Differential hysteresis modeling with adaptive parameter estimation of a super-coiled polymer actuator

The super-coiled polymer (SCP) actuator, made from silver coated fishing line which can be actuated by an electric current, is a recently discovered artificial muscle with interesting properties such as large contraction (20% - 50%), high power density (5.3 kW/kg), light weight and extremely low cost. In this paper, a differential hysteresis model with adaptive parameter estimation is presented for modeling of super-coiled polymer actuators. The operation of the actuator will be modeled with a heat transfer model and strain-temperature hysteresis model. At the heat of the strain-temperature hysteresis modeling is a differential hysteresis model which also incorporates the relationship between hysteresis curves and loads. In addition, adaptive model parameter estimation based on output feedback is applied to increase the performance of the model. The implementation results of the model show that the proposed model can effectively estimate the actuator's behavior, especially its hysteresis. This model can be used to develop a position controller for the super-coiled actuator.