Robust Adaptive Control of Conjugated Polymer Actuators

• Published in: IEEE transactions on control systems technology Vol. 16; no. 4; pp. 600 - 612
• Main Authors: Yang Fang, Xiaobo Tan, Alici, G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.07.2008; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Actuation; Actuators; Adaptative systems; Adaptive control; Applied sciences; Artificial muscles; Biological materials; Biomedical materials; Computer science; control theory; systems; conjugated polymer actuators; Control system synthesis; Control theory. Systems; Dynamical systems; Dynamics; Error correction; Exact sciences and technology; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mathematical models; model reduction; Noise robustness; physical model; Physics; Pi control; Polymers; polypyrrole (PPy); Proportional integral derivative; Robotics; Robots; robust adaptive control; Robust control; Studies; Three-term control; Transducers; Artificial muscle; Tracking; Model following; Control synthesis; polypyrrole (PPy); Adaptive control; Modeling; Robotics; Posture; Time varying system; robust adaptive control; Biomimetics; Unmodeled dynamics; Dynamic measurement; Physical model; System reduction; Biomaterial; Infinite dimension; System identification; Micromanipulation; Solvent; Actuator; Biomedical engineering; Selftuning control; model reduction; Polymer; Evaporation; Experimental study; Robust control; Artificial muscles; Material engineering; conjugated polymer actuators; Robot; Signal to noise ratio
• ISSN: 1063-6536; 1558-0865
• DOI: 10.1109/TCST.2007.912112

Conjugated polymers are promising actuation materials for bio- and micromanipulation systems, biomimetic robots, and biomedical devices. Sophisticated electrochemomechanical dynamics in these materials, however, poses significant challenges in ensuring their consistent, robust performance in applications. In this paper, an effective adaptive control strategy is proposed for conjugated polymer actuators. A self-tuning regulator is designed based on a simple actuator model, which is obtained through reduction of an infinite-dimensional physical model and captures the essential actuation dynamics. The control scheme is made robust against unmodeled dynamics and measurement noises with parameter projection, which forces the parameter estimates to stay within physically meaningful regions. The robust adaptive control method is applied to a trilayer polypyrrole (PPy) actuator that demonstrates significant time-varying actuation behavior in air due to the solvent evaporation. Experimental results show that, during 4-h continuous operation, the proposed scheme delivers consistent tracking performance with the normalized tracking error decreasing from 11% to 7%, while the error increases from 7% to 28% and to 50% under a proportional-integral-derivative (PID) controller and a fixed model-following controller, respectively. In the meantime, the control effort under the robust adaptive control scheme is much less than that under PID, which is important for prolonging the lifetime of the actuator.