Characterization of piezoelectric macrofiber composite actuated winglets

International Nuclear Information System (INIS)

Guha, T K; Oates, W S; Kumar, R

2015-01-01

The present study primarily focuses on the design, development, and structural characterization of an oscillating winglet actuated using a piezoelectric macrofiber composite (MFC). The primary objective is to study the effect of controlled wingtip oscillations on the evolution of wingtip vortices, with a goal of weakening these potentially harmful tip vortices by introducing controlled instabilities through both spatial and temporal perturbations producible through winglet oscillations. MFC-actuated winglets have been characterized under different input excitation and pressure-loading conditions. The winglet oscillations show bimodal behavior for both structural and actuation modes of resonance. The oscillatory amplitude at these actuation modes increases linearly with the magnitude of excitation. During wind-tunnel tests, fluid-structure interactions led to structural vibrations of the wing. The effect of these vibrations on the overall winglet oscillations decreased when the strength of actuation increased. At high input excitation, the actuated winglet was capable of generating controlled oscillations. As a proof of concept, the current study has demonstrated that microfiber composite-actuated winglets produce sufficient displacements to alter the development of the wingtip vortex. (paper)

High-authority smart material integrated electric actuator

Science.gov (United States)

Weisensel, G. N.; Pierce, Thomas D.; Zunkel, Gary

1997-05-01

For many current applications, hydraulic power is still the preferred method of gaining mechanical advantage. However, in many of these applications, this power comes with the penalties of high weight, size, cost, and maintenance due to the system's distributed nature and redundancy requirements. A high authority smart material Integrated Electric Actuator (IEA) is a modular, self-contained linear motion device that is capable of producing dynamic output strokes similar to those of hydraulic actuators yet at significantly reduced weight and volume. It provides system simplification and miniaturization. This actuator concept has many innovative features, including a TERFENOL-D-based pump, TERFENOL-D- based active valves, control algorithms, a displacement amplification unit and integrated, unitized packaging. The IEA needs only electrical power and a control command signal as inputs to provide high authority, high response rate actuation. This approach is directly compatible with distributed control strategies. Aircraft control, automotive brakes and fuel injection, and fluid power delivery are just some examples of the IEA's pervasive applications in aerospace, defense and commercial systems.

Adaptive Fault-Tolerant Synchronization Control of a Class of Complex Dynamical Networks With General Input Distribution Matrices and Actuator Faults.

Science.gov (United States)

Li, Xiao-Jian; Yang, Guang-Hong

2017-03-01

This paper is concerned with the problem of adaptive fault-tolerant synchronization control of a class of complex dynamical networks (CDNs) with actuator faults and unknown coupling weights. The considered input distribution matrix is assumed to be an arbitrary matrix, instead of a unit one. Within this framework, an adaptive fault-tolerant controller is designed to achieve synchronization for the CDN. Moreover, a convex combination technique and an important graph theory result are developed, such that the rigorous convergence analysis of synchronization errors can be conducted. In particular, it is shown that the proposed fault-tolerant synchronization control approach is valid for the CDN with both time-invariant and time-varying coupling weights. Finally, two simulation examples are provided to validate the effectiveness of the theoretical results.

Self-organizing sensing and actuation for automatic control

Science.gov (United States)

Cheng, George Shu-Xing

2017-07-04

A Self-Organizing Process Control Architecture is introduced with a Sensing Layer, Control Layer, Actuation Layer, Process Layer, as well as Self-Organizing Sensors (SOS) and Self-Organizing Actuators (SOA). A Self-Organizing Sensor for a process variable with one or multiple input variables is disclosed. An artificial neural network (ANN) based dynamic modeling mechanism as part of the Self-Organizing Sensor is described. As a case example, a Self-Organizing Soft-Sensor for CFB Boiler Bed Height is presented. Also provided is a method to develop a Self-Organizing Sensor.

Rise time reduction of thermal actuators operated in air and water through optimized pre-shaped open-loop driving

International Nuclear Information System (INIS)

Larsen, T; Doll, J C; Loizeau, F; Pruitt, B L; Hosseini, N; Fantner, G E; Peng, A W; Ricci, A J

2017-01-01

Electrothermal actuators have many advantages compared to other actuators used in micro-electro-mechanical systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10–90% rise time of 85 μ s in air and 234 μ s in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10–90% rise time from 85 μ s to 3 μ s in air and from 234 μ s to 5 μ s in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate. (paper)

Rise Time Reduction of Thermal Actuators Operated in Air and Water through Optimized Pre-Shaped Open-Loop Driving.

Science.gov (United States)

Larsen, T; Doll, J C; Loizeau, F; Hosseini, N; Peng, A W; Fantner, G; Ricci, A J; Pruitt, B L

2017-01-01

Electrothermal actuators have many advantages compared to other actuators used in Micro-Electro-Mechanical Systems (MEMS). They are simple to design, easy to fabricate and provide large displacements at low voltages. Low voltages enable less stringent passivation requirements for operation in liquid. Despite these advantages, thermal actuation is typically limited to a few kHz bandwidth when using step inputs due to its intrinsic thermal time constant. However, the use of pre-shaped input signals offers a route for reducing the rise time of these actuators by orders of magnitude. We started with an electrothermally actuated cantilever having an initial 10-90% rise time of 85 μs in air and 234 μs in water for a standard open-loop step input. We experimentally characterized the linearity and frequency response of the cantilever when operated in air and water, allowing us to obtain transfer functions for the two cases. We used these transfer functions, along with functions describing desired reduced rise-time system responses, to numerically simulate the required input signals. Using these pre-shaped input signals, we improved the open-loop 10-90% rise time from 85 μs to 3 μs in air and from 234 μs to 5 μs in water, an improvement by a factor of 28 and 47, respectively. Using this simple control strategy for MEMS electrothermal actuators makes them an attractive alternative to other high speed micromechanical actuators such as piezoelectric stacks or electrostatic comb structures which are more complex to design, fabricate, or operate.

MOSFET Switching Circuit Protects Shape Memory Alloy Actuators

Science.gov (United States)

Gummin, Mark A.

2011-01-01

A small-footprint, full surface-mount-component printed circuit board employs MOSFET (metal-oxide-semiconductor field-effect transistor) power switches to switch high currents from any input power supply from 3 to 30 V. High-force shape memory alloy (SMA) actuators generally require high current (up to 9 A at 28 V) to actuate. SMA wires (the driving element of the actuators) can be quickly overheated if power is not removed at the end of stroke, which can damage the wires. The new analog driver prevents overheating of the SMA wires in an actuator by momentarily removing power when the end limit switch is closed, thereby allowing complex control schemes to be adopted without concern for overheating. Either an integral pushbutton or microprocessor-controlled gate or control line inputs switch current to the actuator until the end switch line goes from logic high to logic low state. Power is then momentarily removed (switched off by the MOSFET). The analog driver is suited to use with nearly any SMA actuator.

Directly Printable Flexible Strain Sensors for Bending and Contact Feedback of Soft Actuators

Directory of Open Access Journals (Sweden)

Khaled Elgeneidy

2018-02-01

Full Text Available This paper presents a fully printable sensorized bending actuator that can be calibrated to provide reliable bending feedback and simple contact detection. A soft bending actuator following a pleated morphology, as well as a flexible resistive strain sensor, were directly 3D printed using easily accessible FDM printer hardware with a dual-extrusion tool head. The flexible sensor was directly welded to the bending actuator’s body and systematically tested to characterize and evaluate its response under variable input pressure. A signal conditioning circuit was developed to enhance the quality of the sensory feedback, and flexible conductive threads were used for wiring. The sensorized actuator’s response was then calibrated using a vision system to convert the sensory readings to real bending angle values. The empirical relationship was derived using linear regression and validated at untrained input conditions to evaluate its accuracy. Furthermore, the sensorized actuator was tested in a constrained setup that prevents bending, to evaluate the potential of using the same sensor for simple contact detection by comparing the constrained and free-bending responses at the same input pressures. The results of this work demonstrated how a dual-extrusion FDM printing process can be tuned to directly print highly customizable flexible strain sensors that were able to provide reliable bending feedback and basic contact detection. The addition of such sensing capability to bending actuators enhances their functionality and reliability for applications such as controlled soft grasping, flexible wearables, and haptic devices.

Active joint mechanism driven by multiple actuators made of flexible bags: a proposal of dual structural actuator.

Science.gov (United States)

Kimura, Hitoshi; Matsuzaki, Takuya; Kataoka, Mokutaro; Inou, Norio

2013-01-01

An actuator is required to change its speed and force depending on the situation. Using multiple actuators for one driving axis is one of the possible solutions; however, there is an associated problem of output power matching. This study proposes a new active joint mechanism using multiple actuators. Because the actuator is made of a flexible bag, it does not interfere with other actuators when it is depressurized. The proposed joint achieved coordinated motion of multiple actuators. This report also discusses a new actuator which has dual cylindrical structure. The cylinders are composed of flexible bags with different diameters. The joint torque is estimated based on the following factors: empirical formula for the flexible actuator torque, geometric relationship between the joint and the actuator, and the principle of virtual work. The prototype joint mechanism achieves coordinated motion of multiple actuators for one axis. With this motion, small inner actuator contributes high speed motion, whereas large outer actuator generates high torque. The performance of the prototype joint is examined by speed and torque measurements. The joint showed about 30% efficiency at 2.0 Nm load torque under 0.15 MPa air input.

An earthworm-like actuator using segmented solenoids

International Nuclear Information System (INIS)

Shin, Bu Hyun; Choi, Seung-Wook; Lee, Seung-Yop; Bang, Young-Bong

2011-01-01

A biomimetic actuator is developed using four segmented solenoids mimicking earthworm locomotion. The proposed actuator not only has a simple structure composed of cores and coils, but also enables bi-directional actuation and high speed locomotion regardless of friction conditions. We have implemented theoretical analysis to design the optimal profiles of input current signal for maximum speed and predict the output force and stroke. Experiments using a prototype show that the earthworm-like actuator travels with a speed above 60 mm s −1 regardless of friction conditions

Dynamic Characteristics of a Hydraulic Amplification Mechanism for Large Displacement Actuators Systems

Directory of Open Access Journals (Sweden)

Xavier Arouette

2010-03-01

Full Text Available We have developed a hydraulic displacement amplification mechanism (HDAM and studied its dynamic response when combined with a piezoelectric actuator. The HDAM consists of an incompressible fluid sealed in a microcavity by two largely deformable polydimethylsiloxane (PDMS membranes. The geometry with input and output surfaces having different cross-sectional areas creates amplification. By combining the HDAM with micro-actuators, we can amplify the input displacement generated by the actuators, which is useful for applications requiring large deformation, such as tactile displays. We achieved a mechanism offering up to 18-fold displacement amplification for static actuation and 12-fold for 55 Hz dynamic actuation.

Method for driving an actuator, actuator drive, and apparatus comprising an actuator

OpenAIRE

2010-01-01

An actuator driver circuit includes a drive signal source and an electrical damping element having a negative resistance connected in series with the drive signal source. A controllable switch is provided for selectively switching the electrical damping element into or put of a signal path from a drive signal source output to a driver circuit output, in order to selectively change the electrical damping of an actuator. For example, the electrical damping of a radial actuator or a focus actuat...

Fiber-Reinforced Origamic Robotic Actuator.

Science.gov (United States)

Yi, Juan; Chen, Xiaojiao; Song, Chaoyang; Wang, Zheng

2018-02-01

A novel pneumatic soft linear actuator Fiber-reinforced Origamic Robotic Actuator (FORA) is proposed with significant improvements on the popular McKibben-type actuators, offering nearly doubled motion range, substantially improved force profile, and significantly lower actuation pressure. The desirable feature set is made possible by a novel soft origamic chamber that expands radially while contracts axially when pressurized. Combining this new origamic chamber with a reinforcing fiber mesh, FORA generates very high traction force (over 150N) and very large contractile motion (over 50%) at very low input pressure (100 kPa). We developed quasi-static analytical models both to characterize the motion and forces and as guidelines for actuator design. Fabrication of FORA mostly involves consumer-grade three-dimensional (3D) printing. We provide a detailed list of materials and dimensions. Fabricated FORAs were tested on a dedicated platform against commercially available pneumatic artificial muscles from Shadow and Festo to showcase its superior performances and validate the analytical models with very good agreements. Finally, a robotic joint was developed driven by two antagonistic FORAs, to showcase the benefits of the performance improvements. With its simple structure, fully characterized mechanism, easy fabrication procedure, and highly desirable performance, FORA could be easily customized to application requirements and fabricated by anyone with access to a 3D printer. This will pave the way to the wider adaptation and application of soft robotic systems.

Optimization of actuator arrays for aircraft interior noise control

Science.gov (United States)

Cabell, R. H.; Lester, H. C.; Mathur, G. P.; Tran, B. N.

1993-01-01

A numerical procedure for grouping actuators in order to reduce the number of degrees of freedom in an active noise control system is evaluated using experimental data. Piezoceramic actuators for reducing aircraft interior noise are arranged into groups using a nonlinear optimization routine and clustering algorithm. An actuator group is created when two or more actuators are driven with the same control input. This procedure is suitable for active control applications where actuators are already mounted on a structure. The feasibility of this technique is demonstrated using measured data from the aft cabin of a Douglas DC-9 fuselage. The measured data include transfer functions between 34 piezoceramic actuators and 29 interior microphones and microphone responses due to the primary noise produced by external speakers. Control inputs for the grouped actuators were calculated so that a cost function, defined as a quadratic pressure term and a penalty term, was a minimum. The measured transfer functions and microphone responses are checked by comparing calculated noise reductions with measured noise reductions for four frequencies. The grouping procedure is then used to determine actuator groups that improve overall interior noise reductions by 5.3 to 15 dB, compared to the baseline experimental configuration.

Event-triggered decentralized adaptive fault-tolerant control of uncertain interconnected nonlinear systems with actuator failures.

Science.gov (United States)

Choi, Yun Ho; Yoo, Sung Jin

2018-06-01

This paper investigates the event-triggered decentralized adaptive tracking problem of a class of uncertain interconnected nonlinear systems with unexpected actuator failures. It is assumed that local control signals are transmitted to local actuators with time-varying faults whenever predefined conditions for triggering events are satisfied. Compared with the existing control-input-based event-triggering strategy for adaptive control of uncertain nonlinear systems, the aim of this paper is to propose a tracking-error-based event-triggering strategy in the decentralized adaptive fault-tolerant tracking framework. The proposed approach can relax drastic changes in control inputs caused by actuator faults in the existing triggering strategy. The stability of the proposed event-triggering control system is analyzed in the Lyapunov sense. Finally, simulation comparisons of the proposed and existing approaches are provided to show the effectiveness of the proposed theoretical result in the presence of actuator faults. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

A Cost-Effective 10-Bit D/A Converter for Digital-Input MOEMS Micromirror Actuation

Directory of Open Access Journals (Sweden)

Sergio Saponara

2010-01-01

Full Text Available The design of a 10-bit resistor-string digital-to-analog converter (DAC for MOEMS micromirror interfacing is addressed in this paper. The proposed DAC, realized in a 0.18-μm BCD technology, features a folded resistor-string stage with a switch matrix and address decoders plus an output voltage buffer stage. The proposed DAC and buffer circuitry are key elements of an innovative scanning micromirror actuator, characterized by direct digital input, full differential driving, and linear response. With respect to the the state-of-the-art resistor-string converters in similar technologies, the proposed DAC has comparable nonlinearity (INL, DNL performances while it has the advantage of a smaller area occupation, 0.17 mm2, including output buffer, and relatively low-power consumption, 200 μW at 500 kSPS and few μW in idle mode.

Fuzzy PID Feedback Control of Piezoelectric Actuator with Feedforward Compensation

Directory of Open Access Journals (Sweden)

Ziqiang Chi

2014-01-01

Full Text Available Piezoelectric actuator is widely used in the field of micro/nanopositioning. However, piezoelectric hysteresis introduces nonlinearity to the system, which is the major obstacle to achieve a precise positioning. In this paper, the Preisach model is employed to describe the hysteresis characteristic of piezoelectric actuator and an inverse Preisach model is developed to construct a feedforward controller. Considering that the analytical expression of inverse Preisach model is difficult to derive and not suitable for practical application, a digital inverse model is established based on the input and output data of a piezoelectric actuator. Moreover, to mitigate the compensation error of the feedforward control, a feedback control scheme is implemented using different types of control algorithms in terms of PID control, fuzzy control, and fuzzy PID control. Extensive simulation studies are carried out using the three kinds of control systems. Comparative investigation reveals that the fuzzy PID control system with feedforward compensation is capable of providing quicker response and better control accuracy than the other two ones. It provides a promising way of precision control for piezoelectric actuator.

Apparatus, system, and method for providing fabric-elastomer composites as pneumatic actuators

Science.gov (United States)

Martinez, Ramses V.; Whitesides, George M.

2017-10-25

Soft pneumatic actuators based on composites consisting of elastomers with embedded sheet or fiber structures (e.g., paper or fabric) that are flexible but not extensible are described. On pneumatic inflation, these actuators move anisotropically, based on the motions accessible by their composite structures. They are inexpensive, simple to fabricate, light in weight, and easy to actuate. This class of structure is versatile: the same principles of design lead to actuators that respond to pressurization with a wide range of motions (bending, extension, contraction, twisting, and others). Paper, when used to introduce anisotropy into elastomers, can be readily folded into three-dimensional structures following the principles of origami; these folded structures increase the stiffness and anisotropy of the elastomeric actuators, while keeping them light in weight.

Force-deflection behavior of piezoelectric actuators

Science.gov (United States)

Singh, Ashok K.; Nagpal, Pawan

2001-11-01

In the present endeavour, force - deflection behavior of various piezoelectric actuator configurations has been analyzed for performance comparison. The response of stack actuator has been simulated using MATLAB Simulink, in a stack actuator-pendulum configuration. During simulation, stack actuator has been used in charge control feedback mode, because of the advantage of low hysteresis, and high linearity. The model incorporates three compensation blocks, viz 1) a PID position controller, 2) a PI piezoelectric current controller, and 3) a dynamic force feedback. A typical stack actuator, having 130 layers, 1.20x10-4 m thickness, 3.46x10-5m2 cross sectional area, of PZT-5H type, has been utilized for simulation. The response of the system has been tested by applying a sinusoidal input of frequency 500 Hz, and waveform amplitude of 1x10-3V.

Dynamic analysis of nonlinear behaviour in inertial actuators

International Nuclear Information System (INIS)

Borgo, M Dal; Tehrani, M Ghandchi; Elliott, S J

2016-01-01

Inertial actuators are devices typically used to generate the control force on a vibrating structure. Generally, an inertial actuator comprises a proof-mass suspended in a magnetic field. The inertial force due to the moving mass is used to produce the secondary force needed to control the vibration of the primary structure. Inertial actuators can show nonlinear behaviour, such as stroke saturation when driven at high input voltages. If the input voltage is beyond their limit, they can hit the end stop of the actuator casing and saturate. In this paper, the force generated by an inertial actuator is measured experimentally and numerical simulations of a linear piecewise stiffness model are carried out and compared with the results of analytical methods. First, a numerical model for a symmetric bilinear stiffness is derived and a parametric study is carried out to investigate the change of the end stop stiffness. In addition, the variation of the amplitude of the excitation is considered and a comparison is made with the analytical solution using the harmonic balance method. Finally, experimental measurements are carried out and the results are compared with simulated data to establish the accuracy of the model. (paper)

Rapid prototyping prosthetic hand acting by a low-cost shape-memory-alloy actuator.

Science.gov (United States)

Soriano-Heras, Enrique; Blaya-Haro, Fernando; Molino, Carlos; de Agustín Del Burgo, José María

2018-06-01

The purpose of this article is to develop a new concept of modular and operative prosthetic hand based on rapid prototyping and a novel shape-memory-alloy (SMA) actuator, thus minimizing the manufacturing costs. An underactuated mechanism was needed for the design of the prosthesis to use only one input source. Taking into account the state of the art, an underactuated mechanism prosthetic hand was chosen so as to implement the modifications required for including the external SMA actuator. A modular design of a new prosthesis was developed which incorporated a novel SMA actuator for the index finger movement. The primary objective of the prosthesis is achieved, obtaining a modular and functional low-cost prosthesis based on additive manufacturing executed by a novel SMA actuator. The external SMA actuator provides a modular system which allows implementing it in different systems. This paper combines rapid prototyping and a novel SMA actuator to develop a new concept of modular and operative low-cost prosthetic hand.

Distributed force simulation for arbitrarily shaped IPMC actuators

International Nuclear Information System (INIS)

Martinez, M; Lumia, R

2013-01-01

This paper presents a simulation model that predicts the force output of arbitrarily shaped ionic polymer–metal composite (IPMC) actuators. Theoretical and experimental force measurements are compared for a triangular IPMC actuator with a tip length of 11 mm. The results show that the simulated tip force is within 80% of the experimentally determined value. Simulated electrical results for an artificial shark pectoral fin and a 7 mm × 17 mm actuator are also presented. In each case, the voltage is shown to decrease exponentially from the input point. The results of an ion migration simulation for a 180 μm cubic element of Nafion are presented for both a constant 2 V input and a 2 V 0.25 Hz sine signal. Finally, the simulated deformation of an IPMC shark fin is shown. (paper)

A Reconfiguration Scheme for Accommodating Actuator Failures in Multi-Input, Multi-Output Flight Control Systems

Science.gov (United States)

Siwakosit, W.; Hess, R. A.; Bacon, Bart (Technical Monitor); Burken, John (Technical Monitor)

2000-01-01

A multi-input, multi-output reconfigurable flight control system design utilizing a robust controller and an adaptive filter is presented. The robust control design consists of a reduced-order, linear dynamic inversion controller with an outer-loop compensation matrix derived from Quantitative Feedback Theory (QFT). A principle feature of the scheme is placement of the adaptive filter in series with the QFT compensator thus exploiting the inherent robustness of the nominal flight control system in the presence of plant uncertainties. An example of the scheme is presented in a pilot-in-the-loop computer simulation using a simplified model of the lateral-directional dynamics of the NASA F18 High Angle of Attack Research Vehicle (HARV) that included nonlinear anti-wind up logic and actuator limitations. Prediction of handling qualities and pilot-induced oscillation tendencies in the presence of these nonlinearities is included in the example.

Synthesis and Development of Gold Polypyrrole Actuator for Underwater Application

Science.gov (United States)

Panda, S. K.; Bandopadhya, D.

2018-02-01

Electro-active polymer (EAP) such as Polypyrrole has gained much attention in the category of functional materials for fabrication of both active actuator and sensor. Particularly, PPy actuator has shown potential in fluid medium application because of high strain, large bending displacement and work density. This paper focuses on developing a low cost active actuator promising in delivering high performance in underwater environment. The proposed Au-pyrrole actuator is synthesized by adopting the layer-by-layer electrochemical polymerization technique and is fabricated as strip actuator from aqueous solution of Pyrrole and NaDBS in room temperature. In the follow-up, topographical analysis has been carried out using SEM and FESEM instruments showing surface morphology and surface integrity of chemical components of the structure. Several experiments have been conducted under DC input voltage evaluating performance effectiveness such as underwater bending displacement and tip force etc. This is observed that the actuator exhibits quite similar stress profile as of natural muscle, endowed with high modulus makes them effective in working nearly 10,000 cycles underwater environment. In addition, the bending displacement up to 5.4 mm with a low input voltage 1.3 V makes the actuator suitable for underwater micro-robotics applications.

Iterative Learning Control of Hysteresis in Piezoelectric Actuators

Directory of Open Access Journals (Sweden)

Guilin Zhang

2014-01-01

input in hysteretic systems. In the analysis, the Prandtl-Ishlinskii model is utilized to capture the nonlinear behavior in piezoelectric actuators. Finally, we apply the control algorithm to an experimental piezoelectric actuator and conclude that the tracking error is reduced to 0.15% of the total displacement, which is approximately the noise level of the sensor measurement.

Detection and Identification of Loss of Efficiency Faults of Flight Actuators

Directory of Open Access Journals (Sweden)

Ossmann Daniel

2015-03-01

Full Text Available We propose linear parameter-varying (LPV model-based approaches to the synthesis of robust fault detection and diagnosis (FDD systems for loss of efficiency (LOE faults of flight actuators. The proposed methods are applicable to several types of parametric (or multiplicative LOE faults such as actuator disconnection, surface damage, actuator power loss or stall loads. For the detection of these parametric faults, advanced LPV-model detection techniques are proposed, which implicitly provide fault identification information. Fast detection of intermittent stall loads (seen as nuisances, rather than faults is important in enhancing the performance of various fault detection schemes dealing with large input signals. For this case, a dedicated fast identification algorithm is devised. The developed FDD systems are tested on a nonlinear actuator model which is implemented in a full nonlinear aircraft simulation model. This enables the validation of the FDD system’s detection and identification characteristics under realistic conditions.

Note: A novel rotary actuator driven by only one piezoelectric actuator.

Science.gov (United States)

Huang, Hu; Fu, Lu; Zhao, Hongwei; Shi, Chengli; Ren, Luquan; Li, Jianping; Qu, Han

2013-09-01

This paper presents a novel piezo-driven rotary actuator based on the parasitic motion principle. Output performances of the rotary actuator were tested and discussed. Experiment results indicate that using only one piezoelectric actuator and simple sawtooth wave control, the rotary actuator reaches the rotation velocity of about 20,097 μrad/s when the driving voltage is 100 V and the driving frequency is 90 Hz. The actuator can rotate stably with the minimum resolution of 0.7 μrad. This paper verifies feasibility of the parasitic motion principle for applications of rotary actuators, providing new design ideas for precision piezoelectric rotary actuators.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

Science.gov (United States)

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-01

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation.

Science.gov (United States)

Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

2016-04-15

Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

Implementasi Prototype Alat Uji Flight Control Actuator Pesawat Berbasis Mikrokontroller Arduino Uno

Directory of Open Access Journals (Sweden)

NANDANG TARYANA

2017-07-01

Full Text Available ABSTRAKFlight control system merupakan suatu sistem di pesawat udara yang digunakan untuk manuver dari satu kondisi terbang ke kondisi terbang lainnya. Alat uji flight control actuator pesawat ini dirancang berupa prototype yang dikendalikan dengan menggunakan mikrokontroller arduino uno, yang terdiri dari input dan output. Input tersebut adalah sensor load cell yang berfungsi untuk mengetahui beban yang diterima dari aktuator pesawat, serta input sensor ping berfungsi untuk mengetahui jarak ataupun sudut dari pergerakan aktuator pesawat. Sedangkan output yang dihasilkan berupa data dari hasil pembacaan sensor load cell dan sensor ping. Alat uji flight control sistem aktuator pesawat yang telah direalisasikan mampu menggerakkan 2 buah double acting cylinder untuk bekerja naik dan turun secara bergantian serta mampu menggerakkan motor servo dengan jarak pergerakkan 3 cm – 4 cm.Kata kunci: Flight control system, Arduino Uno, double acting cylinder, Sensor Ping, Load Cell, Motor ServoABSTRACTFlight control system is a system in which aircraft are used to maneuver from one condition to fly to other flight conditions. Testing instruments aircraft flight control actuator designed a prototype of which is controlled by using microcontroller arduino uno, which consists of input and output. The input is a load cell sensor that serves to determine the load received from aircraft actuators, as well as ping sensor input is used to determine the distance or angle of the aircraft actuator movement . While the output of the data from the load cell sensor readings and sensor ping . Test equipment aircraft flight control actuator system that has been realized is able to move two pieces of double acting cylinder to work up and down alternately and able to drive the servo motor with the movement distance of 3 cm – 4 cm . Keywords: Flight control system , Arduino Uno , double acting cylinder , Ping Sensor, Load Cell, Servo Motor 

Implementasi Prototype Alat Uji Flight Control Actuator Pesawat Berbasis Mikrokontroller Arduino Uno

Directory of Open Access Journals (Sweden)

NANDANG TARYANA

2018-02-01

Full Text Available ABSTRAK Flight control system merupakan suatu sistem di pesawat udara yang digunakan untuk manuver dari satu kondisi terbang ke kondisi terbang lainnya. Alat uji flight control actuator pesawat ini dirancang berupa prototype yang dikendalikan dengan menggunakan mikrokontroller arduino uno, yang terdiri dari input dan output. Input tersebut adalah sensor load cell yang berfungsi untuk mengetahui beban yang diterima dari aktuator pesawat, serta input sensor ping berfungsi untuk mengetahui jarak ataupun sudut dari pergerakan aktuator pesawat. Sedangkan output yang dihasilkan berupa data dari hasil pembacaan sensor load cell dan sensor ping. Alat uji flight control sistem aktuator pesawat yang telah direalisasikan mampu menggerakkan 2 buah double acting cylinder untuk bekerja naik dan turun secara bergantian serta mampu menggerakkan motor servo dengan jarak pergerakkan 3 cm – 4 cm. Kata kunci: Flight control system, Arduino Uno, double acting cylinder, Sensor Ping, Load Cell, Motor Servo ABSTRACT Flight control system is a system in which aircraft are used to maneuver from one condition to fly to other flight conditions. Testing instruments aircraft flight control actuator designed a prototype of which is controlled by using microcontroller arduino uno, which consists of input and output. The input is a load cell sensor that serves to determine the load received from aircraft actuators, as well as ping sensor input is used to determine the distance or angle of the aircraft actuator movement . While the output of the data from the load cell sensor readings and sensor ping . Test equipment aircraft flight control actuator system that has been realized is able to move two pieces of double acting cylinder to work up and down alternately and able to drive the servo motor with the movement distance of 3 cm – 4 cm . Keywords: Flight control system , Arduino Uno , double acting cylinder , Ping Sensor, Load Cell, Servo Motor

The static actuation of dielectric elastomer actuators: how does pre-stretch improve actuation?

International Nuclear Information System (INIS)

Kofod, Guggi

2008-01-01

It has previously been shown that providing dielectric elastomer actuators with a level of pre-stretch can improve properties such as breakdown strength, actuation strain and efficiency. The actuation in such actuators depends on an interplay between the highly nonlinear hyperelastic stress-strain behaviour with the electrostatic Maxwell's stress; however, the direct effects of pre-stretch on the electromechanical coupling have still not been investigated in detail. We compare several experimental results found in the literature on the hyperelastic parameters of the Ogden model for the commonly used material VHB 4910, and introduce a more detailed and thus more accurate fit to a previous uniaxial stress-strain experiment. Electrostatic actuation models for a pure shear cuboid dielectric elastomer actuator with pre-stretch are introduced, for both intensive and extensive variables. For both intensive and extensive variables the constant strain (blocked stress or force) as well as the actuation strain is presented. It is shown how in the particular case of isotropic amorphous elastomers the pre-stretch does not affect the electromechanical coupling directly, and that the enhancement in actuation strain due to pre-stretch occurs through the alteration of the geometrical dimensions of the actuator. Also, the presence of the optimum load is explained as being due to the plateau region in the force-stretch curve, and it is shown that pre-stretch is not able to affect its position. Finally, it is shown how the simplified Ogden fit leads to entirely different conclusions for actuation strain in terms of extensive variables as does the detailed fit, emphasizing the importance of employing accurate hyperelastic models for the stress-stretch behaviour of the elastomer.

3D printed soft parallel actuator

Science.gov (United States)

Zolfagharian, Ali; Kouzani, Abbas Z.; Khoo, Sui Yang; Noshadi, Amin; Kaynak, Akif

2018-04-01

This paper presents a 3-dimensional (3D) printed soft parallel contactless actuator for the first time. The actuator involves an electro-responsive parallel mechanism made of two segments namely active chain and passive chain both 3D printed. The active chain is attached to the ground from one end and constitutes two actuator links made of responsive hydrogel. The passive chain, on the other hand, is attached to the active chain from one end and consists of two rigid links made of polymer. The actuator links are printed using an extrusion-based 3D-Bioplotter with polyelectrolyte hydrogel as printer ink. The rigid links are also printed by a 3D fused deposition modelling (FDM) printer with acrylonitrile butadiene styrene (ABS) as print material. The kinematics model of the soft parallel actuator is derived via transformation matrices notations to simulate and determine the workspace of the actuator. The printed soft parallel actuator is then immersed into NaOH solution with specific voltage applied to it via two contactless electrodes. The experimental data is then collected and used to develop a parametric model to estimate the end-effector position and regulate kinematics model in response to specific input voltage over time. It is observed that the electroactive actuator demonstrates expected behaviour according to the simulation of its kinematics model. The use of 3D printing for the fabrication of parallel soft actuators opens a new chapter in manufacturing sophisticated soft actuators with high dexterity and mechanical robustness for biomedical applications such as cell manipulation and drug release.

Robust Nonlinear Regulation of Limit Cycle Oscillations in UAVs Using Synthetic Jet Actuators

Directory of Open Access Journals (Sweden)

Natalie Ramos Pedroza

2014-09-01

Full Text Available In this paper, a synthetic jet actuators (SJA-based nonlinear robust controller is developed, which is capable of completely suppressing limit cycle oscillations (LCO in UAV systems with parametric uncertainty in the SJA dynamics and unmodeled external disturbances. Specifically, the control law compensates for uncertainty in an input gain matrix, which results from the unknown airflow dynamics generated by the SJA. Challenges in the control design include compensation for input-multiplicative parametric uncertainty in the actuator dynamic model. The result was achieved via innovative algebraic manipulation in the error system development, along with a Lyapunov-based robust control law. A rigorous Lyapunov-based stability analysis is utilized to prove asymptotic LCO suppression, considering a detailed dynamic model of the pitching and plunging dynamics. Numerical simulation results are provided to demonstrate the robustness and practical performance of the proposed control law.

Theoretical and experimental study on active sound transmission control based on single structural mode actuation using point force actuators.

Science.gov (United States)

Sanada, Akira; Tanaka, Nobuo

2012-08-01

This study deals with the feedforward active control of sound transmission through a simply supported rectangular panel using vibration actuators. The control effect largely depends on the excitation method, including the number and locations of actuators. In order to obtain a large control effect at low frequencies over a wide frequency, an active transmission control method based on single structural mode actuation is proposed. Then, with the goal of examining the feasibility of the proposed method, the (1, 3) mode is selected as the target mode and a modal actuation method in combination with six point force actuators is considered. Assuming that a single input single output feedforward control is used, sound transmission in the case minimizing the transmitted sound power is calculated for some actuation methods. Simulation results showed that the (1, 3) modal actuation is globally effective at reducing the sound transmission by more than 10 dB in the low-frequency range for both normal and oblique incidences. Finally, experimental results also showed that a large reduction could be achieved in the low-frequency range, which proves the validity and feasibility of the proposed method.

Optimal Sensor and Actuator Location for Unstable Systems

DEFF Research Database (Denmark)

Shaker, Hamid Reza; Tahavori, Maryamsadat

2013-01-01

on the processes. Dually the problem of placing actuators on the processes is equally important. In this paper, the problem of determining optimal sensor and actuator locations for the linear systems is addressed. The problem of the sensor locations is viewed as the problem of maximizing the output energy...... generated by a given state and for the actuator locations is viewed as the problem of minimizing the input energy required to reach a given state. Such design problems occur in many applications, and therefore have been studied extensively. Unfortunately, the results in this context, which have been...

A practical multilayered conducting polymer actuator with scalable work output

International Nuclear Information System (INIS)

Ikushima, Kimiya; John, Stephen; Yokoyama, Kazuo; Nagamitsu, Sachio

2009-01-01

Household assistance robots are expected to become more prominent in the future and will require inherently safe design. Conducting polymer-based artificial muscle actuators are one potential option for achieving this safety, as they are flexible, lightweight and can be driven using low input voltages, unlike electromagnetic motors; however, practical implementation also requires a scalable structure and stability in air. In this paper we propose and practically implement a multilayer conducting polymer actuator which could achieve these targets using polypyrrole film and ionic liquid-soaked separators. The practical work density of a nine-layer multilayer actuator was 1.4 kJ m −3 at 0.5 Hz, when the volumes of the electrolyte and counter electrodes were included, which approaches the performance of mammalian muscle. To achieve air stability, we analyzed the effect of air-stable ionic liquid gels on actuator displacement using finite element simulation and it was found that the majority of strain could be retained when the elastic modulus of the gel was kept below 3 kPa. As a result of this work, we have shown that multilayered conducting polymer actuators are a feasible idea for household robotics, as they provide a substantial practical work density in a compact structure and can be easily scaled as required

Output Force Enhancement of Scratch Drive Actuator in Low-Voltage Region by Using Flexible Joint

Directory of Open Access Journals (Sweden)

Shawn CHEN

2010-04-01

Full Text Available Here a low-voltage scratch drive actuator (LVSDA is proposed by incorporating flexible joint into the conventional SDA to improve performance in low-voltage region. Experimental results show that, at the same total plate length of 80 mm and width of 65 mm, the proposed LVSDA can be actuated as low as 40 V, much lower than 80 V, the minimum required input voltage of the conventional SDA. From finite element analysis by CosmosWorks, yielding effect is found to be a critical factor. Before yielding, LVSDA can provide better performance than SDA at the same input voltage. However, the yielding stress in flexible joint would limit the achievable maximum output force in high-voltage region. By varying joint length, width, or location, LVSDA is shown to be operated in low-voltage region where the conventional SDA can not be operated, and can still provide comparable performance as SDA in high-voltage region.

Compact electrostatic comb actuator

Science.gov (United States)

Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

2000-01-01

A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

Three-dimensional static shape control analysis of composite plates using distributed piezoelectric actuators

International Nuclear Information System (INIS)

Shaik Dawood, M S I; Iannucci, L; Greenhalgh, E S

2008-01-01

In this work, based on a linear piezoelectric constitutive model, a three-dimensional finite element code using an eight-node brick element that includes the anisotropic and coupled field effects of piezoelectric actuators has been developed for the static shape control analysis of fibre reinforced composite laminates. The code was used to study voltage sensing and actuation capabilities of piezoelectric actuators on composite laminates. The required input voltages to the actuators in order to achieve a specified structural shape were determined using a weighted shape control method. The code was validated using two test cases obtained from the literature. The results were found to show good correlation for voltage actuation. However, since determining input voltages to achieve the desired structural shape is a type of inverse problem, there are no explicit solutions and hence the results obtained from the present model were not similar to those reported in the literature. The second validation also suggests that the anisotropic and coupled field effects of the piezoelectric actuators cannot be neglected as this has been shown to underestimate the required control voltages. The effects of different lamination angles, boundary conditions, plate length-to-thickness ratios and actuator dimensions on the control voltages have also been reported

Control of soft machines using actuators operated by a Braille display.

Science.gov (United States)

Mosadegh, Bobak; Mazzeo, Aaron D; Shepherd, Robert F; Morin, Stephen A; Gupta, Unmukt; Sani, Idin Zhalehdoust; Lai, David; Takayama, Shuichi; Whitesides, George M

2014-01-07

One strategy for actuating soft machines (e.g., tentacles, grippers, and simple walkers) uses pneumatic inflation of networks of small channels in an elastomeric material. Although the management of a few pneumatic inputs and valves to control pressurized gas is straightforward, the fabrication and operation of manifolds containing many (>50) independent valves is an unsolved problem. Complex pneumatic manifolds-often built for a single purpose-are not easily reconfigured to accommodate the specific inputs (i.e., multiplexing of many fluids, ranges of pressures, and changes in flow rates) required by pneumatic systems. This paper describes a pneumatic manifold comprising a computer-controlled Braille display and a micropneumatic device. The Braille display provides a compact array of 64 piezoelectric actuators that actively close and open elastomeric valves of a micropneumatic device to route pressurized gas within the manifold. The positioning and geometries of the valves and channels in the micropneumatic device dictate the functionality of the pneumatic manifold, and the use of multi-layer soft lithography permits the fabrication of networks in a wide range of configurations with many possible functions. Simply exchanging micropneumatic devices of different designs enables rapid reconfiguration of the pneumatic manifold. As a proof of principle, a pneumatic manifold controlled a soft machine containing 32 independent actuators to move a ball above a flat surface.

Robust Redundant Input Reliable Tracking Control for Omnidirectional Rehabilitative Training Walker

Directory of Open Access Journals (Sweden)

Ping Sun

2014-01-01

Full Text Available The problem of robust reliable tracking control on the omnidirectional rehabilitative training walker is examined. The new nonlinear redundant input method is proposed when one wheel actuator fault occurs. The aim of the study is to design an asymptotically stable controller that can guarantee the safety of the user and ensure tracking on a training path planned by a physical therapist. The redundant degrees of freedom safety control and the asymptotically zero state detectable concept of the walker are presented, the model of redundant degree is constructed, and the property of center of gravity constant shift is obtained. A controller that can satisfy asymptotic stability is obtained using a common Lyapunov function for admissible uncertainties resulting from an actuator fault. Simulation results confirm the effectiveness of the proposed method and verify that the walker can provide safe sequential motion when one wheel actuator is at fault.

Self-Latching Piezocomposite Actuator

Science.gov (United States)

Wilkie, William K. (Inventor); Bryant, Robert G. (Inventor); Lynch, Christopher S. (Inventor)

2017-01-01

A self-latching piezocomposite actuator includes a plurality of shape memory ceramic fibers. The actuator can be latched by applying an electrical field to the shape memory ceramic fibers. The actuator remains in a latched state/shape after the electrical field is no longer present. A reverse polarity electric field may be applied to reset the actuator to its unlatched state/shape. Applied electric fields may be utilized to provide a plurality of latch states between the latched and unlatched states of the actuator. The self-latching piezocomposite actuator can be used for active/adaptive airfoils having variable camber, trim tabs, active/deformable engine inlets, adaptive or adjustable vortex generators, active optical components such as mirrors that change shapes, and other morphing structures.

Stiffness control of a nylon twisted coiled actuator for use in mechatronic rehabilitation devices.

Science.gov (United States)

Edmonds, Brandon P R; Trejos, Ana Luisa

2017-07-01

Mechatronic rehabilitation devices, especially wearables, have been researched extensively and proven to be promising additions to physical therapy, but most designs utilize traditional actuators providing unnatural, robot-like movements. Therefore, many researchers have focused on the development of actuators that mimic biological properties to provide patients with improved results, safety, and comfort. Recently, a twisted-coiled actuator (TCA) made from nylon thread has been found to possess many of these important properties when heated, such as variable stiffness, flexibility, and high power density. So far, TCAs have been characterized in controlled environments to define their fundamental properties under simple loading configurations. However, for an actuator like this to be implemented in a biomimetic design such as an exoskeleton, it needs to be characterized and controlled as a biological muscle. One major control law that natural muscles exhibit is stiffness control, allowing humans to passively avoid injury from external forces, or move the limbs in a controlled or high impact motion. This type of control is created by the antagonistic muscle arrangement. In this paper, an antagonistic apparatus was developed to model the TCAs from a biological standpoint, the stiffness was characterized with respect to the TCA temperature, and a fully functional stiffness and position controller was implemented with an incorporated TCA thermal model. The stiffness was found to have a linear relationship to the TCA temperatures (R 2 =0.95). The controller performed with a stiffness accuracy of 98.95% and a position accuracy of 92.7%. A final trial with varying continuous position input and varying stepped stiffness input exhibited position control with R 2 =0.9638.

Design of Rotating Moving-Magnet-Type VCM Actuator for Miniaturized Mobile Robot

Energy Technology Data Exchange (ETDEWEB)

Shin, Bu Hyun [Hanbat Nat' l Univ., Daejeon (Korea, Republic of); Lee, Seungyop [Sogana Univ., Seoul (Korea, Republic of); Lee, Kyungmin [Korean Intellectual Property Office, Seoul (Korea, Republic of); Oh, Dongho [Chungnam Nat' l Univ., Daejeon (Korea, Republic of)

2013-12-15

A voice coil actuator with a rotating moving magnet has been developed for a miniaturized mobile robot. The actuator has simple structure comprising a magnet, a coil, and a yoke. Actuator performance is predicted using a linearized theoretical model, and dynamic performance based on the air-gap between the magnet and the coil is predicted using motor constant and restoring constant obtained through finite element simulations. The theoretical model was verified using a prototype with 60 Hz resonance and 80 Hz bandwidth. We found that an input of 1.5 V can make the actuator rotate by 20 .deg. statically. The driving configuration of the proposed actuator can be simplified because of its implementation of open-loop control.

Hysteresis compensation for piezoelectric actuators in single-point diamond turning

Science.gov (United States)

Wang, Haifeng; Hu, Dejin; Wan, Daping; Liu, Hongbin

2006-02-01

In recent years, interests have been growing for fast tool servo (FTS) systems to increase the capability of existing single-point diamond turning machines. Although piezoelectric actuator is the most universal base of FTS system due to its high stiffness, accuracy and bandwidth, nonlinearity in piezoceramics limits both the static and dynamic performance of piezoelectric-actuated control systems evidently. To compensate the nonlinear hysteresis behavior of piezoelectric actuators, a hybrid model coupled with Preisach model and feedforward neural network (FNN) has been described. Since the training of FNN does not require a special calibration sequence, it is possible for on-line identification and real-time implementation with general operating data of a specific piezoelectric actuator. To describe the rate dependent behavior of piezoelectric actuators, a hybrid dynamic model was developed to predict the response of piezoelectric actuators in a wider range of input frequency. Experimental results show that a maximal error of less than 3% was accomplished by this dynamic model.

Mechanical behaviour of bending bucky-gel actuators and its representation

International Nuclear Information System (INIS)

Kruusamäe, Karl; Mukai, Ken; Sugino, Takushi; Asaka, Kinji

2014-01-01

Bucky-gel actuators are ionic electromechanically active materials that bend in response to a low-voltage excitation. While bending actuators may offer new approaches in engineering solutions, the characterization of bending poses many challenges in comparison to conventional rotary motion. It is often desired to reduce the bending behaviour to a single parameter, which may lead to the loss of accuracy in modelling. A high-speed laser profilometer is utilized to characterize the bending response of different bucky-gel actuators at their full length and to critically compare the applicability of existing representation tools for bending. The best analytical representation of the bending of a bucky-gel actuator is found to be in the form of a power function. It is also observed that, along the length of the actuator, sections closer to the electrical input clamp exhibit back-relaxation (a common drawback for bending ionic actuators) already when the far end of the bending strip is still in forward motion. (paper)

Safety actuator of the Cabri reactor as a function of its power and cooling fluid flow rate

International Nuclear Information System (INIS)

Bertrand, Jean; Da Costa Vieira, David; Tattegrain, Alain

1969-04-01

This report present a device which is to provide a stop command to the Cabri reactor when the rate of its power to the cooling fluid rate reaches a value determined with respect to water temperature in the circuit. The stop command is delivered by an actuator which opens a relay contact when the power reaches a specific value. The authors present the device, its characteristics, and principle. They also present the different amplifier circuits, the input and output circuits (flow rate input, temperature input, and output circuit), the energy supply, and the various adjustments

Digital Actuator Technology

Energy Technology Data Exchange (ETDEWEB)

Ken Thomas; Ted Quinn; Jerry Mauck; Richard Bockhorst

2014-09-01

There are significant developments underway in new types of actuators for power plant active components. Many of these make use of digital technology to provide a wide array of benefits in performance of the actuators and in reduced burden to maintain them. These new product offerings have gained considerable acceptance in use in process plants. In addition, they have been used in conventional power generation very successfully. This technology has been proven to deliver the benefits promised and substantiate the claims of improved performance. The nuclear industry has been reluctant to incorporate digital actuator technology into nuclear plant designs due to concerns due to a number of concerns. These could be summarized as cost, regulatory uncertainty, and a certain comfort factor with legacy analog technology. The replacement opportunity for these types of components represents a decision point for whether to invest in more modern technology that would provide superior operational and maintenance benefits. Yet, the application of digital technology has been problematic for the nuclear industry, due to qualification and regulatory issues. With some notable exceptions, the result has been a continuing reluctance to undertake the risks and uncertainties of implementing digital actuator technology when replacement opportunities present themselves. Rather, utilities would typically prefer to accept the performance limitations of the legacy analog actuator technologies to avoid impacts to project costs and schedules. The purpose of this report is to demonstrate that the benefits of digital actuator technology can be significant in terms of plant performance and that it is worthwhile to address the barriers currently holding back the widespread development and use of this technology. It addresses two important objectives in pursuit of the beneficial use of digital actuator technology for nuclear power plants: 1. To demonstrate the benefits of digital actuator

Control of a perturbed under-actuated mechanical system

KAUST Repository

Zayane, Chadia; Laleg-Kirati, Taous-Meriem; Chemori, Ahmed

2015-01-01

In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed

Resolving Actuator Redundancy - Control Allocation vs. Linear Quadratic Control

OpenAIRE

Härkegård, Ola

2004-01-01

When designing control laws for systems with more inputs than controlled variables, one issue to consider is how to deal with actuator redundancy. Two tools for distributing the control effort among a redundant set of actuators are control allocation and linear quadratic control design. In this paper, we investigate the relationship between these two design tools when a quadratic performance index is used for control allocation. We show that for a particular class of linear systems, they give...

Delayed system control in presence of actuator saturation

Directory of Open Access Journals (Sweden)

A. Mahjoub

2014-09-01

Full Text Available The paper is introducing a new design method for systems’ controllers with input delay and actuator saturations and focuses on how to force the system output to track a reference input not necessarily saturation-compatible. We propose a new norm based on the way we quantify tracking performance as a function of saturation errors found using the same norm. The newly defined norm is related to signal average power making possible to account for most common reference signals e.g. step, periodic. It is formally shown that, whatever the reference shape and amplitude, the achievable tracking quality is determined by a well defined reference tracking mismatch error. This latter depends on the reference rate and its compatibility with the actuator saturation constraint. In fact, asymptotic output-reference tracking is achieved in the presence of constraint-compatible step-like references.

