Modelling trilayer conjugated polymer actuators for their sensorless position control

In this paper, we present a new model to describe the displacement response of a trilayer conjugated polymer actuator that can operate in dry environments. The proposed model based on the working principle of conjugated polymer actuators includes diffusion impedances combined with double layer capacitors and charge transfer resistors. The parameters of the model are estimated by using a nonlinear least square estimation method by comparing simulation and experimental results. The proposed model is very useful in predicting the impedance as well as the displacement response of the polymer actuators accurately. Based on the proposed model, an inversion-based controller not requiring an external sensor for position feedback data is implemented and compared with the experimental results. The experimental position control results have confirmed the feasibility and efficacy of the proposed model in describing the time response of the actuators and their position control without using externally provided position data.