On the Control of a Dielectric Elastomer Artificial Muscle With Variable Impedance

2013 ◽  
Author(s):  
Gianluca Palli ◽  
Giovanni Berselli
Keyword(s):  
Artificial Muscle ◽  
Artificial Muscles ◽  
Control Law ◽  
Model Uncertainties ◽  
Control Approach ◽  
Task Requirements ◽  
Linear Viscoelastic ◽  
Compensation Technique ◽  
Novel Strategy ◽  
Actuation Systems

Artificial Muscles based on Dielectric Elastomers (DE) can potentially enable the realization of bio-inspired actuation systems whose intrinsic compliance and damping can be varied according to the task requirements. Nonetheless, the control of DE-based Variable Impedance Actuators (VIA) is not trivial owing to the non-linear viscoelastic response which characterizes the acrylic dielectrics commonly employed in practical devices. In this context, the purpose of the present paper is to outline a novel strategy for the control of DE-based VIA. Although the proposed methodology is applicable to generic DE morphologies, the considered system is composed of a couple of conically-shaped DE films in agonistic-antagonistic configuration. Following previously published results, the system dynamic model is firstly recalled. Then, a DE viscoelasticity compensation technique is outlined together with a control law able to shape the DE actuator impedance as desired. The operative limits of the system are explicitly considered and managed in the controller by increasing the operating DE actuator stiffness if required. In addition, the problem of model uncertainties compensation is also addressed. Finally, as a preliminary step towards the realization of a practical DE-based VIA, the proposed control approach is validated by means of simulations.

Bioinspired passive variable recruitment of fluidic artificial muscles

2018 ◽  
Vol 29 (15) ◽  
pp. 3067-3081 ◽  
Author(s):  
Edward M Chapman ◽  
Matthew Bryant
Keyword(s):  
Control Method ◽  
Applied Pressure ◽  
Artificial Muscle ◽  
High Threshold ◽  
Artificial Muscles ◽  
Control Approach ◽  
Muscle Tissues ◽  
Wide Range ◽  
Variable Recruitment ◽  
Analogous Behavior

This article presents a novel, passive approach to creating variable actuator recruitment in bundles of fluidic artificial muscles. The passive recruitment control approach is inspired by the functionality of mammalian muscle tissues, in which a single activation signal from the nervous system sequentially triggers contraction of progressively larger actuation elements until the required force is generated. Biologically, this behavior is encoded by differences in electrical resistance properties between smaller and larger muscle-fiber groups. The approach presented here produces analogous behavior using a uniform applied pressure to all fluidic artificial muscles while creating differential pressure responses and threshold pressures among the fluidic artificial muscles via tailored bladder elasticity parameters. A model for using elastic bladder stiffness to control an artificial muscle bundle with a single valve is explored and used to compare a bundle of fluidic artificial muscles with both low and high threshold pressure units to a single fluidic artificial muscle of equivalent displacement and force capability. The results of this analysis indicate the efficacy of using this control method; it is advantageous in cases where a wide range of displacements and forces are necessary and can increase efficiency when the system primarily operates in a low-force regime but requires occasional bursts of high-force capability.

scholarly journals Theoretical Hill-Type Muscle and Stability: Numerical Model and Application

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
S. Schmitt ◽  
M. Günther ◽  
T. Rupp ◽  
A. Bayer ◽  
D. Häufle
Keyword(s):  
Numerical Model ◽  
Biomechanical Model ◽  
Artificial Muscle ◽  
Biomedical Science ◽  
Artificial Muscles ◽  
Control Approach ◽  
Inverted Pendulum Model ◽  
Walking Machines ◽  
Antagonistic Muscle ◽  
Force Velocity

The construction of artificial muscles is one of the most challenging developments in today’s biomedical science. The application of artificial muscles is focused both on the construction of orthotics and prosthetics for rehabilitation and prevention purposes and on building humanoid walking machines for robotics research. Research in biomechanics tries to explain the functioning and design of real biological muscles and therefore lays the fundament for the development of functional artificial muscles. Recently, the hyperbolic Hill-type force-velocity relation was derived from simple mechanical components. In this contribution, this theoretical yet biomechanical model is transferred to a numerical model and applied for presenting a proof-of-concept of a functional artificial muscle. Additionally, this validated theoretical model is used to determine force-velocity relations of different animal species that are based on the literature data from biological experiments. Moreover, it is shown that an antagonistic muscle actuator can help in stabilising a single inverted pendulum model in favour of a control approach using a linear torque generator.