Fault-tolerant rotary actuator

Science.gov (United States)

Tesar, Delbert

2006-10-17

A fault-tolerant actuator module, in a single containment shell, containing two actuator subsystems that are either asymmetrically or symmetrically laid out is provided. Fault tolerance in the actuators of the present invention is achieved by the employment of dual sets of equal resources. Dual resources are integrated into single modules, with each having the external appearance and functionality of a single set of resources.

Tracking Control of Hysteretic Piezoelectric Actuator using Adaptive Rate-Dependent Controller.

Science.gov (United States)

Tan, U-Xuan; Latt, Win Tun; Widjaja, Ferdinan; Shee, Cheng Yap; Riviere, Cameron N; Ang, Wei Tech

2009-03-16

With the increasing popularity of actuators involving smart materials like piezoelectric, control of such materials becomes important. The existence of the inherent hysteretic behavior hinders the tracking accuracy of the actuators. To make matters worse, the hysteretic behavior changes with rate. One of the suggested ways is to have a feedforward controller to linearize the relationship between the input and output. Thus, the hysteretic behavior of the actuator must first be modeled by sensing the relationship between the input voltage and output displacement. Unfortunately, the hysteretic behavior is dependent on individual actuator and also environmental conditions like temperature. It is troublesome and costly to model the hysteresis regularly. In addition, the hysteretic behavior of the actuators also changes with age. Most literature model the actuator using a cascade of rate-independent hysteresis operators and a dynamical system. However, the inertial dynamics of the structure is not the only contributing factor. A complete model will be complex. Thus, based on the studies done on the phenomenological hysteretic behavior with rate, this paper proposes an adaptive rate-dependent feedforward controller with Prandtl-Ishlinskii (PI) hysteresis operators for piezoelectric actuators. This adaptive controller is achieved by adapting the coefficients to manipulate the weights of the play operators. Actual experiments are conducted to demonstrate the effectiveness of the adaptive controller. The main contribution of this paper is its ability to perform tracking control of non-periodic motion and is illustrated with the tracking control ability of a couple of different non-periodic waveforms which were created by passing random numbers through a low pass filter with a cutoff frequency of 20Hz.

A two-stage approach for managing actuators redundancy and its application to fault tolerant flight control

Directory of Open Access Journals (Sweden)

Zhong Lunlong

2015-04-01

Full Text Available In safety-critical systems such as transportation aircraft, redundancy of actuators is introduced to improve fault tolerance. How to make the best use of remaining actuators to allow the system to continue achieving a desired operation in the presence of some actuators failures is the main subject of this paper. Considering that many dynamical systems, including flight dynamics of a transportation aircraft, can be expressed as an input affine nonlinear system, a new state representation is adopted here where the output dynamics are related with virtual inputs associated with the intended operation. This representation, as well as the distribution matrix associated with the effectiveness of the remaining operational actuators, allows us to define different levels of fault tolerant governability with respect to actuators’ failures. Then, a two-stage control approach is developed, leading first to the inversion of the output dynamics to get nominal values for the virtual inputs and then to the solution of a linear quadratic (LQ problem to compute the solicitation of each operational actuator. The proposed approach is applied to the control of a transportation aircraft which performs a stabilized roll maneuver while a partial failure appears. Two fault scenarios are considered and the resulting performance of the proposed approach is displayed and discussed.

A biomimetic jellyfish robot based on ionic polymer metal composite actuators

International Nuclear Information System (INIS)

Yeom, Sung-Weon; Oh, Il-Kwon

2009-01-01

A biomimetic jellyfish robot based on ionic polymer metal composite actuators was fabricated and activated to mimic real locomotive behavior with pulse and recovery processes. To imitate the curved shape of the jellyfish, a thermal treatment was applied to obtain a permanent initial deformation of a hemispherical form. The bio-inspired input signal was generated for mimicking real locomotion of the jellyfish. The vertical floating displacement and the thrust force of the biomimetic jellyfish robot under various input signals were measured and compared. The present results show that the bio-inspired electrical input signal with pulse-recovery process generates much higher floating velocity of the biomimetic jellyfish robot in comparison with pure sinusoidal excitations. The curved shape of the IPMC actuator through thermal treatments can be successfully applied to mimic the real biomimetic robots with smooth curves

Space Shuttle Rudder Speed Brake Actuator-A Case Study Probabilistic Fatigue Life and Reliability Analysis

Science.gov (United States)

Oswald, Fred B.; Savage, Michael; Zaretsky, Erwin V.

2015-01-01

The U.S. Space Shuttle fleet was originally intended to have a life of 100 flights for each vehicle, lasting over a 10-year period, with minimal scheduled maintenance or inspection. The first space shuttle flight was that of the Space Shuttle Columbia (OV-102), launched April 12, 1981. The disaster that destroyed Columbia occurred on its 28th flight, February 1, 2003, nearly 22 years after its first launch. In order to minimize risk of losing another Space Shuttle, a probabilistic life and reliability analysis was conducted for the Space Shuttle rudder/speed brake actuators to determine the number of flights the actuators could sustain. A life and reliability assessment of the actuator gears was performed in two stages: a contact stress fatigue model and a gear tooth bending fatigue model. For the contact stress analysis, the Lundberg-Palmgren bearing life theory was expanded to include gear-surface pitting for the actuator as a system. The mission spectrum of the Space Shuttle rudder/speed brake actuator was combined into equivalent effective hinge moment loads including an actuator input preload for the contact stress fatigue and tooth bending fatigue models. Gear system reliabilities are reported for both models and their combination. Reliability of the actuator bearings was analyzed separately, based on data provided by the actuator manufacturer. As a result of the analysis, the reliability of one half of a single actuator was calculated to be 98.6 percent for 12 flights. Accordingly, each actuator was subsequently limited to 12 flights before removal from service in the Space Shuttle.

Elastic Cube Actuator with Six Degrees of Freedom Output

Directory of Open Access Journals (Sweden)

Pengchuan Wang

2015-09-01

Full Text Available Unlike conventional rigid actuators, soft robotic technologies possess inherent compliance, so they can stretch and twist along every axis without the need for articulated joints. This compliance is exploited here using dielectric elastomer membranes to develop a novel six degrees of freedom (6-DOF polymer actuator that unifies ordinarily separate components into a simple cubic structure. This cube actuator design incorporates elastic dielectric elastomer membranes on four faces which are coupled by a cross-shaped end effector. The inherent elasticity of each membrane greatly reduces kinematic constraint and enables a 6-DOF actuation output to be produced via the end effector. An electro-mechanical model of the cube actuator is presented that captures the non-linear hyperelastic behaviour of the active membranes. It is demonstrated that the model accurately predicts actuator displacement and blocking moment for a range of input voltages. Experimental testing of a prototype 60 mm device demonstrates 6-DOF operation. The prototype produces maximum linear and rotational displacements of ±2.6 mm (±4.3% and ±4.8° respectively and a maximum blocking moment of ±76 mNm. The capacity for full 6-DOF actuation from a compact, readily scalable and easily fabricated polymeric package enables implementation in a range of mechatronics and robotics applications.

Mechanical stretching effect on the actuator performance of cellulose electroactive paper

International Nuclear Information System (INIS)

Kim, Jung-Hwan; Yun, Ki-Ju; Kim, Joo-Hyung; Kim, Jaehwan

2009-01-01

The mechanical stretching effect on the actuating performance of electroactive cellulose paper (EAPap) was studied. A lattice elongation of cellulose fibrils due to in-plane tensile stress along the stretching direction was observed by the x-ray diffraction method. The shrinkage of the fibril diameter as a function of stretching ratio was confirmed by surface and cross-sectional images. While the actuator performance in terms of bending displacement decreased as the stretching ratio increased, the resonance frequency linearly increased as the stretching ratio increased, which was compared with the theoretical frequency data found from a cantilever beam model. The actuator efficiency was evaluated from the electrical input power consumption and the mechanical output power of an EAPap actuator. It was revealed that the stretching process increased the electro-mechanical efficiency of the EAPap actuator. The mechanism of the influence of the stretching effect on the performance of an EAPap actuator is discussed

A eutectic-alloy-infused soft actuator with sensing, tunable degrees of freedom, and stiffness properties

Science.gov (United States)

Hao, Yufei; Wang, Tianmiao; Xie, Zhexin; Sun, Wenguang; Liu, Zemin; Fang, Xi; Yang, Minxuan; Wen, Li

2018-02-01

This paper presents a soft actuator embedded with two types of eutectic alloys which enable sensing, tunable mechanical degrees of freedom (DOF), and variable stiffness properties. To modulate the stiffness of the actuator, we embedded a low melting point alloy (LMPA) in the bottom portion of the soft actuator. Different sections of the LMPA could be selectively melted by the Ni-Cr wires twined underneath. To acquire the curvature information, EGaIn (eutectic gallium indium) was infused into a microchannel surrounding the chambers of the soft actuator. Systematic experiments were performed to characterize the stiffness, tunable DOF, and sensing the bending curvature. We found that the average bending force and elasticity modulus could be increased about 35 and 4000 times, respectively, with the LMPA in a solid state. The entire LMPA could be melted from a solid to a liquid state within 12 s. In particular, up to six different motion patterns could be achieved under each pneumatic pressure of the soft actuator. Furthermore, the kinematics of the actuator under different motion patterns could be obtained by a mathematical model whose input was provided by the EGaIn sensor. For demonstration purposes, a two-fingered gripper was fabricated to grasp various objects by adjusting the DOF and mechanical stiffness.

Development of DBD plasma actuators: The double encapsulated electrode

Science.gov (United States)

Erfani, Rasool; Zare-Behtash, Hossein; Hale, Craig; Kontis, Konstantinos

2015-04-01

Plasma actuators are electrical devices that generate a wall bounded jet without the use of any moving parts. For aerodynamic applications they can be used as flow control devices to delay separation and augment lift on a wing. The standard plasma actuator consists of a single encapsulated (ground) electrode. The aim of this project is to investigate the effect of varying the number and distribution of encapsulated electrodes in the dielectric layer. Utilising a transformer cascade, a variety of input voltages are studied for their effect. In the quiescent environment of a Faraday cage the velocity flow field is recorded using particle image velocimetry. Through understanding of the mechanisms involved in producing the wall jet and the importance of the encapsulated electrode a novel actuator design is proposed. The actuator design distributes the encapsulated electrode throughout the dielectric layer. The experiments have shown that actuators with a shallow initial encapsulated electrode induce velocities greater than the baseline case at the same voltage. Actuators with a deep initial encapsulated electrode are able to induce the highest velocities as they can operate at higher voltages without breakdown of the dielectric.

Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control

Directory of Open Access Journals (Sweden)

Jhih-Hong Lin

2016-08-01

Full Text Available Magnetic shape memory (MSM alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control.

Science.gov (United States)

Lin, Jhih-Hong; Chiang, Mao-Hsiung

2016-08-25

Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

A high resolution pneumatic stepping actuator for harsh reactor environments

Science.gov (United States)

Tippetts, Thomas B.; Evans, Paul S.; Riffle, George K.

1993-01-01

A reactivity control actuator for a high-power density nuclear propulsion reactor must be installed in close proximity to the reactor core. The energy input from radiation to the actuator structure could exceed hundreds of W/cc unless low-cross section, low-absorptivity materials are chosen. Also, for post-test handling and subsequent storage, materials should not be used that are activated into long half-life isotopes. Pneumatic actuators can be constructed from various reactor-compatible materials, but conventional pneumatic piston actuators generally lack the stiffness required for high resolution reactivity control unless electrical position sensors and compensated electronic control systems are used. To overcome these limitations, a pneumatic actuator is under development that positions an output shaft in response to a series of pneumatic pulses, comprising a pneumatic analog of an electrical stepping motor. The pneumatic pulses are generated remotely, beyond the strong radiation environment, and transmitted to the actuator through tubing. The mechanically simple actuator uses a nutating gear harmonic drive to convert motion of small pistons directly to high-resolution angular motion of the output shaft. The digital nature of this actuator is suitable for various reactor control algorithms but is especially compatible with the three bean salad algorithm discussed by Ball et al. (1991).

Modeling and Control for Giant Magnetostrictive Actuators with Rate-Dependent Hysteresis

Directory of Open Access Journals (Sweden)

Ping Liu

2013-01-01

Full Text Available The rate-dependent hysteresis in giant magnetostrictive materials is a major impediment to the application of such material in actuators. In this paper, a relevance vector machine (RVM model is proposed for describing the hysteresis nonlinearity under varying input current. It is possible to construct a unique dynamic model in a given rate range for a rate-dependent hysteresis system using the sinusoidal scanning signals as the training set input signal. Subsequently, a proportional integral derivative (PID control scheme combined with a feedforward compensation is implemented on a giant magnetostrictive actuator (GMA for real-time precise trajectory tracking. Simulations and experiments both verify the effectiveness and the practicality of the proposed modeling and control methods.

Adaptive neuro-fuzzy control of ionic polymer metal composite actuators

International Nuclear Information System (INIS)

Thinh, Nguyen Truong; Yang, Young-Soo; Oh, Il-Kwon

2009-01-01

An adaptive neuro-fuzzy controller was newly designed to overcome the degradation of the actuation performance of ionic polymer metal composite actuators that show highly nonlinear responses such as a straightening-back problem under a step excitation. An adaptive control algorithm with the merits of fuzzy logic and neural networks was applied for controlling the tip displacement of the ionic polymer metal composite actuators. The reference and actual displacements and the change of the error with the electrical inputs were recorded to generate the training data. These data were used for training the adaptive neuro-fuzzy controller to find the membership functions in the fuzzy control algorithm. Software simulation and real-time experiments were conducted by using the Simulink and dSPACE environments. Present results show that the current adaptive neuro-fuzzy controller can be successfully applied to the reliable control of the ionic polymer metal composite actuator for which the performance degrades under long-time actuation

A light writable microfluidic "flash memory": optically addressed actuator array with latched operation for microfluidic applications.

Science.gov (United States)

Hua, Zhishan; Pal, Rohit; Srivannavit, Onnop; Burns, Mark A; Gulari, Erdogan

2008-03-01

This paper presents a novel optically addressed microactuator array (microfluidic "flash memory") with latched operation. Analogous to the address-data bus mediated memory address protocol in electronics, the microactuator array consists of individual phase-change based actuators addressed by localized heating through focused light patterns (address bus), which can be provided by a modified projector or high power laser pointer. A common pressure manifold (data bus) for the entire array is used to generate large deflections of the phase change actuators in the molten phase. The use of phase change material as the working media enables latched operation of the actuator array. After the initial light "writing" during which the phase is temporarily changed to molten, the actuated status is self-maintained by the solid phase of the actuator without power and pressure inputs. The microfluidic flash memory can be re-configured by a new light illumination pattern and common pressure signal. The proposed approach can achieve actuation of arbitrary units in a large-scale array without the need for complex external equipment such as solenoid valves and electrical modules, which leads to significantly simplified system implementation and compact system size. The proposed work therefore provides a flexible, energy-efficient, and low cost multiplexing solution for microfluidic applications based on physical displacements. As an example, the use of the latched microactuator array as "normally closed" or "normally open" microvalves is demonstrated. The phase-change wax is fully encapsulated and thus immune from contamination issues in fluidic environments.

Modelling and control of a nonlinear magnetostrictive actuator system

Science.gov (United States)

Ramli, M. H. M.; Majeed, A. P. P. Abdul; Anuar, M. A. M.; Mohamed, Z.

2018-04-01

This paper explores the implementation of a feedforward control method to a nonlinear control system, in particular, Magnetostrictive Actuators (MA) that has excellent properties of energy conversion between the mechanical and magnetic form through magnetostriction effects which could be used in actuating and sensing application. MA is known to exhibit hysteresis behaviour and it is rate dependent (the level of hysteresis depends closely on the rate of input excitation frequency). This is, nonetheless, an undesirable behaviour and has to be eliminated in realising high precision application. The MA is modelled by a phenomenological modelling approach via Prandtl-Ishlinskii (P-I) operator to characterise the hysteresis nonlinearities. A feedforward control strategy is designed and implemented to linearize and eliminate the hysteresis by model inversion. The results show that the P-I operator has the capability to model the hysteretic nonlinearity of MA with an acceptable accuracy. Furthermore, the proposed control scheme has demonstrated to be effective in providing superior trajectory tracking.

Levitating Micro-Actuators: A Review

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Kirill V. Poletkin

2018-04-01

Full Text Available Through remote forces, levitating micro-actuators completely eliminate mechanical attachment between the stationary and moving parts of a micro-actuator, thus providing a fundamental solution to overcoming the domination of friction over inertial forces at the micro-scale. Eliminating the usual mechanical constraints promises micro-actuators with increased operational capabilities and low dissipation energy. Further reduction of friction and hence dissipation by means of vacuum leads to dramatic increases of performance when compared to mechanically tethered counterparts. In order to efficiently employ the benefits provided by levitation, micro-actuators are classified according to their physical principles as well as by their combinations. Different operating principles, structures, materials and fabrication methods are considered. A detailed analysis of the significant achievements in the technology of micro-optics, micro-magnets and micro-coil fabrication, along with the development of new magnetic materials during recent decades, which has driven the creation of new application domains for levitating micro-actuators is performed.

Fuzzy Constrained Predictive Optimal Control of High Speed Train with Actuator Dynamics

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Xi Wang

2016-01-01

Full Text Available We investigate the problem of fuzzy constrained predictive optimal control of high speed train considering the effect of actuator dynamics. The dynamics feature of the high speed train is modeled as a cascade of cars connected by flexible couplers, and the formulation is mathematically transformed into a Takagi-Sugeno (T-S fuzzy model. The goal of this study is to design a state feedback control law at each decision step to enhance safety, comfort, and energy efficiency of high speed train subject to safety constraints on the control input. Based on Lyapunov stability theory, the problem of optimizing an upper bound on the cruise control cost function subject to input constraints is reduced to a convex optimization problem involving linear matrix inequalities (LMIs. Furthermore, we analyze the influences of second-order actuator dynamics on the fuzzy constrained predictive controller, which shows risk of potentially deteriorating the overall system. Employing backstepping method, an actuator compensator is proposed to accommodate for the influence of the actuator dynamics. The experimental results show that with the proposed approach high speed train can track the desired speed, the relative coupler displacement between the neighbouring cars is stable at the equilibrium state, and the influence of actuator dynamics is reduced, which demonstrate the validity and effectiveness of the proposed approaches.

V-stack piezoelectric actuator

Science.gov (United States)

Ardelean, Emil V.; Clark, Robert L.

2001-07-01

Aeroelastic control of wings by means of a distributed, trailing-edge control surface is of interest with regards to maneuvers, gust alleviation, and flutter suppression. The use of high energy density, piezoelectric materials as motors provides an appealing solution to this problem. A comparative analysis of the state of the art actuators is currently being conducted. A new piezoelectric actuator design is presented. This actuator meets the requirements for trailing edge flap actuation in both stroke and force. It is compact, simple, sturdy, and leverages stroke geometrically with minimum force penalties while displaying linearity over a wide range of stroke. The V-Stack Piezoelectric Actuator, consists of a base, a lever, two piezoelectric stacks, and a pre-tensioning element. The work is performed alternately by the two stacks, placed on both sides of the lever. Pre-tensioning can be readily applied using a torque wrench, obviating the need for elastic elements and this is for the benefit of the stiffness of the actuator. The characteristics of the actuator are easily modified by changing the base or the stacks. A prototype was constructed and tested experimentally to validate the theoretical model.

Considerations for Contractile Electroactive Materials and Actuators

International Nuclear Information System (INIS)

Rasmussen, Lenore; Schramm, David; Meixler, Lewis D.; Gentile, Charles A.; Ascione, George; Tilson, Carl; Pagdon, Kelsey

2010-01-01

Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple, and now contract (new development) with low electric input. In addition, Ras Labs produces EAP materials that quickly contract and expand, repeatedly, by reversing the polarity of the electric input. These recent developments are important attributes in the field of electroactivity because of the ability of contraction and contraction-expansion to produce biomimetric motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to determine the mechanisms during contraction of these EAPs.

Displacement Models for THUNDER Actuators having General Loads and Boundary Conditions

Science.gov (United States)

Wieman, Robert; Smith, Ralph C.; Kackley, Tyson; Ounaies, Zoubeida; Bernd, Jeff; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

This paper summarizes techniques for quantifying the displacements generated in THUNDER actuators in response to applied voltages for a variety of boundary conditions and exogenous loads. The PDE (partial differential equations) models for the actuators are constructed in two steps. In the first, previously developed theory quantifying thermal and electrostatic strains is employed to model the actuator shapes which result from the manufacturing process and subsequent repoling. Newtonian principles are then employed to develop PDE models which quantify displacements in the actuator due to voltage inputs to the piezoceramic patch. For this analysis, drive levels are assumed to be moderate so that linear piezoelectric relations can be employed. Finite element methods for discretizing the models are developed and the performance of the discretized models are illustrated through comparison with experimental data.

Fabrication of a bubble-driven arrayed actuator for a tactile display

International Nuclear Information System (INIS)

Shikida, Mitsuhiro; Imamura, Tsubasa; Ukai, Shinji; Miyaji, Takaaki; Sato, Kazuo

2008-01-01

A chip-sized arrayed actuator device has been developed for application to a tactile display. Each actuator uses a liquid–vapour phase change to drive a microneedle that stimulates receptors in a finger in contact with the array. The actuators have a flexible diaphragm structure and a bottom plate bonded together to create a cavity between them. A microneedle and a microheater are formed on the diaphragm and plate of each actuator, respectively. The sealed cavity is filled with an operating liquid. Activating the heater and generating bubbles, which is similar to the process of a thermal ink jet, increase the pressure in the cavity. As a result, the flexible membrane deforms and it drives the needle upwards to stimulate receptors. Microelectromechanical systems technologies are used to fabricate the three components of the actuators, which are manually assembled to form a 3 × 3 arrayed actuator device. The total size of the device is 15 × 15 × 1 mm. The device performance is experimentally evaluated and a large needle displacement (61 µm) is obtained with an input energy of 457 mJ

LES-based characterization of a suction and oscillatory blowing fluidic actuator

Science.gov (United States)

Kim, Jeonglae; Moin, Parviz

2015-11-01

Recently, a novel fluidic actuator using steady suction and oscillatory blowing was developed for control of turbulent flows. The suction and oscillatory blowing (SaOB) actuator combines steady suction and pulsed oscillatory blowing into a single device. The actuation is based upon a self-sustained mechanism of confined jets and does not require any moving parts. The control output is determined by a pressure source and the geometric details, and no additional input is needed. While its basic mechanisms have been investigated to some extent, detailed characteristics of internal turbulent flows are not well understood. In this study, internal flows of the SaOB actuator are simulated using large-eddy simulation (LES). Flow characteristics within the actuator are described in detail for a better understanding of the physical mechanisms and improving the actuator design. LES predicts the self-sustained oscillations of the turbulent jet. Switching frequency, maximum velocity at the actuator outlets, and wall pressure distribution are in good agreement with the experimental measurements. The computational results are used to develop simplified boundary conditions for numerical experiments of active flow control. Supported by the Boeing company.

Neural network-based robust actuator fault diagnosis for a non-linear multi-tank system.

Science.gov (United States)

Mrugalski, Marcin; Luzar, Marcel; Pazera, Marcin; Witczak, Marcin; Aubrun, Christophe

2016-03-01

The paper is devoted to the problem of the robust actuator fault diagnosis of the dynamic non-linear systems. In the proposed method, it is assumed that the diagnosed system can be modelled by the recurrent neural network, which can be transformed into the linear parameter varying form. Such a system description allows developing the designing scheme of the robust unknown input observer within H∞ framework for a class of non-linear systems. The proposed approach is designed in such a way that a prescribed disturbance attenuation level is achieved with respect to the actuator fault estimation error, while guaranteeing the convergence of the observer. The application of the robust unknown input observer enables actuator fault estimation, which allows applying the developed approach to the fault tolerant control tasks. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Fabrication and characterization of a dual-joint smart inhaler nozzle actuated by embedded SMA wires

International Nuclear Information System (INIS)

Furst, Stephen J; Seelecke, Stefan

2014-01-01

Shape memory alloy (SMA) wires offer a novel solution for many embedded actuator and sensor applications. Small SMA wires in particular can be heated with a relatively low electric current, cool rapidly, and serve as a sensor thanks to a measurable resistance change. However, the challenges of fabrication with SMA actuator wires as well as their hysteretic nature have prevented them from finding mainstream application. This work focuses on the process used to control the fabrication of an SMA-actuated adaptive nozzle for the previously presented Smart Inhaler application. The elements of nozzle design that facilitate fabrication are summarized and an assembly setup and procedure is presented for controlling the stress and strain in the SMA wires while they are attached to the nozzle structure via temperature-resistant adhesives. Finally, the performance of the nozzle is characterized by measuring the changes in nozzle deflection and SMA wire strain and resistance in response to a controlled Joule heating power input. Results show controlling pre-stress in the wires during assembly can lead to reproducible behavior, an input heating power serves to control nozzle deflection, and a measured resistance can provide a useful sensor of SMA wire strain and nozzle joint deflection. (paper)

Toward the Design of Multi Asymmetric Surface Dielectric Barrier Discharge (ASDBD) Actuators

International Nuclear Information System (INIS)

Zadeh, Massiel; Rohani, V.; Cauneau, F.; Fabry, F.; Fulcheri, L.

2015-01-01

This paper investigates the electrical and mechanical behaviors of a single-ASDBD actuator and a two-ASDBD one supplied in sinusoidal mode (1–10 kHz). The main objective of our research is to determine the optimum frequency values for the function of these actuators with a given power supply. For this purpose, we determine the electrical power density input to the actuators versus frequency through two methods: i) a semi-theoretical method, based on an impedance calculation, and ii) an experimental method, based on direct electrical measurements. These methods show that the addition of a second ASDBD changes the resonance frequency value of the actuator by moving it towards low frequencies. After characterizing the aerodynamic mobile layer structure induced by the single-ASDBD actuator, we analyze experimentally the mechanical response of a two-ASDBD actuator as a function of the inter-ASDBD distance. The experiments demonstrate that the induced electric wind velocity and the electro-mechanical yield of a two-ASDBD actuator reach a maximum value for an optimum inter-ASDBD distance, which is a useful value for the design of highly efficient multi-ASDBD actuators. (plasma technology)

PROVIDING ENGLISH LANGUAGE INPUT: DECREASING STUDENTS’ ANXIETY IN READING COMPREHENSION PERFORMANCE

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Elva Yohana

2016-11-01

Full Text Available The primary condition for successful in second or foreign language learning is providing an adequate environment. It is as a medium of increasing the students’ language exposure in order to be able to success in acquiring second or foreign language profciency. This study was designed to propose the adequate English language input that can decrease the students’ anxiety in reading comprehension performance. Of the four skills, somehow reading can be regarded as especially important because reading is assumed to be the central means for learning new information. Some students, however, still encounter many problems in reading. It is because of their anxiety when they are reading. Providing and creating an interesting-contextual reading material and gratifed teachers can make out this problem which occurs mostly in Indonesian’s classrooms. It revealed that the younger learners of English there do not received adequate amount of the target language input in their learning of English. Hence, it suggested the adoption of extensive reading programs as the most effective means in the creation of an input-rich environment in EFL learning contexts. Besides they also give suggestion to book writers and publisher to provide myriad books that appropriate and readable for their students.

The Absolute Stability Analysis in Fuzzy Control Systems with Parametric Uncertainties and Reference Inputs

Science.gov (United States)

Wu, Bing-Fei; Ma, Li-Shan; Perng, Jau-Woei

This study analyzes the absolute stability in P and PD type fuzzy logic control systems with both certain and uncertain linear plants. Stability analysis includes the reference input, actuator gain and interval plant parameters. For certain linear plants, the stability (i.e. the stable equilibriums of error) in P and PD types is analyzed with the Popov or linearization methods under various reference inputs and actuator gains. The steady state errors of fuzzy control systems are also addressed in the parameter plane. The parametric robust Popov criterion for parametric absolute stability based on Lur'e systems is also applied to the stability analysis of P type fuzzy control systems with uncertain plants. The PD type fuzzy logic controller in our approach is a single-input fuzzy logic controller and is transformed into the P type for analysis. In our work, the absolute stability analysis of fuzzy control systems is given with respect to a non-zero reference input and an uncertain linear plant with the parametric robust Popov criterion unlike previous works. Moreover, a fuzzy current controlled RC circuit is designed with PSPICE models. Both numerical and PSPICE simulations are provided to verify the analytical results. Furthermore, the oscillation mechanism in fuzzy control systems is specified with various equilibrium points of view in the simulation example. Finally, the comparisons are also given to show the effectiveness of the analysis method.

Inducement of Design Parameters for Reliability Improvement of Servo Actuator for Hydraulic Valve Operation

Energy Technology Data Exchange (ETDEWEB)

Sung, Baek Ju; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

2014-05-15

The precision hydraulic valve is widely used in various industrial field like aircraft, automobile, and general machinery. Servo actuator is the most important device for driving the precise hydraulic valve. The reliable operation of servo actuator effects on the overall hydraulic system. The performance of servo actuator relies on frequency response and step response according to arbitrary input signal. In this paper, we performed the analysis for the components of servo actuator to satisfy the reliable operation and response characteristics through the reliability analysis, and also induced the design parameters to realize the reliable operation and fast response characteristics of servo actuator for hydraulic valve operation through the empirical knowledge of experts and electromagnetic theories. We suggested the design equations to determine the values of design parameters of servo actuator as like bobbin size, length of yoke and plunger and turn number of coil, and verified the achieved design values through FEM analysis and performance tests using some prototypes of servo actuators adapted in hydraulic valve.

Piezoelectric-based actuators for improved tractor-trailer performance (Conference Presentation)

Science.gov (United States)

Menicovich, David; Amitay, Michael; Gallardo, Daniele

2017-04-01

The application of piezo-electrically-driven synthetic-jet-based active flow control to reduce drag on tractor-trailers and to improve thermal mixing in refrigerated trailers was explored on full-scale tests. The active flow control technique that is being used relies on a modular system comprised of distributed, small, highly efficient actuators. These actuators, called synthetic jets, are jets that are synthesized at the edge of an orifice by a periodic motion of a piezoelectric diaphragm(s) mounted on one (or more) walls of a sealed cavity. The synthetic jet is zero net mass flux (ZNMF), but it allows momentum transfer to flow. It is typically driven near diaphragm and/or cavity resonance, and therefore, small electric input [O(10W)] is required. Another advantage of this actuator is that no plumbing is required. The system doesn't require changes to the body of the truck, can be easily reconfigured to various types of vehicles, and consumes small amounts of electrical power from the existing electrical system of the truck. The actuators are operated in a closed feedback loop based on inputs received from the tractor's electronic control unit, various system components and environmental sensors. The data are collected and processed on-board and transmitted to a cloud-based data management platform for further big data analytics and diagnostics. The system functions as a smart connected product through the interchange of data between the physical truck-mounted system and its cloud platform.

Validation and modification of the Blade Element Momentum theory based on comparisons with actuator disc simulations

DEFF Research Database (Denmark)

Aagaard Madsen, Helge; Bak, Christian; Døssing, Mads

2010-01-01

A comprehensive investigation of the Blade Element Momentum (BEM) model using detailed numerical simulations with an axis symmetric actuator disc (AD) model has been carried out. The present implementation of the BEM model is in a version where exactly the same input in the form of non-dimensiona......A comprehensive investigation of the Blade Element Momentum (BEM) model using detailed numerical simulations with an axis symmetric actuator disc (AD) model has been carried out. The present implementation of the BEM model is in a version where exactly the same input in the form of non...

Method for driving an actuator, actuator drive, and apparatus comprising an actuator

NARCIS (Netherlands)

2010-01-01

An actuator driver circuit includes a drive signal source and an electrical damping element having a negative resistance connected in series with the drive signal source. A controllable switch is provided for selectively switching the electrical damping element into or put of a signal path from a

Numerical investigation of aerodynamic flow actuation produced by surface plasma actuator on 2D oscillating airfoil

Directory of Open Access Journals (Sweden)

Minh Khang Phan

2016-08-01

Full Text Available Numerical simulation of unsteady flow control over an oscillating NACA0012 airfoil is investigated. Flow actuation of a turbulent flow over the airfoil is provided by low current DC surface glow discharge plasma actuator which is analytically modeled as an ion pressure force produced in the cathode sheath region. The modeled plasma actuator has an induced pressure force of about 2 kPa under a typical experiment condition and is placed on the airfoil surface at 0% chord length and/or at 10% chord length. The plasma actuator at deep-stall angles (from 5° to 25° is able to slightly delay a dynamic stall and to weaken a pressure fluctuation in down-stroke motion. As a result, the wake region is reduced. The actuation effect varies with different plasma pulse frequencies, actuator locations and reduced frequencies. A lift coefficient can increase up to 70% by a selective operation of the plasma actuator with various plasma frequencies and locations as the angle of attack changes. Active flow control which is a key advantageous feature of the plasma actuator reveals that a dynamic stall phenomenon can be controlled by the surface plasma actuator with less power consumption if a careful control scheme of the plasma actuator is employed with the optimized plasma pulse frequency and actuator location corresponding to a dynamic change in reduced frequency.

Working principle of bio-inspired shape memory alloy composite actuators

International Nuclear Information System (INIS)

Smith, Colin; Villanueva, Alex; Joshi, Keyur; Tadesse, Yonas; Priya, Shashank

2011-01-01

Recently, bio-inspired shape memory alloy composite (BISMAC) actuators have been shown to mimic the deformation characteristics of natural jellyfish medusa. In this study, a constant cross-section BISMAC actuator was characterized in terms of bending deflection and force in conjunction with microscopy to understand its deformation mechanism. The actuator showed bending deflection of 111% with respect to the active length along with a blocking force of 0.061 N. The resulting energy density of the composite actuator was 4929 J m −3 at an input voltage and current level of 12 V and 0.7 A, respectively. For a dry-state actuator, this performance is extremely high and represents an optimum combination of force and deflection. Experiments reveal that BISMAC's performance is related to the moment induced from tip attachment of the shape memory alloy (SMA) rather than to friction within the composite structure. A physics-based model of BISMAC structure is presented which shows that the actuator is highly sensitive to the distance between the SMA wire and the incompressible component. While SMA has both stress and strain limitations, the limiting factor in BISMAC actuators is dependent on separation distance. The limiting factor in BISMAC's suitability for mimicking the performance of medusa was experimentally found to be related to the maximum 4% strain of the SMA and not its force generation. (fast track communication)

Experimental parametric study of a biomimetic fish robot actuated by piezoelectric actuators

Science.gov (United States)

Wiguna, T.; Park, Hoon C.; Heo, S.; Goo, Nam S.

2007-04-01

This paper presents an experiment and parametric study of a biomimetic fish robot actuated by the Lightweight Piezocomposite Actuator (LIPCA). The biomimetic aspects in this work are the oscillating tail beat motion and shape of caudal fin. Caudal fins that resemble fins of BCF (Body and Caudal Fin) mode fish were made in order to perform parametric study concerning the effect of caudal fin characteristics on thrust production at an operating frequency range. The observed caudal fin characteristics are the shape, stiffness, area, and aspect ratio. It is found that a high aspect ratio caudal fin contributes to high swimming speed. The robotic fish propelled by artificial caudal fins shaped after thunniform-fish and mackerel caudal fins, which have relatively high aspect ratio, produced swimming speed as high as 2.364 cm/s and 2.519 cm/s, respectively, for a 300 V p-p input voltage excited at 0.9 Hz. Thrust performance of the biomimetic fish robot is examined by calculating Strouhal number, Froude number, Reynolds number, and power consumption.

Probabilistic Analysis of Space Shuttle Body Flap Actuator Ball Bearings

Science.gov (United States)

Oswald, Fred B.; Jett, Timothy R.; Predmore, Roamer E.; Zaretsky, Erwin V.

2008-01-01

A probabilistic analysis, using the 2-parameter Weibull-Johnson method, was performed on experimental life test data from space shuttle actuator bearings. Experiments were performed on a test rig under simulated conditions to determine the life and failure mechanism of the grease lubricated bearings that support the input shaft of the space shuttle body flap actuators. The failure mechanism was wear that can cause loss of bearing preload. These tests established life and reliability data for both shuttle flight and ground operation. Test data were used to estimate the failure rate and reliability as a function of the number of shuttle missions flown. The Weibull analysis of the test data for the four actuators on one shuttle, each with a 2-bearing shaft assembly, established a reliability level of 96.9 percent for a life of 12 missions. A probabilistic system analysis for four shuttles, each of which has four actuators, predicts a single bearing failure in one actuator of one shuttle after 22 missions (a total of 88 missions for a 4-shuttle fleet). This prediction is comparable with actual shuttle flight history in which a single actuator bearing was found to have failed by wear at 20 missions.

A modeling framework for deteriorating control system and predictive maintenance of actuators

International Nuclear Information System (INIS)

Langeron, Y.; Grall, A.; Barros, A.

2015-01-01

Actuators play a central role in industrial automation systems. They are costly, and therefore studying their dependability needs all attention. Usually, an actuator is inserted in a feedback control system, and its mission is to implement a control action delivered by a controller. In this paper, a monotonic actuator deterioration is considered and it is assumed that a relationship exists between the control action and the physical actuator's deterioration. A modeling framework is proposed including a non-decreasing stochastic degradation process driving the inability for an actuator to fully implement its role. The prognosis of the actuator's residual useful lifetime is derived and used to update the controller's setting. The controller reconfiguration completes the maintenance corrective and preventive actions. This new action is suggested as an alternative for maintenance strategy. - Highlights: • A degrading control system model is proposed focusing on actuator deterioration. • It is assumed a relationship between this degradation and its loss of efficiency. • The actuator RUL is quantified as a quantile of its conditional survival function. • RUL prognosis is used to reconfigure the control input law. • This new action is suggested as an alternative for maintenance strategy

A Completely New Type of Actuator -or- This Ain't Your Grandfather's Internal Combustion Engine

Science.gov (United States)

Gore, Brian W.; Hawkins, Gary F.; Hess, Peter A.; Moore, Teresa A.; Fournier, Eric W.

2010-01-01

A completely new type of actuator - one that is proposed for use in a variety of environments from sea to land to air to space - has been designed, patented, built, and tested. The actuator is loosely based on the principle of the internal combustion engine, except that it is a completely closed system, only requiring electrical input, and the working fuel is water. This paper outlines the theory behind the electrolysis- and ignition-based cycle upon which the actuator operates and describes the performance capability test apparatus and results for the actuator. A mechanism application that harnessed the unit s power to twist a scaled rotor blade is also highlighted.

Development of a dry actuation conducting polymer actuator for micro-optical zoom lenses

Science.gov (United States)

Kim, Baek-Chul; Kim, Hyunseok; Nguyen, H. C.; Cho, M. S.; Lee, Y.; Nam, Jae-Do; Choi, Hyouk Ryeol; Koo, J. C.; Jeong, H.-S.

2008-03-01

The objective of the present work is to demonstrate the efficiency and feasibility of NBR (Nitrile Butadiene Rubber) based conducting polymer actuator that is fabricated into a micro zoon lens driver. Unlike the traditional conducting polymer that normally operates in a liquid, the proposed actuator successfully provides fairly effective driving performance for the zoom lens system in a dry environment. And this paper is including the experiment results for an efficiency improvement. The result suggested by an experiment was efficient in micro optical zoom lens system. In addition, the developed design method of actuator was given consideration to design the system.

Further results on open-loop compensation of rate-dependent hysteresis in a magnetostrictive actuator with the Prandtl-Ishlinskii model

Science.gov (United States)

Al Janaideh, Mohammad; Aljanaideh, Omar

2018-05-01

Apart from the output-input hysteresis loops, the magnetostrictive actuators also exhibit asymmetry and saturation, particularly under moderate to large magnitude inputs and at relatively higher frequencies. Such nonlinear input-output characteristics could be effectively characterized by a rate-dependent Prandtl-Ishlinskii model in conjunction with a function of deadband operators. In this study, an inverse model is formulated to seek real-time compensation of rate-dependent and asymmetric hysteresis nonlinearities of a Terfenol-D magnetostrictive actuator. The inverse model is formulated with the inverse of the rate-dependent Prandtl-Ishlinskii model, satisfying the threshold dilation condition, with the inverse of the deadband function. The inverse model was subsequently applied to the hysteresis model as a feedforward compensator. The proposed compensator is applied as a feedforward compensator to the actuator hardware to study its potential for rate-dependent and asymmetric hysteresis loops. The experimental results are obtained under harmonic and complex harmonic inputs further revealed that the inverse compensator can substantially suppress the hysteresis and output asymmetry nonlinearities in the entire frequency range considered in the study.

Development of localized arc filament RF plasma actuators for high-speed and high Reynolds number flow control

International Nuclear Information System (INIS)

Kim, J.-H.; Nishihara, M.; Adamovich, I.V.; Samimy, M.; Gorbatov, S.V.; Pliavaka, F.V.

2010-01-01

Recently developed localized arc filament plasma actuators (LAFPAs) have shown tremendous control authority in high-speed and high Reynolds number flow for mixing enhancement and noise mitigation. Previously, these actuators were powered by a high-voltage pulsed DC plasma generator with low energy coupling efficiency of 5-10%. In the present work, a new custom-designed 8-channel pulsed radio frequency (RF) plasma generator has been developed to power up to 8 plasma actuators operated over a wide range of forcing frequencies (up to 50 kHz) and duty cycles (1-50%), and at high energy coupling efficiency (up to 80-85%). This reduces input electrical power requirements by approximately an order of magnitude, down to 12 W per actuator operating at 10% duty cycle. The new pulsed RF plasma generator is scalable to a system with a large number of channels. Performance of pulsed RF plasma actuators used for flow control was studied in a Mach 0.9 circular jet with a Reynolds number of about 623,000 and compared with that of pulsed DC actuators. Eight actuators were distributed uniformly on the perimeter of a 2.54-cm diameter circular nozzle extension. Both types of actuators coupled approximately the same amount of power to the flow, but with drastically different electrical inputs to the power supplies. Particle image velocimetry measurements showed that jet centerline Mach number decay produced by DC and RF actuators operating at the same forcing frequencies and duty cycles is very similar. At a forcing Strouhal number near 0.3, close to the jet column instability frequency, well-organized periodic structures, with similar patterns and dimensions, were generated in the jets forced by both DC and RF actuators. Far-field acoustic measurements demonstrated similar trends in the overall sound pressure level (OASPL) change produced by both types of actuators, resulting in OASPL reduction up to 1.2-1.5 dB in both cases. We conclude that pulsed RF actuators demonstrate flow

Hydraulic actuator mechanism to control aircraft spoiler movements through dual input commands

Science.gov (United States)

Irick, S. C. (Inventor)

1981-01-01

An aircraft flight spoiler control mechanism is described. The invention enables the conventional, primary spoiler control system to retain its operational characteristics while accommodating a secondary input controlled by a conventional computer system to supplement the settings made by the primary input. This is achieved by interposing springs between the primary input and the spoiler control unit. The springs are selected to have a stiffness intermediate to the greater force applied by the primary control linkage and the lesser resistance offered by the spoiler control unit. Thus, operation of the primary input causes the control unit to yield before the springs, yet, operation of the secondary input, acting directly on the control unit, causes the springs to yield and absorb adjustments before they are transmitted into the primary control system.

Electromechanical actuation of buckypaper actuator: Material properties and performance relationships

International Nuclear Information System (INIS)

Cottinet, P.-J.; Souders, C.; Tsai, S.-Y.; Liang, R.; Wang, B.; Zhang, C.

2012-01-01

Carbon nanotubes can be assembled into macroscopic thin film materials called buckypapers. To incorporate buckypaper actuators into engineering systems, it is of high importance to understand their material property-actuation performance relationships in order to model and predict the behavior of these actuators. The electromechanical actuation of macroscopic buckypaper structures and their actuators, including single and multi-walled carbon nanotube buckypapers and aligned single-walled nanotube buckypapers, were analyzed and compared. From the experimental evidence, this Letter discusses the effects of the fundamental material properties, including Young modulus and electrical double layer properties, on actuation performance of the resultant actuators. -- Highlights: ► In this study we identified the figure of merit of the electromechanical conversion. ► Different type of buckypaper was realized and characterized for actuation properties. ► The results demonstrated the potential of Buckypapers/Nafion for actuation

Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

International Nuclear Information System (INIS)

Nguyen, Phuong-Bac; Choi, Seung-Bok

2013-01-01

This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out. (paper)

Accurate torque control of a bi-directional magneto-rheological actuator considering hysteresis and friction effects

Science.gov (United States)

Nguyen, Phuong-Bac; Choi, Seung-Bok

2013-05-01

This paper presents a novel type of magneto-rheological (MR) actuator called a bi-directional magneto-rheological (BMR) actuator and accurate torque control results considering both hysteresis and friction compensation. The induced torque of this actuator varies from negative to positive values. As a result, it can work as either a brake or a clutch depending on the scheme of current input. In our work, the configuration of the actuator as well as its driving system is presented first. Subsequently, a congruency hysteresis based (CBH) model to take account of the effect of the hysteresis is proposed. After that, a compensator based on this model is developed. In addition, the effect of dry friction, which exists inherently with MR actuators in general, is also considered. In order to assess the effectiveness of the hysteresis compensator, several experiments on modeling and control of the actuator with different waveforms are carried out.

Temperature sensitive self-actuated scram mechanism

International Nuclear Information System (INIS)

Giuggio, N.; Noyes, R.C.; Zaman, S.U.

1982-01-01

This invention provides a mechanism for rapidly dropping a neutron absorbing poison material into the core of an LMFBR type reactor, and in particular a mechanism that is self-actuated when the reactor coolant temperature reaches a critical value. A safety duct located in the reactor core and extending above the core contains an inner column that provides a vertical coolant flow path through the duct. One or more fuel pins are located in the duct, with a temperature-responsive actuator near their upper ends. A poison bundle surrounds the inner column within the duct, held in position by a release mechanism connected to the actuator. The inferred core temperature is sensed by a fluid confined within the actuator, and the expansion of the fluid is translated into a linear force used to activate the release mechanism

Tension Stiffened and Tendon Actuated Manipulator

Science.gov (United States)

Doggett, William R. (Inventor); Dorsey, John T. (Inventor); Ganoe, George G. (Inventor); King, Bruce D. (Inventor); Jones, Thomas C. (Inventor); Mercer, Charles D. (Inventor); Corbin, Cole K. (Inventor)

2015-01-01

A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge.

Optimum Operating Conditions for PZT Actuators for Vibrotactile Wearables

Science.gov (United States)

Logothetis, Irini; Matsouka, Dimitra; Vassiliadis, Savvas; Vossou, Clio; Siores, Elias

2018-04-01

Recently, vibrotactile wearables have received much attention in fields such as medicine, psychology, athletics and video gaming. The electrical components presently used to generate vibration are rigid; hence, the design and creation of ergonomical wearables are limited. Significant advances in piezoelectric components have led to the production of flexible actuators such as piezoceramic lead zirconate titanate (PZT) film. To verify the functionality of PZT actuators for use in vibrotactile wearables, the factors influencing the electromechanical conversion were analysed and tested. This was achieved through theoretical and experimental analyses of a monomorph clamped-free structure for the PZT actuator. The research performed for this article is a three-step process. First, a theoretical analysis presents the equations governing the actuator. In addition, the eigenfrequency of the film was analysed preceding the experimental section. For this stage, by applying an electric voltage and varying the stimulating electrical characteristics (i.e., voltage, electrical waveform and frequency), the optimum operating conditions for a PZT film were determined. The tip displacement was measured referring to the mechanical energy converted from electrical energy. From the results obtained, an equation for the mechanical behaviour of PZT films as actuators was deduced. It was observed that the square waveform generated larger tip displacements. In conjunction with large voltage inputs at the predetermined eigenfrequency, the optimum operating conditions for the actuator were achieved. To conclude, PZT films can be adapted to assist designers in creating comfortable vibrotactile wearables.

Quantification of dynamic property of pneumatic muscle actuator for design of therapeutic robot control.

Science.gov (United States)

Balasubramanian, Sivakumar; Huang, He; He, Jiping

2006-01-01

Robot-assisted therapy has shown potential in neuromotor rehabilitation. A therapeutic robot driven by pneumatic muscle actuators has been developed in our research group. However, the design of fine and real-time feedback robot control is a challenge. One of the difficulties is the lack of a general dynamic model of the pneumatic muscle actuator. In this study, a phenomenological model has been developed to quantify the dynamic behavior of pneumatic muscle actuator by fitting the experimental length response of the pneumatic muscle, to a step pressure input. In addition, comparison of the dynamic responses of two pneumatic muscles of different dimensions has also been studied. Several control strategies for the pneumatic muscle actuator are discussed based on the results from this study.

A novel hybrid actuation mechanism based XY nanopositioning stage with totally decoupled kinematics

Science.gov (United States)

Zhu, Wu-Le; Zhu, Zhiwei; Guo, Ping; Ju, Bing-Feng

2018-01-01

This paper reports the design, analysis and testing of a parallel two degree-of-freedom piezo-actuated compliant stage for XY nanopositioning by introducing an innovative hybrid actuation mechanism. It mainly features the combination of two Scott-Russell and a half-bridge mechanisms for double-stage displacement amplification as well as moving direction modulation. By adopting the leaf-type double parallelogram (LTDP) structures at both input and output ends of the hybrid mechanism, the lateral stiffness and dynamic characteristics are significantly improved while the parasitic motions are greatly eliminated. The XY nanopositioning stage is constructed with two orthogonally configured hybrid mechanisms along with the LTDP mechanisms for totally decoupled kinematics at both input and output ends. An analytical model was established to describe the complete elastic deformation behavior of the stage, with further verification through the finite element simulation. Finally, experiments were implemented to comprehensively evaluate both the static and dynamic performances of the proposed stage. Closed-loop control of the piezoelectric actuators (PEA) by integrating strain gauges was also conducted to effectively eliminate the nonlinear hysteresis of the stage.

