Modeling and open-loop control of IPMC actuators under changing ambient temperature

Because of the cost and complexity associated with sensory feedback, open-loop control of ionic polymer–metal composite (IPMC) actuators is of interest in many biomedical and robotic applications. However, the performance of an open-loop controller is sensitive to the change in IPMC dynamics, which is influenced heavily by ambient environmental conditions including the temperature. In this paper we propose a novel approach to the modeling and open-loop control of temperature-dependent IPMC actuation dynamics. An IPMC actuator is modeled empirically with a transfer function, the zeros and poles of which are functions of the temperature. With auxiliary temperature measurement, open-loop control is realized by inverting the model at the current ambient temperature. We use a stable but noncausal algorithm to deal with non-minimum-phase zeros in the system that would prevent directly inverting the dynamics. Experimental results are presented to show the effectiveness of the proposed approach in open-loop tracking control of IPMC actuators. (Some figures may appear in colour only in the online journal)