Sliding Mode Impedance Control of a Hydraulic Artificial Muscle

2018 ◽  
Author(s):  
Jonathon E. Slightam ◽  
Mark L. Nagurka ◽  
Eric J. Barth
Keyword(s):  
Sliding Mode ◽  
Impedance Control ◽  
Artificial Muscle ◽  
Lumped Parameter Model ◽  
Superior Performance ◽  
Specific Power ◽  
Artificial Muscles ◽  
Control Approach ◽  
Model Based ◽  
Improved Performance

Hydraulic artificial muscles offer unrivaled specific power and power density and are instrumental to the improved performance and success of soft robotics and lightweight mobile applications. This paper addresses the lack of model-based impedance control approaches for soft actuators such as hydraulic artificial muscles. Impedance control of actuators and robotic systems has been proven to be an effective approach for interacting with physical objects in the presence of uncertainty. A sliding mode impedance control approach based on Filippov’s principle of equivalent dynamics is introduced and applied to a hydraulic artificial muscle. A nonlinear lumped parameter model of the system is presented and a sliding mode impedance controller is derived. Experimental results show superior performance using model-based sliding mode impedance control versus a linear impedance control law in both tracking of position and stiffness when disturbances are introduced.

scholarly journals Adaptive Optimal Robust Control for Uncertain Nonlinear Systems Using Neural Network Approximation in Policy Iteration

2021 ◽  
Vol 11 (5) ◽  
pp. 2312
Author(s):  
Dengguo Xu ◽  
Qinglin Wang ◽  
Yuan Li
Keyword(s):  
Neural Network ◽  
Optimal Control ◽  
Robust Control ◽  
Nonlinear Systems ◽  
Policy Iteration ◽  
Control Law ◽  
Globally Asymptotically Stable ◽  
Control Approach ◽  
Input Uncertainties ◽  
Theoretical Results

In this study, based on the policy iteration (PI) in reinforcement learning (RL), an optimal adaptive control approach is established to solve robust control problems of nonlinear systems with internal and input uncertainties. First, the robust control is converted into solving an optimal control containing a nominal or auxiliary system with a predefined performance index. It is demonstrated that the optimal control law enables the considered system globally asymptotically stable for all admissible uncertainties. Second, based on the Bellman optimality principle, the online PI algorithms are proposed to calculate robust controllers for the matched and the mismatched uncertain systems. The approximate structure of the robust control law is obtained by approximating the optimal cost function with neural network in PI algorithms. Finally, in order to illustrate the availability of the proposed algorithm and theoretical results, some numerical examples are provided.

Automatic Flight Control of Unmanned Helicopter Based on Nonlinear Model

2012 ◽  
Vol 472-475 ◽  
pp. 1492-1499
Author(s):  
Run Xia Guo
Keyword(s):  
Nonlinear Model ◽  
Flight Control ◽  
Attitude Control ◽  
Lyapunov Stability Theory ◽  
Test Results ◽  
Unmanned Helicopter ◽  
Control Laws ◽  
Control Approach ◽  
State Dependent ◽  
Compensation Technique

The Unmanned helicopter (UMH) movement was divided into two parts, namely, attitude and trajectory motion. And then a two-timescale nonlinear model was established. The paper improved and expanded state dependent riccati equation (SDRE) control approach, deriving analytical conditions for achieving global asymptotic stability with lyapunov stability theory. Proof was given. By combining improved SDRE control with nonlinear feed-forward compensation technique, the full envelop flight attitude control laws could be designed. On the basis of attitude control, trajectory controller was developed. Actual flight tests were carried out. Test results show that the control strategy is highly effective.

