Microscale position control of an electroactive polymer using an anti-windup scheme
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abstract
Smart materials have been widely used for control actuation. In this paper, we present a microscale position control system using a novel electroactive polymer (EAP). We built a third-order model based on the system identification of the EAP actuator with an autoregressive moving average with exogenous input (ARMAX) method using a chirp signal input from 0.01Hz to 1Hz with the magnitude limited to 7V. With the derived plant model, we designed a digital PID (proportional-integral-derivative) controller with an integrator anti-windup scheme. We provide test results on macro (0.8mm) and micro (50m) step responses of the EAP actuator, and its position tracking capability is demonstrated. The overshoot decreased from 79.7% to 37.1% and the control effort decreased by 16.3%. The settling time decreased from 1.79s to 1.61s. The controller with the anti-windup scheme effectively reduced the degradation in the system performance due to actuator saturation. EAP microgrippers based on the control scheme presented in this paper will have significant applications including picking-and-placing micro-sized objects or as medical instruments. 2006 IOP Publishing Ltd.