FEM assisted design and simulation of novel electrothermal actuators

NARCIS (Netherlands)

Deladi, S.; Krijnen, Gijsbertus J.M.; Elwenspoek, Michael Curt

2003-01-01

In this work the authors present the design, simulation, and experimental results of novel electrothermal actuators, such as the trimorph actuator for out-of-plane motion, the coupled in-plane actuator for in-plane motion and an actuator providing combined in- and out-of-plane motion that have been

Actuator disc edge singularity. The key to a revised actuator disc concept and momentum theory

Energy Technology Data Exchange (ETDEWEB)

Kuik, G.A.M. van (The Wind Energy Group of the Technical University Eindhoven (NL))

1989-01-01

Since the beginning of rotor aerodynamics the actuator disc momentum theory occupies a prominant place in almost any textbook on this subject. Specially in axial flow the theory provides an easy and rather accurate performance prediction. The results first obtained by Lanchester for the induced power of a hovering rotor and the maximum power of a wind turbine are still used as guidelines for complicated calculations. On the other hand, experimental results for propellers are known to deviate systematically (some 10%) from the momentum theory results. This is commonly attributed to the differences between a real rotor and an actuator disc. However, some actuator disc- and actuator strip (the 2-dimensional version) experiments are described in literature, showing the same deviations from momentum theory results. Therefore, apart from the question how representative an actuator disc is for a real rotor, the actuator disc concept itself may be inadequate. This problem is the subject of the work describe here. It will be shown that the classical actuator disc concept ignores discrete forces resulting from a flow singularity at the edge of the disc. The (extended) momentum theory, applied to this actuator strip model, shows a shift of the results towards the experimental data, and for the static case (hover) even a quantitative agreement is obtained. (author) 12 refs.

Piezoelectric-hydraulic pump based band brake actuation system for automotive transmission control

Science.gov (United States)

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

2007-04-01

The actuation system of friction elements (such as band brakes) is essential for high quality operations in modern automotive automatic transmissions (in short, ATs). The current band brake actuation system consists of several hydraulic components, including the oil pump, the regulating valve and the control valves. In general, it has been recognized that the current AT band brake actuation system has many limitations. For example, the oil pump and valve body are relatively heavy and complex. Also, the oil pumps induce inherently large drag torque, which affects fuel economy. This research is to overcome these problems of the current system by exploring the utilization of a hybrid type piezo-hydraulic pump device for AT band brake control. This new actuating system integrates a piezo-hydraulic pump to the input of the band brake. Compared with the current systems, this new actuator features much simpler structure, smaller size, and lower weight. This paper describes the development, design and fabrication of the new stand-alone prototype actuator for AT band brake control. An analytical model is developed and validated using experimental data. Performance tests on the hardware and system simulations utilizing the validated model are performed to characterize the new prototype actuator. It is predicted that with increasing of accumulator pressure and driving frequency, the proposed prototype actuating system will satisfy the band brake requirement for AT shift control.

Actuator with Multi Degrees of Freedom(Actuator)

OpenAIRE

矢野, 智昭; Tomoaki, YANO; 産業技術総合研究所

2006-01-01

The advantages, problems and the recent developments of the actuator with multi degrees of freedom are presented. At first, the advantages of the actuator with multi degrees of freedom are described. Next, the problems needed to solve for practical use are presented. The recent applications of the actuator with multi degrees of freedom are also reviewed.

Force-Deformation Response of a SMA-Based Actuator Considering the Electric Current Intensity as Step-Input

Directory of Open Access Journals (Sweden)

Ion-Cornel Mituletu

2015-06-01

Full Text Available The goal of the paper is to accomplish the response regarding the force-displacement characteristic evolution, of a Shape Memory Alloy (SMA actuator element. This reveals the first research stage in controlling the SMA behavior, providing important information about the heating-cooling time intervals. Step excitation of the SMA is performed by few values of electric current intensity, which produces the heating of SMA element up to 90-95 oC. To meet the testing requirements, an adequate test stand has been set up, consisting of sensors for force, displacement and temperature. The analog values provided by sensors were acquired and afterwards analyzed. The values of temperature, displacement and force were achieved, and their characteristic evolution has been performed. Thus, the time intervals are resulted and some other important aspects have been observed, regarding the delay between parameters and the temperature overshoot

Compact, planar, translational piezoelectric bimorph actuator with Archimedes’ spiral actuating tethers

International Nuclear Information System (INIS)

Yang, Chenye; Liu, Sanwei; Livermore, Carol; Xie, Xin

2016-01-01

The design, analytical modelling, finite element analysis (FEA), and experimental characterization of a microelectromechanical system (MEMS) out-of-plane (vertical) translational piezoelectric lead–zirconate–titanate (PZT) bimorph actuator supported on Archimedes’ spiral tethers are presented. Three types of bimorph actuators with different electrode patterns (with spiral tethers half actuated, fully actuated with uniform polarity, or fully actuated with reversed polarity) are designed and modelled. The two actuators with the highest predicted performance (half actuated and fully actuated with uniform polarity) are implemented and characterized. Both designs are fabricated by commercial processes and are compatible with integration into more complex MEMS systems. Analytical modelling and FEA are used to analyze and predict the actuators’ displacements and blocking forces. Experimental measurements of the deflections and blocking forces of actuators with full uniform actuation and half actuation validate the design. At an applied voltage of 110 V, the out-of-plane deflections of the actuators with half actuation and full uniform actuation are measured at about 17 µ m and 29 µ m respectively, in good agreement with analytical predictions of 17.3 µ m and 34.2 µ m and FEA predictions of 17.1 µ m and 25.8 µ m. The blocking force for devices with half-actuated tethers is predicted to be 12 mN (analytical) and 10 mN (FEA), close to the experimental value of 9 mN. The blocking force for devices with full uniform actuation is predicted to be 23 mN (analytical) and 17 mN (FEA), as compared with 15 mN in experiments. (paper)

Design, testing and control of a magnetorheological actuator for assistive knee braces

International Nuclear Information System (INIS)

Chen, J Z; Liao, W H

2010-01-01

This paper is aimed at developing a smart actuator for assistive knee braces to provide assistance to disabled or elderly people with mobility problems. A magnetorheological (MR) actuator is developed to be used in assistive knee braces to provide controllable torque. The MR actuator can work as a brake or a clutch. When active torque is needed, the DC motor works and the MR actuator functions as a clutch to transfer the torque generated by the motor to the leg; when passive torque is desired, the DC motor is turned off and the MR actuator functions as a brake to provide controllable passive torque. The prototype of the developed MR actuator is fabricated and experiments are carried out to investigate the characteristics of the MR actuator. The results show that the MR actuator is able to provide sufficient torque needed for normal human activities. Adaptive control is proposed for controlling the MR actuator. Anti-windup strategy is used to achieve better control performance. Experiments on the MR actuator under control are also performed to study the torque tracking ability of the system

A rotary piezoelectric actuator using longitudinal and bending hybrid transducer

Directory of Open Access Journals (Sweden)

Yingxiang Liu

2012-12-01

Full Text Available A rotary piezoelectric actuator using bolt-clamped type transducer with double driving feet is proposed in this study. The first-order longitudinal and fourth-order bending vibration modes are superimposed in the actuator to produce elliptical movements on the driving tips. Longitudinal PZT and bending PZT are clamped between the exponential shape horns and the flange by bolts. The vibration shape changes of the actuator are presented to give a clear explanation of its working principle. Several structural parameters of the exponential shape horn are selected and adjusted to accomplish the tuning process of the longitudinal and bending resonance frequencies. The input impedance and vibration characteristics are calculated by using FEM method; the gained results verify the feasibility of the proposed actuator. After the fabrication of a prototype, its vibration characteristics are measured by using a scanning laser Doppler vibrometer; the tested results are in good agreement with the FEM calculated results. The mechanical output performance experiments state that the prototype achieves a maximum speed of 129 r/min and a maximum torque of 1.5 Nm.

Control Software for Piezo Stepping Actuators

Science.gov (United States)

Shields, Joel F.

2013-01-01

A control system has been developed for the Space Interferometer Mission (SIM) piezo stepping actuator. Piezo stepping actuators are novel because they offer extreme dynamic range (centimeter stroke with nanometer resolution) with power, thermal, mass, and volume advantages over existing motorized actuation technology. These advantages come with the added benefit of greatly reduced complexity in the support electronics. The piezo stepping actuator consists of three fully redundant sets of piezoelectric transducers (PZTs), two sets of brake PZTs, and one set of extension PZTs. These PZTs are used to grasp and move a runner attached to the optic to be moved. By proper cycling of the two brake and extension PZTs, both forward and backward moves of the runner can be achieved. Each brake can be configured for either a power-on or power-off state. For SIM, the brakes and gate of the mechanism are configured in such a manner that, at the end of the step, the actuator is in a parked or power-off state. The control software uses asynchronous sampling of an optical encoder to monitor the position of the runner. These samples are timed to coincide with the end of the previous move, which may consist of a variable number of steps. This sampling technique linearizes the device by avoiding input saturation of the actuator and makes latencies of the plant vanish. The software also estimates, in real time, the scale factor of the device and a disturbance caused by cycling of the brakes. These estimates are used to actively cancel the brake disturbance. The control system also includes feedback and feedforward elements that regulate the position of the runner to a given reference position. Convergence time for smalland medium-sized reference positions (less than 200 microns) to within 10 nanometers can be achieved in under 10 seconds. Convergence times for large moves (greater than 1 millimeter) are limited by the step rate.

Micro-patterning of resin-bonded NdFeB magnet for a fully integrated electromagnetic actuator

Science.gov (United States)

Tao, Kai; Wu, Jin; Kottapalli, Ajay Giri Prakash; Chen, Di; Yang, Zhuoqing; Ding, Guifu; Lye, Sun Woh; Miao, Jianmin

2017-12-01

This paper reports a fully-integrated, batch-fabricated electromagnetic actuator which features micro-patterned NdFeB magnets. The entire actuator is fabricated through MEMS-compatible laminated surface micromachining technology, eliminating the requirement for further component assembly processes. The fabrication strategy allowed the entire volume of the actuator to be reduced to a small size of 2.5 × 2.5 × 2 mm3, which is one of the smallest NdFeB-based electromagnetic actuators demonstrated to date. The magnetic properties of NdFeB thin films are further investigated and optimized using different types of lithographically-defined micromolds. By altering the direction of the input current, actuating displacements of approximately ±10 μm are achieved during both the attraction and the repulsion operations. This work demonstrates the viability and compatibility of using polymer-bonded magnets for magnetic MEMS applications.

Sleeve Muscle Actuator and Its Application in Transtibial Prostheses

Science.gov (United States)

Zheng, Hao; Shen, Xiangrong

2014-01-01

This paper describes the concept of a new sleeve muscle actuator, and a transtibial prosthesis design powered by this novel actuator. Inspired by the functioning mechanism of the traditional pneumatic muscle actuator, the sleeve muscle actuator incorporates a cylindrical insert to the center of the pneumatic muscle, which eliminates the central portion of the internal volume. As a result of this change, the sleeve muscle provides multiple advantages over the traditional pneumatic muscle, including the increased force capacity over the entire range of motion, reduced energy consumption, and faster dynamic response. Furthermore, utilizing the load-bearing tube as the insert, the sleeve muscle enables an innovative “actuation-load bearing” structure, which has a potential of generating a highly compact actuation system suitable for prosthetic use. Utilizing this new actuator, the preliminary design of a transtibial prosthesis is presented, which is able to provide sufficient torque output and range of motion for a 75 Kg amputee user in level walking. PMID:24187262

Overview of Actuated Arm Support Systems and Their Applications

Directory of Open Access Journals (Sweden)

E.A. Lomonova

2013-10-01

Full Text Available Arm support systems provide support throughout daily tasks, training or in an industrial environment. During the last decades a large diversity of actuated arm support systems have been developed. To analyze the actuation principles in these systems, an overview of actuated arm support systems is provided. This overview visualizes the current trends on research and development of these support systems and distinguishes three categories. These categories depend mainly on the functional status of the user environment, which defines the specifications. Therefore, the actuated arm support systems are classified according to their user environment, namely: ambulatory, rehabilitation and industrial. Furthermore, three main actuation principles and three mechanical construction principles have been identified.

Control-focused, nonlinear and time-varying modelling of dielectric elastomer actuators with frequency response analysis

International Nuclear Information System (INIS)

Jacobs, William R; Dodd, Tony J; Anderson, Sean R; Wilson, Emma D; Porrill, John; Assaf, Tareq; Rossiter, Jonathan

2015-01-01

Current models of dielectric elastomer actuators (DEAs) are mostly constrained to first principal descriptions that are not well suited to the application of control design due to their computational complexity. In this work we describe an integrated framework for the identification of control focused, data driven and time-varying DEA models that allow advanced analysis of nonlinear system dynamics in the frequency-domain. Experimentally generated input–output data (voltage-displacement) was used to identify control-focused, nonlinear and time-varying dynamic models of a set of film-type DEAs. The model description used was the nonlinear autoregressive with exogenous input structure. Frequency response analysis of the DEA dynamics was performed using generalized frequency response functions, providing insight and a comparison into the time-varying dynamics across a set of DEA actuators. The results demonstrated that models identified within the presented framework provide a compact and accurate description of the system dynamics. The frequency response analysis revealed variation in the time-varying dynamic behaviour of DEAs fabricated to the same specifications. These results suggest that the modelling and analysis framework presented here is a potentially useful tool for future work in guiding DEA actuator design and fabrication for application domains such as soft robotics. (paper)

The optimal location of piezoelectric actuators and sensors for vibration control of plates

Science.gov (United States)

Kumar, K. Ramesh; Narayanan, S.

2007-12-01

This paper considers the optimal placement of collocated piezoelectric actuator-sensor pairs on a thin plate using a model-based linear quadratic regulator (LQR) controller. LQR performance is taken as objective for finding the optimal location of sensor-actuator pairs. The problem is formulated using the finite element method (FEM) as multi-input-multi-output (MIMO) model control. The discrete optimal sensor and actuator location problem is formulated in the framework of a zero-one optimization problem. A genetic algorithm (GA) is used to solve the zero-one optimization problem. Different classical control strategies like direct proportional feedback, constant-gain negative velocity feedback and the LQR optimal control scheme are applied to study the control effectiveness.

Dielectric Actuation of Polymers

Science.gov (United States)

Niu, Xiaofan

Dielectric polymers are widely used in a plurality of applications, such as electrical insulation, dielectric capacitors, and electromechanical actuators. Dielectric polymers with large strain deformations under an electric field are named dielectric elastomers (DE), because of their relative low modulus, high elongation at break, and outstanding resilience. Dielectric elastomer actuators (DEA) are superior to traditional transducers as a muscle-like technology: large strains, high energy densities, high coupling efficiency, quiet operation, and light weight. One focus of this dissertation is on the design of DE materials with high performance and easy processing. UV radiation curing of reactive species is studied as a generic synthesis methodology to provide a platform for material scientists to customize their own DE materials. Oligomers/monomers, crosslinkers, and other additives are mixed and cured at appropriate ratios to control the stress-strain response, suppress electromechanical instability of the resulting polymers, and provide stable actuation strains larger than 100% and energy densities higher than 1 J/g. The processing is largely simplified in the new material system by removal of the prestretching step. Multilayer stack actuators with 11% linear strain are demonstrated in a procedure fully compatible with industrial production. A multifunctional DE derivative material, bistable electroactive polymer (BSEP), is invented enabling repeatable rigid-to-rigid deformation without bulky external structures. Bistable actuation allows the polymer actuator to have two distinct states that can support external load without device failure. Plasticizers are used to lower the glass transition temperature to 45 °C. Interpenetrating polymer network structure is established inside the BSEP to suppress electromechanical instability, providing a breakdown field of 194 MV/m and a stable bistable strain as large as 228% with a 97% strain fixity. The application of BSEP

The Lower Extremities Exoskeleton Actuator Dynamics Research Taking into Account Support Reaction

Directory of Open Access Journals (Sweden)

A. A. Vereikin

2014-01-01

Full Text Available The article shows high relevance of research, aimed at the robotic exoskeleton creation. It defines some problems related to the process of their designing; including a lack of power supply to provide enough autonomy, and difficulties of man-machine complex control. There is a review of literature on the walking robots with tree-like kinematic structure development. This work reflects the continuing investigations, currently conducted by the authors, and relies heavily on the results of previous works, devoted to this subject.The article presents the exoskeleton dynamics equation, taking into account the impact of external forces and torques, as well as external relations imposed. Using a model of lower extremities exoskeleton developed in SolidWorks software complex, baricentric parameters of the actuator links were found. The different types of movements, committed due to harmonic changes of generalized coordinates in exoskeleton degrees of mobility, equipped with electrohydraulic actuators, were analyzed. The laws of generalized coordinate changes in time, corresponding to the worst case loading, were found. All the necessary input data for the exoskeleton dynamics equation solution were determined.The numerical values of all components of the dynamics equation were obtained as result of the dynamics equation simulation. In this case, the exoskeleton actuator load capacity was assumed to be 50 kg. The article shows dependences of torque and power in the actuator degrees of mobility on the time, as well as a curve of total capacity of all drives both, ignoring and taking into consideration the support surface reactions. Obtained dependences are the initial data for the calculation of the drive system.The proposed method for determination of exoskeleton energy parameters allows developer to perform a prompt evaluation of various options for the actuator design in accordance with the selected criteria. As a main evaluation criterion, a minimum

Three-dimensional Locomotion and Drilling Microrobot Using Electromagnetic Actuation System

International Nuclear Information System (INIS)

Li, Girl; Choi, Hyun Chul; Cha, Kyoung Rae; Jeong, Se Mi; Park, Jong Oh; Park, Suk Ho

2011-01-01

In this study, a novel electromagnetic microrobot system with locomotion and drilling functions in three dimensional space was developed. Because of size limitations, the microrobot does not have actuator, battery, and controller. Therefore, an electromagnetic actuation (EMA) system was used to drive the robot. The proposed EMA system consists of three rectangular Helmholtz coil pairs in x-, y- and z-axes and a Maxwell coil pair in the z-axis. The magnetic field generated in the EMA coil system could be controlled by the input current of the EMA coil. Finally, through various experiments, the locomotion and drilling performances of the proposed EMA microrobot system were verified

Three-dimensional Locomotion and Drilling Microrobot Using Electromagnetic Actuation System

Energy Technology Data Exchange (ETDEWEB)

Li, Girl; Choi, Hyun Chul; Cha, Kyoung Rae; Jeong, Se Mi; Park, Jong Oh; Park, Suk Ho [Chonnam National University, Gwangju (Korea, Republic of)

2011-12-15

In this study, a novel electromagnetic microrobot system with locomotion and drilling functions in three dimensional space was developed. Because of size limitations, the microrobot does not have actuator, battery, and controller. Therefore, an electromagnetic actuation (EMA) system was used to drive the robot. The proposed EMA system consists of three rectangular Helmholtz coil pairs in x-, y- and z-axes and a Maxwell coil pair in the z-axis. The magnetic field generated in the EMA coil system could be controlled by the input current of the EMA coil. Finally, through various experiments, the locomotion and drilling performances of the proposed EMA microrobot system were verified.

An electromagnetically actuated fiber optic switch using magnetized ferromagnetic materials

Science.gov (United States)

Pandojirao-S, Praveen; Dhaubanjar, Naresh; Phuyal, Pratibha C.; Chiao, Mu; Chiao, J.-C.

2008-03-01

This paper presents the design, fabrication and testing of a fiber optic switch actuated electromagnetically. The ferromagnetic gel coated optical fiber is actuated using external electromagnetic fields. The ferromagnetic gel consists of ferromagnetic powders dispersed in epoxy. The fabrication utilizes a simple cost-effective coating setup. A direct fiberto-fiber alignment eliminates the need for complementary optical parts and the displacement of fiber switches the laser coupling. The magnetic characteristics of magnetized ferromagnetic materials are performed using alternating gradient magnetometer and the magnetic hysteresis curves are measured for different ferromagnetic materials including iron, cobalt, and nickel. Optical fiber switches with various fiber lengths are actuated and their static and dynamic responses for the same volume of ferromagnetic gel are summarized. The highest displacement is 1.345 mm with an input current of 260mA. In this paper, the performance of fiber switches with various coating materials is presented.

Actuator assembly including a single axis of rotation locking member

Science.gov (United States)

Quitmeyer, James N.; Benson, Dwayne M.; Geck, Kellan P.

2009-12-08

An actuator assembly including an actuator housing assembly and a single axis of rotation locking member fixedly attached to a portion of the actuator housing assembly and an external mounting structure. The single axis of rotation locking member restricting rotational movement of the actuator housing assembly about at least one axis. The single axis of rotation locking member is coupled at a first end to the actuator housing assembly about a Y axis and at a 90.degree. angle to an X and Z axis providing rotation of the actuator housing assembly about the Y axis. The single axis of rotation locking member is coupled at a second end to a mounting structure, and more particularly a mounting pin, about an X axis and at a 90.degree. angle to a Y and Z axis providing rotation of the actuator housing assembly about the X axis. The actuator assembly is thereby restricted from rotation about the Z axis.

Tunable smart digital structure (SDS) to modularly assemble soft actuators with layered adhesive bonding

Science.gov (United States)

Jin, Hu; Dong, Erbao; Xu, Min; Xia, Qirong; Liu, Shuai; Li, Weihua; Yang, Jie

2018-01-01

Many shape memory alloy (SMA)-based soft actuators have specific composite structures and manufacture processes, and are therefore unique. However, these exclusive characteristics limit their capabilities and applications, so in this article a soft and smart digital structure (SDS) is proposed that acts like a modular unit to assemble soft actuators by a layered adhesive bonding process. The SDS is a fully soft structure that encapsulates a digital skeleton consisting of four groups of parallel and independently actuated SMA wires capable of outputting a four-channel tunable force. The layered adhesive bonding process modularly bonds several SDSs with an elastic backbone to fabricate a layered soft actuator where the elastic backbone is used to recover the SDSs in a cooling process using the SMA wires. Two kinds of SDS-based soft actuators were modularly assembled, an actuator, SDS-I, with a two-dimensional reciprocal motion, and an actuator, SDS-II, capable of bi-directional reciprocal motion. The thermodynamics and phase transformation modeling of the SDS-based actuator were analyzed. Several extensional soft actuators were also assembled by bonding the SDS with an anomalous elastic backbone or modularly assembling the SDS-Is and SDS-IIs. These modularly assembled soft actuators delivered more output channels and a complicated motion, e.g., an actinomorphic soft actuator with four SDS-Is jumps in a series of hierarchical heights and directional movement by tuning the input channels of the SDSs. This result showed that the SDS can modularly assemble multifarious soft actuators with diverse capabilities, steerability and tunable outputs.

A new method for fluid input into a hybrid synthetic jet actuator

Directory of Open Access Journals (Sweden)

Kordík J.

2014-03-01

Full Text Available A new principle of flow rectification for hybrid synthetic jet actuators is introduced in this paper. As is well known, the flow rectification can be best accomplished by means of fluidic diodes. Novelty of the present study are fluidic diodes with two mutually opposed nozzles. Interaction between the periodic jet flows from the nozzles causes a difference between the blowing and suction strokes, resulting in a particularly efficient rectification effect. The distance between the nozzle exits as well as the oscillation frequency were the parameters, which were varied during hot-wire measurements. The combination of those parameters achieving the highest volumetric effciency was identified.

Development of body weight support gait training system using pneumatic Mckibben actuators -control of lower extremity orthosis.

Science.gov (United States)

Mat Dzahir, M A; Nobutomo, T; Yamamoto, S I

2013-01-01

Recently, robot assisted therapy devices are increasingly used for spinal cord injury (SCI) rehabilitation in assisting handicapped patients to regain their impaired movements. Assistive robotic systems may not be able to cure or fully compensate impairments, but it should be able to assist certain impaired functions and ease movements. In this study, the control system of lower extremity orthosis for the body weight support gait training system which implements pneumatic artificial muscle (PAM) is proposed. The hip and knee joint angles of the gait orthosis system are controlled based on the PAM coordinates information from the simulation. This information provides the contraction data for the mono- and bi-articular PAMs that are arranged as posterior and anterior actuators to simulate the human walking motion. The proposed control system estimates the actuators' contraction as a function of hip and knee joint angles. Based on the contraction model obtained, input pressures for each actuators are measured. The control system are performed at different gait cycles and two PMA settings for the mono- and bi-articular actuators are evaluated in this research. The results showed that the system was able to achieve the maximum muscle moment at the joints, and able to perform the heel contact movement. This explained that the antagonistic mono- and bi-articular actuators worked effectively.

Hydrodynamic analysis, performance assessment, and actuator design of a flexible tail propulsor in an artificial alligator

International Nuclear Information System (INIS)

Philen, Michael; Neu, Wayne

2011-01-01

The overall objective of this research is to develop analysis tools for determining actuator requirements and assessing viable actuator technology for design of a flexible tail propulsor in an artificial alligator. A simple hydrodynamic model that includes both reactive and resistive forces along the tail is proposed and the calculated mean thrust agrees well with conventional estimates of drag. Using the hydrodynamic model forces as an input, studies are performed for an alligator ranging in size from 1 cm to 2 m at swimming speeds of 0.3–1.8 body lengths per second containing five antagonistic pairs of actuators distributed along the length of the tail. Several smart materials are considered for the actuation system, and preliminary analysis results indicate that the acrylic electroactive polymer and the flexible matrix composite actuators are potential artificial muscle technologies for the system

Design of a power-asymmetric actuator for a transtibial prosthesis.

Science.gov (United States)

Bartlett, Harrison L; Lawson, Brian E; Goldfarb, Michael

2017-07-01

This paper presents the design and characterization of a power-asymmetric actuator for a transtibial prosthesis. The device is designed to provide the combination of: 1) joint locking, 2) high power dissipation, and 3) low power generation. This actuator functionality allows for a prosthesis to be designed with minimal mass and power consumption relative to a fully-powered robotic prosthesis while maintaining much of the functionality necessary for activities of daily living. The actuator achieves these design characteristics while maintaining a small form factor by leveraging a combination of electromechanical and hydraulic components. The design of the actuator is described herein, and results of an experimental characterization are provided that indicate that the actuator is capable of providing the functional capabilities required of an ankle prosthesis in a compact and lightweight package.

Flight control actuation system

Science.gov (United States)

Wingett, Paul T. (Inventor); Gaines, Louie T. (Inventor); Evans, Paul S. (Inventor); Kern, James I. (Inventor)

2006-01-01

A flight control actuation system comprises a controller, electromechanical actuator and a pneumatic actuator. During normal operation, only the electromechanical actuator is needed to operate a flight control surface. When the electromechanical actuator load level exceeds 40 amps positive, the controller activates the pneumatic actuator to offset electromechanical actuator loads to assist the manipulation of flight control surfaces. The assistance from the pneumatic load assist actuator enables the use of an electromechanical actuator that is smaller in size and mass, requires less power, needs less cooling processes, achieves high output forces and adapts to electrical current variations. The flight control actuation system is adapted for aircraft, spacecraft, missiles, and other flight vehicles, especially flight vehicles that are large in size and travel at high velocities.

Soft Robotic Actuators

Science.gov (United States)

Godfrey, Juleon Taylor

In this thesis a survey on soft robotic actuators is conducted. The actuators are classified into three main categories: Pneumatic Artificial Muscles (PAM), Electronic Electroactive Polymers (Electric EAP), and Ionic Electroactive Polymers (Ionic EAP). Soft robots can have many degrees and are more compliant than hard robots. This makes them suitable for applications that are difficult for hard robots. For each actuator background history, build materials, how they operate, and modeling are presented. Multiple actuators in each class are reviewed highlighting both their use and their mathematical formulation. In addition to the survey the McKibben actuator was chosen for fabrication and in-depth experimental analysis. Four McKibben actuators were fabricated using mesh sleeve, barbed hose fittings, and different elastic bladders. All were actuated using compressed air. Tensile tests were performed for each actuator to measure the tension force as air pressure increased from 20 to 100 psi in 10 psi increments. To account for material relaxation properties eleven trials for each actuator were run for 2-3 days. In conclusion, the smallest outer diameter elastic bladder was capable of producing the highest force due to the larger gap between the bladder and the sleeve.

High Voltage Bidirectional Flyback Converter Driving DEAP Actuator for Automotive Applications

DEFF Research Database (Denmark)

Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

2013-01-01

DEAP (Dielectric Electro Active Polymer) is a new type of smart material. The actuator based on DEAP material tends to be applied in a variety of occasions. It will have prosperous future when employed in automotive field. This paper is focused on the design and implementation of a low input...

Enhanced Design of a Soft Thin-Film Vibrotactile Actuator Based on PVC Gel

Directory of Open Access Journals (Sweden)

Won-Hyeong Park

2017-09-01

Full Text Available We fabricated a soft thin-film vibrotactile actuator, which can be easily inserted into wearable devices, based on an electroactive PVC gel. One of the most important factors in fabricating a soft and thin vibrotactile actuator is to create vibrational force strong enough to stimulate human skin in a wide frequency range. To achieve this, we investigate the working principle of the PVC gel and suggest a new structure in which most of electric energy contributes to the deformation of the PVC gel. Due to this structure, the vibrational amplitude of the proposed PVC gel actuator could considerably increase (0.816 g (g = 9.8 m/s2 at resonant frequency. The vibrotactile amplitude is proportional to the amount of input voltage. It increased from 0.05 g up to 0.416 g with increasing applied voltages from 200 V to 1 kV at 1 Hz. The experimental results show that the proposed actuator can create a variety of haptic sensations.

Shape memory system with integrated actuation using embedded particles

Science.gov (United States)

Buckley, Patrick R [New York, NY; Maitland, Duncan J [Pleasant Hill, CA

2009-09-22

A shape memory material with integrated actuation using embedded particles. One embodiment provides a shape memory material apparatus comprising a shape memory material body and magnetic pieces in the shape memory material body. Another embodiment provides a method of actuating a device to perform an activity on a subject comprising the steps of positioning a shape memory material body in a desired position with regard to the subject, the shape memory material body capable of being formed in a specific primary shape, reformed into a secondary stable shape, and controllably actuated to recover the specific primary shape; including pieces in the shape memory material body; and actuating the shape memory material body using the pieces causing the shape memory material body to be controllably actuated to recover the specific primary shape and perform the activity on the subject.

Double-Acting Sleeve Muscle Actuator for Bio-Robotic Systems

Directory of Open Access Journals (Sweden)

Hao Zheng

2013-11-01

Full Text Available This paper presents a new type of muscle-like actuator, namely double-acting (DA sleeve muscle actuator, which is suitable for the actuation of biologically-inspired and biomedical robotic systems, especially those serving human-assistance purposes (prostheses, orthoses, etc.. Developed based on the traditional pneumatic muscle actuator, the new DA sleeve muscle incorporates a unique insert at the center. With the insert occupying the central portion of the internal volume, this new actuator enjoys multiple advantages relative to the traditional pneumatic muscle, including a consistent increase of force capacity over the entire range of motion, and a significant decrease of energy consumption in operation. Furthermore, the insert encompasses an additional chamber, which generates an extension force when pressurized. As such, this new actuator provides a unique bi-directional actuation capability, and, thus, has a potential to significantly simplify the design of a muscle actuator-powered robotic system. To demonstrate this new actuator concept, a prototype has been designed and fabricated, and experiments conducted on this prototype demonstrated the enhanced force capacity and the unique bi-directional actuation capability.

Double-Acting Sleeve Muscle Actuator for Bio-Robotic Systems

Science.gov (United States)

Zheng, Hao; Shen, Xiangrong

2014-01-01

This paper presents a new type of muscle-like actuator, namely double-acting (DA) sleeve muscle actuator, which is suitable for the actuation of biologically-inspired and biomedical robotic systems, especially those serving human-assistance purposes (prostheses, orthoses, etc.). Developed based on the traditional pneumatic muscle actuator, the new DA sleeve muscle incorporates a unique insert at the center. With the insert occupying the central portion of the internal volume, this new actuator enjoys multiple advantages relative to the traditional pneumatic muscle, including a consistent increase of force capacity over the entire range of motion, and a significant decrease of energy consumption in operation. Furthermore, the insert encompasses an additional chamber, which generates an extension force when pressurized. As such, this new actuator provides a unique bi-directional actuation capability, and, thus, has a potential to significantly simplify the design of a muscle actuator-powered robotic system. To demonstrate this new actuator concept, a prototype has been designed and fabricated, and experiments conducted on this prototype demonstrated the enhanced force capacity and the unique bi-directional actuation capability. PMID:25264492

Double-Acting Sleeve Muscle Actuator for Bio-Robotic Systems.

Science.gov (United States)

Zheng, Hao; Shen, Xiangrong

2013-11-25

This paper presents a new type of muscle-like actuator, namely double-acting (DA) sleeve muscle actuator, which is suitable for the actuation of biologically-inspired and biomedical robotic systems, especially those serving human-assistance purposes (prostheses, orthoses, etc .). Developed based on the traditional pneumatic muscle actuator, the new DA sleeve muscle incorporates a unique insert at the center. With the insert occupying the central portion of the internal volume, this new actuator enjoys multiple advantages relative to the traditional pneumatic muscle, including a consistent increase of force capacity over the entire range of motion, and a significant decrease of energy consumption in operation. Furthermore, the insert encompasses an additional chamber, which generates an extension force when pressurized. As such, this new actuator provides a unique bi-directional actuation capability, and, thus, has a potential to significantly simplify the design of a muscle actuator-powered robotic system. To demonstrate this new actuator concept, a prototype has been designed and fabricated, and experiments conducted on this prototype demonstrated the enhanced force capacity and the unique bi-directional actuation capability.

Considerations for Contractile Electroactive Materials and Actuators

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

2010-02-19

Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

Considerations for Electroactive Polymeric Materials and Actuators

International Nuclear Information System (INIS)

Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Carl; Bernasek, Stephen L.; Abelev, Esta

2010-01-01

Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

Recent Advances in the Control of Piezoelectric Actuators

Directory of Open Access Journals (Sweden)

Ziqiang Chi

2014-11-01

Full Text Available The micro/nano positioning field has made great progress towards enabling the advance of micro/nano technology. Micro/nano positioning stages actuated by piezoelectric actuators are the key devices in micro/nano manipulation. The control of piezoelectric actuators has emerged as a hot topic in recent years. Piezoelectric materials have inherent hysteresis and creep nonlinearity, which can reduce the accuracy of the manipulation, even causing the instability of the whole system. Remarkable efforts have been made to compensate for the nonlinearity of piezoelectric actuation through the mathematical modelling and control approaches. This paper provides a review of recent advances on the control of piezoelectric actuators. After a brief introduction of basic components of typical piezoelectric micro/nano positioning platforms, the working principle and modelling of piezoelectric actuators are outlined in this paper. This is followed with the major control method and recent progress is presented in detail. Finally, some open issues and future work on the control of piezoelectric actuators are extensively discussed.

MEMS fluidic actuator

Science.gov (United States)

Kholwadwala, Deepesh K [Albuquerque, NM; Johnston, Gabriel A [Trophy Club, TX; Rohrer, Brandon R [Albuquerque, NM; Galambos, Paul C [Albuquerque, NM; Okandan, Murat [Albuquerque, NM

2007-07-24

The present invention comprises a novel, lightweight, massively parallel device comprising microelectromechanical (MEMS) fluidic actuators, to reconfigure the profile, of a surface. Each microfluidic actuator comprises an independent bladder that can act as both a sensor and an actuator. A MEMS sensor, and a MEMS valve within each microfluidic actuator, operate cooperatively to monitor the fluid within each bladder, and regulate the flow of the fluid entering and exiting each bladder. When adjacently spaced in a array, microfluidic actuators can create arbitrary surface profiles in response to a change in the operating environment of the surface. In an embodiment of the invention, the profile of an airfoil is controlled by independent extension and contraction of a plurality of actuators, that operate to displace a compliant cover.

How citizen advisory boards provide input into major waste policy decisions

International Nuclear Information System (INIS)

Rogers, E.; Murakami, L.; Hanson, L.

1995-01-01

Volunteer citizen boards, such as Site Specific Advisory Boards, can be a very important key to success for the Department of Energy's (DOE's) Waste Management program. These boards can provide informed, independent recommendations reflecting the diversity of the community and its values. A successful volunteer process requires collaboration among regulators, DOE and other Boards; knowing how and when to interface with the broader public; understanding the diversity and representational issues of a citizens group; knowing the open-quotes ins and outsclose quotes of working with volunteers; education and training and most importantly, planning. Volunteers on a citizens board were created to tackle the big picture, policy decisions. The chair of the Rocky Flats Citizens Advisory Board will describe her Board's successes, including the challenges in reaching consensus agreements, as well as the need for integration with other boards and the sites' on-going public involvement programs to provide the input the department is seeking. Finally, one of the greatest challenges for the boards is interfacing with the greater public-at-large, seeing how the CAB has overcome this challenge and integrating broader public input into its decisions

How citizen advisory boards provide input into major waste policy decisions

Energy Technology Data Exchange (ETDEWEB)

Rogers, E.; Murakami, L.; Hanson, L. [Rocky Flats Citizen Advisory Board, Westminster, CO (United States)

1995-12-31

Volunteer citizen boards, such as Site Specific Advisory Boards, can be a very important key to success for the Department of Energy`s (DOE`s) Waste Management program. These boards can provide informed, independent recommendations reflecting the diversity of the community and its values. A successful volunteer process requires collaboration among regulators, DOE and other Boards; knowing how and when to interface with the broader public; understanding the diversity and representational issues of a citizens group; knowing the {open_quotes}ins and outs{close_quotes} of working with volunteers; education and training and most importantly, planning. Volunteers on a citizens board were created to tackle the big picture, policy decisions. The chair of the Rocky Flats Citizens Advisory Board will describe her Board`s successes, including the challenges in reaching consensus agreements, as well as the need for integration with other boards and the sites` on-going public involvement programs to provide the input the department is seeking. Finally, one of the greatest challenges for the boards is interfacing with the greater public-at-large, seeing how the CAB has overcome this challenge and integrating broader public input into its decisions.

A phase field approach for the fully coupled thermo-electro-mechanical dynamics of nanoscale ferroelectric actuators

Science.gov (United States)

Wang, Dan; Du, Haoyuan; Wang, Linxiang; Melnik, Roderick

2018-05-01

The fully coupled thermo-electro-mechanical properties of nanoscale ferroelectric actuators are investigated by a phase field model. Firstly, the thermal effect is incorporated into the commonly-used phase field model for ferroelectric materials in a thermodynamic consistent way and the governing equation for the temperature field is derived. Afterwards, the modified model is numerically implemented to study a selected prototype of the ferroelectric actuators, where strain associated with electric field-induced non-180° domain switching is employed. The temperature variation and energy flow in the actuation process are presented, which enhances our understanding of the working mechanism of the actuators. Furthermore, the influences of the input voltage frequency and the thermal boundary condition on the temperature variation are demonstrated and carefully discussed in the context of thermal management for real applications.

A novel rate-independent hysteresis model of a piezostack actuator using the congruency property

International Nuclear Information System (INIS)

Nguyen, Phuong-Bac; Choi, Seung-Bok

2011-01-01

This paper presents a novel hysteresis prediction model for a piezostack actuator. The model proposed in this work is a type of rate-independent hysteresis and is formulated using the inherent congruency property which exists in most piezoelectric materials. Specifically, the model is established by exploiting the fact that the high-order hysteretic curve segment is congruent with its first-order one that is limited by the same consecutive maximum and minimum values of input. Thus, in order to successfully implement this model two discretized first-order datasets of the ascending and descending curves need to be experimentally identified in advance. Using both the identified datasets and the congruency property, a systematic approach for predicting the hysteresis of the piezostack actuator is then obtained in two cases of input voltage: monotonic ascending and monotonic descending. The developed model is experimentally realized in order to demonstrate the effectiveness on the hysteresis prediction. In the experiment, three waveforms of input excitation schemes—a triangular waveform of decreasing amplitude, a triangular waveform of increasing amplitude and a multi-extremes triangular waveform—are applied to the proposed model. The hysteresis characteristics of the piezostack actuator predicted from the proposed model are compared with those obtained from the classical Preisach model. It is shown that the proposed model gives better accuracy, less computation time for the hysteresis prediction and more feasibility to realize than the classical Preisach model

Bi-directional series-parallel elastic actuator and overlap of the actuation layers.

Science.gov (United States)

Furnémont, Raphaël; Mathijssen, Glenn; Verstraten, Tom; Lefeber, Dirk; Vanderborght, Bram

2016-01-27

Several robotics applications require high torque-to-weight ratio and energy efficient actuators. Progress in that direction was made by introducing compliant elements into the actuation. A large variety of actuators were developed such as series elastic actuators (SEAs), variable stiffness actuators and parallel elastic actuators (PEAs). SEAs can reduce the peak power while PEAs can reduce the torque requirement on the motor. Nonetheless, these actuators still cannot meet performances close to humans. To combine both advantages, the series parallel elastic actuator (SPEA) was developed. The principle is inspired from biological muscles. Muscles are composed of motor units, placed in parallel, which are variably recruited as the required effort increases. This biological principle is exploited in the SPEA, where springs (layers), placed in parallel, can be recruited one by one. This recruitment is performed by an intermittent mechanism. This paper presents the development of a SPEA using the MACCEPA principle with a self-closing mechanism. This actuator can deliver a bi-directional output torque, variable stiffness and reduced friction. The load on the motor can also be reduced, leading to a lower power consumption. The variable recruitment of the parallel springs can also be tuned in order to further decrease the consumption of the actuator for a given task. First, an explanation of the concept and a brief description of the prior work done will be given. Next, the design and the model of one of the layers will be presented. The working principle of the full actuator will then be given. At the end of this paper, experiments showing the electric consumption of the actuator will display the advantage of the SPEA over an equivalent stiff actuator.

Actuators Using Piezoelectric Stacks and Displacement Enhancers

Science.gov (United States)

Bar-Cohen, Yoseph; Sherrit, Stewart; Bao, Xiaoqi; Badescu, Mircea; Lee, Hyeong Jae; Walkenmeyer, Phillip; Lih, Shyh-Shiuh

2015-01-01

Actuators are used to drive all active mechanisms including machines, robots, and manipulators to name a few. The actuators are responsible for moving, manipulating, displacing, pushing and executing any action that is needed by the mechanism. There are many types and principles of actuation that are responsible for these movements ranging from electromagnetic, electroactive, thermo-mechanic, piezoelectric, electrostrictive etc. Actuators are readily available from commercial producers but there is a great need for reducing their size, increasing their efficiency and reducing their weight. Studies at JPL’s Non Destructive Evaluation and Advanced Actuators (NDEAA) Laboratory have been focused on the use of piezoelectric stacks and novel designs taking advantage of piezoelectric’s potential to provide high torque/force density actuation and high electromechanical conversion efficiency. The actuators/motors that have been developed and reviewed in this paper are operated by various horn configurations as well as the use of pre-stress flexures that make them thermally stable and increases their coupling efficiency. The use of monolithic designs that pre-stress the piezoelectric stack eliminates the use of compression stress bolt. These designs enable the embedding of developed solid-state motors/actuators in any structure with the only macroscopically moving parts are the rotor or the linear translator. Finite element modeling and design tools were used to determine the requirements and operation parameters and the results were used to simulate, design and fabricate novel actuators/motors. The developed actuators and performance will be described and discussed in this paper.

Soft, Rotating Pneumatic Actuator.

Science.gov (United States)

Ainla, Alar; Verma, Mohit S; Yang, Dian; Whitesides, George M

2017-09-01

This article describes a soft pneumatic actuator that generates cyclical motion. The actuator consists of several (three, four, or five) chambers (arranged around the circumference of a circle surrounding a central rod) that can be actuated independently using negative pressure (or partial vacuum). Sequential actuation of the four-chamber device using reduced pressure moves the central rod cyclically in an approximately square path. We characterize the trajectory of the actuator and the force exerted by it, as we vary the material used for fabrication, the number of chambers, and the size of the actuator. We demonstrate two applications of this actuator: to deliver fluid while stirring (by replacing the central rod with a needle) and for locomotion that mimics a reptilian gait (by combining four actuators together).

Adaptive control of a quadrotor aerial vehicle with input constraints and uncertain parameters

Science.gov (United States)

Tran, Trong-Toan; Ge, Shuzhi Sam; He, Wei

2018-05-01

In this paper, we address the problem of adaptive bounded control for the trajectory tracking of a Quadrotor Aerial Vehicle (QAV) while the input saturations and uncertain parameters with the known bounds are simultaneously taken into account. First, to deal with the underactuated property of the QAV model, we decouple and construct the QAV model as a cascaded structure which consists of two fully actuated subsystems. Second, to handle the input constraints and uncertain parameters, we use a combination of the smooth saturation function and smooth projection operator in the control design. Third, to ensure the stability of the overall system of the QAV, we develop the technique for the cascaded system in the presence of both the input constraints and uncertain parameters. Finally, the region of stability of the closed-loop system is constructed explicitly, and our design ensures the asymptotic convergence of the tracking errors to the origin. The simulation results are provided to illustrate the effectiveness of the proposed method.

Actuator Placement Via Genetic Algorithm for Aircraft Morphing

Science.gov (United States)

Crossley, William A.; Cook, Andrea M.

2001-01-01

This research continued work that began under the support of NASA Grant NAG1-2119. The focus of this effort was to continue investigations of Genetic Algorithm (GA) approaches that could be used to solve an actuator placement problem by treating this as a discrete optimization problem. In these efforts, the actuators are assumed to be "smart" devices that change the aerodynamic shape of an aircraft wing to alter the flow past the wing, and, as a result, provide aerodynamic moments that could provide flight control. The earlier work investigated issued for the problem statement, developed the appropriate actuator modeling, recognized the importance of symmetry for this problem, modified the aerodynamic analysis routine for more efficient use with the genetic algorithm, and began a problem size study to measure the impact of increasing problem complexity. The research discussed in this final summary further investigated the problem statement to provide a "combined moment" problem statement to simultaneously address roll, pitch and yaw. Investigations of problem size using this new problem statement provided insight into performance of the GA as the number of possible actuator locations increased. Where previous investigations utilized a simple wing model to develop the GA approach for actuator placement, this research culminated with application of the GA approach to a high-altitude unmanned aerial vehicle concept to demonstrate that the approach is valid for an aircraft configuration.

Soft buckling actuators

Energy Technology Data Exchange (ETDEWEB)

Yang, Dian; Whitesides, George M.

2017-12-26

A soft actuator is described, including: a rotation center having a center of mass; a plurality of bucklable, elastic structural components each comprising a wall defining an axis along its longest dimension, the wall connected to the rotation center in a way that the axis is offset from the center of mass in a predetermined direction; and a plurality of cells each disposed between two adjacent bucklable, elastic structural components and configured for connection with a fluid inflation or deflation source; wherein upon the deflation of the cell, the bucklable, elastic structural components are configured to buckle in the predetermined direction. A soft actuating device including a plurality of the soft actuators and methods of actuation using the soft actuator or soft actuating device disclosed herein are also described.

MEMS Actuators for Improved Performance and Durability

Science.gov (United States)

Yearsley, James M.

Micro-ElectroMechanical Systems (MEMS) devices take advantage of force-scaling at length scales smaller than a millimeter to sense and interact with directly with phenomena and targets at the microscale. MEMS sensors found in everyday devices like cell-phones and cars include accelerometers, gyros, pressure sensors, and magnetic sensors. MEMS actuators generally serve more application specific roles including micro- and nano-tweezers used for single cell manipulation, optical switching and alignment components, and micro combustion engines for high energy density power generation. MEMS rotary motors are actuators that translate an electric drive signal into rotational motion and can serve as rate calibration inputs for gyros, stages for optical components, mixing devices for micro-fluidics, etc. Existing rotary micromotors suffer from friction and wear issues that affect lifetime and performance. Attempts to alleviate friction effects include surface treatment, magnetic and electrostatic levitation, pressurized gas bearings, and micro-ball bearings. The present work demonstrates a droplet based liquid bearing supporting a rotary micromotor that improves the operating characteristics of MEMS rotary motors. The liquid bearing provides wear-free, low-friction, passive alignment between the rotor and stator. Droplets are positioned relative to the rotor and stator through patterned superhydrophobic and hydrophilic surface coatings. The liquid bearing consists of a central droplet that acts as the motor shaft, providing axial alignment between rotor and stator, and satellite droplets, analogous to ball-bearings, that provide tip and tilt stable operation. The liquid bearing friction performance is characterized through measurement of the rotational drag coefficient and minimum starting torque due to stiction and geometric effects. Bearing operational performance is further characterized by modeling and measuring stiffness, environmental survivability, and high

Bucky gel actuator displacement: experiment and model

International Nuclear Information System (INIS)

Ghamsari, A K; Zegeye, E; Woldesenbet, E; Jin, Y

2013-01-01

Bucky gel actuator (BGA) is a dry electroactive nanocomposite which is driven with a few volts. BGA’s remarkable features make this tri-layered actuator a potential candidate for morphing applications. However, most of these applications would require a better understanding of the effective parameters that influence the BGA displacement. In this study, various sets of experiments were designed to investigate the effect of several parameters on the maximum lateral displacement of BGA. Two input parameters, voltage and frequency, and three material/design parameters, carbon nanotube type, thickness, and weight fraction of constituents were selected. A new thickness ratio term was also introduced to study the role of individual layers on BGA displacement. A model was established to predict BGA maximum displacement based on the effect of these parameters. This model showed good agreement with reported results from the literature. In addition, an important factor in the design of BGA-based devices, lifetime, was investigated. (paper)

A conclusive scalable model for the complete actuation response for IPMC transducers

International Nuclear Information System (INIS)

McDaid, A J; Aw, K C; Haemmerle, E; Xie, S Q

2010-01-01

This paper proposes a conclusive scalable model for the complete actuation response for ionic polymer metal composites (IPMC). This single model is proven to be able to accurately predict the free displacement/velocity and force actuation at varying displacements, with up to 3 V inputs. An accurate dynamic relationship between the force and displacement has been established which can be used to predict the complete actuation response of the IPMC transducer. The model is accurate at large displacements and can also predict the response when interacting with external mechanical systems and loads. This model equips engineers with a useful design tool which enables simple mechanical design, simulation and optimization when integrating IPMC actuators into an application. The response of the IPMC is modelled in three stages: (i) a nonlinear equivalent electrical circuit to predict the current drawn, (ii) an electromechanical coupling term and (iii) a segmented mechanical beam model which includes an electrically induced torque for the polymer. Model parameters are obtained using the dynamic time response and results are presented demonstrating the correspondence between the model and experimental results over a large operating range. This newly developed model is a large step forward, aiding in the progression of IPMCs towards wide acceptance as replacements to traditional actuators

Nonlinear dynamic modeling for smart material electro-hydraulic actuator development

Science.gov (United States)

Larson, John P.; Dapino, Marcelo J.

