Tracking control of piezoelectric actuators by feedforward hysteresis compensation

Due to the inherent hysteresis nonlinearity, the piezoelectric actuator always causes positioning error in the open-loop operation and instability in the closed-loop operation. In order to improve the positioning accuracy and response speed, a control method for piezoelectric actuator based on a PID feedback controller with a feedforward compensation is proposed. The feedforward controller based on a new mathematical model is used to describe the nonlinearity of piezoelectric actuator and improve the response speed. The feedback controller consists of a regular PID controller, which is used to improve the positioning accuracy. Finally, the tracking control experiments of piezoelectric actuators for a desired sinusoidal trajectory are performed according to the proposed control method and the experimental results demonstrate that the positioning precision is noticeably improved by augmenting the feedback controller with a model of hysteresis in the feedforward loop. The maximum error in tracking a sinusoidal signal is lowered about one order of magnitude in comparison with only using PID controller.