Novel multirate control strategy for piezoelectric actuators

In this article, a novel control method is proposed for feedforward compensation of hysteresis non-linearity in various frequency ranges. By integrating a multirate hysteresis compensator controller with PID feedback control, a combined controller is developed and experimentally validated for a piezoelectric micro-positioning system. Piezoelectric materials show non-linear hysteresis behaviour when they experience an electrical field. A fundamental study of a piezoelectric actuator (PEA) shows that the hysteresis effect deteriorates the tracking performance of the PEA. This paper presents a non-linear model which quantifies the hysteresis non-linearity generated in PEAs in response to the applied driving voltages. The tracking control method is based on multirate feedforward control. The proposed multirate control method uses an inverse modified Prandtl-Ishlinskii operator to cancel out hysteresis non-linearity. The controller structure has a simple design and can be quickly identified. The control system is capable of achieving suitable tracking control and it is convenient to use and can be quickly applied to practical PEA applications. Experimental results are provided to verify the efficiency of the proposed method.