2013-03-01

Smart material electro-hydraulic actuators use hydraulic rectification by one-way check valves to amplify the motion of smart materials, such as magnetostrictives and piezoelectrics, in order to create compact, lightweight actuators. A piston pump driven by a smart material is combined with a hydraulic cylinder to form a self-contained, power-by-wire actuator that can be used in place of a conventional hydraulic system without the need for hydraulic lines and a centralized pump. The performance of an experimental actuator driven by a 12.7 mm diameter, 114 mm length Terfenol-D rod is evaluated over a range of applied input frequencies, loads, and currents. The peak performance achieved is 37 W, moving a 220 N load at a rate of 17 cm/s and producing a blocked pressure of 12.5 MPa. Additional tests are conducted to quantify the dynamic behavior of the one-way reed valves using a scanning laser vibrometer to identify the frequency response of the reeds and the effect of the valve seat and fluid mass loading. A lumped-parameter model is developed for the system that includes valve inertia and fluid response nonlinearities, and the model results are compared with the experimental data.

Proprioceptive Actuation Design for Dynamic Legged locomotion

Science.gov (United States)

Kim, Sangbae; Wensing, Patrick; Biomimetic Robotics Lab Team

Designing an actuator system for highly-dynamic legged locomotion exhibited by animals has been one of the grand challenges in robotics research. Conventional actuators designed for manufacturing applications have difficulty satisfying challenging requirements for high-speed locomotion, such as the need for high torque density and the ability to manage dynamic physical interactions. It is critical to introduce a new actuator design paradigm and provide guidelines for its incorporation in future mobile robots for research and industry. To this end, we suggest a paradigm called proprioceptive actuation, which enables highly- dynamic operation in legged machines. Proprioceptive actuation uses collocated force control at the joints to effectively control contact interactions at the feet under dynamic conditions. In the realm of legged machines, this paradigm provides a unique combination of high torque density, high-bandwidth force control, and the ability to mitigate impacts through backdrivability. Results show that the proposed design provides an impact mitigation factor that is comparable to other quadruped designs with series springs to handle impact. The paradigm is shown to enable the MIT Cheetah to manage the application of contact forces during dynamic bounding, with results given down to contact times of 85ms and peak forces over 450N. As a result, the MIT Cheetah achieves high-speed 3D running up to 13mph and jumping over an 18-inch high obstacle. The project is sponsored by DARPA M3 program.

Rotational actuator of motor based on carbon nanotubes

Science.gov (United States)

Zettl, Alexander K.; Fennimore, Adam M.; Yuzvinsky, Thomas D.

2008-11-18

A rotational actuator/motor based on rotation of a carbon nanotube is disclosed. The carbon nanotube is provided with a rotor plate attached to an outer wall, which moves relative to an inner wall of the nanotube. After deposit of a nanotube on a silicon chip substrate, the entire structure may be fabricated by lithography using selected techniques adapted from silicon manufacturing technology. The structures to be fabricated may comprise a multiwall carbon nanotube (MWNT), two in plane stators S1, S2 and a gate stator S3 buried beneath the substrate surface. The MWNT is suspended between two anchor pads and comprises a rotator attached to an outer wall and arranged to move in response to electromagnetic inputs. The substrate is etched away to allow the rotor to freely rotate. Rotation may be either in a reciprocal or fully rotatable manner.

Control of a perturbed under-actuated mechanical system

KAUST Repository

Zayane, Chadia

2015-11-05

In this work, the trajectory tracking problem for an under-actuated mechanical system in presence of unknown input disturbances is addressed. The studied inertia wheel inverted pendulum falls in the class of non minimum phase systems. The proposed high order sliding mode control architecture including a controller and differentiator allows to track accurately the predefined trajectory and to stabilize the internal dynamics. The robustness of the proposed approach is illustrated through different perturbation and output noise configurations.

Actuator concepts and mechatronics

Science.gov (United States)

Gilbert, Michael G.; Horner, Garnett C.

1998-06-01

Mechatronic design implies the consideration of integrated mechanical, electrical, and local control characteristics in electromechanical device design. In this paper, mechatronic development of actuation device concepts for active aircraft aerodynamic flow control are presented and discussed. The devices are intended to be embedded in aircraft aerodynamic surfaces to provide zero-net-momentum jets or additional flow-vorticity to control boundary layers and flow- separation. Two synthetic jet device prototypes and one vorticity-on-demand prototype currently in development are described in the paper. The aspects of actuation materials, design approaches to generating jets and vorticity, and the integration of miniaturized electronics are stressed.

Full-order optimal compensators for flow control: the multiple inputs case

Science.gov (United States)

Semeraro, Onofrio; Pralits, Jan O.

2018-03-01

Flow control has been the subject of numerous experimental and theoretical works. We analyze full-order, optimal controllers for large dynamical systems in the presence of multiple actuators and sensors. The full-order controllers do not require any preliminary model reduction or low-order approximation: this feature allows us to assess the optimal performance of an actuated flow without relying on any estimation process or further hypothesis on the disturbances. We start from the original technique proposed by Bewley et al. (Meccanica 51(12):2997-3014, 2016. https://doi.org/10.1007/s11012-016-0547-3), the adjoint of the direct-adjoint (ADA) algorithm. The algorithm is iterative and allows bypassing the solution of the algebraic Riccati equation associated with the optimal control problem, typically infeasible for large systems. In this numerical work, we extend the ADA iteration into a more general framework that includes the design of controllers with multiple, coupled inputs and robust controllers (H_{∞} methods). First, we demonstrate our results by showing the analytical equivalence between the full Riccati solutions and the ADA approximations in the multiple inputs case. In the second part of the article, we analyze the performance of the algorithm in terms of convergence of the solution, by comparing it with analogous techniques. We find an excellent scalability with the number of inputs (actuators), making the method a viable way for full-order control design in complex settings. Finally, the applicability of the algorithm to fluid mechanics problems is shown using the linearized Kuramoto-Sivashinsky equation and the Kármán vortex street past a two-dimensional cylinder.

Pneumatic artificial muscle actuators for compliant robotic manipulators

Science.gov (United States)

Robinson, Ryan Michael

adaptive neural network control. Results demonstrated the benefits of an accurate model in model-based control, and the advantages of adaptive neural network control when a model is unavailable or variations in payload are expected. Lastly, a variable recruitment strategy was applied to a group of parallel muscles actuating a common joint. Increased manipulator efficiency was observed when fewer PAMs were activated, justifying the use of variable recruitment strategies. Overall, this research demonstrates the benefits of pneumatic artificial muscles as actuators in robotics applications. It demonstrates that PAM-based manipulators can be well-modeled and can achieve high tracking accuracy over a wide range of payloads and inputs while maintaining natural compliance.

Hydraulically-actuated operating system for an electric circuit breaker

Science.gov (United States)

Barkan, Philip; Imam, Imdad

1978-01-01

This hydraulically-actuated operating system comprises a cylinder, a piston movable therein in an opening direction to open a circuit breaker, and an accumulator for supplying pressurized liquid to a piston-actuating space within the cylinder. A normally-closed valve between the accumulator and the actuating space is openable to allow pressurized liquid from the accumulator to flow through the valve into the actuating space to drive the piston in an opening direction. A vent is located hydraulically between the actuating space and the valve for affording communication between said actuating space and a low pressure region. Flow control means is provided for restricting leakage through said vent to a rate that prevents said leakage from substantially detracting from the development of pressure within said actuatng space during the period from initial opening of the valve to the time when said piston has moved through most of its opening stroke. Following such period and while the valve is still open, said flow control means allows effective leakage through said vent. The accumulator has a limited capacity that results in the pressure within said actuating space decaying promptly to a low value as a result of effective leakage through said vent after the piston has moved through a circuit-breaker opening stroke and while the valve is in its open state. Means is provided for resetting the valve to its closed state in response to said pressure decay in the actuating space.

Electrical servo actuator bracket. [fuel control valves on jet engines

Science.gov (United States)

Sawyer, R. V. (Inventor)

1981-01-01

An electrical servo actuator is mounted on a support arm which is allowed to pivot on a bolt through a fixed mounting bracket. The actuator is pivotally connected to the end of the support arm by a bolt which has an extension allowed to pass through a slot in the fixed mounting bracket. An actuator rod extends from the servo actuator to a crank arm which turns a control shaft. A short linear thrust of the rod pivots the crank arm through about 90 for full-on control with the rod contracted into the servo actuator, and full-off control when the rod is extended from the actuator. A spring moves the servo actuator and actuator rod toward the control crank arm once the actuator rod is fully extended in the full-off position. This assures the turning of the control shaft to a full-off position. A stop bolt and slot are provided to limit pivot motion. Once fully extended, the spring pivots the motion.

Electric-Pneumatic Actuator: A New Muscle for Locomotion

Directory of Open Access Journals (Sweden)

Maziar Ahmad Sharbafi

2017-10-01

Full Text Available A better understanding of how actuator design supports locomotor function may help develop novel and more functional powered assistive devices or robotic legged systems. Legged robots comprise passive parts (e.g., segments, joints and connections which are moved in a coordinated manner by actuators. In this study, we propose a novel concept of a hybrid electric-pneumatic actuator (EPA as an enhanced variable impedance actuator (VIA. EPA is consisted of a pneumatic artificial muscle (PAM and an electric motor (EM. In contrast to other VIAs, the pneumatic artificial muscle (PAM within the EPA provides not only adaptable compliance, but also an additional powerful actuator with muscle-like properties, which can be arranged in different combinations (e.g., in series or parallel to the EM. The novel hybrid actuator shares the advantages of both integrated actuator types combining precise control of EM with compliant energy storage of PAM, which are required for efficient and adjustable locomotion. Experimental and simulation results based on the new dynamic model of PAM support the hypothesis that combination of the two actuators can improve efficiency (energy and peak power and performance, while does not increase control complexity and weight, considerably. Finally, the experiments on EPA adapted bipedal robot (knee joint of the BioBiped3 robot show improved efficiency of the actuator at different frequencies.

Piezoelectric Actuator with Frequency Characteristics for a Middle-Ear Implant.

Science.gov (United States)

Shin, Dong Ho; Cho, Jin-Ho

2018-05-24

The design and implementation of a novel piezoelectric-based actuator for an implantable middle-ear hearing aid is described in this paper. The proposed actuator has excellent low-frequency output characteristics, and can generate high output in a specific frequency band by adjusting the mechanical resonance. The actuator consists of a piezoelectric element, a miniature bellows, a cantilever membrane, a metal ring support, a ceramic tip, and titanium housing. The optimal structure of the cantilever-membrane design, which determines the frequency characteristics of the piezoelectric actuator, was derived through finite element analysis. Based on the results, the piezoelectric actuator was implemented, and its performance was verified through a cadaveric experiment. It was confirmed that the proposed actuator provides better performance than currently used actuators, in terms of frequency characteristics.

Considerations for Contractile Electroactive Polymeric Materials and Actuators

Energy Technology Data Exchange (ETDEWEB)

Rasmussen, Lenore; Erickson, Carl J.; Meixler, Lewis D.; Ascione, George; Gentile, Charles A.; Tilson, Charles; Bernasek, Stephen L.; Abelev, Esta

2009-06-16

Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface.

Considerations for Contractile Electroactive Polymeric Materials and Actuators

International Nuclear Information System (INIS)

Rasmussen, L.; Erickson, Carl J.; Meixler, Lewis D.; Ascione, G.; Gentile, Charles A.; Tilson, C.; Bernasek, Stephen L.; Abelev, E.

2009-01-01

Ras Labs produces electroactive polymer (EAP) based materials and actuators that bend, swell, ripple and now contract (new development) with low electric input. This is an important attribute because of the ability of contraction to produce life-like motion. The mechanism of contraction is not well understood. Radionuclide-labeled experiments were conducted to follow the movement of electrolytes and water in these EAPs when activated. Extreme temperature experiments were performed on the contractile EAPs with very favorable results. One of the biggest challenges in developing these actuators, however, is the electrode-EAP interface because of the pronounced movement of the EAP. Plasma treatments of metallic electrodes were investigated in order to improve the attachment of the embedded electrodes to the EAP material. Surface analysis, adhesive testing, and mechanical testing were conducted to test metal surfaces and metal-polymer interfaces. The nitrogen plasma treatment of titanium produced a strong metal-polymer interface; however, oxygen plasma treatment of both stainless steel and titanium produced even stronger metal-polymer interfaces. Plasma treatment of the electrodes allows for the embedded electrodes and the EAP material of the actuator to work and move as a unit, with no detachment, by significantly improving the metal-polymer interface

PVDF core-free actuator for Braille displays: design, fabrication process, and testing

Science.gov (United States)

Levard, Thomas; Diglio, Paul J.; Lu, Sheng-Guo; Gorny, Lee J.; Rahn, Christopher D.; Zhang, Q. M.

2011-04-01

Refreshable Braille displays require many, small diameter actuators to move the pins. The electrostrictive P(VDF-TrFECFE) terpolymer can provide the high strain and actuation force under modest electric fields that are required of this application. In this paper, we develop core-free tubular actuators and integrate them into a 3 × 2 Braille cell. The films are solution cast, stretched to 6 μm thick, electroded, laminated into a bilayer, rolled into a 2 mm diameter tube, bonded, and provided with top and bottom contacts. Experimental testing of 17 actuators demonstrates significant strains (up to 4%). A novel Braille cell is designed and fabricated using six of these actuators.

Development of X-Y servo pneumatic-piezoelectric hybrid actuators for position control with high response, large stroke and nanometer accuracy.

Science.gov (United States)

Chiang, Mao-Hsiung

2010-01-01

This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm) and nanometer accuracy (20 nm). In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO) system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

Development of X-Y Servo Pneumatic-Piezoelectric Hybrid Actuators for Position Control with High Response, Large Stroke and Nanometer Accuracy

Directory of Open Access Journals (Sweden)

Mao-Hsiung Chiang

2010-03-01

Full Text Available This study aims to develop a X-Y dual-axial intelligent servo pneumatic-piezoelectric hybrid actuator for position control with high response, large stroke (250 mm, 200 mm and nanometer accuracy (20 nm. In each axis, the rodless pneumatic actuator serves to position in coarse stroke and the piezoelectric actuator compensates in fine stroke. Thus, the overall control systems of the single axis become a dual-input single-output (DISO system. Although the rodless pneumatic actuator has relatively larger friction force, it has the advantage of mechanism for multi-axial development. Thus, the X-Y dual-axial positioning system is developed based on the servo pneumatic-piezoelectric hybrid actuator. In addition, the decoupling self-organizing fuzzy sliding mode control is developed as the intelligent control strategies. Finally, the proposed novel intelligent X-Y dual-axial servo pneumatic-piezoelectric hybrid actuators are implemented and verified experimentally.

Fault Tolerance for Industrial Actuators in Absence of Accurate Models and Hardware Redundancy

DEFF Research Database (Denmark)

Papageorgiou, Dimitrios; Blanke, Mogens; Niemann, Hans Henrik

2015-01-01

This paper investigates Fault-Tolerant Control for closed-loop systems where only coarse models are available and there is lack of actuator and sensor redundancies. The problem is approached in the form of a typical servomotor in closed-loop. A linear model is extracted from input/output data to ...

Pneumatic Variable Series Elastic Actuator.

Science.gov (United States)

Zheng, Hao; Wu, Molei; Shen, Xiangrong

2016-08-01

Inspired by human motor control theory, stiffness control is highly effective in manipulation and human-interactive tasks. The implementation of stiffness control in robotic systems, however, has largely been limited to closed-loop control, and suffers from multiple issues such as limited frequency range, potential instability, and lack of contribution to energy efficiency. Variable-stiffness actuator represents a better solution, but the current designs are complex, heavy, and bulky. The approach in this paper seeks to address these issues by using pneumatic actuator as a variable series elastic actuator (VSEA), leveraging the compressibility of the working fluid. In this work, a pneumatic actuator is modeled as an elastic element with controllable stiffness and equilibrium point, both of which are functions of air masses in the two chambers. As such, for the implementation of stiffness control in a robotic system, the desired stiffness/equilibrium point can be converted to the desired chamber air masses, and a predictive pressure control approach is developed to control the timing of valve switching to obtain the desired air mass while minimizing control action. Experimental results showed that the new approach in this paper requires less expensive hardware (on-off valve instead of proportional valve), causes less control action in implementation, and provides good control performance by leveraging the inherent dynamics of the actuator.

Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

KAUST Repository

Rawashdeh, E.; Karam, A.; Foulds, Ian G.

2012-01-01

This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

Characterization of kink actuators as compared to traditional chevron shaped Bent-Beam electrothermal actuators

KAUST Repository

Rawashdeh, E.

2012-07-06

This paper compares the design and performance of kink actuators, a modified version of the bent-beam thermal actuator, to the standard chevron-shaped designs. A variety of kink and chevron actuator designs were fabricated from polysilicon. While the actuators were electrically probed, these designs were tested using a probe station connected to a National Instruments (NI) controller that uses LabVIEW to extract the displacement results via image processing. The displacement results were then used to validate the thermal-electric-structural simulations produced by COMSOL. These results, in turn, were used to extract the stiffness for both actuator types. The data extracted show that chevron actuators can have larger stiffness values with increasing offsets, but at the cost of lower amplification factors. In contrast, kink actuators showed a constant stiffness value equivalent to the chevron actuator with the highest amplification factor. The kink actuator also had larger amplification factors than chevrons at all designs tested. Therefore, kink actuators are capable of longer throws at lower power levels than the standard chevron designs.

Modeling and test of a kinaesthetic actuator based on MR fluid for haptic applications.

Science.gov (United States)

Yang, Tae-Heon; Koo, Jeong-Hoi; Kim, Sang-Youn; Kwon, Dong-Soo

2017-03-01

Haptic display units have been widely used for conveying button sensations to users, primarily employing vibrotactile actuators. However, the human feeling for pressing buttons mainly relies on kinaesthetic sensations (rather than vibrotactile sensations), and little studies exist on small-scale kinaesthetic haptic units. Thus, the primary goals of this paper are to design a miniature kinaesthetic actuator based on Magneto-Rheological (MR) fluid that can convey various button-clicking sensations and to experimentally evaluate its haptic performance. The design focuses of the proposed actuator were to produce sufficiently large actuation forces (resistive forces) for human users in a given size constraint and to offer a wide range of actuation forces for conveying vivid haptic sensations to users. To this end, this study first performed a series of parametric studies using mathematical force models for multiple operating modes of MR fluid in conjunction with finite element electromagnetism analysis. After selecting design parameters based on parametric studies, a prototype actuator was constructed, and its performance was evaluated using a dynamic mechanical analyzer. It measured the actuator's resistive force with a varying stroke (pressed depth) up to 1 mm and a varying input current from 0 A to 200 mA. The results show that the proposed actuator creates a wide range of resistive forces from around 2 N (off-state) to over 9.5 N at 200 mA. In order to assess the prototype's performance in the terms of the haptic application prospective, a maximum force rate was calculated to determine just noticeable difference in force changes for the 1 mm stoke of the actuator. The results show that the force rate is sufficient to mimic various levels of button sensations, indicating that the proposed kinaesthetic actuator can offer a wide range of resistive force changes that can be conveyed to human operators.

An under-actuated origami gripper with adjustable stiffness joints for multiple grasp modes

Science.gov (United States)

Firouzeh, Amir; Paik, Jamie

2017-05-01

Under-actuated robots offer multiple degrees of freedom without much added complexity to the actuation and control. Utilizing adjustable stiffness joints in these robots allows us to control their stable configurations and their mode of interaction with the environment. In this paper, we present the design of tendon-driven robotic origami (robogami) joints with adjustable stiffness. The proposed designs allow us to place joints along any direction in the plane of the robot and in the normal direction to the plane. The layer-by-layer manufacturing of robogamis facilitates the design and manufacturing of robots with different arrangement of joints for different applications. We use thermally activated shape memory polymer to control the joint stiffness. The manufacturing of the polymer layer is compatible with the layer-by-layer manufacturing process of the robogamis which results in scalable and customizable robots. To demonstrate, we prototyped an under-actuated gripper with three fingers and only one input actuation. The grasp mode of the gripper is set by adjusting the configuration of the locked joints and modulating the stiffness of the active joints. We present a model to estimate the configuration and the contact forces of the gripper at different settings that will assist us in design and control of future generation of under-actuated robogamis.

Electrically controllable twisted-coiled artificial muscle actuators using surface-modified polyester fibers

Science.gov (United States)

Park, Jungwoo; Yoo, Ji Wang; Seo, Hee Won; Lee, Youngkwan; Suhr, Jonghwan; Moon, Hyungpil; Koo, Ja Choon; Ryeol Choi, Hyouk; Hunt, Robert; Kim, Kwang Jin; Kim, Soo Hyun; Nam, Jae-Do

2017-03-01

As a new class of thermally activated actuators based on polymeric fibers, we investigated polyethylene terephthalate (PET) yarns for the development of a twisted-coiled polymer fiber actuator (TCA). The PET yarn TCA exhibited the maximum linear actuation up to 8.9% by external heating at above the glass transition temperature, 160 °C-180 °C. The payload of the actuator was successfully correlated with the preload and training-load conditions by an empirical equation. Furthermore, the PET-based TCA was electrically driven by Joule heating after the PET surface was metallization with silver. For the fast and precise control of PET yarn TCA, electroless silver plating was conducted to form electrical conductive layers on the PET fiber surface. The silver plated PET-based TCA was tested by Joule heating and the tensile actuation was increased up to 12.1% (6 V) due to the enhanced surface hardness and slippage of PET fibers. Overall, silver plating of the polymeric yarn provided a fast actuation speed and enhanced actuation performance of the TCA actuator by Joule heating, providing a great potential for being used in artificial muscle for biomimetic machines including robots, industrial actuators and powered exoskeletons.

Vibration analysis of a functionally graded piezoelectric cylindrical actuator

International Nuclear Information System (INIS)

Zhang, T T; Shi, Z F; Spencer, B F Jr

2008-01-01

This paper focuses on the response of a functionally graded piezoelectric cylindrical actuator placed in a harmonic electric field based on elastic membrane theory and shell theory. The actuator is polarized in the radial direction with its piezoelectric coefficient d 31 varying linearly along the axial direction. In the present investigation, non-dimensional expressions are introduced, and analytical solutions for this class of actuator are obtained. The results provided in the present study are compared with other investigations, with good agreement being found. The major differences between a functionally graded actuator and an actuator with homogeneous material properties are identified, and the advantages of the former are demonstrated. In the last section of this paper, limitations of membrane theory and shell theory models are discussed

The Effects of Sweeping Jet Actuator Parameters on Flow Separation Control

Science.gov (United States)

Koklu, Mehti

2015-01-01

A parametric experimental study was performed with sweeping jet actuators (fluidic oscillators) to determine their effectiveness in controlling flow separation on an adverse pressure gradient ramp. Actuator parameters that were investigated include blowing coefficients, operation mode, pitch and spreading angles, streamwise location, aspect ratio, and scale. Surface pressure measurements and surface oil flow visualization were used to characterize the effects of these parameters on the actuator performance. 2D Particle Image Velocimetry measurements of the flow field over the ramp and hot-wire measurements of the actuator's jet flow were also obtained for selective cases. In addition, the sweeping jet actuators were compared to other well-known flow control techniques such as micro-vortex generators, steady blowing, and steady vortex-generating jets. The results confirm that the sweeping jet actuators are more effective than steady blowing and steady vortex-generating jets. The results also suggest that an actuator with a larger spreading angle placed closer to the location where the flow separates provides better performance. For the cases tested, an actuator with an aspect ratio, which is the width/depth of the actuator throat, of 2 was found to be optimal. For a fixed momentum coefficient, decreasing the aspect ratio to 1 produced weaker vortices while increasing the aspect ratio to 4 reduced coverage area. Although scaling down the actuator (based on the throat dimensions) from 0.25 inch x 0.125 inch to 0.15 inch x 0.075 inch resulted in similar flow control performance, scaling down the actuator further to 0.075 inch x 0.0375 inch reduced the actuator efficiency by reducing the coverage area and the amount of mixing in the near-wall region. The results of this study provide insight that can be used to design and select the optimal sweeping jet actuator configuration for flow control applications.

Use of piezoelectric actuators in active vibration control of rotating machinery

Science.gov (United States)

Lin, Reng Rong; Palazzolo, Alan B.; Kascak, Albert F.; Montague, Gerald

1990-01-01

Theoretical and test results for the development of piezoelectric-actuator-based active vibration control (AVC) are presented. The evolution of this technology starts with an ideal model of the actuator and progresses to a more sophisticated model where the pushers force the squirrel cage ball bearing supports of a rotating shaft. The piezoelectric pushers consist of a stack of piezoelectric ceramic disks that are arranged on top of one another and connected in parallel electrically. This model consists of a prescribed displacement that is proportional to the input voltage and a spring that represents the stiffness of the stack of piezoelectric disks. System tests were carried out to stabilize the AVC system, verify its effectiveness in controlling vibration, and confirm the theory presented.

An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology.

Science.gov (United States)

Liu, Guojun; Zhang, Yanyan; Liu, Jianfang; Li, Jianqiao; Tang, Chunxiu; Wang, Tengfei; Yang, Xuhao

2016-01-01

An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT) actuation and electrorheological fluids (ERFs) control technology is presented. The actuator consists of actuation unit (PZT stack pump), fluid control unit (ERFs valve), and execution unit (hydraulic actuator). In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type) of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

An Unconventional Inchworm Actuator Based on PZT/ERFs Control Technology

Directory of Open Access Journals (Sweden)

Guojun Liu

2016-01-01

Full Text Available An unconventional inchworm actuator for precision positioning based on piezoelectric (PZT actuation and electrorheological fluids (ERFs control technology is presented. The actuator consists of actuation unit (PZT stack pump, fluid control unit (ERFs valve, and execution unit (hydraulic actuator. In view of smaller deformation of PZT stack, a new structure is designed for actuation unit, which integrates the advantages of two modes (namely, diaphragm type and piston type of the volume changing of pump chamber. In order to improve the static shear yield strength of ERFs, a composite ERFs valve is designed, which adopts the series-parallel plate compound structure. The prototype of the inchworm actuator has been designed and manufactured in the lab. Systematic test results indicate that the displacement resolution of the unconventional inchworm actuator reaches 0.038 μm, and the maximum driving force and velocity are 42 N, 14.8 mm/s, respectively. The optimal working frequency for the maximum driving velocity is 120 Hz. The complete research and development processes further confirm the feasibility of developing a new type of inchworm actuator with high performance based on PZT actuation and ERFs control technology, which provides a reference for the future development of a new type of actuator.

Feedback/feedforward control of hysteresis-compensated piezoelectric actuators for high-speed scanning applications

International Nuclear Information System (INIS)

Liu, Yanfang; Shan, Jinjun; Gabbert, Ulrich

2015-01-01

This paper presents the control system design for a piezoelectric actuator (PEA) for a high-speed trajectory scanning application. First nonlinear hysteresis is compensated for by using the Maxwell resistive capacitor model. Then the linear dynamics of the hysteresis-compensated piezoelectric actuator are identified. A proportional plus integral (PI) controller is designed based on the linear system, enhanced by feedforward hysteresis compensation. It is found that the feedback controller does not always improve tracking accuracy. When the input frequency exceeds a certain value, feedforward control only may result in better control performance. Experiments are conducted, and the results demonstrate the effectiveness of the proposed control approach. (paper)

High speed hydraulically-actuated operating system for an electric circuit breaker

Science.gov (United States)

Iman, Imdad

1983-06-07

This hydraulically-actuated operating system comprises a cylinder, a piston movable therein in an opening direction to open a circuit breaker, and an accumulator for supplying pressurized liquid to a breaker-opening piston-actuating space within the cylinder. A normally-closed valve between the accumulator and the actuating space is openable to allow pressurized liquid from the accumulator to flow through the valve into the actuating space to drive the piston in an opening direction. A dashpotting mechanism operating separately from the hydraulic actuating system is provided, thereby reducing flow restriction interference with breaker opening.

Neural networks based identification and compensation of rate-dependent hysteresis in piezoelectric actuators

International Nuclear Information System (INIS)

Zhang, Xinliang; Tan, Yonghong; Su, Miyong; Xie, Yangqiu

2010-01-01

This paper presents a method of the identification for the rate-dependent hysteresis in the piezoelectric actuator (PEA) by use of neural networks. In this method, a special hysteretic operator is constructed from the Prandtl-Ishlinskii (PI) model to extract the changing tendency of the static hysteresis. Then, an expanded input space is constructed by introducing the proposed hysteretic operator to transform the multi-valued mapping of the hysteresis into a one-to-one mapping. Thus, a feedforward neural network is applied to the approximation of the rate-independent hysteresis on the constructed expanded input space. Moreover, in order to describe the rate-dependent performance of the hysteresis, a special hybrid model, which is constructed by a linear auto-regressive exogenous input (ARX) sub-model preceded with the previously obtained neural network based rate-independent hysteresis sub-model, is proposed. For the compensation of the effect of the hysteresis in PEA, the PID feedback controller with a feedforward hysteresis compensator is developed for the tracking control of the PEA. Thus, a corresponding inverse model based on the proposed modeling method is developed for the feedforward hysteresis compensator. Finally, both simulations and experimental results on piezoelectric actuator are presented to verify the effectiveness of the proposed approach for the rate-dependent hysteresis.

Frequency-weighted feedforward control for dynamic compensation in ionic polymer–metal composite actuators

International Nuclear Information System (INIS)

Shan, Yingfeng; Leang, Kam K

2009-01-01

Ionic polymer–metal composites (IPMCs) are innovative materials that offer combined sensing and actuating ability in lightweight and flexible package. IPMCs have been exploited in robotics and a wide variety of biomedical devices, for example, as sensors for teleoperation, as actuators for positioning in active endoscopy, as fins for propelling aquatic robots, and as an injector for drug delivery. In the actuation mode, one of the main challenges is precise position control. In particular, IPMC actuators exhibit relaxation behavior and nonlinearities; and at relatively high operating frequencies dynamic effects limit accuracy and positioning bandwidth. A frequency-weighted feedforward controller is designed to account for the IPMC's structural dynamics to enable fast positioning. The control method is applied to a custom-made Nafion-based IPMC actuator. The controller takes into account the magnitude of the control input to avoid generating excessively large voltages which can damage the IPMC actuator. To account for unmodeled effects not captured by the dynamics model, a feedback controller is integrated with the feedforward controller. Experimental results show a significant improvement in the tracking performance when feedforward control is used. For instance, the feedforward controller shows over 75% reduction in the tracking error compared to the case without feedforward compensation. Finally, the integrated feedforward and feedback control system reduces the tracking error to less than 10% for tracking an 18-Hz triangle-like trajectory. Some of the advantages of feedforward control as well as its limitations are also discussed

Manufacturing of ionic polymer-metal composites (IPMCs) that can actuate into complex curves

Science.gov (United States)

Stoimenov, Boyko L.; Rossiter, Jonathan M.; Mukai, Toshiharu

2007-04-01

Ionic polymer-metal composites (IPMC) are soft actuators with potential applications in the fields of medicine and biologically inspired robotics. Typically, an IPMC bends with approximately constant curvature when voltage is applied to it. More complex shapes were achieved in the past by pre-shaping the actuator or by segmentation and separate actuation of each segment. There are many applications for which fully independent control of each segment of the IPMC is not required and the use of external wiring is objectionable. In this paper we propose two key elements needed to create an IPMC, which can actuate into a complex curve. The first is a connection between adjacent segments, which enables opposite curvature. This can be achieved by reversing the polarity applied on each side of the IPMC, for example by a through-hole connection. The second key element is a variable curvature segment. The segment is designed to bend with any fraction of its full bending ability under given electrical input by changing the overlap of opposite charge electrodes. We demonstrated the usefulness of these key elements in two devices. One is a bi-stable buckled IPMC beam, also used as a building block in a linear actuator device. The other one is an IPMC, actuating into an S-shaped curve with gradually increasing curvature near the ends. The proposed method of manufacturing holds promise for a wide range of new applications of IPMCs, including applications in which IPMCs are used for sensing.

Modeling of a partially debonded piezoelectric actuator in smart composite laminates

International Nuclear Information System (INIS)

Huang, Bin; Soo Kim, Heung; Ho Yoon, Gil

2015-01-01

A partially debonded piezoelectric actuator in smart composite laminates was modeled using an improved layerwise displacement field and Heaviside unit step functions. The finite element method with four node plate element and the extended Hamilton principle were used to derive the governing equation. The effects of actuator debonding on the smart composite laminate were investigated in both the frequency and time domains. The frequency and transient responses were obtained using the mode superposition method and the Newmark time integration algorithm, respectively. Two partial actuator debonding cases were studied to investigate the debonding effects on the actuation capability of the piezoelectric actuator. The effect of actuator debonding on the natural frequencies was subtler, but severe reductions of the actuation ability were observed in both the frequency and time responses, especially in the edge debonded actuator case. The results provided confirmation that the proposed modeling could be used in virtual experiments of actuator failure in smart composite laminates. (paper)

Sector-condition-based results for adaptive control and synchronization of chaotic systems under input saturation

International Nuclear Information System (INIS)

Iqbal, Muhammad; Rehan, Muhammad; Hong, Keum-Shik; Khaliq, Abdul; Saeed-ur-Rehman

2015-01-01

This paper addresses the design of adaptive feedback controllers for two problems (namely, stabilization and synchronization) of chaotic systems with unknown parameters by considering input saturation constraints. A novel generalized sector condition is developed to deal with the saturation nonlinearities for synthesizing the nonlinear and the adaptive controllers for the stabilization and synchronization control objectives. By application of the proposed sector condition and rigorous regional stability analysis, control and adaptation laws are formulated to guarantee local stabilization of a nonlinear system under actuator saturation. Further, simple control and adaptation laws are developed to synchronize two chaotic systems under uncertain parameters and input saturation nonlinearity. Numerical simulation results for Rössler and FitzHugh–Nagumo models are provided to demonstrate the effectiveness of the proposed adaptive stabilization and synchronization control methodologies

Analysis of a spherical permanent magnet actuator

International Nuclear Information System (INIS)

Wang, J.; Jewell, G.W.; Howe, D.

1997-01-01

This paper describes a new form of actuator with a spherical permanent magnet rotor and a simple winding arrangement, which is capable of a high specific torque by utilizing a rare-earth permanent magnet. The magnetic-field distribution is established using an analytical technique formulated in spherical coordinates, and the results are validated by finite element analysis. The analytical field solution allows the prediction of the actuator torque and back emf in closed forms. In turn, these facilitate the characterization of the actuator and provide a firm basis for design optimization, system dynamic modeling, and closed-loop control law development. copyright 1997 American Institute of Physics

Fast force actuators for LSST primary/tertiary mirror

Science.gov (United States)

Hileman, Edward; Warner, Michael; Wiecha, Oliver

2010-07-01

The very short slew times and resulting high inertial loads imposed upon the Large Synoptic Survey Telescope (LSST) create new challenges to the primary mirror support actuators. Traditionally large borosilicate mirrors are supported by pneumatic systems, which is also the case for the LSST. These force based actuators bear the weight of the mirror and provide active figure correction, but do not define the mirror position. A set of six locating actuators (hardpoints) arranged in a hexapod fashion serve to locate the mirror. The stringent dynamic requirements demand that the force actuators must be able to counteract in real time for dynamic forces on the hardpoints during slewing to prevent excessive hardpoint loads. The support actuators must also maintain the prescribed forces accurately during tracking to maintain acceptable mirror figure. To meet these requirements, candidate pneumatic cylinders incorporating force feedback control and high speed servo valves are being tested using custom instrumentation with automatic data recording. Comparative charts are produced showing details of friction, hysteresis cycles, operating bandwidth, and temperature dependency. Extremely low power actuator controllers are being developed to avoid heat dissipation in critical portions of the mirror and also to allow for increased control capabilities at the actuator level, thus improving safety, performance, and the flexibility of the support system.

Fast electrochemical actuator

International Nuclear Information System (INIS)

Uvarov, I V; Postnikov, A V; Svetovoy, V B

2016-01-01

Lack of fast and strong microactuators is a well-recognized problem in MEMS community. Electrochemical actuators can develop high pressure but they are notoriously slow. Water electrolysis produced by short voltage pulses of alternating polarity can overcome the problem of slow gas termination. Here we demonstrate an actuation regime, for which the gas pressure is relaxed just for 10 μs or so. The actuator consists of a microchamber filled with the electrolyte and covered with a flexible membrane. The membrane bends outward when the pressure in the chamber increases. Fast termination of gas and high pressure developed in the chamber are related to a high density of nanobubbles in the chamber. The physical processes happening in the chamber are discussed so as problems that have to be resolved for practical applications of this actuation regime. The actuator can be used as a driving engine for microfluidics. (paper)

Electro-actuation characteristics of Cl2 and SF6 plasma-treated IPMC actuators

International Nuclear Information System (INIS)

Saher, Saim; Kim, Woojin; Moon, Sungwon; Jin Kim, H; Kim, Yong Hyup

2010-01-01

This paper describes plasma treatments that improve the actuation properties by modifying the surface morphology of ionic polymer metal composites (IPMC). The proposed Cl 2 and SF 6 plasmas change the surface appearance of the electroactive polymer, and scanning electron microscopy (SEM) of the plasma-treated surfaces reveals the development of round and cone-shaped microstructures. After electroless chemical metal plating, these microstructures significantly alter the characteristics of the IPMC electrode. In plasma-treated IPMCs, the densely packed platinum nanoparticles have produced a relatively thick electrode layer. This configuration has led to the improvement in the electrical properties of the IPMC: surface resistance is noticeably decreased, whereas electrical capacitance is increased. These changes in the electrical properties have considerably enhanced the actuation parameters: displacement, force and operational life are increased by more than three times relative to the conventional IPMC. Our experimental data suggest a relationship between the IPMC actuator's electrical properties and actuation parameters: actuators with lower surface resistance generate large deflection and actuators with higher capacitance generate large actuation force. The actuation tests including coin lifting suggests the potential of the modified IPMC for artificial muscle applications

Design method for marine direct drive volume control ahead actuator

Directory of Open Access Journals (Sweden)

WANG Haiyang

2018-02-01

Full Text Available [Objectives] In order to reduce the size, weight and auxiliary system configuration of marine ahead actuators, this paper proposes a kind of direct drive volume control electro-hydraulic servo ahead actuator. [Methods] The protruding and indenting control of the servo oil cylinder are realized through the forward and reverse of the bidirectional working gear pump, and the flow matching valve implements the self-locking of the ahead actuator in the target position. The mathematical model of the ahead actuator is established, and an integral separation fuzzy PID controller designed. On this basis, using AMESim software to build a simulation model of the ahead actuator, and combined with testing, this paper completes an analysis of the control strategy research and dynamic and static performance of the ahead actuator. [Results] The experimental results agree well with the simulation results and verify the feasibility of the ahead actuator's design. [Conclusions] The research results of this paper can provide valuable references for the integration and miniaturization design of marine ahead actuators.

Magnetostatic torsional actuator with embedded nickel structures for the improvement of driving force and wobble motion

International Nuclear Information System (INIS)

Tang, Tsung-Lin; Fang, Weileun

2011-01-01

This study demonstrates the magnetostatic torsional actuator consisting in a Si–Ni compound frame to significantly improve the driving force. The present design has three merits: (1) it employs a Si mold to simultaneously electroplate/pattern thick Ni, and the Ni and Si structures respectively provide magnetostatic force and superior mechanical properties, (2) the embedded Ni structures not only increase the ferromagnetic material volume but also enhance magnetization strength to enlarge magnetostatic torque, (3) the Si–Ni compound structure, which is nearly symmetric about the torsional axis in the out-of-plane direction, can decrease the moment of inertia and also reduce the wobble motion. In applications, one-axis torsional actuator is implemented and characterized. The experiments show that the Si–Ni compound scanner has an optical scan angle θ optical = 90° with the input power 81 mW. The input power is decreased as compared with the existing scanner. Moreover, the out-of-plane wobble motion is only 44 nm at θ optical = 15°. Compared with the existing designs consisted of asymmetric structures in the out-of-plane direction, such as electroplated film and silicon rib, about the torsional axis, the equivalent eccentric force is reduced nearly two-fold. In short, the proposed design not only increases the driving force but also decreases the wobble motion

Cylindrical Piezoelectric Fiber Composite Actuators

Science.gov (United States)

Allison, Sidney G.; Shams, Qamar A.; Fox, Robert L.

2008-01-01

The use of piezoelectric devices has become widespread since Pierre and Jacques Curie discovered the piezoelectric effect in 1880. Examples of current applications of piezoelectric devices include ultrasonic transducers, micro-positioning devices, buzzers, strain sensors, and clocks. The invention of such lightweight, relatively inexpensive piezoceramic-fiber-composite actuators as macro fiber composite (MFC) actuators has made it possible to obtain strains and displacements greater than those that could be generated by prior actuators based on monolithic piezoceramic sheet materials. MFC actuators are flat, flexible actuators designed for bonding to structures to apply or detect strains. Bonding multiple layers of MFC actuators together could increase force capability, but not strain or displacement capability. Cylindrical piezoelectric fiber composite (CPFC) actuators have been invented as alternatives to MFC actuators for applications in which greater forces and/or strains or displacements may be required. In essence, a CPFC actuator is an MFC or other piezoceramic fiber composite actuator fabricated in a cylindrical instead of its conventional flat shape. Cylindrical is used here in the general sense, encompassing shapes that can have circular, elliptical, rectangular or other cross-sectional shapes in the planes perpendicular to their longitudinal axes.

Actuators for smart applications

NARCIS (Netherlands)

Paternoster, Alexandre; de Boer, Andries; Loendersloot, Richard; Akkerman, Remko; D. Brei,; M. Frecker,

2010-01-01

Actuator manufacturers are developing promising technologies which meet high requirements in performance, weight and power consumption. Conventionally, actuators are characterized by their displacement and load performance. This hides the dynamic aspects of those actuation solutions. Work per weight

Dynamic actuation of a novel laser-processed NiTi linear actuator

International Nuclear Information System (INIS)

Pequegnat, A; Daly, M; Wang, J; Zhou, Y; Khan, M I

2012-01-01

A novel laser processing technique, capable of locally modifying the shape memory effect, was applied to enhance the functionality of a NiTi linear actuator. By altering local transformation temperatures, an additional memory was imparted into a monolithic NiTi wire to enable dynamic actuation via controlled resistive heating. Characterizations of the actuator load, displacement and cyclic properties were conducted using a custom-built spring-biased test set-up. Monotonic tensile testing was also implemented to characterize the deformation behaviour of the martensite phase. Observed differences in the deformation behaviour of laser-processed material were found to affect the magnitude of the active strain. Furthermore, residual strain during cyclic actuation testing was found to stabilize after 150 cycles while the recoverable strain remained constant. This laser-processed actuator will allow for the realization of new applications and improved control methods for shape memory alloys. (paper)

Design and Control of a Pneumatically Actuated Transtibial Prosthesis.

Science.gov (United States)

Zheng, Hao; Shen, Xiangrong

2015-04-01

This paper presents the design and control of a pneumatically actuated transtibial prosthesis, which utilizes a pneumatic cylinder-type actuator to power the prosthetic ankle joint to support the user's locomotion. The pneumatic actuator has multiple advantages over the traditional electric motor, such as light weight, low cost, and high power-to-weight ratio. The objective of this work is to develop a compact and lightweight transtibial prosthesis, leveraging the multiple advantages provided by this highly competitive actuator. In this paper, the design details of the prosthesis are described, including the determination of performance specifications, the layout of the actuation mechanism, and the calculation of the torque capacity. Through the authors' design calculation, the prosthesis is able to provide sufficient range of motion and torque capacity to support the locomotion of a 75 kg individual. The controller design is also described, including the underlying biomechanical analysis and the formulation of the finite-state impedance controller. Finally, the human subject testing results are presented, with the data indicating that the prosthesis is able to generate a natural walking gait and sufficient power output for its amputee user.

Control of a flexible beam actuated by macro-fiber composite patches: I. Modeling and feedforward trajectory control

International Nuclear Information System (INIS)

Schröck, Johannes; Meurer, Thomas; Kugi, Andreas

2011-01-01

This paper considers a systematic approach for motion planning and feedforward control design for a flexible cantilever actuated by piezoelectric macro-fiber composite (MFC) patches. For accurate feedforward tracking control, special attention has to be paid to the inherent nonlinear hysteresis and creep behavior of these actuators. In order to account for these effects an appropriate compensator is applied which allows us to perform the tracking controller design on the basis of a linear infinite-dimensional model. A detailed analysis of the nonlinear actuator behavior as well as the compensator design and the overall experimental validation is presented in the companion paper (Schröck et al 2011 Smart Mater. Struct. 20 015016). The governing equations of motion of the hysteresis and creep compensated cantilever are determined by means of the extended Hamilton's principle. This allows us to consider the influence of the bonded patch actuators on the mechanical properties of the underlying beam structure in a straightforward manner and results in a model with spatially varying system parameters. For the solution of the motion planning and feedforward control problem a flatness-based methodology is proposed. In a first step, the infinite-dimensional system of the MFC-actuated flexible cantilever is approximated by a finite-dimensional model, where all system variables, i.e. the states, input and output, can be parameterized in terms of a so-called flat output. In a second step, it is shown by numerical simulations that these parameterizations converge with increasing system order of the finite-dimensional model such that the feedforward control input can be directly calculated in order to realize prescribed output trajectories

Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

Science.gov (United States)

Lu, Jun; Kim, Sang-Gyun; Lee, Sunwoo; Oh, Il-Kwon

2008-08-01

In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on.

Fabrication and actuation of electro-active polymer actuator based on PSMI-incorporated PVDF

International Nuclear Information System (INIS)

Lu, Jun; Oh, Il-Kwon; Kim, Sang-Gyun; Lee, Sunwoo

2008-01-01

In this study, an ionic networking membrane (INM) of poly(styrene-alt-maleimide) (PSMI)-incorporated poly(vinylidene fluoride) (PVDF) was applied to fabricate electro-active polymer. Based on the same original membrane of PSMI-incorporated PVDF, various samples of INM actuator were prepared for different reduction times with the electroless-plating technique. The as-prepared INM actuators were tested in terms of surface resistance, platinum morphology, resonance frequency, tip displacement, current and blocked force, and their performances were compared to those of the widely used traditional Nafion actuator. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that much smaller and more uniform platinum particles were formed on the surfaces of the INM actuators as well as within their polymer matrix. Although excellent harmonic responses were observed for the newly developed INM actuators, they were found to be sensitive to the applied reduction times during the fabrication. The mechanical displacement of the INM actuator fabricated after the optimum reduction times was much larger than that of its Nafion counterpart of comparable thickness under the stimulus of constant and alternating current voltage. The PSMI-incorporated PVDF actuator can become a promising smart material to be used in the fields of biomimetic robots, biomedical devices, sensors and actuator, haptic interfaces, energy harvesting and so on

Micro-gravity Isolation using only Electro-magnetic Actuators

DEFF Research Database (Denmark)

Vinther, D.; Alminde, Lars; Bisgaard, Morten

in the Sixth Student Parabolic Flight Campaign issued by the European Space Agency (ESA). The system consists of six custom made electro magnetic actuators which acts on the isolated platform based on the designed controller and their input from six accelerometers and six infrared position sensors. From......In this paper the design, construction and test of a free floating micro-gravity isolation platform to reduce the acceleration dose on zero gravity experiments on e.g. the International Space Station (ISS) is discussed. During the project a system is specified and constructed whereupon it is tested...

Micro-gravity Isolation using only Electro-magnetic Actuators

DEFF Research Database (Denmark)

Vinther, D.; Alminde, Lars; Bisgaard, Morten

2004-01-01

in the Sixth Student Parabolic Flight Campaign issued by the European Space Agency (ESA). The system consists of six custom made electro magnetic actuators which acts on the isolated platform based on the designed controller and their input from six accelerometers and six infrared position sensors. >From......In this paper the design, construction and test of a free floating micro-gravity isolation platform to reduce the acceleration dose on zero gravity experiments on e.g. the International Space Station (ISS) is discussed. During the project a system is specified and constructed whereupon it is tested...

Application of computer voice input/output

International Nuclear Information System (INIS)

Ford, W.; Shirk, D.G.

