Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers and have many potential applications in biomedical, robotic and micro/nano manipulation systems. In this paper, a nonlinear, control-oriented model is proposed for IPMC actuators. A key component in the proposed model is the nonlinear capacitance of IPMC. A nonlinear partial differential equation (PDE), which can capture the fundamental physics in IPMC, is fully considered in the derivation of nonlinear capacitance. A systems perspective is taken to get the nonlinear mapping from the voltage to the induced charge by analytically solving the nonlinear PDE at the steady state when a step voltage is applied. The nonlinear capacitance is incorporated into a circuit model, which includes additionally the pseudocapacitance due to the electrochemical adsorption process, the ion diffusion resistance, and the nonlinear DC resistance of the polymer, to capture electrical dynamics of IPMC. With electrome...
Zheng Chen, Dawn R. Hedgepeth, Xiaobo Tan