Closed-Loop Control of Electro-Ribbon Actuators.

Autor:	Diteesawat RS; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.; Bristol Robotics Laboratory, Bristol, United Kingdom., Fishman A; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.; Bristol Robotics Laboratory, Bristol, United Kingdom., Helps T; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.; Bristol Robotics Laboratory, Bristol, United Kingdom., Taghavi M; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.; Bristol Robotics Laboratory, Bristol, United Kingdom., Rossiter J; Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.; Bristol Robotics Laboratory, Bristol, United Kingdom.
Jazyk:	angličtina
Zdroj:	Frontiers in robotics and AI [Front Robot AI] 2020 Nov 16; Vol. 7, pp. 557624. Date of Electronic Publication: 2020 Nov 16 (Print Publication: 2020).
DOI:	10.3389/frobt.2020.557624
Abstrakt:	Electro-ribbon actuators are lightweight, flexible, high-performance actuators for next generation soft robotics. When electrically charged, electrostatic forces cause the electrode ribbons to progressively zip together through a process called dielectrophoretic liquid zipping (DLZ), delivering contractions of more than 99% of their length. Electro-ribbon actuators exhibit pull-in instability, and this phenomenon makes them challenging to control: below the pull-in voltage threshold, actuator contraction is small, while above this threshold, increasing electrostatic forces cause the actuator to completely contract, providing a narrow contraction range for feedforward control. We show that application of a time-varying voltage profile that starts above pull-in threshold, but subsequently reduces, allows access to intermediate steady-states not accessible using traditional feed-forward control. A modified proportional-integral closed-loop controller is proposed (Boost-PI), which incorporates a variable boost voltage to temporarily elevate actuation close to, but not exceeding, the pull-in voltage threshold. This primes the actuator for zipping and drastically reduces rise time compared with a traditional PI controller. A multi-objective parameter-space approach was implemented to choose appropriate controller gains by assessing the metrics of rise time, overshoot, steady-state error, and settle time. This proposed control method addresses a key limitation of the electro-ribbon actuators, allowing the actuator to perform staircase and oscillatory control tasks. This significantly increases the range of applications which can exploit this new DLZ actuation technology. (Copyright © 2020 Diteesawat, Fishman, Helps, Taghavi and Rossiter.)
Databáze:	MEDLINE
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