1981-01-01

The advent of microprocessors and other large-scale integration (LSI) circuits is making voice input and output for computers and instruments practical; specialized LSI chips for speech processing are appearing on the market. Voice can be used to input data or to issue instrument commands; this allows the operator to engage in other tasks, move about, and to use standard data entry systems. Voice synthesizers can generate audible, easily understood instructions. Using voice characteristics, a control system can verify speaker identity for security purposes. Two simple voice-controlled systems have been designed at Los Alamos for nuclear safeguards applicaations. Each can easily be expanded as time allows. The first system is for instrument control that accepts voice commands and issues audible operator prompts. The second system is for access control. The speaker's voice is used to verify his identity and to actuate external devices

Magnetic Actuation of Self-Assembled DNA Hinges

Science.gov (United States)

Lauback, S.; Mattioli, K.; Armstrong, M.; Miller, C.; Pease, C.; Castro, C.; Sooryakumar, R.

DNA nanotechnology offers a broad range of applications spanning from the creation of nanoscale devices, motors and nanoparticle templates to the development of precise drug delivery systems. Central to advancing this technology is the ability to actuate or reconfigure structures in real time, which is currently achieved primarily by DNA strand displacement yielding slow actuation times (about 1-10min). Here we exploit superparamagnetic beads to magnetically actuate DNA structures which also provides a system to measure forces associated with molecular interactions. DNA nanodevices are folded using DNA origami, whereby a long single-stranded DNA is folded into a precise compact geometry using hundreds of short oligonucleotides. Our DNA nanodevice is a nanohinge from which rod shaped DNA nanostructures are polymerized into micron-scale filaments forming handles for actuation. By functionalizing one arm of the hinge and the filament ends, the hinge can be attached to a surface while still allowing an arm to rotate and the filaments can be labeled with magnetic beads enabling the hinge to be actuated almost instantaneously by external magnetic fields. These results lay the groundwork to establish real-time manipulation and direct force application of DNA constructs.

Self-Learning Variable Structure Control for a Class of Sensor-Actuator Systems

Science.gov (United States)

Chen, Sanfeng; Li, Shuai; Liu, Bo; Lou, Yuesheng; Liang, Yongsheng

2012-01-01

Variable structure strategy is widely used for the control of sensor-actuator systems modeled by Euler-Lagrange equations. However, accurate knowledge on the model structure and model parameters are often required for the control design. In this paper, we consider model-free variable structure control of a class of sensor-actuator systems, where only the online input and output of the system are available while the mathematic model of the system is unknown. The problem is formulated from an optimal control perspective and the implicit form of the control law are analytically obtained by using the principle of optimality. The control law and the optimal cost function are explicitly solved iteratively. Simulations demonstrate the effectiveness and the efficiency of the proposed method. PMID:22778633

An Intelligent Actuator Fault Reconstruction Scheme for Robotic Manipulators.

Science.gov (United States)

Xiao, Bing; Yin, Shen

2018-02-01

This paper investigates a difficult problem of reconstructing actuator faults for robotic manipulators. An intelligent approach with fast reconstruction property is developed. This is achieved by using observer technique. This scheme is capable of precisely reconstructing the actual actuator fault. It is shown by Lyapunov stability analysis that the reconstruction error can converge to zero after finite time. A perfect reconstruction performance including precise and fast properties can be provided for actuator fault. The most important feature of the scheme is that, it does not depend on control law, dynamic model of actuator, faults' type, and also their time-profile. This super reconstruction performance and capability of the proposed approach are further validated by simulation and experimental results.

A method to estimate the deformation and the absorbed current of an IPMC actuator

Science.gov (United States)

Bonomo, Claudia; Fortuna, Luigi; Giannone, Pietro; Graziani, Salvatore; Strazzeri, Salvatore

2006-03-01

Based on a previous paper presented at EAPAD Conference on 2005 and supported by the European Community by the research project ISAMCO (Ionic polymer metal composite as Sensors and Actuators for Motion COntrol, 2004-2006) inside the sixth Framework Program, the proposed paper goes on describing the results about the characterization of IPMC materials as motion actuators, obtained by using an improved infrared-based system designed, realized and characterised to this aim. The system was required to detect both the IPMC absorbed current and its consequent deflection, under the effect of the applied voltage. The deflection is detected by the IR system, that uses a differential configuration in order to reduce non-linearity, peculiar to IR devices. The measurement system is used to identify and then validate a model, proposed to describe the IPMC actuator behaviour in a wide range of operating conditions. The model was obtained by adopting a grey box approach. By acquiring the signals involved: the applied voltage, the absorbed current and the IPMC displacement, for different inputs such as pulses, sinusoidal waves (with varying frequency and amplitude) and noise, and by post-processing these signals, all the parameters relative to the IPMC actuator were identified and several tests were performed in order to compare the behaviour of the actuator as predicted by the model with the experimental one. The obtained results show a very good accordance between the simulated and the real actuator response, hence represent a good validation of the proposed model.

Piezoelectric line moment actuator for active radiation control from light-weight structures

Science.gov (United States)

Jandak, Vojtech; Svec, Petr; Jiricek, Ondrej; Brothanek, Marek

2017-11-01

This article outlines the design of a piezoelectric line moment actuator used for active structural acoustic control. Actuators produce a dynamic bending moment that appears in the controlled structure resulting from the inertial forces when the attached piezoelectric stripe actuators start to oscillate. The article provides a detailed theoretical analysis necessary for the practical realization of these actuators, including considerations concerning their placement, a crucial factor in the overall system performance. Approximate formulas describing the dependency of the moment amplitude on the frequency and the required electric voltage are derived. Recommendations applicable for the system's design based on both theoretical and empirical results are provided.

Coupling between the Output Force and Stiffness in Different Variable Stiffness Actuators

Directory of Open Access Journals (Sweden)

Amir Jafari

2014-08-01

Full Text Available The fundamental objective in developing variable stiffness actuators is to enable the actuator to deliberately tune its stiffness. This is done through controlling the energy flow extracted from internal power units, i.e., the motors of a variable stiffness actuator (VSA. However, the stiffness may also be unintentionally affected by the external environment, over which, there is no control. This paper analysis the correlation between the external loads, applied to different variable stiffness actuators, and their resultant output stiffness. Different types of variable stiffness actuators have been studied considering springs with different types of nonlinearity. The results provide some insights into how to design the actuator mechanism and nonlinearity of the springs in order to increase the decoupling between the load and stiffness in these actuators. This would significantly widen the application range of a variable stiffness actuator.

Extended DNA Tile Actuators

DEFF Research Database (Denmark)

Kristiansen, Martin; Kryger, Mille; Zhang, Zhao

2012-01-01

A dynamic linear DNA tile actuator is expanded to three new structures of higher complexity. The original DNA actuator was constructed from a central roller strand which hybridizes with two piston strands by forming two half-crossover junctions. A linear expansion of the actuator is obtained...

Bioinspired Smart Actuator Based on Graphene Oxide-Polymer Hybrid Hydrogels.

Science.gov (United States)

Wang, Tao; Huang, Jiahe; Yang, Yiqing; Zhang, Enzhong; Sun, Weixiang; Tong, Zhen

2015-10-28

Rapid response and strong mechanical properties are desired for smart materials used in soft actuators. A bioinspired hybrid hydrogel actuator was designed and prepared by series combination of three trunks of tough polymer-clay hydrogels to accomplish the comprehensive actuation of "extension-grasp-retraction" like a fishing rod. The hydrogels with thermo-creep and thermo-shrinking features were successively irradiated by near-infrared (NIR) to execute extension and retraction, respectively. The GO in the hydrogels absorbed the NIR energy and transformed it into thermo-energy rapidly and effectively. The hydrogel with adhesion or magnetic force was adopted as the "hook" of the hybrid hydrogel actuator for grasping object. The hook of the hybrid hydrogel actuator was replaceable according to applications, even with functional materials other than hydrogels. This study provides an innovative concept to explore new soft actuators through combining response hydrogels and programming the same stimulus.

Improving Delay-Margin of Noncollocated Vibration Control of Piezo-Actuated Flexible Beams via a Fractional-Order Controller

Directory of Open Access Journals (Sweden)

Teerawat Sangpet

2014-01-01

Full Text Available Noncollocated control of flexible structures results in nonminimum-phase systems because the separation between the actuator and the sensor creates an input-output delay. The delay can deteriorate stability of closed-loop systems. This paper presents a simple approach to improve the delay-margin of the noncollocated vibration control of piezo-actuated flexible beams using a fractional-order controller. Results of real life experiments illustrate efficiency of the controller and show that the fractional-order controller has better stability robustness than the integer-order controller.

Electrostatically Driven Nanoballoon Actuator.

Science.gov (United States)

Barzegar, Hamid Reza; Yan, Aiming; Coh, Sinisa; Gracia-Espino, Eduardo; Dunn, Gabriel; Wågberg, Thomas; Louie, Steven G; Cohen, Marvin L; Zettl, Alex

2016-11-09

We demonstrate an inflatable nanoballoon actuator based on geometrical transitions between the inflated (cylindrical) and collapsed (flattened) forms of a carbon nanotube. In situ transmission electron microscopy experiments employing a nanoelectromechanical manipulator show that a collapsed carbon nanotube can be reinflated by electrically charging the nanotube, thus realizing an electrostatically driven nanoballoon actuator. We find that the tube actuator can be reliably cycled with only modest control voltages (few volts) with no apparent wear or fatigue. A complementary theoretical analysis identifies critical parameters for nanotube nanoballoon actuation.

Actuators, transducers and motors based on giant magnetostrictive materials

Energy Technology Data Exchange (ETDEWEB)

Claeyssen, F.; Lhermet, N.; Le Letty, R. [Cedrat Recherche, Meylan (France); Bouchilloux, P. [Magsoft Corporation, 1223 People`s Avenue, New York 12180 (United States)

1997-08-01

Rare earth-iron magnetostrictive alloys, especially Terfenol-D, feature ``giant`` magnetostrains: static strains of 1000-2000 ppm and dynamic strains of 3500 ppm are reported. These strains permit building various actuating devices (actuators, transducers, motors) both at macro and micro scale. The object of the paper is to recall adapted design methods, especially finite element methods such as ATILA, and to review these different kinds of devices studied at Cedrat Recherche, providing both up-dated experimental and numerical results. The presented devices will include several large displacement longitudinal and shear actuators biased using permanent magnets and used either as characterisation devices or as electromechanical actuators (for active damping, for sonar transducers..), a 1 kHz 4 kW Tonpilz-type sonar transducer called the tripode, a 2 N m torque rotating multi-mode motor, a torsion based drift free micro actuator and a wireless linear micromotor. (orig.)

Context-Based Filtering for Assisted Brain-Actuated Wheelchair Driving

Directory of Open Access Journals (Sweden)

Gerolf Vanacker

2007-01-01

Full Text Available Controlling a robotic device by using human brain signals is an interesting and challenging task. The device may be complicated to control and the nonstationary nature of the brain signals provides for a rather unstable input. With the use of intelligent processing algorithms adapted to the task at hand, however, the performance can be increased. This paper introduces a shared control system that helps the subject in driving an intelligent wheelchair with a noninvasive brain interface. The subject's steering intentions are estimated from electroencephalogram (EEG signals and passed through to the shared control system before being sent to the wheelchair motors. Experimental results show a possibility for significant improvement in the overall driving performance when using the shared control system compared to driving without it. These results have been obtained with 2 healthy subjects during their first day of training with the brain-actuated wheelchair.

Experimental/analytical determination of optimal piezoelectric actuator locations on complex structures based on the actuator power factor

OpenAIRE

Bhargava, Adesh

1995-01-01

The actuator power factor is defined as the ratio of the total dissipative mechanical power of a PZT actuator to the total supplied electrical power to the PZT actuator. If measured experimentally, it can be used to optinlize the actuator location and configuration for complex structures. The concept of actuator power factor is based on the ability of an integrated induced strain actuator such as a PZT actuator to transfer supplied electrical energy into structural mechanical energy. For a gi...

Natural fibres actuators for smart bio-inspired hygromorph biocomposites

Science.gov (United States)

Le Duigou, Antoine; Requile, Samuel; Beaugrand, Johnny; Scarpa, Fabrizio; Castro, Mickael

2017-12-01

Hygromorph biocomposite (HBC) actuators make use of the transport properties of plant fibres to generate an out-of-plane displacement when a moisture gradient is present. HBC actuators possess a design based on the bilayer configuration of natural hygromorph actuators (like pine cone, wheat awn, Selaginella lepidophyll). In this work we present a series of design guidelines for HBCs with improved performance, low environmental footprints and high durability in severe environments. We develop a theoretical actuating response (curvature) formulation of maleic anhydride polypropylene (MAPP)/plant fibres based on bimetallic actuators theory. The actuation response is evaluated as a function of the fibre type (flax, jute, kenaf and coir). We demonstrate that the actuation is directly related to the fibre microstructure and its biochemical composition. The jute and flax fibres appear to be the best candidates for use in HBCs. Flax/MAPP and jute/MAPP HBCs exhibit similar actuating behaviours during the sorption phase (amplitude and speed), but different desorption characteristics due to the combined effect of the lumen size, fibre division and biochemical composition on the desorption mechanism. During hygromechanical fatigue tests the jute/MAPP HBCs exhibit a drastic improvement in durability compared to their flax counterparts. We also provide a demonstration on how HBCs can be used to trigger deployment of more complex structures based on Origami and Kirigami designs.

76 FR 11980 - Stakeholder Input: Listening Session to Provide Information and Solicit Suggestions for...

Science.gov (United States)

2011-03-04

... ENVIRONMENTAL PROTECTION AGENCY 40 CFR Chapter I [Docket EPA-HQ-OW-2011-0119; FRL-9275-4] Stakeholder Input: Listening Session to Provide Information and Solicit Suggestions for Regulations... stakeholders. DATES: The listening sessions will be held at 210 Holiday Court, Annapolis, Maryland 21401, on...

A road to practical dielectric elastomer actuators based robotics and mechatronics: discrete actuation

Science.gov (United States)

Plante, Jean-Sébastien; Devita, Lauren M.; Dubowsky, Steven

2007-04-01

Fundamental studies of Dielectric Elastomer Actuators (DEAs) using viscoelastic materials such as VHB 4905/4910 from 3M showed significant advantages at high stretch rates. The film's viscous forces increase actuator life and the short power-on times minimize energy losses through current leakage. This paper presents a design paradigm that exploits these fundamental properties of DEAs called discrete actuation. Discrete actuation uses DEAs at high stretch rates to change the states of robotic or mechatronic systems in discrete steps. Each state of the system is stable and can be maintained without actuator power. Discrete actuation can be used in robotic and mechatronic applications such as manipulation and locomotion. The resolution of such systems increases with the number of discrete states, 10 to 100 being sufficient for many applications. An MRI-guided needle positioning device for cancer treatments and a space exploration robot using hopping for locomotion are presented as examples of this concept.

Core-free rolled actuators for Braille displays using P(VDF-TrFE-CFE)

Science.gov (United States)

Levard, Thomas; Diglio, Paul J.; Lu, Sheng-Guo; Rahn, Christopher D.; Zhang, Q. M.

2012-01-01

Refreshable Braille displays require many small diameter actuators to move the pins. The electrostrictive P(VDF-TrFE-CFE) terpolymer can provide the high strain and actuation force under modest electric fields that are required for this application. In this paper, we develop core-free tubular actuators and integrate them into a 3 × 2 Braille cell. The terpolymer films are solution cast, stretched to 6 μm thick, electroded, laminated into a bilayer, rolled into a 2 mm diameter tube, bonded, and provided with top and bottom contacts. Experimental testing of 17 actuators demonstrates significant strains (up to 4%) and blocking forces (1 N) at moderate electric fields (100 MV m-1). A novel Braille cell is designed and fabricated using six of these actuators.

High-speed tracking control of piezoelectric actuators using an ellipse-based hysteresis model.

Science.gov (United States)

Gu, Guoying; Zhu, Limin

2010-08-01

In this paper, an ellipse-based mathematic model is developed to characterize the rate-dependent hysteresis in piezoelectric actuators. Based on the proposed model, an expanded input space is constructed to describe the multivalued hysteresis function H[u](t) by a multiple input single output (MISO) mapping Gamma:R(2)-->R. Subsequently, the inverse MISO mapping Gamma(-1)(H[u](t),H[u](t);u(t)) is proposed for real-time hysteresis compensation. In controller design, a hybrid control strategy combining a model-based feedforward controller and a proportional integral differential (PID) feedback loop is used for high-accuracy and high-speed tracking control of piezoelectric actuators. The real-time feedforward controller is developed to cancel the rate-dependent hysteresis based on the inverse hysteresis model, while the PID controller is used to compensate for the creep, modeling errors, and parameter uncertainties. Finally, experiments with and without hysteresis compensation are conducted and the experimental results are compared. The experimental results show that the hysteresis compensation in the feedforward path can reduce the hysteresis-caused error by up to 88% and the tracking performance of the hybrid controller is greatly improved in high-speed tracking control applications, e.g., the root-mean-square tracking error is reduced to only 0.34% of the displacement range under the input frequency of 100 Hz.

Robust trajectory tracking control of a dual-arm space robot actuated by control moment gyroscopes

Science.gov (United States)

Jia, Yinghong; Misra, Arun K.

2017-08-01

It is a new design concept to employ control moment gyroscopes (CMGs) as reactionless actuators for space robots. Such actuation has several noticeable advantages such as weak dynamical coupling and low power consumption over traditional joint motor actuation. This paper presents a robust control law for a CMG-actuated space robot in presence of system uncertainties and closed-chain constraints. The control objective is to make the manipulation variables to track the desired trajectories, and reduce the possibility of CMG saturation simultaneously. A reduced-order dynamical equation in terms of independent motion variables is derived using Kane's equations. Desired trajectories of the independent motion variables are derived by minimum-norm trajectory planning algorithm, and an adaptive sliding mode controller with improved adaptation laws is proposed to drive the independent motion variables tracking the desired trajectories. Uniformly ultimate boundedness of the closed loop system is proven using Lyapunov method. The redundancy of the full-order actual control torques is utilized to generate a null torque vector which reduces the possibility of CMG angular momentum saturation while producing no effect on the reduced-order control input. Simulation results demonstrate the effectiveness of the proposed algorithms and the advantage of weak dynamical coupling of the CMG-actuated system.

Torsional actuation with extension-torsion composite coupling and a magnetostrictive actuator

Science.gov (United States)

Bothwell, Christopher M.; Chandra, Ramesh; Chopra, Inderjit

1995-04-01

An analytical-experimental study of using magnetostrictive actuators in conjunction with an extension-torsion coupled composite tube to actuate a rotor blade trailing-edge flap to actively control helicopter vibration is presented. Thin walled beam analysis based on Vlasov theory was used to predict the induced twist and extension in a composite tube with magnetostrictive actuation. The study achieved good correlation between theory and experiment. The Kevlar-epoxy systems showed good correlation between measured and predicted twist values.

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.

Development of electrothermal actuation based planar variable optical attenuators (VOAs)

International Nuclear Information System (INIS)

Lee, Chengkuo; Yeh, J Andrew

2006-01-01

Several sorts of MEMS (Microelectromechanical Systems) based have been demonstrated by using electrostatic actuation scheme up to date. The comb drive and parallel plate are the two most common electrostatic actuators that have been well studied in variable optical attenuator (VOA) applications. In addition to the known retro-reflection type of optical attenuation being realized by our new devices driven by electrothermal actuators in present study, a novel planar tilted mirror with rotational and translation moving capability is proposed by using electrothermal actuators as well. Using electrothermal actuators to provide said planar tilted mirror with rotational and translational displacement has granted us a more efficient way to perform the light attenuation for in-plane structure. The static and transient characteristics of devices operated at ambient room temperature environment show good repeatability and stability

Electrical actuation of dielectric droplets

International Nuclear Information System (INIS)

Kumari, N; Bahadur, V; Garimella, S V

2008-01-01

Electrical actuation of liquid droplets at the microscale offers promising applications in the fields of microfluidics and lab-on-a-chip devices. Much prior research has targeted the electrical actuation of electrically conducting liquid droplets; however, the actuation of dielectric droplets has remained relatively unexplored, despite the advantages associated with the use of a dielectric droplet. This paper presents modeling and experimental results on the electrical actuation of dielectric droplets between two flat plates. A first-order analytical model, based on the energy-minimization principle, is developed to estimate the electrical actuation force on a dielectric droplet as it moves between two flat plates. Two versions of this analytical model are benchmarked for their suitability and accuracy against a detailed numerical model. The actuation force prediction is then combined with available semi-analytical expressions for predicting the forces opposing droplet motion to develop a model that predicts transient droplet motion under electrical actuation. Electrical actuation of dielectric droplets is experimentally demonstrated by moving transformer oil droplets between two flat plates under the influence of an actuation voltage. Droplet velocities and their dependence on the plate spacing and the applied voltage are experimentally measured and showed reasonable agreement with predictions from the models developed

Part-turn gearboxes for electric actuators; Schwenkgetriebe fuer elektrische Stellantriebe

Energy Technology Data Exchange (ETDEWEB)

Herbstritt, M. [Riester (W.) GmbH und Co. KG, Muellheim (Germany)

2002-09-01

Different types of gearboxes provide a useful complement to the electric actuator type ranges. The gearboxes can be combined with the actuators in many ways. Multi-turn actuators, for example, can be turned into part-turn actuators. When using a modular system, a suitable solution for almost any automation task in the field of industrial valves can be found. (orig.) [German] Sinnvoll ergaenzt werden elektrische Stellantriebe fuer Armaturen durch verschiedene Arten von Getrieben. Die Getriebe sind in vielfaeltiger Weise mit den Stellantrieben kombinierbar. So werden beispielsweise aus Drehantrieben Schwenkantriebe. Mit einem Baukasten-System laesst sich so fuer nahezu jede Automatisierungsaufgabe im Bereich der Industriearmaturen eine passende Loesung finden. (orig.)

Telescoping cylindrical piezoelectric fiber composite actuator assemblies

Science.gov (United States)

Allison, Sidney G. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, legal representative, Christopher L. (Inventor); Fox Chattin, legal representative, Melanie L. (Inventor)

2010-01-01

A telescoping actuator assembly includes a plurality of cylindrical actuators in a concentric arrangement. Each cylindrical actuator is at least one piezoelectric fiber composite actuator having a plurality of piezoelectric fibers extending parallel to one another and to the concentric arrangement's longitudinal axis. Each cylindrical actuator is coupled to concentrically-adjacent ones of the cylindrical actuators such that the plurality of cylindrical actuators can experience telescopic movement. An electrical energy source coupled to the cylindrical actuators applies actuation energy thereto to generate the telescopic movement.

A survey on pneumatic muscle actuators modeling

OpenAIRE

Kelasidi, Eleni; Andrikopoulos, Georgios; Nikolakopoulos, George; Manesis, Stamatis

2012-01-01

The aim of this article is to provide a survey on the most popular modeling approaches for Pneumatic Muscle Actuators (PMAs). PMAs are highly non-linear pneumatic actuators where their elongation is proportional to the interval pressure. During the last decade, there has been an increase in the industrial and scientific utilization of PMAs, due to their advantages such as high strength and small weight, while various types of PMAs with different technical characteristics have been appeared in...

A self-adaption compensation control for hysteresis nonlinearity in piezo-actuated stages based on Pi-sigma fuzzy neural network

Science.gov (United States)

Xu, Rui; Zhou, Miaolei

2018-04-01

Piezo-actuated stages are widely applied in the high-precision positioning field nowadays. However, the inherent hysteresis nonlinearity in piezo-actuated stages greatly deteriorates the positioning accuracy of piezo-actuated stages. This paper first utilizes a nonlinear autoregressive moving average with exogenous inputs (NARMAX) model based on the Pi-sigma fuzzy neural network (PSFNN) to construct an online rate-dependent hysteresis model for describing the hysteresis nonlinearity in piezo-actuated stages. In order to improve the convergence rate of PSFNN and modeling precision, we adopt the gradient descent algorithm featuring three different learning factors to update the model parameters. The convergence of the NARMAX model based on the PSFNN is analyzed effectively. To ensure that the parameters can converge to the true values, the persistent excitation condition is considered. Then, a self-adaption compensation controller is designed for eliminating the hysteresis nonlinearity in piezo-actuated stages. A merit of the proposed controller is that it can directly eliminate the complex hysteresis nonlinearity in piezo-actuated stages without any inverse dynamic models. To demonstrate the effectiveness of the proposed model and control methods, a set of comparative experiments are performed on piezo-actuated stages. Experimental results show that the proposed modeling and control methods have excellent performance.

A rotary pneumatic actuator for the actuation of the exoskeleton knee joint

Directory of Open Access Journals (Sweden)

Jobin Varghese

2017-07-01

Full Text Available Rotary pneumatic actuators that are made out of linear one are always best suited for exoskeleton joint actuation due to its inherent power to weight ratio. This work is a modified version of knee actuation system that has already been developed and major modifications are made in order to make it more suitable for human wearing and also to reduce its bulkiness and complexity. The considered actuator system is a rotary actuator where a pulley converts the linear motion of the standard pneumatic piston into the rotary motion. To prove the capability of the actuator, its performance characteristics such as torque and power produced are compared to the required torque and power at the knee joint of the exoskeleton in swing phase and are found to be excellent. The two-way analysis of variance (ANOVA is performed to find the effect of the throat area valve on knee angle. The ANOVA shows the significant effect of the throat area variation on the knee angle flexion made by the proposed actuator. A relationship between the throat area of flow control valve, that is connected to the exit port of the direction control valve, and angular displacement of the knee joint has been formulated. This relationship can be used to design a control system to regulate the mass flow rate of air at the exit and hence the angular velocity of the knee joint can be controlled. Keywords: Driven pulley, Flow control valve, Rotary, Pneumatic cylinder

Elastic Inflatable Actuators for Soft Robotic Applications.

Science.gov (United States)

Gorissen, Benjamin; Reynaerts, Dominiek; Konishi, Satoshi; Yoshida, Kazuhiro; Kim, Joon-Wan; De Volder, Michael

2017-11-01

The 20th century's robotic systems have been made from stiff materials, and much of the developments have pursued ever more accurate and dynamic robots, which thrive in industrial automation, and will probably continue to do so for decades to come. However, the 21st century's robotic legacy may very well become that of soft robots. This emerging domain is characterized by continuous soft structures that simultaneously fulfill the role of robotic link and actuator, where prime focus is on design and fabrication of robotic hardware instead of software control. These robots are anticipated to take a prominent role in delicate tasks where classic robots fail, such as in minimally invasive surgery, active prosthetics, and automation tasks involving delicate irregular objects. Central to the development of these robots is the fabrication of soft actuators. This article reviews a particularly attractive type of soft actuators that are driven by pressurized fluids. These actuators have recently gained traction on the one hand due to the technology push from better simulation tools and new manufacturing technologies, and on the other hand by a market pull from applications. This paper provides an overview of the different advanced soft actuator configurations, their design, fabrication, and applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development, Control, and Evaluation of an Actuated Car Door.

Science.gov (United States)

Strolz, M; Mortl, A; Graf, M; Buss, M

2009-01-01

Actuated car doors are a promising way to increase the convenience of access to cars. We propose an advanced actuation and control concept which can easily be integrated into conventional car doors. By utilizing a linear, nonbackdrivable actuator and various sensors, both automatic and manual door operations are enabled. A discrete state controller ensures a safe operation of the door, including automatic opening and closing. The realization of a supportive, high-quality haptic interaction with the car door for the manual operation is the principal part of our work. Due to the impracticality of a direct measurement of the user interaction force at a car door, we chose impedance control to render the desired dynamics. The impedance was designed to provide a convenient, intuitive, and safe manual handling of the door. We implemented and tested four different impedance control schemes, of which impedance control with actuator force feedback performed best. Two experimental evaluations with 16 and 27 participants revealed a predominant approval of the actuated car door.

A Method for Aileron Actuator Fault Diagnosis Based on PCA and PGC-SVM

Directory of Open Access Journals (Sweden)

Wei-Li Qin

2016-01-01

Full Text Available Aileron actuators are pivotal components for aircraft flight control system. Thus, the fault diagnosis of aileron actuators is vital in the enhancement of the reliability and fault tolerant capability. This paper presents an aileron actuator fault diagnosis approach combining principal component analysis (PCA, grid search (GS, 10-fold cross validation (CV, and one-versus-one support vector machine (SVM. This method is referred to as PGC-SVM and utilizes the direct drive valve input, force motor current, and displacement feedback signal to realize fault detection and location. First, several common faults of aileron actuators, which include force motor coil break, sensor coil break, cylinder leakage, and amplifier gain reduction, are extracted from the fault quadrantal diagram; the corresponding fault mechanisms are analyzed. Second, the data feature extraction is performed with dimension reduction using PCA. Finally, the GS and CV algorithms are employed to train a one-versus-one SVM for fault classification, thus obtaining the optimal model parameters and assuring the generalization of the trained SVM, respectively. To verify the effectiveness of the proposed approach, four types of faults are introduced into the simulation model established by AMESim and Simulink. The results demonstrate its desirable diagnostic performance which outperforms that of the traditional SVM by comparison.

A tubular dielectric elastomer actuator: Fabrication, characterization and active vibration isolation

DEFF Research Database (Denmark)

Sarban, R.; Jones, R. W.; Mace, B. R.

2011-01-01

This contribution reviews the fabrication, characterization and active vibration isolation performance of a core-free rolled tubular dielectric elastomer (DE) actuator, which has been designed and developed by Danfoss PolyPower A/S. PolyPower DE material, PolyPower (TM), is produced in thin sheets...... of 80 mu m thickness with corrugated metallic electrodes on both sides. Tubular actuators are manufactured by rolling the DE sheets in a cylindrical shape. The electromechanical characteristics of such actuators are modeled based on equilibrium pressure equation. The model is validated with experimental...... the dominant dynamic characteristics of the core-free tubular actuator. It has been observed that all actuators have similar dynamic characteristics in a frequency range up to 1 kHz. A tubular actuator is then used to provide active vibration isolation (AVI) of a 250 g mass subject to shaker generated 'ground...

Modeling and control of precision actuators

CERN Document Server

Kiong, Tan Kok

2013-01-01

IntroductionGrowing Interest in Precise ActuatorsTypes of Precise ActuatorsApplications of Precise ActuatorsNonlinear Dynamics and ModelingHysteresisCreepFrictionForce RipplesIdentification and Compensation of Preisach Hysteresis in Piezoelectric ActuatorsSVD-Based Identification and Compensation of Preisach HysteresisHigh-Bandwidth Identification and Compensation of Hysteretic Dynamics in Piezoelectric ActuatorsConcluding RemarksIdentification and Compensation of Frict

Core-free rolled actuators for Braille displays using P(VDF–TrFE–CFE)

International Nuclear Information System (INIS)

Levard, Thomas; Diglio, Paul J; Rahn, Christopher D; Lu, Sheng-Guo; Zhang, Q M

2012-01-01

Refreshable Braille displays require many small diameter actuators to move the pins. The electrostrictive P(VDF–TrFE–CFE) terpolymer can provide the high strain and actuation force under modest electric fields that are required for this application. In this paper, we develop core-free tubular actuators and integrate them into a 3 × 2 Braille cell. The terpolymer films are solution cast, stretched to 6 μm thick, electroded, laminated into a bilayer, rolled into a 2 mm diameter tube, bonded, and provided with top and bottom contacts. Experimental testing of 17 actuators demonstrates significant strains (up to 4%) and blocking forces (1 N) at moderate electric fields (100 MV m −1 ). A novel Braille cell is designed and fabricated using six of these actuators. (fast track communication)

Clean room actuators

Energy Technology Data Exchange (ETDEWEB)

Higuchi, Toshiro

1987-06-01

This report explains on the present status of the clean room actuators including the author's research results. In a clean room, there exists a possibility of dust generation, even when a direct human work is eliminated by the use of robots or automatic machines, from the machines themselves. For this, it is important to develop such clean robots and transfer/positioning mechanism that do not generate dusts, and to develop an actuator and its control technique. Topics described in the report are as follows: 1. Prevention of dust diffusion by means of sealing. 2. Elimination of mechanical contact (Linear induction motor and pneumatic float, linear motor and magnetic attraction float, linear motor and air bearing, and magnetic bearing). 3. Contactless actuator having a positioning mechanism (Use of linear step motor and rotary contactless actuator). (15 figs, 11 refs)

Effects of anchoring and arc structure on the control authority of a rail plasma actuator

International Nuclear Information System (INIS)

Choi, Young-Joon; Gray, Miles; Sirohi, Jayant; Raja, Laxminarayan L

2017-01-01

Experiments were conducted on a rail plasma actuator (RailPAc) with different electrode cross sections (rails or rods) to assess methods to improve the actuation authority, defined as the impulse generated for a given electrical input. The arc was characterized with electrical measurements and high-speed images, while impulse measurements quantified the actuation authority. A RailPAc power supply capable of delivering  ∼1 kA of current at  ∼100 V was connected to rod electrodes (free-floating with circular cross-section) and rail electrodes (flush-mounted in a flat plate with rectangular cross-section). High-speed images show that the rail electrodes cause the arc to anchor itself to the anode electrode and transit in discrete jumps, while rod electrodes permit the arc to transit smoothly without anchoring. The impulse measurements reveal that the anchoring reduces the actuation authority by  ∼21% compared to a smooth transit, and the effect of anchoring can be suppressed by reducing the gap between the rails to 2 mm. The study further demonstrates that if a smooth transit is achieved, the control authority can be increased with a larger gap and larger arc current. In conclusion, the actuation authority of a RailPAc can be maximized by carefully choosing a gap width that prevents anchoring. Further study is warranted to increase the RailPAc actuation authority by introducing multiple turns of wires beneath the RailPAc to augment the induced magnetic field. (paper)

Electrical Actuation Technology Bridging

Science.gov (United States)

Hammond, Monica (Compiler); Sharkey, John (Compiler)

1993-01-01

This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.

Actuator technology and market outlook: where does the actuator move

Directory of Open Access Journals (Sweden)

Aleksanin Sergei Andreevich

2013-11-01

There are made conclusions about the "migration" of demand from hydraulic and pneumatic solutions to electromechanical actuators in the aerospace and manufacturing industries. Identify advantages of electromechanics over more traditional actuators in terms of energy efficiency and reliability. Also identify the most promising areas of the drive technological development.

Single motor–variable stiffness actuator using bistable switching mechanisms for independent motion and stiffness control

NARCIS (Netherlands)

Groothuis, Stefan; Carloni, Raffaella; Stramigioli, Stefano

This paper presents a proof of concept of a variable stiffness actuator (VSA) that uses only one (high power) input motor. In general, VSAs use two (high power) motors to be able to control both the output position and the output stiffness, which possibly results in a heavy, and bulky system. In

Cruise and turning performance of an improved fish robot actuated by piezoceramic actuators

Science.gov (United States)

Nguyen, Quang Sang; Heo, Seok; Park, Hoon Cheol; Goo, Nam Seo; Byun, Doyoung

2009-03-01

The purpose of this study is improvement of a fish robot actuated by four light-weight piezocomposite actuators (LIPCAs). In the fish robot, we developed a new actuation mechanism working without any gear and thus the actuation mechanism was simple in fabrication. By using the new actuation mechanism, cross section of the fish robot became 30% smaller than that of the previous model. Performance tests of the fish robot in water were carried out to measure tail-beat angle, thrust force, swimming speed and turning radius for tail-beat frequencies from 1Hz to 5Hz. The maximum swimming speed of the fish robot was 7.7 cm/s at 3.9Hz tail-beat frequency. Turning experiment showed that swimming direction of the fish robot could be controlled with 0.41 m turning radius by controlling tail-beat angle.

Recent developments on SMA actuators: predicting the actuation fatigue life for variable loading schemes

Science.gov (United States)

Wheeler, Robert W.; Lagoudas, Dimitris C.

2017-04-01

Shape memory alloys (SMAs), due to their ability to repeatably recover substantial deformations under applied mechanical loading, have the potential to impact the aerospace, automotive, biomedical, and energy industries as weight and volume saving replacements for conventional actuators. While numerous applications of SMA actuators have been flight tested and can be found in industrial applications, these actuators are generally limited to non-critical components, are not widely implemented and frequently one-off designs, and are generally overdesigned due to a lack of understanding of the effect of the loading path on the fatigue life and the lack of an accurate method for predicting actuator lifetimes. In recent years, multiple research efforts have increased our understanding of the actuation fatigue process of SMAs. These advances can be utilized to predict the fatigue lives and failure loads in SMA actuators. Additionally, these prediction methods can be implemented in order to intelligently design actuators in accordance with their fatigue and failure limits. In the following paper, both simple and complex thermomechanical loading paths have been considered. Experimental data was utilized from two material systems: equiatomic Nickel-Titanium and Nickelrich Nickel-Titanium.

Actuation Characteristics of 0.15mm Diameter Flexinol® and Biometal ® Wire Actuators for Robotic Applications

Directory of Open Access Journals (Sweden)

Jawaid Daudpoto

2013-01-01

Full Text Available In this paper the actuation properties of two NiTi (Nickel Titanium SMA (Shape Memory Alloy actuators available under the commercial names of Flexinol ® and Biometal ® are investigated and compared with each other. Both actuators have diameter of 0.15mm and transformation temperature of 70 o C. The diameter of 0.15mm is selected because of best combination of force and cooling time. An experimental test rig specially designed and developed by the first author was used to conduct tests on the actuators. Both actuators were tested by supplying actuation voltages of 5 and 5.5V. Actuators were thermomechanically loaded for 100 cycles and their strains were recorded. The results of the tests show that 5.5V actuation resulted in greater strain. It was found from the test results that Biometal ® actuators produced more strain as compared to Flexinol ® actuators for both the actuation voltages. However, the drift results showed that higher strains in Biometal ® are due the permanent deformation of the same. This shows that Flexinol ® actuators possess better actuation characteristics as compared to Biometal ® actuators.

Topological design of compliant smart structures with embedded movable actuators

International Nuclear Information System (INIS)

Wang, Yiqiang; Zhang, Xiaopeng; Kang, Zhan; Luo, Zhen

2014-01-01

In the optimal configuration design of piezoelectric smart structures, it is favorable to use actuation elements with certain predefined geometries from the viewpoint of manufacturability of fragile piezoelectric ceramics in practical applications. However, preserving the exact shape of these embedded actuators and tracking their dynamic motions presents a more challenging research task than merely allowing them to take arbitrary shapes. This paper proposes an integrated topology optimization method for the systematic design of compliant smart structures with embedded movable PZT (lead zirconate titanate) actuators. Compared with most existing studies, which either optimize positions/sizes of the actuators in a given host structure or design the host structure with pre-determined actuator locations, the proposed method simultaneously optimizes the positions of the movable PZT actuators and the topology of the host structure, typically a compliant mechanism for amplifying the small strain stroke. A combined topological description model is employed in the optimization, where the level set model is used to track the movements of the PZT actuators and the independent point-wise density interpolation (iPDI) approach is utilized to search for the optimal topology of the host structure. Furthermore, we define an integral-type constraint function to prevent overlaps between the PZT actuators and between the actuators and the external boundaries of the design domain. Such a constraint provides a unified and explicit mathematical statement of the non-overlap condition for any number of arbitrarily shaped embedded actuators. Several numerical examples are used to demonstrate the effectiveness of the proposed optimization method. (paper)

Investigation of Equivalent Unsprung Mass and Nonlinear Features of Electromagnetic Actuated Active Suspension

Directory of Open Access Journals (Sweden)

Jun Yin

2015-01-01

Full Text Available Electromagnetic actuated active suspension benefits active control and energy harvesting from vibration at the same time. However, the rotary type electromagnetic actuated active suspension introduces a significant extra mass on the unsprung mass due to the inertia of the rotating components of the actuator. The magnitude of the introduced unsprung mass is studied based on a gearbox type actuator and a ball screw type actuator. The geometry of the suspension and the actuator also influence the equivalent unsprung mass significantly. The suspension performance simulation or control logic derived should take this equivalent unsprung mass into account. Besides, an extra force should be compensated due to the nonlinear features of the suspension structure and it is studied. The active force of the actuator should compensate this extra force. The discovery of this paper provides a fundamental for evaluating the rotary type electromagnetic actuated active suspension performance and control strategy derived as well as controlling the electromagnetic actuated active suspension more precisely.

Design and experimental characterization of a NiTi-based, high-frequency, centripetal peristaltic actuator

International Nuclear Information System (INIS)

Borlandelli, E; Scarselli, D; Bettini, P; Morandini, M; Sala, G; Quadrio, M; Nespoli, A; Rigamonti, D; Villa, E

2015-01-01

Development and experimental testing of a peristaltic device actuated by a single shape-memory NiTi wire are described. The actuator is designed to radially shrink a compliant silicone pipe, and must work on a sustained basis at an actuation frequency that is higher than those typical of NiTi actuators. Four rigid, aluminum-made circular sectors are sitting along the pipe circumference and provide the required NiTi wire housing. The aluminum assembly acts as geometrical amplifier of the wire contraction and as heat sink required to dissipate the thermal energy of the wire during the cooling phase. We present and discuss the full experimental investigation of the actuator performance, measured in terms of its ability to reduce the pipe diameter, at a sustained frequency of 1.5 Hz. Moreover, we investigate how the diameter contraction is affected by various design parameters as well as actuation frequencies up to 4 Hz. We manage to make the NiTi wire work at 3% in strain, cyclically providing the designed pipe wall displacement. The actuator performance is found to decay approximately linearly with actuation frequencies up to 4 Hz. Also, the interface between the wire and the aluminum parts is found to be essential in defining the functional performance of the actuator. (paper)

Vibration control for precision manufacturing using piezoelectric actuators

Energy Technology Data Exchange (ETDEWEB)

Martinez, D.R.; Hinnerichs, T.D.; Redmond, J.M.

1995-12-31

Piezoelectric actuators provide high frequency, force, and stiffness capabilities along with reasonable Stroke limits, all of which can be used to increase performance levels in precision manufacturing systems. This paper describes two examples of embedding piezoelectric actuators in structural components for vibration control. One example involves suppressing the self excited chatter phenomenon in the metal cutting process of a milling machine and the other involves damping vibrations induced by rigid body stepping of a photolithography platen. Finite element modeling and analyses are essential for locating and sizing the actuators and permit further simulation studies of the response of the dynamic system. Experimental results are given for embedding piezoelectric actuators in a cantilevered bar configuration, which was used as a surrogate machine tool structure. These results are incorporated into a previously developed milling process simulation and the effect of the control on the cutting process stability diagram is quantified. Experimental results are also given for embedding three piezoelectric actuators in a surrogate photolithography platen to suppress vibrations. These results demonstrate the potential benefit that can be realized by applying advances from the field of adaptive structures to problems in precision manufacturing.

Evaluation of Effective Diaphragm Area for Pneumatic Actuator

International Nuclear Information System (INIS)

Ryu, Hogeun; Han, Bongsub; Seon, Juhyoung

2016-01-01

The purpose of this study is to develop a methodology to calculate the exact effective diaphragm area using the results of diagnostic test to be performed in the evaluation of air operated valve performance. By using this developed methodology in pneumatic actuator performance evaluation, it can be reduce the possible errors arising from effective diaphragm area in the evaluation of performance of air operated valves. The performance assessment for the operability and structural integrity of air operated valves for the domestic nuclear power plant is in progress. One of the important parameters that determine the performance of the air operated valves is the effective diaphragm area of diaphragm type actuator. The effective diaphragm area is the actual area which the air pressure acting on the diaphragm. In general, the effective diaphragm area used for the performance evaluation of pneumatic actuator is provided by the manufacture or the actuator drawing. Flat type diaphragm was showed the difference between the measured value of EDA and the manufacture’s value, in the case of convoluted type diaphragm has showed that the measured value of EDA and manufacture’s value is almost the same. When evaluate a performance of a diaphragm actuator, accurate EDA is to be used because it is an important variable affecting the actuator performance. Particularly in the case of flat type diaphragm which EDA is changed in accordance with the stroke position, by using the EDA evaluation methodology developed in this study to minimize a possible error due to EDA when evaluating the performance of the air actuator

Evaluation of Effective Diaphragm Area for Pneumatic Actuator

Energy Technology Data Exchange (ETDEWEB)

Ryu, Hogeun; Han, Bongsub; Seon, Juhyoung [SOOSAN INDUSTRIES, Seoul (Korea, Republic of)

2016-10-15

The purpose of this study is to develop a methodology to calculate the exact effective diaphragm area using the results of diagnostic test to be performed in the evaluation of air operated valve performance. By using this developed methodology in pneumatic actuator performance evaluation, it can be reduce the possible errors arising from effective diaphragm area in the evaluation of performance of air operated valves. The performance assessment for the operability and structural integrity of air operated valves for the domestic nuclear power plant is in progress. One of the important parameters that determine the performance of the air operated valves is the effective diaphragm area of diaphragm type actuator. The effective diaphragm area is the actual area which the air pressure acting on the diaphragm. In general, the effective diaphragm area used for the performance evaluation of pneumatic actuator is provided by the manufacture or the actuator drawing. Flat type diaphragm was showed the difference between the measured value of EDA and the manufacture’s value, in the case of convoluted type diaphragm has showed that the measured value of EDA and manufacture’s value is almost the same. When evaluate a performance of a diaphragm actuator, accurate EDA is to be used because it is an important variable affecting the actuator performance. Particularly in the case of flat type diaphragm which EDA is changed in accordance with the stroke position, by using the EDA evaluation methodology developed in this study to minimize a possible error due to EDA when evaluating the performance of the air actuator.

Electromechanical response and failure modes of a dielectric elastomer tube actuator with boundary constraints

International Nuclear Information System (INIS)

Zhou, Jianyou; Jiang, Liying; Khayat, Roger E

2014-01-01

As a widely used configuration for dielectric elastomer (DE) actuators, DE tube actuators (or cylindrical actuators) are also found to be susceptible to electromechanical instability (EMI), which may lead to a premature electrical breakdown (EB), and inhibit the potential actuation of DE actuators. This work investigates the electromechanical response of a DE tube actuator with and without boundary constraints to demonstrate an alternative to avoid EMI while achieving large actuation. Our simulation results based on the Gent strain energy model show that the EMI of a DE tube actuator can be eliminated, and larger actuation deformation can be achieved by applying boundary constraints. As a result of these constraints, consideration is also given to the possible mechanical buckling failure that may occur. Mechanisms of possible failure modes of constrained and unconstrained DE tube actuators, such as electromechanical instability, electrical breakdown and mechanical buckling, are elucidated. This paper should provide better theoretical guidance on how to improve the actuation performance of DE actuators, thus leading to the optimal design of DE-based devices. (paper)

Consideration of Optimal Input on Semi-Active Shock Control System

Science.gov (United States)

Kawashima, Takeshi

In press working, unidirectional transmission of mechanical energy is expected in order to maximize the life of the dies. To realize this transmission, the author has developed a shock control system based on the sliding mode control technique. The controller makes a collision-receiving object effectively deform plastically by adjusting the force of the actuator inserted between the colliding objects, while the deformation of the colliding object is held at the necessity minimum. However, the actuator has to generate a large force corresponding to the impulsive force. Therefore, development of such an actuator is a formidable challenge. The author has proposed a semi-active shock control system in which the impulsive force is adjusted by a brake mechanism, although the system exhibits inferior performance. Thus, the author has also designed an actuator using a friction device for semi-active shock control, and proposed an active seatbelt system as an application. The effectiveness has been confirmed by a numerical simulation and model experiment. In this study, the optimal deformation change of the colliding object is theoretically examined in the case that the collision-receiving object has perfect plasticity and the colliding object has perfect elasticity. As a result, the optimal input condition is obtained so that the ratio of the maximum deformation of the collision-receiving object to the maximum deformation of the colliding object becomes the maximum. Additionally, the energy balance is examined.

Optimum Actuator Selection with a Genetic Algorithm for Aircraft Control

Science.gov (United States)

Rogers, James L.

2004-01-01

The placement of actuators on a wing determines the control effectiveness of the airplane. One approach to placement maximizes the moments about the pitch, roll, and yaw axes, while minimizing the coupling. For example, the desired actuators produce a pure roll moment without at the same time causing much pitch or yaw. For a typical wing, there is a large set of candidate locations for placing actuators, resulting in a substantially larger number of combinations to examine in order to find an optimum placement satisfying the mission requirements and mission constraints. A genetic algorithm has been developed for finding the best placement for four actuators to produce an uncoupled pitch moment. The genetic algorithm has been extended to find the minimum number of actuators required to provide uncoupled pitch, roll, and yaw control. A simplified, untapered, unswept wing is the model for each application.

Actuating movement in refined wearables

NARCIS (Netherlands)

Toeters, M.J.; Feijs, L.M.G.

2014-01-01

Nowadays it is quite possible to deploy textiles as sensors and avoid traditional hard sensors. Actuation (movement) turns out more difficult. It is advantageous to combine sensing and actuation, similar to ecological perception theory. Although several actuators are known: SMA, voice coil, motors,

Indirect adaptive fuzzy fault-tolerant tracking control for MIMO nonlinear systems with actuator and sensor failures.

