurt, Yahya

    2018-02-01

    In this investigation, friction stir welding (FSW) of Al-B4C composite fabricated by 10 cycles accumulative roll bonding was conducted. In order to investigate the influences of pin geometry on microstructure and mechanical properties, four different pin geometries (cylindrical, square, triangular and hexagonal) were selected. It was found that FSW parameters had a major effect on the fragmentation and distribution of reinforcement particles in stir zone. When the tool travel speed was increased, the distribution of B4C particles was become gradually uniform in the aluminum matrix. The effect of tool rotational speed on the peak temperature was determined to be greater than the tool travel speed. The attained data of tensile properties and microhardness tests showed that the tool travel speed had bilateral effect on the tensile strength. The maximum tensile joint efficiency was obtained as 238% for FSWed of Al-2%B4C composite to annealed base Al sheet.

  1. Evaluation of Internal Friction versus Plastic Deformations Effects in Impact Dynamics Problems of Robotic Elements

    Directory of Open Access Journals (Sweden)

    Stelian Alaci

    2014-06-01

    Full Text Available The dynamical behavior study of robotic systems is obtained using multibody dynamics method. The joints met in robots are modeled in different manners. In a robotic joint the energy is lost via hysteretic work and plastic deformation work. The paper presents a comparative study for the results obtained by integration of the equations defining two limit models which describe the impact between two robot parts, modeled by the centric collision between two spheres with loss of energy. The motion equations characteristic for the two models are integrated and for a tangible situation, are presented comparatively, for different values of the coefficient of restitution, the time dependencies of impacting force between the two bodies as well as the hysteresis loops. Finally, an evaluation of the lost work during impact, for the whole range of coefficients of restitution, is completed, together with characteristic parameters of collision: approaching period, complete contact time, maximum approaching and plastic imprint.

  2. Enhanced Locomotion Efficiency of a Bio-inspired Walking Robot using Contact Surfaces with Frictional Anisotropy

    DEFF Research Database (Denmark)

    Manoonpong, Poramate; Petersen, Dennis; Kovalev, Alexander

    2016-01-01

    stability. It shows high frictional anisotropy due to an array of sloped denticles. The orientation of the denticles to the underlying collagenous material also strongly influences their mechanical interlocking with the substrate. This study not only opens up a new way of achieving energy-efficient legged...

  3. Kinematic effects of inertia and friction added by a robotic knee exoskeleton after prolonged walking.

    Science.gov (United States)

    Shirota, C; Tucker, M R; Lambercy, O; Gassert, R

    2017-07-01

    The capabilities of robotic gait assistive devices are ever increasing; however, their adoption outside of the lab is still limited. A critical barrier for the functionality of these devices are the still unknown mechanical properties of the human leg during dynamic conditions such as walking. We built a robotic knee exoskeleton to address this problem. Here, we present the effects of our device on the walking pattern of four subjects. We assessed the effects after a short period of acclimation as well as after a 1.5h walking protocol. We found that the knee exoskeleton decreased (towards extension) the peak hip extension and peak knee flexion of the leg with the exoskeleton, while minimally affecting the non-exoskeleton leg. Comparatively smaller changes occurred after prolonged walking. These results suggest that walking patterns attained after a few minutes of acclimation with a knee exoskeleton are stable for at least a couple of hours.

  4. Robotics

    Science.gov (United States)

    Popov, E. P.; Iurevich, E. I.

    The history and the current status of robotics are reviewed, as are the design, operation, and principal applications of industrial robots. Attention is given to programmable robots, robots with adaptive control and elements of artificial intelligence, and remotely controlled robots. The applications of robots discussed include mechanical engineering, cargo handling during transportation and storage, mining, and metallurgy. The future prospects of robotics are briefly outlined.

  5. Remote technology review: mobile robots continue to march (and crawl, roll, walk, slither, climb and swim) into action

    International Nuclear Information System (INIS)

    Meieran, H.

    1991-01-01

    Mobile robots are performing an increasing range of tasks in nuclear power plants and other nuclear facilities as well as in a wide spectrum of other hazardous industries and environments. The total number of such systems, many of which can be used in the nuclear industry, that have been, are being or will be built, now exceeds 350 separate units manufactured by more than 168 suppliers in 19 countries. In addition to being used in nuclear power plants themselves, they are being, or can be, employed in a variety of other nuclear applications, including hot cells, fuel reprocessing facilities, research establishments, waste sites, uranium mines, and decommissioning projects. The survey results reported here provide current statistics regarding terrestrial based mobile robots and remote teleoperator controlled vehicles (referred to collectively as mobile robots), underwater crawling and swimming robots (the latter known as remotely operated vehicles (ROVs)) and pipecrawlers. (author)

  6. Robotics

    International Nuclear Information System (INIS)

    Scheide, A.W.

    1983-01-01

    This article reviews some of the technical areas and history associated with robotics, provides information relative to the formation of a Robotics Industry Committee within the Industry Applications Society (IAS), and describes how all activities relating to robotics will be coordinated within the IEEE. Industrial robots are being used for material handling, processes such as coating and arc welding, and some mechanical and electronics assembly. An industrial robot is defined as a programmable, multifunctional manipulator designed to move material, parts, tools, or specialized devices through variable programmed motions for a variety of tasks. The initial focus of the Robotics Industry Committee will be on the application of robotics systems to the various industries that are represented within the IAS

  7. Robotics

    Energy Technology Data Exchange (ETDEWEB)

    Lorino, P; Altwegg, J M

    1985-05-01

    This article, which is aimed at the general reader, examines latest developments in, and the role of, modern robotics. The 7 main sections are sub-divided into 27 papers presented by 30 authors. The sections are as follows: 1) The role of robotics, 2) Robotics in the business world and what it can offer, 3) Study and development, 4) Utilisation, 5) Wages, 6) Conditions for success, and 7) Technological dynamics.

  8. Velocity Dependence in the Cyclic Friction Arising with Gears

    OpenAIRE

    García Armada, Elena; González de Santos, Pablo; Canudas de Wit, Carlos

    2002-01-01

    Recent research on friction in robot joints and transmission systems has considered meshing friction a position-dependent friction component. However, in this paper we show experimental evidence that meshing friction depends highly on joint speed.We identify the meshing friction in the gearboxes of a robotic leg, and we propose a new mathematical model that considers the rate dependency of meshing friction. The resulting model is validated through experimentation. Results...

  9. Investigation of squeal noise under positive friction characteristics condition provided by friction modifiers

    Science.gov (United States)

    Liu, Xiaogang; Meehan, Paul A.

    2016-06-01

    Field application of friction modifiers on the top of rail has been shown to effectively curb squeal and reduce lateral forces, but performance can be variable, according to other relevant research. Up to now, most investigations of friction modifiers were conducted in the field, where it is difficult to control or measure important parameters such as angle of attack, rolling speed, adhesion ratio etc. In the present investigation, the effect of different friction modifiers on the occurrence of squeal was investigated on a rolling contact two disk test rig. In particular, friction-creep curves and squeal sound pressure levels were measured under different rolling speeds and friction modifiers. The results show friction modifiers can eliminate or reduce the negative slope of friction-creep curves, but squeal noise still exists. Theoretical modelling of instantaneous creep behaviours reveals a possible reason why wheel squeal still exists after the application of friction modifiers.

  10. Robotics

    Indian Academy of Sciences (India)

    netic induction to detect an object. The development of ... end effector, inclination of object, magnetic and electric fields, etc. The sensors described ... In the case of a robot, the various actuators and motors have to be modelled. The major ...

  11. RELATIONSHIP BETWEEN ROLLING AND SLIP RESISTANCE IN ROLLING BEARINGS

    Directory of Open Access Journals (Sweden)

    L. M. Bondarenko

    2016-06-01

    Full Text Available Purpose. About one of the causes of slip rolling is known from the second half of the 19th century, it was believed that the slip resistance appears at the place of contact due to different speeds on the arc of contact. Only in the mid-20th century it was proved that this resistance is negligible in rolling resistance. However (for some unknown reason it is ignored the fact that in practice in rolling bearings may rotate both the inner ring with a stationary outer one, and vice versa almost in equal relations. It is not taken into account the fact that the ball or roller in the rolling bearings runs the different distance along the roller path of the outer and inner bearing cages in one revolution. This fact is not taken into account in determining the calculated values for the friction coefficient of a rolling bearing reduced to the shaft. Therefore, the aim of this work is to determine the influence of path length on the track riding the outer and inner race of the bearing on the determination of the calculated value of the coefficient of friction of rolling bearings is given to the shaft. Methodology. The solution technique is based on the theory of plane motion of a rigid body, the theory of Hertzian contact deformation and the analytical dependencies for determination of coefficient of rolling friction. Findings. The obtained dependences on determination of rolling resistance of the balls or rollers along the bearing tracks of inner and outer bearing cages as well as path difference metering of the rolling on them allows to analytically obtain the rolling resistance and slipping for any size of bearings and different devices of bearing units. It is also possible at the design stage of rolling nodes to handle not only the design but also the content of the node. Originality. Using the analytical dependences for determination of the rolling resistance of bodies at point and line contacts, and also account for the difference in the path of the

  12. Lubrication in cold rolling : Numerical simulation using multigrid techniques

    NARCIS (Netherlands)

    Lugt, Pieter Martin

    1992-01-01

    In the cold rolling process a lubricant is applied on the rolls and/or the strip mate­rial. Due to the velocities of the rolls and the strip, part of the lubricant is sheared into the contact causing, amongst others, a reduction of the friction. In this thesis a physical-mathematical model is

  13. Effects of rolling on characteristics of single-phase water flow in narrow rectangular ducts

    International Nuclear Information System (INIS)

    Xing Dianchuan; Yan Changqi; Sun Licheng; Xu Chao

    2012-01-01

    Highlights: ► Mass flow rate and friction pressure drop with different pressure head are compared. ► The effect of pressure head on flow fluctuation is considered theoretically. ► Time-mean and real-time friction pressure drop in different rolling motion are studied. ► Rolling motion influences the fluctuation of friction pressure drop in two aspects. ► New correlation for frictional coefficient in rolling motion is achieved. - Abstract: Experimental and theoretical studies of rolling effects on characteristics of single-phase water flow in narrow rectangular ducts are performed under ambient temperature and pressure. Two types of pressure head are supplied by elevate water tank and pump respectively. The results show that the frictional pressure drop under rolling condition fluctuates periodically, with its amplitude decaying as mean Reynolds number increase and the rolling amplitude decrease, while the amplitude is nearly invariable with rolling period. Rolling motion influences the fluctuation amplitude of frictional pressure drop in two aspects, on the one hand, rolling reduced periodical pulsing flow leads to the fluctuation of the frictional pressure drop, on the other hand, additional force acting on fluid near the wall due to the rolling motion makes local frictional resistance oscillate periodically. The mass flow rate oscillates periodically in rolling motion with the pressure head supplied by water tank, while its fluctuation is so weak that could be neglected for the case of the pressure head supplied by pump. An empirical correlation for the frictional coefficient under rolling condition is achieved, and the experimental data is well correlated. A mathematical model is also developed to study the effect of pressure head on mass flow rate fluctuation in rolling motion. The fluctuation amplitude of the mass flow rate decreases rapidly with a higher pressure head. Comparing with the vertical condition, rolling motion nearly has no effects on

  14. Effect of Rolling Resistance in Dem Models With Spherical Bodies

    Directory of Open Access Journals (Sweden)

    Dubina Radek

    2016-12-01

    Full Text Available The rolling resistance is an artificial moment arising on the contact of two discrete elements which mimics resistance of two grains of complex shape in contact rolling relatively to each other. The paper investigates the influence of rolling resistance on behaviour of an assembly of spherical discrete elements. Besides the resistance to rolling, the contacts between spherical particles obey the Hertzian law in normal straining and Coulomb model of friction in shear.

  15. An Omnidirectional Mobile Millimeters Size Micro-Robot with Novel Duel-Wheels

    Directory of Open Access Journals (Sweden)

    Zhenbo Li

    2006-09-01

    Full Text Available A millimeters size omni-directional mobile micro-robot is presented in this paper. A unique duel-wheel structure is designed for no-slip motion during the steering, by turning the slip friction between the wheel and ground into rolling friction. The robot was driven by four electromagnetic micromotors with 2.1mm×2.1mm×1.3mm size. Three of them are for translation and the other one is for rotation. Kinematics model is analyzed to prove the omni-directional mobility. Virtual-Winding Approach (VWA and PWM-Based Vector-Synthesize Approach(PBVSA current control methods are presented to satisfy a requirement of higher positioning accuracy. Experimental results demonstrate the feasibility of this concept.

  16. An Omnidirectional Mobile Millimeters Size Micro-Robot with Novel Duel-Wheels

    Directory of Open Access Journals (Sweden)

    Chen Zhang

    2008-11-01

    Full Text Available A millimeters size omni-directional mobile micro-robot is presented in this paper. A unique duel-wheel structure is designed for no-slip motion during the steering, by turning the slip friction between the wheel and ground into rolling friction. The robot was driven by four electromagnetic micromotors with 2.1mm?2.1mm?1.3mm size. Three of them are for translation and the other one is for rotation. Kinematics model is analyzed to prove the omni-directional mobility. Virtual-Winding Approach (VWA and PWM-Based VectorSynthesize Approach(PBVSA current control methods are presented to satisfy a requirement of higher positioning accuracy. Experimental results demonstrate the feasibility of this concept.

  17. Kalker's algorithm Fastsim solves tangential contact problems with slip-dependent friction and friction anisotropy

    Science.gov (United States)

    Piotrowski, J.

    2010-07-01

    This paper presents two extensions of Kalker's algorithm Fastsim of the simplified theory of rolling contact. The first extension is for solving tangential contact problems with the coefficient of friction depending on slip velocity. Two friction laws have been considered: with and without recuperation of the static friction. According to the tribological hypothesis for metallic bodies shear failure, the friction law without recuperation of static friction is more suitable for wheel and rail than the other one. Sample results present local quantities inside the contact area (division to slip and adhesion, traction) as well as global ones (creep forces as functions of creepages and rolling velocity). For the coefficient of friction diminishing with slip, the creep forces decay after reaching the maximum and they depend on the rolling velocity. The second extension is for solving tangential contact problems with friction anisotropy characterised by a convex set of the permissible tangential tractions. The effect of the anisotropy has been shown on examples of rolling without spin and in the presence of pure spin for the elliptical set. The friction anisotropy influences tangential tractions and creep forces. Sample results present local and global quantities. Both extensions have been described with the same language of formulation and they may be merged into one, joint algorithm.

  18. Kulturens rolle

    DEFF Research Database (Denmark)

    Hasse, Cathrine

    2007-01-01

    Kulturens rolle. Herunder kulturens betydning for psykologisk teori og forskning set i lyset af den stigende globalisering og væksten i kulturmøder. Der gives eksempler fra hverdagssituationer, den pædagogiske praksis, fra indvandrerforskning, turister men også fra avisernes referater af kulturmø......Kulturens rolle. Herunder kulturens betydning for psykologisk teori og forskning set i lyset af den stigende globalisering og væksten i kulturmøder. Der gives eksempler fra hverdagssituationer, den pædagogiske praksis, fra indvandrerforskning, turister men også fra avisernes referater af...

  19. Design of a Small Scale Roll to Roll Device

    OpenAIRE

    Pereira, Amon A; White, Edward; Kramer, Rebecca Krone

    2014-01-01

    In the soft robotics field, hyperelastic polymer films are used in conjunction with eutectic gallium indium to create flexible strain gages. However, rapid large scale manufacturing methods of such sensors have yet to be developed. Developing new manufacturing methods will allow for researchers to build and test new soft sensor concepts faster but also pave the way for future mass-production of these sensors for consumer or industrial consumption. One of those methods would be a Roll to...

  20. Friction coefficient dependence on electrostatic tribocharging

    Science.gov (United States)

    Burgo, Thiago A. L.; Silva, Cristiane A.; Balestrin, Lia B. S.; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers. PMID:23934227

  1. Friction coefficient dependence on electrostatic tribocharging.

    Science.gov (United States)

    Burgo, Thiago A L; Silva, Cristiane A; Balestrin, Lia B S; Galembeck, Fernando

    2013-01-01

    Friction between dielectric surfaces produces patterns of fixed, stable electric charges that in turn contribute electrostatic components to surface interactions between the contacting solids. The literature presents a wealth of information on the electronic contributions to friction in metals and semiconductors but the effect of triboelectricity on friction coefficients of dielectrics is as yet poorly defined and understood. In this work, friction coefficients were measured on tribocharged polytetrafluoroethylene (PTFE), using three different techniques. As a result, friction coefficients at the macro- and nanoscales increase many-fold when PTFE surfaces are tribocharged, but this effect is eliminated by silanization of glass spheres rolling on PTFE. In conclusion, tribocharging may supersede all other contributions to macro- and nanoscale friction coefficients in PTFE and probably in other insulating polymers.

  2. A Coupled Model for Work Roll Thermal Contour with Subsectional Cooling in Aluminum Strip Cold Rolling

    Directory of Open Access Journals (Sweden)

    Shao Jian

    2014-10-01

    Full Text Available Little attention had been given to the evaluation of subsectional cooling control ability under complicated working conditions. In this paper, heat generation was calculated by using finite difference method. Strip hardening, work roll elastic deformation and elastic recovery of strip were taken into account. The mean coefficient of convective heat transfer on work roll surface was simulated by FLUENT. Calculation model had used the alternative finite difference scheme, which improved the model stability and computing speed. The simulation result shows that subsectional cooling control ability is different between different rolling passes. Positive and negative control abilities are roughly the same in the same pass. The increase of rolled length, working pressure of header and friction coefficient has positive effect on subsectional cooling control ability, and the rolling speed is on the contrary. On the beginning of the pass, when work roll surface has not reached the stable temperature, control ability of subsectional cooling is mainly affected by rolled length. The effect of mean coefficient of convective heat transfer and coefficient of friction is linear. When rolling speed is over 500 m/min, control ability of subsectional cooling becomes stable.

  3. Dimensional ranges and rolling efficiency in a tandem cold rolling mill

    Energy Technology Data Exchange (ETDEWEB)

    Larkiola, J.

    1997-12-31

    In this work, physical models and a neural network theory have been combined in order to predict the properties of a steel strip and to optimise the process parameters in cold rolling. The prediction of the deformation resistance of the material and the friction parameter is based on the physical model presented by Bland, Ford and Ellis and artificial neural network computing (ANN). The accuracy of these models has been tested and proved by using a large amount of the measured data. With the aid of these models it has been shown that (a) the small change to the relative reduction distribution can have a clear effect upon the rolling efficiency, (b) the dimensional ranges of the tandem cold roll mill can be determined and optimised and (c) the possibility to cold roll a new product of new width, strength or thickness can be determined and the parameters of the tandem cold rolling process can be optimised. (orig.) 43 refs.

  4. Heat transfer modeling in asymmetrical sheet rolling of aluminium alloys with ultra high shear strain

    Directory of Open Access Journals (Sweden)

    Pesin Alexander

    2016-01-01

    Full Text Available Asymmetrical sheet rolling is a method of severe plastic deformation (SPD for production of aluminium alloys with UFG structure. Prediction of sheet temperature during SPD is important. The temperature of sheet is changed due to the conversion of mechanical work into heat through sliding on contact surfaces and high shear strain. Paper presents the results of FEM simulation of the effect of contact friction, rolling speed and rolls speed ratio on the heating of aluminium sheets during asymmetrical rolling.

  5. High speed friction microscopy and nanoscale friction coefficient mapping

    International Nuclear Information System (INIS)

    Bosse, James L; Lee, Sungjun; Huey, Bryan D; Andersen, Andreas Sø; Sutherland, Duncan S

    2014-01-01

    As mechanical devices in the nano/micro length scale are increasingly employed, it is crucial to understand nanoscale friction and wear especially at technically relevant sliding velocities. Accordingly, a novel technique has been developed for friction coefficient mapping (FCM), leveraging recent advances in high speed AFM. The technique efficiently acquires friction versus force curves based on a sequence of images at a single location, each with incrementally lower loads. As a result, true maps of the coefficient of friction can be uniquely calculated for heterogeneous surfaces. These parameters are determined at a scan velocity as fast as 2 mm s −1 for microfabricated SiO 2 mesas and Au coated pits, yielding results that are identical to traditional speed measurements despite being ∼1000 times faster. To demonstrate the upper limit of sliding velocity for the custom setup, the friction properties of mica are reported from 200 µm s −1 up to 2 cm s −1 . While FCM is applicable to any AFM and scanning speed, quantitative nanotribology investigations of heterogeneous sliding or rolling components are therefore uniquely possible, even at realistic velocities for devices such as MEMS, biological implants, or data storage systems. (paper)

  6. An advanced dissymmetric rolling model for online regulation

    Science.gov (United States)

    Cao, Trong-Son

    2017-10-01

    Roll-bite model is employed to predict the rolling force, torque as well as to estimate the forward slip for preset or online regulation at industrial rolling mills. The rolling process is often dissymmetric in terms of work-rolls rotation speeds and diameters as well as the friction conditions at upper and lower contact surfaces between work-rolls and the strip. The roll-bite model thus must be able to account for these dissymmetries and in the same time has to be accurate and fast enough for online applications. In the present study, a new method, namely Adapted Discretization Slab Method (ADSM) is proposed to obtain a robust roll-bite model, which can take into account the aforementioned dissymmetries and has a very short response time, lower than one millisecond. This model is based on the slab method, with an adaptive discretization and a global Newton-Raphson procedure to improve the convergence speed. The model was validated by comparing with other dissymmetric models proposed in the literature, as well as Finite Element simulations and industrial pilot trials. Furthermore, back-calculation tool was also constructed for friction management for both offline and online applications. With very short CPU time, the ADSM-based model is thus attractive for all online applications, both for cold and hot rolling.

  7. Rolled-up nanotechnology: 3D photonic materials by design

    International Nuclear Information System (INIS)

    Böttner, Stefan; Jorgensen, Matthew R.; Schmidt, Oliver G.

    2016-01-01

    Rolled-up nanotechnology involves the deposition of strained material layers for subsequent release and relaxation into functional structures with applications spanning several disciplines. Originally developed for use with semiconductor materials, over the last decade the processes involved in rolled-up nanotechnology have been applied across a wide palette of materials resulting in applications (among others) in micro robotics, energy storage, electronics, and photonics. Here we highlight the key advancements and future directions in rolled-up photonics, focusing on the diverse demonstrations of rolled-up three-dimensional microresonators which enable integrated sensing, micro-lasing, and out-of-plane routing of light.

  8. Contact conditions in skin-pass rolling

    DEFF Research Database (Denmark)

    Kijima, Hideo; Bay, Niels

    2007-01-01

    The special contact conditions in skin-pass rolling of steel strip is analysed by studying plane strain upsetting of thin sheet with low reduction applying long narrow tools and dry friction conditions. An extended sticking region is estimated by an elasto-plastic FEM analysis of the plane strain...... upsetting. This sticking region causes a highly inhomogeneous elasto-plastic deformation with large influence of work-hardening and friction. A numerical analysis of skin-pass rolling shows the same contact conditions, i.e. an extended sticking region around the center of the contact zone. The calculated...... size of the sticking region with varying contact length and pressure/reduction is experimentally verified by plane strain upsetting tests measuring the local surface deformation of the work pieces after unloading....

  9. Slipping and rolling on an inclined plane

    International Nuclear Information System (INIS)

    Aghamohammadi, Cina; Aghamohammadi, Amir

    2011-01-01

    In the first part of the paper, using a direct calculation two-dimensional motion of a particle sliding on an inclined plane is investigated for general values of friction coefficient (μ). A parametric equation for the trajectory of the particle is also obtained. In the second part of the paper, the motion of a sphere on the inclined plane is studied. It is shown that the evolution equation for the contact point of a sliding sphere is similar to that of a point particle sliding on an inclined plane whose friction coefficient is 7/2 μ. If μ > 2/7 tan θ, for any arbitrary initial velocity and angular velocity, the sphere will roll on the inclined plane after some finite time. In other cases, it will slip on the inclined plane. In the case of rolling, the centre of the sphere moves on a parabola. Finally the velocity and angular velocity of the sphere are exactly computed.

  10. Friction dampers, the positive side of friction

    NARCIS (Netherlands)

    Lopez Arteaga, I.; Nijmeijer, H.; Busturia, J.M.; Sas, P.; Munck, de M.

    2004-01-01

    Friction is frequently seen as an unwanted phenomenon whose influence has to be either minimised or controlled. In this work one of the positive sides of friction is investigated: friction damping. Friction dampers can be a cheap and efficient way to reduce the vibration levels of a wide range of

  11. Exploratorium: Robots.

    Science.gov (United States)

    Brand, Judith, Ed.

    2002-01-01

    This issue of Exploratorium Magazine focuses on the topic robotics. It explains how to make a vibrating robotic bug and features articles on robots. Contents include: (1) "Where Robot Mice and Robot Men Run Round in Robot Towns" (Ray Bradbury); (2) "Robots at Work" (Jake Widman); (3) "Make a Vibrating Robotic Bug" (Modesto Tamez); (4) "The Robot…

  12. Vacuum friction

    Science.gov (United States)

    Barnett, Stephen M.; Sonnleitner, Matthias

    2018-03-01

    We know that in empty space there is no preferred state of rest. This is true both in special relativity but also in Newtonian mechanics with its associated Galilean relativity. It comes as something of a surprise, therefore, to discover the existence a friction force associated with spontaneous emission. The resolution of this paradox relies on a central idea from special relativity even though our derivation of it is non-relativistic. We examine the possibility that the physics underlying this effect might be explored in an ion trap, via the observation of a superposition of different mass states.

  13. Transient effects in friction fractal asperity creep

    CERN Document Server

    Goedecke, Andreas

    2013-01-01

    Transient friction effects determine the behavior of a wide class of mechatronic systems. Classic examples are squealing brakes, stiction in robotic arms, or stick-slip in linear drives. To properly design and understand mechatronic systems of this type, good quantitative models of transient friction effects are of primary interest. The theory developed in this book approaches this problem bottom-up, by deriving the behavior of macroscopic friction surfaces from the microscopic surface physics. The model is based on two assumptions: First, rough surfaces are inherently fractal, exhibiting roughness on a wide range of scales. Second, transient friction effects are caused by creep enlargement of the real area of contact between two bodies. This work demonstrates the results of extensive Finite Element analyses of the creep behavior of surface asperities, and proposes a generalized multi-scale area iteration for calculating the time-dependent real contact between two bodies. The toolset is then demonstrated both...

  14. Spring-back of flexible roll forming bending process

    International Nuclear Information System (INIS)

    Zhang, Y; Kim, D H; Jung, D W

    2015-01-01

    Simulations are now widely used in the field of roll forming because of their convenience. Simulations provide a low cost, secure and fast analysis tool. Flexible roll forming provides the desired shapes with a one time forming process. For roll forming, the velocity of the sheet and friction are important factors to attain an ideal shape. Because it is a complicated process, simulations provide a better understanding of the roll forming process. Simulations were peformed using ABAQUS software linked to elastic-plastic modules which we developed taking into account of interactions between these fields [1]. The application of this method makes it possible to highlight the strain-stress and mechanical behaviour laws and the spring-back. Thus, the flexible roll forming and bending process can be well described by the simulation software and guide the actual machine. (paper)

  15. Cyberbotics Ltd. Webots™: Professional Mobile Robot Simulation

    Directory of Open Access Journals (Sweden)

    Olivier Michel

    2004-03-01

    Full Text Available Cyberbotics Ltd. develops Webots™, a mobile robotics simulation software that provides you with a rapid prototyping environment for modelling, programming and simulating mobile robots. The provided robot libraries enable you to transfer your control programs to several commercially available real mobile robots. Webots™ lets you define and modify a complete mobile robotics setup, even several different robots sharing the same environment. For each object, you can define a number of properties, such as shape, color, texture, mass, friction, etc. You can equip each robot with a large number of available sensors and actuators. You can program these robots using your favorite development environment, simulate them and optionally transfer the resulting programs onto your real robots. Webots™ has been developed in collaboration with the Swiss Federal Institute of Technology in Lausanne, thoroughly tested, well documented and continuously maintained for over 7 years. It is now the main commercial product available from Cyberbotics Ltd.

  16. WebotsTM: Professional Mobile Robot Simulation

    Directory of Open Access Journals (Sweden)

    Olivier Michel

    2008-11-01

    Full Text Available Cyberbotics Ltd. develops WebotsTM, a mobile robotics simulation software that provides you with a rapid prototyping environment for modelling, programming and simulating mobile robots. The provided robot libraries enable you to transfer your control programs to several commercially available real mobile robots. WebotsTM lets you define and modify a complete mobile robotics setup, even several different robots sharing the same environment. For each object, you can define a number of properties, such as shape, color, texture, mass, friction, etc. You can equip each robot with a large number of available sensors and actuators. You can program these robots using your favorite development environment, simulate them and optionally transfer the resulting programs onto your real robots. WebotsTM has been developed in collaboration with the Swiss Federal Institute of Technology in Lausanne, thoroughly tested, well documented and continuously maintained for over 7 years. It is now the main commercial product available from Cyberbotics Ltd.

  17. Static friction of porous bioceramic beta-TCP on intestinal mucus films.

    Science.gov (United States)

    Wang, Xin-Yu; Han, Ying-Chao; Jiang, Xin; Dai, Hong-Lian; Li, Shi-Pu

    2006-09-01

    The static friction behavior between a porous bioceramic material and an intestinal mucus film was investigated in order to develop a new intestine robotic endoscope. Here, the friction couple is porous beta-tricalcium phosphate (beta-TCP) and an artificial intestine mucus film. The effect of pore size of the beta-TCP material on the friction behavior is investigated. The results illustrated that in this friction system there is a relatively small normal force upon the intestinal mucus film of the intestine wall during locomotion. The maximum static friction force in this friction couple varies with the pore size of the porous beta-TCP material.

  18. Static friction of porous bioceramic β-TCP on intestinal mucus films

    International Nuclear Information System (INIS)

    Wang Xinyu; Han Yingchao; Jiang Xin; Dai Honglian; Li Shipu

    2006-01-01

    The static friction behavior between a porous bioceramic material and an intestinal mucus film was investigated in order to develop a new intestine robotic endoscope. Here, the friction couple is porous β-tricalcium phosphate (β-TCP) and an artificial intestine mucus film. The effect of pore size of the β-TCP material on the friction behavior is investigated. The results illustrated that in this friction system there is a relatively small normal force upon the intestinal mucus film of the intestine wall during locomotion. The maximum static friction force in this friction couple varies with the pore size of the porous β-TCP material

  19. Continuum Mechanical Modelling of Skin-pass Rolling

    DEFF Research Database (Denmark)

    Kijima, Hideo; Bay, Niels

    2007-01-01

    The special contact conditions in skin-pass rolling of steel strip is analyzed by studying plane strain upsetting of thin sheet with low reduction applying long narrow tools and dry friction conditions. An extended sticking region is estimated by an elasto-plastic FEM analysis of the plane strain...

  20. Precession of a Spinning Ball Rolling down an Inclined Plane

    Science.gov (United States)

    Cross, Rod

    2015-01-01

    A routine problem in an introductory physics course considers a rectangular block at rest on a plane inclined at angle a to the horizontal. In order for the block not to slide down the incline, the coefficient of sliding friction, µ, must be at least tan a. The situation is similar for the case of a ball rolling down an inclined plane. In order…

  1. Experimental and theoretical study on minimum achievable foil thickness during asymmetric rolling.

    Science.gov (United States)

    Tang, Delin; Liu, Xianghua; Song, Meng; Yu, Hailiang

    2014-01-01

    Parts produced by microforming are becoming ever smaller. Similarly, the foils required in micro-machines are becoming ever thinner. The asymmetric rolling technique is capable of producing foils that are thinner than those produced by the conventional rolling technique. The difference between asymmetric rolling and conventional rolling is the 'cross-shear' zone. However, the influence of the cross-shear zone on the minimum achievable foil thickness during asymmetric rolling is still uncertain. In this paper, we report experiments designed to understand this critical influencing factor on the minimum achievable thickness in asymmetric rolling. Results showed that the minimum achievable thickness of rolled foils produced by asymmetric rolling with a rolling speed ratio of 1.3 can be reduced to about 30% of that possible by conventional rolling technique. Furthermore, the minimum achievable thickness during asymmetric rolling could be correlated to the cross-shear ratio, which, in turn, could be related to the rolling speed ratio. From the experimental results, a formula to calculate the minimum achievable thickness was established, considering the parameters cross-shear ratio, friction coefficient, work roll radius, etc. in asymmetric rolling.

  2. Experimental and theoretical study on minimum achievable foil thickness during asymmetric rolling.

    Directory of Open Access Journals (Sweden)

    Delin Tang

    Full Text Available Parts produced by microforming are becoming ever smaller. Similarly, the foils required in micro-machines are becoming ever thinner. The asymmetric rolling technique is capable of producing foils that are thinner than those produced by the conventional rolling technique. The difference between asymmetric rolling and conventional rolling is the 'cross-shear' zone. However, the influence of the cross-shear zone on the minimum achievable foil thickness during asymmetric rolling is still uncertain. In this paper, we report experiments designed to understand this critical influencing factor on the minimum achievable thickness in asymmetric rolling. Results showed that the minimum achievable thickness of rolled foils produced by asymmetric rolling with a rolling speed ratio of 1.3 can be reduced to about 30% of that possible by conventional rolling technique. Furthermore, the minimum achievable thickness during asymmetric rolling could be correlated to the cross-shear ratio, which, in turn, could be related to the rolling speed ratio. From the experimental results, a formula to calculate the minimum achievable thickness was established, considering the parameters cross-shear ratio, friction coefficient, work roll radius, etc. in asymmetric rolling.

  3. Modeling and identification for robot motion control

    NARCIS (Netherlands)

    Kostic, D.; Jager, de A.G.; Steinbuch, M.; Kurfess, T.R.

    2004-01-01

    This chapter deals with the problems of robot modelling and identification for high-performance model-based motion control. A derivation of robot kinematic and dynamic models was explained. Modelling of friction effects was also discussed. Use of a writing task to establish correctness of the models

  4. Robot Actors, Robot Dramaturgies

    DEFF Research Database (Denmark)

    Jochum, Elizabeth

    This paper considers the use of tele-operated robots in live performance. Robots and performance have long been linked, from the working androids and automata staged in popular exhibitions during the nineteenth century and the robots featured at Cybernetic Serendipity (1968) and the World Expo...

  5. Pressure Drop Correlations of Single-Phase and Two-Phase Flow in Rolling Tubes

    International Nuclear Information System (INIS)

    Xia-xin Cao; Chang-qi Yan; Pu-zhen Gao; Zhong-ning Sun

    2006-01-01

    A series of experimental studies of frictional pressure drop for single phase and two-phase bubble flow in smooth rolling tubes were carried out. The tube inside diameters were 15 mm, 25 mm and 34.5 mm respectively, the rolling angles of tubes could be set as 10 deg. and 20 deg., and the rolling periods could be set as 5 s, 10 s and 15 s. Combining with the analysis of single-phase water motion, it was found that the traditional correlations for calculating single-phase frictional coefficient were not suitable for the rolling condition. Based on the experimental data, a new correlation for calculating single-phase frictional coefficient under rolling condition was presented, and the calculations not only agreed well with the experimental data, but also could display the periodically dynamic characteristics of frictional coefficients. Applying the new correlation to homogeneous flow model, two-phase frictional pressure drop of bubble flow in rolling tubes could be calculated, the results showed that the relative error between calculation and experimental data was less than ± 25%. (authors)

  6. Robotic architectures

    CSIR Research Space (South Africa)

    Mtshali, M

    2010-01-01

    Full Text Available In the development of mobile robotic systems, a robotic architecture plays a crucial role in interconnecting all the sub-systems and controlling the system. The design of robotic architectures for mobile autonomous robots is a challenging...

  7. Finite-element modeling of soft tissue rolling indentation.

    Science.gov (United States)

    Sangpradit, Kiattisak; Liu, Hongbin; Dasgupta, Prokar; Althoefer, Kaspar; Seneviratne, Lakmal D

    2011-12-01

    We describe a finite-element (FE) model for simulating wheel-rolling tissue deformations using a rolling FE model (RFEM). A wheeled probe performing rolling tissue indentation has proven to be a promising approach for compensating for the loss of haptic and tactile feedback experienced during robotic-assisted minimally invasive surgery (H. Liu, D. P. Noonan, B. J. Challacombe, P. Dasgupta, L. D. Seneviratne, and K. Althoefer, "Rolling mechanical imaging for tissue abnormality localization during minimally invasive surgery, " IEEE Trans. Biomed. Eng., vol. 57, no. 2, pp. 404-414, Feb. 2010; K. Sangpradit, H. Liu, L. Seneviratne, and K. Althoefer, "Tissue identification using inverse finite element analysis of rolling indentation," in Proc. IEEE Int. Conf. Robot. Autom. , Kobe, Japan, 2009, pp. 1250-1255; H. Liu, D. Noonan, K. Althoefer, and L. Seneviratne, "The rolling approach for soft tissue modeling and mechanical imaging during robot-assisted minimally invasive surgery," in Proc. IEEE Int. Conf. Robot. Autom., May 2008, pp. 845-850; H. Liu, P. Puangmali, D. Zbyszewski, O. Elhage, P. Dasgupta, J. S. Dai, L. Seneviratne, and K. Althoefer, "An indentation depth-force sensing wheeled probe for abnormality identification during minimally invasive surgery," Proc. Inst. Mech. Eng., H, vol. 224, no. 6, pp. 751-63, 2010; D. Noonan, H. Liu, Y. Zweiri, K. Althoefer, and L. Seneviratne, "A dual-function wheeled probe for tissue viscoelastic property identification during minimally invasive surgery," in Proc. IEEE Int. Conf. Robot. Autom. , 2008, pp. 2629-2634; H. Liu, J. Li, Q. I. Poon, L. D. Seneviratne, and K. Althoefer, "Miniaturized force indentation-depth sensor for tissue abnormality identification," IEEE Int. Conf. Robot. Autom., May 2010, pp. 3654-3659). A sound understanding of wheel-tissue rolling interaction dynamics will facilitate the evaluation of signals from rolling indentation. In this paper, we model the dynamic interactions between a wheeled probe and a

  8. Friction and wear properties of ZrO2/SiO2 composite nanoparticles

    International Nuclear Information System (INIS)

    Li Wei; Zheng Shaohua; Cao Bingqiang; Ma Shiyu

    2011-01-01

    In this article, the lubrication properties of ZrO 2 /SiO 2 composite nanoparticles modified with aluminum zirconium coupling agent as additives in lubricating oil under variable applied load and concentration fraction were reported. It was demonstrated that the modified nanoparticles as additives in lubrication can effectively improve the lubricating properties. Under an optimized concentration of 0.1 wt%, the average friction coefficient was reduced by 16.24%. This was because the nanoparticles go into the friction zone with the flow of lubricant, and then the sliding friction changed to rolling friction with a result of the reduction of the friction coefficient.

  9. Amplitude Dependent Internal Friction in a Mg-Al-Zn Alloy Studied after Thermal and Mechanical Treatment

    Directory of Open Access Journals (Sweden)

    Zuzanka Trojanová

    2017-10-01

    Full Text Available The amplitude-dependent internal friction of continuously-cast and rolled AZ31 magnesium alloy was measured in this study. Samples were annealed and quenched step by step; immediately after the treatment, the amplitude dependence of the logarithmic decrement was measured. Changes in the microstructure due to thermomechanical treatment were reflected in changes in the damping. Internal friction is influenced by the dislocation substructure and its modification due to solute atoms migration, microplastic deformation, and twins’ formation. Internal friction in the rolled sheets is affected by the rolling texture.

