Optimal position control of ionic polymer metal composite using particle swarm optimization

Increasing research interest and immense development of electroactive polymers (EAP) has paved way for various micro positioning tasks and underwater applications. Ionic Polymer Metal Composite (IPMC) a subset of electroactive polymers encompasses a wide range of control applications. Open loop behavior of IPMC is often not repeatable and is always troublesome to maintain a constant specified tip-position in open loop. Also open loop response of IPMC is prone to a larger overshoot hence, an efficient closed loop IPMC control becomes evident for many high precision applications. In this article an optimal position control of IPMC based on Particle swarm optimization (PSO) technique is proposed. A comparative study of PI (Proportional integral) tuning parameters based on conventional Ziegler-Nichols (ZN) and PSO tuning technique is done. This comparative study accounts for various important step response characteristics like rise time, settling time and maximum overshoot. Ziegler-Nichols (ZN) tuned parameters ݇kp=22.24 and kl=1588.7 decreased the overshoot from 523% to 23.2% and reduced the settling time from 113s to 54.4ms. However the gain parameters ݇kp=668.0479 and ݇kl=1246.4 obtained from the Particle Swarm Optimization technique eliminated the overshoot and further reduced the settling time to 1.2ms successfully minimizing the closed loop error. Hence this study shows that PSO tuning technique is advantageous over conventional ZN method in estimating the optimal tuning parameters and thereby alleviating the system dynamic performance.