Science.gov (United States)

Bounemeur, Abdelhamid; Chemachema, Mohamed; Essounbouli, Najib

2018-05-10

In this paper, an active fuzzy fault tolerant tracking control (AFFTTC) scheme is developed for a class of multi-input multi-output (MIMO) unknown nonlinear systems in the presence of unknown actuator faults, sensor failures and external disturbance. The developed control scheme deals with four kinds of faults for both sensors and actuators. The bias, drift, and loss of accuracy additive faults are considered along with the loss of effectiveness multiplicative fault. A fuzzy adaptive controller based on back-stepping design is developed to deal with actuator failures and unknown system dynamics. However, an additional robust control term is added to deal with sensor faults, approximation errors, and external disturbances. Lyapunov theory is used to prove the stability of the closed loop system. Numerical simulations on a quadrotor are presented to show the effectiveness of the proposed approach. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

Post-buckled precompressed (PBP) piezoelectric actuators for UAV flight control

Science.gov (United States)

Vos, Roelof; Barrett, Ron; Krakers, Lars; van Tooren, Michel

2006-03-01

This paper presents the use of a new class of flight control actuators employing Post-Buckled Precompressed (PBP) piezoelectric elements in morphing wing Uninhabited Aerial Vehicles (UAVs). The new actuator relies on axial compression to amplify deflections and control forces simultaneously. Two designs employing morphing wing panels based on PBP actuators were conceived. One design employed PBP actuators in a membrane wing panel over the aft 60% of the chord to impose roll control on a 720mm span subscale UAV. This design relied on a change in curvature of the actuators to control the camber of the airfoil. Axial compression of the actuators was ensured by means of rubber bands and increased end rotation levels with almost a factor of two up to +/-13.6° peak-to-peak, with excellent correlation between theory and experiment. Wind tunnel tests quantitatively proved that wing morphing induced roll acceleration levels in excess of 1500 deg/s2. A second design employed PBP actuators in a wing panel with significant thickness, relying on a highly compliant Latex skin to allow for shape deformation and at the same time induce an axial force on the actuators. Bench tests showed that due to the axial compression provided by the skin end rotations were increased with more than a factor of two up to +/-15.8° peak-to-peak up to a break frequency of 34Hz. Compared to conventional electromechanical servoactuaters, the PBP actuators showed a net reduction in flight control system weight, slop and power consumption for minimal part count. Both morphing wing concepts showed that PBP piezoelectric actuators have significant benefits over conventional actuators and can be successfully applied to induce aircraft control.

Conjugated Polymers as Actuators: Modes of Actuation

DEFF Research Database (Denmark)

Skaarup, Steen

2004-01-01

The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

Conjugated polymers as actuators: modes of actuation

DEFF Research Database (Denmark)

Skaarup, Steen

2007-01-01

The physical and chemical properties of conjugated polymers often depend very strongly on the degree of doping with anions or cations. The movement of ions in and out of the polymer matrix as it is redox cycled is also accompanied by mechanical changes. Both the volume and the stiffness can exhibit...... significant differences between the oxidized and reduced states. These effects form the basis of the use of conjugated polymers as actuators (or “artificial muscles”) controllable by a small (1-10 V) voltage. Three basic modes of actuation (bending, linear extension and stiffness change) have been proposed...

A Review of Smart Materials in Tactile Actuators for Information Delivery

Directory of Open Access Journals (Sweden)

Xin Xie

2017-12-01

Full Text Available As the largest organ in the human body, the skin provides the important sensory channel for humans to receive external stimulations based on touch. By the information perceived through touch, people can feel and guess the properties of objects, like weight, temperature, textures, and motion, etc. In fact, those properties are nerve stimuli to our brain received by different kinds of receptors in the skin. Mechanical, electrical, and thermal stimuli can stimulate these receptors and cause different information to be conveyed through the nerves. Technologies for actuators to provide mechanical, electrical or thermal stimuli have been developed. These include static or vibrational actuation, electrostatic stimulation, focused ultrasound, and more. Smart materials, such as piezoelectric materials, carbon nanotubes, and shape memory alloys, play important roles in providing actuation for tactile sensation. This paper aims to review the background biological knowledge of human tactile sensing, to give an understanding of how we sense and interact with the world through the sense of touch, as well as the conventional and state-of-the-art technologies of tactile actuators for tactile feedback delivery.

Characteristics of Response of Piezoelectric Actuators in Electron Flux Excitation

Directory of Open Access Journals (Sweden)

Philip C. Hadinata

2003-11-01

Full Text Available In this paper the working parameters of non-contact strain control for piezoelectric ceramics are evaluated. The piezoelectric material functions as an actuator that transforms electrical into mechanical energy, and the electrical input is carried out by electron flux on the positive surface. The sample is exposed to some quasi-static inputs, and its responses are recorded using strain gages. The data shows faster and more stable response in the positive regime, but significantly slower response with drift in the negative regime. An electron collector is introduced on the positive surface to enhance the response in the negative regime. Theoretical analyses of energy transfer and electron movements is discussed, and a string of working conditions for controlling the surface strain of piezoelectric material are given as conclusions.

Modeling and design of a high-performance hybrid actuator

Science.gov (United States)

Aloufi, Badr; Behdinan, Kamran; Zu, Jean

2016-12-01

This paper presents the model and design of a novel hybrid piezoelectric actuator which provides high active and passive performances for smart structural systems. The actuator is composed of a pair of curved pre-stressed piezoelectric actuators, so-called commercially THUNDER actuators, installed opposite each other using two clamping mechanisms constructed of in-plane fixable hinges, grippers and solid links. A fully mathematical model is developed to describe the active and passive dynamics of the actuator and investigate the effects of its geometrical parameters on the dynamic stiffness, free displacement and blocked force properties. Among the literature that deals with piezoelectric actuators in which THUNDER elements are used as a source of electromechanical power, the proposed study is unique in that it presents a mathematical model that has the ability to predict the actuator characteristics and achieve other phenomena, such as resonances, mode shapes, phase shifts, dips, etc. For model validation, the measurements of the free dynamic response per unit voltage and passive acceleration transmissibility of a particular actuator design are used to check the accuracy of the results predicted by the model. The results reveal that there is a good agreement between the model and experiment. Another experiment is performed to teste the linearity of the actuator system by examining the variation of the output dynamic responses with varying forces and voltages at different frequencies. From the results, it can be concluded that the actuator acts approximately as a linear system at frequencies up to 1000 Hz. A parametric study is achieved here by applying the developed model to analyze the influence of the geometrical parameters of the fixable hinges on the active and passive actuator properties. The model predictions in the frequency range of 0-1000 Hz show that the hinge thickness, radius, and opening angle parameters have great effects on the frequency dynamic

Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

International Nuclear Information System (INIS)

Liu, X; Lamarque, F; Doré, E; Pouille, P

2015-01-01

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements. (paper)

Multistable wireless micro-actuator based on antagonistic pre-shaped double beams

Science.gov (United States)

Liu, X.; Lamarque, F.; Doré, E.; Pouille, P.

2015-07-01

This paper presents a monolithic multistable micro-actuator based on antagonistic pre-shaped double beams. The designed micro-actuator is formed by two rows of bistable micro-actuators providing four stable positions. The bistable mechanism for each row is a pair of antagonistic pre-shaped beams. This bistable mechanism has an easier pre-load operation compared to the pre-compressed bistable beams method. Furthermore, it solves the asymmetrical force output problem of parallel pre-shaped bistable double beams. At the same time, the geometrical limit is lower than parallel pre-shaped bistable double beams, which ensures a smaller stroke of the micro-actuator with the same dimensions. The designed micro-actuator is fabricated using laser cutting machine on medium density fiberboard (MDF). The bistability and merits of antagonistic pre-shaped double beams are experimentally validated. Finally, a contactless actuation test is performed using 660 nm wavelength laser heating shape memory alloy (SMA) active elements.

Performance evaluation of an improved fish robot actuated by piezoceramic actuators

International Nuclear Information System (INIS)

Nguyen, Q S; Heo, S; Park, H C; Byun, D

2010-01-01

This paper presents an improved fish robot actuated by four lightweight piezocomposite actuators. Our newly developed actuation mechanism is simple to fabricate because it works without gears. With the new actuation mechanism, the fish robot has a 30% smaller cross section than our previous model. Performance tests of the fish robot in water were carried out to measure the tail-beat angle, the thrust force, the swimming speed for various tail-beat frequencies from 1 to 5 Hz and the turning radius at the optimal frequency. The maximum swimming speed of the fish robot is 7.7 cm s −1 at a tail-beat frequency of 3.9 Hz. A turning experiment shows that the swimming direction of the fish robot can be controlled by changing the duty ratio of the driving voltage; the fish robot has a turning radius of 0.41 m for a left turn and 0.68 m for a right turn

Performance evaluation of an improved fish robot actuated by piezoceramic actuators

Science.gov (United States)

Nguyen, Q. S.; Heo, S.; Park, H. C.; Byun, D.

2010-03-01

This paper presents an improved fish robot actuated by four lightweight piezocomposite actuators. Our newly developed actuation mechanism is simple to fabricate because it works without gears. With the new actuation mechanism, the fish robot has a 30% smaller cross section than our previous model. Performance tests of the fish robot in water were carried out to measure the tail-beat angle, the thrust force, the swimming speed for various tail-beat frequencies from 1 to 5 Hz and the turning radius at the optimal frequency. The maximum swimming speed of the fish robot is 7.7 cm s - 1 at a tail-beat frequency of 3.9 Hz. A turning experiment shows that the swimming direction of the fish robot can be controlled by changing the duty ratio of the driving voltage; the fish robot has a turning radius of 0.41 m for a left turn and 0.68 m for a right turn.

A two-degrees-of-freedom miniature manipulator actuated by antagonistic shape memory alloys

International Nuclear Information System (INIS)

Lai, Chih-Ming; Chu, Cheng-Yu; Lan, Chao-Chieh

2013-01-01

This paper presents a miniature manipulator that can provide rotations around two perpendicularly intersecting axes. Each axis is actuated by a pair of shape memory alloy (SMA) wires. SMA wire actuators are known for their large energy density and ease of actuation. These advantages make them ideal for applications that have stringent size and weight constraints. SMA actuators can be temperature-controlled to contract and relax like muscles. When correctly designed, antagonistic SMA actuators have a faster response and larger range of motion than bias-type SMA actuators. This paper proposes an antagonistic actuation model to determine the manipulator parameters that are required to generate sufficient workspace. Effects of SMA prestrain and spring stiffness on the manipulator are investigated. Taking advantage of proper prestrain, the actuator size can be made much smaller while maintaining the same motion. The use of springs in series with SMA can effectively reduce actuator stress. A controller and an anti-slack algorithm are developed to ensure fast and accurate motion. Speed, stress, and loading experiments are conducted to demonstrate the performance of the manipulator. (paper)

Emergency scram actuation device for nuclear reactors

International Nuclear Information System (INIS)

Noyes, R.C.; Zaman, S.U.; Stuteville, D.W.

1979-01-01

The safety parameter employed for emergency scrams of a liquid metal cooled reactor is the coolant pressure. An actuation bellows is provided which is connected to a measuring chamber by means of a flow system. Both units are installed in a coolant flow section. The measuring chamber proper is connected with the coolant by means of an aperture limiting the flow. Inside the measuring chamber there is an expansion space filled with gas. Pressure changes in the coolant affect the pressure in the expansion space. Expansion of the bellows actuates the release mechanism. (DG) [de

Multi-Mode Electric Actuator Dynamic Modelling for Missile Fin Control

Directory of Open Access Journals (Sweden)

Bhimashankar Gurav

2017-06-01

Full Text Available Linear first/second order fin direct current (DC actuator model approximations for missile applications are currently limited to angular position and angular velocity state variables. Furthermore, existing literature with detailed DC motor models is decoupled from the application of interest: tail controller missile lateral acceleration (LATAX performance. This paper aims to integrate a generic DC fin actuator model with dual-mode feedforward and feedback control for tail-controlled missiles in conjunction with the autopilot system design. Moreover, the characteristics of the actuator torque information in relation to the aerodynamic fin loading for given missile trim velocities are also provided. The novelty of this paper is the integration of the missile LATAX autopilot states and actuator states including the motor torque, position and angular velocity. The advantage of such an approach is the parametric analysis and suitability of the fin actuator in relation to the missile lateral acceleration dynamic behaviour.

49 CFR 176.54 - Repairs involving welding, burning, and power-actuated tools and appliances.

Science.gov (United States)

2010-10-01

...-actuated tools and appliances. 176.54 Section 176.54 Transportation Other Regulations Relating to..., burning, and power-actuated tools and appliances. (a) Except as provided in paragraph (b) of this section, repairs or work involving welding or burning, or the use of power-actuated tools or appliances which may...

Magnetic actuators and sensors

CERN Document Server

Brauer, John R

2014-01-01

An accessible, comprehensive guide on magnetic actuators and sensors, this fully updated second edition of Magnetic Actuators and Sensors includes the latest advances, numerous worked calculations, illustrations, and real-life applications. Covering magnetics, actuators, sensors, and systems, with updates of new technologies and techniques, this exemplary learning tool emphasizes computer-aided design techniques, especially magnetic finite element analysis, commonly used by today's engineers. Detailed calculations, numerous illustrations, and discussions of discrepancies make this text an inva

Linear or Rotary Actuator Using Electromagnetic Driven Hammer as Prime Mover

Science.gov (United States)

Paine, Jeffrey S. N. (Inventor); Smith, Byron F. (Inventor); Sesler, Joshua J. (Inventor); Paine, Matthew T. (Inventor); McMahan, Bert K. (Inventor); McMahan, Mark C. (Inventor)

2018-01-01

We claim a hammer driven actuator that uses the fast-motion, low-force characteristics of an electro-magnetic or similar prime mover to develop kinetic energy that can be transformed via a friction interface to produce a higher-force, lower-speed linear or rotary actuator by using a hammering process to produce a series of individual steps. Such a system can be implemented using a voice-coil, electro-mechanical solenoid or similar prime mover. Where a typical actuator provides limited range of motion or low force, the range of motion of a linear or rotary impact driven motor can be configured to provide large displacements which are not limited by the characteristic dimensions of the prime mover.

Lifetime of piezoceramic multilayer actuators : interplay of material properties and actuator design

NARCIS (Netherlands)

Ende, D.A. van den; Bos, B.; Groen, W.A.; Dortmans, L.M.J.G.

2009-01-01

We report an investigation into factors limiting the functional lifetime of multilayer piezoceramic actuators. The study consists of a combination of lifetime experiments by means of an accelerated lifetime test, inspection of the actuator microstructure at different stages of the accelerated

Scissor thrust valve actuator

Science.gov (United States)

DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

2006-08-29

Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

Bistable microelectromechanical actuator

Science.gov (United States)

Fleming, James G.

1999-01-01

A bistable microelectromechanical (MEM) actuator is formed on a substrate and includes a stressed membrane of generally rectangular shape that upon release assumes a curvilinear cross-sectional shape due to attachment at a midpoint to a resilient member and at opposing edges to a pair of elongate supports. The stressed membrane can be electrostatically switched between a pair of mechanical states having mirror-image symmetry, with the MEM actuator remaining in a quiescent state after a programming voltage is removed. The bistable MEM actuator according to various embodiments of the present invention can be used to form a nonvolatile memory element, an optical modulator (with a pair of mirrors supported above the membrane and moving in synchronism as the membrane is switched), a switchable mirror (with a single mirror supported above the membrane at the midpoint thereof) and a latching relay (with a pair of contacts that open and close as the membrane is switched). Arrays of bistable MEM actuators can be formed for applications including nonvolatile memories, optical displays and optical computing.

The application of the detection filter to aircraft control surface and actuator failure detection and isolation

Science.gov (United States)

Bonnice, W. F.; Wagner, E.; Motyka, P.; Hall, S. R.

1985-01-01

The performance of the detection filter in detecting and isolating aircraft control surface and actuator failures is evaluated. The basic detection filter theory assumption of no direct input-output coupling is violated in this application due to the use of acceleration measurements for detecting and isolating failures. With this coupling, residuals produced by control surface failures may only be constrained to a known plane rather than to a single direction. A detection filter design with such planar failure signatures is presented, with the design issues briefly addressed. In addition, a modification to constrain the residual to a single known direction even with direct input-output coupling is also presented. Both the detection filter and the modification are tested using a nonlinear aircraft simulation. While no thresholds were selected, both filters demonstrated an ability to detect control surface and actuator failures. Failure isolation may be a problem if there are several control surfaces which produce similar effects on the aircraft. In addition, the detection filter was sensitive to wind turbulence and modeling errors.

Design and demonstration of a fish robot actuated by a SMA-driven actuation system

Science.gov (United States)

Le, Chan H.; Nguyen, Quang S.; Park, Hoon C.

2010-04-01

This paper presents a concept of a fish robot actuated by an SMA-based actuator. The bending-type actuator system is composed of a 0.1mm diameter SMA wire and a 0.5mm thick glass/epoxy strip. The SMA wire is installed to the bent composite strip. The actuator can produce about 200gf of blocking force and 3.5mm displacement at the center of the glass/epoxy strip. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed and thrust produced by the fish robot. The tail-beat angle is about 20° and the maximum swimming speed is about 1.6cm/s. The measured thrust is about 0.4gf when the fish robot is operated at 0.9Hz.

Qualification of safety-related valve actuators

International Nuclear Information System (INIS)

Anon.

1981-01-01

This Standard describes the qualification of all types of power-driven valve actuators, including damper actuators, for safety-related functions in nuclear power generating stations. It may also be used to separately qualify actuator components. This Standard establishes the minimum requirements for, and guidance regarding, the methods and procedures for qualification of all safety-related functions of power-driven valve actuators

Robust adaptive multivariable higher-order sliding mode flight control for air-breathing hypersonic vehicle with actuator failures

Directory of Open Access Journals (Sweden)

Peng Li

2016-10-01

Full Text Available This article proposes an adaptive multivariable higher-order sliding mode control for the longitudinal model of an air-breathing vehicle under system uncertainties and actuator failures. Firstly, a fast finite-time control law is designed for a chain of integrators. Secondly, based on the input/output feedback linearization technique, the system uncertainty and external disturbances are modeled as additive certainty and the actuator failures are modeled as multiplicative uncertainty. By using the proposed fast finite-time control law, a robust multivariable higher-order sliding mode control is designed for the air-breathing hypersonic vehicle with actuator failures. Finally, adaptive laws are proposed for the adaptation of the parameters in the robust multivariable higher-order sliding mode control. Thus, the bounds of the uncertainties are not needed in the control system design. Simulation results show the effectiveness of the proposed robust adaptive multivariable higher-order sliding mode control.

Control of a flexible beam actuated by macro-fiber composite patches: II. Hysteresis and creep compensation, experimental results

International Nuclear Information System (INIS)

Schröck, Johannes; Meurer, Thomas; Kugi, Andreas

2011-01-01

This paper considers a flexible cantilever beam, which is actuated by piezoelectric macro-fiber composite (MFC) patch actuators. For accurate positioning tasks, special attention has to be paid to the inherent nonlinear hysteresis and creep behavior of these actuators. A detailed analysis of the MFC-actuated cantilever verifies that these nonlinearities can be efficiently captured by an operator-based model using Prandtl–Ishlinskii's theory. Based on a Hammerstein-like model with the nonlinearities at the input connected in series with a linear infinite-dimensional beam model it follows that hysteresis and creep effects can be compensated by application of the inverse operator. Experimental results prove the feasibility of this approach. With this result, the tracking accuracy of the combination of the compensator with the flatness-based feedforward control design as proposed in the companion paper (Schröck et al 2011 Smart Mater. Struct. 20 015015) can be verified. Measurements demonstrate the applicability of this approach for the realization of highly dynamic trajectories for the beam's tip deflection

Dynamic Pull-In Investigation of a Clamped-Clamped Nanoelectromechanical Beam under Ramp-Input Voltage and the Casimir Force

Directory of Open Access Journals (Sweden)

Amir R. Askari

2014-01-01

Full Text Available The influence of the Casimir excitation on dynamic pull-in instability of a nanoelectromechanical beam under ramp-input voltage is studied. The ramp-input actuation has applications in frequency sweeping of RF-N/MEMS. The presented model is nonlinear due to the inherent nonlinearity of electrostatics and the Casimir excitations as well as the geometric nonlinearity of midplane stretching. A Galerkin based reduced order modeling is utilized. It is found that the calculated dynamic pull-in ramp input voltage leads to dynamic pull-in step input voltage by increasing the slope of voltage-time diagram. This fact is utilized to verify the results of present study.

Modelling and characterization of inflated dielectric elastomer actuators with tubular configuration

International Nuclear Information System (INIS)

Zhang, Chi; Chen, Hualing; Liu, Lei; Li, Dichen

2015-01-01

A dielectric elastomer undergoes large and fast deformation subject to external electric stimuli, making it a promising artificial muscle for various kinds of actuators, sensors and energy generators. This paper presents an actuator fabricated by (1) rolling a dielectric elastomer membrane, (2) pre-stretching the membrane along the radial direction and fixing the edges with rigid cylindrical plastic ends, and (3) applying a force to the end along the longitudinal direction and pumping air into the tube for inflation. Subject to a voltage, the structure works as an actuator with a large linear stroke. Governing equations of this actuator are established and simulation results are found to agree well with experimental results. We examine four modes of failure, namely loss of tension, electrical breakdown, snap-through instability and tensile rupture, with a variation in applied pressure. The actuating voltage is greatly reduced by applying pressure, providing the possibility of low-voltage driving. By regulating the applied pressure, large actuation strain and displacement are obtained simultaneously and the distributions of stretch, true stress and the true electric field become more homogeneous. (paper)

Spacecraft Hybrid (Mixed-Actuator) Attitude Control Experiences on NASA Science Missions

Science.gov (United States)

Dennehy, Cornelius J.

2014-01-01

There is a heightened interest within NASA for the design, development, and flight implementation of mixed-actuator hybrid attitude control systems for science spacecraft that have less than three functional reaction wheel actuators. This interest is driven by a number of recent reaction wheel failures on aging, but what could be still scientifically productive, NASA spacecraft if a successful hybrid attitude control mode can be implemented. Over the years, hybrid (mixed-actuator) control has been employed for contingency attitude control purposes on several NASA science mission spacecraft. This paper provides a historical perspective of NASA's previous engineering work on spacecraft mixed-actuator hybrid control approaches. An update of the current situation will also be provided emphasizing why NASA is now so interested in hybrid control. The results of the NASA Spacecraft Hybrid Attitude Control Workshop, held in April of 2013, will be highlighted. In particular, the lessons learned captured from that workshop will be shared in this paper. An update on the most recent experiences with hybrid control on the Kepler spacecraft will also be provided. This paper will close with some future considerations for hybrid spacecraft control.

Soft Somatosensitive Actuators via Embedded 3D Printing.

Science.gov (United States)

Truby, Ryan L; Wehner, Michael; Grosskopf, Abigail K; Vogt, Daniel M; Uzel, Sebastien G M; Wood, Robert J; Lewis, Jennifer A

2018-04-01

Humans possess manual dexterity, motor skills, and other physical abilities that rely on feedback provided by the somatosensory system. Herein, a method is reported for creating soft somatosensitive actuators (SSAs) via embedded 3D printing, which are innervated with multiple conductive features that simultaneously enable haptic, proprioceptive, and thermoceptive sensing. This novel manufacturing approach enables the seamless integration of multiple ionically conductive and fluidic features within elastomeric matrices to produce SSAs with the desired bioinspired sensing and actuation capabilities. Each printed sensor is composed of an ionically conductive gel that exhibits both long-term stability and hysteresis-free performance. As an exemplar, multiple SSAs are combined into a soft robotic gripper that provides proprioceptive and haptic feedback via embedded curvature, inflation, and contact sensors, including deep and fine touch contact sensors. The multimaterial manufacturing platform enables complex sensing motifs to be easily integrated into soft actuating systems, which is a necessary step toward closed-loop feedback control of soft robots, machines, and haptic devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biomimetic photo-actuation: sensing, control and actuation in sun-tracking plants

International Nuclear Information System (INIS)

Dicker, M P M; Bond, I P; Weaver, P M; Rossiter, J M

2014-01-01

Although the actuation mechanisms that drive plant movement have been investigated from a biomimetic perspective, few studies have looked at the wider sensing and control systems that regulate this motion. This paper examines photo-actuation—actuation induced by, and controlled with light—through a review of the sun-tracking functions of the Cornish Mallow. The sun-tracking movement of the Cornish Mallow leaf results from an extraordinarily complex—yet extremely elegant—process of signal perception, generation, filtering and control. Inspired by this process, a concept for a simplified biomimetic analogue of this leaf is proposed: a multifunctional structure employing chemical sensing, signal transmission, and control of composite hydrogel actuators. We present this multifunctional structure, and show that the success of the concept will require improved selection of materials and structural design. This device has application in the solar-tracking of photovoltaic panels for increased energy yield. More broadly it is envisaged that the concept of chemical sensing and control can be expanded beyond photo-actuation to many other stimuli, resulting in new classes of robust solid-state devices. (paper)

Decentralized coverage control problems for mobile robotic sensor and actuator networks

CERN Document Server

Savkin, A; Xi, Z; Javed, F; Matveev, A; Nguyen, H

2015-01-01

This book introduces various coverage control problems for mobile sensor networks including barrier, sweep and blanket. Unlike many existing algorithms, all of the robotic sensor and actuator motion algorithms developed in the book are fully decentralized or distributed, computationally efficient, easily implementable in engineering practice and based only on information on the closest neighbours of each mobile sensor and actuator and local information about the environment. Moreover, the mobile robotic sensors have no prior information about the environment in which they operation. These various types of coverage problems have never been covered before by a single book in a systematic way. Another topic of this book is the study of mobile robotic sensor and actuator networks. Many modern engineering applications include the use of sensor and actuator networks to provide efficient and effective monitoring and control of industrial and environmental processes. Such mobile sensor and actuator networks are abl...

Slit Tubes for Semisoft Pneumatic Actuators.

Science.gov (United States)

Belding, Lee; Baytekin, Bilge; Baytekin, Hasan Tarik; Rothemund, Philipp; Verma, Mohit S; Nemiroski, Alex; Sameoto, Dan; Grzybowski, Bartosz A; Whitesides, George M

2018-03-01

This article describes a new principle for designing soft or 'semisoft' pneumatic actuators: SLiT (for SLit-in-Tube) actuators. Inflating an elastomeric balloon, when enclosed by an external shell (a material with higher Young's modulus) containing slits of different directions and lengths, produces a variety of motions, including bending, twisting, contraction, and elongation. The requisite pressure for actuation depends on the length of the slits, and this dependence allows sequential actuation by controlling the applied pressure. Different actuators can also be controlled using external "sliders" that act as reprogrammable "on-off" switches. A pneumatic arm and a walker constructed from SLiT actuators demonstrate their ease of fabrication and the range of motions they can achieve. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Analysis of the sweeped actuator line method

OpenAIRE

Nathan Jörn; Masson Christian; Dufresne Louis; Churchfield Matthew

2015-01-01

The actuator line method made it possible to describe the near wake of a wind turbine more accurately than with the actuator disk method. Whereas the actuator line generates the helicoidal vortex system shed from the tip blades, the actuator disk method sheds a vortex sheet from the edge of the rotor plane. But with the actuator line come also temporal and spatial constraints, such as the need for a much smaller time step than with actuator disk. While the latter one only has to obey the Cour...

Plasma actuators for bluff body flow control

Science.gov (United States)

Kozlov, Alexey V.

The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

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

Directory of Open Access Journals (Sweden)

Jeremy Krause

2018-05-01

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

Development of an air-operated actuator performance monitoring system for regulatory usage

International Nuclear Information System (INIS)

Sung, K. Y.; Kwon, S. J.

2004-01-01

The performance monitoring system of air-operated actuators for regulatory usage has been being developed. Essential elements and operating parameters affecting the actuator performance have been investigated to provide basic information for system development. The monitoring system including an air-operated actuator testing facility and analysis softwares for monitoring and evaluation are also introduced in this paper. As a result of simulated tests, it was known that the system could be a useful tool for the effective monitoring of actuator performance change and fault conditions. This system would be applied to regulatory inspection for utility's data validation and to the training of regulatory staff in future after some modification and expansion

Structural Integration of Sensors/Actuators by Laser Beam Melting for Tailored Smart Components

Science.gov (United States)

Töppel, Thomas; Lausch, Holger; Brand, Michael; Hensel, Eric; Arnold, Michael; Rotsch, Christian

2018-03-01

Laser beam melting (LBM), an additive laser powder bed fusion technology, enables the structural integration of temperature-sensitive sensors and actuators in complex monolithic metallic structures. The objective is to embed a functional component inside a metal part without losing its functionality by overheating. The first part of this paper addresses the development of a new process chain for bonded embedding of temperature-sensitive sensor/actuator systems by LBM. These systems are modularly built and coated by a multi-material/multi-layer thermal protection system of ceramic and metallic compounds. The characteristic of low global heat input in LBM is utilized for the functional embedding. In the second part, the specific functional design and optimization for tailored smart components with embedded functionalities are addressed. Numerical and experimental validated results are demonstrated on a smart femoral hip stem.

Micro-mechanics of ionic electroactive polymer actuators

Science.gov (United States)

Punning, Andres; Põldsalu, Inga; Kaasik, Friedrich; Vunder, Veiko; Aabloo, Alvo

2015-04-01

Commonly, modeling of the bending behavior of the ionic electroactive polymer (IEAP) actuators is based on the classical mechanics of cantilever beam. It is acknowledged, that the actuation of the ionic electroactive polymer (IEAP) actuators is symmetric about the centroid - the convex side of the actuator is expanding and the concave side is contracting for exactly the same amount, while the thickness of the actuator remains invariant. Actuating the IEAP actuators and sensors under scanning electron microscope (SEM), in situ, reveals that for some types of them this approach is incorrect. Comparison of the SEM micrographs using the Digital Image Correction (DIC) method results with the precise strain distribution of the IEAP actuators in two directions: in the axial direction, and in the direction of thickness. This information, in turn, points to the physical processes taking place within the electrodes as well as membrane of the trilayer laminate of sub-millimeter thickness. Comparison of the EAP materials, engaged as an actuator as well as a sensor, reveals considerable differences between the micro-mechanics of the two modes.

Experimental characterization of the hysteretic and rate-dependent electromechanical behavior of dielectric electro-active polymer actuators

International Nuclear Information System (INIS)

York, A; Seelecke, S; Dunn, J

2010-01-01

Dielectric electro-active polymers (DEAPs) can achieve substantial deformation (>300% strain) while sustaining, compared to their ionic counterparts, large forces. This makes them attractive for various actuation and sensing applications such as in light weight and energy efficient valve and pumping systems. Many applications operate DEAP actuators at higher frequencies where rate-dependent effects influence their performance. This motivates the seeking of dynamic characterization of these actuators beyond the quasi-static regime. This paper provides a systematic experimental investigation of the quasi-static and dynamic electromechanical properties of a DEAP actuator. In order to completely characterize the fully coupled behavior, force versus displacement measurements at various constant voltages and force versus voltage measurements at various fixed displacements are conducted. The experiments are conducted with a particular focus on the hysteretic and rate-dependent material behavior. These experiments provide insight into the electrical dynamics and viscoelastic relaxation inherent in DEAP actuators. This study is intended to provide information, including high frequency performance analysis, useful to anyone designing dynamic actuator systems using DEAPs

Application of a permanent magnet biased E-Core reluctance actuator in a magnetically suspended ceiling actuator

NARCIS (Netherlands)

Overboom, T.T.; Jansen, J.W.; Lomonova, E.

2010-01-01

In the paper a novel actuator is presented for a magnetically suspended ceiling actuator. The actuator consists of several stator segments which contain the coils and the magnets. The armature, therefore, has a totally passive design. Because of its salient structure, a translational force can be

Development of an all-metal electrothermal actuator and its applications

Science.gov (United States)

Luo, JiKui; He, Johnny H.; Flewitt, Andrew J.; Moore, David F.; Spearing, S. Mark; Fleck, Norman A.; Milne, Williams I.

2004-01-01

The in-plane motion of microelectrothermal actuator ("heatuator") has been analysed for Si-based and metallic devices. It was found that the lateral deflection of a heatuator made of a Ni-metal is about ~60% larger than that of a Si-based actuator under the same power consumption. Metals are much better for thermal actuators as they provide a relatively large deflection and large force, for a low operating temperature, and power consumption. Electroplated Ni films were used to fabricate heatuators. The electrical and mechanical properties of electroplated Ni thin films have been investigated as a function of temperature and plating current density, and the process conditions have been optimised to obtain stress-free films suitable for MEMS applications. Lateral thermal actuators have been successfully fabricated, and electrically tested. Microswitches and microtweezers utilising the heatuator have also been fabricated and tested.

High-displacement spiral piezoelectric actuators

Science.gov (United States)

Mohammadi, F.; Kholkin, A. L.; Jadidian, B.; Safari, A.

1999-10-01

A high-displacement piezoelectric actuator, employing spiral geometry of a curved piezoelectric strip is described. The monolithic actuators are fabricated using a layered manufacturing technique, fused deposition of ceramics, which is capable of prototyping electroceramic components with complex shapes. The spiral actuators (2-3 cm in diameter) consisted of 4-5 turns of a lead zirconate titanate ceramic strip with an effective length up to 28 cm. The width was varied from 0.9 to 1.75 mm with a height of 3 mm. When driven by the electric field applied across the width of the spiral wall, the tip of the actuator was found to displace in both radial and tangential directions. The tangential displacement of the tip was about 210 μm under the field of 5 kV/cm. Both the displacement and resonant frequency of the spirals could be tailored by changing the effective length and wall width. The blocking force of the actuator in tangential direction was about 1 N under the field of 5 kV/cm. These properties are advantageous for high-displacement low-force applications where bimorph or monomorph actuators are currently employed.

Nature-inspired microfluidic manipulation using magnetic actuators

NARCIS (Netherlands)

Khaderi, S. N.; Ioan, D.; den Toonder, J.M.J.; Onck, P. R.; LaVan, D.; Spearing, M.; Vengallatore, S.; DaSilva, M.

2008-01-01

Magnetically actuated micro-actuators are proposed to propel and manipulate fluid in micro-channels. As the fluid flows at low Reynolds number in such systems, the actuator should move in an asymmetric manner. The proposed actuators are polymer films with embedded magnetic particles, which are

A Vehicular Guidance Wireless Sensor/Actuator Network

KAUST Repository

Boudellioua, Imene

2012-07-01

Sensor networks have been heralded as one of 21 most important technologies for the 21st century by Business Week [1]. Wireless sensor/actuator networks (WSANs)are emerging as a new generation of sensor networks with the potential for enhancing the versatility and effectiveness of sensor networks. However, the unreliability of wireless communications and the real-time requirements of control applications raise great challenges for WSAN design. In this thesis, we design a WSAN for a vehicular guidance system targeting environmental disaster management applications. In this system, actuators provide mobility to all sensor nodes in the observed area whenever needed. Moreover, nodes form clusters and their movement is controlled by a master node that is selected dynamically. We also discuss the factors affecting our network performance in real-life and propose a framework which accounts for real-time requirement and reliable actuation. We finally perform some experimental studies on our system to measure its performance in an indoor environment.

A Portable, Air-Jet-Actuator-Based Device for System Identification

Science.gov (United States)

Staats, Wayne; Belden, Jesse; Mazumdar, Anirban; Hunter, Ian

2010-11-01

System identification (ID) of human and robotic limbs could help in diagnosis of ailments and aid in optimization of control parameters and future redesigns. We present a self-contained actuator, which uses the Coanda effect to rapidly switch the direction of a high speed air jet to create a binary stochastic force input to a limb for system ID. The design of the actuator is approached with the goal of creating a portable device, which could deployed on robot or human limbs for in situ identification. The viability of the device is demonstrated by performing stochastic system ID on an underdamped elastic beam system with fixed inertia and stiffness, and variable damping. The non-parametric impulse response yielded from the stochastic system ID is modeled as a second order system, and the resultant parameters are found to be in excellent agreement with those found using more traditional system ID techniques. The current design could be further miniaturized and developed as a portable, wireless, on-site multi-axis system identification system for less intrusive and more widespread use.

Actuation of atomic force microscopy microcantilevers using contact acoustic nonlinearities

Energy Technology Data Exchange (ETDEWEB)

Torello, D.; Degertekin, F. Levent, E-mail: levent.degertekin@me.gatech.edu [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States)

2013-11-15

A new method of actuating atomic force microscopy (AFM) cantilevers is proposed in which a high frequency (>5 MHz) wave modulated by a lower frequency (∼300 kHz) wave passes through a contact acoustic nonlinearity at the contact interface between the actuator and the cantilever chip. The nonlinearity converts the high frequency, modulated signal to a low frequency drive signal suitable for actuation of tapping-mode AFM probes. The higher harmonic content of this signal is filtered out mechanically by the cantilever transfer function, providing for clean output. A custom probe holder was designed and constructed using rapid prototyping technologies and off-the-shelf components and was interfaced with an Asylum Research MFP-3D AFM, which was then used to evaluate the performance characteristics with respect to standard hardware and linear actuation techniques. Using a carrier frequency of 14.19 MHz, it was observed that the cantilever output was cleaner with this actuation technique and added no significant noise to the system. This setup, without any optimization, was determined to have an actuation bandwidth on the order of 10 MHz, suitable for high speed imaging applications. Using this method, an image was taken that demonstrates the viability of the technique and is compared favorably to images taken with a standard AFM setup.

Use of microinterrupts to provide an instrument oriented input/output structure

International Nuclear Information System (INIS)

Zaky, S.G.

1981-01-01

This paper describes the design of a bit-slice based computer, which has been developed for use in data acquisition and control applications. The main design goals have been to provide fast response to external events, and sufficient processing capability to perform data reduction in real time. The initial application of this computer has been in airborne, geophysical surveying, where such instruments as Gamma-ray spectrometers, magnetometers and navigation equipment are involved. In order to meet the response requirement mentioned above, a microinterrupt facility has been incorporated. Microinterrupts are serviced in microcodes routines which can be initiated within a maximum of two microinstruction cycle times from an external event. This facility makes it possible to implement powerful input/output control functions without the need for complex and specialized hardware interfaces for each instrument. (orig.)

Hysteresis modeling and identification of a dielectric electro-active polymer actuator using an APSO-based nonlinear Preisach NARX fuzzy model

International Nuclear Information System (INIS)

Truong, Bui Ngoc Minh; Nam, Doan Ngoc Chi; Ahn, Kyoung Kwan

2013-01-01

Dielectric electro-active polymer (DEAP) materials are attractive since they are low cost, lightweight and have a large deformation capability. They have no operating noise, very low electric power consumption and higher performance and efficiency than competing technologies. However, DEAP materials generally have strong hysteresis as well as uncertain and nonlinear characteristics. These disadvantages can limit the efficiency in the use of DEAP materials. To address these limitations, this research will present the combination of the Preisach model and the dynamic nonlinear autoregressive exogenous (NARX) fuzzy model-based adaptive particle swarm optimization (APSO) identification algorithm for modeling and identification of the nonlinear behavior of one typical type of DEAP actuator. Firstly, open loop input signals are applied to obtain nonlinear features and to investigate the responses of the DEAP actuator system. Then, a Preisach model can be combined with a dynamic NARX fuzzy structure to estimate the tip displacement of a DEAP actuator. To optimize all unknown parameters of the designed combination, an identification scheme based on a least squares method and an APSO algorithm is carried out. Finally, experimental validation research is carefully completed, and the effectiveness of the proposed model is evaluated by employing various input signals. (paper)

MDEP Common Position CP-DICWG-13. Common position on spurious actuation

International Nuclear Information System (INIS)

2017-01-01

Spurious actuations produced by Instrumentation and Control (I and C) systems are a safety concern if such actuations could challenge plant safety. Spurious actuations can lead to unnecessary challenges to safety equipment, challenge the ability of safety systems to provide their intended functions, or place the plant in an un-analysed state. Spurious actuation of plant equipment can be caused by factors including, but not limited to, single failures, common cause failures, human (e.g. operator) action, maintenance errors, design errors, or missing requirements. Modern I and C systems can have inter-connectivities, dependencies and commonalities that can, if the overall I and C architecture and the individual I and C systems are not adequately developed and operated, facilitate fault propagation, leading to potential spurious actuation of one or more trains of plant equipment. Sources and contributors of spurious actuations of multiple trains of plant equipment may include inadequate independence among redundant portions of I and C systems, inappropriate allocation of I and C functions, inadequate qualification or design of supporting systems (e.g. heating, ventilation and air conditioning (HVAC) system), or non-classified systems that could have been erroneously classified. Spurious actuations are a type of hazard. Generic Common Position (GCP) DICWG-10 'Common Position on Hazard Identification and Controls for Digital Instrumentation and Control Systems' provides a set of common positions pertaining to identifying and controlling hazards in an I and C system. This common position was developed to add special considerations when identifying and controlling hazards that include spurious actuations. It is expected that GCP DICWG-10 and the common positions in this document be used together for a complete analysis of hazards and their controls (e.g. prevention of spurious actuations in the design of the system/component). Spurious actuations of concern

Unidirectional variable stiffness hydraulic actuator for load-carrying knee exoskeleton

Directory of Open Access Journals (Sweden)

Jun Zhu

2017-01-01

Full Text Available This article presents the design and experimental testing of a unidirectional variable stiffness hydraulic actuator for load-carrying knee exoskeleton. The proposed actuator is designed for mimicking the high-efficiency passive behavior of biological knee and providing actively assistance in locomotion. The adjustable passive compliance of exoskeletal knee is achieved through a variable ratio lever mechanism with linear elastic element. A compact customized electrohydraulic system is also designed to accommodate application demands. Preliminary experimental results show the prototype has good performances in terms of stiffness regulation and joint torque control. The actuator is also implemented in an exoskeleton knee joint, resulting in anticipant human-like passive compliance behavior.

Modeling of electro-statically actuated two-axis (tip-tilt) MEMS torsion micro-mirrors for laser beamsteering

Science.gov (United States)

Edwards, C. L.; Boone, B. G.; Levine, W. S.; Davis, C. C.

2007-04-01

The availability of recently developed MEMS micro-mirror technology provides an opportunity to replace macro-scale actuators for free-space laser beamsteering in lidar and communication systems. Such an approach is under investigation at the Johns Hopkins University Applied Physics Laboratory for use on space-based platforms. Precision modeling of mirror pointing and its dynamics are critical to optimal design and control of MEMS beamsteerers. Beginning with Hornbeck's torque approach, this paper presents a first-principle, analytically closed-form torque model for an electro-statically actuated two-axis (tip-tilt) MEMS structure. An Euler dynamic equation formulation describes the gimbaled motion as a coupled pair of damped harmonic oscillators with a common forcing function. Static physical parameters such as MEMS mirror dimensions, facet mass, and height are inputs to the model as well as dynamic harmonic oscillator parameters such as damping and restoring constants fitted from measurements. A Taylor series expansion of the torque function provides valuable insights into basic one dimensional as well as two dimensional MEMS behavior, including operational sensitivities near "pull-in." The model also permits the natural inclusion and analysis of pointing noise sources such as electrical drive noise, platform vibration, and molecular Brownian motion. MATLAB and SIMULINK simulations illustrate performance sensitivities, controllability, and physical limitations, important considerations in the design of optimal pointing systems.

Haptic control of a pneumatic muscle actuator to provide resistance for simulated isokinetic exercise; part II: control development and testing.

Science.gov (United States)

Hall, Kara L; Phillips, Chandler A; Reynolds, David B; Mohler, Stanley R; Rogers, Dana B; Neidhard-Doll, Amy T

2015-01-01

Pneumatic muscle actuators (PMAs) have a high power to weight ratio and possess unique characteristics which make them ideal actuators for applications involving human interaction. PMAs are difficult to control due to nonlinear dynamics, presenting challenges in system implementation. Despite these challenges, PMAs have great potential as a source of resistance for strength training and rehabilitation. The objective of this work was to control a PMA for use in isokinetic exercise, potentially benefiting anyone in need of optimal strength training through a joint's range of motion. The controller, based on an inverse three-element phenomenological model and adaptive nonlinear control, allows the system to operate as a type of haptic device. A human quadriceps dynamic simulator was developed (as described in Part I of this work) so that control effectiveness and accommodation could be tested prior to human implementation. Tracking error results indicate that the control system is effective at producing PMA displacement and resistance necessary for a scaled, simulated neuromuscular actuator to maintain low-velocity isokinetic movement during simulated concentric and eccentric knee extension.

Modeling and Investigation of Electromechanical Valve Train Actuator at simulated Pressure conditions

DEFF Research Database (Denmark)

Habib, Tufail

2012-01-01

In an electromechanical valve actuated engine, the valves are driven by solenoid-type actuators and cam-shaft is eliminated. Control of each valve provides flexibility in valve timings over all engine conditions and achieves the benefits of variable valve timing(VVT). This paper is about investig...

Design and control of hybrid actuation lower limb exoskeleton

Directory of Open Access Journals (Sweden)

Hipolito Aguilar-Sierra

2015-06-01

Full Text Available In this article, two types of actuators are applied for a lower limb exoskeleton. They are DC motors with the harmonic drive and the pneumatic artificial muscles. This combination takes advantages of both the harmonic drive and the pneumatic artificial muscle. It provides both high accuracy position control and high ratio of strength and weight. The shortcomings of the two actuators are overcome by the hybrid actuation, for example, low control accuracy and modeling difficult of pneumatic artificial muscle, compactness, and structural flexibility of DC motors. The design and modeling processes are discussed to show the proposed exoskeleton can increase the strength of human lower limbs. Experiments and analysis of the exoskeleton are given to evaluate the effectiveness of the design and modeling.

Artificial heart for humanoid robot using coiled SMA actuators

Science.gov (United States)

Potnuru, Akshay; Tadesse, Yonas

2015-03-01

Previously, we have presented the design and characterization of artificial heart using cylindrical shape memory alloy (SMA) actuators for humanoids [1]. The robotic heart was primarily designed to pump a blood-like fluid to parts of the robot such as the face to simulate blushing or anger by the use of elastomeric substrates for the transport of fluids. It can also be used for other applications. In this paper, we present an improved design by using high strain coiled SMAs and a novel pumping mechanism that uses sequential actuation to create peristalsis-like motions, and hence pump the fluid. Various placements of actuators will be investigated with respect to the silicone elastomeric body. This new approach provides a better performance in terms of the fluid volume pumped.

Frequency-dependent electrostatic actuation in microfluidic MEMS.

Energy Technology Data Exchange (ETDEWEB)

Zavadil, Kevin Robert; Michalske, Terry A.; Sounart, Thomas L.

2003-09-01

Electrostatic actuators exhibit fast response times and are easily integrated into microsystems because they can be fabricated with standard IC micromachining processes and materials. Although electrostatic actuators have been used extensively in 'dry' MEMS, they have received less attention in microfluidic systems probably because of challenges such as electrolysis, anodization, and electrode polarization. Here we demonstrate that ac drive signals can be used to prevent electrode polarization, and thus enable electrostatic actuation in many liquids, at potentials low enough to avoid electrochemistry. We measure the frequency response of an interdigitated silicon comb-drive actuator in liquids spanning a decade of dielectric permittivities and four decades of conductivity, and present a simple theory that predicts the characteristic actuation frequency. The analysis demonstrates the importance of the native oxide on silicon actuator response, and suggests that the actuation frequency can be shifted by controlling the thickness of the oxide. For native silicon devices, actuation is predicted at frequencies less than 10 MHz, in electrolytes of ionic strength up to 100 mmol/L, and thus electrostatic actuation may be feasible in many bioMEMS and other microfluidic applications.

Design and control of electromagnetic clutch actuation system for automated manual transmission

Science.gov (United States)

Ranjan, Ashish; Prasanth, S.; Cherian, Fenin; Baskar, P.

2017-11-01

There is a growing interest towards Automatic Transmission in India as it provides better comfort and drivability. But the high cost of this system is limiting itself to be successful in the Indian markets. Due to this, Automated Manual Transmission (AMT) is considered which provides a better solution towards automation as it enhances the drivability and fuel consumption characteristics of a manual transmission at lower costs. However, torque lag and comfort are major issues with AMT which can be addressed by reducing the shift time. In this paper we describe an Electromagnetic Linear Clutch Actuator as a replacement to current electrohydraulic and electromechanical actuator. A control system for the actuator is presented and a clutch engagement strategy is also implemented which reduces the engagement time to 0.78 seconds while reducing jerk and torque lag. The actuator and control system is simulated on a MATLAB Simulink and agreeable results have been obtained.

Graphene-nanoplatelet-based photomechanical actuators

International Nuclear Information System (INIS)

Loomis, James; King, Ben; Burkhead, Tom; Xu Peng; Bessler, Nathan; Panchapakesan, Balaji; Terentjev, Eugene

2012-01-01

This paper reports large light-induced reversible and elastic responses of graphene nanoplatelet (GNP) polymer composites. Homogeneous mixtures of GNP/polydimethylsiloxane (PDMS) composites (0.1–5 wt%) were prepared and their infrared (IR) mechanical responses studied with increasing pre-strains. Using IR illumination, a photomechanically induced change in stress of four orders of magnitude as compared to pristine PDMS polymer was measured. The actuation responses of the graphene polymer composites depended on the applied pre-strains. At low levels of pre-strain (3–9%) the actuators showed reversible expansion while at high levels (15–40%) the actuators exhibited reversible contraction. The GNP/PDMS composites exhibited higher actuation stresses compared to other forms of nanostructured carbon/PDMS composites, including carbon nanotubes (CNTs), for the same fabrication method. An extraordinary optical-to-mechanical energy conversion factor (η M ) of 7–9 MPa W −1 for GNP-based polymer composite actuators is reported. (paper)

Piezoelectric Actuator/Sensor Technology at Rockwell

Science.gov (United States)

Neurgaonkar, Ratnakar R.

1996-01-01

We describe the state-of-the art of piezoelectric materials based on perovskite and tungsten bronze families for sensor, actuator and smart structure applications. The microstructural defects in these materials have been eliminated to a large extent and the resulting materials exhibit exceedingly high performance for various applications. The performance of Rockwell actuators/sensors is at least 3 times better than commercially available products. These high performance actuators are being incorporated into various applications including, DOD, NASA and commercial. The multilayer actuator stacks fabricated from our piezoceramics are advantageous for sensing and high capacitance applications. In this presentation, we will describe the use of our high performance piezo-ceramics for actuators and sensors, including multilayer stacks and composite structures.

