Position control of an Ionic Polymer Metal Composite actuated rotary joint using Iterative Feedback Tuning

• Published in: Mechatronics (Oxford) Vol. 21; no. 1; pp. 315 - 328
• Main Authors: Liu, D., McDaid, A.J., Aw, K.C., Xie, S.Q.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01-02-2011; Elsevier
• Subjects: Adaptive PID Tuning; Applied sciences; Control systems; Control theory; Exact sciences and technology; Feedback; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Ionic Polymer Metal Composite (IPMC); Iterative Feedback Tuning (IFT); Iterative methods; Mechanical properties; Nonlinearity; Physical properties; Physics; Polyimide resins; Polymer industry, paints, wood; Properties and testing; Steady state; Technology of polymers; Transducers; Tuning; Adaptive PID Tuning; Iterative Feedback Tuning (IFT); Ionic Polymer Metal Composite (IPMC); Integral proportional control; Position control; Feedback regulation; Iterative method; Adaptive method; Transducer; Time varying system; Ion exchange membrane; Feedback; Mechanical characteristic; Linkage mechanism; Model free control; Intelligent system; Actuator; Ionomer; Transient response; Electroactive polymer; Mechanical properties; Steady state; Time response; Tuning; Electrochemical properties; Cation exchange membrane; Non linear effect
• ISSN: 0957-4158; 1873-4006
• DOI: 10.1016/j.mechatronics.2010.12.001

► Successfully demonstrated a model free approach for position control of an IPMC actuator driving an external single DOF rotary mechanism. ► We have successfully implemented an IFT as an adaptive tuning technique to improve the position control of an IPMC actuator. ► We have successfully demonstrated the position control of micrometer range using the IFT technique in a PI controller.
Ionic Polymer Metal Composites (IPMCs) are a novel material that has been the subject of considerable interest over recent decades because of their unique electrochemical and mechanical properties which allow them to be used as smart transducers. However, there has been insufficient research to determine if the electro-active polymer can reliably actuate common engineering mechanisms due to its nonlinear and time-variant nature. This paper explores a model-free approach for controlling the position of an IPMC actuated rotary linkage for micro-manipulation. The mechanism was developed based on the mechanical characteristics of the IPMC actuators. A Proportional, Integral (PI) controller was initially developed and tested to control the tip displacement of the mechanism. Test results show that this classical controller is capable of actuating the rotary mechanism to microscopic deflections but would not completely stabilise at the steady state position. An adaptive, nonlinear tuning method called Iterative Feedback Tuning (IFT) was developed to tune the performance of the PI controller. Empirical results show that the new control scheme improved the steady state response. However, the enhancement of the transient response could not be definitively validated as solely the work of the IFT algorithm due to the time-variant and variable response behaviour of IPMCs.