  10. On the nature of low temperature internal friction peaks in metallic glasses

    NARCIS (Netherlands)

    Khonik, VA; Spivak, LV

    Low temperature (30 friction in a metallic glass Ni60Nb40 subjected to preliminary inhomogeneous deformation by cold rolling, homogeneous tensile deformation or electrolytic charging with hydrogen is investigated. Cold rolling or hydrogenation result in appearance of similar

  11. Acoustics of friction

    Science.gov (United States)

    Akay, Adnan

    2002-04-01

    This article presents an overview of the acoustics of friction by covering friction sounds, friction-induced vibrations and waves in solids, and descriptions of other frictional phenomena related to acoustics. Friction, resulting from the sliding contact of solids, often gives rise to diverse forms of waves and oscillations within solids which frequently lead to radiation of sound to the surrounding media. Among the many everyday examples of friction sounds, violin music and brake noise in automobiles represent the two extremes in terms of the sounds they produce and the mechanisms by which they are generated. Of the multiple examples of friction sounds in nature, insect sounds are prominent. Friction also provides a means by which energy dissipation takes place at the interface of solids. Friction damping that develops between surfaces, such as joints and connections, in some cases requires only microscopic motion to dissipate energy. Modeling of friction-induced vibrations and friction damping in mechanical systems requires an accurate description of friction for which only approximations exist. While many of the components that contribute to friction can be modeled, computational requirements become prohibitive for their contemporaneous calculation. Furthermore, quantification of friction at the atomic scale still remains elusive. At the atomic scale, friction becomes a mechanism that converts the kinetic energy associated with the relative motion of surfaces to thermal energy. However, the description of the conversion to thermal energy represented by a disordered state of oscillations of atoms in a solid is still not well understood. At the macroscopic level, friction interacts with the vibrations and waves that it causes. Such interaction sets up a feedback between the friction force and waves at the surfaces, thereby making friction and surface motion interdependent. Such interdependence forms the basis for friction-induced motion as in the case of

  12. A fast nonlinear conjugate gradient based method for 3D concentrated frictional contact problems

    NARCIS (Netherlands)

    J. Zhao (Jing); E.A.H. Vollebregt (Edwin); C.W. Oosterlee (Cornelis)

    2015-01-01

    htmlabstractThis paper presents a fast numerical solver for a nonlinear constrained optimization problem, arising from 3D concentrated frictional shift and rolling contact problems with dry Coulomb friction. The solver combines an active set strategy with a nonlinear conjugate gradient method. One

  13. Rolling Shutter Motion Deblurring

    KAUST Repository

    Su, Shuochen

    2015-06-07

    Although motion blur and rolling shutter deformations are closely coupled artifacts in images taken with CMOS image sensors, the two phenomena have so far mostly been treated separately, with deblurring algorithms being unable to handle rolling shutter wobble, and rolling shutter algorithms being incapable of dealing with motion blur. We propose an approach that delivers sharp and undis torted output given a single rolling shutter motion blurred image. The key to achieving this is a global modeling of the camera motion trajectory, which enables each scanline of the image to be deblurred with the corresponding motion segment. We show the results of the proposed framework through experiments on synthetic and real data.

  14. Numerical analysis of viscous effect on ship rolling motions based on CFD

    Directory of Open Access Journals (Sweden)

    LUO Tian

    2017-03-01

    Full Text Available During the ship design procedure, the analysis of ship rolling motions is of great significance because the rolling motions have extraordinary effects on the sea-keeping, maneuverability and stability of a ship. It is difficult to simulate rolling motions due to the effect of viscosity, which causes many nonlinear components in computation. As such, the potential theory used for other ship motions cannot be used for rolling motions. This paper simulates the rolling motions of the DTMB 5512 ship model and the ship transverse section of the S60 ship model with a naoe-FOAM-SJTU solver using the Reynolds Averaged Navier Stokes(RANSmethod based on the OpenFOAM. The results of rolling motions are compared with the experimental data, which confirms the reliability of the meshes and results. For the ship transverse section of the S60 ship model, the damping coefficient is divided into three parts with the Euler and RANS methods:friction, vorticity and wave parts. For the DTMB 5512 ship model, the damping coefficient is also respectively analyzed, including the friction, vorticity, wave and bilge keel parts. The results in this paper show that the vorticity part accounts for the greatest proportion, while the friction part accounts for the least, and the bilge keels reduces the damping moment to a certain extent which shows the effect of rolling parameters on rolling motions and moments.

  15. Ship Roll Damping Control

    DEFF Research Database (Denmark)

    Perez, Tristan; Blanke, Mogens

    2012-01-01

    limitations and large variations of the spectral characteristics of wave-induced roll motion. This tutorial paper presents an account of the development of various ship roll motion control systems together with the challenges associated with their design. It discusses the assessment of performance...

  16. Cosmology with rolling tachyon

    Indian Academy of Sciences (India)

    Email: sami@iucaa.ernet.in. Abstract. We examine the possibility of rolling tachyon to play the dual role of inflaton at early epochs and dark matter at late times. We argue that enough inflation can be generated with the rolling tachyon either by invoking the large number of branes or brane world assisted inflation. However ...

  17. Robot engineering

    International Nuclear Information System (INIS)

    Jung, Seul

    2006-02-01

    This book deals with robot engineering, giving descriptions of robot's history, current tendency of robot field, work and characteristic of industrial robot, essential merit and vector, application of matrix, analysis of basic vector, expression of Denavit-Hartenberg, robot kinematics such as forward kinematics, inverse kinematics, cases of MATLAB program, and motion kinematics, robot kinetics like moment of inertia, centrifugal force and coriolis power, and Euler-Lagrangian equation course plan, SIMULINK position control of robots.

  18. Robot engineering

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Seul

    2006-02-15

    This book deals with robot engineering, giving descriptions of robot's history, current tendency of robot field, work and characteristic of industrial robot, essential merit and vector, application of matrix, analysis of basic vector, expression of Denavit-Hartenberg, robot kinematics such as forward kinematics, inverse kinematics, cases of MATLAB program, and motion kinematics, robot kinetics like moment of inertia, centrifugal force and coriolis power, and Euler-Lagrangian equation course plan, SIMULINK position control of robots.

  19. Friction enhancement in concertina locomotion of snakes

    Science.gov (United States)

    Marvi, Hamidreza; Hu, David L.

    2012-01-01

    Narrow crevices are challenging terrain for most organisms and biomimetic robots. Snakes move through crevices using sequential folding and unfolding of their bodies in the manner of an accordion or concertina. In this combined experimental and theoretical investigation, we elucidate this effective means of moving through channels. We measure the frictional properties of corn snakes, their body kinematics and the transverse forces they apply to channels of varying width and inclination. To climb channels inclined at 60°, we find snakes use a combination of ingenious friction-enhancing techniques, including digging their ventral scales to double their frictional coefficient and pushing channel walls transversely with up to nine times body weight. Theoretical modelling of a one-dimensional n-linked crawler is used to calculate the transverse force factor of safety: we find snakes push up to four times more than required to prevent sliding backwards, presumably trading metabolic energy for an assurance of wall stability. PMID:22728386

  20. Flow and heat transfer in laminar–turbulent transitional flow regime under rolling motion

    International Nuclear Information System (INIS)

    Yuan, Hongsheng; Tan, Sichao; Zhuang, Nailiang; Lan, Shu

    2016-01-01

    Highlights: • Flow and heat transfer experiment in transitional flow regime under rolling motion. • Increases of average friction factor and Nu were found. • Periodic breakdown of laminar flow contributes to the increase. • Nonlinear variation of pressure drop or Nu with Re also contributes to the increase. • Effect of critical Reynolds number shift was discussed. - Abstract: Flow and heat transfer characteristics under rolling motion are extremely important to thermohydraulic analysis of offshore nuclear reactors. An experimental study was conducted in a heated rectangular channel to investigate flow and heat transfer in laminar–turbulent transitional flow regime under rolling motion. The results showed that the average friction factor and Nusselt number are higher than that of the corresponding steady flow as the flow rate fluctuates in transitional flow regime. Larger relative flow rate fluctuation was observed under larger rolling amplitude or higher rolling frequency. In the same manner, larger increases of average friction factor and Nusselt number were achieved under larger rolling amplitude or higher rolling frequency. The increases were mainly caused by the flow rate fluctuation through periodic breakdown of laminar flow and development of turbulence in laminar–turbulent transitional flow regime. First, turbulence, which enhances the rate of momentum and energy exchange, occurs near the crest of flow rate wave even the flow is still in laminar flow regime according to the average Reynolds number. Second, as a result of rapid increases of the friction and heat transfer with Reynolds number in transitional flow regime, the increases of the friction and the heat transfer near the crest of flow rate wave are larger than the decreases of them near the trough of flow rate wave, which also contributes to increases of average friction and heat transfer. Additionally, the effect of critical Reynolds number shift under unsteady flow and heating

  1. On the nature of low temperature internal friction peaks in metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Khonik, V.A. [State Pedagogical Univ., Voronezh (Russian Federation); Spivak, L.V. [State Univ., Perm (Russian Federation)

    1996-01-01

    Low temperature (30 < T < 300 K) internal friction in a metallic glass Ni{sub 60}Nb{sub 40} subjected to preliminary inhomogeneous deformation by cold rolling, homogeneous tensile deformation or electrolytic charging with hydrogen is investigated. Cold rolling or hydrogenation result in appearance of similar internal friction peaks and hysteresis damping. Homogeneous deformation has no influence on low temperature internal friction. The phenomenon of microplastic deformation during hydrogenation of weakly stressed samples is revealed. It is argued that microplastic deformation of metallic glasses during hydrogenation without external stress takes place too. Plastic flow both on cold rolling and hydrogenation occurs via formation and motion of dislocation-like defects which are the reason of the observed anelastic anomalies. It is concluded that low temperature internal friction peaks described in the literature for as-cast, cold deformed and hydrogenated samples have common dislocation-like origin.

  2. Roll force prediction of high strength steel using foil rolling theory in cold skin pass rolling

    International Nuclear Information System (INIS)

    Song, Gil Ho; Jung, Jae Chook

    2013-01-01

    Skin pass rolling is a very important process for applying a certain elongation to a strip in the cold rolling and annealing processes, which play an important role in preventing the stretching of the yield point when the material is processed. The exact prediction of the rolling force is essential for obtaining a given elongation with the steel grade and strip size. Unlike hot rolling and cold rolling, skin pass rolling is used to apply an elongation of within 2% to the strip. Under a small reduction, it is difficult to predict the rolling force because the elastic deformation behavior of the rolls is complicated and a model for predicting the rolling force has not yet been established. Nevertheless, the exact prediction of the rolling force in skin pass rolling has gained increasing importance in recent times with the rapid development of high strength steels for use in automobiles. In this study, the possibility of predicting the rolling force in skin pass rolling for producing various steel grades was examined using foil rolling theory, which is known to have similar elastic deformation behavior of rolls in the roll bite. It was found that a noncircular arc model is more accurate than a circular model in predicting the roll force of high strength steel below TS 980 MPa in skin pass rolling

  3. Effect of friction on rolling tire-pavement interaction.

    Science.gov (United States)

    2010-11-01

    Accurate modeling of tirepavement contact behavior (i.e., distribution of contact tractions at the : interface) plays an important role in the analysis of pavement performance and vehicle driving safety. : The tirepavement contact is essentiall...

  4. Finite element method analysis of surface roughness transfer in micro flexible rolling

    Directory of Open Access Journals (Sweden)

    Qu Feijun

    2016-01-01

    Full Text Available Micro flexible rolling aims to fabricate submillimeter thick strips with varying thickness profile, where the surface quality of products is mainly determined by initial workpiece surface roughness and subsequent surface asperity flattening process, which is affected by process parameters during rolling. This paper shows a 3D finite element model for flexible rolling of a 250 μm thick workpiece with reduction of 20 to 50%, and rolling phase with thinner thickness indicates a better ability to decrease the surface roughness. Four types of initial workpiece surface roughness are studied in the simulation, and the influences of process parameters, such as friction coefficient, rolling speed and roll gap adjusting speed, on surface asperity flattening of workpieces with different initial surface roughness have been numerically investigated and analysed.

  5. A Spherical Aerial Terrestrial Robot

    Science.gov (United States)

    Dudley, Christopher J.

    This thesis focuses on the design of a novel, ultra-lightweight spherical aerial terrestrial robot (ATR). The ATR has the ability to fly through the air or roll on the ground, for applications that include search and rescue, mapping, surveillance, environmental sensing, and entertainment. The design centers around a micro-quadcopter encased in a lightweight spherical exoskeleton that can rotate about the quadcopter. The spherical exoskeleton offers agile ground locomotion while maintaining characteristics of a basic aerial robot in flying mode. A model of the system dynamics for both modes of locomotion is presented and utilized in simulations to generate potential trajectories for aerial and terrestrial locomotion. Details of the quadcopter and exoskeleton design and fabrication are discussed, including the robot's turning characteristic over ground and the spring-steel exoskeleton with carbon fiber axle. The capabilities of the ATR are experimentally tested and are in good agreement with model-simulated performance. An energy analysis is presented to validate the overall efficiency of the robot in both modes of locomotion. Experimentally-supported estimates show that the ATR can roll along the ground for over 12 minutes and cover the distance of 1.7 km, or it can fly for 4.82 minutes and travel 469 m, on a single 350 mAh battery. Compared to a traditional flying-only robot, the ATR traveling over the same distance in rolling mode is 2.63-times more efficient, and in flying mode the system is only 39 percent less efficient. Experimental results also demonstrate the ATR's transition from rolling to flying mode.

  6. Investigation of the rolling motion of a hollow cylinder using a smartphone

    Science.gov (United States)

    Puttharugsa, Chokchai; Khemmani, Supitch; Utayarat, Patipan; Luangtip, Wasutep

    2016-09-01

    This paper describes the use of smartphone’s gyroscope sensor to analyse a hollow cylinder rolling down an inclined plane. The smartphone (iPhone 4s) was attached to the end of hollow cylinder and was equipped with the Sensorlog application (Sensorlog app) to record the angular speed of rolling down an inclined plane. The experimental results agree with the theoretical model that is familiar to students for the rolling motion on an inclined plane. Moreover, the coefficients of static friction and kinetic friction were determined to be 0.205 ± 0.011 and 0.178 ± 0.003 from the measurements, respectively. This experiment demonstrated an alternative way to teach the rolling motion in a physics laboratory.

  7. Coefficient of friction of a starved lubricated spur gear pair

    International Nuclear Information System (INIS)

    Liu, Huaiju; Zhu, Caichao; Sun, Zhangdong; Zhang, Yuanyuan; Song, Chaosheng

    2016-01-01

    The frictional power loss issue of gear pairs becomes an important concern in both industry and academia due to the requirement of the energy saving and the improvement of power density of gear drives. A thermal starved elastohydrodynamic lubrication model is developed to study the tribological performance of a spur gear pair under starved lubrication conditions. The contact pressure, the film thickness, the temperature rise, the frictional power loss, as well as the coefficient of friction are evaluated by considering the variation of the curvature radius, the sliding/rolling motion, and the load distribution of gear tooth within the meshing period. Effects of lubrication starvation condition, load and speed on the coefficient of friction are studied.

  8. Friction torque in thrust ball bearings grease lubricated

    Science.gov (United States)

    Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

    2016-08-01

    The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

  9. NUMERICAL EVALUATION OF TEMPERATURE DISTRIBUTION IN THE ROLLING MILL ROLLS

    Directory of Open Access Journals (Sweden)

    José Claudino de Lira Júnior

    2013-06-01

    Full Text Available In hot rolling processes occur changes in the profile of the rolling mill rolls (expansion and contraction and constant wear due to mechanical stress and continuous thermal cycles of heating/cooling caused by contact rolled material- working roll and the cooling system by water jets in their surface, decreasing their lifetime. This paper presents a computational model to simulate the thermal performance of rolling mill rolls. The model was developed using the finite volume method for a transient two-dimensional system and allows calculating the temperature distribution of the rolling mill rolls under various conditions of service. Here it is investigated the influence of flow rate and temperature of the cooling water on the temperature distribution. The results show that the water temperature has greater influence than the water flow to control the surface temperature of the cylinders.

  10. Evolutionary robotics

    Indian Academy of Sciences (India)

    In evolutionary robotics, a suitable robot control system is developed automatically through evolution due to the interactions between the robot and its environment. It is a complicated task, as the robot and the environment constitute a highly dynamical system. Several methods have been tried by various investigators to ...

  11. Robot Aesthetics

    DEFF Research Database (Denmark)

    Jochum, Elizabeth Ann; Putnam, Lance Jonathan

    This paper considers art-based research practice in robotics through a discussion of our course and relevant research projects in autonomous art. The undergraduate course integrates basic concepts of computer science, robotic art, live performance and aesthetic theory. Through practice...... in robotics research (such as aesthetics, culture and perception), we believe robot aesthetics is an important area for research in contemporary aesthetics....

  12. Filigree Robotics

    DEFF Research Database (Denmark)

    Tamke, Martin; Evers, Henrik Leander; Clausen Nørgaard, Esben

    2016-01-01

    Filigree Robotics experiments with the combination of traditional ceramic craft with robotic fabrication in order to generate a new narrative of fine three-dimensional ceramic ornament for architecture.......Filigree Robotics experiments with the combination of traditional ceramic craft with robotic fabrication in order to generate a new narrative of fine three-dimensional ceramic ornament for architecture....

  13. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  14. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    2003-01-01

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory tracking...

  15. Hybrid Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bak, Thomas; Bendtsen, Jan Dimon; Ravn, Anders Peter

    2003-01-01

    We present a hybrid systems solution to the problem of trajectory tracking for a four-wheel steered four-wheel driven mobile robot. The robot is modelled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. Under normal driving conditions, a nonlinear trajectory trackin...

  16. A sphericon-shaped magnetic millirobot rolling on a surface actuated by an external wobbling magnetic field

    Directory of Open Access Journals (Sweden)

    Seungmun Jeon

    2017-05-01

    Full Text Available This paper proposes a novel sphericon-shaped magnetic millirobot (SSMM that can roll on a variety of surfaces. The SSMM comprises four identical half cones with a cylindrical magnet inserted into the geometric center. It can roll forward or backward on a surface with repeated rolling cone motions (wobbling motions. Since a rolling SSMM develops its entire surface by means of line contact, a relatively large maximum static friction force can make the SSMM move on a surface steadily and effectively. In this work, a new type of external wobbling magnetic field (EWMF was also derived to manipulate the SSMM’s rolling motions precisely. Then, the controlled rolling motions of prototype SSMMs under various surface conditions were demonstrated to examine the rolling ability of the proposed SSMM.

  17. Hydraulic bilateral construction robot; Yuatsushiki bilateral kensetsu robot

    Energy Technology Data Exchange (ETDEWEB)

    Maehata, K.; Mori, N. [Kayaba Industry Co. Ltd., Tokyo (Japan)

    1999-05-15

    Concerning a hydraulic bilateral construction robot, its system constitution, structures and functions of important components, and the results of some tests are explained, and the researches conducted at Gifu University are described. The construction robot in this report is a servo controlled system of a version developed from the mini-shovel now available in the market. It is equipped, in addition to an electrohydraulic servo control system, with various sensors for detecting the robot attitude, vibration, and load state, and with a camera for visualizing the surrounding landscape. It is also provided with a bilateral joy stick which is a remote control actuator capable of working sensation feedback and with a rocking unit that creates robot movements of rolling, pitching, and heaving. The construction robot discussed here, with output increased and response faster thanks to the employment of a hydraulic driving system for the aim of building a robot system superior in performance to the conventional model designed primarily for heavy duty, proves after tests to be a highly sophisticated remotely controlled robot control system. (NEDO)

  18. Sensor Fusion and Model Verification for a Mobile Robot

    DEFF Research Database (Denmark)

    Bisgaard, Morten; Vinther, Dennis; Østergaard, Kasper Zinck

    2005-01-01

    This paper presents the results of modeling, sensor fusion and model verification for a four-wheel driven, four-wheel steered mobile robot moving in outdoor terrain. The model derived for the robot describes the actuator and wheel dynamics and the vehicle kinematics, and includes friction terms...

  19. Proximity friction reexamined

    International Nuclear Information System (INIS)

    Krappe, H.J.

    1989-01-01

    The contribution of inelastic excitations to radial and tangential friction form-factors in heavy-ion collisions is investigated in the frame-work of perturbation theory. The dependence of the form factors on the essential geometrical and level-density parameters of the scattering system is exhibited in a rather closed form. The conditions for the existence of time-local friction coefficients are discussed. Results are compared to form factors from other models, in particular the transfer-related proximity friction. For the radial friction coefficient the inelastic excitation mechanism seems to be the dominant contribution in peripheral collisions. (orig.)

  20. Multi-fingered robotic hand

    Science.gov (United States)

    Ruoff, Carl F. (Inventor); Salisbury, Kenneth, Jr. (Inventor)

    1990-01-01

    A robotic hand is presented having a plurality of fingers, each having a plurality of joints pivotally connected one to the other. Actuators are connected at one end to an actuating and control mechanism mounted remotely from the hand and at the other end to the joints of the fingers for manipulating the fingers and passing externally of the robot manipulating arm in between the hand and the actuating and control mechanism. The fingers include pulleys to route the actuators within the fingers. Cable tension sensing structure mounted on a portion of the hand are disclosed, as is covering of the tip of each finger with a resilient and pliable friction enhancing surface.

  1. Rolling at small scales

    DEFF Research Database (Denmark)

    Nielsen, Kim L.; Niordson, Christian F.; Hutchinson, John W.

    2016-01-01

    The rolling process is widely used in the metal forming industry and has been so for many years. However, the process has attracted renewed interest as it recently has been adapted to very small scales where conventional plasticity theory cannot accurately predict the material response. It is well....... Metals are known to be stronger when large strain gradients appear over a few microns; hence, the forces involved in the rolling process are expected to increase relatively at these smaller scales. In the present numerical analysis, a steady-state modeling technique that enables convergence without...

  2. METHOD OF ROLLING URANIUM

    Science.gov (United States)

    Smith, C.S.

    1959-08-01

    A method is described for rolling uranium metal at relatively low temperatures and under non-oxidizing conditions. The method involves the steps of heating the uranium to 200 deg C in an oil bath, withdrawing the uranium and permitting the oil to drain so that only a thin protective coating remains and rolling the oil coated uranium at a temperature of 200 deg C to give about a 15% reduction in thickness at each pass. The operation may be repeated to accomplish about a 90% reduction without edge cracking, checking or any appreciable increase in brittleness.

  3. On the nature of low temperature internal friction peaks in metallic glasses

    International Nuclear Information System (INIS)

    Khonik, V.A.; Spivak, L.V.

    1996-01-01

    Low temperature (30 60 Nb 40 subjected to preliminary inhomogeneous deformation by cold rolling, homogeneous tensile deformation or electrolytic charging with hydrogen is investigated. Cold rolling or hydrogenation result in appearance of similar internal friction peaks and hysteresis damping. Homogeneous deformation has no influence on low temperature internal friction. The phenomenon of microplastic deformation during hydrogenation of weakly stressed samples is revealed. It is argued that microplastic deformation of metallic glasses during hydrogenation without external stress takes place too. Plastic flow both on cold rolling and hydrogenation occurs via formation and motion of dislocation-like defects which are the reason of the observed anelastic anomalies. It is concluded that low temperature internal friction peaks described in the literature for as-cast, cold deformed and hydrogenated samples have common dislocation-like origin

  4. Adaptive back-stepping control of the harmonic drive system with LuGre model-based friction compensation

    Science.gov (United States)

    Liu, Sen; Gang, Tieqiang

    2018-03-01

    Harmonic drives are widely used in aerospace and industrial robots. Flexibility, friction and parameter uncertainty will result in transmission performance degradation. In this paper, an adaptive back-stepping method with friction compensation is proposed to improve the tracking performance of the harmonic drive system. The nonlinear friction is described by LuGre model and compensated with a friction observer, and the uncertainty of model parameters is resolved by adaptive parameter estimation method. By using Lyapunov stability theory, it is proved that all the errors of the closed-loop system are uniformly ultimately bounded. Simulations illustrate the effectiveness of our friction compensation method.

  5. Person og Rolle

    DEFF Research Database (Denmark)

    Szatkowski, Janek

    2011-01-01

    Distinktionen mellem person og rolle forslås som grundlag for et præcist og anlytisk anvendeligt begreb om performativitet. Begrebet tager sigte på at beskrive enkeltindividers og gruppers kommunikation med henblik på hvordan kommunikation etableres. Performativitet gør det muligt at iagttage den...

  6. Ship Roll Motion Control

    DEFF Research Database (Denmark)

    Perez, Tristan; Blanke, Mogens

    2010-01-01

    . This tutorial paper presents an account of the development of various ship roll motion control systems and the challenges associated with their design. The paper discusses how to assess performance, the applicability of dierent models, and control methods that have been applied in the past....

  7. Rolling Cylinder Phase 1

    DEFF Research Database (Denmark)

    Margheritini, Lucia; Taraborrelli, Valeria Taraborrelli

    Margheritini and Valeria Taraborrelli(valeria.taraborrelli@hotmail.it) with a total of 3 day visit from the developers. Laboratory tests in irregular waves will be performed by Lucia Margheritini. The report is aimed at the first stage testing of the Rolling Cylinder wave energy device. This phase includes...

  8. Software and Hardware control of a hybrid robot for switching between leg-type and wheel-type modes

    OpenAIRE

    Botelho, Wagner Tanaka; Okada, Tokuji; Mahmoud, Abeer; Shimizu, Toshimi

    2011-01-01

    One of the objectives of the paper is to describe the hybrid robot PEOPLER-II (Perpendicularly Oriented Planetary Legged Robot) with regard to switching between leg-type and wheel-type. Our robot has an easier design and control system than other hybrid robots. The software and hardware control in the process of performing five robot tasks are considered. These are the walking, rolling, switching, turning and spinning. In the switching task, we show the control method based on minimization of...

  9. Robotic vehicle with multiple tracked mobility platforms

    Science.gov (United States)

    Salton, Jonathan R [Albuquerque, NM; Buttz, James H [Albuquerque, NM; Garretson, Justin [Albuquerque, NM; Hayward, David R [Wetmore, CO; Hobart, Clinton G [Albuquerque, NM; Deuel, Jr., Jamieson K.

    2012-07-24

    A robotic vehicle having two or more tracked mobility platforms that are mechanically linked together with a two-dimensional coupling, thereby forming a composite vehicle of increased mobility. The robotic vehicle is operative in hazardous environments and can be capable of semi-submersible operation. The robotic vehicle is capable of remote controlled operation via radio frequency and/or fiber optic communication link to a remote operator control unit. The tracks have a plurality of track-edge scallop cut-outs that allow the tracks to easily grab onto and roll across railroad tracks, especially when crossing the railroad tracks at an oblique angle.

  10. Experimental determination of heat transfer coefficients in roll bite and air cooling for computer simulations of 1100 MPa carbon steel rolling

    Science.gov (United States)

    Leinonen, Olli; Ilmola, Joonas; Seppälä, Oskari; Pohjonen, Aarne; Paavola, Jussi; Koskenniska, Sami; Larkiola, Jari

    2018-05-01

    In modeling of hot rolling pass schedules the heat transfer phenomena have to be known. Radiation to ambient, between rolls and a steel slab as well as heat transfer in contacts must be considered to achieve accurate temperature distribution and thereby accurate material behavior in simulations. Additional heat is generated by friction between the slab and the work roll and by plastic deformation. These phenomena must be taken into account when the effective heat transfer coefficient is determined from experimental data. In this paper we determine the effective heat transfer coefficient at the contact interface and emissivity factor of slab surface for 1100MPa strength carbon steel for hot rolling simulations. Experimental pilot rolling test were carried out and slab temperatures gathered right below the interface and at the mid thickness of the slab. Emissivity factor tests were carried out in the same manner but without rolling. Experimental data is utilized to derive contact heat transfer coefficient at the interface and emissivity factor of slab surface. Pilot rolling test is reproduced in FE-analysis to further refine the heat transfer coefficient and emissivity factor. Material mechanical properties at rolling temperatures were determined by Gleeble™ thermo-mechanical simulator and IDS thermodynamic-kinetic-empirical software.

  11. Numerical Study of Tire Hydroplaning Based on Power Spectrum of Asphalt Pavement and Kinetic Friction Coefficient

    OpenAIRE

    Shengze Zhu; Xiuyu Liu; Qingqing Cao; Xiaoming Huang

    2017-01-01

    Hydroplaning is a driving phenomenon threating vehicle’s control stability and safety. It happens when tire rolls on wet pavement with high speed that hydrodynamic force uplifts the tire. Accurate numerical simulation to reveal the mechanism of hydroplaning and evaluate the function of relevant factors in this process is significant. In order to describe the friction behaviors of tire-pavement interaction, kinetic friction coefficient curve of tire rubber and asphalt pavement was obtained by ...

  12. Robotic environments

    NARCIS (Netherlands)

    Bier, H.H.

    2011-01-01

    Technological and conceptual advances in fields such as artificial intelligence, robotics, and material science have enabled robotic architectural environments to be implemented and tested in the last decade in virtual and physical prototypes. These prototypes are incorporating sensing-actuating

  13. Process Development And Simulation For Cold Fabrication Of Doubly Curved Metal Plate By Using Line Array Roll Set

    International Nuclear Information System (INIS)

    Shim, D. S.; Jung, C. G.; Seong, D. Y.; Yang, D. Y.; Han, J. M.; Han, M. S.

    2007-01-01

    For effective manufacturing of a doubly curved sheet metal, a novel sheet metal forming process is proposed. The suggested process uses a Line Array Roll Set (LARS) composed of a pair of upper and lower roll assemblies in a symmetric manner. The process offers flexibility as compared with the conventional manufacturing processes, because it does not require any complex-shaped die and loss of material by blank-holding is minimized. LARS allows flexibility of the incremental forming process and adopts the principle of bending deformation, resulting in a slight deformation in thickness. Rolls composed of line array roll sets are divided into a driving roll row and two idle roll rows. The arrayed rolls in the central lines of the upper and lower roll assemblies are motor-driven so that they deform and transfer the sheet metal using friction between the rolls and the sheet metal. The remaining rolls are idle rolls, generating bending deformation with driving rolls. Furthermore, all the rolls are movable in any direction so that they are adaptable to any size or shape of the desired three-dimensional configuration. In the process, the sheet is deformed incrementally as deformation proceeds simultaneously in rolling and transverse directions step by step. Consequently, it can be applied to the fabrication of doubly curved ship hull plates by undergoing several passes. In this work, FEM simulations are carried out for verification of the proposed incremental forming system using the chosen design parameters. Based on the results of the simulation, the relationship between the roll set configuration and the curvature of a sheet metal is determined. The process information such as the forming loads and torques acting on every roll is analyzed as important data for the design and development of the manufacturing system

  14. Healthcare Robotics

    OpenAIRE

    Riek, Laurel D.

    2017-01-01

    Robots have the potential to be a game changer in healthcare: improving health and well-being, filling care gaps, supporting care givers, and aiding health care workers. However, before robots are able to be widely deployed, it is crucial that both the research and industrial communities work together to establish a strong evidence-base for healthcare robotics, and surmount likely adoption barriers. This article presents a broad contextualization of robots in healthcare by identifying key sta...

  15. Industrial Robots.

    Science.gov (United States)

    Reed, Dean; Harden, Thomas K.

    Robots are mechanical devices that can be programmed to perform some task of manipulation or locomotion under automatic control. This paper discusses: (1) early developments of the robotics industry in the United States; (2) the present structure of the industry; (3) noneconomic factors related to the use of robots; (4) labor considerations…

  16. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  17. State Estimation for Tensegrity Robots

    Science.gov (United States)

    Caluwaerts, Ken; Bruce, Jonathan; Friesen, Jeffrey M.; Sunspiral, Vytas

    2016-01-01

    Tensegrity robots are a class of compliant robots that have many desirable traits when designing mass efficient systems that must interact with uncertain environments. Various promising control approaches have been proposed for tensegrity systems in simulation. Unfortunately, state estimation methods for tensegrity robots have not yet been thoroughly studied. In this paper, we present the design and evaluation of a state estimator for tensegrity robots. This state estimator will enable existing and future control algorithms to transfer from simulation to hardware. Our approach is based on the unscented Kalman filter (UKF) and combines inertial measurements, ultra wideband time-of-flight ranging measurements, and actuator state information. We evaluate the effectiveness of our method on the SUPERball, a tensegrity based planetary exploration robotic prototype. In particular, we conduct tests for evaluating both the robot's success in estimating global position in relation to fixed ranging base stations during rolling maneuvers as well as local behavior due to small-amplitude deformations induced by cable actuation.

  18. Rolling bearing analysis

    CERN Document Server

    Harris, Tedric A

    2001-01-01

    One of the most well-known experts in the field brings cutting-edge research to practitioners in the new edition of this important reference. Covers the improved mathematical calculations for rolling bearing endurance developed by the American Society of Mechanical Engineers and the Society of Lubrication and Tribology Engineers. Updated with new material on Condition-Based Maintenance, new testing methods, and new bearing materials.

  19. Roll of honour

    Energy Technology Data Exchange (ETDEWEB)

    Moxon, Suzanne

    1999-07-01

    This article gives details of the design and construction of dams selected by members of the dam construction industry for praise as feats of construction. The dams covered in the roll of honour include the dam at the Guri hydroelectric power station in Venezuela on the Caroni river, the Contra dam on the Verzrasca river in Switzerland, and the double curvature arc Ertan dam on the Yalong river in China. (UK)

  20. Shear Roll Mill Reactivation

    Science.gov (United States)

    2012-09-13

    pneumatically operated paste dumper and belt conveyor system, the loss in weight feeder system, the hydraulically operated shear roll mill, the pellet...out feed belt conveyor , and the pack out system comprised of the metal detector, scale, and pack out empty and full drum roller conveyors . Page | 4...feed hopper and conveyor supplying the loss in weight feeder were turned on, and it was verified that these items functioned as designed . The

  1. Friction law and hysteresis in granular materials

    Science.gov (United States)

    DeGiuli, E.; Wyart, M.

    2017-08-01

    The macroscopic friction of particulate materials often weakens as the flow rate is increased, leading to potentially disastrous intermittent phenomena including earthquakes and landslides. We theoretically and numerically study this phenomenon in simple granular materials. We show that velocity weakening, corresponding to a nonmonotonic behavior in the friction law, μ(I), is present even if the dynamic and static microscopic friction coefficients are identical, but disappears for softer particles. We argue that this instability is induced by endogenous acoustic noise, which tends to make contacts slide, leading to faster flow and increased noise. We show that soft spots, or excitable regions in the materials, correspond to rolling contacts that are about to slide, whose density is described by a nontrivial exponent θs. We build a microscopic theory for the nonmonotonicity of μ(I), which also predicts the scaling behavior of acoustic noise, the fraction of sliding contacts χ, and the sliding velocity, in terms of θs. Surprisingly, these quantities have no limit when particles become infinitely hard, as confirmed numerically. Our analysis rationalizes previously unexplained observations and makes experimentally testable predictions.

  2. Friction law and hysteresis in granular materials.

    Science.gov (United States)

    DeGiuli, E; Wyart, M

    2017-08-29

    The macroscopic friction of particulate materials often weakens as the flow rate is increased, leading to potentially disastrous intermittent phenomena including earthquakes and landslides. We theoretically and numerically study this phenomenon in simple granular materials. We show that velocity weakening, corresponding to a nonmonotonic behavior in the friction law, [Formula: see text], is present even if the dynamic and static microscopic friction coefficients are identical, but disappears for softer particles. We argue that this instability is induced by endogenous acoustic noise, which tends to make contacts slide, leading to faster flow and increased noise. We show that soft spots, or excitable regions in the materials, correspond to rolling contacts that are about to slide, whose density is described by a nontrivial exponent [Formula: see text] We build a microscopic theory for the nonmonotonicity of [Formula: see text], which also predicts the scaling behavior of acoustic noise, the fraction of sliding contacts [Formula: see text], and the sliding velocity, in terms of [Formula: see text] Surprisingly, these quantities have no limit when particles become infinitely hard, as confirmed numerically. Our analysis rationalizes previously unexplained observations and makes experimentally testable predictions.

  3. Science 101: What Causes Friction?

    Science.gov (United States)

    Robertson, Bill

    2014-01-01

    Defining friction and asking what causes it might seem like a trivial question. Friction seems simple enough to understand. Friction is a force between surfaces that pushes against things that are moving or tending to move, and the rougher the surfaces, the greater the friction. Bill Robertson answers this by saying, "Well, not exactly".…

  4. Robot Mechanisms

    CERN Document Server

    Lenarcic, Jadran; Stanišić, Michael M

    2013-01-01

    This book provides a comprehensive introduction to the area of robot mechanisms, primarily considering industrial manipulators and humanoid arms. The book is intended for both teaching and self-study. Emphasis is given to the fundamentals of kinematic analysis and the design of robot mechanisms. The coverage of topics is untypical. The focus is on robot kinematics. The book creates a balance between theoretical and practical aspects in the development and application of robot mechanisms, and includes the latest achievements and trends in robot science and technology.

  5. Paediatric treadmill friction injuries.

    Science.gov (United States)

    Jeremijenko, Luke; Mott, Jonathan; Wallis, Belinda; Kimble, Roy

    2009-05-01

    The aim of this study was to report on the severity and incidence of children injured by treadmills and to promote the implementation of safety standards. This retrospective review of children with treadmill friction injuries was conducted in a single tertiary-level burns centre in Australia between January 1997 and June 2007. The study revealed 37 children who sustained paediatric treadmill friction injuries. This was a presentation of 1% of all burns. Thirty-three (90%) of the injuries occurred in the last 3.5 years (January 2004 to June 2007). The modal age was 3.2 years. Thirty-three (90%) injuries were either full thickness or deep partial friction burns. Eleven (30%) required split thickness skin grafts. Of those who became entrapped, 100% required skin grafting. This study found that paediatric treadmill friction injuries are severe and increasing in incidence. Australian standards should be developed, implemented and mandated to reduce this preventable and severe injury.

  6. Friction stir welding tool

    Science.gov (United States)

    Tolle,; Charles R. , Clark; Denis E. , Barnes; Timothy, A [Ammon, ID

    2008-04-15

    A friction stir welding tool is described and which includes a shank portion; a shoulder portion which is releasably engageable with the shank portion; and a pin which is releasably engageable with the shoulder portion.

  7. Robot Futures

    DEFF Research Database (Denmark)

    Christoffersen, Anja; Grindsted Nielsen, Sally; Jochum, Elizabeth Ann

    Robots are increasingly used in health care settings, e.g., as homecare assistants and personal companions. One challenge for personal robots in the home is acceptance. We describe an innovative approach to influencing the acceptance of care robots using theatrical performance. Live performance...... is a useful testbed for developing and evaluating what makes robots expressive; it is also a useful platform for designing robot behaviors and dialogue that result in believable characters. Therefore theatre is a valuable testbed for studying human-robot interaction (HRI). We investigate how audiences...... perceive social robots interacting with humans in a future care scenario through a scripted performance. We discuss our methods and initial findings, and outline future work....

  8. Robotics education

    International Nuclear Information System (INIS)

    Benton, O.

    1984-01-01

    Robotics education courses are rapidly spreading throughout the nation's colleges and universities. Engineering schools are offering robotics courses as part of their mechanical or manufacturing engineering degree program. Two year colleges are developing an Associate Degree in robotics. In addition to regular courses, colleges are offering seminars in robotics and related fields. These seminars draw excellent participation at costs running up to $200 per day for each participant. The last one drew 275 people from Texas to Virginia. Seminars are also offered by trade associations, private consulting firms, and robot vendors. IBM, for example, has the Robotic Assembly Institute in Boca Raton and charges about $1,000 per week for course. This is basically for owners of IBM robots. Education (and training) can be as short as one day or as long as two years. Here is the educational pattern that is developing now

  9. Roll-to-Roll production of carbon nanotubes based supercapacitors

    Science.gov (United States)

    Zhu, Jingyi; Childress, Anthony; Karakaya, Mehmet; Roberts, Mark; Arcilla-Velez, Margarita; Podila, Ramakrishna; Rao, Apparao

    2014-03-01

    Carbon nanomaterials provide an excellent platform for electrochemical double layer capacitors (EDLCs). However, current industrial methods for producing carbon nanotubes are expensive and thereby increase the costs of energy storage to more than 10 Wh/kg. In this regard, we developed a facile roll-to-roll production technology for scalable manufacturing of multi-walled carbon nanotubes (MWNTs) with variable density on run-of-the-mill kitchen Al foils. Our method produces MWNTs with diameter (heights) between 50-100 nm (10-100 μm), and a specific capacitance as high as ~ 100 F/g in non-aqueous electrolytes. In this talk, the fundamental challenges involved in EDLC-suitable MWNT growth, roll-to-roll production, and device manufacturing will be discussed along with electrochemical characteristics of roll-to-roll MWNTs. Research supported by NSF CMMI Grant1246800.