Nanostructured carbon materials based electrothermal air pump actuators

Science.gov (United States)

Liu, Qing; Liu, Luqi; Kuang, Jun; Dai, Zhaohe; Han, Jinhua; Zhang, Zhong

2014-05-01

Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid films as heating elements to transfer electrical stimulus into thermal energy, and finally convert it into mechanical energy. Both the actuation displacement and working temperature of the actuator films show the monotonically increasing trend with increasing driving voltage within the actuation process. Compared with common polymer nanocomposites based electrothermal actuators, our actuators exhibited better actuation performances with a low driving voltage (film actuator due to the intrinsic gas-impermeability nature of graphene platelets. In addition, the high modulus of the r-GO and GO/SWCNT films also guaranteed the large generated stress and high work density. Specifically, the generated stress and gravimetric work density of the GO/SWCNT hybrid film actuator could reach up to more than 50 MPa and 30 J kg-1, respectively, under a driving voltage of 10 V. The resulting stress value is at least two orders of magnitude higher than that of natural muscles (~0.4 MPa).Actuator materials can directly convert different types of energy into mechanical energy. In this work, we designed and fabricated electrothermal air pump-type actuators by utilization of various nanostructured carbon materials, including single wall carbon nanotubes (SWCNTs), reduced graphene oxide (r-GO), and graphene oxide (GO)/SWCNT hybrid films as heating elements to transfer electrical stimulus into thermal energy, and finally convert it into mechanical energy. Both the actuation displacement and working temperature of the actuator films show the monotonically increasing trend with increasing driving voltage within the actuation process. Compared with

Two-stage actuation system using DC motors and piezoelectric actuators for controllable industrial and automotive brakes and clutches

Science.gov (United States)

Neelakantan, Vijay A.; Washington, Gregory N.; Bucknor, Norman K.

2005-05-01

High bandwidth actuation systems that are capable of simultaneously producing relatively large forces and displacements are required for use in automobiles and other industrial applications. Conventional hydraulic actuation mechanisms used in automotive brakes and clutches are complex, inefficient and have poor control robustness. These lead to reduced fuel economy, controllability issues and other disadvantages. This paper involves the design, development, testing and control of a two-stage hybrid actuation mechanism by combining classical actuators like DC motors and advanced smart material actuators like piezoelectric actuators. The paper also discusses the development of a robust control methodology using the Internal Model Control (IMC) principle and emphasizes the robustness property of this control methodology by comparing and studying simulation and experimental results.

Memory characteristics of hysteresis and creep in multi-layer piezoelectric actuators: An experimental analysis

Energy Technology Data Exchange (ETDEWEB)

Biggio, Matteo [Department of Electrical, Electronic, Telecommunications Engineering and Naval Architecture, University of Genoa, Via Opera Pia 11a, Genova (Italy); Butcher, Mark [Engineering Department, CERN (Switzerland); Giustiniani, Alessandro; Masi, Alessandro [Engineering Department, CERN (Switzerland); Department of Engineering, University of Sannio, Piazza Roma, 21, I-82100 Benevento (Italy); Storace, Marco, E-mail: marco.storace@unige.it [Department of Electrical, Electronic, Telecommunications Engineering and Naval Architecture, University of Genoa, Via Opera Pia 11a, Genova (Italy)

2014-02-15

In this paper we provide an experimental characterization of creep and hysteresis in a multi-layer piezoelectric actuator (PEA), taking into account their relationships in terms of memory structure. We fit the well-known log-t model to the response of the PEA when driven by piecewise-constant signals, and find that both the instantaneous and the delayed response of the PEA display hysteretic dependence on the voltage level. We investigate experimentally the dependence of the creep coefficient on the input history, by driving the PEA along first-order reversal curves and congruent minor loops, and find that it displays peculiar features like strict congruence of the minor loops and discontinuities. We finally explain the observed experimental behaviors in terms of a slow relaxation of the staircase interface line in the Preisach plane.

Memory characteristics of hysteresis and creep in multi-layer piezoelectric actuators: An experimental analysis

CERN Document Server

Biggio, Matteo; Giustiniani, Alessandro; Masi, Alessandro; Storace, Marco

2014-01-01

In this paper we provide an experimental characterization of creep and hysteresis in a multi layer piezoelectric actuator (PEA), taking into account their relationships in terms of memory structure. We fit the well-known log-t model to the response of the PEA when driven by piecewise-constant signals, and find that both the instantaneous and the delayed response of the PEA display hysteretic dependence on the voltage level. We investigate experimentally the dependence of the creep coefficient on the input history, by driving the PEA along first order reversal curves and congruent minor loops, and find that it displays peculiar features like strict congruence of the minor loops and discontinuities. We finally explain the observed experimental behaviors in terms of a slow relaxation of the staircase interface line in the Preisach plane.

Design and characterization of low-cost fabric-based flat pneumatic actuators for soft assistive glove application.

Science.gov (United States)

Yap, Hong Kai; Sebastian, Frederick; Wiedeman, Christopher; Yeow, Chen-Hua

2017-07-01

We present the design of low-cost fabric-based Hat pneumatic actuators for soft assistive glove application. The soft assistive glove is designed to assist hand impaired patients in performing activities of daily living and rehabilitation. The actuators consist of flexible materials such as fabric and latex bladder. Using zero volume actuation concept, the 2D configuration of the actuators simplifies the manufacturing process and allows the actuators to be more compact. The actuators achieve bi-directional flexion and extension motions. Compared to previously developed inflatable soft actuators, the actuators generate sufficient force and torque to assist in both finger flexion and extension at lower air pressure. Preliminary evaluation results show that the glove is able to provide both active finger flexion and extension assistance for activities of daily living and rehabilitative training.

Electrostatic actuation and electromechanical switching behavior of one-dimensional nanostructures.

Science.gov (United States)

Subramanian, Arunkumar; Alt, Andreas R; Dong, Lixin; Kratochvil, Bradley E; Bolognesi, Colombo R; Nelson, Bradley J

2009-10-27

We report on the electromechanical actuation and switching performance of nanoconstructs involving doubly clamped, individual multiwalled carbon nanotubes. Batch-fabricated, three-state switches with low ON-state voltages (6.7 V average) are demonstrated. A nanoassembly architecture that permits individual probing of one device at a time without crosstalk from other nanotubes, which are originally assembled in parallel, is presented. Experimental investigations into device performance metrics such as hysteresis, repeatability and failure modes are presented. Furthermore, current-driven shell etching is demonstrated as a tool to tune the nanomechanical clamping configuration, stiffness, and actuation voltage of fabricated devices. Computational models, which take into account the nonlinearities induced by stress-stiffening of 1-D nanowires at large deformations, are presented. Apart from providing accurate estimates of device performance, these models provide new insights into the extension of stable travel range in electrostatically actuated nanowire-based constructs as compared to their microscale counterparts.

Optimization of sensing and feedback control for vibration/flutter of rotating disk by PZT actuators via air coupled pressure.

Science.gov (United States)

Yan, Tianhong; Xu, Xinsheng; Han, Jianqiang; Lin, Rongming; Ju, Bingfeng; Li, Qing

2011-01-01

In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT) actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin's discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

Digital Control of a High Voltage (2.5 kV) Bidirectional Flyback DC-DC Converter for Driving a Capacitive Incremental Actuator

DEFF Research Database (Denmark)

Thummala, Prasanth; Maksimovic, Dragan; Zhang, Zhe

2016-01-01

This paper presents a digital control technique to achieve valley switching in a bidirectional flyback converter used to drive a dielectric electro-active polymer based capacitive incremental actuator. The paper also provides the design of a low input voltage (24 V) and variable high output voltage...... on the output high-voltage (HV) side. Experimental results verifying the bidirectional operation of a high voltage flyback converter are presented, using a 3 kV polypropylene film capacitor as the load. The energy loss distributions of the converter when 4 kV and 4.5 kV HV MOSFETs are used on HV side...

Microwave Power for Smart Membrane Actuators

Science.gov (United States)

Choi, Sang H.; Song, Kyo D.; Golembiewski, Walter T.; Chu, Sang-Hyon; King, Glen C.

2002-01-01

The concept of microwave-driven smart membrane actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. A large, ultra-light space structure, such as solar sails and Gossamer spacecrafts, requires a distribution of power into individual membrane actuators to control them in an effective way. A patch rectenna array with a high voltage output was developed to drive smart membrane actuators. Networked patch rectenna array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is developed and tested for networking a rectenna/actuator patch array. For the future development, the PAD circuit could be imbedded into a single embodiment of rectenna and actuator array with the thin-film microcircuit embodiment. Preliminary design and fabrication of PAD circuitry that consists of a sixteen nodal elements were made for laboratory testing.

ToF-SIMS characterization of silk fibroin and polypyrrole composite actuators

Energy Technology Data Exchange (ETDEWEB)

Bradshaw, Nathan P.; Severt, Sean Y.; Wang, Zhaoying; Fengel, Carly V.; Larson, Jesse D.; Zhu, Zihua; Murphy, Amanda R.; Leger., Janelle M.

2015-11-01

Biocompatible materials capable of controlled actuation under biologically relevant conditions are in high demand for use in a number of biomedical applications. Recently, we demonstrated that a composite material composed of silk biopolymer and the conducting polymer poly(pyrrole) can bend under an applied voltage using a simple bilayer device. Here we present further characterization of these bilayer actuators using time of flight secondary ion mass spectrometry, and provide clarification on the mechanism of actuation and factors affecting device performance and stability. We will discuss the results of this study in the context of strategies for optimization of device performance.

Effect of stiffness and movement speed on selected dynamic torque characteristics of hydraulic-actuation joystick controls for heavy vehicles.

Science.gov (United States)

Oliver, Michele; Rogers, Robert; Rickards, Jeremy; Tingley, Maureen; Biden, Edmund

2006-02-22

The purpose of this work was to quantify the effects of joystick stiffness and movement speed on the dynamic torque characteristics of hydraulic-actuation joystick controls, as found in off-road vehicles, as one of the initial steps towards the development of a joystick design protocol. Using a previously developed mathematical model in which a hydraulic-actuation joystick is assumed to rotate about two axes where the rotation origin is a universal joint, the dynamic torque characteristics incurred by an operator were predicted. Utilizing a laboratory mock-up of an excavator cab environment, three actuation torque characteristics (peak torque, angular impulse and deceleration at the hard endpoint) were quantified for nine unskilled joystick operators during the use of a commonly used North American hydraulic-actuation joystick. The six different experimental conditions included combinations of three joystick stiffnesses and two movement speeds. The highest instantaneous input torque over the course of the joystick movement (not including the hard endpoint) was evaluated using the peak torque value. Angular impulse provided an indication of the sustained exposure to force. The third indicator, deceleration at the hard endpoint, was included to provide a description of impact loading on the hand as the joystick came to a sudden stop. The most important result of this work is that the dynamic torque characteristics incurred during hydraulic-actuation joystick use are substantial. While the peak torque values were not very different between the fast and slow motion conditions, the high decelerations even for slow movements observed at maximum excursion of the joystick indicate that the dynamics do matter. On the basis of deceleration at the hard endpoint and peak torque, the joystick movements that require the highest values for a combination of torque variables are the side-to-side ones. This suggests that less stiff balance and return springs should be considered for

Synthetic jet actuation for load control

NARCIS (Netherlands)

de Vries, Hein; van der Weide, Edwin Theodorus Antonius; Hoeijmakers, Hendrik Willem Marie

2014-01-01

The reduction of wind turbine blade loads is an important issue in the reduction of the costs of energy production. Reduction of the loads of a non-cyclic nature requires so-called smart rotor control, which involves the application of distributed actuators and sensors to provide fast and local

A Four-Feet Walking-Type Rotary Piezoelectric Actuator with Minute Step Motion.

Science.gov (United States)

Liu, Yingxiang; Wang, Yun; Liu, Junkao; Xu, Dongmei; Li, Kai; Shan, Xiaobiao; Deng, Jie

2018-05-08

A four-feet walking-type rotary piezoelectric actuator with minute step motion was proposed. The proposed actuator used the rectangular motions of four driving feet to push the rotor step-by-step; this operating principle was different with the previous non-resonant actuators using direct-driving, inertial-driving, and inchworm-type mechanisms. The mechanism of the proposed actuator was discussed in detail. Transient analyses were accomplished by ANSYS software to simulate the motion trajectory of the driving foot and to find the response characteristics. A prototype was manufactured to verify the mechanism and to test the mechanical characteristics. A minimum resolution of 0.095 μrad and a maximum torque of 49 N·mm were achieved by the prototype, and the output speed was varied by changing the driving voltage and working frequency. This work provides a new mechanism for the design of a rotary piezoelectric actuator with minute step motion.

Soft actuators and soft actuating devices

Energy Technology Data Exchange (ETDEWEB)

Yang, Dian; Whitesides, George M.

2017-10-17

A soft buckling linear actuator is described, including: a plurality of substantially parallel bucklable, elastic structural components each having its longest dimension along a first axis; and a plurality of secondary structural components each disposed between and bridging two adjacent bucklable, elastic structural components; wherein every two adjacent bucklable, elastic structural components and the secondary structural components in-between define a layer comprising a plurality of cells each capable of being connected with a fluid inflation or deflation source; the secondary structural components from two adjacent layers are not aligned along a second axis perpendicular to the first axis; and the secondary structural components are configured not to buckle, the bucklable, elastic structural components are configured to buckle along the second axis to generate a linear force, upon the inflation or deflation of the cells. Methods of actuation using the same are also described.

Design and fabrication of a MEMS chevron-type thermal actuator

Energy Technology Data Exchange (ETDEWEB)

Baracu, Angela, E-mail: angela.baracu@imt.ro [Laboratory of Modeling, Simulation and CAD, National Institute for R and D in Microtechnologies - IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190, Bucharest, Romania and University Politehnica of Bucharest (Romania); Voicu, Rodica; Müller, Raluca; Avram, Andrei [Laboratory of Modeling, Simulation and CAD, National Institute for R and D in Microtechnologies - IMT Bucharest, 126A, Erou Iancu Nicolae Street, 077190, Bucharest (Romania); Pustan, Marius, E-mail: marius.pustan@omt.utcluj.ro; Chiorean, Radu, E-mail: marius.pustan@omt.utcluj.ro; Birleanu, Corina, E-mail: marius.pustan@omt.utcluj.ro; Dudescu, Cristian, E-mail: marius.pustan@omt.utcluj.ro [Laboratory of Micro and Nano Systems, Technical University of Cluj-Napoca, Bd. Muncii, no. 103-105, 400641 Cluj-Napoca (Romania)

2015-02-17

This paper presents the design and fabrication of a MEMS chevron-type thermal actuator. The device was designed for fabrication in the standard MEMS technology, where the topography of the upper layers depends on the patterns of structural and sacrificial layers underneath. The proposed actuator presents some advantages over usual thermal vertical chevron actuators by means of low operating voltages, high output force and linear movement without deformation of the shaft. The device simulations were done using COVENTOR software. The movement obtained by simulation was 12 μm, for a voltage of 0.2 V and the current intensity of 257 mA. The design optimizes the in-plane displacement by fixed anchors and beam inclination angle. Heating is provided by Joule dissipation. The material used for manufacture of chevron-based actuator was aluminum due to its thermal and mechanical properties. The release of the movable part was performed using isotropic dry etching by Reactive Ion Etching (RIE). A first inspection was achieved using Scanning Electron Microscope (SEM). In order to obtain the in-plane displacement we carried out electrical measurements. The thermal actuator can be used for a variety of optical and microassembling applications. This kind of thermal actuator could be integrated easily with other micro devices since its fabrication is compatible with the general semiconductor processes.

Smart Tendon Actuated Flexible Actuator

Directory of Open Access Journals (Sweden)

Md. Masum Billah

2015-01-01

Full Text Available We investigate the kinematic feasibility of a tendon-based flexible parallel platform actuator. Much of the research on tendon-driven Stewart platforms is devoted either to the completely restrained positioning mechanism (CRPM or to one particular type of the incompletely restrained positioning mechanism (IRPM where the external force is provided by the gravitational pull on the platform such as in cable-suspended Stewart platforms. An IRPM-based platform is proposed which uses the external force provided by a compliant member. The compliant central column allows the configuration to achieve n DOFs with n tendons. In particular, this investigation focuses on the angular deflection of the upper platform with respect to the lower platform. The application here is aimed at developing a linkable module that can be connected to one another so as to form a “snake robot” of sorts. Since locomotion takes precedence over positioning in this application, a 3-DOF Stewart platform is adopted. For an arbitrary angular displace of the end-effector, the corresponding length of each tendon can be determined through inverse kinematics. Mathematical singularities are investigated using the traditional analytical method of defining the Jacobian.

Bi-stable optical actuator

Science.gov (United States)

Holdener, Fred R.; Boyd, Robert D.

2000-01-01

The present invention is a bi-stable optical actuator device that is depowered in both stable positions. A bearing is used to transfer motion and smoothly transition from one state to another. The optical actuator device may be maintained in a stable position either by gravity or a restraining device.

Finite element analysis and validation of dielectric elastomer actuators used for active origami

International Nuclear Information System (INIS)

McGough, Kevin; Ahmed, Saad; Frecker, Mary; Ounaies, Zoubeida

2014-01-01

The field of active origami explores the incorporation of active materials into origami-inspired structures in order to serve as a means of actuation. Active origami-inspired structures capable of folding into complex three-dimensional (3D) shapes have the potential to be lightweight and versatile compared to traditional methods of actuation. This paper details the finite element analysis and experimental validation of unimorph actuators. Actuators are fabricated by adhering layers of electroded dielectric elastomer (3M VHB F9473PC) onto a passive substrate layer (3M Magic Scotch Tape). Finite element analysis of the actuators simulates the electromechanical coupling of the dielectric elastomer under an applied voltage by applying pressures to the surfaces of the dielectric elastomer where the compliant electrode (conductive carbon grease) is present. 3D finite element analysis of the bending actuators shows that applying contact boundary conditions to the electroded region of the active and passive layers provides better agreement to experimental data compared to modeling the entire actuator as continuous. To improve the applicability of dielectric elastomer-based actuators for active origami-inspired structures, folding actuators are developed by taking advantage of localized deformation caused by a passive layer with non-uniform thickness. Two-dimensional analysis of the folding actuators shows that agreement to experimental data diminishes as localized deformation increases. Limitations of using pressures to approximate the electromechanical coupling of the dielectric elastomer under an applied electric field and additional modeling considerations are also discussed. (paper)

Magnetic suspension characteristics of electromagnetic actuators

Science.gov (United States)

Rao, Dantam K.; Dill, J.; Zorzi, E.

1993-01-01

Electromagnetic actuators that use a current-carrying coil (which is placed in a magnetic field) to generate mechanical force are conceptually attractive components for active control of rotating shafts. In one concept that is being tested in the laboratory, the control forces from such actuators are applied on the flexibly supported bearing housings of the rotor. Development of this concept into a practical reality requires a clear and thorough understanding of the role of electromechanical parameters of these actuators in delivering the right amount of control force at the right phase into the rotor. The electromechanical parameters of the actuators investigated are the mass of the armature, stiffness of its suspension, electrical resistance, and inductance of the coils. Improper selection of these parameters can result in degradation in their performance, leading to mistuning between the actuator and the rotor. Through a simple analysis, it is shown that use of such mistuned actuators could result in sharp fluctuations in the phase of the control force delivered into the rotor around the critical speeds. These sharp fluctuations in phase, called 'Phase Glitches', are undesirable. Hence, future designs of controllers should take into account the undesirable mistuning effects between the actuator and the rotor caused by the phase glitches.

Smart film actuators using biomass plastic

International Nuclear Information System (INIS)

Yoneyama, Satoshi; Tanaka, Nobuo

2011-01-01

This paper presents a novel smart film actuator based on the use of a biomass plastic as a piezoelectric film. Conventional polymeric smart sensors and actuators have been based upon synthetic piezoelectric polymer films such as PVDF. Almost all synthetic polymers are made from nearly depleted oil resources. In addition combustion of their materials releases carbon dioxide, thereby contributing to global warming. Thus at least two important sustainability principles are violated when employing synthetic polymers: avoiding depletable resources and avoiding ecosystem destruction. To overcome such problems, industrial plastic products made from synthetic polymers were developed to replace oil-based plastics with biomass plastics. This paper applies a biomass plastic with piezoelectricity such as poly-L-lactic acid (PLLA). As a result, PLLA film becomes a distributed parameter actuator per se, hence an environmentally conscious smart film actuator is developed. Firstly, this paper overviews the fundamental properties of piezoelectric synthetic polymers and biopolymers. The concept of carbon neutrality using biopolymers is mentioned. Then a two-dimensional modal actuator for exciting a specific structural mode is proposed. Furthermore, a biomass plastic-based cantilever beam with the capability of modal actuation is developed, the validity of the proposed smart film actuator based upon a biomass plastic being analytically as well as experimentally verified

Experimental identification of piezo actuator characteristic

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Ľ. Miková

2015-01-01

Full Text Available This paper deals with piezoelectric material, which can be used as actuator for conversion of electrical energy to mechanical work. Test equipment has been developed for experimental testing of the piezoactuators. Piezoactivity of this actuator has non-linear characteristic. This type of actuator is used for in-pipe mechanism design.

Thermomechanical behavior of a two-way shape memory composite actuator

International Nuclear Information System (INIS)

Ge, Qi; Westbrook, Kristofer K; Dunn, Martin L; Jerry Qi, H; Mather, Patrick T

2013-01-01

Shape memory polymers (SMPs) are a class of smart materials that can fix a temporary shape and recover to their permanent (original) shape in response to an environmental stimulus such as heat, electricity, or irradiation, among others. Most SMPs developed in the past can only demonstrate the so-called one-way shape memory effect; i.e., one programming step can only yield one shape memory cycle. Recently, one of the authors (Mather) developed a SMP that exhibits both one-way shape memory (1W-SM) and two-way shape memory (2W-SM) effects (with the assistance of an external load). This SMP was further used to develop a free-standing composite actuator with a nonlinear reversible actuation under thermal cycling. In this paper, a theoretical model for the PCO SMP based composite actuator was developed to investigate its thermomechanical behavior and the mechanisms for the observed phenomena during the actuation cycles, and to provide insight into how to improve the design. (paper)

35 Hz shape memory alloy actuator with bending-twisting mode.

Science.gov (United States)

Song, Sung-Hyuk; Lee, Jang-Yeob; Rodrigue, Hugo; Choi, Ik-Seong; Kang, Yeon June; Ahn, Sung-Hoon

2016-02-19

Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators.

The effects of additives on the actuating performances of a dielectric elastomer actuator

International Nuclear Information System (INIS)

Nguyen, Huu Chuc; Doan, Vu Thuy; Park, JongKil; Koo, Ja Choon; Choi, Hyouk Ryeol; Lee, Youngkwan; Nam, Jae-do

2009-01-01

This paper presents a comprehensive study of the effects of additives on the performance of a dielectric elastomer actuator. Previously, a new dielectric elastomer material, called 'synthetic elastomer', was presented for the means of actuation, which permits changes in the mechanical as well as the electrical properties in order to meet the requirements of certain applications. This work studies how the electromechanical properties of the synthetic elastomer can be adjusted by combining two additives, namely dioctyl phthalate (DOP) and titanium dioxide (TiO 2 ). Experiments are carried out and the effects of each additive are compared to one another based on the actuation performances

Soft Pneumatic Actuators for Rehabilitation

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Guido Belforte

2014-05-01

Full Text Available Pneumatic artificial muscles are pneumatic devices with practical and various applications as common actuators. They, as human muscles, work in agonistic-antagonistic way, giving a traction force only when supplied by compressed air. The state of the art of soft pneumatic actuators is here analyzed: different models of pneumatic muscles are considered and evolution lines are presented. Then, the use of Pneumatic Muscles (PAM in rehabilitation apparatus is described and the general characteristics required in different applications are considered, analyzing the use of proper soft actuators with various technical properties. Therefore, research activity carried out in the Department of Mechanical and Aerospace Engineering in the field of soft and textile actuators is presented here. In particular, pneumatic textile muscles useful for active suits design are described. These components are made of a tubular structure, with an inner layer of latex coated with a deformable outer fabric sewn along the edge. In order to increase pneumatic muscles forces and contractions Braided Pneumatic Muscles are studied. In this paper, new prototypes are presented, based on a fabric construction and various kinds of geometry. Pressure-force-deformation tests results are carried out and analyzed. These actuators are useful for rehabilitation applications. In order to reproduce the whole upper limb movements, new kind of soft actuators are studied, based on the same principle of planar membranes deformation. As an example, the bellows muscle model and worm muscle model are developed and described. In both cases, wide deformations are expected. Another issue for soft actuators is the pressure therapy. Some textile sleeve prototypes developed for massage therapy on patients suffering of lymph edema are analyzed. Different types of fabric and assembly techniques have been tested. In general, these Pressure Soft Actuators are useful for upper/lower limbs treatments

Magnetic Actuation of Biological Systems

Science.gov (United States)

Lauback, Stephanie D.

Central to the advancement of many biomedical and nanotechnology capabilities is the capacity to precisely control the motion of micro and nanostructures. These applications range from single molecule experiments to cell isolation and separation, to drug delivery and nanomachine manipulation. This dissertation focuses on actuation of biological micro- and nano-entities through the use of weak external magnetic fields, superparamagnetic beads, and ferromagnetic thin films. The magnetic platform presents an excellent method for actuation of biological systems due to its ability to directly control the motion of an array of micro and nanostructures in real-time with calibrated picoNewton forces. The energy landscape of two ferromagnetic thin film patterns (disks and zigzag wires) is experimentally explored and compared to corresponding theoretical models to quantify the applied forces and trajectories of superparamagnetic beads due to the magnetic traps. A magnetic method to directly actuate DNA nanomachines in real-time with nanometer resolution and sub-second response times using micromagnetic control was implemented through the use of stiff DNA micro-levers which bridged the large length scale mismatch between the micro-actuator and the nanomachine. Compared to current alternative methods which are limited in the actuation speeds and the number of reconfiguration states of DNA constructs, this magnetic approach enables fast actuation (˜ milliseconds) and reconfigurable conformations achieved through a continuous range of finely tuned steps. The system was initially tested through actuation of the stiff arm tethered to the surface, and two prototype DNA nanomachines (rotor and hinge) were successfully actuated using the stiff mechanical lever. These results open new possibilities in the development of functional robotic systems at the molecular scale. In exploiting the use of DNA stiff levers, a new technique was also developed to investigate the emergence of the

A bidirectional shape memory alloy folding actuator

International Nuclear Information System (INIS)

Paik, Jamie K; Wood, Robert J

2012-01-01

This paper presents a low-profile bidirectional folding actuator based on annealed shape memory alloy sheets applicable for meso- and microscale systems. Despite the advantages of shape memory alloys—high strain, silent operation, and mechanical simplicity—their application is often limited to unidirectional operation. We present a bidirectional folding actuator that produces two opposing 180° motions. A laser-patterned nickel alloy (Inconel 600) heater localizes actuation to the folding sections. The actuator has a thin ( < 1 mm) profile, making it appropriate for use in robotic origami. Various design parameters and fabrication variants are described and experimentally explored in the actuator prototype. (paper)

Reliable actuators for twin rotor MIMO system

Science.gov (United States)

Rao, Vidya S.; V. I, George; Kamath, Surekha; Shreesha, C.

2017-11-01

Twin Rotor MIMO System (TRMS) is a bench mark system to test flight control algorithms. One of the perturbations on TRMS which is likely to affect the control system is actuator failure. Therefore, there is a need for a reliable control system, which includes H infinity controller along with redundant actuators. Reliable control refers to the design of a control system to tolerate failures of a certain set of actuators or sensors while retaining desired control system properties. Output of reliable controller has to be transferred to the redundant actuator effectively to make the TRMS reliable even under actual actuator failure.

Novel compliant actuator for wearable robotics applications.

Science.gov (United States)

Claros, M; Soto, R; Rodríguez, J J; Cantú, C; Contreras-Vidal, José L

2013-01-01

In the growing fields of wearable robotics, rehabilitation robotics, prosthetics, and walking robots, variable impedance and force actuators are being designed and implemented because of their ability to dynamically modulate the intrinsic viscoelastic properties such as stiffness and damping. This modulation is crucial to achieve an efficient and safe human-robot interaction that could lead to electronically generate useful emergent dynamical behaviors. In this work we propose a novel actuation system in which is implemented a control scheme based on equilibrium forces for an active joint capable to provide assistance/resistance as needed and also achieve minimal mechanical impedance when tracking the movement of the user limbs. The actuation system comprises a DC motor with a built in speed reducer, two force-sensing resistors (FSR), a mechanism which transmits to the FSRs the torque developed in the joint and a controller which regulate the amount of energy that is delivered to the DC motor. The proposed system showed more impedance reduction, by the effect of the controlled contact forces, compared with the ones in the reviewed literature.

Self-Sensing Ionic Polymer Actuators: A Review

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Karl Kruusamäe

2015-03-01

Full Text Available Ionic electromechanically active polymers (IEAP are laminar composites that can be considered attractive candidates for soft actuators. Their outstanding properties such as low operating voltage, easy miniaturization, and noiseless operation are, however, marred by issues related to the repeatability in the production and operation of these materials. Implementing closed-loop control for IEAP actuators is a viable option for overcoming these issues. Since IEAP laminates also behave as mechanoelectrical sensors, it is advantageous to combine the actuating and sensing functionalities of a single device to create a so-called self-sensing actuator. This review article systematizes the state of the art in producing self-sensing ionic polymer actuators. The IEAPs discussed in this paper are conducting (or conjugated polymers actuators (CPA, ionic polymer-metal composite (IPMC, and carbonaceous polymer laminates.

Nonlinear vibration of an electrically actuated microresonator tuned by combined DC piezoelectric and electric actuations

International Nuclear Information System (INIS)

Zamanian, M; Khadem, S E

2010-01-01

This paper studies the nonlinear vibration of a clamped–clamped microresonator under combined electric and piezoelectric actuations. The electric actuation is induced by applying an AC–DC voltage between the microbeam and the electrode plate that lies on opposite sides of the microbeam, and the piezoelectric actuation is induced by applying the DC voltage between upper and lower sides of the piezoelectric layer deposited on the microbeam length. It is assumed that the neutral axis of bending is stretched when the microbeam is deflected. The equations of motion are derived using Newton's second law, and are solved using the multiple-scale perturbation method. It is shown that, depending on the value of DC electric and piezoelectric actuations, geometry and the bending stiffness of the system. A softening or hardening behavior may be realized. It demonstrates that nonlinear behavior of an electrically actuated microresonator may be tuned to a linear behavior by applying a convenient DC electric voltage to the piezoelectric layer, and so an undesirable shift of resonance frequency may be removed. If one lets the applied voltage to the piezoelectric layer be equal to zero, this paper would be an effort to tailor the linear and nonlinear stiffness coefficients of two layered electrically actuated microresonators without the assumption that the lengths of the two layers are equal

A magnetically actuated, high momentum rate MEMS pulsed microjet for active flow control

International Nuclear Information System (INIS)

Ducloux, O; Viard, R; Talbi, A; Pernod, P; Preobrazhensky, V; Gimeno, L; Merlen, A; Deblock, Y

2009-01-01

A small-sized, high momentum rate (>10 −2 N), dynamically actuated microvalve fulfilling the functional specifications for active aerodynamic flow control was designed, fabricated and characterized. The prototype consists of a microfabricated silicon channel pinched by an actuated poly(dimethyl siloxane) (PDMS) polymer membrane. Actuation is provided by coupling an inductive driving coil and a NdFeB permanent magnet fixed on the PDMS elastomeric membrane. The development of a specific microfabrication process, and a complete characterization of the fabricated prototypes are presented in this paper. The yield air microjet performances reach 150 m s −1 for an actuation frequency situated in the range [0 Hz–400 Hz] and an outlet area of about 1 mm 2 . Experimental results also show that the use of a vectoring plate placed at the outlet of the microvalve provided not only easier integration of the microsystem, but also improved the penetration of the microjet into the main flow

Optimization of Sensing and Feedback Control for Vibration/Flutter of Rotating Disk by PZT Actuators via Air Coupled Pressure

Directory of Open Access Journals (Sweden)

Bingfeng Ju

2011-03-01

Full Text Available In this paper, a feedback control mechanism and its optimization for rotating disk vibration/flutter via changes of air-coupled pressure generated using piezoelectric patch actuators are studied. A thin disk rotates in an enclosure, which is equipped with a feedback control loop consisting of a micro-sensor, a signal processor, a power amplifier, and several piezoelectric (PZT actuator patches distributed on the cover of the enclosure. The actuator patches are mounted on the inner or the outer surfaces of the enclosure to produce necessary control force required through the airflow around the disk. The control mechanism for rotating disk flutter using enclosure surfaces bonded with sensors and piezoelectric actuators is thoroughly studied through analytical simulations. The sensor output is used to determine the amount of input to the actuator for controlling the response of the disk in a closed loop configuration. The dynamic stability of the disk-enclosure system, together with the feedback control loop, is analyzed as a complex eigenvalue problem, which is solved using Galerkin’s discretization procedure. The results show that the disk flutter can be reduced effectively with proper configurations of the control gain and the phase shift through the actuations of PZT patches. The effectiveness of different feedback control methods in altering system characteristics and system response has been investigated. The control capability, in terms of control gain, phase shift, and especially the physical configuration of actuator patches, are also evaluated by calculating the complex eigenvalues and the maximum displacement produced by the actuators. To achieve a optimal control performance, sizes, positions and shapes of PZT patches used need to be optimized and such optimization has been achieved through numerical simulations.

Hydraulically actuated artificial muscles

Science.gov (United States)

Meller, M. A.; Tiwari, R.; Wajcs, K. B.; Moses, C.; Reveles, I.; Garcia, E.

2012-04-01

Hydraulic Artificial Muscles (HAMs) consisting of a polymer tube constrained by a nylon mesh are presented in this paper. Despite the actuation mechanism being similar to its popular counterpart, which are pneumatically actuated (PAM), HAMs have not been studied in depth. HAMs offer the advantage of compliance, large force to weight ratio, low maintenance, and low cost over traditional hydraulic cylinders. Muscle characterization for isometric and isobaric tests are discussed and compared to PAMs. A model incorporating the effect of mesh angle and friction have also been developed. In addition, differential swelling of the muscle on actuation has also been included in the model. An application of lab fabricated HAMs for a meso-scale robotic system is also presented.

Shape-Memory-Alloy Actuator For Flight Controls

Science.gov (United States)

Barret, Chris

1995-01-01

Report proposes use of shape-memory-alloy actuators, instead of hydraulic actuators, for aerodynamic flight-control surfaces. Actuator made of shape-memory alloy converts thermal energy into mechanical work by changing shape as it makes transitions between martensitic and austenitic crystalline phase states of alloy. Because both hot exhaust gases and cryogenic propellant liquids available aboard launch rockets, shape-memory-alloy actuators exceptionally suited for use aboard such rockets.

Active control of sound transmission through a rectangular panel using point-force actuators and piezoelectric film sensors.

Science.gov (United States)

Sanada, Akira; Higashiyama, Kouji; Tanaka, Nobuo

2015-01-01

This study deals with the active control of sound transmission through a rectangular panel, based on single input, single output feedforward vibration control using point-force actuators and piezoelectric film sensors. It focuses on the phenomenon in which the sound power transmitted through a finite-sized panel drops significantly at some frequencies just below the resonance frequencies of the panel in the low-frequency range as a result of modal coupling cancellation. In a previous study, it was shown that when point-force actuators are located on nodal lines for the frequency at which this phenomenon occurs, a force equivalent to the incident sound wave can act on the panel. In this study, a practical method for sensing volume velocity using a small number of piezoelectric film strips is investigated. It is found that two quadratically shaped piezoelectric film strips, attached at the same nodal lines as those where the actuators were placed, can sense the volume velocity approximately in the low-frequency range. Results of simulations show that combining the proposed actuation method and the sensing method can achieve a practical control effect at low frequencies over a wide frequency range. Finally, experiments are carried out to demonstrate the validity and feasibility of the proposed method.

Performance study of a hydrogen powered metal hydride actuator

International Nuclear Information System (INIS)

Bhuiya, Md Mainul Hossain; Kim, Kwang J

2016-01-01

A thermally driven hydrogen powered actuator integrating metal hydride hydrogen storage reactor, which is compact, noiseless, and able to generate smooth actuation, is presented in this article. To test the plausibility of a thermally driven actuator, a conventional piston type actuator was integrated with LaNi 5 based hydrogen storage system. Copper encapsulation followed by compaction of particles into pellets, were adopted to improve overall thermal conductivity of the reactor. The operation of the actuator was thoroughly investigated for an array of operating temperature ranges. Temperature swing of the hydride reactor triggering smooth and noiseless actuation over several operating temperature ranges were monitored for quantification of actuator efficiency. Overall, the actuator generated smooth and consistent strokes during repeated cycles of operation. The efficiency of the actuator was found to be as high as 13.36% for operating a temperature range of 20 °C–50 °C. Stress–strain characteristics, actuation hysteresis etc were studied experimentally. Comparison of stress–strain characteristics of the proposed actuator with traditional actuators, artificial muscles and so on was made. The study suggests that design modification and use of high pressure hydride may enhance the performance and broaden the application horizon of the proposed actuator in future. (paper)

Cyclic degradation of antagonistic shape memory actuated structures

International Nuclear Information System (INIS)

Sofla, A Y N; Elzey, D M; Wadley, H N G

2008-01-01

Antagonistic shape memory actuated structures exploit opposing pairs of one-way shape memory alloy (SMA) linear actuators to create devices capable of a fully reversible response. Unlike many conventional reversible SMA devices they do not require bias force components (springs) to return them to their pre-actuated configuration. However, the repeated use of SMA antagonistic devices results in the accumulation of plastic strain in the actuators which can diminish their actuation stroke. We have investigated this phenomenon and the effect of shape memory alloy pre-strain upon it for near equi-atomic NiTi actuators. We find that the degradation eventually stabilizes during cycling. A thermomechanical treatment has been found to significantly reduce degradation in cyclic response of the actuators

ARMin III – Arm Therapy Exoskeleton with an Ergonomic Shoulder Actuation

Directory of Open Access Journals (Sweden)

Tobias Nef

2009-01-01

Full Text Available Rehabilitation robots have become important tools in stroke rehabilitation. Compared to manual arm training, robot-supported training can be more intensive, of longer duration and more repetitive. Therefore, robots have the potential to improve the rehabilitation process in stroke patients. Whereas a majority of previous work in upper limb rehabilitation robotics has focused on end-effector-based robots, a shift towards exoskeleton robots is taking place because they offer a better guidance of the human arm, especially for movements with a large range of motion. However, the implementation of an exoskeleton device introduces the challenge of reproducing the motion of the human shoulder, which is one of the most complex joints of the body. Thus, this paper starts with describing a simplified model of the human shoulder. On the basis of that model, a new ergonomic shoulder actuation principle that provides motion of the humerus head is proposed, and its implementation in the ARMin III arm therapy robot is described. The focus lies on the mechanics and actuation principle. The ARMin III robot provides three actuated degrees of freedom for the shoulder and one for the elbow joint. An additional module provides actuated lower arm pro/supination and wrist flexion/extension. Five ARMin III devices have been manufactured and they are currently undergoing clinical evaluation in hospitals in Switzerland and in the United States.

Thermally Actuated Hydraulic Pumps

Science.gov (United States)

Jones, Jack; Ross, Ronald; Chao, Yi

2008-01-01

Thermally actuated hydraulic pumps have been proposed for diverse applications in which direct electrical or mechanical actuation is undesirable and the relative slowness of thermal actuation can be tolerated. The proposed pumps would not contain any sliding (wearing) parts in their compressors and, hence, could have long operational lifetimes. The basic principle of a pump according to the proposal is to utilize the thermal expansion and contraction of a wax or other phase-change material in contact with a hydraulic fluid in a rigid chamber. Heating the chamber and its contents from below to above the melting temperature of the phase-change material would cause the material to expand significantly, thus causing a substantial increase in hydraulic pressure and/or a substantial displacement of hydraulic fluid out of the chamber. Similarly, cooling the chamber and its contents from above to below the melting temperature of the phase-change material would cause the material to contract significantly, thus causing a substantial decrease in hydraulic pressure and/or a substantial displacement of hydraulic fluid into the chamber. The displacement of the hydraulic fluid could be used to drive a piston. The figure illustrates a simple example of a hydraulic jack driven by a thermally actuated hydraulic pump. The pump chamber would be a cylinder containing encapsulated wax pellets and containing radial fins to facilitate transfer of heat to and from the wax. The plastic encapsulation would serve as an oil/wax barrier and the remaining interior space could be filled with hydraulic oil. A filter would retain the encapsulated wax particles in the pump chamber while allowing the hydraulic oil to flow into and out of the chamber. In one important class of potential applications, thermally actuated hydraulic pumps, exploiting vertical ocean temperature gradients for heating and cooling as needed, would be used to vary hydraulic pressures to control buoyancy in undersea research

A swimming robot actuated by living muscle tissue

Directory of Open Access Journals (Sweden)

Herr Hugh

2004-10-01

Full Text Available Abstract Biomechatronics is the integration of biological components with artificial devices, in which the biological component confers a significant functional capability to the system, and the artificial component provides specific cellular and tissue interfaces that promote the maintenance and functional adaptation of the biological component. Based upon functional performance, muscle is potentially an excellent mechanical actuator, but the larger challenge of developing muscle-actuated, biomechatronic devices poses many scientific and engineering challenges. As a demonstratory proof of concept, we designed, built, and characterized a swimming robot actuated by two explanted frog semitendinosus muscles and controlled by an embedded microcontroller. Using open loop stimulation protocols, the robot performed basic swimming maneuvers such as starting, stopping, turning (turning radius ~400 mm and straight-line swimming (max speed >1/3 body lengths/second. A broad spectrum antibiotic/antimycotic ringer solution surrounded the muscle actuators for long term maintenance, ex vivo. The robot swam for a total of 4 hours over a 42 hour lifespan (10% duty cycle before its velocity degraded below 75% of its maximum. The development of functional biomechatronic prototypes with integrated musculoskeletal tissues is the first critical step toward the long term objective of controllable, adaptive and robust biomechatronic robots and prostheses.

Application of magnetohydrodynamic actuation to continuous flow chemistry.

Science.gov (United States)

West, Jonathan; Karamata, Boris; Lillis, Brian; Gleeson, James P; Alderman, John; Collins, John K; Lane, William; Mathewson, Alan; Berney, Helen

2002-11-01

Continuous flow microreactors with an annular microchannel for cyclical chemical reactions were fabricated by either bulk micromachining in silicon or by rapid prototyping using EPON SU-8. Fluid propulsion in these unusual microchannels was achieved using AC magnetohydrodynamic (MHD) actuation. This integrated micropumping mechanism obviates the use of moving parts by acting locally on the electrolyte, exploiting its inherent conductive nature. Both silicon and SU-8 microreactors were capable of MHD actuation, attaining fluid velocities of the order of 300 microm s(-1) when using a 500 mM KCl electrolyte. The polymerase chain reaction (PCR), a thermocycling process, was chosen as an illustrative example of a cyclical chemistry. Accordingly, temperature zones were provided to enable a thermal cycle during each revolution. With this approach, fluid velocity determines cycle duration. Here, we report device fabrication and performance, a model to accurately describe fluid circulation by MHD actuation, and compatibility issues relating to this approach to chemistry.

Hysteresis modeling of magnetic shape memory alloy actuator based on Krasnosel'skii-Pokrovskii model.

Science.gov (United States)

Zhou, Miaolei; Wang, Shoubin; Gao, Wei

2013-01-01

As a new type of intelligent material, magnetically shape memory alloy (MSMA) has a good performance in its applications in the actuator manufacturing. Compared with traditional actuators, MSMA actuator has the advantages as fast response and large deformation; however, the hysteresis nonlinearity of the MSMA actuator restricts its further improving of control precision. In this paper, an improved Krasnosel'skii-Pokrovskii (KP) model is used to establish the hysteresis model of MSMA actuator. To identify the weighting parameters of the KP operators, an improved gradient correction algorithm and a variable step-size recursive least square estimation algorithm are proposed in this paper. In order to demonstrate the validity of the proposed modeling approach, simulation experiments are performed, simulations with improved gradient correction algorithm and variable step-size recursive least square estimation algorithm are studied, respectively. Simulation results of both identification algorithms demonstrate that the proposed modeling approach in this paper can establish an effective and accurate hysteresis model for MSMA actuator, and it provides a foundation for improving the control precision of MSMA actuator.

Hysteresis Modeling of Magnetic Shape Memory Alloy Actuator Based on Krasnosel'skii-Pokrovskii Model

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Miaolei Zhou

2013-01-01

Full Text Available As a new type of intelligent material, magnetically shape memory alloy (MSMA has a good performance in its applications in the actuator manufacturing. Compared with traditional actuators, MSMA actuator has the advantages as fast response and large deformation; however, the hysteresis nonlinearity of the MSMA actuator restricts its further improving of control precision. In this paper, an improved Krasnosel'skii-Pokrovskii (KP model is used to establish the hysteresis model of MSMA actuator. To identify the weighting parameters of the KP operators, an improved gradient correction algorithm and a variable step-size recursive least square estimation algorithm are proposed in this paper. In order to demonstrate the validity of the proposed modeling approach, simulation experiments are performed, simulations with improved gradient correction algorithm and variable step-size recursive least square estimation algorithm are studied, respectively. Simulation results of both identification algorithms demonstrate that the proposed modeling approach in this paper can establish an effective and accurate hysteresis model for MSMA actuator, and it provides a foundation for improving the control precision of MSMA actuator.

Materials selection and design of microelectrothermal bimaterial actuators

OpenAIRE

Prasanna, S.; Spearing, S.M.

2007-01-01

A common form of MEMS actuator is a thermally actuated bimaterial, which is easy to fabricate by surface micromachining and permits out of plane actuation, which is otherwise difficult to achieve. This paper presents an analytical framework for the design of such microelectrothermal bimaterial actuators. Mechanics relationships for a cantilever bimaterial strip subjected to a uniform temperature were applied to obtain expressions for performance metrics for the actuator, i.e., maximum work/vo...

Control of Adjustable Compliant Actuators

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Berno J.E. Misgeld

2014-05-01

Full Text Available Adjustable compliance or variable stiffness actuators comprise an additional element to elastically decouple the actuator from the load and are increasingly applied to human-centered robotic systems. The advantages of such actuators are of paramount importance in rehabilitation robotics, where requirements demand safe interaction between the therapy system and the patient. Compliant actuator systems enable the minimization of large contact forces arising, for example, from muscular spasticity and have the ability to periodically store and release energy in cyclic movements. In order to overcome the loss of bandwidth introduced by the elastic element and to guarantee a higher range in force/torque generation, new actuator designs consider variable or nonlinear stiffness elements, respectively. These components cannot only be adapted to the walking speed or the patient condition, but also entail additional challenges for feedback control. This paper introduces a novel design method for an impedance-based controller that fulfills the control objectives and compares the performance and robustness to a classical cascaded control approach. The new procedure is developed using a non-standard positive-real Η2 controller design and is applied to a loop-shaping approach. Robust norm optimal controllers are designed with regard to the passivity of the actuator load-impedance transfer function and the servo control problem. Classical cascaded and positive-real Η2 controller designs are validated and compared in simulations and in a test bench using a passive elastic element of varying stiffness.

A multi-electrode and pre-deformed bilayer spring structure electrostatic attractive MEMS actuator with large stroke at low actuation voltage

International Nuclear Information System (INIS)

Hu, Fangrong; Li, Zhi; Xiong, Xianming; Niu, Junhao; Peng, Zhiyong; Qian, Yixian; Yao, Jun

2012-01-01

This paper presents a multi-electrode and pre-deformed bilayer spring structure electrostatic attractive microelectromechanical systems (MEMS) actuator; it has large stroke at relatively low actuation voltage. Generally, electrostatic-attractive-force-based actuators have small stroke due to the instability resulted from the electrostatic ‘pull-in’ phenomenon. However, in many applications, the electrostatic micro-actuator with large stroke at low voltage is more preferred. By introducing a multi-electrode and a pre-deformed bilayer spring structure, an electrostatic attractive MEMS actuator with large stroke at very low actuation voltage has been successfully demonstrated in this paper. The actuator contains a central plate with a size of 300 µm × 300 µm × 1.5 µm and it is supported by four L-shaped bilayer springs which are pre-deformed due to residual stresses. Each bilayer spring is simultaneously attracted by three adjacent fixed electrodes, and the factors affecting the electrostatic attractive force are analyzed by a finite element analysis method. The prototype of the actuator is fabricated by poly-multi-user-MEMS-process (PolyMUMP) and the static performance is tested using a white light interferometer. The measured stroke of the actuator reaches 2 µm at 13 V dc, and it shows a good agreement with the simulation. (paper)

L1 Adaptive Control Augmentation System with Application to the X-29 Lateral/Directional Dynamics: A Multi-Input Multi-Output Approach

Science.gov (United States)

Griffin, Brian Joseph; Burken, John J.; Xargay, Enric

2010-01-01

This paper presents an L(sub 1) adaptive control augmentation system design for multi-input multi-output nonlinear systems in the presence of unmatched uncertainties which may exhibit significant cross-coupling effects. A piecewise continuous adaptive law is adopted and extended for applicability to multi-input multi-output systems that explicitly compensates for dynamic cross-coupling. In addition, explicit use of high-fidelity actuator models are added to the L1 architecture to reduce uncertainties in the system. The L(sub 1) multi-input multi-output adaptive control architecture is applied to the X-29 lateral/directional dynamics and results are evaluated against a similar single-input single-output design approach.