Macroporous smart gel based on pH-sensitive polyacrylic polymer for the development of large size artificial muscle with linear contraction

Soft Matter ◽  
2021 ◽  
Author(s):  
Vincent Mansard
Keyword(s):  
Soft Matter ◽  
Artificial Muscle ◽  
Ph Sensitive ◽  
Artificial Muscles ◽  
Linear Contraction ◽  
Large Size ◽  
Polyacrylic Polymer ◽  
The Revolution

The physics of soft matter can contribute to the revolution in robotics and medical prostheses.These two fields requires the development of artificial muscles with behavior close to the biologicalmuscle. Today,...

A Control Approach to Guide Nonpharmaceutical Interventions in the Treatment of COVID-19 Disease Using a SEIHRD Dynamical Model

2021 ◽  
Vol 30 (3) ◽  
pp. 323-346
Author(s):  
Fernando Pazos ◽  
◽  
Flavia E. Felicioni ◽  
Keyword(s):  
Public Health ◽  
Ad Hoc ◽  
Early Stage ◽  
Control Law ◽  
Parametric Uncertainties ◽  
Social Unrest ◽  
Control Approach ◽  
Health Measures ◽  
Optimal Intensity ◽  
Nonpharmaceutical Interventions

The recent worldwide epidemic of COVID-19 disease, for which there are no medications to cure it and the vaccination is still at an early stage, led to the adoption of public health measures by governments and populations in most of the affected countries to avoid the contagion and its spread. These measures are known as nonpharmaceutical interventions (NPIs), and their implementation clearly produces social unrest as well as greatly affects the economy. Frequently, NPIs are implemented with an intensity quantified in an ad hoc manner. Control theory offers a worthwhile tool for determining the optimal intensity of the NPIs in order to avoid the collapse of the healthcare system while keeping them as low as possible, yielding concrete guidance to policymakers. A simple controller, which generates a control law that is easy to calculate and to implement is proposed. This controller is robust to large parametric uncertainties in the model used and to some level of noncompliance with the NPIs.

scholarly journals Theoretical Comparison of McKibben-Type Artificial Muscle and Novel Straight-Fiber-Type Artificial Muscle

2011 ◽  
Vol 5 (4) ◽  
pp. 544-550 ◽  
Author(s):  
Hiroki Tomori ◽  
◽  
Taro Nakamura
Keyword(s):  
Steady State ◽  
Dynamic Characteristic ◽  
Fiber Type ◽  
Human Life ◽  
Artificial Muscle ◽  
Artificial Muscles ◽  
Contraction Rate ◽  
Theoretical Comparison ◽  
Straight Fiber ◽  
Force Characteristics

Robots have entered human life, and closer relationships are being formed between humans and robots. It is desirable that these robots be flexible and lightweight. With this as our goal, we have developed an artificial muscle actuator using straight-fiber-type artificial muscles derived from the McKibben-type muscles, which have excellent contraction rate and force characteristics. In this study, we compared the steady state and dynamic characteristic of straightfiber-type and McKibben-type muscles and verified the usefulness of straight-fiber-type muscles.

scholarly journals Phase transformation-driven artificial muscle mimics the multifunctionality of avian wing muscle

2021 ◽  
Vol 18 (184) ◽  
Author(s):  
Pedro B. C. Leal ◽  
Marcela Cabral-Seanez ◽  
Vikram B. Baliga ◽  
Douglas L. Altshuler ◽  
Darren J. Hartl
Keyword(s):  
Skeletal Muscle ◽  
Mechanical Performance ◽  
Dynamic Control ◽  
Artificial Muscle ◽  
Bipedal Walking ◽  
Artificial Muscles ◽  
Operational Conditions ◽  
Leg Muscles ◽  
Engineered Systems ◽  
Electrical Stimuli

Skeletal muscle provides a compact solution for performing multiple tasks under diverse operational conditions, a capability lacking in many current engineered systems. Here, we evaluate if shape memory alloy (SMA) components can serve as artificial muscles with tunable mechanical performance. We experimentally impose cyclic stimuli, electric and mechanical, to an SMA wire and demonstrate that this material can mimic the response of the avian humerotriceps, a skeletal muscle that acts in the dynamic control of wing shapes. We next numerically evaluate the feasibility of using SMA springs as artificial leg muscles for a bipedal walking robot. Altering the phase offset between mechanical and electrical stimuli was sufficient for both synthetic and natural muscle to shift between actuation, braking and spring-like behaviour.

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