  10. Spray rolling aluminum alloy strip

    Energy Technology Data Exchange (ETDEWEB)

    McHugh, Kevin M.; Delplanque, J.-P.; Johnson, S.B.; Lavernia, E.J.; Zhou, Y.; Lin, Y

    2004-10-10

    Spray rolling combines spray forming with twin-roll casting to process metal flat products. It consists of atomizing molten metal with a high velocity inert gas, cooling the resultant droplets in flight and directing the spray between mill rolls. In-flight convection heat transfer from atomized droplets teams with conductive cooling at the rolls to rapidly remove the alloy's latent heat. Hot deformation of the semi-solid material in the rolls results in fully consolidated, rapidly solidified product. While similar in some ways to twin-roll casting, spray rolling has the advantage of being able to process alloys with broad freezing ranges at high production rates. This paper describes the process and summarizes microstructure and tensile properties of spray-rolled 2124 and 7050 aluminum alloy strips. A Lagrangian/Eulerian poly-dispersed spray flight and deposition model is described that provides some insight into the development of the spray rolling process. This spray model follows droplets during flight toward the rolls, through impact and spreading, and includes oxide film formation and breakup when relevant.

  11. Structure and Mechanical Properties of Friction Stir Weld Joints of Magnesium Alloy AZ31

    Science.gov (United States)

    Nagasawa, T.; Otsuka, M.; Yokota, T.; Ueki, T.

    The applicability of friction stir welding to hot rolled sheet of commercial magnesium alloy AZ31 plates has been investigated. Friction stir weld joint showed mechanical strength comparable to that of base material, though the ductility remained at one half of that of the latter. The results are consistent with the microstructure which is characterized by a fine grained bond layer bounded by-intermediate grained base metals. It is found that both anodizing treatment and insertion of aluminum foil between batting faces do not degrade the joint properties at all. The results suggest that friction stir welding can be potentially applied to magnesium alloy.

  12. Reflections on Friction in Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Yair Rezek

    2010-08-01

    Full Text Available Distinctly quantum friction effects of three types are surveyed: internalfriction, measurement-induced friction, and quantum-fluctuation-induced friction. We demonstrate that external driving will lead to quantum internal friction, and critique the measurement-based interpretation of friction. We conclude that in general systems will experience internal and external quantum friction over and beyond the classical frictional contributions.

  13. Minimizing Hexapod Robot Foot Deviations Using Multilayer Perceptron

    Directory of Open Access Journals (Sweden)

    Vytautas Valaitis

    2015-12-01

    Full Text Available Rough-terrain traversability is one of the most valuable characteristics of walking robots. Even despite their slower speeds and more complex control algorithms, walking robots have far wider usability than wheeled or tracked robots. However, efficient movement over irregular surfaces can only be achieved by eliminating all possible difficulties, which in many cases are caused by a high number of degrees of freedom, feet slippage, frictions and inertias between different robot parts or even badly developed inverse kinematics (IK. In this paper we address the hexapod robot-foot deviation problem. We compare the foot-positioning accuracy of unconfigured inverse kinematics and Multilayer Perceptron-based (MLP methods via theory, computer modelling and experiments on a physical robot. Using MLP-based methods, we were able to significantly decrease deviations while reaching desired positions with the hexapod's foot. Furthermore, this method is able to compensate for deviations of the robot arising from any possible reason.

  14. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  15. The influence of suspension components friction on race car vertical dynamics

    Science.gov (United States)

    Benini, Claudio; Gadola, Marco; Chindamo, Daniel; Uberti, Stefano; Marchesin, Felipe P.; Barbosa, Roberto S.

    2017-03-01

    This work analyses the effect of friction in suspension components on a race car vertical dynamics. It is a matter of fact that race cars aim at maximising their performance, focusing the attention mostly on aerodynamics and suspension tuning: suspension vertical and rolling stiffness and damping are parameters to be taken into account for an optimal setup. Furthermore, friction in suspension components must not be ignored. After a test session carried out with a F4 on a Four Poster rig, friction was detected on the front suspension. The real data gathered allow the validation of an analytical model with friction, confirming that its influence is relevant for low frequency values closed to the car pitch natural frequency. Finally, some setup proposals are presented to describe what should be done on actual race cars in order to correct vehicle behaviour when friction occurs.

  16. Robotic buildings(s)

    NARCIS (Netherlands)

    Bier, H.H.

    2014-01-01

    Technological and conceptual advances in fields such as artificial intelligence, robotics, and material science have enabled robotic building to be in the last decade prototypically implemented. In this context, robotic building implies both physically built robotic environments and robotically

  17. Chemical origins of frictional aging.

    Science.gov (United States)

    Liu, Yun; Szlufarska, Izabela

    2012-11-02

    Although the basic laws of friction are simple enough to be taught in elementary physics classes and although friction has been widely studied for centuries, in the current state of knowledge it is still not possible to predict a friction force from fundamental principles. One of the highly debated topics in this field is the origin of static friction. For most macroscopic contacts between two solids, static friction will increase logarithmically with time, a phenomenon that is referred to as aging of the interface. One known reason for the logarithmic growth of static friction is the deformation creep in plastic contacts. However, this mechanism cannot explain frictional aging observed in the absence of roughness and plasticity. Here, we discover molecular mechanisms that can lead to a logarithmic increase of friction based purely on interfacial chemistry. Predictions of our model are consistent with published experimental data on the friction of silica.

  18. Roll back malaria update.

    Science.gov (United States)

    1999-10-01

    This article presents the activities under WHO's Roll Back Malaria (RBM) program in Asia, particularly in Nepal, Indonesia, India, Bangladesh, Sri Lanka and the Philippines. In India, the RBM program will start in 5 districts with a major malaria problem. A national committee has been formed by researchers, which will be able to provide operational and strategic support and research expertise in relation to malaria. In Bangladesh, the RBM program was initiated in the sparsely populated hill tract areas of Banderban and Chittagong where access to health care is very poor. At the district level, effective partnerships with private practitioners, politicians, community leaders, school teachers, the press and district Ministry of Health officials are operating to plan for rolling back malaria. In Myanmar, Cambodia, Lao People's Democratic Republic, Yunnan province of China, Vietnam, and Thailand, the focus of the RBM program was to move health care closer to the malaria-infected communities. WHO¿s Global Health Leadership Fellowship Programme, supported by the UN Foundation and Rockefeller Foundation, enables potential leaders to experience the work of UN agencies and contribute to the work of the organization for 2 years. Three out of four persons appointed to the RBM program received prestigious awards: Dr. Paola Marchesini of Brazil; Dr. Tieman Diarra of Mali; and Dr. Bob Taylor of the UK.

  19. Roll-to-roll UV imprint lithography for flexible electronics

    NARCIS (Netherlands)

    Maury, P.; Turkenburg, D.H.; Stroeks, N.; Giesen, P.; Barbu, I.; Meinders, E.R.; Bremen, A. van; Iosad, N.; Werf, R. van der; Onvlee, H.

    2011-01-01

    We propose a roll-to-roll UV imprint lithography tool as a way to pattern flexible PET foil with µm-resolution. As a way to overcome dimensional instability of the foil and its effect on overlay, a self-align approach was investigated, that permits to make several layers in a single lithography

  20. Soft Robotics.

    Science.gov (United States)

    Whitesides, George M

    2018-04-09

    This description of "soft robotics" is not intended to be a conventional review, in the sense of a comprehensive technical summary of a developing field. Rather, its objective is to describe soft robotics as a new field-one that offers opportunities to chemists and materials scientists who like to make "things" and to work with macroscopic objects that move and exert force. It will give one (personal) view of what soft actuators and robots are, and how this class of soft devices fits into the more highly developed field of conventional "hard" robotics. It will also suggest how and why soft robotics is more than simply a minor technical "tweak" on hard robotics and propose a unique role for chemistry, and materials science, in this field. Soft robotics is, at its core, intellectually and technologically different from hard robotics, both because it has different objectives and uses and because it relies on the properties of materials to assume many of the roles played by sensors, actuators, and controllers in hard robotics. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Controlling Tensegrity Robots Through Evolution

    Science.gov (United States)

    Iscen, Atil; Agogino, Adrian; SunSpiral, Vytas; Tumer, Kagan

    2013-01-01

    Tensegrity structures (built from interconnected rods and cables) have the potential to offer a revolutionary new robotic design that is light-weight, energy-efficient, robust to failures, capable of unique modes of locomotion, impact tolerant, and compliant (reducing damage between the robot and its environment). Unfortunately robots built from tensegrity structures are difficult to control with traditional methods due to their oscillatory nature, nonlinear coupling between components and overall complexity. Fortunately this formidable control challenge can be overcome through the use of evolutionary algorithms. In this paper we show that evolutionary algorithms can be used to efficiently control a ball-shaped tensegrity robot. Experimental results performed with a variety of evolutionary algorithms in a detailed soft-body physics simulator show that a centralized evolutionary algorithm performs 400 percent better than a hand-coded solution, while the multi-agent evolution performs 800 percent better. In addition, evolution is able to discover diverse control solutions (both crawling and rolling) that are robust against structural failures and can be adapted to a wide range of energy and actuation constraints. These successful controls will form the basis for building high-performance tensegrity robots in the near future.

  2. Frictional coefficient depending on active friction radius with BPV ...

    African Journals Online (AJOL)

    Frictional coefficient depending on active friction radius with BPV and BTV in automobile disc braking system. ... International Journal of Engineering, Science and Technology. Journal Home · ABOUT ... AJOL African Journals Online. HOW TO ...

  3. Internal friction in uranium

    International Nuclear Information System (INIS)

    Selle, J.E.

    1975-01-01

    Results are presented of studies conducted to relate internal friction measurements in U to allotropic transformations. It was found that several internal friction peaks occur in α-uranium whose magnitude changed drastically after annealing in the β phase. All of the allotropic transformations in uranium are diffusional in nature under slow heating and cooling conditions. Creep at regions of high stress concentration appears to be responsible for high temperature internal friction in α-uranium. The activation energy for grain boundary relaxation in α-uranium was found to be 65.1 +- 4 kcal/mole. Impurity atoms interfere with the basic mechanism for grain boundary relaxation resulting in a distribution in activation energies. A considerable distribution in ln tau 0 was also found which is a measure of the distribution in local order and in the Debye frequency around a grain boundary

  4. LEDs are on a roll

    NARCIS (Netherlands)

    Blom, P.W.M.; Mol, A.M.B. van

    2011-01-01

    Light-emitting diodes are more efficient than conventional lighting, but high production costs limit their uptake. Organic versions that can be produced using a cheap newspaper-style 'roll-to-roll' printing process are likely to revolutionize our lighting and signage, say Paul Blom and Ton van Mol.

  5. Anisotropic constant-roll inflation

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Asuka; Soda, Jiro [Kobe University, Department of Physics, Kobe (Japan)

    2018-01-15

    We study constant-roll inflation in the presence of a gauge field coupled to an inflaton. By imposing the constant anisotropy condition, we find new exact anisotropic constant-roll inflationary solutions which include anisotropic power-law inflation as a special case. We also numerically show that the new anisotropic solutions are attractors in the phase space. (orig.)

  6. Rolling up a Graphene Sheet

    NARCIS (Netherlands)

    Calvaresi, Matteo; Quintana, Mildred; Rudolf, Petra; Zerbetto, Francesco; Prato, Maurizio

    2013-01-01

    Carbon Nanotubes, CNTs, have been described as rolled-up graphene layers. Matching this concept to experiments has been a great experimental challenge for it requires a method to exfoliate graphite, generate ordered and stable dangling carbon bonds, and roll up the layer without affecting the

  7. Rudder roll stabilization for ships

    NARCIS (Netherlands)

    van Amerongen, J.; van der Klugt, P.G.M.; van Nauta lemke, H.R.

    1990-01-01

    This paper describes the design of an autopilot for rudder roll stabilization for ships. This autopilot uses the rudder not only for course keeping but also for reduction of the roll. The system has a series of properties which make the controller design far from straightforward: the process has

  8. The Rolling Transition in a Granular Flow along a Rotating Wall

    Directory of Open Access Journals (Sweden)

    Aurélie Le Quiniou

    2011-11-01

    Full Text Available The flow of a dry granular material composed of spherical particles along a rotating boundary has been studied by the discrete element method (DEM. This type of flow is used, among others, as a process to spread particles. The flow consists of several phases. A compression phase along the rotating wall is followed by an elongation of the flow along the same boundary. Eventually, the particles slide or roll independently along the boundary. We show that the main motion of the flow can be characterized by a complex deformation rate of traction/compression and shear. We define numerically an effective friction coefficient of the flow on the scale of the continuum and show a strong decrease of this effective friction beyond a certain critical friction coefficient μ*. We correlate this phenomenon with the apparition of a new transition from a sliding regime to a rolling without sliding regime that we called the rolling transition; this dynamic transition is controlled by the value of the friction coefficient between the particle and the wall. We show that the spherical shape for the particles may represent an optimum for the flow in terms of energetic.

  9. Computational design of rolling bearings

    CERN Document Server

    Nguyen-Schäfer, Hung

    2016-01-01

    This book comprehensively presents the computational design of rolling bearings dealing with many interdisciplinary difficult working fields. They encompass elastohydrodynamics (EHD), Hertzian contact theory, oil-film thickness in elastohydrodynamic lubrication (EHL), bearing dynamics, tribology of surface textures, fatigue failure mechanisms, fatigue lifetimes of rolling bearings and lubricating greases, Weibull distribution, rotor balancing, and airborne noises (NVH) in the rolling bearings. Furthermore, the readers are provided with hands-on essential formulas based on the up-to-date DIN ISO norms and helpful examples for computational design of rolling bearings. The topics are intended for undergraduate and graduate students in mechanical and material engineering, research scientists, and practicing engineers who want to understand the interactions between these working fields and to know how to design the rolling bearings for automotive industry and many other industries.

  10. Labour market frictions and migration

    NARCIS (Netherlands)

    Cremers, Jan

    2016-01-01

    The 4th contribution to the series INT-AR papers is dedicated to the methods of assessing labour market frictions. The paper provides a (brief) international comparison of the role of labour migration in solving these frictions.

  11. Robotics 101

    Science.gov (United States)

    Sultan, Alan

    2011-01-01

    Robots are used in all kinds of industrial settings. They are used to rivet bolts to cars, to move items from one conveyor belt to another, to gather information from other planets, and even to perform some very delicate types of surgery. Anyone who has watched a robot perform its tasks cannot help but be impressed by how it works. This article…

  12. Vitruvian Robot

    DEFF Research Database (Denmark)

    Hasse, Cathrine

    2017-01-01

    future. A real version of Ava would not last long in a human world because she is basically a solipsist, who does not really care about humans. She cannot co-create the line humans walk along. The robots created as ‘perfect women’ (sex robots) today are very far from the ideal image of Ava...

  13. Robot Teachers

    DEFF Research Database (Denmark)

    Nørgård, Rikke Toft; Ess, Charles Melvin; Bhroin, Niamh Ni

    The world's first robot teacher, Saya, was introduced to a classroom in Japan in 2009. Saya, had the appearance of a young female teacher. She could express six basic emotions, take the register and shout orders like 'be quiet' (The Guardian, 2009). Since 2009, humanoid robot technologies have...... developed. It is now suggested that robot teachers may become regular features in educational settings, and may even 'take over' from human teachers in ten to fifteen years (cf. Amundsen, 2017 online; Gohd, 2017 online). Designed to look and act like a particular kind of human; robot teachers mediate human...... existence and roles, while also aiming to support education through sophisticated, automated, human-like interaction. Our paper explores the design and existential implications of ARTIE, a robot teacher at Oxford Brookes University (2017, online). Drawing on an initial empirical exploration we propose...

  14. Robot vision

    International Nuclear Information System (INIS)

    Hall, E.L.

    1984-01-01

    Almost all industrial robots use internal sensors such as shaft encoders which measure rotary position, or tachometers which measure velocity, to control their motions. Most controllers also provide interface capabilities so that signals from conveyors, machine tools, and the robot itself may be used to accomplish a task. However, advanced external sensors, such as visual sensors, can provide a much greater degree of adaptability for robot control as well as add automatic inspection capabilities to the industrial robot. Visual and other sensors are now being used in fundamental operations such as material processing with immediate inspection, material handling with adaption, arc welding, and complex assembly tasks. A new industry of robot vision has emerged. The application of these systems is an area of great potential

  15. Social Robots

    DEFF Research Database (Denmark)

    Social robotics is a cutting edge research area gathering researchers and stakeholders from various disciplines and organizations. The transformational potential that these machines, in the form of, for example, caregiving, entertainment or partner robots, pose to our societies and to us as indiv......Social robotics is a cutting edge research area gathering researchers and stakeholders from various disciplines and organizations. The transformational potential that these machines, in the form of, for example, caregiving, entertainment or partner robots, pose to our societies and to us...... as individuals seems to be limited by our technical limitations and phantasy alone. This collection contributes to the field of social robotics by exploring its boundaries from a philosophically informed standpoint. It constructively outlines central potentials and challenges and thereby also provides a stable...

  16. Robotic seeding

    DEFF Research Database (Denmark)

    Pedersen, Søren Marcus; Fountas, Spyros; Sørensen, Claus Aage Grøn

    2017-01-01

    Agricultural robotics has received attention for approximately 20 years, but today there are only a few examples of the application of robots in agricultural practice. The lack of uptake may be (at least partly) because in many cases there is either no compelling economic benefit......, or there is a benefit but it is not recognized. The aim of this chapter is to quantify the economic benefits from the application of agricultural robots under a specific condition where such a benefit is assumed to exist, namely the case of early seeding and re-seeding in sugar beet. With some predefined assumptions...... with regard to speed, capacity and seed mapping, we found that among these two technical systems both early seeding with a small robot and re-seeding using a robot for a smaller part of the field appear to be financially viable solutions in sugar beet production....

  17. Friction in sheet metal forming

    DEFF Research Database (Denmark)

    Wiklund, D.; Liljebgren, M.; Berglund, J.

    2010-01-01

    and calls for functional tool surfaces that are durable in these severe tribological conditions. In this study the influence of tool surface topography on friction has been investigated. The frictional response was studied in a Bending Under Tension test. The results did show that a low frictional response...

  18. Intelligent Flow Friction Estimation.

    Science.gov (United States)

    Brkić, Dejan; Ćojbašić, Žarko

    2016-01-01

    Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ). In the present study, a noniterative approach using Artificial Neural Network (ANN) was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re) and the relative roughness of pipe (ε/D) were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re) and the relative roughness (ε/D) ranging between 5000 and 10(8) and between 10(-7) and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  19. Student figures in friction

    DEFF Research Database (Denmark)

    Nielsen, Gritt B.

    , students' room for participation in their own learning, influenced by demands for efficiency, flexibility and student-centred education. The thesis recasts the anthropological endeavour as one of ‘figuration work'. That is, ‘frictional events' are explored as moments when conflicting figures...

  20. Skin tribology: Science friction?

    NARCIS (Netherlands)

    van der Heide, Emile; Zeng, Xiangqiong; Masen, Marc Arthur

    2013-01-01

    The application of tribological knowledge is not just restricted to optimizing mechanical and chemical engineering problems. In fact, effective solutions to friction and wear related questions can be found in our everyday life. An important part is related to skin tribology, as the human skin is

  1. Coulomb Friction Damper

    Science.gov (United States)

    Appleberry, W. T.

    1983-01-01

    Standard hydraulic shock absorber modified to form coulomb (linear friction) damper. Device damps very small velocities and is well suited for use with large masses mounted on soft springs. Damping force is easily adjusted for different loads. Dampers are more reliable than fluid dampers and also more economical to build and to maintain.

  2. Intelligent Flow Friction Estimation

    Directory of Open Access Journals (Sweden)

    Dejan Brkić

    2016-01-01

    Full Text Available Nowadays, the Colebrook equation is used as a mostly accepted relation for the calculation of fluid flow friction factor. However, the Colebrook equation is implicit with respect to the friction factor (λ. In the present study, a noniterative approach using Artificial Neural Network (ANN was developed to calculate the friction factor. To configure the ANN model, the input parameters of the Reynolds Number (Re and the relative roughness of pipe (ε/D were transformed to logarithmic scales. The 90,000 sets of data were fed to the ANN model involving three layers: input, hidden, and output layers with, 2, 50, and 1 neurons, respectively. This configuration was capable of predicting the values of friction factor in the Colebrook equation for any given values of the Reynolds number (Re and the relative roughness (ε/D ranging between 5000 and 108 and between 10−7 and 0.1, respectively. The proposed ANN demonstrates the relative error up to 0.07% which had the high accuracy compared with the vast majority of the precise explicit approximations of the Colebrook equation.

  3. Friction welding method

    International Nuclear Information System (INIS)

    Ishida, Ryuichi; Hatanaka, Tatsuo.

    1969-01-01

    A friction welding method for forming a lattice-shaped base and tie plate supporter for fuel elements is disclosed in which a plate formed with a concavity along its edge is pressure welded to a rotating member such as a boss by longitudinally contacting the projecting surfaces remaining on either side of the concavity with the rotating member during the high speed rotation thereof in the presence of an inert gas. Since only the two projecting surfaces of the plate are fused by friction to the rotary member, heat expansion is absorbed by the concavity to prevent distortion; moreover, a two point contact surface assures a stable fitting and promotes the construction of a rigid lattice in which a number of the abovementioned plates are friction welded between rotating members to form any desired complex arrangement. The inert has serves to protect the material quality of the contacting surfaces from air during the welding step. The present invention thus provides a method in which even Zircaloy may be friction welded in place of casting stainless steel in the construction of supporting lattices to thereby enhance neutron economy. (K. J. Owens)

  4. Micro intelligence robot

    International Nuclear Information System (INIS)

    Jeon, Yon Ho

    1991-07-01

    This book gives descriptions of micro robot about conception of robots and micro robot, match rules of conference of micro robots, search methods of mazes, and future and prospect of robots. It also explains making and design of 8 beat robot like making technique, software, sensor board circuit, and stepping motor catalog, speedy 3, Mr. Black and Mr. White, making and design of 16 beat robot, such as micro robot artist, Jerry 2 and magic art of shortening distances algorithm of robot simulation.

  5. An Intelligent Robot Programing

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Seong Yong

    2012-01-15

    This book introduces an intelligent robot programing with background of the begging, introduction of VPL, and SPL, building of environment for robot platform, starting of robot programing, design of simulation environment, robot autonomy drive control programing, simulation graphic. Such as SPL graphic programing graphical image and graphical shapes, and graphical method application, application of procedure for robot control, robot multiprogramming, robot bumper sensor programing, robot LRF sencor programing and robot color sensor programing.

  6. An Intelligent Robot Programing

    International Nuclear Information System (INIS)

    Hong, Seong Yong

    2012-01-01

    This book introduces an intelligent robot programing with background of the begging, introduction of VPL, and SPL, building of environment for robot platform, starting of robot programing, design of simulation environment, robot autonomy drive control programing, simulation graphic. Such as SPL graphic programing graphical image and graphical shapes, and graphical method application, application of procedure for robot control, robot multiprogramming, robot bumper sensor programing, robot LRF sencor programing and robot color sensor programing.

  7. An eight-legged tactile sensor to estimate coefficient of static friction.

    Science.gov (United States)

    Wei Chen; Rodpongpun, Sura; Luo, William; Isaacson, Nathan; Kark, Lauren; Khamis, Heba; Redmond, Stephen J

    2015-08-01

    It is well known that a tangential force larger than the maximum static friction force is required to initiate the sliding motion between two objects, which is governed by a material constant called the coefficient of static friction. Therefore, knowing the coefficient of static friction is of great importance for robot grippers which wish to maintain a stable and precise grip on an object during various manipulation tasks. Importantly, it is most useful if grippers can estimate the coefficient of static friction without having to explicitly explore the object first, such as lifting the object and reducing the grip force until it slips. A novel eight-legged sensor, based on simplified theoretical principles of friction is presented here to estimate the coefficient of static friction between a planar surface and the prototype sensor. Each of the sensor's eight legs are straight and rigid, and oriented at a specified angle with respect to the vertical, allowing it to estimate one of five ranges (5 = 8/2 + 1) that the coefficient of static friction can occupy. The coefficient of friction can be estimated by determining whether the legs have slipped or not when pressed against a surface. The coefficients of static friction between the sensor and five different materials were estimated and compared to a measurement from traditional methods. A least-squares linear fit of the sensor estimated coefficient showed good correlation with the reference coefficient with a gradient close to one and an r(2) value greater than 0.9.

  8. Indentation versus Rolling: Dependence of Adhesion on Contact Geometry for Biomimetic Structures.

    Science.gov (United States)

    Moyle, Nichole; He, Zhenping; Wu, Haibin; Hui, Chung-Yuen; Jagota, Anand

    2018-04-03

    Numerous biomimetic structures made from elastomeric materials have been developed to produce enhancement in properties such as adhesion, static friction, and sliding friction. As a property, one expects adhesion to be represented by an energy per unit area that is usually sensitive to the combination of shear and normal stresses at the crack front but is otherwise dependent only on the two elastic materials that meet at the interface. More specifically, one would expect that adhesion measured by indentation (a popular and convenient technique) could be used to predict adhesion hysteresis in the more practically important rolling geometry. Previously, a structure with a film-terminated fibrillar geometry exhibited dramatic enhancement of adhesion by a crack-trapping mechanism during indentation with a rigid sphere. Roughly isotropic structures such as the fibrillar geometry show a strong correlation between adhesion enhancement in indentation versus adhesion hysteresis in rolling. However, anisotropic structures, such as a film-terminated ridge-channel geometry, surprisingly show a dramatic divergence between adhesion measured by indentation versus rolling. We study this experimentally and theoretically, first comparing the adhesion of the anisotropic ridge-channel structure to the roughly isotropic fibrillar structure during indentation with a rigid sphere, where only the isotropic structure shows adhesion enhancement. Second, we examine in more detail the anomalous anisotropic film-terminated ridge-channel structure during indentation with a rigid sphere versus rolling to show why these structures show a dramatic adhesion enhancement for the rolling case and no adhesion enhancement for indentation.

  9. A comparative study of roll compaction of free-flowing and cohesive pharmaceutical powders.

    Science.gov (United States)

    Yu, Shen; Gururajan, Bindhu; Reynolds, Gavin; Roberts, Ron; Adams, Michael J; Wu, Chuan-Yu

    2012-05-30

    Roll compaction is widely adopted as a dry granulation method in the pharmaceutical industry. The roll compaction behaviour of feed powders is primarily governed by two parameters: the maximum pressure and the nip angle. Although the maximum pressure can be measured directly using pressure sensors fitted in the rolls, it is not a trivial task to determine the nip angle, which is a measure of the size of the compaction zone and hence the degree of compression. Thus a robust approach based upon the calculation of the pressure gradient, which can be obtained directly from experiments using an instrumented roll compactor, was developed. It has been shown that the resulting nip angles are comparable to those obtained using the methods reported in literature. Nevertheless, the proposed approach has distinctive advantages including (1) it is based on the intrinsic features of slip and no-slip interactions between the powder and roll surface and (2) it is not necessary to carry out wall friction measurements that involve plates that may not be representative of the roll compactor in terms of the surface topography and surface energy. The method was evaluated by investigating the effect of roll speed for two pharmaceutical excipients with distinctive material properties: microcrystalline cellulose (MCC) and di-calcium phosphate dihydrate (DCPD). It was found that the maximum pressure and nip angle for DCPD, which is a cohesive powder, decrease sharply with increasing roll speed whereas they are essentially independent of roll speed for MCC, which is an easy flowing powder. The roll compaction behaviour of MCC-DCPD mixtures with various compositions was also investigated in order to evaluate the effect of flowability. It was found that the nip angle and maximum pressure generally increased with improved flowability of the feed powders. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. PEBBLES Simulation of Static Friction and New Static Friction Benchmark

    International Nuclear Information System (INIS)

    Cogliati, Joshua J.; Ougouag, Abderrafi M.

    2010-01-01

    Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

  11. Robust Feedback Linearization-based Control Design for a Wheeled Mobile Robot

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Andersen, Palle; Pedersen, Tom Søndergaard

    This paper considers the trajectory tracking problem for a four-wheel driven, four-wheel steered mobile robot moving in outdoor terrain. The robot is modeled as a non-holonomic dynamic system subject to pure rolling, no-slip constraints. A nonlinear trajectory tracking feedback control law based...

  12. Internal rotor friction instability

    Science.gov (United States)

    Walton, J.; Artiles, A.; Lund, J.; Dill, J.; Zorzi, E.

    1990-01-01

    The analytical developments and experimental investigations performed in assessing the effect of internal friction on rotor systems dynamic performance are documented. Analytical component models for axial splines, Curvic splines, and interference fit joints commonly found in modern high speed turbomachinery were developed. Rotor systems operating above a bending critical speed were shown to exhibit unstable subsynchronous vibrations at the first natural frequency. The effect of speed, bearing stiffness, joint stiffness, external damping, torque, and coefficient of friction, was evaluated. Testing included material coefficient of friction evaluations, component joint quantity and form of damping determinations, and rotordynamic stability assessments. Under conditions similar to those in the SSME turbopumps, material interfaces experienced a coefficient of friction of approx. 0.2 for lubricated and 0.8 for unlubricated conditions. The damping observed in the component joints displayed nearly linear behavior with increasing amplitude. Thus, the measured damping, as a function of amplitude, is not represented by either linear or Coulomb friction damper models. Rotordynamic testing of an axial spline joint under 5000 in.-lb of static torque, demonstrated the presence of an extremely severe instability when the rotor was operated above its first flexible natural frequency. The presence of this instability was predicted by nonlinear rotordynamic time-transient analysis using the nonlinear component model developed under this program. Corresponding rotordynamic testing of a shaft with an interference fit joint demonstrated the presence of subsynchronous vibrations at the first natural frequency. While subsynchronous vibrations were observed, they were bounded and significantly lower in amplitude than the synchronous vibrations.

  13. Robot dispatching Scenario for Accident Condition Monitoring of NPP

    International Nuclear Information System (INIS)

    Kim, Jongseog

    2013-01-01

    In March of 2011, unanticipated big size of tsunami attacks Fukushima NPP, this accident results in explosion of containment building. Tokyo electric power of Japan couldn't dispatch a robot for monitoring of containment inside. USA Packbot robot used for desert war in Iraq was supplied to Fukushima NPP for monitoring of high radiation area. Packbot also couldn't reach deep inside of Fukushima NPP due to short length of power cable. Japanese robot 'Queens' also failed to complete a mission due to communication problem between robot and operator. I think major reason of these robot failures is absence of robot dispatching scenario. If there was a scenario and a rehearsal for monitoring during or after accident, these unanticipated obstacles could be overcome. Robot dispatching scenario studied for accident of nuclear power plant was described herein. Study on scenario of robot dispatching is performed. Flying robot is regarded as good choice for accident monitoring. Walking robot with arm equipped is good for emergency valve close. Short time work and shift work by several robots can be a solution for high radiation area. Thin and soft cable with rolling reel can be a good solution for long time work and good communication

  14. Stress and accidental defect detection on rolling mill rolls

    International Nuclear Information System (INIS)

    Auzas, J.-D.

    1999-01-01

    During the rolling mill process, rolls are submitted to high pressures that can lead to local decohesion or metallurgical changes. Both these cracks or softened areas must be detected as soon as they appear because of the risk of spalling, marks on the product, and mill wreck. These defects can be detected using the eddy current method, and particularly sensors specially developed for micro-defects detection. These sensors must be adapted to the environment of a roll grinding machine on which they must be installed. Users' schedule of conditions also require them to be attached to a wide range of eddy current generator and automatic computerized interpretation. Mill requirements for new high tech roll grades and quality lead to continuous development and improvement of the tools that will provide immediate 'go - no go' information. This paper is an update of these developments. (author)

  15. Characterization of a hot-rolled Cu--Al--Ni--Ti shape memory alloy

    International Nuclear Information System (INIS)

    Segui, C.; Pons, J.; Cesari, E.

    1999-01-01

    The changes in the martensitic transformation of a Cu-Al-Ni-Ti alloy hot-rolled at different temperatures have been studied in detail, covering different aspects such as ageing in the parent phase at temperatures ranging between 250 and 350 o C, stabilisation of the martensite and betatization of the previously hot-rolled specimens. Besides the evolution of transformation temperatures upon different thermal treatments, special attention has been paid to the changes in mechanical properties of the alloy, such as elastic modulus and internal friction. These results are analysed in relation to the microstructural changes as observed by transmission electron microscopy. (orig.)

  16. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... of the cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  17. Manufacturing Demonstration Facility: Roll-to-Roll Processing

    Energy Technology Data Exchange (ETDEWEB)

    Datskos, Panos G [ORNL; Joshi, Pooran C [ORNL; List III, Frederick Alyious [ORNL; Duty, Chad E [ORNL; Armstrong, Beth L [ORNL; Ivanov, Ilia N [ORNL; Jacobs, Christopher B [ORNL; Graham, David E [ORNL; Moon, Ji Won [ORNL

    2015-08-01

    This Manufacturing Demonstration Facility (MDF)e roll-to-roll processing effort described in this report provided an excellent opportunity to investigate a number of advanced manufacturing approaches to achieve a path for low cost devices and sensors. Critical to this effort is the ability to deposit thin films at low temperatures using nanomaterials derived from nanofermentation. The overarching goal of this project was to develop roll-to-roll manufacturing processes of thin film deposition on low-cost flexible substrates for electronics and sensor applications. This project utilized ORNL s unique Pulse Thermal Processing (PTP) technologies coupled with non-vacuum low temperature deposition techniques, ORNL s clean room facility, slot dye coating, drop casting, spin coating, screen printing and several other equipment including a Dimatix ink jet printer and a large-scale Kyocera ink jet printer. The roll-to-roll processing project had three main tasks: 1) develop and demonstrate zinc-Zn based opto-electronic sensors using low cost nanoparticulate structures manufactured in a related MDF Project using nanofermentation techniques, 2) evaluate the use of silver based conductive inks developed by project partner NovaCentrix for electronic device fabrication, and 3) demonstrate a suite of low cost printed sensors developed using non-vacuum deposition techniques which involved the integration of metal and semiconductor layers to establish a diverse sensor platform technology.

  18. Foucault dissipation in a rolling cylinder: a webcam quantitative study

    International Nuclear Information System (INIS)

    Bonanno, A; Bozzo, G; Camarca, M; Sapia, P

    2011-01-01

    In this paper we present an experimental strategy to measure the micro power dissipation due to Foucault 'eddy' currents in a copper cylinder rolling on two parallel conductive rails in the presence of a magnetic field. Foucault power dissipation is obtained from kinematical measurements carried out by using a common PC webcam and video analysis done by means of software tools freely available within Windows operating system (Paint and Movie Maker). The proposed method allows us to experimentally discern the contribution to dissipation due to the velocity-independent rolling friction from that owed to the viscous-like friction emerging from complex electrodynamic interactions among eddy currents and the external magnetic field. In this way a microdissipation of some tens of μW is measured. The easily reproducible experimental setup, the simple implementation of data analysis and the discussion on various experimental approaches and strategies make the proposed activity highly significant for university undergraduates, since involved crucial skills can be efficiently strengthened.

  19. Foucault dissipation in a rolling cylinder: a webcam quantitative study

    Energy Technology Data Exchange (ETDEWEB)

    Bonanno, A; Bozzo, G; Camarca, M; Sapia, P, E-mail: sapia@fis.unical.it [Physics Department, University of Calabria, I-87036 Rende, CS (Italy)

    2011-03-15

    In this paper we present an experimental strategy to measure the micro power dissipation due to Foucault 'eddy' currents in a copper cylinder rolling on two parallel conductive rails in the presence of a magnetic field. Foucault power dissipation is obtained from kinematical measurements carried out by using a common PC webcam and video analysis done by means of software tools freely available within Windows operating system (Paint and Movie Maker). The proposed method allows us to experimentally discern the contribution to dissipation due to the velocity-independent rolling friction from that owed to the viscous-like friction emerging from complex electrodynamic interactions among eddy currents and the external magnetic field. In this way a microdissipation of some tens of {mu}W is measured. The easily reproducible experimental setup, the simple implementation of data analysis and the discussion on various experimental approaches and strategies make the proposed activity highly significant for university undergraduates, since involved crucial skills can be efficiently strengthened.

  20. Two-legged walking robot prescribed motion on a rough cylinder

    Science.gov (United States)

    Golubev, Yury; Melkumova, Elena

    2018-05-01

    The motion of a walking robot with n legs, that ensure the desired motion of the robot body, is described using general dynamics theoretical framework. When each of the robot legs contacts the surface in a single foothold, the momentum and angular momentum theorems yield a system of six differential equations that form a complete description of the robot motion. In the case of two-leg robot (n = 2) the problem of the existence of the solution can be reduced to a system of algebraic inequalities. Using numerical analysis, the classification of footholds positions for different values of the friction coefficient is obtained.

  1. Rolling Process Modeling Report: Finite-Element Prediction of Roll Separating Force and Rolling Defects

    Energy Technology Data Exchange (ETDEWEB)

    Soulami, Ayoub [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Paxton, Dean M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burkes, Douglas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-04-23

    Pacific Northwest National Laboratory (PNNL) has been investigating manufacturing processes for the uranium-10% molybdenum (U-10Mo) alloy plate-type fuel for the U.S. high-performance research reactors. This work supports the Convert Program of the U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA) Global Threat Reduction Initiative. This report documents modeling results of PNNL’s efforts to perform finite-element simulations to predict roll separating forces and rolling defects. Simulations were performed using a finite-element model developed using the commercial code LS-Dyna. Simulations of the hot rolling of U-10Mo coupons encapsulated in low-carbon steel have been conducted following two different schedules. Model predictions of the roll-separation force and roll-pack thicknesses at different stages of the rolling process were compared with experimental measurements. This report discusses various attributes of the rolled coupons revealed by the model (e.g., dog-boning and thickness non-uniformity).

  2. Systematics of constant roll inflation

    Science.gov (United States)

    Anguelova, Lilia; Suranyi, Peter; Wijewardhana, L. C. R.

    2018-02-01

    We study constant roll inflation systematically. This is a regime, in which the slow roll approximation can be violated. It has long been thought that this approximation is necessary for agreement with observations. However, recently it was understood that there can be inflationary models with a constant, and not necessarily small, rate of roll that are both stable and compatible with the observational constraint ns ≈ 1. We investigate systematically the condition for such a constant-roll regime. In the process, we find a whole new class of inflationary models, in addition to the known solutions. We show that the new models are stable under scalar perturbations. Finally, we find a part of their parameter space, in which they produce a nearly scale-invariant scalar power spectrum, as needed for observational viability.

  3. Space Robotics Challenge

    Data.gov (United States)

    National Aeronautics and Space Administration — The Space Robotics Challenge seeks to infuse robot autonomy from the best and brightest research groups in the robotics community into NASA robots for future...

  4. Grease lubrication in rolling bearings

    CERN Document Server

    Lugt, Piet M

    2012-01-01

    The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

  5. Robotic arm

    International Nuclear Information System (INIS)

    Kwech, H.

    1989-01-01

    A robotic arm positionable within a nuclear vessel by access through a small diameter opening and having a mounting tube supported within the vessel and mounting a plurality of arm sections for movement lengthwise of the mounting tube as well as for movement out of a window provided in the wall of the mounting tube is disclosed. An end effector, such as a grinding head or welding element, at an operating end of the robotic arm, can be located and operated within the nuclear vessel through movement derived from six different axes of motion provided by mounting and drive connections between arm sections of the robotic arm. The movements are achieved by operation of remotely-controllable servo motors, all of which are mounted at a control end of the robotic arm to be outside the nuclear vessel. 23 figs

  6. Robotic surgery

    Science.gov (United States)

    ... with this type of surgery give it some advantages over standard endoscopic techniques. The surgeon can make ... Elsevier Saunders; 2015:chap 87. Muller CL, Fried GM. Emerging technology in surgery: Informatics, electronics, robotics. In: ...

  7. Robotic parathyroidectomy.

    Science.gov (United States)

    Okoh, Alexis Kofi; Sound, Sara; Berber, Eren

    2015-09-01

    Robotic parathyroidectomy has recently been described. Although the procedure eliminates the neck scar, it is technically more demanding than the conventional approaches. This report is a review of the patients' selection criteria, technique, and outcomes. © 2015 Wiley Periodicals, Inc.

