Control approach development for variable recruitment artificial muscles

2016 ◽  
Author(s):  
Tyler E. Jenkins ◽  
Edward M. Chapman ◽  
Matthew Bryant
Keyword(s):  
Artificial Muscles ◽  
Control Approach ◽  
Variable Recruitment

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.

Variable recruitment in bundles of miniature pneumatic artificial muscles

2016 ◽  
Vol 11 (5) ◽  
pp. 056014 ◽  
Author(s):  
Sylvie A DeLaHunt ◽  
Thomas E Pillsbury ◽  
Norman M Wereley
Keyword(s):  
Artificial Muscles ◽  
Pneumatic Artificial Muscles ◽  
Variable Recruitment

Variable recruitment fluidic artificial muscles: modeling and experiments

2014 ◽  
Vol 23 (7) ◽  
pp. 074009 ◽  
Author(s):  
Matthew Bryant ◽  
Michael A Meller ◽  
Ephrahim Garcia
Keyword(s):  
Artificial Muscles ◽  
Modeling And Experiments ◽  
Variable Recruitment

scholarly journals Bio-inspired online variable recruitment control of fluidic artificial muscles

2016 ◽  
Vol 25 (12) ◽  
pp. 125016 ◽  
Author(s):  
Tyler E Jenkins ◽  
Edward M Chapman ◽  
Matthew Bryant
Keyword(s):  
Artificial Muscles ◽  
Variable Recruitment

Design, analysis, and validation of an orderly recruitment valve for bio-inspired fluidic artificial muscles

2021 ◽  
Author(s):  
Dheeraj Vemula ◽  
Jeong Yong Kim ◽  
Nicholas Mazzoleni ◽  
Matthew Bryant
Keyword(s):  
Tracking Error ◽  
Cross Flow ◽  
Motor Units ◽  
Recruitment Strategy ◽  
Artificial Muscles ◽  
Robot Arm ◽  
Controlled System ◽  
Variable Recruitment ◽  
And Performance ◽  
Feed Forward Controller

Abstract Biological musculature employs variable recruitment of muscle fibers from smaller to larger units as the load increases. This orderly recruitment strategy has certain physiological advantages like minimizing fatigue and providing finer motor control. Recently fluidic artificial muscles (FAM) are gaining popularity as actuators due to their increased efficiency by employing these bio-inspired recruitment strategies such as active variable recruitment (AVR). AVR systems use a multi-valve system (MVS) configuration to selectively recruit individual FAMs depending on the load. However, when using an MVS configuration, an increase in the number of motor units in a bundle corresponds to an increase in the number of valves in the system. This introduces greater complexity and weight. The objective of this paper is to propose, analyze, and demonstrate an orderly recruitment valve (ORV) concept that enables orderly recruitment of multiple FAMs in the system using a single valve. A mathematical model of an ORV-controlled FAM bundle is presented and validated by experiments performed on an ORV prototype. The modeling is extended to explore a case study of a 1-DOF robot arm system consisting of an electrohydraulic pressurization system, ORV, and a FAM-actuated rotating arm plant and its dynamics are simulated to further demonstrate the capabilities of an ORV-controlled closed-loop system. An orderly recruitment strategy was implemented through a model-based feed forward controller. To benchmark the performance of the ORV, a conventional MVS with equivalent dynamics and controller was also implemented. Trajectory tracking simulations on both the systems revealed lower tracking error for the ORV controlled system compared to the MVS controlled system due to the unique cross-flow effects present in the ORV. However, the MVS, due to its independent and multiple valve setup, proved to be more adaptable for performance. For example, modifications to the recruitment thresholds of the MVS demonstrated improvement in tracking error, albeit with a sacrifice in efficiency. In the ORV tracking performance remained insensitive to any variation in recruitment threshold. The results show that compared to the MVS, the ORV offers a simpler and more compact valving architecture at the expense of moderate losses in control flexibility and performance.

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.

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