Control design for piezoelectric actuator systems

Considering with the application specifics of the piezoelectric servo system, the piezoelectric ultrasonic motor is not appropriate for use as an actuator for high precision servo systems, and a piezoelectric stack structure was proposed for the system actuator. The Bouc-Wen model of hysteresis was proposed for modeling the hysteresis characteristic of the piezoelectric stack actuator. This model is more suitable for simulation studies. The nonlinear characteristic of hysteresis of the piezoelectric actuator was then analyzed based on the Bouc-Wen model. The compensation of the nonlinear hysteresis was also discussed. A feedback-based disturbance observer for hysteresis compensation was then proposed. The self-sustained oscillation problem for servo systems with piezoelectric hysteresis was further analyzed. The limit cycles caused by the hysteresis effect of backlash was also studied for comparison. It is pointed out that self-sustained oscillations cannot appear at all in a system with piezoelectric hysteresis in feedback. Based on the above analysis, a design guide for the piezoelectric servo system was proposed, and the simulation result was also presented.