  8. Light Robotics

    DEFF Research Database (Denmark)

    Glückstad, Jesper; Palima, Darwin

    Light Robotics - Structure-Mediated Nanobiophotonics covers the latest means of sculpting of both light and matter for achieving bioprobing and manipulation at the smallest scales. The synergy between photonics, nanotechnology and biotechnology spans the rapidly growing field of nanobiophotonics...

  9. Robotic arm

    Science.gov (United States)

    Kwech, Horst

    1989-04-18

    A robotic arm positionable within a nuclear vessel by access through a small diameter opening and having a mounting tube supported within the vessel and mounting a plurality of arm sections for movement lengthwise of the mounting tube as well as for movement out of a window provided in the wall of the mounting tube. An end effector, such as a grinding head or welding element, at an operating end of the robotic arm, can be located and operated within the nuclear vessel through movement derived from six different axes of motion provided by mounting and drive connections between arm sections of the robotic arm. The movements are achieved by operation of remotely-controllable servo motors, all of which are mounted at a control end of the robotic arm to be outside the nuclear vessel.

  10. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

  11. Fuzzy-Genetic Optimal Control for Four Degreeof Freedom Robotic Arm Movement

    OpenAIRE

    V. K. Banga; R. Kumar; Y. Singh

    2009-01-01

    In this paper, we present optimal control for movement and trajectory planning for four degrees-of-freedom robot using Fuzzy Logic (FL) and Genetic Algorithms (GAs). We have evaluated using Fuzzy Logic (FL) and Genetic Algorithms (GAs) for four degree-of-freedom (4 DOF) robotics arm, Uncertainties like; Movement, Friction and Settling Time in robotic arm movement have been compensated using Fuzzy logic and Genetic Algorithms. The development of a fuzzy genetic optimizatio...

  12. Rolling Resistance Measurement and Model Development

    DEFF Research Database (Denmark)

    Andersen, Lasse Grinderslev; Larsen, Jesper; Fraser, Elsje Sophia

    2015-01-01

    There is an increased focus worldwide on understanding and modeling rolling resistance because reducing the rolling resistance by just a few percent will lead to substantial energy savings. This paper reviews the state of the art of rolling resistance research, focusing on measuring techniques, s......, surface and texture modeling, contact models, tire models, and macro-modeling of rolling resistance...

  13. Purwarupa Sistem Integrasi Quadcopter dan Mobile Robot

    OpenAIRE

    Dharmawan, Andi; Lusiarta Putera, Christian Antonia

    2012-01-01

    AbstrakQuadcopter, juga dikenal sebagai quadrotor, adalah helikopter dengan empat motor yang dilengkapi dengan  empat buah propeller pada masing-masing motornya yang digunakan untuk terbang dan bermanuver. Pada quadcopter terdapat 3 variabel sudut yang menjadi element utama dalam pengendaliannya yaitu roll, pitch, dan yaw yang diperoleh dari penggabungan sensor accelerometer, gyroscope dan magnetometer dengan metode Direction Cosine Matrix. Pada sistem integrasi mobile robot dan quadcopter, d...

  14. Effect of Friction Model and Tire Maneuvering on Tire-Pavement Contact Stress

    Directory of Open Access Journals (Sweden)

    Haichao Zhou

    2015-01-01

    Full Text Available This paper aims to simulate the effects of different friction models on tire braking. A truck radial tire (295/80R22.5 was modeled and the model was validated with tire deflection. An exponential decay friction model that considers the effect of sliding velocity on friction coefficients was adopted for analyzing braking performance. The result shows that the exponential decay friction model used for evaluating braking ability meets design requirements of antilock braking system (ABS. The tire-pavement contact stress characteristics at various driving conditions (static, free rolling, braking, camber, and cornering were analyzed. It is found that the change of driving conditions has direct influence on tire-pavement contact stress distribution. The results provide the guidance for tire braking performance evaluation.

  15. Bioinspired orientation-dependent friction.

    Science.gov (United States)

    Xue, Longjian; Iturri, Jagoba; Kappl, Michael; Butt, Hans-Jürgen; del Campo, Aránzazu

    2014-09-23

    Spatular terminals on the toe pads of a gecko play an important role in directional adhesion and friction required for reversible attachment. Inspired by the toe pad design of a gecko, we study friction of polydimethylsiloxane (PDMS) micropillars terminated with asymmetric (spatular-shaped) overhangs. Friction forces in the direction of and against the spatular end were evaluated and compared to friction forces on symmetric T-shaped pillars and pillars without overhangs. The shape of friction curves and the values of friction forces on spatula-terminated pillars were orientation-dependent. Kinetic friction forces were enhanced when shearing against the spatular end, while static friction was stronger in the direction toward the spatular end. The overall friction force was higher in the direction against the spatula end. The maximum value was limited by the mechanical stability of the overhangs during shear. The aspect ratio of the pillar had a strong influence on the magnitude of the friction force, and its contribution surpassed and masked that of the spatular tip for aspect ratios of >2.

  16. Recent advances in robotics

    International Nuclear Information System (INIS)

    Beni, G.; Hackwood, S.

    1984-01-01

    Featuring 10 contributions, this volume offers a state-of-the-art report on robotic science and technology. It covers robots in modern industry, robotic control to help the disabled, kinematics and dynamics, six-legged walking robots, a vector analysis of robot manipulators, tactile sensing in robots, and more

  17. Identification of GMS friction model without friction force measurement

    International Nuclear Information System (INIS)

    Grami, Said; Aissaoui, Hicham

    2011-01-01

    This paper deals with an online identification of the Generalized Maxwell Slip (GMS) friction model for both presliding and sliding regime at the same time. This identification is based on robust adaptive observer without friction force measurement. To apply the observer, a new approach of calculating the filtered friction force from the measurable signals is introduced. Moreover, two approximations are proposed to get the friction model linear over the unknown parameters and an approach of suitable filtering is introduced to guarantee the continuity of the model. Simulation results are presented to prove the efficiency of the approach of identification.

  18. Perancangan Lengan Robot 5 Derajat Kebebasan Dengan Pendekatan Kinematika

    Directory of Open Access Journals (Sweden)

    - Firmansyah

    2014-10-01

    Full Text Available This study discusses the design of arm robot model with 5 degree of freedom that is designed to be a small-scale model of the articulated robot industry to simulate the movement of the robots industry. The objective of this research is to build a real arm robot based on kinematic aspects with the movement of waist, shoulder, elbow, wrist pitch, wrist roll and gripper, and to analyze the robot movement. The design includes building the real arm robot based on Arduino Uno board controller and the movement of the robot using servo motor DC. The robot  can be controlled automatically from the computer with the RS-232 or USB port interface and it learns about the kinematic of the robot’s arm when an experiment on the forward kinematic is accomplished. The robot was running well, with the maximum distance that can be reached by the robot on the coordinate axis  x = 425 mm, y = 425 mm and  z = 480 mm.

  19. Small-scale soft-bodied robot with multimodal locomotion

    Science.gov (United States)

    Hu, Wenqi; Lum, Guo Zhan; Mastrangeli, Massimo; Sitti, Metin

    2018-02-01

    Untethered small-scale (from several millimetres down to a few micrometres in all dimensions) robots that can non-invasively access confined, enclosed spaces may enable applications in microfactories such as the construction of tissue scaffolds by robotic assembly, in bioengineering such as single-cell manipulation and biosensing, and in healthcare such as targeted drug delivery and minimally invasive surgery. Existing small-scale robots, however, have very limited mobility because they are unable to negotiate obstacles and changes in texture or material in unstructured environments. Of these small-scale robots, soft robots have greater potential to realize high mobility via multimodal locomotion, because such machines have higher degrees of freedom than their rigid counterparts. Here we demonstrate magneto-elastic soft millimetre-scale robots that can swim inside and on the surface of liquids, climb liquid menisci, roll and walk on solid surfaces, jump over obstacles, and crawl within narrow tunnels. These robots can transit reversibly between different liquid and solid terrains, as well as switch between locomotive modes. They can additionally execute pick-and-place and cargo-release tasks. We also present theoretical models to explain how the robots move. Like the large-scale robots that can be used to study locomotion, these soft small-scale robots could be used to study soft-bodied locomotion produced by small organisms.

  20. Effect of Carbon Content on the Properties of Iron-Based Powder Metallurgical Parts Produced by the Surface Rolling Process

    Directory of Open Access Journals (Sweden)

    Yan Zhao

    2018-01-01

    Full Text Available In recent years, the rolling densification process has become increasingly widely used to strengthen powder metallurgy parts. The original composition of the rolled powder metallurgy blank has a significant effect on the rolling densification technology. The present work investigated the effects of different carbon contents (0 wt. %, 0.2 wt. %, 0.45 wt. %, and 0.8 wt. % on the rolling densification. The selection of the raw materials in the surface rolling densification process was analyzed based on the pore condition, structure, hardness, and friction performance of the materials. The results show that the 0.8 wt. % carbon content of the surface rolling material can effectively improve the properties of iron-based powder metallurgy parts. The samples with 0.8 wt. % carbon have the highest surface hardness (340 HV0.1 and the lowest surface friction coefficient (0.35. Even if the dense layer depth is 1.13 mm, which is thinner than other samples with low carbon content, it also meets the requirements for powder metallurgy parts such as gears used in the auto industry.

  1. Marinization concept for the TRICEPT TR600 robot

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, A.; Aust, E.; Niemann, H.R.; Santos, J.F. dos [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung; Hammerin, R.; Neumann, K.E. [Neos Robotics AB, Taeby (Sweden); Gibson, D. [National Hyperbaric Centre, Aberdeen (United Kingdom)

    1998-11-01

    The need for automated welding repair systems of marine structures, ship hulls and nuclear installations had lead to an increasing demand for subsea robots. Considering the application of friction welding to perform underwater repairs, a TRICEPT TR600 robot has been identified as the most suitable system to withstand the high reaction forces characteristic of this process. This study reviews initially the research and development work carried out at GKSS to modify and test a Siemens-MANUTEC robot. After a description of the TRICEPT TR600 robot a marinization concept is presented and discussed in detail. Problems of galvanic corrosion in seawater are addressed in a separate chapter. The deflection of the robot in subsea water currents is estimated with a worst-case calculation. (orig.) [Deutsch] Der Wunsch, Roboter auch unter Wasser einsetzen zu koennen, waechst mit steigendem Interesse nach automatisierten Schweissverfahren fuer Reparaturen an marinen Bauwerken, Schiffsruempfen und in Kernenergieanlagen. Fuer den Einsatz von Reibschweissverfahren fuer diese Reparaturen wurde der TRICEPT TR600-Roboter ausgewaehlt, da dieser auch den charakteristisch hohen Prozesskraeften widerstehen kann. Die notwendigen Modifikationen und Pruefungen werden beispielhaft anhand des bei der GKSS modifizierten Siemens-MANUTEC-Roboters vorgestellt. Nach einer Beschreibung des TRICEPT-Roboters werden die notwendigen Umbaumassnahmen detailliert dargestellt und diskutiert. Auf die Problematik der galvanischen Korrosion in Seewasser wird in einem gesonderten Kapitel naeher eingegangen. Zusaetzlich wird eine moegliche Ablenkung des Roboters durch Wasserstroemung ueberschlaegig berechnet. (orig.)

  2. Friction surfaced Stellite6 coatings

    International Nuclear Information System (INIS)

    Rao, K. Prasad; Damodaram, R.; Rafi, H. Khalid; Ram, G.D. Janaki; Reddy, G. Madhusudhan; Nagalakshmi, R.

    2012-01-01

    Solid state Stellite6 coatings were deposited on steel substrate by friction surfacing and compared with Stellite6 cast rod and coatings deposited by gas tungsten arc and plasma transferred arc welding processes. Friction surfaced coatings exhibited finer and uniformly distributed carbides and were characterized by the absence of solidification structure and compositional homogeneity compared to cast rod, gas tungsten arc and plasma transferred coatings. Friction surfaced coating showed relatively higher hardness. X-ray diffraction of samples showed only face centered cubic Co peaks while cold worked coating showed hexagonally close packed Co also. - Highlights: ► Stellite6 used as coating material for friction surfacing. ► Friction surfaced (FS) coatings compared with casting, GTA and PTA processes. ► Finer and uniformly distributed carbides in friction surfaced coatings. ► Absence of melting results compositional homogeneity in FS Stellite6 coatings.

  3. Jamming transition in a two-dimensional open granular pile with rolling resistance

    Directory of Open Access Journals (Sweden)

    Caio F. M. Magalhães

    2014-10-01

    Full Text Available We present a molecular dynamics study of the jamming/unjamming transition in two-dimensional granular piles with open boundaries. The grains are modeled by viscoelastic forces, Coulomb friction and resistance to rolling. Two models for the rolling resistance interaction were assessed: one considers a constant rolling friction coefficient, and the other one a strain dependent coefficient. The piles are grown on a finite size substrate and subsequently discharged through an orifice opened at the center of the substrate. Varying the orifice width and taking the final height of the pile after the discharge as the order parameter, one can devise a transition from a jammed regime (when the grain flux is always clogged by an arch to a catastrophic regime, in which the pile is completely destroyed by an avalanche as large as the system size. A finite size analysis shows that there is a finite orifice width associated with the threshold for the unjamming transition, no matter the model used for the microscopic interactions. As expected, the value of this threshold width increases when rolling resistance is considered, and it depends on the model used for the rolling friction. Received: 14 June 2014, Accepted: 7 October 2014; Reviewed by: R. Arévalo, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore; Edited by: L. A. Pugnaloni; DOI: http://dx.doi.org/10.4279/PIP.060007 Cite as: C F M. Magalhaes, A P F Atman, G Combe, J G Moreira, Papers in Physics 6, 060007 (2014

  4. Micromechanical study of macroscopic friction and dissipation in idealised granular materials: the effect of interparticle friction

    NARCIS (Netherlands)

    Kruyt, Nicolaas P.; Gutkowski, Witold; Rothenburg, L.; Kowalewski, Tomasz A.

    2004-01-01

    Using Discrete Element Method (DEM) simulations with varying interparticle friction coefficient, the relation between interparticle friction coefficient and macroscopic continuum friction and dissipation is investigated. As expected, macroscopic friction and dilatancy increase with interparticle

  5. The effect of roll gap geometry on microstructure in cold-rolled aluminum

    DEFF Research Database (Denmark)

    Mishin, Oleg; Bay, B.; Winther, G.

    2004-01-01

    Microstructure and texture are analyzed through the thickness of two aluminum plates cold-rolled 40% with different roll gap geometries. It is found that both texture and microstructure are strongly affected by the rolling geometry. After rolling with intermediate-size draughts a rolling-type tex......Microstructure and texture are analyzed through the thickness of two aluminum plates cold-rolled 40% with different roll gap geometries. It is found that both texture and microstructure are strongly affected by the rolling geometry. After rolling with intermediate-size draughts a rolling...... layers. In these layers, extended planar dislocation boundaries are frequently found to be inclined closely to the rolling direction. The subsurface and central layers of this plate exhibit microstructures similar to those in the plate rolled with intermediate draughts. It is suggested...

  6. Reactive boundary layers in metallic rolling contacts

    Energy Technology Data Exchange (ETDEWEB)

    Burbank, John

    2016-05-01

    of the treated materials. The second pre-conditioning method involved the targeted generation of chemically reactive tribolayers (tribofilms) on twin disk testing rigs. The lubrication strategies were based on: a. CaCO{sub 3}, which is predominant in engine oils, and b. MoDTC, which is commonly used in engine and gear oils. The films generated in pre-conditioning were analyzed by SEM-EDX with Element-Mapping, Raman spectroscopy, and XPS to elucidate their molecular composition and concentration on the sample surfaces. The combination of these methods of analysis gave a clear indication that 10{sup 4} cycles were sufficient to generate stable and lasting tribofilms. CaO and CaCO{sub 3} were the main components of the tribofilm from the first lubricant package, while MoS{sub 2}, MoO{sub 2} and MoO{sub 3} were the main components from the second lubricant package. Finally, slip-rolling endurance testing (T = +120 C, 10{sup 7} cycles, approximately 19 days in a factory fill engine oil) was carried out on all materials. It was shown that both pre-conditioning methods could achieve significant reductions in friction and wear during testing at up to and including P{sub 0Mean} =1.94 GPa (P{sub 0Max} = 2.91 GPa, F{sub N} = 2,000 N). Ultimately, this research showed that: 1. non-case-hardened high-performance steels offer competitive wear performance and better friction behaviour than the case-hardened 20MnCr5. 2. pre-conditioning led to COF reductions to under 7/10 and wear coefficient reductions to an astonishing 1/10 of the original values for the untreated steels under mixed/boundary lubrication. 3. the observed improvements to friction behaviour and wear performance are indicative of a technically simple, cost- and energy-efficient pre-conditioning strategy that may prove an appropriate substitute for existing thermochemical treatments for steel alloys.

  7. Reactive boundary layers in metallic rolling contacts

    International Nuclear Information System (INIS)

    Burbank, John

    2016-01-01

    treated materials. The second pre-conditioning method involved the targeted generation of chemically reactive tribolayers (tribofilms) on twin disk testing rigs. The lubrication strategies were based on: a. CaCO 3 , which is predominant in engine oils, and b. MoDTC, which is commonly used in engine and gear oils. The films generated in pre-conditioning were analyzed by SEM-EDX with Element-Mapping, Raman spectroscopy, and XPS to elucidate their molecular composition and concentration on the sample surfaces. The combination of these methods of analysis gave a clear indication that 10 4 cycles were sufficient to generate stable and lasting tribofilms. CaO and CaCO 3 were the main components of the tribofilm from the first lubricant package, while MoS 2 , MoO 2 and MoO 3 were the main components from the second lubricant package. Finally, slip-rolling endurance testing (T = +120 C, 10 7 cycles, approximately 19 days in a factory fill engine oil) was carried out on all materials. It was shown that both pre-conditioning methods could achieve significant reductions in friction and wear during testing at up to and including P 0Mean =1.94 GPa (P 0Max = 2.91 GPa, F N = 2,000 N). Ultimately, this research showed that: 1. non-case-hardened high-performance steels offer competitive wear performance and better friction behaviour than the case-hardened 20MnCr5. 2. pre-conditioning led to COF reductions to under 7/10 and wear coefficient reductions to an astonishing 1/10 of the original values for the untreated steels under mixed/boundary lubrication. 3. the observed improvements to friction behaviour and wear performance are indicative of a technically simple, cost- and energy-efficient pre-conditioning strategy that may prove an appropriate substitute for existing thermochemical treatments for steel alloys.

  8. Argo packing friction research update

    International Nuclear Information System (INIS)

    VanTassell, D.M.

    1994-01-01

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  9. Friction and wear calculation methods

    CERN Document Server

    Kragelsky, I V; Kombalov, V S

    1981-01-01

    Friction and Wear: Calculation Methods provides an introduction to the main theories of a new branch of mechanics known as """"contact interaction of solids in relative motion."""" This branch is closely bound up with other sciences, especially physics and chemistry. The book analyzes the nature of friction and wear, and some theoretical relationships that link the characteristics of the processes and the properties of the contacting bodies essential for practical application of the theories in calculating friction forces and wear values. The effect of the environment on friction and wear is a

  10. Soft Robotics Week

    CERN Document Server

    Rossiter, Jonathan; Iida, Fumiya; Cianchetti, Matteo; Margheri, Laura

    2017-01-01

    This book offers a comprehensive, timely snapshot of current research, technologies and applications of soft robotics. The different chapters, written by international experts across multiple fields of soft robotics, cover innovative systems and technologies for soft robot legged locomotion, soft robot manipulation, underwater soft robotics, biomimetic soft robotic platforms, plant-inspired soft robots, flying soft robots, soft robotics in surgery, as well as methods for their modeling and control. Based on the results of the second edition of the Soft Robotics Week, held on April 25 – 30, 2016, in Livorno, Italy, the book reports on the major research lines and novel technologies presented and discussed during the event.

  11. Energy efficiency of mobile soft robots.

    Science.gov (United States)

    Shui, Langquan; Zhu, Liangliang; Yang, Zhe; Liu, Yilun; Chen, Xi

    2017-11-15

    The performance of mobile soft robots is usually characterized by their locomotion/velocity efficiency, whereas the energy efficiency is a more intrinsic and fundamental criterion for the performance evaluation of independent or integrated soft robots. In this work, a general framework is established to evaluate the energy efficiency of mobile soft robots by considering the efficiency of the energy source, actuator and locomotion, and some insights for improving the efficiency of soft robotic systems are presented. Proposed as the ratio of the desired locomotion kinetic energy to the input mechanical energy, the energy efficiency of locomotion is found to play a critical role in determining the overall energy efficiency of soft robots. Four key factors related to the locomotion energy efficiency are identified, that is, the locomotion modes, material properties, geometric sizes, and actuation states. It is found that the energy efficiency of most mobile soft robots reported in the literature is surprisingly low (mostly below 0.1%), due to the inefficient mechanical energy that essentially does not contribute to the desired locomotion. A comparison of the locomotion energy efficiency for several representative locomotion modes in the literature is presented, showing a descending ranking as: jumping ≫ fish-like swimming > snake-like slithering > rolling > rising/turning over > inchworm-like inching > quadruped gait > earthworm-like squirming. Besides, considering the same locomotion mode, soft robots with lower stiffness, higher density and larger size tend to have higher locomotion energy efficiency. Moreover, a periodic pulse actuation instead of a continuous actuation mode may significantly reduce the input mechanical energy, thus improving the locomotion energy efficiency, especially when the pulse actuation matches the resonant states of the soft robots. The results presented herein indicate a large and necessary space for improving the locomotion energy

  12. Rehabilitation robotics.

    Science.gov (United States)

    Krebs, H I; Volpe, B T

    2013-01-01

    This chapter focuses on rehabilitation robotics which can be used to augment the clinician's toolbox in order to deliver meaningful restorative therapy for an aging population, as well as on advances in orthotics to augment an individual's functional abilities beyond neurorestoration potential. The interest in rehabilitation robotics and orthotics is increasing steadily with marked growth in the last 10 years. This growth is understandable in view of the increased demand for caregivers and rehabilitation services escalating apace with the graying of the population. We provide an overview on improving function in people with a weak limb due to a neurological disorder who cannot properly control it to interact with the environment (orthotics); we then focus on tools to assist the clinician in promoting rehabilitation of an individual so that s/he can interact with the environment unassisted (rehabilitation robotics). We present a few clinical results occurring immediately poststroke as well as during the chronic phase that demonstrate superior gains for the upper extremity when employing rehabilitation robotics instead of usual care. These include the landmark VA-ROBOTICS multisite, randomized clinical study which demonstrates clinical gains for chronic stroke that go beyond usual care at no additional cost. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Medical robotics.

    Science.gov (United States)

    Ferrigno, Giancarlo; Baroni, Guido; Casolo, Federico; De Momi, Elena; Gini, Giuseppina; Matteucci, Matteo; Pedrocchi, Alessandra

    2011-01-01

    Information and communication technology (ICT) and mechatronics play a basic role in medical robotics and computer-aided therapy. In the last three decades, in fact, ICT technology has strongly entered the health-care field, bringing in new techniques to support therapy and rehabilitation. In this frame, medical robotics is an expansion of the service and professional robotics as well as other technologies, as surgical navigation has been introduced especially in minimally invasive surgery. Localization systems also provide treatments in radiotherapy and radiosurgery with high precision. Virtual or augmented reality plays a role for both surgical training and planning and for safe rehabilitation in the first stage of the recovery from neurological diseases. Also, in the chronic phase of motor diseases, robotics helps with special assistive devices and prostheses. Although, in the past, the actual need and advantage of navigation, localization, and robotics in surgery and therapy has been in doubt, today, the availability of better hardware (e.g., microrobots) and more sophisticated algorithms(e.g., machine learning and other cognitive approaches)has largely increased the field of applications of these technologies,making it more likely that, in the near future, their presence will be dramatically increased, taking advantage of the generational change of the end users and the increasing request of quality in health-care delivery and management.

  14. Understanding Friction Stir Welding

    Science.gov (United States)

    Nunes, A. C., Jr.

    2018-01-01

    This Technical Memorandum explains the friction stir welding process in terms of two basic concepts: the concentration of deformation in a shear surface enveloping the tool and the composition of the overall plastic flow field around the tool from simple flow field components. It is demonstrated how weld structure may be understood and torque, drag, and lateral tool forces may be estimated using these concepts. Some discrepancies between computations and accompanying empirical data are discussed in the text. This work is intended to be helpful to engineers in diagnosing problems and advancing technology.

  15. Friction in levitated superconductors

    International Nuclear Information System (INIS)

    Brandt, E.H.

    1988-01-01

    A type I superconductor levitated above a magnet of low symmetry has a unique equilibrium position about which it may oscillate freely. In contrast, a type II superconductor has a continuous range of stable equilibrium positions and orientations where it floats rigidly without swinging or orbiting as if it were stuck in sand. A strong internal friction conspicuously indicates the existence and unpinning of flux lines in oxide superconductors levitated above liquid nitrogen. It is shown how these effects follow from the hysteretic magnetization curves and how the energy is dissipated

  16. Robust Backstepping Control for Cold Rolling Main Drive System with Nonlinear Uncertainties

    Directory of Open Access Journals (Sweden)

    Xu Yang

    2013-01-01

    Full Text Available The nonlinear model of main drive system in cold rolling process, which considers the influence with parameter uncertainties such as clearance and variable friction coefficient, as well as external disturbance by roll eccentricity and variation of strip material quality, is built. By transformation, the lower triangular structure form of main drive system is obtained. The backstepping algorithm based on signal compensation is proposed to design a linear time-invariant (LTI robust controller, including a nominal controller and a robust compensator. A comparison with PI controller shows that the controller has better disturbance attenuation performance and tracking behaviors. Meanwhile, according to its LTI characteristic, the robust controller can be realized easily; therefore it is also appropriated to high speed dynamic rolling process.

  17. Generic robot architecture

    Science.gov (United States)

    Bruemmer, David J [Idaho Falls, ID; Few, Douglas A [Idaho Falls, ID

    2010-09-21

    The present invention provides methods, computer readable media, and apparatuses for a generic robot architecture providing a framework that is easily portable to a variety of robot platforms and is configured to provide hardware abstractions, abstractions for generic robot attributes, environment abstractions, and robot behaviors. The generic robot architecture includes a hardware abstraction level and a robot abstraction level. The hardware abstraction level is configured for developing hardware abstractions that define, monitor, and control hardware modules available on a robot platform. The robot abstraction level is configured for defining robot attributes and provides a software framework for building robot behaviors from the robot attributes. Each of the robot attributes includes hardware information from at least one hardware abstraction. In addition, each robot attribute is configured to substantially isolate the robot behaviors from the at least one hardware abstraction.

  18. Friction analysis of kinetic schemes : the friction coefficient

    NARCIS (Netherlands)

    Lolkema, Juke S.

    1995-01-01

    Friction analysis is proposed as the application of general control analysis to single enzymes to describe the control of elementary kinetic steps on the overall catalytic rate. For each transition, a friction coefficient is defined that measures the sensitivity of the turnover rate to the free

  19. Frictional behaviour of high performance fibrous tows: Friction experiments

    NARCIS (Netherlands)

    Cornelissen, Bo; Rietman, Bert; Akkerman, Remko

    2013-01-01

    Tow friction is an important mechanism in the production and processing of high performance fibrous tows. The frictional behaviour of these tows is anisotropic due to the texture of the filaments as well as the tows. This work describes capstan experiments that were performed to measure the

  20. 'Filigree Robotics'

    DEFF Research Database (Denmark)

    2016-01-01

    -scale 3D printed ceramics accompanied by prints, videos and ceramic probes, which introduce the material and design processes of the project.'Filigree Robotics' experiments with a combination of the traditional ceramic technique of ‘Overforming’ with 3d Laserscan and Robotic extrusion technique...... application of reflectivity after an initial 3d print. The consideration and integration of this material practice into a digital workflow took place in an interdisciplinary collaboration of Ceramicist Flemming Tvede Hansen from KADK Superformlab and architectural researchers from CITA (Martin Tamke, Henrik...... to the creation of the form and invites for experimentation. In Filigree Robotics we combine the crafting of the mold with a parallel running generative algorithm, which is fed by a constant laserscan of the 3d surface. This algorithm, analyses the topology of the mold, identifies high and low points and uses...

  1. Cloud Robotics Platforms

    Directory of Open Access Journals (Sweden)

    Busra Koken

    2015-01-01

    Full Text Available Cloud robotics is a rapidly evolving field that allows robots to offload computation-intensive and storage-intensive jobs into the cloud. Robots are limited in terms of computational capacity, memory and storage. Cloud provides unlimited computation power, memory, storage and especially collaboration opportunity. Cloud-enabled robots are divided into two categories as standalone and networked robots. This article surveys cloud robotic platforms, standalone and networked robotic works such as grasping, simultaneous localization and mapping (SLAM and monitoring.

  2. Hot rolling of thick uranium molybdenum alloys

    Science.gov (United States)

    DeMint, Amy L.; Gooch, Jack G.

    2015-11-17

    Disclosed herein are processes for hot rolling billets of uranium that have been alloyed with about ten weight percent molybdenum to produce cold-rollable sheets that are about one hundred mils thick. In certain embodiments, the billets have a thickness of about 7/8 inch or greater. Disclosed processes typically involve a rolling schedule that includes a light rolling pass and at least one medium rolling pass. Processes may also include reheating the rolling stock and using one or more heavy rolling passes, and may include an annealing step.

  3. Lateral position detection and control for friction stir systems

    Science.gov (United States)

    Fleming, Paul; Lammlein, David; Cook, George E.; Wilkes, Don Mitchell; Strauss, Alvin M.; Delapp, David; Hartman, Daniel A.

    2010-12-14

    A friction stir system for processing at least a first workpiece includes a spindle actuator coupled to a rotary tool comprising a rotating member for contacting and processing the first workpiece. A detection system is provided for obtaining information related to a lateral alignment of the rotating member. The detection system comprises at least one sensor for measuring a force experienced by the rotary tool or a parameter related to the force experienced by the rotary tool during processing, wherein the sensor provides sensor signals. A signal processing system is coupled to receive and analyze the sensor signals and determine a lateral alignment of the rotating member relative to a selected lateral position, a selected path, or a direction to decrease a lateral distance relative to the selected lateral position or selected path. In one embodiment, the friction stir system can be embodied as a closed loop tracking system, such as a robot-based tracked friction stir welding (FSW) or friction stir processing (FSP) system.

  4. Medical robotics

    CERN Document Server

    Troccaz, Jocelyne

    2013-01-01

    In this book, we present medical robotics, its evolution over the last 30 years in terms of architecture, design and control, and the main scientific and clinical contributions to the field. For more than two decades, robots have been part of hospitals and have progressively become a common tool for the clinician. Because this domain has now reached a certain level of maturity it seems important and useful to provide a state of the scientific, technological and clinical achievements and still open issues. This book describes the short history of the domain, its specificity and constraints, and

  5. Service Robots

    DEFF Research Database (Denmark)

    Clemmensen, Torkil; Nielsen, Jeppe Agger; Andersen, Kim Normann

    The position presented in this paper is that in order to understand how service robots shape, and are being shaped by, the physical and social contexts in which they are used, we need to consider both work/organizational analysis and interaction design. We illustrate this with qualitative data...... and personal experiences to generate discussion about how to link these two traditions. This paper presents selected results from a case study that investigated the implementation and use of robot vacuum cleaners in Danish eldercare. The study demonstrates interpretive flexibility with variation...

  6. Robot Choreography

    DEFF Research Database (Denmark)

    Jochum, Elizabeth Ann; Heath, Damith

    2016-01-01

    We propose a robust framework for combining performance paradigms with human robot interaction (HRI) research. Following an analysis of several case studies that combine the performing arts with HRI experiments, we propose a methodology and “best practices” for implementing choreography and other...... performance paradigms in HRI experiments. Case studies include experiments conducted in laboratory settings, “in the wild”, and live performance settings. We consider the technical and artistic challenges of designing and staging robots alongside humans in these various settings, and discuss how to combine...

  7. Internal friction, microstructure, and radiation effects

    International Nuclear Information System (INIS)

    Wechsler, M.S.; Sommer, W.F.; Davidson, D.R.

    1984-01-01

    A brief review is given of internal friction relaxation peaks and background internal friction. The microstructural origin of the internal friction is discussed. Particular emphasis is placed on radiation effects

  8. Robust Rudder Roll Damping Control

    DEFF Research Database (Denmark)

    Yang, C.

    The results of a systematic research to solve a specific ship motion control problem, simultaneous roll damping and course keeping using the rudder are presented in this thesis. The fundamental knowledge a priori is that rudder roll damping is highly sensitive to the model uncertainty, therefore H-infinity...... theory is used to deal with the problem. The necessary mathematical tools and the H-Infinity theory as the basis of controller design are presented in Chapter 2 and 3. The mu synthesis and the D-K iteration are introduced in Chapter 3. The ship dynamics and modeling technology are discussed in Chapter 4...

  9. Friction Stir Welding

    Science.gov (United States)

    Nunes, Arthur C., Jr.

    2008-01-01

    Friction stir welding (FSW) is a solid state welding process invented in 1991 at The Welding Institute in the United Kingdom. A weld is made in the FSW process by translating a rotating pin along a weld seam so as to stir the sides of the seam together. FSW avoids deleterious effects inherent in melting and promises to be an important welding process for any industries where welds of optimal quality are demanded. This article provides an introduction to the FSW process. The chief concern is the physical effect of the tool on the weld metal: how weld seam bonding takes place, what kind of weld structure is generated, potential problems, possible defects for example, and implications for process parameters and tool design. Weld properties are determined by structure, and the structure of friction stir welds is determined by the weld metal flow field in the vicinity of the weld tool. Metal flow in the vicinity of the weld tool is explained through a simple kinematic flow model that decomposes the flow field into three basic component flows: a uniform translation, a rotating solid cylinder, and a ring vortex encircling the tool. The flow components, superposed to construct the flow model, can be related to particular aspects of weld process parameters and tool design; they provide a bridge to an understanding of a complex-at-first-glance weld structure. Torques and forces are also discussed. Some simple mathematical models of structural aspects, torques, and forces are included.

  10. Cultural Robotics: The Culture of Robotics and Robotics in Culture

    Directory of Open Access Journals (Sweden)

    Hooman Samani

    2013-12-01

    Full Text Available In this paper, we have investigated the concept of “Cultural Robotics” with regard to the evolution of social into cultural robots in the 21st Century. By defining the concept of culture, the potential development of a culture between humans and robots is explored. Based on the cultural values of the robotics developers, and the learning ability of current robots, cultural attributes in this regard are in the process of being formed, which would define the new concept of cultural robotics. According to the importance of the embodiment of robots in the sense of presence, the influence of robots in communication culture is anticipated. The sustainability of robotics culture based on diversity for cultural communities for various acceptance modalities is explored in order to anticipate the creation of different attributes of culture between robots and humans in the future.

  11. Design of a variable-stiffness robotic hand using pneumatic soft rubber actuators

    International Nuclear Information System (INIS)

    Nagase, Jun-ya; Saga, Norihiko; Wakimoto, Shuichi; Satoh, Toshiyuki; Suzumori, Koichi

    2011-01-01

    In recent years, Japanese society has been ageing, engendering a labor shortage of young workers. Robots are therefore expected to be useful in performing tasks such as day-to-day support for elderly people. In particular, robots that are intended for use in the field of medical care and welfare are expected to be safe when operating in a human environment because they often come into contact with people. Furthermore, robots must perform various tasks such as regrasping, grasping of soft objects, and tasks using frictional force. Given these demands and circumstances, a tendon-driven robot hand with a stiffness changing finger has been developed. The finger surface stiffness can be altered by adjusting the input pressure depending on the task. Additionally, the coefficient of static friction can be altered by changing the surface stiffness merely by adjusting the input air pressure. This report describes the basic structure, driving mechanism, and basic properties of the proposed robot hand

  12. Robot vision for nuclear advanced robot

    International Nuclear Information System (INIS)

    Nakayama, Ryoichi; Okano, Hideharu; Kuno, Yoshinori; Miyazawa, Tatsuo; Shimada, Hideo; Okada, Satoshi; Kawamura, Astuo

    1991-01-01

    This paper describes Robot Vision and Operation System for Nuclear Advanced Robot. This Robot Vision consists of robot position detection, obstacle detection and object recognition. With these vision techniques, a mobile robot can make a path and move autonomously along the planned path. The authors implemented the above robot vision system on the 'Advanced Robot for Nuclear Power Plant' and tested in an environment mocked up as nuclear power plant facilities. Since the operation system for this robot consists of operator's console and a large stereo monitor, this system can be easily operated by one person. Experimental tests were made using the Advanced Robot (nuclear robot). Results indicate that the proposed operation system is very useful, and can be operate by only person. (author)

  13. Blades Couple Dry Friction Connection

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk; Radolfová, Alena

    2015-01-01

    Roč. 9, č. 1 (2015), s. 31-40 ISSN 1802-680X Institutional support: RVO:61388998 Keywords : stick-slip dry friction * 3D friction characteristic * tangential contact stiffness * hysterezis loop * response curves Subject RIV: BI - Acoustics

  14. Friction laws at the nanoscale.

    Science.gov (United States)

    Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

    2009-02-26

    Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

  15. Corrosion effects on friction factors

    International Nuclear Information System (INIS)

    Magleby, H.L.; Shaffer, S.J.

    1996-01-01

    This paper presents the results of NRC-sponsored material specimen tests that were performed to determine if corrosion increases the friction factors of sliding surfaces of motor-operated gate valves, which could require higher forces to close and open safety-related valves when subjected to their design basis differential pressures. Friction tests were performed with uncorroded specimens and specimens subjected to accelerated corrosion. Preliminary tests at ambient conditions showed that corrosion increased the friction factors, indicating the need for additional tests duplicating valve operating parameters at hot conditions. The additional tests showed friction factors of corroded specimens were 0.1 to 0.2 higher than for uncorroded specimens, and that the friction factors of the corroded specimens were not very dependent on contact stress or corrosion film thickness. The measured values of friction factors for the three corrosion films tested (simulating three operating times) were in the range of 0.3 to 0.4. The friction factor for even the shortest simulated operating time was essentially the same as the others, indicating that the friction factors appear to reach a plateau and that the plateau is reached quickly

  16. Robot-Aided Neurorehabilitation: A Pediatric Robot for Ankle Rehabilitation.

    Science.gov (United States)

    Michmizos, Konstantinos P; Rossi, Stefano; Castelli, Enrico; Cappa, Paolo; Krebs, Hermano Igo

    2015-11-01

    This paper presents the pediAnklebot, an impedance-controlled low-friction, backdriveable robotic device developed at the Massachusetts Institute of Technology that trains the ankle of neurologically impaired children of ages 6-10 years old. The design attempts to overcome the known limitations of the lower extremity robotics and the unknown difficulties of what constitutes an appropriate therapeutic interaction with children. The robot's pilot clinical evaluation is on-going and it incorporates our recent findings on the ankle sensorimotor control in neurologically intact subjects, namely the speed-accuracy tradeoff, the deviation from an ideally smooth ankle trajectory, and the reaction time. We used these concepts to develop the kinematic and kinetic performance metrics that guided the ankle therapy in a similar fashion that we have done for our upper extremity devices. Here we report on the use of the device in at least nine training sessions for three neurologically impaired children. Results demonstrated a statistically significant improvement in the performance metrics assessing explicit and implicit motor learning. Based on these initial results, we are confident that the device will become an effective tool that harnesses plasticity to guide habilitation during childhood.

  17. The effect of roll with passive segment on the planetary rolling process

    Directory of Open Access Journals (Sweden)

    Qing-Ling Zeng

    2015-03-01

    Full Text Available In three-roll planetary rolling process, there is secondary torsion phenomenon that may lead to rolling instability. This article proposed a new idea to alleviate the secondary torsion phenomenon by dividing the secondary torsion segment out of the roll as an independent and passive one. To study the performance of the roll with passive segment, the three-dimensional finite element models of planetary rolling process using actual roll or new roll with passive segment involving elastic–plastic and thermal–mechanical coupling were established by the software ABAQUS/Explicit, and a series of analysis had been done successfully. The rolling temperature and rolling force of planetary mill were in good agreement with the measured results, which indicated that the finite element method would supply important reference merit for three-dimensional thermo-mechanical simulation of the three-roll planetary rolling process. Comparing the simulation results of the two models, the results indicated that the change in the roll structure had just a little influence on the metal deformation, temperature, and rolling force, but it lessened the secondary torsion deformation effectively and improved the outside roundness of the rolled tube slightly. The research provided a new idea for the roll design of three-roll planetary mill (PSW.

