Analytical dynamic modeling of a cantilever IPMC actuator based on a distributed electrical circuit

Ionic polymer-metal composite (IPMC) has a wide range of applications in robotics, biomedical devices and artificial muscles. The modeling of the IPMC actuator is a multi-physics task as it involves electricity, chemistry, dynamics and control. Due to its complexity and its nonlinearity, IPMC modeling is difficult and its behavior is still not fully agreed upon by researchers. In this paper, a dynamic model of a cantilever IPMC actuator based on a distributed RC electrical circuit is developed. The RC transmission line theory is used to derive the simple analytical impedance and actuation model of an IPMC actuator. This method permits us to identify the current and voltage as functions of polymer length and frequency. First, an infinite-dimensional impedance model is developed and then replaced with a simple second-order electro-mechanical model using the Golubev method. The proposed modeling approach is validated using existing experimental data.