Chapter 11: Precision Feedback and Feedforward Control of Ionic Polymer Metal Composite Actuators

Ionic polymer metal composites (IPMCs), a type of electroactive polymer, are quickly gaining attention for use in many applications, including soft bio-inspired actuators and sensors. Some noteworthy advantages of IPMCs include their low driving voltage (<5 V) and the ability to be operated in aqueous environments. There are, however, drawbacks to IPMC actuators, including dynamics effects, the back-relaxation effect, and time-varying behaviors. These effects can limit the performance of IPMC-based actuators. This chapter focuses on feedback and feedforward control approaches for the precision control of IPMC actuators. In particular, a model-based feedforward controller is described to compensate for dynamic effects. Repetitive control (RC) is introduced for tracking period trajectories, and a method that exploits sectored IPMCs with an integrated feedback and feedforward controller is described to mitigate back-relaxation behavior. This chapter also discusses basic IPMC manufacturing techniques and methods for sensing displacement for sensor-based feedback control.