  18. Robotic Surgery

    Science.gov (United States)

    Childress, Vincent W.

    2007-01-01

    The medical field has many uses for automated and remote-controlled technology. For example, if a tissue sample is only handled in the laboratory by a robotic handling system, then it will never come into contact with a human. Such a system not only helps to automate the medical testing process, but it also helps to reduce the chances of…

  19. Elastomers in Combined Rolling-Sliding Contact; Wear and its Underlying Mechanisms

    Science.gov (United States)

    Rowe, Kyle Gene

    Elastomeric materials, specifically rubbers, being both of a practical and scientific importance, have been the subjects of vast amounts of research spanning well over two centuries. There is currently a large effort by tire manufacturers to design new rubber compounds with lower rolling resistance, higher sliding friction, and reduced or predictable wear. At present, these efforts are primarily based on a few empirical rules and very costly trial and error testing; only a basic understanding of the mechanisms involved in the wear of elastomeric materials exists despite rigorous study. In general, the only well controlled experiments have been for simple loading and sliding schemes. The aim of this work is to characterize the tribological properties of a carbon black filled natural rubber sample. This work explores (1) its behavior in unidirectional sliding, (2) contact mechanics, (3) traction properties in combined rolling and sliding, (4) frictional heating response, and (5) wear. It was found that the friction coefficient of this material was dependent upon sliding velocity, contact pressure, and surface roughness. The high friction coefficients also lead to a bifurcation of the contact area into two different pressure regimes at sliding velocities greater than 10 mm/s . The traction response of this material in combined rolling and sliding exhibited similar behavior, being a function of the contact pressure, but not rolling velocity. The wear of this material was found to be linearly dependent upon the global slip condition and occurred preferentially on the sample. Investigations of the worn surface revealed that the most likely mechanism of wear is the degradation of surface material in a confined layer a few micrometers thick. A simple spring-mass model was developed to offer an explanation of localized wear. It was found that the coupling of system elements in the normal direction helped to shift the load from wearing elements to non-wearing ones. The

  20. Tactile friction of topical formulations.

    Science.gov (United States)

    Skedung, L; Buraczewska-Norin, I; Dawood, N; Rutland, M W; Ringstad, L

    2016-02-01

    The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Laws on Robots, Laws by Robots, Laws in Robots : Regulating Robot Behaviour by Design

    NARCIS (Netherlands)

    Leenes, R.E.; Lucivero, F.

    2015-01-01

    Speculation about robot morality is almost as old as the concept of a robot itself. Asimov’s three laws of robotics provide an early and well-discussed example of moral rules robots should observe. Despite the widespread influence of the three laws of robotics and their role in shaping visions of

  2. Rolling motion in moving droplets

    Indian Academy of Sciences (India)

    motions. The two limits of a thin sheet-like drop in sliding motion on a surface, and a spherical drop in roll, have been extensively .... rigid body rotation. The solid body rotation makes sense in the context of small Reynolds. (Re) number flows ...

  3. The sound of friction: Real-time models, playability and musical applications

    Science.gov (United States)

    Serafin, Stefania

    Friction, the tangential force between objects in contact, in most engineering applications needs to be removed as a source of noise and instabilities. In musical applications, friction is a desirable component, being the sound production mechanism of different musical instruments such as bowed strings, musical saws, rubbed bowls and any other sonority produced by interactions between rubbed dry surfaces. The goal of the dissertation is to simulate different instrument whose main excitation mechanism is friction. An efficient yet accurate model of a bowed string instrument, which combines the latest results in violin acoustics with the efficient digital waveguide approach, is provided. In particular, the bowed string physical model proposed uses a thermodynamic friction model in which the finite width of the bow is taken into account; this solution is compared to the recently developed elasto-plastic friction models used in haptics and robotics. Different solutions are also proposed to model the body of the instrument. Other less common instruments driven by friction are also proposed, and the elasto-plastic model is used to provide audio-visual simulations of everyday friction sounds such as squeaking doors and rubbed wine glasses. Finally, playability evaluations and musical applications in which the models have been used are discussed.

  4. Frictional Heating with Time-Dependent Specific Power of Friction

    Directory of Open Access Journals (Sweden)

    Topczewska Katarzyna

    2017-06-01

    Full Text Available In this paper analytical solutions of the thermal problems of friction were received. The appropriate boundary-value problems of heat conduction were formulated and solved for a homogeneous semi–space (a brake disc heated on its free surface by frictional heat fluxes with different and time-dependent intensities. Solutions were obtained in dimensionless form using Duhamel's theorem. Based on received solutions, evolution and spatial distribution of the dimensionless temperature were analyzed using numerical methods. The numerical results allowed to determine influence of the time distribution of friction power on the spatio-temporal temperature distribution in brake disc.

  5. Wave friction factor rediscovered

    Science.gov (United States)

    Le Roux, J. P.

    2012-02-01

    The wave friction factor is commonly expressed as a function of the horizontal water particle semi-excursion ( A wb) at the top of the boundary layer. A wb, in turn, is normally derived from linear wave theory by {{U_{{wb}}/T_{{w}}}}{{2π }} , where U wb is the maximum water particle velocity measured at the top of the boundary layer and T w is the wave period. However, it is shown here that A wb determined in this way deviates drastically from its real value under both linear and non-linear waves. Three equations for smooth, transitional and rough boundary conditions, respectively, are proposed to solve this problem, all three being a function of U wb, T w, and δ, the thickness of the boundary layer. Because these variables can be determined theoretically for any bottom slope and water depth using the deepwater wave conditions, there is no need to physically measure them. Although differing substantially from many modern attempts to define the wave friction factor, the results coincide with equations proposed in the 1960s for either smooth or rough boundary conditions. The findings also confirm that the long-held notion of circular water particle motion down to the bottom in deepwater conditions is erroneous, the motion in fact being circular at the surface and elliptical at depth in both deep and shallow water conditions, with only horizontal motion at the top of the boundary layer. The new equations are incorporated in an updated version (WAVECALC II) of the Excel program published earlier in this journal by Le Roux et al. Geo-Mar Lett 30(5): 549-560, (2010).

  6. Maintenance Appointments in Railway Rolling Stock Rescheduling

    NARCIS (Netherlands)

    J.C. Wagenaar (Joris); L.G. Kroon (Leo); M.E. Schmidt (Marie)

    2016-01-01

    textabstractThis paper addresses the Rolling Stock Rescheduling Problem (RSRP), while taking maintenance appointments into account. After a disruption, the rolling stock of the disrupted passenger trains has to be rescheduled in order to restore a feasible rolling stock circulation. Usually, a

  7. Rolling block mazes are PSPACE-complete

    NARCIS (Netherlands)

    Buchin, K.; Buchin, M.

    2012-01-01

    In a rolling block maze, one or more blocks lie on a rectangular board with square cells. In most mazes, the blocks have size k × m × n where k, m, n are integers that determine the size of the block in terms of units of the size of the board cells. The task of a rolling block maze is to roll a

  8. Efficient Circulation of Railway Rolling Stock

    NARCIS (Netherlands)

    Alfieri, A.; Groot, R.; Kroon, L.G.; Schrijver, A.

    2006-01-01

    Railway rolling stock (locomotives, carriages, and train units) is one of the most significant cost sources for operatorsof passenger trains, both public and private. Rolling stock costsare due to material acquisition, power supply, and material maintenance. The efficient circulation of rolling

  9. Friction and anchorage loading revisited.

    Science.gov (United States)

    Dholakia, Kartik D

    2012-01-01

    Contemporary concepts of sliding mechanics explain that friction is inevitable. To overcome this frictional resistance, excess force is required to retract the tooth along the archwire (ie, individual retraction of canines, en masse retraction of anterior teeth), in addition to the amount of force required for tooth movement. The anterior tooth retraction force, in addition to excess force (to overcome friction), produces reciprocal protraction force on molars, thereby leading to increased anchorage loading. However, this traditional concept was challenged in recent literature, which was based on the finite element model, but did not bear correlation to the clinical scenario. This article will reinforce the fact that clinically, friction increases anchorage loading in all three planes of space, considering the fact that tooth movement is a quasistatic process rather than a purely continuous or static one, and that conventional ways of determining the effects of static or dynamic friction on anchorage load cannot be applied to clinical situations (which consist of anatomical resistance units and a complex muscular force system). The article does not aim to quantify friction and its effect on the amount of anchorage load. Rather, a new perspective regarding the role of various additional factors (which is not explained by contemporary concept) that may influence friction and anchorage loading is provided..

  10. Micro Robotics Lab

    Data.gov (United States)

    Federal Laboratory Consortium — Our research is focused on the challenges of engineering robotic systems down to sub-millimeter size scales. We work both on small mobile robots (robotic insects for...

  11. Robots of the Future

    Indian Academy of Sciences (India)

    two main types of robots: industrial robots, and autonomous robots. .... position); it also has a virtual CPU with two stacks and three registers that hold 32-bit strings. Each item ..... just like we can aggregate images, text, and information from.

  12. Presentation robot Advee

    Czech Academy of Sciences Publication Activity Database

    Krejsa, Jiří; Věchet, Stanislav; Hrbáček, J.; Ripel, T.; Ondroušek, V.; Hrbáček, R.; Schreiber, P.

    2012-01-01

    Roč. 18, 5/6 (2012), s. 307-322 ISSN 1802-1484 Institutional research plan: CEZ:AV0Z20760514 Keywords : mobile robot * human - robot interface * localization Subject RIV: JD - Computer Applications, Robot ics

  13. Towards Sociable Robots

    DEFF Research Database (Denmark)

    Ngo, Trung Dung

    This thesis studies aspects of self-sufficient energy (energy autonomy) for truly autonomous robots and towards sociable robots. Over sixty years of history of robotics through three developmental ages containing single robot, multi-robot systems, and social (sociable) robots, the main objective...... of roboticists mostly focuses on how to make a robotic system function autonomously and further, socially. However, such approaches mostly emphasize behavioural autonomy, rather than energy autonomy which is the key factor for not only any living machine, but for life on the earth. Consequently, self......-sufficient energy is one of the challenges for not only single robot or multi-robot systems, but also social and sociable robots. This thesis is to deal with energy autonomy for multi-robot systems through energy sharing (trophallaxis) in which each robot is equipped with two capabilities: self-refueling energy...

  14. Towards roll-to-roll manufacturing of polymer photonic devices

    Science.gov (United States)

    Subbaraman, Harish; Lin, Xiaohui; Ling, Tao; Guo, L. Jay; Chen, Ray T.

    2014-03-01

    Traditionally, polymer photonic devices are fabricated using clean-room processes such as photolithography, e-beam lithography, reactive ion etching (RIE) and lift-off methods etc, which leads to long fabrication time, low throughput and high cost. We have utilized a novel process for fabricating polymer photonic devices using a combination of imprinting and ink jet printing methods, which provides high throughput on a variety of rigid and flexible substrates with low cost. We discuss the manufacturing challenges that need to be overcome in order to realize true implementation of roll-to-roll manufacturing of flexible polymer photonic systems. Several metrology and instrumentation challenges involved such as availability of particulate-free high quality substrate, development and implementation of high-speed in-line and off-line inspection and diagnostic tools with adaptive control for patterned and unpatterned material films, development of reliable hardware, etc need to be addressed and overcome in order to realize a successful manufacturing process. Due to extreme resolution requirements compared to print media, the burden of software and hardware tools on the throughput also needs to be carefully determined. Moreover, the effect of web wander and variations in web speed need to accurately be determined in the design of the system hardware and software. In this paper, we show the realization of solutions for few challenges, and utilizing these solutions for developing a high-rate R2R dual stage ink-jet printer that can provide alignment accuracy of web speed of 5m/min. The development of a roll-to-roll manufacturing system for polymer photonic systems opens limitless possibilities for the deployment of high performance components in a variety of applications including communication, sensing, medicine, agriculture, energy, lighting etc.

  15. Perovskite solar cells for roll-to-roll fabrication

    Directory of Open Access Journals (Sweden)

    Uddin Ashraf

    2017-01-01

    Full Text Available Perovskite solar cell (PSCs is considered as the game changer in emerging photovoltaics technology. The highest certified efficiency is 22% with high temperature processed (∼500 °C TiO2 based electron transport layer (ETL. High temperature process is a rudimentary hindrance towards roll-to-roll processing of PSCs on flexible substrates. Low temperature solution process (<150 °C ZnO based ETL is one of the most promising candidate for large scale roll-to-roll fabrication of cells as it has nearly identical electron affinity (4.2 eV of TiO2. The mixed organic perovskite (MA0.6FA0.4PbI3 devices with Al doped ZnO (AZO ETL demonstrate average cell efficiency over 16%, which is the highest ever reported efficiency for this device configuration. The energy level alignment and related interfacial charge transport dynamics at the interface of ZnO and perovskite films and the adjacent charge transport layers are investigated. Significantly improved device stability, hysteresis free device photocurrent have been observed in MA0.6FA0.4PbI3 cells. A systematic electrochemical impedance spectroscopy, frequency dependent capacitance spectra, surface morphology and topography characterization have been conducted to understand the role of interfacial electronic properties between perovskite and neighbouring layers in perovskite device. A standardized degradation study, interfacial electronic property and capacitive spectra analysis of aged device, have been measured to understand the enhanced device stability in mixed MA0.6FA0.4PbI3 cells. Slow perovskite material decomposition rate and augmented device lifetime with AZO based devices have been found to be correlated with the more hydrophobic and acidic nature of AZO surface compared to pristine ZnO film.

  16. Flow Friction or Spontaneous Ignition?

    Science.gov (United States)

    Stoltzfus, Joel M.; Gallus, Timothy D.; Sparks, Kyle

    2012-01-01

    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system.

  17. [Friction: self-ligating brackets].

    Science.gov (United States)

    Thermac, Guilhem; Morgon, Laurent; Godeneche, Julien

    2008-12-01

    The manufacturers of self-ligating brackets advertise a reduction of the friction engendered between the wire and the bracket, which is an essential parameter for treatment's speed and comfort. We have compared the friction obtained with four types of self-ligating brackets - In-Ovation R, Damon 3, Smart Clip and Quick - with that of a standard bracket Omniarch associated with an elastomeric ligature. All bracket were tested on a bench of traction with three types of wires: steel .019"x.025", TMA .019"x.025" and NEO sentalloy F300 .020"x.020". The results confirm a clear friction reduction for all tested wire.

  18. Review on Parameters Influencing the Rice Breakage and Rubber Roll Wear in Sheller

    Directory of Open Access Journals (Sweden)

    Prabhakaran P.

    2017-09-01

    Full Text Available The present review deals with parameters influencing the rice breakage during rice milling operations and the effect of rubber roll Sheller in rice husk removal process. The main objective of rice milling system is to remove the husk and bran layer to produce the white rice. In this process, rubber roll sheller is used to remove husk from the grains by friction process. If the rubber material is too soft, there may not be sufficient shear force to husk the paddy. Wear will be minimum for rubber material with high hardness but indeed it pronounce the breakage of rice. Hence, for efficient husking the rubber roll material should possess the balance of physico-mechanical properties. Rice breakage depends on several other parameters like the type of harvest, drying temperature, drying methods, physical characteristics of paddy, husking characteristics, paddy moisture content, rubber roller speed, rubber roll pressure, paddy feed rate and fissures. Rubber roll wear depends on the type of rubber material attached to the roller, feed rate, roller speed, pressure etc.

  19. Cloud Robotics Model

    OpenAIRE

    Mester, Gyula

    2015-01-01

    Cloud Robotics was born from the merger of service robotics and cloud technologies. It allows robots to benefit from the powerful computational, storage, and communications resources of modern data centres. Cloud robotics allows robots to take advantage of the rapid increase in data transfer rates to offload tasks without hard real time requirements. Cloud Robotics has rapidly gained momentum with initiatives by companies such as Google, Willow Garage and Gostai as well as more than a dozen a...

  20. On the constant-roll inflation

    Science.gov (United States)

    Yi, Zhu; Gong, Yungui

    2018-03-01

    The primordial power spectra of scalar and tensor perturbations during slow-roll inflation are usually calculated with the method of Bessel function approximation. For constant-roll or ultra slow-roll inflation, the method of Bessel function approximation may be invalid. We compare the numerical results with the analytical results derived from the Bessel function approximation, and we find that they differ significantly on super-horizon scales if the constant slow-roll parameter ηH is not small. More accurate method is needed for calculating the primordial power spectrum for constant-roll inflation.

  1. Robot Programming.

    Science.gov (United States)

    1982-12-01

    Paris, France, June, 1982, 519-530. Latoinbe, J. C. "Equipe Intelligence Artificielle et Robotique: Etat d’avancement des recherches," Laboratoire...8217AD-A127 233 ROBOT PROGRRMMING(U) MASSACHUSETTS INST OFGTECHi/ CAMBRIDGE ARTIFICIAL INTELLIGENCE LAB T LOZANO-PEREZ UNCLASSIFIED DC8 AI-9 N884...NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK Artificial Intelligence Laboratory AREA I WORK UNIT NUMBERS ,. 545 Technology Square Cambridge

  2. Showing Area Matters: A Work of Friction

    Science.gov (United States)

    Van Domelen, David

    2010-01-01

    Typically, we teach the simplified friction equation of the form F[subscript s] = [mu][subscript s]N for static friction, where F[subscript s] is the maximum static friction, [mu][subscript s] is the coefficient of static friction, and "N" is the normal force pressing the surfaces together. However, this is a bit too simplified, and…

  3. A Pedagogical Model of Static Friction

    OpenAIRE

    Pickett, Galen T.

    2015-01-01

    While dry Coulombic friction is an elementary topic in any standard introductory course in mechanics, the critical distinction between the kinetic and static friction forces is something that is both hard to teach and to learn. In this paper, I describe a geometric model of static friction that may help introductory students to both understand and apply the Coulomb static friction approximation.

  4. Multimodal Friction Ignition Tester

    Science.gov (United States)

    Davis, Eddie; Howard, Bill; Herald, Stephen

    2009-01-01

    The multimodal friction ignition tester (MFIT) is a testbed for experiments on the thermal and mechanical effects of friction on material specimens in pressurized, oxygen-rich atmospheres. In simplest terms, a test involves recording sensory data while rubbing two specimens against each other at a controlled normal force, with either a random stroke or a sinusoidal stroke having controlled amplitude and frequency. The term multimodal in the full name of the apparatus refers to a capability for imposing any combination of widely ranging values of the atmospheric pressure, atmospheric oxygen content, stroke length, stroke frequency, and normal force. The MFIT was designed especially for studying the tendency toward heating and combustion of nonmetallic composite materials and the fretting of metals subjected to dynamic (vibrational) friction forces in the presence of liquid oxygen or pressurized gaseous oxygen test conditions approximating conditions expected to be encountered in proposed composite material oxygen tanks aboard aircraft and spacecraft in flight. The MFIT includes a stainless-steel pressure vessel capable of retaining the required test atmosphere. Mounted atop the vessel is a pneumatic cylinder containing a piston for exerting the specified normal force between the two specimens. Through a shaft seal, the piston shaft extends downward into the vessel. One of the specimens is mounted on a block, denoted the pressure block, at the lower end of the piston shaft. This specimen is pressed down against the other specimen, which is mounted in a recess in another block, denoted the slip block, that can be moved horizontally but not vertically. The slip block is driven in reciprocating horizontal motion by an electrodynamic vibration exciter outside the pressure vessel. The armature of the electrodynamic exciter is connected to the slip block via a horizontal shaft that extends into the pressure vessel via a second shaft seal. The reciprocating horizontal

  5. Friction induced hunting limit cycles : a comparison between the LuGre and switch friction model

    NARCIS (Netherlands)

    Hensen, R.H.A.; Molengraft, van de M.J.G.; Steinbuch, M.

    2003-01-01

    In this paper, friction induced limit cycles are predicted for a simple motion system consisting of a motor-driven inertia subjected to friction and a PID-controlled regulator task. The two friction models used, i.e., (i) the dynamic LuGre friction model and (ii) the static switch friction model,

  6. Friendly network robotics; Friendly network robotics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    This paper summarizes the research results on the friendly network robotics in fiscal 1996. This research assumes an android robot as an ultimate robot and the future robot system utilizing computer network technology. The robot aiming at human daily work activities in factories or under extreme environments is required to work under usual human work environments. The human robot with similar size, shape and functions to human being is desirable. Such robot having a head with two eyes, two ears and mouth can hold a conversation with human being, can walk with two legs by autonomous adaptive control, and has a behavior intelligence. Remote operation of such robot is also possible through high-speed computer network. As a key technology to use this robot under coexistence with human being, establishment of human coexistent robotics was studied. As network based robotics, use of robots connected with computer networks was also studied. In addition, the R-cube (R{sup 3}) plan (realtime remote control robot technology) was proposed. 82 refs., 86 figs., 12 tabs.

  7. Improved Dutch Roll Approximation for Hypersonic Vehicle

    Directory of Open Access Journals (Sweden)

    Liang-Liang Yin

    2014-06-01

    Full Text Available An improved dutch roll approximation for hypersonic vehicle is presented. From the new approximations, the dutch roll frequency is shown to be a function of the stability axis yaw stability and the dutch roll damping is mainly effected by the roll damping ratio. In additional, an important parameter called roll-to-yaw ratio is obtained to describe the dutch roll mode. Solution shows that large-roll-to-yaw ratio is the generate character of hypersonic vehicle, which results the large error for the practical approximation. Predictions from the literal approximations derived in this paper are compared with actual numerical values for s example hypersonic vehicle, results show the approximations work well and the error is below 10 %.

  8. Evaluation of dose delivery accuracy due to variation in pitch and roll

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Chang Young; Bae, Sun Myung; Lee, Dong Hyung; Min, Soon Ki; Kang, Tae Young; Baek, Geum Mun [Dept. of Radiation Oncology, ASAN Medical Center, Seoul (Korea, Republic of)

    2014-12-15

    The purpose of this study is to verify the accuracy of dose delivery according to the pitch and roll rotational setup error with 6D robotic couch in Intensity Modulated Radiation Therapy ( IMRT ) for pelvic region in patients. Trilogy(Varian, USA) and 6D robotic couch(ProturaTM 1.4, CIVCO, USA) were used to measure and analyze the rotational setup error of 14 patients (157 setup cases) for pelvic region. The total 157 Images(CBCT 78, Radiography 79) were used to calculate the mean value and the incidence of pitch and roll rotational setup error with Microsoft Office Excel 2007. The measured data (3 mm, 3%) at the reference angle (0 °) without couch rotation of pitch and roll direction was compared to the others at different pitch and roll angles (1 °, 1.5 °, 2 °, 2.5 °) to verify the accuracy of dose delivery by using 2D array ionization chamber (I'mRT Matrixx, IBA Dosimetry, Germany) and MultiCube Phantom(IBA Dosimetry, Germany). Result from the data, gamma index was evaluated. The mean values of pitch and roll rotational setup error were 0.9±0.7 °, 0.5±0.6 °. The maximum values of them were 2.8 °, 2.0 °. All of the minimum values were zero. The mean values of gamma pass rate at four different pitch angles (1 °, 1.5 °, 2 °, 2.5 °) were 97.75%, 96.65%, 94.38% and 90.91%. The mean values of gamma pass rate at four different roll angles (1 °, 1.5 °, 2 °, 2.5 °) were 93.68%, 93.05%, 87.77% and 84.96%. when the same angles (1 °, 1.5 °, 2 ° ) of pitch and roll were applied simultaneously, The mean values of each angle were 94.90%, 92.37% and 87.88%, respectively. As a result of this study, it was able to recognize that the accuracy of dose delivered is lowered gradually as pitch and roll increases. In order to increase the accuracy of delivered dose, therefore, it is recommended to perform IGRT or correct patient's position in the pitch and roll direction, to improve the quality of treatment.

  9. Effect of Polypropylene Modification by Impregnation with Oil on Its Wear and Friction Coefficient at Variable Load and Various Friction Rates

    Directory of Open Access Journals (Sweden)

    Paweł Sędłak

    2017-01-01

    Full Text Available Laboratorial two-body wear testing was carried out in order to assess effects of polypropylene modification by impregnating it with oils on friction coefficient and wear in comparison to those parameters of unmodified polypropylene, Teflon, and polyamide during operation under conditions of sliding friction without lubrication. Wear behaviour of the tested specimens was investigated using ASTM G77-98 standard wear test equipment. Recording program made it possible to visualise and record the following parameters: rotational speed and load, linear wear, friction coefficient, temperature of the specimen, and ambient temperature. In addition, wear mechanisms of the analysed materials were determined with use of scanning electron microscopy. In the case of the remaining tested polymers, the most important mechanism of wear was adhesion (PP, PTFE, PA 6.6, and PA MoS2, microcutting (PTFE, PA 6.6, and PA MoS2, fatigue wear (PTFE, forming “roll-shaped particles” combined with plastic deformation (PA 6.6 and PA MoS2, and thermal wear (PP. Impregnation of polypropylene with engine oil, gear oil, or RME results in significant reduction of friction coefficient and thus of friction torque, in relation to not only unmodified polypropylene but also the examined polyamide and Teflon.

  10. Rubber friction and tire dynamics

    International Nuclear Information System (INIS)

    Persson, B N J

    2011-01-01

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  11. Friction Material Composites Materials Perspective

    CERN Document Server

    Sundarkrishnaa, K L

    2012-01-01

    Friction Material Composites is the first of the five volumes which strongly educates and updates engineers and other professionals in braking industries, research and test labs. It explains besides the formulation of design processes and its complete manufacturing input. This book gives an idea of mechanisms of friction and how to control them by designing .The book is  useful for designers  of automotive, rail and aero industries for designing the brake systems effectively with the integration of friction material composite design which is critical. It clearly  emphasizes the driving  safety and how serious designers should  select the design input. The significance of friction material component like brake pad or a liner as an integral part of the brake system of vehicles is explained. AFM pictures at nanolevel illustrate broadly the explanations given.

  12. Size scaling of static friction.

    Science.gov (United States)

    Braun, O M; Manini, Nicola; Tosatti, Erio

    2013-02-22

    Sliding friction across a thin soft lubricant film typically occurs by stick slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Here we formulate a scaling law of the static friction force, which for a soft lubricant is predicted to decrease as f(m)+Δf/A(γ) for increasing contact area A, with γ>0. Our main finding is that the value of f(m), controlling the survival of stick slip at large size, can be evaluated by simulations of comparably small size. MD simulations of soft lubricant sliding are presented, which verify this theory.

  13. Rubber friction and tire dynamics.

    Science.gov (United States)

    Persson, B N J

    2011-01-12

    We propose a simple rubber friction law, which can be used, for example, in models of tire (and vehicle) dynamics. The friction law is tested by comparing numerical results to the full rubber friction theory (Persson 2006 J. Phys.: Condens. Matter 18 7789). Good agreement is found between the two theories. We describe a two-dimensional (2D) tire model which combines the rubber friction model with a simple mass-spring description of the tire body. The tire model is very flexible and can be used to accurately calculate μ-slip curves (and the self-aligning torque) for braking and cornering or combined motion (e.g. braking during cornering). We present numerical results which illustrate the theory. Simulations of anti-blocking system (ABS) braking are performed using two simple control algorithms.

  14. Cultural Robotics: The Culture of Robotics and Robotics in Culture

    OpenAIRE

    Hooman Samani; Elham Saadatian; Natalie Pang; Doros Polydorou; Owen Noel Newton Fernando; Ryohei Nakatsu; Jeffrey Tzu Kwan Valino Koh

    2013-01-01

    In this paper, we have investigated the concept of “Cultural Robotics” with regard to the evolution of social into cultural robots in the 21st Century. By defining the concept of culture, the potential development of a culture between humans and robots is explored. Based on the cultural values of the robotics developers, and the learning ability of current robots, cultural attributes in this regard are in the process of being formed, which would define the new concept of cultural robotics. Ac...

  15. PENGENDALIAN PID PADA ROBOT MIROSOT UPN “VETERAN” YOGYAKARTA BERBASIS SENSOR GYROSCOPE DAN ACCELEROMETER

    Directory of Open Access Journals (Sweden)

    Awang Hendrianto Pratomo

    2015-07-01

    Full Text Available MiRoSoT Robot movement is influenced by the speed control from right and left wheels. Wheels speed control on MiroSot robot is determined by parameter PID (Proportional Integral and Derevative value. PID value determined by robot position and angle. MiroSot robot movement is still not stable and can not move in accordance with the instruction have been made. Instability of the robot movement in the game is affected by friction wheels against the ground, friction gear and robot load. In this study, implemented a gyroscope and accelerometer sensors to stabilize robot movement. Based on both sensors are controlled by using a microcontroller ATmega64. Speed control system based on gyroscope and accelerometer sensor is obtained that the robot is able to face a certain angle more precisely. The accelerometer sensor is used as a parameter for the braking system, so the robot is able to move more stable without the loss of power from the motor during a reduction speed from the strategy control.

  16. Nuclear friction and chaotic motion

    International Nuclear Information System (INIS)

    Srokowski, T.; Szczurek, A.; Drozdz, S.

    1990-01-01

    The concept of nuclear friction is considered from the point of view of regular versus chaotic motion in an atomic nucleus. Using a realistic nuclear Hamiltonian it is explicitly shown that the frictional description of the gross features of nuclear collisions is adequate if the system behaves chaotically. Because of the core in the Hamiltonian, the three-body nuclear system already reveals a structure of the phase space rich enough for this concept to be applicable

  17. Slipforming - Materials effect on friction

    OpenAIRE

    Busterud, Jørgen Thomasgaard

    2016-01-01

    Master's thesis in Structural engineering Slipforming is a construction method for concrete and it is especially suited for tall constructions with simple geometry. This method have occasionally caused lifting cracks and other surface damages, due to the friction between the slipform panel and the concrete has become to high. The thesis will look at how the choice of material composition in concrete mixes in the combination of a given slipform rate would affect the friction between the ...

  18. Slow rupture of frictional interfaces

    OpenAIRE

    Sinai, Yohai Bar; Brener, Efim A.; Bouchbinder, Eran

    2011-01-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not comple...

  19. Labor Supply and Optimization Frictions

    DEFF Research Database (Denmark)

    Søgaard, Jakob Egholt

    In this paper I investigate the nature of optimization frictions by studying the labor market of Danish students. This particular labor market is an interesting case study as it features a range of special institutional settings that affect students’ incentive to earn income and comparing outcomes...... theory. More concretely I find the dominate optimization friction to be individuals’ inattention about their earnings during the year, while real adjustment cost and gradual learning appears to be of less importance....

  20. The Effect of Rolling As-Cast and Homogenized U-10Mo Samples on the Microstructure Development and Recovery Curves

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Vineet V. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Paxton, Dean M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lavender, Curt A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Burkes, Douglas [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-07-30

    microstructure. However, annealing the samples led to quick recovery in hardness as evidenced by a drop in Vickers hardness of 20%. Hot rolling was performed at 650 and 800°C. The hot-rolling mill loads (load separation force) were approximately 40 to 50% less than the cold-rolling for the same reduction and thickness. It was observed that hot rolling the samples with 50% or more reduction in thickness were responsible for dynamic recrystallization in the hot-rolled samples and led to grain refinement. Unlike the cold-rolled samples, the hot-rolled samples did not fracture the carbides and appeared to heal the casting defects. The recovery phenomenon was similar to the cold-rolled samples above the eutectoid temperatures, but owing to the refined grain size, the precipitation of the lamellar phase was far more rapid in these samples and the hardness increased more rapidly than in the cold rolled sample when heated below the eutectoid temperature. The data generated from these rolling efforts has been used to make the process modeling efforts more robust and applicable to all USHPRR partner rolling mills. The flow stress for cold rolling the samples was determined to be between 170-190 ksi, with frictional forces between 0.2 and 0.4 for the PNNL mill. The measured roll separation forces and those simulated using finite element methods for hot and cold rolling for the PNNL rolling mill were in good agreement.

  1. Tachyon constant-roll inflation

    Science.gov (United States)

    Mohammadi, A.; Saaidi, Kh.; Golanbari, T.

    2018-04-01

    The constant-roll inflation is studied where the inflaton is taken as a tachyon field. Based on this approach, the second slow-roll parameter is taken as a constant which leads to a differential equation for the Hubble parameter. Finding an exact solution for the Hubble parameter is difficult and leads us to a numerical solution for the Hubble parameter. On the other hand, since in this formalism the slow-roll parameter η is constant and could not be assumed to be necessarily small, the perturbation parameters should be reconsidered again which, in turn, results in new terms appearing in the amplitude of scalar perturbations and the scalar spectral index. Utilizing the numerical solution for the Hubble parameter, we estimate the perturbation parameter at the horizon exit time and compare it with observational data. The results show that, for specific values of the constant parameter η , we could have an almost scale-invariant amplitude of scalar perturbations. Finally, the attractor behavior for the solution of the model is presented, and we determine that the feature could be properly satisfied.

  2. A Haptic Guided Robotic System for Endoscope Positioning and Holding.

    Science.gov (United States)

    Cabuk, Burak; Ceylan, Savas; Anik, Ihsan; Tugasaygi, Mehtap; Kizir, Selcuk

    2015-01-01

    To determine the feasibility, advantages, and disadvantages of using a robot for holding and maneuvering the endoscope in transnasal transsphenoidal surgery. The system used in this study was a Stewart Platform based robotic system that was developed by Kocaeli University Department of Mechatronics Engineering for positioning and holding of endoscope. After the first use on an artificial head model, the system was used on six fresh postmortem bodies that were provided by the Morgue Specialization Department of the Forensic Medicine Institute (Istanbul, Turkey). The setup required for robotic system was easy, the time for registration procedure and setup of the robot takes 15 minutes. The resistance was felt on haptic arm in case of contact or friction with adjacent tissues. The adaptation process was shorter with the mouse to manipulate the endoscope. The endoscopic transsphenoidal approach was achieved with the robotic system. The endoscope was guided to the sphenoid ostium with the help of the robotic arm. This robotic system can be used in endoscopic transsphenoidal surgery as an endoscope positioner and holder. The robot is able to change the position easily with the help of an assistant and prevents tremor, and provides a better field of vision for work.

  3. A method to achieve comparable thermal states of car brakes during braking on the road and on a high-speed roll-stand

    Science.gov (United States)

    Wolff, Andrzej

    2010-01-01

    The temperature of a brake friction surface influences significantly the braking effectiveness. The paper describes a heat transfer process in car brakes. Using a developed program of finite element method, the temperature distributions in brake rotors (disc and drum brake) of a light truck have been calculated. As a preliminary consistency criterion of the brake thermal state in road and roll-stand braking conditions, a balance of the energy cumulated in the brake rotor has been taken into account. As the most reliable consistency criterion an equality of average temperatures of the friction surface has been assumed. The presented method allows to achieve on a roll-stand the analogical thermal states of automotive brakes, which are observed during braking in road conditions. Basing on this method, it is possible to calculate the braking time and force for a high-speed roll-stand. In contrast to the previous papers of the author, new calculation results have been presented.

  4. Calibration of Robot Reference Frames for Enhanced Robot Positioning Accuracy

    OpenAIRE

    Cheng, Frank Shaopeng

    2008-01-01

    This chapter discussed the importance and methods of conducting robot workcell calibration for enhancing the accuracy of the robot TCP positions in industrial robot applications. It shows that the robot frame transformations define the robot geometric parameters such as joint position variables, link dimensions, and joint offsets in an industrial robot system. The D-H representation allows the robot designer to model the robot motion geometry with the four standard D-H parameters. The robot k...

  5. Development of a Novel Locomotion Algorithm for Snake Robot

    International Nuclear Information System (INIS)

    Khan, Raisuddin; Billah, Md Masum; Watanabe, Mitsuru; Shafie, A A

    2013-01-01

    A novel algorithm for snake robot locomotion is developed and analyzed in this paper. Serpentine is one of the renowned locomotion for snake robot in disaster recovery mission to overcome narrow space navigation. Several locomotion for snake navigation, such as concertina or rectilinear may be suitable for narrow spaces, but is highly inefficient if the same type of locomotion is used even in open spaces resulting friction reduction which make difficulties for snake movement. A novel locomotion algorithm has been proposed based on the modification of the multi-link snake robot, the modifications include alterations to the snake segments as well elements that mimic scales on the underside of the snake body. Snake robot can be able to navigate in the narrow space using this developed locomotion algorithm. The developed algorithm surmount the others locomotion limitation in narrow space navigation

  6. Fluid-structure interaction of a rolling restrained body of revolution at high angles of attack

    Science.gov (United States)

    Degani, D.; Ishay, M.; Gottlieb, O.

    2017-03-01

    The current work investigates numerically rolling instabilities of a free-to-roll slender rigid-body of revolution placed in a wind tunnel at a high angle of attack. The resistance to the roll moment is represented by a linear torsion spring and equivalent linear damping representing friction in the bearings of a simulated wind tunnel model. The body is subjected to a three-dimensional, compressible, laminar flow. The full Navier-Stokes equations are solved using the second-order implicit finite difference Beam-Warming scheme, adapted to a curvilinear coordinate system, whereas the coupled structural second order equation of motion for roll is solved by a fourth-order Runge-Kutta method. The body consists of a 3.5-diameter tangent ogive forebody with a 7.0-diameter long cylindrical afterbody extending aft of the nose-body junction to x/D = 10.5. We describe in detail the investigation of three angles of attack 20°, 40°, and 65°, at a Reynolds number of 30 000 (based on body diameter) and a Mach number of 0.2. Three distinct configurations are investigated as follows: a fixed body, a free-to-roll body with a weak torsion spring, and a free-to-roll body with a strong torsion spring. For each angle of attack the free-to-roll configuration portrays a distinct and different behavior pattern, including bi-stable limit-cycle oscillations. The bifurcation structure incorporates both large and small amplitude periodic roll oscillations where the latter lose their periodicity with increasing stiffness of the restraining spring culminating with distinct quasiperiodic oscillations. We note that removal of an applied upstream disturbance for a restrained body does not change the magnitude or complexity of the oscillations or of the flow patterns along the body. Depending on structure characteristics and flow conditions even a small rolling moment coefficient at the relatively low angle of attack of 20° may lead to large amplitude resonant roll oscillations.

  7. Modeling Friction in Modelica with the Lund-Grenoble Friction Model

    OpenAIRE

    Aberger, Martin; Otter, Martin

    2002-01-01

    The properties of the Lund-Grenoble friction model are summarized and different types of friction elements - bearing friction, clutch, one-way clutch, are implemented in Modelica using this friction formulation. The dynamic properties of these components are determined in simulations and compared with the friction models available in the Modelica standard library. This includes also an automatic gearbox model where 6 friction elements are coupled dynamically.

  8. Educational Robotics as Mindtools

    Science.gov (United States)

    Mikropoulos, Tassos A.; Bellou, Ioanna

    2013-01-01

    Although there are many studies on the constructionist use of educational robotics, they have certain limitations. Some of them refer to robotics education, rather than educational robotics. Others follow a constructionist approach, but give emphasis only to design skills, creativity and collaboration. Some studies use robotics as an educational…

  9. ROILA : RObot Interaction LAnguage

    NARCIS (Netherlands)

    Mubin, O.

    2011-01-01

    The number of robots in our society is increasing rapidly. The number of service robots that interact with everyday people already outnumbers industrial robots. The easiest way to communicate with these service robots, such as Roomba or Nao, would be natural speech. However, the limitations

  10. Robotic Hand

    Science.gov (United States)

    1993-01-01

    The Omni-Hand was developed by Ross-Hime Designs, Inc. for Marshall Space Flight Center (MSFC) under a Small Business Innovation Research (SBIR) contract. The multiple digit hand has an opposable thumb and a flexible wrist. Electric muscles called Minnacs power wrist joints and the interchangeable digits. Two hands have been delivered to NASA for evaluation for potential use on space missions and the unit is commercially available for applications like hazardous materials handling and manufacturing automation. Previous SBIR contracts resulted in the Omni-Wrist and Omni-Wrist II robotic systems, which are commercially available for spray painting, sealing, ultrasonic testing, as well as other uses.

