Modeling of a Bending Supercoiled Polymer (SCP) Artificial Muscle

As a recently developed artificial muscle, supercoiled polymer (SCP) actuators exhibit many desirable properties such as inherent compliance, large linear tensile actuation, and high energy and power densities. By embedding linear SCP actuators into flexible beams and activating them, bending SCP actuators can be created with outstanding deflection performances. However, their full potential as bending robotic muscles is challenged by their hysteresis nonlinearity and the complex coupling between the beam and the linear SCP actuator. In this study, we propose a nonlinear model that can accurately capture and estimate the steady-state displacement of the bending SCP actuator. The proposed model is constructed by coupling a Preisach hysteresis model and nonlinear beam equations. Numerical solution is obtained using a bisection technique-based algorithm and Runge-Kutta method. For comparison purposes, a linear model is also considered. Both simulation and experimental investigations are conducted. The effectiveness of the proposed modeling approach is confirmed.