Closed loop control of dielectric elastomer actuators

Sensing the electrical characteristics of a Dielectric Elastomer Actuator(s) (DEA) during actuation is critical to improving their accuracy and reliability. We have created a self-sensing system for measuring the equivalent series resistance of the electrodes, leakage current through the equivalent parallel resistance of the dielectric membrane, and the capacitance of the DEA whilst it is being actuated. This system uses Pulse Width Modulation (PWM) to simultaneously generate an actuation voltage and a periodic oscillation that enables the electrical characteristics of the DEA to be sensed. This system has been specifically targeted towards low-power, portable devices. In this paper we experimentally validate the self-sensing approach, and present a simple demonstration of closed loop control of the area of an expanding dot DEA using capacitance feedback.