  11. Friction anisotropy in boronated graphite

    International Nuclear Information System (INIS)

    Kumar, N.; Radhika, R.; Kozakov, A.T.; Pandian, R.; Chakravarty, S.; Ravindran, T.R.; Dash, S.; Tyagi, A.K.

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient

  12. Friction anisotropy in boronated graphite

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, N., E-mail: niranjan@igcar.gov.in [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Radhika, R. [Crystal Growth Centre, Anna University, Chennai (India); Kozakov, A.T. [Research Institute of Physics, Southern Federal University, Rostov-on-Don (Russian Federation); Pandian, R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India); Chakravarty, S. [UGC-DAE CSR, Kalpakkam (India); Ravindran, T.R.; Dash, S.; Tyagi, A.K. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam (India)

    2015-01-01

    Graphical abstract: - Highlights: • Friction anisotropy in boronated graphite is observed in macroscopic sliding condition. • Low friction coefficient is observed in basal plane and becomes high in prismatic direction. • 3D phase of boronated graphite transformed into 2D structure after friction test. • Chemical activity is high in prismatic plane forming strong bonds between the sliding interfaces. - Abstract: Anisotropic friction behavior in macroscopic scale was observed in boronated graphite. Depending upon sliding speed and normal loads, this value was found to be in the range 0.1–0.35 in the direction of basal plane and becomes high 0.2–0.8 in prismatic face. Grazing-incidence X-ray diffraction analysis shows prominent reflection of (0 0 2) plane at basal and prismatic directions of boronated graphite. However, in both the wear tracks (1 1 0) plane become prominent and this transformation is induced by frictional energy. The structural transformation in wear tracks is supported by micro-Raman analysis which revealed that 3D phase of boronated graphite converted into a disordered 2D lattice structure. Thus, the structural aspect of disorder is similar in both the wear tracks and graphite transfer layers. Therefore, the crystallographic aspect is not adequate to explain anisotropic friction behavior. Results of X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy shows weak signature of oxygen complexes and functional groups in wear track of basal plane while these species dominate in prismatic direction. Abundance of these functional groups in prismatic plane indicates availability of chemically active sites tends to forming strong bonds between the sliding interfaces which eventually increases friction coefficient.

  13. Analysis and Development of Walking Algorithm Kinematic Model for 5-Degree of Freedom Bipedal Robot

    Directory of Open Access Journals (Sweden)

    Gerald Wahyudi Setiono

    2012-12-01

    Full Text Available A design of walking diagram and the calculation of a bipedal robot have been developed. The bipedal robot was designed and constructed with several kinds of servo bracket for the legs, two feet and a hip. Each of the bipedal robot leg was 5-degrees of freedom, three pitches (hip joint, knee joint and ankle joint and two rolls (hip joint and ankle joint. The walking algorithm of this bipedal robot was based on the triangle formulation of cosine law to get the angle value at each joint. The hip height, height of the swinging leg and the step distance are derived based on linear equation. This paper discussed the kinematic model analysis and the development of the walking diagram of the bipedal robot. Kinematics equations were derived, the joint angles were simulated and coded into Arduino board to be executed to the robot.

  14. Experimental and numerical study on single-phase flow characteristics of natural circulation system with heated narrow rectangular channel under rolling motion condition

    International Nuclear Information System (INIS)

    Yu, Shengzhi; Wang, Jianjun; Yan, Ming; Yan, Changqi; Cao, Xiaxin

    2017-01-01

    Highlights: • The phasic difference between flow rate and frictional pressure drop is negligible. • Effect mechanism of rolling motion on flow behaviors of NC is interpreted. • The startup model is proposed and verified. • Steady-state correlations are feasible to predict transient resistance. • The in-house code can simulate instantaneous flow behaviors of NC correctly. - Abstract: Effects of rolling motion on flow characteristics in a natural circulation system were investigated experimentally and numerically. The numerical results from validated code were mainly used to provide detailed information for the discussion and analysis of experimental results. The results indicate that under rolling motion condition, the phasic difference between flow rate and frictional pressure drop of narrow rectangular channel is negligible. Angular acceleration is the eigenvalue for the effects of rolling motion on flow rate under single-phase natural circulation condition. When angular acceleration is approximately equal, even though either the angle or the period of rolling motion is different, peak, trough and time-averaged values of flow rate are approximately equal. Under rolling motion and single-phase natural circulation conditions, the phenomenon that dimensionless time-averaged mass flow rate is smaller than that under steady state condition is controlled by the nonlinear relationship between mass flow rate and the resistance of loop. The factor also causes the result that the absolute difference of dimensionless flow rate between peak and steady state is smaller than that between trough and steady state. The startup model which is proposed in present paper can be used to predict the flow characteristics of single-phase natural circulation system at startup stage of rolling motion favorably. The self-developed code can simulate instantaneous flow characteristics of single-phase natural circulation system under rolling motion and steady state conditions

  15. Real-Time Dynamic Observation of Micro-Friction on the Contact Interface of Friction Lining

    Science.gov (United States)

    Zhang, Dekun; Chen, Kai; Guo, Yongbo

    2018-01-01

    This paper aims to investigate the microscopic friction mechanism based on in situ microscopic observation in order to record the deformation and contact situation of friction lining during the frictional process. The results show that friction coefficient increased with the shear deformation and energy loss of the surfacee, respectively. Furthermore, the friction mechanism mainly included adhesive friction in the high-pressure and high-speed conditions, whereas hysteresis friction was in the low-pressure and low-speed conditions. The mixed-friction mechanism was in the period when the working conditions varied from high pressure and speed to low pressure and speed. PMID:29498677

  16. Autonomous undulatory serpentine locomotion utilizing body dynamics of a fluidic soft robot

    International Nuclear Information System (INIS)

    Onal, Cagdas D; Rus, Daniela

    2013-01-01

    Soft robotics offers the unique promise of creating inherently safe and adaptive systems. These systems bring man-made machines closer to the natural capabilities of biological systems. An important requirement to enable self-contained soft mobile robots is an on-board power source. In this paper, we present an approach to create a bio-inspired soft robotic snake that can undulate in a similar way to its biological counterpart using pressure for actuation power, without human intervention. With this approach, we develop an autonomous soft snake robot with on-board actuation, power, computation and control capabilities. The robot consists of four bidirectional fluidic elastomer actuators in series to create a traveling curvature wave from head to tail along its body. Passive wheels between segments generate the necessary frictional anisotropy for forward locomotion. It takes 14 h to build the soft robotic snake, which can attain an average locomotion speed of 19 mm s −1 . (paper)

  17. Bio-inspired enhancement of friction and adhesion at the polydimethylsiloxane-intestine interface and biocompatibility characterization

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Hongyu, E-mail: zhanghyu@tsinghua.edu.cn [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Wang, Yi [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Vasilescu, Steven [School of Mathematics and Physical Science, Faculty of Science, University of Technology Sydney, New South Wales 2007 (Australia); Gu, Zhibin [Institute of Electronics, Chinese Academy of Sciences, Beijing 100190 (China); Sun, Tao [State Key Laboratory of Tribology, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)

    2017-05-01

    An active navigation of self-propelled miniaturized robot along the intestinal tract without injuring the soft tissue remains a challenge as yet. Particularly in this case an effective control of the interfacial friction and adhesion between the material used and the soft tissue is crucial. In the present study, we investigated the frictional and adhesive properties between polydimethylsiloxane (PDMS, microscopically patterned with micro-pillar arrays and non-patterned with a flat surface) and rabbit small intestinal tract using a universal material tester. The friction coefficient-time plot and adhesive force-time plot were recorded during the friction test (sliding speed: 0.25 mm/s; normal loading: 0.4 N) and adhesion test (preloading: 0.5 N; hoisting speed: 2.5 × 10{sup −3} mm/s). In addition, biocompatibility of the PDMS samples was characterized in terms of cell morphology (scanning electron microscope) and cell cytotoxicity (alamarBlue assay) using human vascular endothelial cells (HUVECs). The results demonstrated that the interfacial friction (0.27 vs 0.19) and adhesion (34.9 mN vs 26.7 mN) were greatly increased using microscopically patterned PDMS, in comparison with non-patterned PDMS. HUVECs adhered to and proliferated on non-patterned/microscopically patterned PDMS very well, with a relative cell viability of about 90% following seeding at 1 d, 3 d, and 5 d. The favorable enhancement of the frictional and adhesive properties, along with the excellent biocompatibility of the microscopically patterned PDMS, makes it a propitious choice for clinical application of self-propelled miniaturized robots. - Highlights: • Micro-pillars enhanced friction and adhesion between PDMS and intestinal tract. • Micro-patterned PDMS showed good cell morphology and cytotoxicity using HUVECs. • Micro-pattern technology may be applied in self-propelled miniaturized robot.

  18. Bio-inspired enhancement of friction and adhesion at the polydimethylsiloxane-intestine interface and biocompatibility characterization

    International Nuclear Information System (INIS)

    Zhang, Hongyu; Wang, Yi; Vasilescu, Steven; Gu, Zhibin; Sun, Tao

    2017-01-01

    An active navigation of self-propelled miniaturized robot along the intestinal tract without injuring the soft tissue remains a challenge as yet. Particularly in this case an effective control of the interfacial friction and adhesion between the material used and the soft tissue is crucial. In the present study, we investigated the frictional and adhesive properties between polydimethylsiloxane (PDMS, microscopically patterned with micro-pillar arrays and non-patterned with a flat surface) and rabbit small intestinal tract using a universal material tester. The friction coefficient-time plot and adhesive force-time plot were recorded during the friction test (sliding speed: 0.25 mm/s; normal loading: 0.4 N) and adhesion test (preloading: 0.5 N; hoisting speed: 2.5 × 10 −3 mm/s). In addition, biocompatibility of the PDMS samples was characterized in terms of cell morphology (scanning electron microscope) and cell cytotoxicity (alamarBlue assay) using human vascular endothelial cells (HUVECs). The results demonstrated that the interfacial friction (0.27 vs 0.19) and adhesion (34.9 mN vs 26.7 mN) were greatly increased using microscopically patterned PDMS, in comparison with non-patterned PDMS. HUVECs adhered to and proliferated on non-patterned/microscopically patterned PDMS very well, with a relative cell viability of about 90% following seeding at 1 d, 3 d, and 5 d. The favorable enhancement of the frictional and adhesive properties, along with the excellent biocompatibility of the microscopically patterned PDMS, makes it a propitious choice for clinical application of self-propelled miniaturized robots. - Highlights: • Micro-pillars enhanced friction and adhesion between PDMS and intestinal tract. • Micro-patterned PDMS showed good cell morphology and cytotoxicity using HUVECs. • Micro-pattern technology may be applied in self-propelled miniaturized robot.

  19. Fluid management in roll-to-roll nanoimprint lithography

    Science.gov (United States)

    Jain, A.; Bonnecaze, R. T.

    2013-06-01

    The key process parameters of UV roll-to-roll nanoimprint lithography are identified from an analysis of the fluid, curing, and peeling dynamics. The process includes merging of droplets of imprint material, curing of the imprint material from a viscous liquid to elastic solid resist, and pattern replication and detachment of the resist from template. The time and distances on the web or rigid substrate over which these processes occur are determined as function of the physical properties of the uncured liquid, the cured solid, and the roller configuration. The upper convected Maxwell equation is used to model the viscoelastic liquid and to calculate the force on the substrate and the torque on the roller. The available exposure time is found to be the rate limiting parameter and it is O(√Rho /uo), where R is the radius of the roller, ho is minimum gap between the roller and web, and uo is the velocity of the web. The residual layer thickness of the resist should be larger than the gap between the roller and the substrate to ensure complete feature filling and optimal pattern replication. For lower residual layer thickness, the droplets may not merge to form a continuous film for pattern transfer.

  20. Modular Robotic Wearable

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Pagliarini, Luigi

    2009-01-01

    In this concept paper we trace the contours and define a new approach to robotic systems, composed of interactive robotic modules which are somehow worn on the body. We label such a field as Modular Robotic Wearable (MRW). We describe how, by using modular robotics for creating wearable....... Finally, by focusing on the intersection of the combination modular robotic systems, wearability, and bodymind we attempt to explore the theoretical characteristics of such approach and exploit the possible playware application fields....

  1. Structural Damping with Friction Beams

    Directory of Open Access Journals (Sweden)

    L. Gaul

    2008-01-01

    Full Text Available In the last several years, there has been increasing interest in the use of friction joints for enhancing damping in structures. The joints themselves are responsible for the major part of the energy dissipation in assembled structures. The dissipated work in a joint depends on both the applied normal force and the excitation force. For the case of a constant amplitude excitation force, there is an optimal normal force which maximizes the damping. A ‘passive’ approach would be employed in this instance. In most cases however, the excitation force, as well as the interface parameters such as the friction coefficient, normal pressure distribution, etc., are not constant. In these cases, a ‘semi-active’ approach, which implements an active varying normal force, is necessary. For the ‘passive’ and ‘semi-active’ approaches, the normal force has to be measured. Interestingly, since the normal force in a friction joint influences the local stiffness, the natural frequencies of the assembled structure can be tuned by adjusting the normal force. Experiments and simulations are performed for a simple laboratory structure consisting of two superposed beams with friction in the interface. Numerical simulation of the friction interface requires non-linear models. The response of the double beam system is simulated using a numerical algorithm programmed in MATLAB which models point-to-point friction with the Masing friction model. Numerical predictions and measurements of the double beam free vibration response are compared. A practical application is then described, in which a friction beam is used to damp the vibrations of the work piece table on a milling machine. The increased damping of the table reduces vibration amplitudes, which in turn results in enhanced surface quality of the machined parts, reduction in machine tool wear, and potentially higher feed rates. Optimal positioning of the friction beams is based on knowledge of the mode

  2. The Role of Modular Robotics in Mediating Nonverbal Social Exchanges

    DEFF Research Database (Denmark)

    Marti, P; Giusti, L; Lund, Henrik Hautop

    2009-01-01

    This paper outlines the use of modular robotics to encourage and facilitate nonverbal communication during therapeutic intervention in dementia care. A set of new socially interactive modular robotic devices called rolling pins (RPs) has been designed and developed to assist the therapist...... is that they are able to communicate with each other or with other devices equipped with the same radio communication technology. The RPs are usually used in pairs, as the local feedback of an RP can be set depending not only on its own speed and orientation but also on the speed and the orientation of the peer RP...

  3. Versatile Friction Stir Welding/Friction Plug Welding System

    Science.gov (United States)

    Carter, Robert

    2006-01-01

    A proposed system of tooling, machinery, and control equipment would be capable of performing any of several friction stir welding (FSW) and friction plug welding (FPW) operations. These operations would include the following: Basic FSW; FSW with automated manipulation of the length of the pin tool in real time [the so-called auto-adjustable pin-tool (APT) capability]; Self-reacting FSW (SRFSW); SR-FSW with APT capability and/or real-time adjustment of the distance between the front and back shoulders; and Friction plug welding (FPW) [more specifically, friction push plug welding] or friction pull plug welding (FPPW) to close out the keyhole of, or to repair, an FSW or SR-FSW weld. Prior FSW and FPW systems have been capable of performing one or two of these operations, but none has thus far been capable of performing all of them. The proposed system would include a common tool that would have APT capability for both basic FSW and SR-FSW. Such a tool was described in Tool for Two Types of Friction Stir Welding (MFS- 31647-1), NASA Tech Briefs, Vol. 30, No. 10 (October 2006), page 70. Going beyond what was reported in the cited previous article, the common tool could be used in conjunction with a plug welding head to perform FPW or FPPW. Alternatively, the plug welding head could be integrated, along with the common tool, into a FSW head that would be capable of all of the aforementioned FSW and FPW operations. Any FSW or FPW operation could be performed under any combination of position and/or force control.

  4. Hexapod Robot

    Science.gov (United States)

    Begody, Ericka

    2016-01-01

    The project I am working on at NASA-Johnson Space Center in Houston, TX is a hexapod robot. This project was started by various engineers at the Trick Lab. The goal of this project is to have the hexapod track a yellow ball or possibly another object from left to right and up/down. The purpose is to have it track an object like a real creature. The project will consist of using software and hardware. This project started with a hexapod robot which uses a senor bar to track a yellow ball but with a limited field of vision. The sensor bar acts as the robots "head." Two servos will be added to the hexapod to create flexion and extension of the head. The neck and head servos will have to be programmed to be added to the original memory map of the existing servos. I will be using preexisting code. The main programming language that will be used to add to the preexisting code is C++. The trick modeling and simulation software will also be used in the process to improve its tracking and movement. This project will use a trial and error approach, basically seeing what works and what does not. The first step is to initially understand how the hexapod works. To get a general understanding of how the hexapod maneuvers and plan on how to had a neck and head servo which works with the rest of the body. The second step would be configuring the head and neck servos with the leg servos. During this step, limits will be programmed specifically for the each servo. By doing this, the servo is limited to how far it can rotate both clockwise and counterclockwise and this is to prevent hardware damage. The hexapod will have two modes in which it works in. The first mode will be if the sensor bar does not detect an object. If the object it is programmed to look for is not in its view it will automatically scan from left to right 3 times then up and down once. The second mode will be if the sensor bar does detect the object. In this mode the hexapod will track the object from left to

  5. The real time rolling shutter

    OpenAIRE

    Monaghan, David; O'Connor, Noel E.; Cleary, Anne; Connolly, Denis

    2015-01-01

    From an early age children are often told either, you are creative you should do art but stay away from science and maths. Or that you are mathematical you should do science but you're not that creative. Compounding this there also exist some traditional barriers of artistic rhetoric that say, "don't touch, don't think and don't be creative, we've already done that for you, you can just look...". The Real Time Rolling Shutter is part of a collaborative Art/Science partnership whose core tenet...

  6. Grooved tube plug rolls in

    International Nuclear Information System (INIS)

    Krausser, P.

    1991-01-01

    The removable plugs used to date by the Power Generation Group (KWU) of Siemens to seal defective steam generator tubes have a good track record. Their sealing principle is based on the elastic tensioning of three seal disks against the inside wall of the tube. Now a further removable plug is available -a roll-in plug with a metal-coated surface. It is particularly suitable for use in the roller-expanded zone of the tubes at the tube sheet. The plugs can be used in both Siemens-KWU steam generators and in steam generators manufactured in compliance with the guidelines of the ASME Code. (author)

  7. Slow rupture of frictional interfaces

    Science.gov (United States)

    Bar Sinai, Yohai; Brener, Efim A.; Bouchbinder, Eran

    2012-02-01

    The failure of frictional interfaces and the spatiotemporal structures that accompany it are central to a wide range of geophysical, physical and engineering systems. Recent geophysical and laboratory observations indicated that interfacial failure can be mediated by slow slip rupture phenomena which are distinct from ordinary, earthquake-like, fast rupture. These discoveries have influenced the way we think about frictional motion, yet the nature and properties of slow rupture are not completely understood. We show that slow rupture is an intrinsic and robust property of simple non-monotonic rate-and-state friction laws. It is associated with a new velocity scale cmin, determined by the friction law, below which steady state rupture cannot propagate. We further show that rupture can occur in a continuum of states, spanning a wide range of velocities from cmin to elastic wave-speeds, and predict different properties for slow rupture and ordinary fast rupture. Our results are qualitatively consistent with recent high-resolution laboratory experiments and may provide a theoretical framework for understanding slow rupture phenomena along frictional interfaces.

  8. ROLL OUT THE TALENT : Final project report

    OpenAIRE

    Eerola, Tuomas; Tuominen, Pirjo; Hakkarainen, Riitta-Liisa; Laurikainen, Marja; Mero, Niina

    2014-01-01

    The ROLL OUT THE TALENT project was born out of the desire to recognise and support the strengths of vocational students and to develop new and innovative operating models. ROLL OUT THE TALENT promoted regional cooperation between institutes and companies. The project produced operating and study path models that take into consideration the individual strengths of vocational students and the principles of lifelong learning. This is the final report of the ROLL OUT THE TALENT project, and ...

  9. Three Three-Axis IEPE Accelerometers on the Inner Liner of a Tire for Finding the Tire-Road Friction Potential Indicators.

    Science.gov (United States)

    Niskanen, Arto; Tuononen, Ari J

    2015-08-05

    Direct tire-road contact friction estimation is essential for future autonomous cars and active safety systems. Friction estimation methods have been proposed earlier for driving conditions in the presence of a slip angle or slip ratio. However, the estimation of the friction from a freely-rolling tire is still an unsolved topic. Knowing the existing friction potential would be beneficial since vehicle control systems could be adjusted before any remarkable tire force has been produced. Since accelerometers are well-known and robust, and thus a promising sensor type for intelligent tires, this study uses three three-axis IEPE accelerometers on the inner liner of a tire to detect friction potential indicators on two equally smooth surfaces with different friction levels. The equal roughness was chosen for both surfaces in order to study the friction phenomena by neglecting the effect of surface texture on vibrations. The acceleration data before the contact is used to differentiate the two friction levels between the tire and the road. In addition, the contact lengths from the three accelerometers are used to validate the acceleration data. A method to differentiate the friction levels on the basis of the acceleration signal is also introduced.

  10. Three Three-Axis IEPE Accelerometers on the Inner Liner of a Tire for Finding the Tire-Road Friction Potential Indicators

    Directory of Open Access Journals (Sweden)

    Arto Niskanen

    2015-08-01

    Full Text Available Direct tire-road contact friction estimation is essential for future autonomous cars and active safety systems. Friction estimation methods have been proposed earlier for driving conditions in the presence of a slip angle or slip ratio. However, the estimation of the friction from a freely-rolling tire is still an unsolved topic. Knowing the existing friction potential would be beneficial since vehicle control systems could be adjusted before any remarkable tire force has been produced. Since accelerometers are well-known and robust, and thus a promising sensor type for intelligent tires, this study uses three three-axis IEPE accelerometers on the inner liner of a tire to detect friction potential indicators on two equally smooth surfaces with different friction levels. The equal roughness was chosen for both surfaces in order to study the friction phenomena by neglecting the effect of surface texture on vibrations. The acceleration data before the contact is used to differentiate the two friction levels between the tire and the road. In addition, the contact lengths from the three accelerometers are used to validate the acceleration data. A method to differentiate the friction levels on the basis of the acceleration signal is also introduced.

  11. Influence of various base oils on friction and power loss in gears; Einfluss verschiedener Grundoele auf Reibung und Verlustleistung in Zahnradgetrieben

    Energy Technology Data Exchange (ETDEWEB)

    Doleschel, A.; Michaelis, K.; Hoehn, B.R.

    2001-03-01

    The frictional behaviour of synthetic lubricants was systematically investigated in a twin disc test rig and a back-to-back gear test rig. For 22 lubricants (mineral oil, polyalfaolefin (PAO), polyglycol (PG), ester and mixtures) the coefficient of friction was measured in the twin disc test rig, dependant on pressure, oil temperature, rolling and sliding velocity. In the gear test rig pressure and velocity was varied for 9 lubricants. The mineral oil shows an estimated coefficient of friction of about {mu} >> 0.045, the synthetic lubricants have a lower coefficient of friction. In the twin disc test rig the lowest coefficient of friction with PG as low as 20% of the coefficient of mineral oil was measured, depending on the mixture of EO:PO. In the gear test rig such low coefficients of friction were not measured, but still values of 60% compared to mineral oil were obtained. Esters show in the twin disc test rig a coefficient of friction in the range of 30% to 100% of the coefficient of friction of mineral oil, in the gear test rig in the range of 60% to 100%. From these investigations a calculation method for the coefficient of friction in disc and gear contacts was derived. With these equations the power loss and efficiency of transmissions in practice, lubricated with synthetic gear oils can be evaluated. (orig.)

  12. Nonlinear friction model for servo press simulation

    Science.gov (United States)

    Ma, Ninshu; Sugitomo, Nobuhiko; Kyuno, Takunori; Tamura, Shintaro; Naka, Tetsuo

    2013-12-01

    The friction coefficient was measured under an idealized condition for a pulse servo motion. The measured friction coefficient and its changing with both sliding distance and a pulse motion showed that the friction resistance can be reduced due to the re-lubrication during unloading process of the pulse servo motion. Based on the measured friction coefficient and its changes with sliding distance and re-lubrication of oil, a nonlinear friction model was developed. Using the newly developed the nonlinear friction model, a deep draw simulation was performed and the formability was evaluated. The results were compared with experimental ones and the effectiveness was verified.

  13. HoverBots: Precise Locomotion Using Robots That Are Designed for Manufacturability

    Directory of Open Access Journals (Sweden)

    Markus P. Nemitz

    2017-11-01

    Full Text Available Scaling up robot swarms to collectives of hundreds or even thousands without sacrificing sensing, processing, and locomotion capabilities is a challenging problem. Low-cost robots are potentially scalable, but the majority of existing systems have limited capabilities, and these limitations substantially constrain the type of experiments that could be performed by robotics researchers. As an alternative to increasing the quantity of robots by reducing their functionality, we have developed a new technology that delivers increased functionality at low-cost. In this study, we present a comprehensive literature review on the most commonly used locomotion strategies of swarm robotic systems. We introduce a new type of low-friction locomotion—active low-friction locomotion—and we show its first implementation in the HoverBot system. The HoverBot system consists of an air levitation and magnet table, and a HoverBot agent. HoverBot agents are levitating circuit boards that we have equipped with an array of planar coils and a Hall-effect sensor. The HoverBot agent uses its coils to pull itself toward magnetic anchors that are embedded into a levitation table. These robots use active low-friction locomotion; consist of only surface-mount components; circumvent actuator calibration; are capable of odometry by using a single Hall-effect sensor; and perform precise movement. We conducted three hours of experimental evaluation of the HoverBot system in which we observed the system performing more than 10,000 steps. We also demonstrate formation movement, random collision, and straight collisions with two robots. This study demonstrates that active low-friction locomotion is an alternative to wheeled and slip-stick locomotion in the field of swarm robotics.

  14. Interlayer adhesion in roll-to-roll processed flexible inverted polymer solar cells

    KAUST Repository

    Dupont, Stephanie R.; Oliver, Mark; Krebs, Frederik C.; Dauskardt, Reinhold H.

    2012-01-01

    The interlayer adhesion of roll-to-roll processed flexible inverted P3HT:PCBM bulk heterojunction (BHJ) polymer solar cells is reported. Poor adhesion between adjacent layers may result in loss of device performance from delamination driven

  15. Parameter Identification of Static Friction Based on An Optimal Exciting Trajectory

    Science.gov (United States)

    Tu, X.; Zhao, P.; Zhou, Y. F.

    2017-12-01

    In this paper, we focus on how to improve the identification efficiency of friction parameters in a robot joint. First, the static friction model that has only linear dependencies with respect to their parameters is adopted so that the servomotor dynamics can be linearized. In this case, the traditional exciting trajectory based on Fourier series is modified by replacing the constant term with quintic polynomial to ensure the boundary continuity of speed and acceleration. Then, the Fourier-related parameters are optimized by genetic algorithm(GA) in which the condition number of regression matrix is set as the fitness function. At last, compared with the constant-velocity tracking experiment, the friction parameters from the exciting trajectory experiment has the similar result with the advantage of time reduction.

  16. Radiometric study of creep in ingot rolling

    International Nuclear Information System (INIS)

    Kubicek, P.; Zamyslovsky, Z.; Uherek, J.

    The radiometric study of creep during ingot rolling performed in the rolling mill of the Vitkovice Iron and Steel Works and the first results are described. Selected sites in 3 to 8 ton ingots were labelled with 2 to 3.7x10 5 Bq of 60 Co and after rolling into blocks, the transposition of the labelled sites of the ingots was investigated. The results indicate creep during rolling, local extension in certain sites under study and help to determine the inevitable bottom crop incurred in the forming. Finally, the requirements put on the radiometric apparatus for the next stages of technological research are presented. (author)

  17. METHOD OF HOT ROLLING URANIUM METAL

    Science.gov (United States)

    Kaufmann, A.R.

    1959-03-10

    A method is given for quickly and efficiently hot rolling uranium metal in the upper part of the alpha phase temperature region to obtain sound bars and sheets possessing a good surface finish. The uranium metal billet is heated to a temperature in the range of 1000 deg F to 1220 deg F by immersion iii a molten lead bath. The heated billet is then passed through the rolls. The temperature is restored to the desired range between successive passes through the rolls, and the rolls are turned down approximately 0.050 inch between successive passes.

  18. High precision redundant robotic manipulator

    International Nuclear Information System (INIS)

    Young, K.K.D.

    1998-01-01

    A high precision redundant robotic manipulator for overcoming contents imposed by obstacles or imposed by a highly congested work space is disclosed. One embodiment of the manipulator has four degrees of freedom and another embodiment has seven degrees of freedom. Each of the embodiments utilize a first selective compliant assembly robot arm (SCARA) configuration to provide high stiffness in the vertical plane, a second SCARA configuration to provide high stiffness in the horizontal plane. The seven degree of freedom embodiment also utilizes kinematic redundancy to provide the capability of avoiding obstacles that lie between the base of the manipulator and the end effector or link of the manipulator. These additional three degrees of freedom are added at the wrist link of the manipulator to provide pitch, yaw and roll. The seven degrees of freedom embodiment uses one revolute point per degree of freedom. For each of the revolute joints, a harmonic gear coupled to an electric motor is introduced, and together with properly designed based servo controllers provide an end point repeatability of less than 10 microns. 3 figs

  19. Fabrication of cold-rolled bands of the alloy-ehi 702 in rolls

    International Nuclear Information System (INIS)

    Zhuchin, V.N.; Gindin, A.Sh.; Shaburov, V.E.; Vladimirov, S.M.; Sokolov, V.A.; Shavkun, V.V.; Perepelitsa, I.V.; Markov, V.V.; Naymov, E.P.; Evstaf'ev, P.P.

    1977-01-01

    The questions are discussed, connected with the manufacture of cold-rolled strip of alloy EI702 in reels from strip blanks. It has been established that in the manufacture of hot-rolled stock from EI702 slabs it is necessary to use powerful rolling equipment because of high resistance to deformation. The reel method for manufacturing EI702 alloy improves the rolled stock and increases percentage of serviceable stock, as well as the output

  20. The influence of the vane on the lubrication characteristics between the vane and the rolling piston of a rotary compressor

    International Nuclear Information System (INIS)

    Cho, Ihn Sung; Jung, Jae Youn

    2006-01-01

    The rolling piston type rotary compressor has been widely used for refrigeration and air -conditioning systems due to its compactness and high-speed operation. The present analysis is part of a research program directed toward maximizing the advantages of refrigerant compressors. The study of lubrication characteristics in the critical sliding component is essential for the design of refrigerant compressors. Therefore, theoretical investigation of the lubrication characteristics of a rotary compressor being used for refrigeration and air-conditioning systems was investigated. The Newton-Raphson method was used for a partial elastohydrodynamic lubrication analysis between the vane and the rolling piston of a rotary compressor. The results demonstrated that the vane thickness and the center line position of the vane significantly influenced the friction force and the energy loss between the vane and the rolling piston

  1. Boundary element analysis of stress singularity in dissimilar metals by friction welding

    International Nuclear Information System (INIS)

    Chung, N. Y.; Park, C. H.

    2012-01-01

    Friction welded dissimilar metals are widely applied in automobiles, rolling stocks, machine tools, and various engineering fields. Dissimilar metals have several advantages over homogeneous metals, including high strength, material property, fatigue endurance, impact absorption, high reliability, and vibration reduction. Due to the increased use of these metals, understanding their behavior under stress conditions is necessary, especially the analysis of stress singularity on the interface of friction-welded dissimilar metals. To establish a strength evaluation method and a fracture criterion, it is necessary to analyze stress singularity on the interface of dissimilar metals with welded flashes by friction welding under various loads and temperature conditions. In this paper, a method analyzing stress singularity for the specimens with and without flashes set in friction welded dissimilar metals is introduced using the boundary element method. The stress singularity index (λ) and the stress singularity factor (Γ) at the interface edge are computed from the stress analysis results. The shape and flash thickness, interface length, residual stress, and load are considered in the computation. Based on these results, the variations of interface length (c) and the ratio of flash thickness (t2 t1) greatly influence the stress singularity factors at the interface edge of friction welded dissimilar metals. The stress singularity factors will be a useful fracture parameter that considers stress singularity on the interface of dissimilar metals

  2. Investigation of the rolling motion of a hollow cylinder using a smartphone’s digital compass

    Science.gov (United States)

    Wattanayotin, Phattara; Puttharugsa, Chokchai; Khemmani, Supitch

    2017-07-01

    This study used a smartphone’s digital compass to observe the rolling motion of a hollow cylinder on an inclined plane. The smartphone (an iPhone 4s) was attached to the end of one side of a hollow cylinder to record the experimental data using the SensorLog application. In the experiment, the change of angular position was measured by the smartphone’s digital compass. The obtained results were then analyzed and calculated to determine various parameters of the motion, such as the angular velocity, angular acceleration, critical angle, and coefficient of static friction. The experimental results obtained from using the digital compass were compared with those obtained from using a gyroscope sensor. Moreover, the results obtained from both sensors were consistent with the calculations for the rolling motion. We expect that this experiment will be valuable for use in physics laboratories.

  3. Rolling into spatial disorientation: Simulator demonstration of the post-roll (Gillingham) illusion

    NARCIS (Netherlands)

    Nooij, S.A.E.; Groen, E.L.

    2011-01-01

    Introduction: Spatial disorientation (SD) is still a contributing factor in many aviation accidents, stressing the need for adequate SD training scenarios. In this article we focused on the post-roll effect (the sensation of rolling back after a roll maneuver, such as an entry of a coordinated turn)

  4. Machine Learning of Fault Friction

    Science.gov (United States)

    Johnson, P. A.; Rouet-Leduc, B.; Hulbert, C.; Marone, C.; Guyer, R. A.

    2017-12-01

    We are applying machine learning (ML) techniques to continuous acoustic emission (AE) data from laboratory earthquake experiments. Our goal is to apply explicit ML methods to this acoustic datathe AE in order to infer frictional properties of a laboratory fault. The experiment is a double direct shear apparatus comprised of fault blocks surrounding fault gouge comprised of glass beads or quartz powder. Fault characteristics are recorded, including shear stress, applied load (bulk friction = shear stress/normal load) and shear velocity. The raw acoustic signal is continuously recorded. We rely on explicit decision tree approaches (Random Forest and Gradient Boosted Trees) that allow us to identify important features linked to the fault friction. A training procedure that employs both the AE and the recorded shear stress from the experiment is first conducted. Then, testing takes place on data the algorithm has never seen before, using only the continuous AE signal. We find that these methods provide rich information regarding frictional processes during slip (Rouet-Leduc et al., 2017a; Hulbert et al., 2017). In addition, similar machine learning approaches predict failure times, as well as slip magnitudes in some cases. We find that these methods work for both stick slip and slow slip experiments, for periodic slip and for aperiodic slip. We also derive a fundamental relationship between the AE and the friction describing the frictional behavior of any earthquake slip cycle in a given experiment (Rouet-Leduc et al., 2017b). Our goal is to ultimately scale these approaches to Earth geophysical data to probe fault friction. References Rouet-Leduc, B., C. Hulbert, N. Lubbers, K. Barros, C. Humphreys and P. A. Johnson, Machine learning predicts laboratory earthquakes, in review (2017). https://arxiv.org/abs/1702.05774Rouet-LeDuc, B. et al., Friction Laws Derived From the Acoustic Emissions of a Laboratory Fault by Machine Learning (2017), AGU Fall Meeting Session S025

  5. Determination of Residual Forces in Mechanisms Assembled by Edge-Form Rolling

    Directory of Open Access Journals (Sweden)

    K. Turgut Gürsel

    2011-03-01

    Full Text Available Steering and suspension systems are components that supply driving safety in vehicles. For a correct working the mechanisms of these systems consist of many ball-joints that have different functions. Generally the ball-joints are assembled to systems in press-fit without any gaps, but even with residual forces. On the other hand excessive tightness causes high moments, which requires additional processes of manufacturing. But low tightness also creates gaps in joints. None of these conditions are desired. Manufacturing a ball-race that has long-life, low-friction and provides required working angles in every road condition, can be designed after long test processes and sample productions including lots of improvements. An important element of steering systems in vehicles is suspension ball-race that can be manufactured by assembling with plastic deformation after designing the ball-joint. In this study, during the manufacturing of the suspension ball-race supplying the motion transmission, the edge-form rolling process that is a subsection of rolling process of manufacturing methods based on plastic deformation was examined. Effects of pressure forces occurring after edge-form rolling in bearing systems at different values were studied by changing operation pressure of edge form rolling by means of specific numerical simulations.

  6. Next generation light robotic

    DEFF Research Database (Denmark)

    Villangca, Mark Jayson; Palima, Darwin; Banas, Andrew Rafael

    2017-01-01

    -assisted surgery imbibes surgeons with superhuman abilities and gives the expression “surgical precision” a whole new meaning. Still in its infancy, much remains to be done to improve human-robot collaboration both in realizing robots that can operate safely with humans and in training personnel that can work......Conventional robotics provides machines and robots that can replace and surpass human performance in repetitive, difficult, and even dangerous tasks at industrial assembly lines, hazardous environments, or even at remote planets. A new class of robotic systems no longer aims to replace humans...... with so-called automatons but, rather, to create robots that can work alongside human operators. These new robots are intended to collaborate with humans—extending their abilities—from assisting workers on the factory floor to rehabilitating patients in their homes. In medical robotics, robot...

  7. Distributed Robotics Education

    DEFF Research Database (Denmark)

    Lund, Henrik Hautop; Pagliarini, Luigi

    2011-01-01

    Distributed robotics takes many forms, for instance, multirobots, modular robots, and self-reconfigurable robots. The understanding and development of such advanced robotic systems demand extensive knowledge in engineering and computer science. In this paper, we describe the concept of a distribu......Distributed robotics takes many forms, for instance, multirobots, modular robots, and self-reconfigurable robots. The understanding and development of such advanced robotic systems demand extensive knowledge in engineering and computer science. In this paper, we describe the concept...... to be changed, related to multirobot control and human-robot interaction control from virtual to physical representation. The proposed system is valuable for bringing a vast number of issues into education – such as parallel programming, distribution, communication protocols, master dependency, connectivity...

  8. An Adaptive Robot Game

    DEFF Research Database (Denmark)

    Hansen, Søren Tranberg; Svenstrup, Mikael; Dalgaard, Lars

    2010-01-01

    The goal of this paper is to describe an adaptive robot game, which motivates elderly people to do a regular amount of physical exercise while playing. One of the advantages of robot based games is that the initiative to play can be taken autonomously by the robot. In this case, the goal is to im......The goal of this paper is to describe an adaptive robot game, which motivates elderly people to do a regular amount of physical exercise while playing. One of the advantages of robot based games is that the initiative to play can be taken autonomously by the robot. In this case, the goal...... is to improve the mental and physical state of the user by playing a physical game with the robot. Ideally, a robot game should be simple to learn but difficult to master, providing an appropriate degree of challenge for players with different skills. In order to achieve that, the robot should be able to adapt...

  9. Robotic intelligence kernel

    Science.gov (United States)

    Bruemmer, David J [Idaho Falls, ID

    2009-11-17

    A robot platform includes perceptors, locomotors, and a system controller. The system controller executes a robot intelligence kernel (RIK) that includes a multi-level architecture and a dynamic autonomy structure. The multi-level architecture includes a robot behavior level for defining robot behaviors, that incorporate robot attributes and a cognitive level for defining conduct modules that blend an adaptive interaction between predefined decision functions and the robot behaviors. The dynamic autonomy structure is configured for modifying a transaction capacity between an operator intervention and a robot initiative and may include multiple levels with at least a teleoperation mode configured to maximize the operator intervention and minimize the robot initiative and an autonomous mode configured to minimize the operator intervention and maximize the robot initiative. Within the RIK at least the cognitive level includes the dynamic autonomy structure.

  10. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    The relationship between digital and analogue is often constructed as one of opposition. The perception that the world is permeated with underlying patterns of data, describing events and matter alike, suggests that information can be understood apart from the substance to which it is associated......, and that its encoded logic can be constructed and reconfigured as an isolated entity. This disembodiment of information from materiality implies that an event like a thunderstorm, or a material like a body, can be described equally by data, in other words it can be read or written. The following prototypes......, Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual examination...

