Modelling and compound control of intelligently dielectric elastomer actuator

Abstract

This paper proposes the modelling and compound control methods for the intelligently dielectric elastomer actuator (IDEA) to realize its dynamic modelling and tracking control objectives. Firstly, we establish a dynamic model of the IDEA by cascading a square input module, a hysteresis model and a linear system, which can simultaneously characterize its asymmetrical and rate-dependent hysteresis behaviours, creep behaviour, as well as vibration behaviour. Then, by cascading the inverse solutions of the hysteresis model and the linear system, as well as the square root function module, an inverse compensation feedforward controller (ICFC) is designed to compensate the aforementioned behaviours of the IDEA in the tracking control. Moreover, considering that the uncertainties of the real system (including the modelling error, model parameter perturbation and external disturbance, etc.) are inescapable, a fuzzy proportional–integral feedback controller is designed to combine with the ICFC to enhance the tracking control performance, whose parameters are automatically adjusted by the fuzzy system. Finally, 6 groups of tracking control experiments with different target trajectories are performed. The maximum value of the relative root-mean-square errors of all experimental results is less than 3.1%, which demonstrates the effectiveness of the proposed compound control method of the IDEA.