Control-oriented Nonlinear Modeling of Polyvinyl Chloride (PVC) Gel Actuators

Polyvinyl chloride (PVC) gel-based actuators are a new class of soft, electroactive polymer actuators with several attractive properties, including low cost, large compliance, large strain output, high-stress output, fast response, and stability against thermal influence. While PVC gel actuators are quickly gaining attention, they remain largely unexplored despite their great potential in a long list of applications compared with many other smart material actuators. In particular, little work has been reported on modeling nonlinear dynamics of PVC actuators. In this work a nonlinear, control-oriented Hammerstein model, with a polynomial nonlinearity preceding a transfer function, is proposed to capture the amplitude-dependent frequency responses of PVC gel actuators. A systematic procedure for identifying the model parameters is developed. The efficacy of the modeling approach is demonstrated with experimental voltage-displacement data collected from a PVC gel actuator prototype, where the model is able to predict the input amplitude-dependent dynamic response.