  11. Finite element analysis of plate rolling of duplex-layer steels for long-period fast reactor application

    International Nuclear Information System (INIS)

    Lee, Jungki; Kim, Ji Hyun

    2015-01-01

    With same roll speed and same friction coefficient, curvature is formed on rolled product from FEA result. To reduce this curvature and plastic strain which cause reduction in fabricability, two ways are selected; (i) controlling upper/lower roll speed, and (ii) adjusting upper/lower friction coefficient and contacts. Both results shows it can reduce the curvature and equivalent plastic strain of the plate after the rolling. It can be applied in real plate rolling processing and also the next research for pilgering process for tube and pipe production. The FEA results of equivalent stress and plastic deformation distribution are showed in figure 5. The von-Mises equivalent stress distribution showed that the stress is still concentrated on upper Fe-12Cr-2Si layer, however, it also shows that equivalent plastic strain is distributed uniformly comparing with upper and lower roll speed ratio is 1.0. In high temperature liquid metal environment, there are usually two types of corrosion; one is corrosion by dissolution of alloy elements into liquid metal, and another is corrosion by chemical reaction among impurities in liquid metal and structural alloy. There have been some researches to develop new alloys that can form more dense scale on the surface even in wider impurity range and higher temperature range . M.P Short et al. devised functionally graded composite which is composed of two layers . one is a thin corrosion resistant layer and another is thick structural layer which guarantees mechanical strength, creep rupture strength and shows less irradiation swelling

  12. Are pitch and roll compensations required in all pathologies? A data analysis of 2945 fractions.

    Science.gov (United States)

    Mancosu, Pietro; Reggiori, Giacomo; Gaudino, Anna; Lobefalo, Francesca; Paganini, Lucia; Palumbo, Valentina; Stravato, Antonella; Tomatis, Stefano; Scorsetti, Marta

    2015-01-01

    New linear accelerators can be equipped with a 6D robotic couch, providing two additional rotational motion axes: pitch and roll. These shifts in kilo voltage-cone beam CT (kV-CBCT) image-guided radiotherapy (IGRT) were evaluated over the first 6 months of usage of a 6D robotic couch-top, ranking the treatment sites for which the two compensations are larger for patient set-up. The couch compensations of 2945 fractions for 376 consecutive patients treated on the PerfectPitch™ 6D couch (Varian(®) Medical Systems, Palo Alto, CA) were analysed. Among these patients, 169 were treated for brain, 111 for lung, 54 for liver, 26 for pancreas and 16 for prostate tumours. During the set-up, patient anatomy from planning CT was aligned to kV-CBCT, and 6D movements were executed. Information related to pitch and roll were extracted by proper querying of the Microsoft(®) SQL server (Microsoft Corporation, Redmond, WA) ARIA database (Varian Medical Systems). Mean values and standard deviations were calculated for all sites. Kolmogorov-Smirnov (KS) test was performed. Considering all the data, mean pitch and roll adjustments were -0.10° ± 0.92° and 0.12° ± 0.96°, respectively; mean absolute values for both adjustments were 0.58° ± 0.69° and 0.69° ± 0.72°, respectively. Brain treatments showed the highest mean absolute values for pitch and roll rotations (0.73° ± 0.69° and 0.80° ± 0.78°, respectively); the lowest values of 0.36° ± 0.47° and 0.49° ± 0.58° were found for pancreas. KS test was significant for brain vs liver, pancreas and prostate. Collective corrections (pitch + roll) >0.5°, >1.0° and >2.0° were observed in, respectively, 79.8%, 61.0% and 29.1% for brain and 56.7%, 39.4% and 6.7% for pancreas. Adjustments in all six dimensions, including unconventional pitch and roll rotations, improve the patient set-up in all treatment sites. The greatest improvement was observed for patients with brain tumours. To

  13. Parameters design of the dielectric elastomer spring-roll bending actuator (Conference Presentation)

    Science.gov (United States)

    Li, Jinrong; Liu, Liwu; Liu, Yanju; Leng, Jinsong

    2017-04-01

    Dielectric elastomers are novel soft smart material that could deform sustainably when subjected to external electric field. That makes dielectric elastomers promising materials for actuators. In this paper, a spring-roll actuator that would bend when a high voltage is applied was fabricated based on dielectric elastomer. Using such actuators as active parts, the flexible grippers and inchworm-inspired crawling robots were manufactured, which demonstrated some examples of applications in soft robotics. To guide the parameters design of dielectric elastomer based spring-roll bending actuators, the theoretical model of such actuators was established based on thermodynamic theories. The initial deformation and electrical induced bending angle of actuators were formulated. The failure of actuators was also analyzed considering some typical failure modes like electromechanical instability, electrical breakdown, loss of tension and maximum tolerant stretch. Thus the allowable region of actuators was determined. Then the bending angle-voltage relations and failure voltages of actuators with different parameters, including stretches of the dielectric elastomer film, number of active layers, and dimensions of spring, were investigated. The influences of each parameter on the actuator performances were discussed, providing meaningful guidance to the optical design of the spring-roll bending actuators.

  14. Literature survey on microscopic friction modeling

    NARCIS (Netherlands)

    Hol, J.

    2010-01-01

    To better understand contact and friction conditions, experimental and theoretical studies have been performed in order to take microscopic dependencies into account. Friction is developed on microscopic level by adhesion between contacting asperities, the ploughing effect between asperities and the

  15. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    WINTEC

    Abstract. An asbestos free friction material composite for brake linings is synthesized containing fibrous re- inforcing ... every manufacturer of automotive friction materials uses phenolics as ... The resin binder is a critical compo- nent. The limits ...

  16. Friction tensor concept for textured surfaces

    Indian Academy of Sciences (India)

    Directionality of grinding marks influences the coefficient of friction ... Menezes et al (2006a,b) studied the effect of roughness parameters and grinding angle on ... as coefficient of friction, sliding velocity, normal load, hardness and thermal.

  17. Investigation of subsurface fatigue crack in PEEK shaft under one-point rolling contact by using 2.5D layer observation method

    Directory of Open Access Journals (Sweden)

    KOIKE Hitonobu

    2017-01-01

    Full Text Available Subsurface fatigue cracks under rolling contact area of the PEEK shaft against an alumina bearing’s ball were investigated for application of frictional part in mechanical element in special situations such as chemical environments. In order to explore the flaking process of the PEEK shaft, the rolling contact fatigue tests were carried out by using a one-point radial loading rolling contact machine. The flaking occurred on the rolling track of the PEEK shaft at approximate 4⨉105 fatigue cycles. The subsurface fatigue crack propagation was investigated by using 2.5-Dimension layer observation method. The flaking was caused by the propagations of surface cracks and subsurface shear cracks, and the flaking shape was half-ellipse. Moreover, beach marks as fatigue crack propagation in the flaking were observed.

  18. Robotic Manufacturing of 18-ft (5.5m) Diameter Cryogenic Fuel Tank Dome Assemblies for the NASA Ares I Rocket

    Science.gov (United States)

    Jones, Ronald E.; Carter, Robert W.

    2012-01-01

    The Ares I rocket was the first launch vehicle scheduled for manufacture under the National Aeronautic and Space Administration's Constellation program. A series of full-scale Ares I development articles were constructed on the Robotic Weld Tool at the NASA George C. Marshall Space Flight Center in Huntsville, Alabama. The Robotic Weld Tool is a 100 ton, 7- axis, robotic manufacturing system capable of machining and friction stir welding large-scale space hardware. This paper will focus on the friction stir welding of 18-ft (5.5m) diameter cryogenic fuel tank components; specifically, the liquid hydrogen forward dome and two common bulkhead manufacturing development articles.

  19. The influence of surface topography on the forming friction of automotive aluminum sheet

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, Pamela Ann [Univ. of California, Berkeley, CA (United States). Dept. of Materials Science and Mineral Engineering

    1998-05-01

    Interest in utilizing aluminum alloys in automobiles has increased in recent years as a result of the desire to lower automobile weight and, consequently, increase fuel economy. While aluminum alloy use in cast parts has increased, outer body panel applications are still being investigated. The industry is interested in improving the formability of these sheet alloys by a combination of alloy design and processing. A different avenue of improving the formability of these alloys may be through patterning of the sheet surface. Surface patterns hold the lubricant during the forming process, with a resulting decrease in the sheet-die surface contact. While it has been speculated that an optimum surface pattern would consist of discrete cavities, detailed investigation into the reduction of forming friction by utilizing discrete patterns is lacking. A series of discrete patterns were investigated to determine the dependence of the forming friction of automotive aluminum alloys on pattern lubricant carrying capacity and on material strength. Automotive aluminum alloys used in outer body panel applications were rolled on experimental rolls that had been prepared with a variety of discrete patterns. All patterns for each alloy were characterized before and after testing both optically and, to determine pattern lubricant capacity, using three dimensional laser profilometry. A draw bead simulation (DBS) friction tester was designed and fabricated to determine the forming friction of the patterned sheets. Tensile testing and frictionless DBS testing were performed to ascertain the material properties of each sheet. The most striking result of this work was the inversely linear dependence of forming friction on the lubricant carrying capacity of the discrete patterns.

  20. Methods and Devices used to Measure Friction

    DEFF Research Database (Denmark)

    Jeswiet, Jack; Arentoft, Mogens; Henningsen, Poul

    2004-01-01

    . To gain a good understanding of the mechanisms at the interface and to be able to verify the friction and tribology models that exist, friction sensors are needed. Designing sensors to measure friction-stress in metal working has been pursued by many researchers. This paper surveys methods, which have...... been tried in the past and discusses some of the recent sensor designs, which can now be used to measure Friction in both production situations and for research purposes....

  1. Advances on LuGre friction model

    OpenAIRE

    Fuad, Mohammad; Ikhouane, Fayçal

    2013-01-01

    LuGre friction model is an ordinary differential equation that is widely used in describing the friction phenomenon for mechanical systems. The importance of this model comes from the fact that it captures most of the friction behavior that has been observed including hysteresis. In this paper, we study some aspects related to the hysteresis behavior induced by the LuGre friction model.

  2. Apparatus for measurement of coefficient of friction

    Science.gov (United States)

    Slifka, A. J.; Siegwarth, J. D.; Sparks, L. L.; Chaudhuri, Dilip K.

    1990-01-01

    An apparatus designed to measure the coefficient of friction in certain controlled atmospheres is described. The coefficient of friction observed during high-load tests was nearly constant, with an average value of 0.56. This value is in general agreement with that found in the literature and also with the initial friction coefficient value of 0.67 measured during self-mated friction of 440C steel in an oxygen environment.

  3. A field theoretic model for static friction

    OpenAIRE

    Mahyaeh, I.; Rouhani, S.

    2013-01-01

    We present a field theoretic model for friction, where the friction coefficient between two surfaces may be calculated based on elastic properties of the surfaces. We assume that the geometry of contact surface is not unusual. We verify Amonton's laws to hold that friction force is proportional to the normal load.This model gives the opportunity to calculate the static coefficient of friction for a few cases, and show that it is in agreement with observed values. Furthermore we show that the ...

  4. Robotics Potential Fields

    Directory of Open Access Journals (Sweden)

    Jordi Lucero

    2009-01-01

    Full Text Available This problem was to calculate the path a robot would take to navigate an obstacle field and get to its goal. Three obstacles were given as negative potential fields which the robot avoided, and a goal was given a positive potential field that attracted the robot. The robot decided each step based on its distance, angle, and influence from every object. After each step, the robot recalculated and determined its next step until it reached its goal. The robot's calculations and steps were simulated with Microsoft Excel.

  5. Designing Emotionally Expressive Robots

    DEFF Research Database (Denmark)

    Tsiourti, Christiana; Weiss, Astrid; Wac, Katarzyna

    2017-01-01

    Socially assistive agents, be it virtual avatars or robots, need to engage in social interactions with humans and express their internal emotional states, goals, and desires. In this work, we conducted a comparative study to investigate how humans perceive emotional cues expressed by humanoid...... robots through five communication modalities (face, head, body, voice, locomotion) and examined whether the degree of a robot's human-like embodiment affects this perception. In an online survey, we asked people to identify emotions communicated by Pepper -a highly human-like robot and Hobbit – a robot...... for robots....

  6. Roll forming of eco-friendly stud

    Science.gov (United States)

    Keum, Y. T.; Lee, S. Y.; Lee, T. H.; Sim, J. K.

    2013-12-01

    In order to manufacture an eco-friendly stud, the sheared pattern is designed by the Taguchi method and expanded by the side rolls. The seven geometrical shape of sheared pattern are considered in the structural and thermal analyses to select the best functional one in terms of the durability and fire resistance of dry wall. For optimizing the size of the sheared pattern chosen, the L9 orthogonal array and smaller-the-better characteristics of the Taguchi method are used. As the roll gap causes forming defects when the upper-and-lower roll type is adopted for expanding the sheared pattern, the side roll type is introduced. The stress and strain distributions obtained by the FEM simulation of roll-forming processes are utilized for the design of expanding process. The expanding process by side rolls shortens the length of expanding process and minimizes the cost of dies. Furthermore, the stud manufactured by expanding the sheared pattern of the web is an eco-friend because of the scrapless roll-forming process. In addition, compared to the conventionally roll-formed stud, the material cost is lessened about 13.6% and the weight is lightened about 15.5%.

  7. Pipe Rolling from Continuous Cast Metal

    International Nuclear Information System (INIS)

    Zhordania, I.; Chkhartishvili, I.; Lordkipanidze, J.; Melashvili, Z.; Papava, K.; Khundadze, K.

    2007-01-01

    The approach to manufacturing of high quality pipes as a result of solid and hollow billet rolling from continuous cast metal is shown. Optimal parameters of piercing, temperature of piercing and piercing rolling mill rollers speed have been experimentally established. (author)

  8. Numerical analysis of Swiss roll metamaterials

    International Nuclear Information System (INIS)

    Demetriadou, A; Pendry, J B

    2009-01-01

    A Swiss roll metamaterial is a resonant magnetic medium, with a negative magnetic permeability for a range of frequencies, due to its self-inductance and self-capacitance components. In this paper, we discuss the band structure, S-parameters and effective electromagnetic parameters of Swiss roll metamaterials, with both analytical and numerical results, which show an exceptional convergence.

  9. Efficient Circulation of Railway Rolling Stock

    NARCIS (Netherlands)

    A. Alfieri (Arianna); R. Groot (Rutger); L.G. Kroon (Leo); A. Schrijver (Lex)

    2002-01-01

    textabstractRailway rolling stock (locomotives, carriages, and train units) is one of the most significant cost sources for operatorsof passenger trains, both public and private. Rolling stock costsare due to material acquisition, power supply, and material maintenance. The efficient circulation of

  10. Advanced mechanics in robotic systems

    CERN Document Server

    Nava Rodríguez, Nestor Eduardo

    2011-01-01

    Illustrates original and ambitious mechanical designs and techniques for the development of new robot prototypes Includes numerous figures, tables and flow charts Discusses relevant applications in robotics fields such as humanoid robots, robotic hands, mobile robots, parallel manipulators and human-centred robots

  11. Friction and dissipative phenomena in quantum mechanics

    International Nuclear Information System (INIS)

    Kostin, M.D.

    1975-01-01

    Frictional and dissipative terms of the Schroedinger equation are studied. A proof is given showing that the frictional term of the Schroedinger--Langevin equation causes the quantum system to lose energy. General expressions are derived for the frictional term of the Schroedinger equation. (U.S.)

  12. Adaptive friction compensation: a globally stable approach

    NARCIS (Netherlands)

    Verbert, K.A.; Tóth, R.; Babuska, R.

    2016-01-01

    In this paper, an adaptive friction compensation scheme is proposed. The friction force is computed as a timevarying friction coefficient multiplied by the sign of the velocity and an on-line update law is designed to estimate this coefficient based on the actual position and velocity errors.

  13. Multiscale friction modeling for sheet metal forming

    NARCIS (Netherlands)

    Hol, J.; Cid Alfaro, M.V.; de Rooij, Matthias B.; Meinders, Vincent T.; Felder, Eric; Montmitonnet, Pierre

    2010-01-01

    The most often used friction model for sheet metal forming simulations is the relative simple Coulomb friction model. This paper presents a more advanced friction model for large scale forming simulations based on the surface change on the micro-scale. The surface texture of a material changes when

  14. A thermodynamic model of sliding friction

    Directory of Open Access Journals (Sweden)

    Lasse Makkonen

    2012-03-01

    Full Text Available A first principles thermodynamic model of sliding friction is derived. The model predictions are in agreement with the observed friction laws both in macro- and nanoscale. When applied to calculating the friction coefficient the model provides a quantitative agreement with recent atomic force microscopy measurements on a number of materials.

  15. Asbestos free friction composition for brake linings

    Indian Academy of Sciences (India)

    An asbestos free friction material composite for brake linings is synthesized containing fibrous reinforcing constituents, friction imparting and controlling additives, elastomeric additives, fire retarding components and a thermosetting resin. The composite shows exemplary friction characteristics and has great resistance to ...

  16. Frictional properties of confined polymers

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N; Persson, Bo N J

    2008-01-01

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively i...

  17. Improved Coulomb-Friction Damper

    Science.gov (United States)

    Campbell, G. E.

    1985-01-01

    Equal damping provided on forward and reverse strokes. Improved damper has springs and wedge rings symmetrically placed on both ends of piston wedge, so friction force same in both directions of travel. Unlike conventional automotive shock absorbers, they resemble on outside, both versions require no viscous liquid and operate over wide temperature range.

  18. Deformation During Friction Stir Welding

    Science.gov (United States)

    White, Henry J.

    2002-01-01

    Friction Stir Welding (FSW) is a solid state welding process that exhibits characteristics similar to traditional metal cutting processes. The plastic deformation that occurs during friction stir welding is due to the superposition of three flow fields: a primary rotation of a radially symmetric solid plug of metal surrounding the pin tool, a secondary uniform translation, and a tertiary ring vortex flow (smoke rings) surrounding the tool. If the metal sticks to the tool, the plug surface extends down into the metal from the outer edge of the tool shoulder, decreases in diameter like a funnel, and closes up beneath the pin. Since its invention, ten years have gone by and still very little is known about the physics of the friction stir welding process. In this experiment, an H13 steel weld tool (shoulder diameter, 0.797 in; pin diameter, 0.312 in; and pin length, 0.2506 in) was used to weld three 0.255 in thick plates. The deformation behavior during friction stir welding was investigated by metallographically preparing a plan view sections of the weldment and taking Vickers hardness test in the key-hole region.

  19. Information frictions and monetary policy

    Czech Academy of Sciences Publication Activity Database

    Matějka, Filip

    2012-01-01

    Roč. 6, č. 1 (2012), s. 7-24 ISSN 1802-792X Institutional support: RVO:67985998 Keywords : nominal rigidity * information frictions * monetary economics Subject RIV: AH - Economics http://www.vsfs.cz/periodika/acta-2012-01.pdf

  20. Constant-roll (quasi-)linear inflation

    Science.gov (United States)

    Karam, A.; Marzola, L.; Pappas, T.; Racioppi, A.; Tamvakis, K.

    2018-05-01

    In constant-roll inflation, the scalar field that drives the accelerated expansion of the Universe is rolling down its potential at a constant rate. Within this framework, we highlight the relations between the Hubble slow-roll parameters and the potential ones, studying in detail the case of a single-field Coleman-Weinberg model characterised by a non-minimal coupling of the inflaton to gravity. With respect to the exact constant-roll predictions, we find that assuming an approximate slow-roll behaviour yields a difference of Δ r = 0.001 in the tensor-to-scalar ratio prediction. Such a discrepancy is in principle testable by future satellite missions. As for the scalar spectral index ns, we find that the existing 2-σ bound constrains the value of the non-minimal coupling to ξphi ~ 0.29–0.31 in the model under consideration.

  1. Analytical method for establishing indentation rolling resistance

    Directory of Open Access Journals (Sweden)

    Gładysiewicz Lech

    2018-01-01

    Full Text Available Belt conveyors are highly reliable machines able to work in special operating conditions. Harsh environment, long distance of transporting and great mass of transported martials are cause of high energy usage. That is why research in the field of belt conveyor transportation nowadays focuses on reducing the power consumption without lowering their efficiency. In this paper, previous methods for testing rolling resistance are described, and new method designed by authors was presented. New method of testing rolling resistance is quite simple and inexpensive. Moreover it allows to conduct the experimental tests of the impact of different parameters on the value of indentation rolling resistance such as core design, cover thickness, ambient temperature, idler travel frequency, or load value as well. Finally results of tests of relationship between rolling resistance and idler travel frequency and between rolling resistance and idler travel speed was presented.

  2. Analytical method for establishing indentation rolling resistance

    Science.gov (United States)

    Gładysiewicz, Lech; Konieczna, Martyna

    2018-01-01

    Belt conveyors are highly reliable machines able to work in special operating conditions. Harsh environment, long distance of transporting and great mass of transported martials are cause of high energy usage. That is why research in the field of belt conveyor transportation nowadays focuses on reducing the power consumption without lowering their efficiency. In this paper, previous methods for testing rolling resistance are described, and new method designed by authors was presented. New method of testing rolling resistance is quite simple and inexpensive. Moreover it allows to conduct the experimental tests of the impact of different parameters on the value of indentation rolling resistance such as core design, cover thickness, ambient temperature, idler travel frequency, or load value as well. Finally results of tests of relationship between rolling resistance and idler travel frequency and between rolling resistance and idler travel speed was presented.

  3. New perspectives on constant-roll inflation

    Science.gov (United States)

    Cicciarella, Francesco; Mabillard, Joel; Pieroni, Mauro

    2018-01-01

    We study constant-roll inflation using the β-function formalism. We show that the constant rate of the inflaton roll is translated into a first order differential equation for the β-function which can be solved easily. The solutions to this equation correspond to the usual constant-roll models. We then construct, by perturbing these exact solutions, more general classes of models that satisfy the constant-roll equation asymptotically. In the case of an asymptotic power law solution, these corrections naturally provide an end to the inflationary phase. Interestingly, while from a theoretical point of view (in particular in terms of the holographic interpretation) these models are intrinsically different from standard slow-roll inflation, they may have phenomenological predictions in good agreement with present cosmological data.

  4. Upscaling of polymer solar cell fabrication using full roll-to-roll processing

    DEFF Research Database (Denmark)

    Krebs, Frederik C; Tromholt, Thomas; Jørgensen, Mikkel

    2010-01-01

    factors (excluding bus bars) of 50, 67 and 75% respectively. In addition modules with lengths of 6, 10, 20, 22.5 and 25 cm were explored. The devices were prepared by full roll-to-roll solution processing in a web width of 305 mm and roll lengths of up to 200 m. The devices were encapsulated...... with a barrier material in a full roll-to-roll process using standard adhesives giving the devices excellent stability during storage and operation. The total area of processed polymer solar cell was around 60 m2 per run. The solar cells were characterised using a roll-to-roll system comprising a solar simulator...... to the cost for electricity using existing technologies the levelized cost of electricity (LCOE) is expected to be significantly higher than the existing technologies due to the inferior operational lifetime. The presented devices are thus competitive for consumer electronics but ill-suited for on...

  5. Robotics_MobileRobot Navigation, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Robots and rovers exploring planets need to autonomously navigate to specified locations. Advanced Scientific Concepts, Inc. (ASC) and the University of Minnesota...

  6. Robots Social Embodiment in Autonomous Mobile Robotics

    Directory of Open Access Journals (Sweden)

    Brian Duffy

    2008-11-01

    Full Text Available This work aims at demonstrating the inherent advantages of embracing a strong notion of social embodiment in designing a real-world robot control architecture with explicit ?intelligent? social behaviour between a collective of robots. It develops the current thinking on embodiment beyond the physical by demonstrating the importance of social embodiment. A social framework develops the fundamental social attributes found when more than one robot co-inhabit a physical space. The social metaphors of identity, character, stereotypes and roles are presented and implemented within a real-world social robot paradigm in order to facilitate the realisation of explicit social goals.

  7. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    Energy Technology Data Exchange (ETDEWEB)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R. [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States); Gibeling, J.C., E-mail: jcgibeling@ucdavis.edu [Department of Chemical Engineering and Materials Science, University of California, One Shields Ave., Davis, CA 95616 (United States)

    2010-10-15

    Research highlights: {yields} A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. {yields} The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. {yields} Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and

  8. The influence of post-processing on creep and microstructure of rolled Cu-8Cr-4Nb

    International Nuclear Information System (INIS)

    Walley, J.L.; Heelan, J.L.; Vettraino, L.G.; Groza, J.R.; Gibeling, J.C.

    2010-01-01

    Research highlights: → A simulated-life heat treatment anneal of 24 h at 773 K reduced the steady-state creep rate and increased the creep life of a rolled powder metallurgy Cu-8Cr-4Nb alloy. → The primary microstructural difference between the rolled form and the annealed form of Cu-8Cr-4Nb is the development of annealing twins during heat treatment causing a decrease in the intensity of the texture. → Friction stir welding of rolled Cu-8Cr-4Nb negatively affected creep ductility, thereby decreasing creep life at the temperature tested. Strain localization in the soft heat-affected zone of the weld is hypothesized to be the cause of the decreased creep ductility. - Abstract: Previous work has shown that rolling of an extruded Cu-8Cr-4Nb (GRCop-84) alloy results in higher steady-state creep rates over a range of stresses, leading to concern that other post-processing methods could have substantial deleterious effects on creep properties. To explore that possibility, constant-stress creep tests were conducted at 773 K on rolled GRCop-84 after it was subjected to either friction stir welding (FSW) or a 24 h 1073 K simulated-life heat treatment. The FSW had no measurable effect on the creep rate of the rolled material, but did have detrimental effects on the creep ductility caused by softening, and thus strain localization, in the heat-affected zone of the weld. The simulated-life heat treatment decreased the steady-state creep rate by approximately 45% as compared to the rolled material, leading to longer creep life at a particular applied stress. Electron backscatter diffraction methods were used to compare the microstructural features of extruded, rolled and annealed material forms. It was determined that the rolling procedure decreased the grain size, and decreased the intensity of the texture as compared to the extruded form. The simulated-life heat treatment allowed for the substantial development of twins along with minor grain growth, and a substantial

  9. Robotic tool positioning process using a multi-line off-axis laser triangulation sensor

    Science.gov (United States)

    Pinto, T. C.; Matos, G.

    2018-03-01

    Proper positioning of a friction stir welding head for pin insertion, driven by a closed chain robot, is important to ensure quality repair of cracks. A multi-line off-axis laser triangulation sensor was designed to be integrated to the robot, allowing relative measurements of the surface to be repaired. This work describes the sensor characteristics, its evaluation and the measurement process for tool positioning to a surface point of interest. The developed process uses a point of interest image and a measured point cloud to define the translation and rotation for tool positioning. Sensor evaluation and tests are described. Keywords: laser triangulation, 3D measurement, tool positioning, robotics.

  10. Artificial Potential Field Approach to Path Tracking for a Non-Holonomic Mobile Robot

    DEFF Research Database (Denmark)

    Sørensen, M.J.

    2003-01-01

    This paper introduces a novel path tracking controller for an over-actuated robotic vehicle moving in an agricultural field. The vehicle itself is a four wheel steered, four wheel driven vehicle subject to the two non-holonomic constraints of free rolling and non-slipping wheels. A dynamic model...

  11. Springer handbook of robotics

    CERN Document Server

    Khatib, Oussama

    2016-01-01

    The second edition of this handbook provides a state-of-the-art cover view on the various aspects in the rapidly developing field of robotics. Reaching for the human frontier, robotics is vigorously engaged in the growing challenges of new emerging domains. Interacting, exploring, and working with humans, the new generation of robots will increasingly touch people and their lives. The credible prospect of practical robots among humans is the result of the scientific endeavour of a half a century of robotic developments that established robotics as a modern scientific discipline. The ongoing vibrant expansion and strong growth of the field during the last decade has fueled this second edition of the Springer Handbook of Robotics. The first edition of the handbook soon became a landmark in robotics publishing and won the American Association of Publishers PROSE Award for Excellence in Physical Sciences & Mathematics as well as the organization’s Award for Engineering & Technology. The second edition o...

  12. Project ROBOTICS 2008

    DEFF Research Database (Denmark)

    Conrad, Finn

    Mathematical modelling of Alto Robot, direct- and inverse kinematic transformation,simulation and path control applying MATLAB/SIMULINK.......Mathematical modelling of Alto Robot, direct- and inverse kinematic transformation,simulation and path control applying MATLAB/SIMULINK....

  13. Project Tasks in Robotics

    DEFF Research Database (Denmark)

    Sørensen, Torben; Hansen, Poul Erik

    1998-01-01

    Description of the compulsary project tasks to be carried out as a part of DTU course 72238 Robotics......Description of the compulsary project tasks to be carried out as a part of DTU course 72238 Robotics...

  14. CMS cavern inspection robot

    CERN Document Server

    Ibrahim, Ibrahim

    2017-01-01

    Robots which are immune to the CMS cavern environment, wirelessly controlled: -One actuated by smart materials (Ionic Polymer-Metal Composites and Macro Fiber Composites) -One regular brushed DC rover -One servo-driven rover -Stair-climbing robot

  15. Pressure and Friction Injuries in Primary Care.

    Science.gov (United States)

    Phillips, Shawn; Seiverling, Elizabeth; Silvis, Matthew

    2015-12-01

    Pressure and friction injuries are common throughout the lifespan. A detailed history of the onset and progression of friction and pressure injuries is key to aiding clinicians in determining the underlying mechanism behind the development of the injury. Modifying or removing the forces that are creating pressure or friction is the key to both prevention and healing of these injuries. Proper care of pressure and friction injuries to the skin is important to prevent the development of infection. Patient education on positioning and ergonomics can help to prevent recurrence of pressure and friction injuries. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Friction, Free Axes of Rotation and Entropy

    Directory of Open Access Journals (Sweden)

    Alexander Kazachkov

    2017-03-01

    Full Text Available Friction forces acting on rotators may promote their alignment and therefore eliminate degrees of freedom in their movement. The alignment of rotators by friction force was shown by experiments performed with different spinners, demonstrating how friction generates negentropy in a system of rotators. A gas of rigid rotators influenced by friction force is considered. The orientational negentropy generated by a friction force was estimated with the Sackur-Tetrode equation. The minimal change in total entropy of a system of rotators, corresponding to their eventual alignment, decreases with temperature. The reported effect may be of primary importance for the phase equilibrium and motion of ubiquitous colloidal and granular systems.

  17. RHOBOT: Radiation hardened robotics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, P.C.; Posey, L.D. [Sandia National Labs., Albuquerque, NM (United States)

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program.

  18. Micro robot bible

    International Nuclear Information System (INIS)

    Yoon, Jin Yeong

    2000-08-01

    This book deals with micro robot, which tells of summary of robots like entertainment robots and definition of robots, introduction of micro mouse about history, composition and rules, summary of micro controller with its history, appearance and composition, introduction of stepping motor about types, structure, basic characteristics, and driving ways, summary of sensor section, power, understanding of 80C196KC micro controller, basic driving program searching a maze algorithm, smooth turn and making of tracer line.

  19. RHOBOT: Radiation hardened robotics

    International Nuclear Information System (INIS)

    Bennett, P.C.; Posey, L.D.

    1997-10-01

    A survey of robotic applications in radioactive environments has been conducted, and analysis of robotic system components and their response to the varying types and strengths of radiation has been completed. Two specific robotic systems for accident recovery and nuclear fuel movement have been analyzed in detail for radiation hardness. Finally, a general design approach for radiation-hardened robotics systems has been developed and is presented. This report completes this project which was funded under the Laboratory Directed Research and Development program

  20. Two Legged Walking Robot

    OpenAIRE

    Kraus, V.

    2015-01-01

    The aim of this work is to construct a two-legged wirelessly controlled walking robot. This paper describes the construction of the robot, its control electronics, and the solution of the wireless control. The article also includes a description of the application to control the robot. The control electronics of the walking robot are built using the development kit Arduino Mega, which is enhanced with WiFi module allowing the wireless control, a set of ultrasonic sensors for detecting obstacl...

  1. Micro robot bible

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Jin Yeong

    2000-08-15

    This book deals with micro robot, which tells of summary of robots like entertainment robots and definition of robots, introduction of micro mouse about history, composition and rules, summary of micro controller with its history, appearance and composition, introduction of stepping motor about types, structure, basic characteristics, and driving ways, summary of sensor section, power, understanding of 80C196KC micro controller, basic driving program searching a maze algorithm, smooth turn and making of tracer line.

  2. Robots at Work

    OpenAIRE

    Graetz, Georg; Michaels, Guy

    2015-01-01

    Despite ubiquitous discussions of robots' potential impact, there is almost no systematic empirical evidence on their economic effects. In this paper we analyze for the first time the economic impact of industrial robots, using new data on a panel of industries in 17 countries from 1993-2007. We find that industrial robots increased both labor productivity and value added. Our panel identification is robust to numerous controls, and we find similar results instrumenting increased robot use wi...

  3. Robots in the Roses

    OpenAIRE

    2014-01-01

    2014-04 Robots in the Roses A CRUSER Sponsored Event. The 4th Annual Robots in the Roses provides a venue for Faculty & NPS Students to showcase unmanned systems research (current or completed) and recruit NPS Students to join in researching on your project. Posters, robots, vehicles, videos, and even just plain humans welcome! Families are welcome to attend Robots in the Roses as we'll have a STEM activity for children to participate in.

  4. Modular robot

    International Nuclear Information System (INIS)

    Ferrante, T.A.

    1997-01-01

    A modular robot may comprise a main body having a structure defined by a plurality of stackable modules. The stackable modules may comprise a manifold, a valve module, and a control module. The manifold may comprise a top surface and a bottom surface having a plurality of fluid passages contained therein, at least one of the plurality of fluid passages terminating in a valve port located on the bottom surface of the manifold. The valve module is removably connected to the manifold and selectively fluidically connects the plurality of fluid passages contained in the manifold to a supply of pressurized fluid and to a vent. The control module is removably connected to the valve module and actuates the valve module to selectively control a flow of pressurized fluid through different ones of the plurality of fluid passages in the manifold. The manifold, valve module, and control module are mounted together in a sandwich-like manner and comprise a main body. A plurality of leg assemblies are removably connected to the main body and are removably fluidically connected to the fluid passages in the manifold so that each of the leg assemblies can be selectively actuated by the flow of pressurized fluid in different ones of the plurality of fluid passages in the manifold. 12 figs

  5. Robot 2015 : Second Iberian Robotics Conference : Advances in Robotics

    CERN Document Server

    Moreira, António; Lima, Pedro; Montano, Luis; Muñoz-Martinez, Victor

    2016-01-01

    This book contains a selection of papers accepted for presentation and discussion at ROBOT 2015: Second Iberian Robotics Conference, held in Lisbon, Portugal, November 19th-21th, 2015. ROBOT 2015 is part of a series of conferences that are a joint organization of SPR – “Sociedade Portuguesa de Robótica/ Portuguese Society for Robotics”, SEIDROB – Sociedad Española para la Investigación y Desarrollo de la Robótica/ Spanish Society for Research and Development in Robotics and CEA-GTRob – Grupo Temático de Robótica/ Robotics Thematic Group. The conference organization had also the collaboration of several universities and research institutes, including: University of Minho, University of Porto, University of Lisbon, Polytechnic Institute of Porto, University of Aveiro, University of Zaragoza, University of Malaga, LIACC, INESC-TEC and LARSyS. Robot 2015 was focussed on the Robotics scientific and technological activities in the Iberian Peninsula, although open to research and delegates from other...

  6. 3D analysis of cold rolling using a constitutive model for interface friction

    DEFF Research Database (Denmark)

    Richelsen, Ann Bettina; Tvergaard, Viggo

    2004-01-01

    as no slip is accounted for. Finite strain elasto-plasticity is applied for the plate material, using mostly isotropic hardening or in a few cases kinematic hardening to represent the effect of a rounded vertex on the yield surface. In addition, for a given plate thickness and degree of reduction the effect...

  7. Building a Better Robot

    Science.gov (United States)

    Navah, Jan

    2012-01-01

    Kids love to build robots, letting their imaginations run wild with thoughts of what they might look like and what they could be programmed to do. Yet when students use cereal boxes and found objects to make robots, often the projects look too similar and tend to fall apart. This alternative allows students to "build" robots in a different way,…

  8. Open middleware for robotics

    CSIR Research Space (South Africa)

    Namoshe, M

    2008-12-01

    Full Text Available and their technologies within the field of multi-robot systems to ease the difficulty of realizing robot applications. And lastly, an example of algorithm development for multi-robot co-operation using one of the discussed software architecture is presented...

  9. Learning robotics using Python

    CERN Document Server

    Joseph, Lentin

    2015-01-01

    If you are an engineer, a researcher, or a hobbyist, and you are interested in robotics and want to build your own robot, this book is for you. Readers are assumed to be new to robotics but should have experience with Python.

  10. Robots de servicio

    Directory of Open Access Journals (Sweden)

    Rafael Aracil

    2008-04-01

    Full Text Available Resumen: El término Robots de Servicio apareció a finales de los años 80 como una necesidad de desarrollar máquinas y sistemas capaces de trabajar en entornos diferentes a los fabriles. Los Robots de Servicio tenían que poder trabajar en entornos noestructurados, en condiciones ambientales cambiantes y con una estrecha interacción con los humanos. En 1995 fue creado por la IEEE Robotics and Automation Society, el Technical Committee on Service Robots, y este comité definió en el año 2000 las áreas de aplicación de los Robots de Servicios, que se pueden dividir en dos grandes grupos: 1 sectores productivos no manufactureros tales como edificación, agricultura, naval, minería, medicina, etc. y 2 sectores de servicios propiamente dichos: asistencia personal, limpieza, vigilancia, educación, entretenimiento, etc. En este trabajo se hace una breve revisión de los principales conceptos y aplicaciones de los robots de servicio. Palabras clave: Robots de servicio, robots autónomos, robots de exteriores, robots de educación y entretenimiento, robots caminantes y escaladores, robots humanoides

  11. Beyond Speculative Robot Ethics

    NARCIS (Netherlands)

    Smits, M.; Van der Plas, A.

    2010-01-01

    In this article we develop a dialogue model for robot technology experts and designated users to discuss visions on the future of robotics in long-term care. Our vision assessment study aims for more distinguished and more informed visions on future robots. Surprisingly, our experiment also lead to

  12. Robotic hand and fingers

    Science.gov (United States)

    Salisbury, Curt Michael; Dullea, Kevin J.

    2017-06-06

    Technologies pertaining to a robotic hand are described herein. The robotic hand includes one or more fingers releasably attached to a robotic hand frame. The fingers can abduct and adduct as well as flex and tense. The fingers are releasably attached to the frame by magnets that allow for the fingers to detach from the frame when excess force is applied to the fingers.

  13. Inflation with a constant rate of roll

    International Nuclear Information System (INIS)

    Motohashi, Hayato; Starobinsky, Alexei A.; Yokoyama, Jun'ichi

    2015-01-01

    We consider an inflationary scenario where the rate of inflaton roll defined by ·· φ/H φ-dot remains constant. The rate of roll is small for slow-roll inflation, while a generic rate of roll leads to the interesting case of 'constant-roll' inflation. We find a general exact solution for the inflaton potential required for such inflaton behaviour. In this model, due to non-slow evolution of background, the would-be decaying mode of linear scalar (curvature) perturbations may not be neglected. It can even grow for some values of the model parameter, while the other mode always remains constant. However, this always occurs for unstable solutions which are not attractors for the given potential. The most interesting particular cases of constant-roll inflation remaining viable with the most recent observational data are quadratic hilltop inflation (with cutoff) and natural inflation (with an additional negative cosmological constant). In these cases even-order slow-roll parameters approach non-negligible constants while the odd ones are asymptotically vanishing in the quasi-de Sitter regime

  14. Design and analysis of roll cage

    Science.gov (United States)

    Angadi, Gurusangappa; Chetan, S.

    2018-04-01

    Wildlife fire fighting vehicles are used to extinguish fires in forests, in this process vehicles face falling objects like rocks, tree branches and other objects. Also due to uneven conditions of the terrain like cliff edges, uneven surfaces etc. makes the vehicle to roll over and these can cause injuries to both the driver and the operator. Roll over of a vehicle is a common incident which makes fatal injuries to the operator and also stands next to the crash accidents. In order to reduce the injury level and continuous roll over of the vehicle it is necessary to equip suitable roll cage according to standards of vehicle. In this present work roll cage for pump operator in wildfire fighting vehicle is designed and analysis is carried out in computer simulated environment when seating position of operator seated outside of the cabin. According to NFPA 1906 standards wildlife fire apparatus, Design and Test procedures that are carried out in Hyperworks maintaining SAE J1194.1983 standards. G load case, roof crush analysis and pendulum impact analysis tests are carried out on roll cage to ensure the saftey of design. These load cases are considerd to satisfy the situation faced in forest terrain. In these test procedures roll cage is analysed for stresses and deformation in various load cases. After recording results these are compared with standards mentioned in SAE J1194.1983.