Development of thermal actuators with multi-locking positions

Science.gov (United States)

Luo, J. K.; Zhu, Y.; Fu, Y. Q.; Flewitt, A. J.; Spearing, S. M.; Miao, J. M.; Milne, W. I.

2006-04-01

To reduce power consumption and operation temperature for micro-thermal actuators, metal-based micro-mechanical locks with multi-locking positions were analyzed and fabricated. The micro-locks consist of two or three U-shaped thermal actuators. The devices were made by a single mask process using electroplated Ni as the active material. Tests showed that the metal based thermal actuators deliver a maximum displacement of ~20µm at a much lower temperature than that of Si-based actuators. However Ni-actuators showed a severe back bending, which increases with increasing applied power. The temperature to initiate the back bending is as low as ~240°C. Back bending increases the distance between the two actuators, and leads to locking function failure. For practical application, Ni-based thermal actuators must be operated below 200°C.

Polypyrrole Actuators for Tremor Suppression

DEFF Research Database (Denmark)

Skaarup, Steen; Mogensen, Naja; Bay, Lasse

2003-01-01

Neurological tremor affecting limbs can be divided into at least 6 different types with frequencies ranging from 2 to about 20 Hz. In order to alleviate the symptoms by suppressing the tremor, sensing and actuation systems able to perform at these frequencies are needed. Electroactive polymers...... exemplify 'soft actuator' technology that may be especially suitable for use in conjunction with human limbs. The electrochemical and mechanical properties of polypyrrole dodecyl benzene sulphonate actuator films have been studied with this application in mind. The results show that the time constants...

Integration of fluidic jet actuators in composite structures

Science.gov (United States)

Schueller, Martin; Lipowski, Mathias; Schirmer, Eckart; Walther, Marco; Otto, Thomas; Geßner, Thomas; Kroll, Lothar

2015-04-01

Fluidic Actuated Flow Control (FAFC) has been introduced as a technology that influences the boundary layer by actively blowing air through slots or holes in the aircraft skin or wind turbine rotor blade. Modern wing structures are or will be manufactured using composite materials. In these state of the art systems, AFC actuators are integrated in a hybrid approach. The new idea is to directly integrate the active fluidic elements (such as SJAs and PJAs) and their components in the structure of the airfoil. Consequently, the integration of such fluidic devices must fit the manufacturing process and the material properties of the composite structure. The challenge is to integrate temperature-sensitive active elements and to realize fluidic cavities at the same time. The transducer elements will be provided for the manufacturing steps using roll-to-roll processes. The fluidic parts of the actuators will be manufactured using the MuCell® process that provides on the one hand the defined reproduction of the fluidic structures and, on the other hand, a high light weight index. Based on the first design concept, a demonstrator was developed in order to proof the design approach. The output velocity on the exit was measured using a hot-wire anemometer.

Design of a linear-motion dual-stage actuation system for precision control

International Nuclear Information System (INIS)

Dong, W; Tang, J; ElDeeb, Y

2009-01-01

Actuators with high linear-motion speed, high positioning resolution and a long motion stroke are needed in many precision machining systems. In some current systems, voice coil motors (VCMs) are implemented for servo control. While the voice coil motors may provide the long motion stroke needed in many applications, the main obstacle that hinders the improvement of the machining accuracy and efficiency is their limited bandwidth. To fundamentally solve this issue, we propose to develop a dual-stage actuation system that consists of a voice coil motor that covers the coarse motion, and a piezoelectric stack actuator that induces the fine motion, thus enhancing the positioning accuracy. The focus of this present research is the mechatronics design and synthesis of the new actuation system. In particular, a flexure hinge based mechanism is developed to provide a motion guide and preload to the piezoelectric stack actuator that is serially connected to the voice coil motor. This mechanism is built upon parallel plane flexure hinges. A series of numerical and experimental studies are carried out to facilitate the system design and the model identification. The effectiveness of the proposed system is demonstrated through open-loop studies and preliminary closed-loop control practice. While the primary goal of this particular design is aimed at enhancing optical lens machining, the concept and approach outlined are generic and can be extended to a variety of applications

Universal and inductorless DC/DC converter for multi-output power supplies in sensor and actuator networks

Science.gov (United States)

Saponara, Sergio; Ciarpi, Gabriele

2017-05-01

This work proposes a universal and inductorless DC/DC converter that can be used for a wide input range, from few V to 60 V, to regulate output voltages from 5 V down to 1 V in Sensor and Actuator Network nodes. The proposed converter has been developed within the Athenis3D European project. It is composed by a cascade of multiple switching capacitor stages, with a proper skip-mode control to implement both step-down and step-up converting ratios, thus regulating all input sources to a voltage of about 6 V. These switching stages are further cascaded with linear regulators, which can provide stable output voltages down to 1 V. The multi-output regulator has been realized as a single-chip in a low-cost 0.35 μm CMOS technology. It is available as a naked die or in a ceramic package. The only needed external components are surface mount capacitors, which can be integrated on top of the naked chip die, creating a 3D structure, using trench capacitors embedded in a passive interposing layer. This way the size of the power management unit is further minimized. An advantage of the proposed converter is that it isn't optimized for a particular input voltage, therefore it can be used with no constant input power, like power harvesting systems (e.g. solar cells, wind and water turbines) and very disturbed power supplies.

Study of damping in 5 kWh superconductor flywheel energy storage system using a piezoelectric actuator

Energy Technology Data Exchange (ETDEWEB)

Jang, H.K.; Song, D.; Kim, S.B. [Hanyang University, 17 Haengdang-Dong, Seongdong-Gu, Seoul 133-791 (Korea, Republic of); Han, S.C. [Korea Electric Power Research Institute, 103-16 Munji-Ro, Yuseong-Gu, Daejeon 305-380 (Korea, Republic of); Sung, T.H., E-mail: sungth@hanyang.ac.kr [Hanyang University, 17 Haengdang-Dong, Seongdong-Gu, Seoul 133-791 (Korea, Republic of)

2012-05-15

A 5 kWh superconductor flywheel energy storage system (SFES) has advantages in terms of high electrical energy density, environmental affinity and long life. However, the SFES has disadvantage that electromagnetic damper is needed because superconducting bearings do not have enough damping coefficient. The purpose of this experiment is to develop a method of damping the vibration of the SFES. A piezoelectric actuator was attached to a superconducting bearing system for feasibility test in order to make it as a damper of the SFES. For this experiment, a cylindrical permanent magnet (PM) 40 mm in diameter and 10 mm height was used as a rotor, a high-temperature superconductor bulk (HTS bulk) with dimensions 40 mm Multiplication-Sign 40 mm Multiplication-Sign 15 mm was used as a stator, and two vibration exciters (an upper and a lower vibration exciter) and a piezoelectric actuator were used. The PM was fixed on the upper vibration exciter. The HTS bulk was fixed on either the lower vibration exciter to test for damping in the feasibility test, or on the piezoelectric actuator for the actual SFES. The conditions of this experiment included various voltage outputs of a power amplifier to the lower vibration exciter, moving distances of the piezoelectric actuator which are displacements of the HTS bulk, and phase differences between the upper and lower vibration exciter or the piezoelectric actuator. The damping feasibility test was conducted with a 300 {mu}m gap between the PM and HTS bulk with a PM vibration of 30 {mu}m. For the actual SFES test, the gap between the PM and HTS bulk was 1.6 mm and the PM vibration was 25 {mu}m. The following conditions were conducted to optimize: an appropriate voltage input to the lower vibration exciter or a displacement of piezoelectric actuator and an appropriate phase difference. When the piezoelectric actuator was used, the damping effect was greatly improved up to 92.32% which a displacement of damped PM was 1.92 {mu}m.

Mechatronics and Bioinspiration in Actuator Design and Control

Directory of Open Access Journals (Sweden)

J. L. Pons

2008-01-01

Full Text Available Actuators are components of motion control systems in which mechatronics plays a crucial role. They can be regarded as a paradigmatic case in which this mechatronic approach is required. Furthermore, actuator technologies can get new sources of inspiration from nature (bioinspiration. Biological systems are the result of an evolutionary process and show excellent levels of performance. In this paper, we analyse the actuator as a bioinspired mechatronic system through analogies between mechatronics and biological actuating mechanisms that include hierarchical control of actuators, switched control of power flow and some transduction principles. Firstly, some biological models are introduced as a source of inspiration for setting up both actuation principles and control technologies. Secondly, a particular actuator technology, the travelling wave ultrasonic motor, is taken to illustrate this approach. Eventually, the last section draws some conclusions and points out future directions.

Performance Comparison of Sweeping/Steady Jet Actuators

Science.gov (United States)

Hirsch, Damian; Mercier, Justin; Noca, Flavio; Gharib, Morteza

2015-11-01

Flow control through the use of steady jet actuators has been used on various aircraft models since the late 1950's. However, the focus of recent studies has shifted towards the use of sweeping jets (fluidic oscillators) rather than steady jet actuators. In this work, experiments using various jet actuator designs were conducted at GALCIT's Lucas Wind Tunnel on a NACA 0012 vertical tail model similar to that of the Boeing 767 vertical stabilizer at Reynolds numbers ranging from 0.5 to 1.2 million. The rudder angle was fixed at 20 degrees. A total of 32 jet actuators were installed along the wingspan perpendicular to the trailing edge and the rudder shoulder of the vertical stabilizer. It is known that these types of flow control prevent separation. However, the goal of this work is to compare different jet designs and evaluate their performance. Parameters such as the number of actuators, their volumetric flow, and the wind tunnel speed were varied. The lift generation capabilities of steady and sweeping jet actuators were then compared. Another set of experiments was conducted to compare a new sweeping jet actuator design with one of the standard versions. Supported by Boeing.

Modeling and control of a self-sensing polymer metal composite actuator

International Nuclear Information System (INIS)

Nam, Doan Ngoc Chi; Ahn, Kyoung Kwan

2014-01-01

An ion polymer metal composite (IPMC) is an electro-active polymer (EAP) that bends in response to a small applied electrical field as a result of mobility of cations in the polymer network and vice versa. One drawback in the use of an IPMC is the sensing problem for such a small size actuator. The aim of this paper is to develop a physical model for a self-sensing IPMC actuator and to verify its applicability for practical position control. Firstly, ion dynamics inside a polymer membrane is investigated with an asymmetric solution in the presence of distributed surface resistance. Based on this analysis, a modified equivalent circuit and a simple configuration to realize the self-sensing IPMC actuator are proposed. Mathematical modelling and experimental evaluation indicate that the bending curvature can be obtained accurately using several feedback voltage signals along with the IPMC length. Finally, the controllability of the developed self-sensing IPMC actuator is investigated using a robust position control. Experimental results prove that the self-sensing characteristics can be applied in engineering control problems to provide a more convenient sensing method for IPMC actuating systems. (paper)

Dielectric elastomer actuators used for pneumatic valve technology

International Nuclear Information System (INIS)

Giousouf, Metin; Kovacs, Gabor

2013-01-01

Dielectric elastomer actuators have been investigated for applications in the field of pneumatic automation technology. We have developed different valve designs with stacked dielectric elastomer actuators and with integrated high voltage converters. The actuators were made using VHB-4910 material and a stacker machine for automated fabrication of the cylindrical actuators. Typical characteristics of pneumatic valves such as flow rate, power consumption and dynamic behaviour are presented. For valve construction the force and stroke parameters of the dielectric elastomer actuator have been measured. Further, benefits for valve applications using dielectric elastomers are shown as well as their potential operational area. Finally, challenges are discussed that are relevant for the use of elastomer actuators in valves for industrial applications. (paper)

14 CFR 33.72 - Hydraulic actuating systems.

Science.gov (United States)

2010-01-01

... AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Design and Construction; Turbine Aircraft Engines § 33.72 Hydraulic actuating systems. Each hydraulic actuating system must function properly under all conditions in which the... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Hydraulic actuating systems. 33.72 Section...

Exact analysis of two kinds of piezoelectric actuator

International Nuclear Information System (INIS)

Han Rong; Shi Zhifei

2008-01-01

Two kinds of piezoelectric hollow cylinder actuator are studied in this paper. One is the expansion actuator and the other is the contraction actuator. Using the Airy stress function method, the analytical solutions of these two kinds of actuators are obtained based on the theory of piezo-elasticity. The solutions are compared with numerical results and good agreement is found. Inherent properties of these two kinds of piezoelectric cylinder actuator are presented and discussed. Findings have applications in the field of micromechanics and microengineering

Sliding mode control for uncertain unified chaotic systems with input nonlinearity

International Nuclear Information System (INIS)

Chiang, T.-Y.; Hung, M.-L.; Yan, J.-J.; Yang, Y.-S.; Chang, J.-F.

2007-01-01

This paper investigates the stabilization problem for a class of unified chaotic systems subject to uncertainties and input nonlinearity. Using the sliding mode control technique, a robust control law is established which stabilizes the uncertain unified chaotic systems even when the nonlinearity in the actuators is present. A novel adaptive switching surface is introduced to simplify the task of assigning the stability of the closed-loop system in the sliding mode motion. An illustrative example is given to demonstrate the effectiveness of the proposed sliding mode control design

Networked Rectenna Array for Smart Material Actuators

Science.gov (United States)

Choi, Sang H.; Golembiewski, Walter T.; Song, Kyo D.

2000-01-01

The concept of microwave-driven smart material actuators is envisioned as the best option to alleviate the complexity associated with hard-wired control circuitry. Networked rectenna patch array receives and converts microwave power into a DC power for an array of smart actuators. To use microwave power effectively, the concept of a power allocation and distribution (PAD) circuit is adopted for networking a rectenna/actuator patch array. The PAD circuit is imbedded into a single embodiment of rectenna and actuator array. The thin-film microcircuit embodiment of PAD circuit adds insignificant amount of rigidity to membrane flexibility. Preliminary design and fabrication of PAD circuitry that consists of a few nodal elements were made for laboratory testing. The networked actuators were tested to correlate the network coupling effect, power allocation and distribution, and response time. The features of preliminary design are 16-channel computer control of actuators by a PCI board and the compensator for a power failure or leakage of one or more rectennas.

A New and Versatile Adjustable Rigidity Actuator with Add-on Locking Mechanism (ARES-XL

Directory of Open Access Journals (Sweden)

Manuel Cestari

2018-01-01

Full Text Available Adjustable compliant actuators are being designed and implemented in robotic devices because of their ability to minimize large forces due to impacts, to safely interact with the user, and to store and release energy in passive elastic elements. Conceived as a new force-controlled compliant actuator, an adjustable rigidity with embedded sensor and locking mechanism actuator (ARES-XL is presented in this paper. This compliant system is intended to be implemented in a gait exoskeleton for children with neuro muscular diseases (NMDs to exploit the intrinsic dynamics during locomotion. This paper describes the mechanics and initial evaluation of the ARES-XL, a novel variable impedance actuator (VIA that allows the implementation of an add-on locking mechanism to this system, and in combination with its zero stiffness capability and large deflection range, provides this novel joint with improved properties when compared to previous prototypes developed by the authors and other state-of-the-art (SoA devices. The evaluation of the system proves how this design exceeds the main capabilities of a previous prototype as well as providing versatile actuation that could lead to its implementation in multiple joints.

Design and performance analysis of position-based impedance control for an electrohydrostatic actuation system

Directory of Open Access Journals (Sweden)

Yongling FU

2018-03-01

Full Text Available Electrohydrostatic actuator (EHA is a type of power-by-wire actuator that is widely implemented in the aerospace industry for flight control, landing gears, thrust reversers, thrust vector control, and space robots. This paper presents the development and evaluation of position-based impedance control (PBIC for an EHA. Impedance control provides the actuator with compliance and facilitates the interaction with the environment. Most impedance control applications utilize electrical or valve-controlled hydraulic actuators, whereas this work realizes impedance control via a compact and efficient EHA. The structures of the EHA and PBIC are firstly introduced. A mathematical model of the actuation system is established, and values of its coefficients are identified by particle swarm optimization. This model facilitates the development of a position controller and the selection of target impedance parameters. A nonlinear proportional-integral position controller is developed for the EHA to achieve the accurate positioning requirement of PBIC. The controller compensates for the adverse effect of stiction, and a position accuracy of 0.08 mm is attained. Various experimental results are presented to verify the applicability of PBIC to the EHA. The compliance of the actuator is demonstrated in an impact test. Keywords: Actuation system, Aerospace, Electrohydrostatic actuator, Force control, Nonlinear dynamics, Particle swarm optimization, Position control

Model-based design and experimental verification of a monitoring concept for an active-active electromechanical aileron actuation system

Science.gov (United States)

Arriola, David; Thielecke, Frank

2017-09-01

Electromechanical actuators have become a key technology for the onset of power-by-wire flight control systems in the next generation of commercial aircraft. The design of robust control and monitoring functions for these devices capable to mitigate the effects of safety-critical faults is essential in order to achieve the required level of fault tolerance. A primary flight control system comprising two electromechanical actuators nominally operating in active-active mode is considered. A set of five signal-based monitoring functions are designed using a detailed model of the system under consideration which includes non-linear parasitic effects, measurement and data acquisition effects, and actuator faults. Robust detection thresholds are determined based on the analysis of parametric and input uncertainties. The designed monitoring functions are verified experimentally and by simulation through the injection of faults in the validated model and in a test-rig suited to the actuation system under consideration, respectively. They guarantee a robust and efficient fault detection and isolation with a low risk of false alarms, additionally enabling the correct reconfiguration of the system for an enhanced operational availability. In 98% of the performed experiments and simulations, the correct faults were detected and confirmed within the time objectives set.

Engineering Design Tools for Shape Memory Alloy Actuators: CASMART Collaborative Best Practices and Case Studies

Science.gov (United States)

Wheeler, Robert W.; Benafan, Othmane; Gao, Xiujie; Calkins, Frederick T; Ghanbari, Zahra; Hommer, Garrison; Lagoudas, Dimitris; Petersen, Andrew; Pless, Jennifer M.; Stebner, Aaron P.;

The Actuated Guitar

DEFF Research Database (Denmark)

Larsen, Jeppe Veirum; Overholt, Daniel; Moeslund, Thomas B.

2013-01-01

Playing a guitar is normally only for people with fully functional hands. In this work we investigate alternative interaction concepts to enable or re-enable people with non-functional right hands or arms to play a guitar via actuated strumming. The functionality and complexity of right hand...... interaction with the guitar is immense. We therefore divided the right hand techniques into three main areas: Strumming, string picking / skipping, and string muting. This paper explores the first stage, strum- ming. We have developed an exploratory platform called the Actuated Guitar that utilizes a normal...

Honeycomb Actuators Inspired by the Unfolding of Ice Plant Seed Capsules.

Directory of Open Access Journals (Sweden)

Lorenzo Guiducci

Full Text Available Plant hydro-actuated systems provide a rich source of inspiration for designing autonomously morphing devices. One such example, the pentagonal ice plant seed capsule, achieves complex mechanical actuation which is critically dependent on its hierarchical organization. The functional core of this actuation system involves the controlled expansion of a highly swellable cellulosic layer, which is surrounded by a non-swellable honeycomb framework. In this work, we extract the design principles behind the unfolding of the ice plant seed capsules, and use two different approaches to develop autonomously deforming honeycomb devices as a proof of concept. By combining swelling experiments with analytical and finite element modelling, we elucidate the role of each design parameter on the actuation of the prototypes. Through these approaches, we demonstrate potential pathways to design/develop/construct autonomously morphing systems by tailoring and amplifying the initial material's response to external stimuli through simple geometric design of the system at two different length scales.

Dynamic Actuation of Single-Crystal Diamond Nanobeams

OpenAIRE

Sohn, Young-Ik; Burek, Michael J.; Kara, Vural; Kearns, Ryan; Lončar, Marko

2014-01-01

We show the dielectrophoretic actuation of single-crystal diamond nanomechanical devices. Gradient radio-frequency electromagnetic forces are used to achieve actuation of both cantilever and doubly clamped beam structures, with operation frequencies ranging from a few MHz to ~50MHz. Frequency tuning and parametric actuation are also studied.

35 Hz shape memory alloy actuator with bending-twisting mode

Science.gov (United States)

Song, Sung-Hyuk; Lee, Jang-Yeob; Rodrigue, Hugo; Choi, Ik-Seong; Kang, Yeon June; Ahn, Sung-Hoon

2016-01-01

Shape Memory Alloy (SMA) materials are widely used as an actuating source for bending actuators due to their high power density. However, due to the slow actuation speed of SMAs, there are limitations in their range of possible applications. This paper proposes a smart soft composite (SSC) actuator capable of fast bending actuation with large deformations. To increase the actuation speed of SMA actuator, multiple thin SMA wires are used to increase the heat dissipation for faster cooling. The actuation characteristics of the actuator at different frequencies are measured with different actuator lengths and results show that resonance can be used to realize large deformations up to 35 Hz. The actuation characteristics of the actuator can be modified by changing the design of the layered reinforcement structure embedded in the actuator, thus the natural frequency and length of an actuator can be optimized for a specific actuation speed. A model is used to compare with the experimental results of actuators with different layered reinforcement structure designs. Also, a bend-twist coupled motion using an anisotropic layered reinforcement structure at a speed of 10 Hz is also realized. By increasing their range of actuation characteristics, the proposed actuator extends the range of application of SMA bending actuators. PMID:26892438

Miniature Low-Mass Drill Actuated by Flextensional Piezo Stack

Science.gov (United States)

Sherrit, Stewart; Badescu, Mircea; Bar-Cohen, Yoseph

2010-01-01

Recent experiments with a flextensional piezoelectric actuator have led to the development of a sampler with a bit that is designed to produce and capture a full set of sample forms including volatiles, powdered cuttings, and core fragments. The flextensional piezoelectric actuator is a part of a series of devices used to amplify the generated strain from piezoelectric actuators. Other examples include stacks, bimorphs, benders, and cantilevers. These devices combine geometric and resonance amplifications to produce large stroke at high power density. The operation of this sampler/drill was demonstrated using a 3x2x1-cm actuator weighing 12 g using power of about 10-W and a preload of about 10 N. A limestone block was drilled to a depth of about 1 cm in five minutes to produce powdered cuttings. It is generally hard to collect volatiles from random surface profiles found in rocks and sediment, powdered cuttings, and core fragments. Toward the end of collecting volatiles, the actuator and the bit are covered with bellows-shaped shrouds to prevent fines and other debris from reaching the analyzer. A tube with a miniature bellows (to provide flexibility) is connected to the bit and directs the flow of the volatiles to the analyzer. Another modality was conceived where the hose is connected to the bellows wall directly to allow the capture of volatiles generated both inside and outside the bit. A wide variety of commercial bellows used in the vacuum and microwave industries can be used to design the volatiles capture mechanism. The piezoelectric drilling mechanism can potentially be operated in a broad temperature range from about-200 to less than 450 C. The actuators used here are similar to the actuators that are currently baselined to fly as part of the inlet funnel shaking mechanism design of MSL (Mars Science Laboratory). The space qualification of these parts gives this drill a higher potential for inclusion in a future mission, especially when considering its

A finite element model of rigid body structures actuated by dielectric elastomer actuators

Science.gov (United States)

Simone, F.; Linnebach, P.; Rizzello, G.; Seelecke, S.

2018-06-01

This paper presents on finite element (FE) modeling and simulation of dielectric elastomer actuators (DEAs) coupled with articulated structures. DEAs have proven to represent an effective transduction technology for the realization of large deformation, low-power consuming, and fast mechatronic actuators. However, the complex dynamic behavior of the material, characterized by nonlinearities and rate-dependent phenomena, makes it difficult to accurately model and design DEA systems. The problem is further complicated in case the DEA is used to activate articulated structures, which increase both system complexity and implementation effort of numerical simulation models. In this paper, we present a model based tool which allows to effectively implement and simulate complex articulated systems actuated by DEAs. A first prototype of a compact switch actuated by DEA membranes is chosen as reference study to introduce the methodology. The commercially available FE software COMSOL is used for implementing and coupling a physics-based dynamic model of the DEA with the external structure, i.e., the switch. The model is then experimentally calibrated and validated in both quasi-static and dynamic loading conditions. Finally, preliminary results on how to use the simulation tool to optimize the design are presented.

A novel multi-actuation CMOS RF MEMS switch

Science.gov (United States)

Lee, Chiung-I.; Ko, Chih-Hsiang; Huang, Tsun-Che

2008-12-01

This paper demonstrates a capacitive shunt type RF MEMS switch, which is actuated by electro-thermal actuator and electrostatic actuator at the same time, and than latching the switching status by electrostatic force only. Since thermal actuators need relative low voltage compare to electrostatic actuators, and electrostatic force needs almost no power to maintain the switching status, the benefits of the mechanism are very low actuation voltage and low power consumption. Moreover, the RF MEMS switch has considered issues for integrated circuit compatible in design phase. So the switch is fabricated by a standard 0.35um 2P4M CMOS process and uses wet etching and dry etching technologies for postprocess. This compatible ability is important because the RF characteristics are not only related to the device itself. If a packaged RF switch and a packaged IC wired together, the parasitic capacitance will cause the problem for optimization. The structure of the switch consists of a set of CPW transmission lines and a suspended membrane. The CPW lines and the membrane are in metal layers of CMOS process. Besides, the electro-thermal actuators are designed by polysilicon layer of the CMOS process. So the RF switch is only CMOS process layers needed for both electro-thermal and electrostatic actuations in switch. The thermal actuator is composed of a three-dimensional membrane and two heaters. The membrane is a stacked step structure including two metal layers in CMOS process, and heat is generated by poly silicon resistors near the anchors of membrane. Measured results show that the actuation voltage of the switch is under 7V for electro-thermal added electrostatic actuation.

Assistive acting movement therapy devices with pneumatic rotary-type soft actuators.

Science.gov (United States)

Wilkening, André; Baiden, David; Ivlev, Oleg

2012-12-01

Inherent compliance and assistive behavior are assumed to be essential properties for safe human-robot interaction. Rehabilitation robots demand the highest standards in this respect because the machine interacts directly with weak persons who are often sensitive to pain. Using novel soft fluidic actuators with rotary elastic chambers (REC actuators), compact, lightweight, and cost-effective therapeutic devices can be developed. This article describes modular design and control strategies for new assistive acting robotic devices for upper and lower extremities. Due to the inherent compliance and natural back-drivability of pneumatic REC actuators, these movement therapy devices provide gentle treatment, whereby the interaction forces between humans and the therapy device are estimated without the use of expensive force/torque sensors. An active model-based gravity compensation based on separated models of the robot and of the individual patient's extremity provides the basis for effective assistive control. The utilization of pneumatic actuators demands a special safety concept, which is merged with control algorithms to provide a sufficient level of safeness and to catch any possible system errors and/or emergency situations. A self-explanatory user interface allows for easy, intuitive handling. Prototypes are very comfortable for use due to several control routines that work in the background. Assistive devices have been tested extensively with several healthy persons; the knee/hip movement therapy device is now under clinical trials at the Clinic for Orthopaedics and Trauma Surgery at the Klinikum Stuttgart.

Vibrotactile using micromachined electromagnetic actuators array

International Nuclear Information System (INIS)

Talbi, A; Ducloux, O; Tiercelin, N; Deblock, Y; Pernod, P; Preobrazhensky, V

2006-01-01

One motivating application of this technology is the development of a tactile display interface, where discrete mechanical actuators apply vibratory excitation at discrete locations on the skin. Specifically, this paper describes the development fabrication and characterization of a 4 x 4 micro-actuator array of vibrating pixels for fingertip tactile communication. The vibrting pixels are generated by using an electromagnetic microresonator. The fabrication sequence and the actuation performance of the array are also presented

Nonmagnetic driver for piezoelectric actuators

DEFF Research Database (Denmark)

Ekhtiari, Marzieh

2014-01-01

actuator drive is the only form-fit continuous drive solution currently available for the development of high performance nonmagnetic motors. In this research focus will be on the non magnetic compact high efficiency driver for the piezo actuators and on employing energy recovery from the capacitive...

Design, analysis and testing of a new piezoelectric tool actuator for elliptical vibration turning

Science.gov (United States)

Lin, Jieqiong; Han, Jinguo; Lu, Mingming; Yu, Baojun; Gu, Yan

2017-08-01

A new piezoelectric tool actuator (PETA) for elliptical vibration turning has been developed based on a hybrid flexure hinge connection. Two double parallel four-bar linkage mechanisms and two right circular flexure hinges were chosen to guide the motion. The two input displacement directional stiffness were modeled according to the principle of virtual work modeling method and the kinematic analysis was conducted theoretically. Finite element analysis was used to carry out static and dynamic analyses. To evaluate the performance of the developed PETA, off-line experimental tests were carried out to investigate the step responses, motion strokes, resolutions, parasitic motions, and natural frequencies of the PETA along the two input directions. The relationship between input displacement and output displacement, as well as the tool tip’s elliptical trajectory in different phase shifts was analyzed. By using the developed PETA mechanism, micro-dimple patterns were generated as the preliminary application to demonstrate the feasibility and efficiency of PETA for elliptical vibration turning.

Control Demonstration of a Thin Deformable In-Plane Actuated Mirror

Science.gov (United States)

2006-03-01

36 20. Influence Function of Actuator One . . . . . . . . . . . . . . . . . . . . . . . . 37 21. Influence Function of Actuator Two...38 22. Influence Function of Actuator Three . . . . . . . . . . . . . . . . . . . . . . . 38 23. Influence ... Function of Actuator Four . . . . . . . . . . . . . . . . . . . . . . . . 39 24. Influence Function of Actuator Five

Active Vibration Isolation Devices with Inertial Servo Actuators

Science.gov (United States)

Melik-Shakhnazarov, V. A.; Strelov, V. I.; Sofiyanchuk, D. V.; Tregubenko, A. A.

2018-03-01

The use of active vibration isolation devices (AVIDs) in aerospace engineering is subject to the following restrictions. First, the volume for installing additional devices is always limited in instrument racks and compartments. Secondly, in many cases, it is impossible to add supports for servo actuators for fundamental or design considerations. In the paper, it has been shown that this problem can be solved if the inertial servo actuators are used in AVIDs instead of reference actuators. A transfer function has been theoretically calculated for an AVID controlled by inertial actuators. It has been shown that the volume of a six-mode single-housing AVID with inertial actuators can be 2-2.5 times smaller than that of devices with support actuators.

Devising Mobile Sensing and Actuation Infrastructure with Drones

Directory of Open Access Journals (Sweden)

Mungyu Bae

2018-02-01

Full Text Available Vast applications and services have been enabled as the number of mobile or sensing devices with communication capabilities has grown. However, managing the devices, integrating networks or combining services across different networks has become a new problem since each network is not directly connected via back-end core networks or servers. The issue is and has been discussed especially in wireless sensor and actuator networks (WSAN. In such systems, sensors and actuators are tightly coupled, so when an independent WSAN needs to collaborate with other networks, it is difficult to adequately combine them into an integrated infrastructure. In this paper, we propose drone-as-a-gateway (DaaG, which uses drones as mobile gateways to interconnect isolated networks or combine independent services. Our system contains features that focus on the service being provided in the order of importance, different from an adaptive simple mobile sink system or delay-tolerant system. Our simulation results have shown that the proposed system is able to activate actuators in the order of importance of the service, which uses separate sensors’ data, and it consumes almost the same time in comparison with other path-planning algorithms. Moreover, we have implemented DaaG and presented results in a field test to show that it can enable large-scale on-demand deployment of sensing and actuation infrastructure or the Internet of Things (IoT.

Devising Mobile Sensing and Actuation Infrastructure with Drones

Science.gov (United States)

Jung, Jongtack; Park, Seongjoon; Kim, Kangho; Lee, Joon Yeop

2018-01-01

Vast applications and services have been enabled as the number of mobile or sensing devices with communication capabilities has grown. However, managing the devices, integrating networks or combining services across different networks has become a new problem since each network is not directly connected via back-end core networks or servers. The issue is and has been discussed especially in wireless sensor and actuator networks (WSAN). In such systems, sensors and actuators are tightly coupled, so when an independent WSAN needs to collaborate with other networks, it is difficult to adequately combine them into an integrated infrastructure. In this paper, we propose drone-as-a-gateway (DaaG), which uses drones as mobile gateways to interconnect isolated networks or combine independent services. Our system contains features that focus on the service being provided in the order of importance, different from an adaptive simple mobile sink system or delay-tolerant system. Our simulation results have shown that the proposed system is able to activate actuators in the order of importance of the service, which uses separate sensors’ data, and it consumes almost the same time in comparison with other path-planning algorithms. Moreover, we have implemented DaaG and presented results in a field test to show that it can enable large-scale on-demand deployment of sensing and actuation infrastructure or the Internet of Things (IoT). PMID:29463064

Devising Mobile Sensing and Actuation Infrastructure with Drones.

Science.gov (United States)

Bae, Mungyu; Yoo, Seungho; Jung, Jongtack; Park, Seongjoon; Kim, Kangho; Kim, Joon Yeop Lee; Kim, Hwangnam

2018-02-19

Vast applications and services have been enabled as the number of mobile or sensing devices with communication capabilities has grown. However, managing the devices, integrating networks or combining services across different networks has become a new problem since each network is not directly connected via back-end core networks or servers. The issue is and has been discussed especially in wireless sensor and actuator networks (WSAN). In such systems, sensors and actuators are tightly coupled, so when an independent WSAN needs to collaborate with other networks, it is difficult to adequately combine them into an integrated infrastructure. In this paper, we propose drone-as-a-gateway (DaaG), which uses drones as mobile gateways to interconnect isolated networks or combine independent services. Our system contains features that focus on the service being provided in the order of importance, different from an adaptive simple mobile sink system or delay-tolerant system. Our simulation results have shown that the proposed system is able to activate actuators in the order of importance of the service, which uses separate sensors' data, and it consumes almost the same time in comparison with other path-planning algorithms. Moreover, we have implemented DaaG and presented results in a field test to show that it can enable large-scale on-demand deployment of sensing and actuation infrastructure or the Internet of Things (IoT).

Vertical Tail Buffeting Alleviation Using Piezoelectric Actuators-Some Results of the Actively Controlled Response of Buffet-Affected Tails (ACROBAT) Program

Science.gov (United States)

Moses, Robert W.

1997-01-01

Buffet is an aeroelastic phenomenon associated with high performance aircraft especially those with twin vertical tails. In particular, for the F/A-18 aircraft at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their wake. The resulting buffet loads on the vertical tails are a concern from fatigue and inspection points of view. Recently, a 1/6-scale F-18 wind-tunnel model was tested in the Transonic Dynamics Tunnel at the NASA Langley Research Center as part of the Actively Controlled Response Of Buffet Affected Tails (ACROBAT) Program to assess the use of active controls in reducing vertical tail buffeting. The starboard vertical tail was equipped with an active rudder and the port vertical tail was equipped with piezoelectric actuators. The tunnel conditions were atmospheric air at Mach 0.10. By using single-input-single-output control laws at gains well below the physical limits of the actuators, the power spectral density of the root strains at the frequency of the first bending mode of the vertical tail was reduced by as much as 60 percent up to angles of attack of 37 degrees. Root mean square (RMS) values of root strain were reduced by as much as 19 percent. The results herein illustrate that buffet alleviation of vertical tails can be accomplished using simple active control of the rudder or piezoelectric actuators. In fact, as demonstrated herein, a fixed gain single input single output control law that commands piezoelectric actuators may be active throughout the high angle-of-attack maneuver without requiring any changes during the maneuver. Future tests are mentioned for accentuating the international interest in this area of research.

Characterization of high speed synthetic jet actuators

Science.gov (United States)

Pikcilingis, Lucia

Over the last 20 years, synthetic jets have been studied as a means for aerodynamic active flow control. Specifically, synthetic jets provide momentum transfer with zero-net mass flux, which has been proven to be effective for controlling flow fields. A synthetic jet is created by the periodic formation of vortex rings at its orifice due to the periodic motion of a piezoelectric disk(s). The present study seeks to optimize the performance of a synthetic jet actuator by utilizing different geometrical parameters such as disk thickness, orifice width and length, cavity height and cavity diameter, and different input parameters such as driving voltage and frequency. Two apparatuses were used with a cavity diameter of either 80 mm or 160 mm. Piezoelectric-based disks were provided by the Mide Corporation. Experiments were conducted using several synthetic jet apparatuses designed for various geometrical parameters utilizing a dual disk configuration. Velocity and temperature measurements were acquired at the center of the synthetic jet orifice using a temperature compensated hotwire and thermocouple probe. The disk(s) displacement was measured at the center of the disk with a laser displacement sensor. It was shown that the synthetic jets, having the 80 mm cavity diameter, are capable of exceeding peak velocities of 200 m/s with a relatively large orifice of dimensions AR = 12, hc* = 3, and hn* = 4. In addition, the conditions at which the disks were manufactured had minimal effect on the performance of the jet, except for the pair with overnight resting time as opposed to less than an hour resting time for the control units. Altering the tab style of the disks, where the tab allows the electrical circuit to be exposed for external power connection, showed that a thin fragile tab versus a tab of the same thickness as the disk has minimal effect on the performance but affects the durability of the disk due to the fragility or robustness of the tab. The synthetic jets

Electromagnetic actuation in MEMS switches

DEFF Research Database (Denmark)

Oliveira Hansen, Roana Melina de; Mátéfi-Tempfli, Mária; Chemnitz, Steffen

. Electromagnetic actuation is a very promising approach to operate such MEMS and Power MEMS devices, due to the long range, reproducible and strong forces generated by this method, among other advantages. However, the use of electromagnetic actuation in such devices requires the use of thick magnetic films, which...

Toward a New Generation of Smart Biomimetic Actuators for Architecture.

Science.gov (United States)

Poppinga, Simon; Zollfrank, Cordt; Prucker, Oswald; Rühe, Jürgen; Menges, Achim; Cheng, Tiffany; Speck, Thomas

2017-10-24

Motile plant structures (e.g., leaves, petals, cone scales, and capsules) are functionally highly robust and resilient concept generators for the development of biomimetic actuators for architecture. Here, a concise review of the state-of-the-art of plant movement principles and derived biomimetic devices is provided. Achieving complex and higher-dimensional shape changes and passive-hydraulic actuation at a considerable time scale, as well as mechanical robustness of the motile technical structures, is challenging. For example, almost all currently available bioinspired hydraulic actuators show similar limitations due to the poroelastic time scale. Therefore, a major challenge is increasing the system size to the meter range, with actuation times of minutes or below. This means that response speed and flow rate need significant improvement for the systems, and the long-term performance degradation issue of hygroscopic materials needs to be addressed. A theoretical concept for "escaping" the poroelastic regime is proposed, and the possibilities for enhancing the mechanical properties of passive-hydraulic bilayer actuators are discussed. Furthermore, the promising aspects for further studies to implement tropistic movement behavior are presented, i.e., movement that depends on the direction of the triggering stimulus, which can finally lead to "smart building skins" that autonomously and self-sufficiently react to changing environmental stimuli in a direction-dependent manner. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A methodology for identification and control of electro-mechanical actuators.

Science.gov (United States)

Tutunji, Tarek A; Saleem, Ashraf

2015-01-01

Mechatronic systems are fully-integrated engineering systems that are composed of mechanical, electronic, and computer control sub-systems. These integrated systems use electro-mechanical actuators to cause the required motion. Therefore, the design of appropriate controllers for these actuators are an essential step in mechatronic system design. In this paper, a three-stage methodology for real-time identification and control of electro-mechanical actuator plants is presented, tested, and validated. First, identification models are constructed from experimental data to approximate the plants' response. Second, the identified model is used in a simulation environment for the purpose of designing a suitable controller. Finally, the designed controller is applied and tested on the real plant through Hardware-in-the-Loop (HIL) environment. The described three-stage methodology provides the following practical contributions: •Establishes an easy-to-follow methodology for controller design of electro-mechanical actuators.•Combines off-line and on-line controller design for practical performance.•Modifies the HIL concept by using physical plants with computer control (rather than virtual plants with physical controllers). Simulated and experimental results for two case studies, induction motor and vehicle drive system, are presented in order to validate the proposed methodology. These results showed that electromechanical actuators can be identified and controlled using an easy-to-duplicate and flexible procedure.

Another Lesson from Plants: The Forward Osmosis-Based Actuator

Science.gov (United States)

Sinibaldi, Edoardo; Argiolas, Alfredo; Puleo, Gian Luigi; Mazzolai, Barbara

2014-01-01

Osmotic actuation is a ubiquitous plant-inspired actuation strategy that has a very low power consumption but is capable of generating effective movements in a wide variety of environmental conditions. In light of these features, we aimed to develop a novel, low-power-consumption actuator that is capable of generating suitable forces during a characteristic actuation time on the order of a few minutes. Based on the analysis of plant movements and on osmotic actuation modeling, we designed and fabricated a forward osmosis-based actuator with a typical size of 10 mm and a characteristic time of 2–5 minutes. To the best of our knowledge, this is the fastest osmotic actuator developed so far. Moreover, the achieved timescale can be compared to that of a typical plant cell, thanks to the integrated strategy that we pursued by concurrently addressing and solving design and material issues, as paradigmatically explained by the bioinspired approach. Our osmotic actuator produces forces above 20 N, while containing the power consumption (on the order of 1 mW). Furthermore, based on the agreement between model predictions and experimental observations, we also discuss the actuator performance (including power consumption, maximum force, energy density and thermodynamic efficiency) in relation to existing actuation technologies. In light of the achievements of the present study, the proposed osmotic actuator holds potential for effective exploitation in bioinspired robotics systems. PMID:25020043

Another lesson from plants: the forward osmosis-based actuator.

Science.gov (United States)

Sinibaldi, Edoardo; Argiolas, Alfredo; Puleo, Gian Luigi; Mazzolai, Barbara

2014-01-01

Osmotic actuation is a ubiquitous plant-inspired actuation strategy that has a very low power consumption but is capable of generating effective movements in a wide variety of environmental conditions. In light of these features, we aimed to develop a novel, low-power-consumption actuator that is capable of generating suitable forces during a characteristic actuation time on the order of a few minutes. Based on the analysis of plant movements and on osmotic actuation modeling, we designed and fabricated a forward osmosis-based actuator with a typical size of 10 mm and a characteristic time of 2-5 minutes. To the best of our knowledge, this is the fastest osmotic actuator developed so far. Moreover, the achieved timescale can be compared to that of a typical plant cell, thanks to the integrated strategy that we pursued by concurrently addressing and solving design and material issues, as paradigmatically explained by the bioinspired approach. Our osmotic actuator produces forces above 20 N, while containing the power consumption (on the order of 1 mW). Furthermore, based on the agreement between model predictions and experimental observations, we also discuss the actuator performance (including power consumption, maximum force, energy density and thermodynamic efficiency) in relation to existing actuation technologies. In light of the achievements of the present study, the proposed osmotic actuator holds potential for effective exploitation in bioinspired robotics systems.

Another lesson from plants: the forward osmosis-based actuator.

Directory of Open Access Journals (Sweden)

Edoardo Sinibaldi

Full Text Available Osmotic actuation is a ubiquitous plant-inspired actuation strategy that has a very low power consumption but is capable of generating effective movements in a wide variety of environmental conditions. In light of these features, we aimed to develop a novel, low-power-consumption actuator that is capable of generating suitable forces during a characteristic actuation time on the order of a few minutes. Based on the analysis of plant movements and on osmotic actuation modeling, we designed and fabricated a forward osmosis-based actuator with a typical size of 10 mm and a characteristic time of 2-5 minutes. To the best of our knowledge, this is the fastest osmotic actuator developed so far. Moreover, the achieved timescale can be compared to that of a typical plant cell, thanks to the integrated strategy that we pursued by concurrently addressing and solving design and material issues, as paradigmatically explained by the bioinspired approach. Our osmotic actuator produces forces above 20 N, while containing the power consumption (on the order of 1 mW. Furthermore, based on the agreement between model predictions and experimental observations, we also discuss the actuator performance (including power consumption, maximum force, energy density and thermodynamic efficiency in relation to existing actuation technologies. In light of the achievements of the present study, the proposed osmotic actuator holds potential for effective exploitation in bioinspired robotics systems.

Development of an Upper Limb Power Assist System Using Pneumatic Actuators for Farming Lift-up Motion

Science.gov (United States)

Yagi, Eiichi; Harada, Daisuke; Kobayashi, Masaaki

A power assist system has lately attracted considerable attention to lifting-up an object without low back pain. We have been developing power assist systems with pneumatic actuators for the elbow and shoulder to farming support of lifting-up a bag of rice weighing 30kg. This paper describes the mechanism and control method of this power assist system. The pneumatic rotary actuator supports shoulder motion, and the air cylinder supports elbow motion. In this control method, the surface electromyogram(EMG) signals are used as input information of the controller. The joint support torques of human are calculated based on the antigravity term of necessary joint torques, which are estimated on the dynamics of a human approximated link model. The experimental results show the effectiveness of the proposed mechanism and control method of the power assist system.

Polypyrrole Actuators Working at 2 to 30 Hz

DEFF Research Database (Denmark)

Skaarup, Steen; Bay, Lasse; West, Keld

2007-01-01

“Soft actuators” based on the conducting polymer polypyrrole (PPy) may be especially suitable for use in combination with human limbs. A research project under the European Union Quality of Life program (DRIFTS, Dynamically Responsive Intervention for Tremor Suppression, http://www.gerontech.org.......“Soft actuators” based on the conducting polymer polypyrrole (PPy) may be especially suitable for use in combination with human limbs. A research project under the European Union Quality of Life program (DRIFTS, Dynamically Responsive Intervention for Tremor Suppression, http......://www.gerontech.org.il/drifts/) focuses on the development of practical tremor suppression orthoses prototypes [1]. One of the choices of actuation mechanism is to use conducting polymers. The main challenge is to provide significant forces at the frequencies relevant to tremor in upper limbs: 2-16 Hz. Forces in the range of 0.1-1 kg......, and 0.32 mm at 15 Hz for the 1 kg limit. The required mass of the actuator itself at 15 Hz is ~100 mg. The results indicate the feasibility of using PPy actuators for tremor suppression....

A wireless actuating drug delivery system

International Nuclear Information System (INIS)

Jo, Won-Jun; Baek, Seung-Ki; Park, Jung-Hwan

2015-01-01

A wireless actuating drug delivery system was devised. The system is based on induction heating for drug delivery. In this study, thermally generated nitrogen gas produced by induction heating of azobisisobutyronitrile (AIBN) was utilized for pressure-driven release of the drug. The delivery device consists of an actuator chamber, a drug reservoir, and a microchannel. A semicircular copper disc (5 and 6 mm in diameter and 100 µm thick), and thermal conductive tape were integrated as the heating element in the actuator chamber. The final device was 2.7 mm thick. 28 µl of drug solution were placed in the reservoir and the device released the drug quickly at the rate of 6 µl s −1 by induction heating at 160 µT of magnetic intensity. The entire drug solution was released and dispersed after subcutaneous implantation under identical experimental condition. This study demonstrates that the device was simply prepared and drug delivery could be achieved by wireless actuation of a thin, pressure-driven actuator. (paper)

Sealing-free fast-response paraffin/nanoporous gold hybrid actuator

Science.gov (United States)

Ye, Xing-Long; Jin, Hai-Jun

2017-09-01

Paraffin-based actuators can deliver large actuation strokes and high actuation stress, but often suffer from a low response rate and leaking problems. Here, we report a new paraffin/metal hybrid actuator, which was fabricated by infiltrating nanoporous gold with paraffin. It exhibits a fast actuation rate owing to the high thermal conductivity of the inter-connected metal phase, and requires no external sealing because liquid paraffin can be well confined in nanoscale channels, due to the large capillarity. We found that in this hybrid actuator, the stress generated by actuation is negligibly small when the characteristic size of the nanoporous gold (L) is above ˜70 nm, and increases dramatically with a decreasing size when L paraffin wax—the paraffin in smaller pores can sustain larger tensile stress, and thus the contraction of paraffin during cooling can be translated into larger compression stress and strain energy in a metal framework, leading to a larger actuation stress and energy. We also demonstrate that complex actuation motions can be achieved by incorporating hierarchical-structured nanoporous metal with paraffin.

Dynamic Electromechanical Coupling of Piezoelectric Bending Actuators

Directory of Open Access Journals (Sweden)

Mostafa R. A. Nabawy

2016-01-01

Full Text Available Electromechanical coupling defines the ratio of electrical and mechanical energy exchanged during a flexure cycle of a piezoelectric actuator. This paper presents an analysis of the dynamic electromechanical coupling factor (dynamic EMCF for cantilever based piezoelectric actuators and provides for the first time explicit expressions for calculation of dynamic EMCF based on arrangement of passive and active layers, layer geometry, and active and passive materials selection. Three main cantilever layer configurations are considered: unimorph, dual layer bimorph and triple layer bimorph. The actuator is modeled using standard constitutive dynamic equations that relate deflection and charge to force and voltage. A mode shape formulation is used for the cantilever dynamics that allows the generalized mass to be the actual mass at the first resonant frequency, removing the need for numerical integration in the design process. Results are presented in the form of physical insight from the model structure and also numerical evaluations of the model to provide trends in dynamic EMCF with actuator design parameters. For given material properties of the active and passive layers and given system overall damping ratio, the triple layer bimorph topology is the best in terms of theoretically achievable dynamic EMCF, followed by the dual layer bimorph. For a damping ratio of 0.035, the dynamic EMCF for an example dual layer bimorph configuration is 9% better than for a unimorph configuration. For configurations with a passive layer, the ratio of thicknesses for the passive and active layers is the primary geometric design variable. Choice of passive layer stiffness (Young’s modulus relative to the stiffness of the material in the active layer is an important materials related design choice. For unimorph configurations, it is beneficial to use the highest stiffness possible passive material, whereas for triple layer bimorph configurations, the passive