  15. Inflationary dynamics with a smooth slow-roll to constant-roll era transition

    Energy Technology Data Exchange (ETDEWEB)

    Odintsov, S.D. [ICREA, Passeig Luis Companys, 23, 08010 Barcelona (Spain); Oikonomou, V.K., E-mail: odintsov@ieec.uab.es, E-mail: v.k.oikonomou1979@gmail.com [Laboratory for Theoretical Cosmology, Tomsk State University of Control Systems and Radioelectronics (TUSUR), Lenin Avenue 40, 634050 Tomsk (Russian Federation)

    2017-04-01

    In this paper we investigate the implications of having a varying second slow-roll index on the canonical scalar field inflationary dynamics. We shall be interested in cases that the second slow-roll can take small values and correspondingly large values, for limiting cases of the function that quantifies the variation of the second slow-roll index. As we demonstrate, this can naturally introduce a smooth transition between slow-roll and constant-roll eras. We discuss the theoretical implications of the mechanism we introduce and we use various illustrative examples in order to better understand the new features that the varying second slow-roll index introduces. In the examples we will present, the second slow-roll index has exponential dependence on the scalar field, and in one of these cases, the slow-roll era corresponds to a type of α-attractor inflation. Finally, we briefly discuss how the combination of slow-roll and constant-roll may lead to non-Gaussianities in the primordial perturbations.

  16. An Exploratory Investigation into the Effects of Adaptation in Child-Robot Interaction

    Science.gov (United States)

    Salter, Tamie; Michaud, François; Létourneau, Dominic

    The work presented in this paper describes an exploratory investigation into the potential effects of a robot exhibiting an adaptive behaviour in reaction to a child’s interaction. In our laboratory we develop robotic devices for a diverse range of children that differ in age, gender and ability, which includes children that are diagnosed with cognitive difficulties. As all children vary in their personalities and styles of interaction, it would follow that adaptation could bring many benefits. In this abstract we give our initial examination of a series of trials which explore the effects of a fully autonomous rolling robot exhibiting adaptation (through changes in motion and sound) compared to it exhibiting pre-programmed behaviours. We investigate sensor readings on-board the robot that record the level of ‘interaction’ that the robot receives when a child plays with it and also we discuss the results from analysing video footage looking at the social aspect of the trial.

  17. Jumping robots: a biomimetic solution to locomotion across rough terrain.

    Science.gov (United States)

    Armour, Rhodri; Paskins, Keith; Bowyer, Adrian; Vincent, Julian; Megill, William; Bomphrey, Richard

    2007-09-01

    This paper introduces jumping robots as a means to traverse rough terrain; such terrain can pose problems for traditional wheeled, tracked and legged designs. The diversity of jumping mechanisms found in nature is explored to support the theory that jumping is a desirable ability for a robot locomotion system to incorporate, and then the size-related constraints are determined from first principles. A series of existing jumping robots are presented and their performance summarized. The authors present two new biologically inspired jumping robots, Jollbot and Glumper, both of which incorporate additional locomotion techniques of rolling and gliding respectively. Jollbot consists of metal hoop springs forming a 300 mm diameter sphere, and when jumping it raises its centre of gravity by 0.22 m and clears a height of 0.18 m. Glumper is of octahedral shape, with four 'legs' that each comprise two 500 mm lengths of CFRP tube articulating around torsion spring 'knees'. It is able to raise its centre of gravity by 1.60 m and clears a height of 1.17 m. The jumping performance of the jumping robot designs presented is discussed and compared against some specialized jumping animals. Specific power output is thought to be the performance-limiting factor for a jumping robot, which requires the maximization of the amount of energy that can be stored together with a minimization of mass. It is demonstrated that this can be achieved through optimization and careful materials selection.

  18. A technique for the determination of center of gravity and rolling resistance for tilt-seat wheelchairs.

    Science.gov (United States)

    Lemaire, E D; Lamontagne, M; Barclay, H W; John, T; Martel, G

    1991-01-01

    A balance platform setup was defined for use in the determination of the center of gravity in the sagittal plane for a wheelchair and patient. Using the center of gravity information, measurements from the wheelchair and patient (weight, tire coefficients of friction), and various assumptions (constant speed, level-concrete surface, patient-wheelchair system is a rigid body), a method for estimating the rolling resistance for a wheelchair was outlined. The center of gravity and rolling resistance techniques were validated against criterion values (center of gravity error = 1 percent, rolling resistance root mean square error = 0.33 N, rolling resistance Pearson correlation coefficient = 0.995). Consistent results were also obtained from a test dummy and five subjects. Once the center of gravity is known, it is possible to evaluate the stability of a wheelchair (in terms of tipping over) and the interaction between the level of stability and rolling resistance. These quantitative measures are expected to be of use in the setup of wheelchairs with a variable seat angle and variable wheelbase length or when making comparisons between different wheelchairs.

  19. Look! It's Rock'n'roll!

    DEFF Research Database (Denmark)

    Lindelof, Anja

    2007-01-01

    , and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- Anja Mølle Lindelof. (2007). Look! it's rock'n'roll! how television participated in shaping the visual genre conventions of popular music...... to personal names, capitalization, and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- Anja Mølle Lindelof. "Look! It's Rock'n'roll! How television participated in shaping the visual genre....... Pay special attention to personal names, capitalization, and dates. Consult your library or click here for more information on citing sources. -------------------------------------------------------------------------------- TY - JOUR T1 - Look! It's Rock'n'roll! How television participated in shaping...

  20. Replication of nanopits and nanopillars by roll-to-roll extrusion coating using a structured cooling roll

    DEFF Research Database (Denmark)

    Murthy, Swathi; Pranov, Henrik; Pedersen, Henrik Chresten

    2016-01-01

    This paper investigates a novel, very high throughput, roll-to-roll (R2R) process for nanostructuring of polymer foils, called R2R extrusion coating. It has the potential to accelerate the integration of nanostructured materials in consumer products for a variety of applications, including optical....../height of 100 nm. The best replication was achieved in polypropylene, by running at high roller line-speed of 60 m/min, and high cooling roller temperature of 70°C. Replication in other common polymers like polyethylene and polystyrene was not possible for the parameter range used for the investigation......., technical, and functional surfaces and devices. In roll-to-roll extrusion coating, a molten polymer film is extruded through a flat die forming a melt curtain, and then laminated onto a carrier foil. The lamination occurs as the melt curtain is pressed between a cooling roller and a counter roller...

  1. Closed-Loop Dynamic Parameter Identification of Robot Manipulators Using Modified Fourier Series

    Directory of Open Access Journals (Sweden)

    Wenxiang Wu

    2012-05-01

    Full Text Available This paper concerns the problem of dynamic parameter identification of robot manipulators and proposes a closed-loop identification procedure using modified Fourier series (MFS as exciting trajectories. First, a static continuous friction model is involved to model joint friction for realizable friction compensation in controller design. Second, MFS satisfying the boundary conditions are firstly designed as periodic exciting trajectories. To minimize the sensitivity to measurement noise, the coefficients of MFS are optimized according to the condition number criterion. Moreover, to obtain accurate parameter estimates, the maximum likelihood estimation (MLE method considering the influence of measurement noise is adopted. The proposed identification procedure has been implemented on the first three axes of the QIANJIANG-I 6-DOF robot manipulator. Experiment results verify the effectiveness of the proposed approach, and comparison between identification using MFS and that using finite Fourier series (FFS reveals that the proposed method achieves better identification accuracy.

  2. A Study on the Optimal Conditions of friction Welding for JLF and STS304 Using AE Technique

    International Nuclear Information System (INIS)

    Yoon, Han Ki; Lee, Sang Pil; Kong, Yu Sik; Lee, Jin Kyung

    2003-01-01

    Japanese low activation terrific steel(JLF) is a good material for the parts of heat exchanger such as blanket and diverter. At first, JLF was developed as a candidate for structural materials in nuclear fusion applications. However, the development of the jointing technique of JLF steel to other materials is important for wide applications of this material to the industry fields. Recently the jointing technologies including diffusion bonding, brazing, roll bonding, explosive bonding and hot iso-static pressing have been studied for the heterogeneous materials of JLF-1 steel(Fe-9Cr-2W-V-Ta) and stainless steel(STS304). Friction welding is one of the most popular welding methods for two different kinds of materials. In this paper, the JLF-1 steel was jointed to SIS304 by friction welding method and the optimal conditions of the friction welding discussed. Acoustic emission was used as a nondestructive technique to evaluate the weld quality in processing

  3. Influence of the microstructural changes and induced residual stresses on tensile properties of wrought magnesium alloy friction stir welds

    International Nuclear Information System (INIS)

    Commin, Loreleï; Dumont, Myriam; Rotinat, René; Pierron, Fabrice; Masse, Jean-Eric; Barrallier, Laurent

    2012-01-01

    Highlights: ► Study of AZ31 FSW mechanical behaviour. ► Early yielding occurs in the TMAZ, the nugget and base metal zones undergo almost no plastic strains. ► Texture gradient in the TMAZ localises the deformations in this area. ► Residual stresses have a major influence in FSW mechanical behaviour. - Abstract: Friction stir welding induces a microstructural evolution and residual stresses that will influence the resulting mechanical properties. Friction stir welds produced from magnesium alloy hot rolled plates were studied. Electron back scattered diffraction was used to determine the texture evolution, residual stresses were analysed using X ray diffraction and tensile tests coupled with speckle interferometry were performed. The residual stresses induced during friction stir welding present a major influence on the final mechanical properties.

  4. Intelligent tires for identifying coefficient of friction of tire/road contact surfaces using three-axis accelerometer

    International Nuclear Information System (INIS)

    Matsuzaki, Ryosuke; Kamai, Kazuto; Seki, Ryosuke

    2015-01-01

    Intelligent tires equipped with sensors as well as the monitoring of the tire/road contact conditions are in demand for improving vehicle control and safety. With the aim of identifying the coefficient of friction of tire/road contact surfaces during driving, including during cornering, we develop an identification scheme for the coefficient of friction that involves estimation of the slip angle and applied force by using a single lightweight three-axis accelerometer attached on the inner surface of the tire. To validate the developed scheme, we conduct tire-rolling tests using an accelerometer-equipped tire with various slip angles on various types of road surfaces, including dry and wet surfaces. The results of these tests confirm that the estimated slip angle and applied force are reasonable. Furthermore, the identified coefficient of friction by the developed scheme agreed with that measured by standardized tests. (paper)

  5. Flocking algorithm for autonomous flying robots.

    Science.gov (United States)

    Virágh, Csaba; Vásárhelyi, Gábor; Tarcai, Norbert; Szörényi, Tamás; Somorjai, Gergő; Nepusz, Tamás; Vicsek, Tamás

    2014-06-01

    Animal swarms displaying a variety of typical flocking patterns would not exist without the underlying safe, optimal and stable dynamics of the individuals. The emergence of these universal patterns can be efficiently reconstructed with agent-based models. If we want to reproduce these patterns with artificial systems, such as autonomous aerial robots, agent-based models can also be used in their control algorithms. However, finding the proper algorithms and thus understanding the essential characteristics of the emergent collective behaviour requires thorough and realistic modeling of the robot and also the environment. In this paper, we first present an abstract mathematical model of an autonomous flying robot. The model takes into account several realistic features, such as time delay and locality of communication, inaccuracy of the on-board sensors and inertial effects. We present two decentralized control algorithms. One is based on a simple self-propelled flocking model of animal collective motion, the other is a collective target tracking algorithm. Both algorithms contain a viscous friction-like term, which aligns the velocities of neighbouring agents parallel to each other. We show that this term can be essential for reducing the inherent instabilities of such a noisy and delayed realistic system. We discuss simulation results on the stability of the control algorithms, and perform real experiments to show the applicability of the algorithms on a group of autonomous quadcopters. In our case, bio-inspiration works in two ways. On the one hand, the whole idea of trying to build and control a swarm of robots comes from the observation that birds tend to flock to optimize their behaviour as a group. On the other hand, by using a realistic simulation framework and studying the group behaviour of autonomous robots we can learn about the major factors influencing the flight of bird flocks.

  6. Friction and wear in sodium

    International Nuclear Information System (INIS)

    Hoffman, N.J.; Droher, J.J.

    1973-01-01

    In the design of a safe and reliable sodium-cooled reactor one of the more important problem areas is that of friction and wear of components immersed in liquid sodium or exposed to sodium vapor. Sodium coolant at elevated temperatures may severely affect most oxide-bearing surface layers which provide corrosion resistance and, to some extent, lubrication and surface hardness. Consequently, accelerated deterioration may be experienced on engaged-motion contact surfaces, which could result in unexpected reactor shutdown from component malfunction or failure due to galling and seizure. An overall view of the friction and wear phenomena encountered during oscillatory rubbing of surfaces in high-temperature, liquid-sodium environments is presented. Specific data generated at the Liquid Metal Engineering Center (LMEC) on this subject is also presented. (U.S.)

  7. Internal friction in irradiated textolite

    International Nuclear Information System (INIS)

    Zajkin, Yu.A.; Kozhamkulov, B.A.; Koztaeva, U.P.

    1996-01-01

    Structural relaxation in irradiated textolite of ST and ST-EhTF trade marks presenting pressed material got by method of impregnation of fibreglass by phenole and epoxytriphenole binders relatively. Measuring of temperature dependences of internal friction (TDIF) is carried out in torsional pendulum at oscillation frequency 0.6-1.0 Hz before and after irradiation by stopped gamma-quanta with energy 3 MeV on electron accelerator EhLU-4. α and β peaks, related with segments motion in base and side chains of macromolecular have being observed on TDIF of all textolite. Growth of peaks height after irradiation evident about increase of segments mobility in base chain and about de-freezing of segments in side chains and it could be considered as qualitative measure of radiation destruction rate. Comparison of temperature dependences of internal friction indicates on higher radiation stability of textolite of ST-EhTF trade mark

  8. [Robotics in pediatric surgery].

    Science.gov (United States)

    Camps, J I

    2011-10-01

    Despite the extensive use of robotics in the adult population, the use of robotics in pediatrics has not been well accepted. There is still a lack of awareness from pediatric surgeons on how to use the robotic equipment, its advantages and indications. Benefit is still controversial. Dexterity and better visualization of the surgical field are one of the strong values. Conversely, cost and a lack of small instruments prevent the use of robotics in the smaller patients. The aim of this manuscript is to present the controversies about the use of robotics in pediatric surgery.

  9. Low cost submarine robot

    Directory of Open Access Journals (Sweden)

    Ponlachart Chotikarn

    2010-10-01

    Full Text Available A submarine robot is a semi-autonomous submarine robot used mainly for marine environmental research. We aim todevelop a low cost, semi-autonomous submarine robot which is able to travel underwater. The robot’s structure was designedand patented using a novel idea of the diving system employing a volume adjustment mechanism to vary the robot’s density.A light weight, flexibility and small structure provided by PVC can be used to construct the torpedo-liked shape robot.Hydraulic seal and O-ring rubbers are used to prevent water leaking. This robot is controlled by a wired communicationsystem.

  10. Advances in robot kinematics

    CERN Document Server

    Khatib, Oussama

    2014-01-01

    The topics addressed in this book cover the whole range of kinematic analysis, synthesis and design and consider robotic systems possessing serial, parallel and cable driven mechanisms. The robotic systems range from being less than fully mobile to kinematically redundant to overconstrained.  The fifty-six contributions report the latest results in robot kinematics with emphasis on emerging areas such as design and control of humanoids or humanoid subsystems. The book is of interest to researchers wanting to bring their knowledge up to date regarding modern topics in one of the basic disciplines in robotics, which relates to the essential property of robots, the motion of mechanisms.

  11. Roll paper pilot. [mathematical model for predicting pilot rating of aircraft in roll task

    Science.gov (United States)

    Naylor, F. R.; Dillow, J. D.; Hannen, R. A.

    1973-01-01

    A mathematical model for predicting the pilot rating of an aircraft in a roll task is described. The model includes: (1) the lateral-directional aircraft equations of motion; (2) a stochastic gust model; (3) a pilot model with two free parameters; and (4) a pilot rating expression that is a function of rms roll angle and the pilot lead time constant. The pilot gain and lead time constant are selected to minimize the pilot rating expression. The pilot parameters are then adjusted to provide a 20% stability margin and the adjusted pilot parameters are used to compute a roll paper pilot rating of the aircraft/gust configuration. The roll paper pilot rating was computed for 25 aircraft/gust configurations. A range of actual ratings from 2 to 9 were encountered and the roll paper pilot ratings agree quite well with the actual ratings. In addition there is good correlation between predicted and measured rms roll angle.

  12. Plasmonic color metasurfaces fabricated by a high speed roll-to-roll method

    DEFF Research Database (Denmark)

    Murthy, Swathi; Pranov, Henrik; Feidenhans'l, Nikolaj Agentoft

    2017-01-01

    Lab-scale plasmonic color printing using nano-structured and subsequently metallized surfaces have been demonstrated to provide vivid colors. However, upscaling these structures for large area manufacturing is extremely challenging due to the requirement of nanometer precision of metal thickness....... In this study, we have investigated a plasmonic color meta-surface design that can be easily upscaled. We have demonstrated the feasibility of fabrication of these plasmonic color surfaces by a high-speed roll-to-roll method, comprising roll-to-roll extrusion coating at 10 m min-1 creating a polymer foil having...... 100 nm deep pits of varying sub-wavelength diameter and pitch length. Subsequently this polymer foil was metallized and coated also by high-speed roll-to-roll methods. The perceived colors have high tolerance towards the thickness of the metal layer, when this thickness exceeds the depths of the pits...

  13. Internal friction in uranium dioxide

    International Nuclear Information System (INIS)

    Paulin Filho, Pedro Iris

    1979-01-01

    The uranium dioxide inelastic properties were studied measuring internal friction at low frequencies (of the order of 1 Hz). The work was developed in the 160 to 400 deg C temperature range. The effect of stoichiometry variation was studied oxidizing the sample with consequent change of the defect structure originally present in the non-stoichiometric uranium dioxide. The presence of a wide and irregular peak due to oxidation was observed at low temperatures. Activation energy calculations indicated the occurrence of various relaxation processes and assuming the existence of a peak between - 80 and - 70 deg C , the absolute value obtained for the activation energy (0,54 eV) is consistent with the observed values determined at medium and high frequencies for the stress induced reorientation of defects. The microstructure effect on the inelastic properties was studied for stoichiometric uranium dioxide, by varying grain size and porosity. These parameters have influence on the high temperature measurements of internal friction. The internal friction variation for temperatures higher than 340 deg C is thought to be due to grain boundary relaxation phenomena. (author)

  14. Friction of elastomer-on-glass system and direct observation of its frictional interface

    International Nuclear Information System (INIS)

    Okamoto, Yoshihiro; Nishio, Kazuyuki; Sugiura, Jun-ichi; Hirano, Motohisa; Nitta, Takahiro

    2007-01-01

    We performed a study on the static friction of PDMS elastomers with well-defined surface topography sliding over glass. An experimental setup for simultaneous measurements of friction force and direct observations of frictional interface has been developed. The static friction force was nearly proportional to normal load. The static friction force was independent of stick time. The simultaneous measurements revealed that the static friction force was proportional to the total area of contact. The coefficient was nearly independent of the surface topography of PDMS elastomers

  15. Robots and lattice automata

    CERN Document Server

    Adamatzky, Andrew

    2015-01-01

    The book gives a comprehensive overview of the state-of-the-art research and engineering in theory and application of Lattice Automata in design and control of autonomous Robots. Automata and robots share the same notional meaning. Automata (originated from the latinization of the Greek word “αυτόματον”) as self-operating autonomous machines invented from ancient years can be easily considered the first steps of robotic-like efforts. Automata are mathematical models of Robots and also they are integral parts of robotic control systems. A Lattice Automaton is a regular array or a collective of finite state machines, or automata. The Automata update their states by the same rules depending on states of their immediate neighbours. In the context of this book, Lattice Automata are used in developing modular reconfigurable robotic systems, path planning and map exploration for robots, as robot controllers, synchronisation of robot collectives, robot vision, parallel robotic actuators. All chapters are...

  16. An optimal pole-matching observer design for estimating tyre-road friction force

    Science.gov (United States)

    Faraji, Mohammad; Johari Majd, Vahid; Saghafi, Behrooz; Sojoodi, Mahdi

    2010-10-01

    In this paper, considering the dynamical model of tyre-road contacts, we design a nonlinear observer for the on-line estimation of tyre-road friction force using the average lumped LuGre model without any simplification. The design is the extension of a previously offered observer to allow a muchmore realistic estimation by considering the effect of the rolling resistance and a term related to the relative velocity in the observer. Our aim is not to introduce a new friction model, but to present a more accurate nonlinear observer for the assumed model. We derive linear matrix equality conditions to obtain an observer gain with minimum pole mismatch for the desired observer error dynamic system. We prove the convergence of the observer for the non-simplified model. Finally, we compare the performance of the proposed observer with that of the previously mentioned nonlinear observer, which shows significant improvement in the accuracy of estimation.

  17. Friction torque of wind-turbine pitch bearings – comparison of experimental results with available models

    Directory of Open Access Journals (Sweden)

    M. Stammler

    2018-03-01

    Full Text Available Pitch bearings of wind turbines are large, grease-lubricated rolling bearings that connect the rotor blades with the rotor hub. They are used to turn the rotor blades to control the power output and/or structural loads of the turbine. Common actuators turning the blades are hydraulic cylinders or electrical motor–gearbox combinations. In order to design pitch actuator systems that are able to turn the blades reliably without imposing an excessive power demand, it is necessary to predict the friction torque of pitch bearings for different operating conditions. In this paper, the results of torque measurements under load are presented and compared to results obtained using different calculation models. The results of this comparison indicate the various sources of friction that should be taken into account for a reliable calculation model.

  18. Marine Robot Autonomy

    CERN Document Server

    2013-01-01

    Autonomy for Marine Robots provides a timely and insightful overview of intelligent autonomy in marine robots. A brief history of this emerging field is provided, along with a discussion of the challenges unique to the underwater environment and their impact on the level of intelligent autonomy required.  Topics covered at length examine advanced frameworks, path-planning, fault tolerance, machine learning, and cooperation as relevant to marine robots that need intelligent autonomy.  This book also: Discusses and offers solutions for the unique challenges presented by more complex missions and the dynamic underwater environment when operating autonomous marine robots Includes case studies that demonstrate intelligent autonomy in marine robots to perform underwater simultaneous localization and mapping  Autonomy for Marine Robots is an ideal book for researchers and engineers interested in the field of marine robots.      

  19. Frictional Compliant Haptic Contact and Deformation of Soft Objects

    Directory of Open Access Journals (Sweden)

    Naci Zafer

    2016-05-01

    Full Text Available This paper is concerned with compliant haptic contact and deformation of soft objects. A human soft fingertip model is considered to act as the haptic interface and is brought into contact with and deforms a discrete surface. A nonlinear constitutive law is developed in predicting normal forces and, for the haptic display of surface texture, motions along the surface are also resisted at various rates by accounting for dynamic Lund-Grenoble (LuGre frictional forces. For the soft fingertip to apply forces over an area larger than a point, normal and frictional forces are distributed around the soft fingertip contact location on the deforming surface. The distribution is realized based on a kernel smoothing function and by a nonlinear spring-damper net around the contact point. Experiments conducted demonstrate the accuracy and effectiveness of our approach in real-time haptic rendering of a kidney surface. The resistive (interaction forces are applied at the user fingertip bone edge. A 3-DoF parallel robotic manipulator equipped with a constraint based controller is used for the implementation. By rendering forces both in lateral and normal directions, the designed haptic interface system allows the user to realistically feel both the geometrical and mechanical (nonlinear properties of the deforming kidney.

  20. The effect of friction in coulombian damper

    Science.gov (United States)

    Wahad, H. S.; Tudor, A.; Vlase, M.; Cerbu, N.; Subhi, K. A.

    2017-02-01

    The study aimed to analyze the damping phenomenon in a system with variable friction, Stribeck type. Shock absorbers with limit and dry friction, is called coulombian shock-absorbers. The physical damping vibration phenomenon, in equipment, is based on friction between the cushioning gasket and the output regulator of the shock-absorber. Friction between them can be dry, limit, mixture or fluid. The friction is depending on the contact pressure and lubricant presence. It is defined dimensionless form for the Striebeck curve (µ friction coefficient - sliding speed v). The friction may damp a vibratory movement or can maintain it (self-vibration), depending on the µ with v (it can increase / decrease or it can be relative constant). The solutions of differential equation of movement are obtained for some work condition of one damper for automatic washing machine. The friction force can transfer partial or total energy or generates excitation energy in damper. The damping efficiency is defined and is determined analytical for the constant friction coefficient and for the parabolic friction coefficient.

  1. Kinetic Friction of Sport Fabrics on Snow

    Directory of Open Access Journals (Sweden)

    Werner Nachbauer

    2016-03-01

    Full Text Available After falls, skiers or snowboarders often slide on the slope and may collide with obstacles. Thus, the skier’s friction on snow is an important factor to reduce incidence and severity of impact injuries. The purpose of this study was to measure snow friction of different fabrics of ski garments with respect to roughness, speed, and contact pressure. Three types of fabrics were investigated: a commercially available ski overall, a smooth downhill racing suit, and a dimpled downhill racing suit. Friction was measured for fabrics taped on a short ski using a linear tribometer. The fabrics’ roughness was determined by focus variation microscopy. Friction coefficients were between 0.19 and 0.48. Roughness, friction coefficient, and friction force were highest for the dimpled race suit. The friction force of the fabrics was higher for the higher contact pressure than for the lower one at all speeds. It was concluded that the main friction mechanism for the fabrics was dry friction. Only the fabric with the roughest surface showed friction coefficients, which were high enough to sufficiently decelerate a sliding skier on beginner and intermediate slopes.

  2. Nano-friction behavior of phosphorene.

    Science.gov (United States)

    Bai, Lichun; Liu, Bo; Srikanth, Narasimalu; Tian, Yu; Zhou, Kun

    2017-09-01

    Nano-friction of phosphorene plays a significant role in affecting the controllability and efficiency of applying strain engineering to tune its properties. So far, the friction behavior of phosphorene has not been studied. This work studies the friction of single-layer and bilayer phosphorene on an amorphous silicon substrate by sliding a rigid tip. For the single-layer phosphorene, it is found that its friction is highly anisotropic, i.e. the friction is larger along the armchair direction than that along the zigzag direction. Moreover, pre-strain of the phosphorene also exhibits anisotropic effects. The friction increases with the pre-strain along the zigzag direction, but decreases with that along the armchair direction. Furthermore, the strong adhesion between the phosphorene and its substrate increases the friction between the phosphorene and the tip. For bilayer phosphorene, its friction highly depends on its stacking mode, which determines the contact interface with a commensurate or incommensurate pattern. This friction behavior is quite unique and greatly differs from that of graphene and molybdenum disulfide. Detailed analysis reveals that this behavior results from the combination effect of the friction contact area, the potential-energy profile of phosphorene, and its unique elongation.

  3. Rolling of molybdenum and niobium tubes on cold-rolling mill with high stiff stand

    Energy Technology Data Exchange (ETDEWEB)

    Potapov, I N; Shejkh-Ali, A D; Filimonov, G V; Lunev, A G

    1984-03-01

    To develop the technique of tube production the process of rolling is studied and comparative evaluation of the structure formed is carried out. It is shown that billets of rods deformed by screw rolling have the improved plastic properties and are deformed on cold-rolling mill (CRM) with a high degree of reduction without defect formation. High stiff stand of the CRM permits to produce high-quality molybdenum tubes.

  4. Decision Support for the Rolling Stock Dispatcher

    DEFF Research Database (Denmark)

    Groth, Julie Jespersen

    Real-time recovery is receiving a fast growing interest in an increasingly competitive railway operation market. This thesis considers the area of rolling stock dispatching which is one of the typical real-time railway dispatching problems. All work of the thesis is based on the network...... and planning processes of the railway operator DSB S-tog a/s. In the thesis the problems existing in the railway planning process from the strategic to real-time level are briefly sketched. Network planning, line planning, timetabling, crew and rolling stock planning is outlined and relevant references...... are given. Specifically the thesis references the operation research studies based on the railway operation of DSB S-tog a/s. Subsequently the process of dispatching is outlined with a specific emphasis on rolling stock. The rolling stock recovery problem is the problem of assigning train units to train...

  5. Terras: NATO õppuste roll Euroopas kasvab

    Index Scriptorium Estoniae

    2013-01-01

    Kaitseväe juhataja kindralmajor Riho Terrase sõnul suureneb lähiaastatel NATO õppuste roll Euroopas, sest Afganistanis sõdides saadud kogemust on vaja säilitada ning kasutada seda kollektiivkaitse tugevdamiseks

  6. Texture analysis of a friction stir processed 6061-T6 aluminum alloy using neutron diffraction

    International Nuclear Information System (INIS)

    Woo, W.; Choo, H.; Brown, D.W.; Vogel, S.C.; Liaw, P.K.; Feng, Z.

    2006-01-01

    Time-of-flight neutron diffraction was used to investigate the texture changes in friction stir-processed (FSP) 6061-T6 aluminum alloy plates. Two different specimens were prepared with the purpose of separating the effects of frictional heating and severe plastic deformation on the changes of the preferred orientation in the as-received rolled plates: a plate processed with both stirring pin and tool shoulder, i.e., a regular FSP plate subjected to both severe plastic deformation and frictional heating (Case 1); and a plate processed only with the tool shoulder, i.e., subjected mainly to frictional heating (Case 2). The diffraction peak intensities provide insights into the texture variations at various locations across the centerline and through the thickness of the FSP plates. Comparison of the texture variations between Cases 1 and 2 clearly shows that the severe plastic deformation from the stirring pin affects the preferred orientation during the FSP, while heating alone from the tool shoulder has little effect

  7. Disk partition function and oscillatory rolling tachyons

    International Nuclear Information System (INIS)

    Jokela, Niko; Jaervinen, Matti; Keski-Vakkuri, Esko; Majumder, Jaydeep

    2008-01-01

    An exact cubic open string field theory rolling tachyon solution was recently found by Kiermaier et al and Schnabl. This oscillatory solution has been argued to be related by a field redefinition to the simple exponential rolling tachyon deformation of boundary conformal theory. In the latter approach, the disk partition function takes a simple form. Out of curiosity, we compute the disk partition function for an oscillatory tachyon profile, and find that the result is nevertheless almost the same

  8. Maintenance in Railway Rolling Stock Rescheduling for Passenger Railways

    NARCIS (Netherlands)

    J.C. Wagenaar (Joris); L.G. Kroon (Leo)

    2015-01-01

    textabstractThis paper addresses the Rolling Stock Rescheduling Problem (RSRP), while taking maintenance appointments into account. After a disruption, the rolling stock of passenger trains has to be rescheduled in order to maintain a feasible rolling stock circulation. A limited number of rolling

  9. Robotic Tactile Sensing Technologies and System

    CERN Document Server

    Dahiya, Ravinder S

    2013-01-01

    Future robots are expected to work closely and interact safely with real-world objects and humans alike. Sense of touch is important in this context, as it helps estimate properties such as shape, texture, hardness, material type and many more; provides action related information, such as slip detection; and helps carrying out actions such as rolling an object between fingers without dropping it. This book presents an in-depth description of the solutions available for gathering tactile data, obtaining aforementioned tactile information from the data and effectively using the same in various robotic tasks. Better integration of tactile sensors on a robot’s body is prerequisite for the effective utilization of tactile data. For this reason, the hardware, software and application related issues (and resulting trade-offs) that must be considered to make tactile sensing an effective component of robotic platforms are discussed in-depth.To this end, human touch sensing has also been explored. The design hints co...

  10. Friction Anisotropy with Respect to Topographic Orientation

    Science.gov (United States)

    Yu, Chengjiao; Wang, Q. Jane

    2012-01-01

    Friction characteristics with respect to surface topographic orientation were investigated using surfaces of different materials and fabricated with grooves of different scales. Scratching friction tests were conducted using a nano-indentation-scratching system with the tip motion parallel or perpendicular to the groove orientation. Similar friction anisotropy trends were observed for all the surfaces studied, which are (1) under a light load and for surfaces with narrow grooves, the tip motion parallel to the grooves offers higher friction coefficients than does that perpendicular to them, (2) otherwise, equal or lower friction coefficients are found under this motion. The influences of groove size relative to the diameter of the mating tip (as a representative asperity), surface contact stiffness, contact area, and the characteristic stiction length are discussed. The appearance of this friction anisotropy is independent of material; however, the boundary and the point of trend transition depend on material properties. PMID:23248751

  11. High temperature internal friction in pure aluminium

    International Nuclear Information System (INIS)

    Aboagye, J.K.; Payida, D.S.

    1982-05-01

    The temperature dependence of internal friction of nearly pure aluminium (99.99% aluminium) has been carefully measured as a function of annealing temperature and hence grain size. The results indicate that, provided the frequency and annealing temperature are held constant, the internal friction increases with temperature until some maximum value is attained and then begins to go down as the temperature is further increased. It is also noted that the internal friction decreases with annealing temperature and that annealing time has the same effect as annealing temperature. It is also noted that the internal friction peak is shifted towards higher temperatures as annealing temperature is increased. It is surmised that the grain size or the total grain boundary volume determines the height of the internal friction curve and that the order-disorder transitions at the grain boundaries induced by both entropy and energy gradients give rise to internal friction peaks in polycrystals. (author)

  12. Static friction between rigid fractal surfaces.

    Science.gov (United States)

    Alonso-Marroquin, Fernando; Huang, Pengyu; Hanaor, Dorian A H; Flores-Johnson, E A; Proust, Gwénaëlle; Gan, Yixiang; Shen, Luming

    2015-09-01

    Using spheropolygon-based simulations and contact slope analysis, we investigate the effects of surface topography and atomic scale friction on the macroscopically observed friction between rigid blocks with fractal surface structures. From our mathematical derivation, the angle of macroscopic friction is the result of the sum of the angle of atomic friction and the slope angle between the contact surfaces. The latter is obtained from the determination of all possible contact slopes between the two surface profiles through an alternative signature function. Our theory is validated through numerical simulations of spheropolygons with fractal Koch surfaces and is applied to the description of frictional properties of Weierstrass-Mandelbrot surfaces. The agreement between simulations and theory suggests that for interpreting macroscopic frictional behavior, the descriptors of surface morphology should be defined from the signature function rather than from the slopes of the contacting surfaces.

  13. Roll-to-roll printed silver nanowires for increased stability of flexible ITO-free organic solar cell modules

    DEFF Research Database (Denmark)

    Benatto, Gisele Alves dos Reis; Roth, Bérenger; Corazza, Michael

    2016-01-01

    We report the use of roll-to-roll printed silver nanowire networks as front electrodes for fully roll-to-roll processed flexible indium-tin-oxide (ITO) free OPV modules. We prepared devices with two types of back electrodes, a simple PEDOT:PSS back electrode and a PEDOT:PSS back electrode...

  14. 75 FR 42782 - Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil, Japan, and Russia

    Science.gov (United States)

    2010-07-22

    ...)] Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil, Japan, and Russia AGENCY: United... Brazil and Japan, and the suspended investigation on hot-rolled steel from Russia. SUMMARY: The... Japan, and the suspended investigation on hot-rolled steel from Russia would be likely to lead to...

  15. 75 FR 62566 - Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil, Japan, and Russia

    Science.gov (United States)

    2010-10-12

    ...)] Hot-Rolled Flat-Rolled Carbon-Quality Steel Products From Brazil, Japan, and Russia AGENCY: United... antidumping duty investigation on hot-rolled steel from Russia. SUMMARY: The Commission hereby gives notice of... suspended investigation on hot-rolled steel from Russia would be likely to lead to continuation or...

  16. Non-manufacturing applications of robotics

    International Nuclear Information System (INIS)

    Dauchez, P.

    2000-12-01

    This book presents the different non-manufacturing sectors of activity where robotics can have useful or necessary applications: underwater robotics, agriculture robotics, road work robotics, nuclear robotics, medical-surgery robotics, aids to disabled people, entertainment robotics. Service robotics has been voluntarily excluded because this developing sector is not mature yet. (J.S.)

  17. Evolution of robotic arms.

    Science.gov (United States)

    Moran, Michael E

    2007-01-01

    The foundation of surgical robotics is in the development of the robotic arm. This is a thorough review of the literature on the nature and development of this device with emphasis on surgical applications. We have reviewed the published literature and classified robotic arms by their application: show, industrial application, medical application, etc. There is a definite trend in the manufacture of robotic arms toward more dextrous devices, more degrees-of-freedom, and capabilities beyond the human arm. da Vinci designed the first sophisticated robotic arm in 1495 with four degrees-of-freedom and an analog on-board controller supplying power and programmability. von Kemplen's chess-playing automaton left arm was quite sophisticated. Unimate introduced the first industrial robotic arm in 1961, it has subsequently evolved into the PUMA arm. In 1963 the Rancho arm was designed; Minsky's Tentacle arm appeared in 1968, Scheinman's Stanford arm in 1969, and MIT's Silver arm in 1974. Aird became the first cyborg human with a robotic arm in 1993. In 2000 Miguel Nicolalis redefined possible man-machine capacity in his work on cerebral implantation in owl-monkeys directly interfacing with robotic arms both locally and at a distance. The robotic arm is the end-effector of robotic systems and currently is the hallmark feature of the da Vinci Surgical System making its entrance into surgical application. But, despite the potential advantages of this computer-controlled master-slave system, robotic arms have definite limitations. Ongoing work in robotics has many potential solutions to the drawbacks of current robotic surgical systems.

  18. Is Ethics of Robotics about Robots? Philosophy of Robotics Beyond Realism and Individualilsm.

    NARCIS (Netherlands)

    Coeckelbergh, Mark

    2011-01-01

    If we are doing ethics of robotics, what exactly is the object of our inquiry? This paper challenges 'individualist' robot ontology and 'individualist' social philosophy of robots. It is argued that ethics of robotics should not study and evaluate robotics exclusively in terms of individual

  19. Investigation of the Microstructure Evolution and Deformation Mechanisms of a Mg-Zn-Zr-RE Twin-Roll-Cast Magnesium Sheet by In-Situ Experimental Techniques

    Czech Academy of Sciences Publication Activity Database

    Máthis, K.; Horváth, Klaudia; Farkas, Gergely; Choe, H.; Shin, K. S.; Vinogradov, A.

    2018-01-01

    Roč. 11, č. 2 (2018), č. článku 200. ISSN 1996-1944 R&D Projects: GA ČR GB14-36566G; GA MŠk EF16_013/0001794 Institutional support: RVO:61389005 Keywords : magnesium * twin roll casting * neutron diffraction * acoustic emission * twinning * yield strength Subject RIV: JL - Materials Fatigue, Friction Mechanics OBOR OECD: Audio engineering, reliability analysis Impact factor: 2.654, year: 2016

  20. Friction measurement in a hip wear simulator.

    Science.gov (United States)

    Saikko, Vesa

    2016-05-01

    A torque measurement system was added to a widely used hip wear simulator, the biaxial rocking motion device. With the rotary transducer, the frictional torque about the drive axis of the biaxial rocking motion mechanism was measured. The principle of measuring the torque about the vertical axis above the prosthetic joint, used earlier in commercial biaxial rocking motion simulators, was shown to sense only a minor part of the total frictional torque. With the present method, the total frictional torque of the prosthetic hip was measured. This was shown to consist of the torques about the vertical axis above the joint and about the leaning axis. Femoral heads made from different materials were run against conventional and crosslinked polyethylene acetabular cups in serum lubrication. Regarding the femoral head material and the type of polyethylene, there were no categorical differences in frictional torque with the exception of zirconia heads, with which the lowest values were obtained. Diamond-like carbon coating of the CoCr femoral head did not reduce friction. The friction factor was found to always decrease with increasing load. High wear could increase the frictional torque by 75%. With the present system, friction can be continuously recorded during long wear tests, so the effect of wear on friction with different prosthetic hips can be evaluated. © IMechE 2016.