Ru Changhai

Tracking control of piezoelectric actuator based on a new mathematical model

A major deficiency of piezoelectric actuators is that their open-loop control accuracy is seriously limited by hysteresis. In this paper, a novel mathematical model is proposed to describe hysteresis precisely and a new parameter called turning voltage is introduced. It was found experimentally that the shapes of hysteresis curves are decided by the value of the turning voltage. A computer-based inverse control approach under open-loop operation based on the mathematical model was applied to suppress the inherent hysteresis to within ±1% full span range of a stack piezoelectric actuator and the performance of the piezoelectric actuator is noticeably improved.

Adaptive inverse control for piezoelectric actuator with dominant hysteresis

Piezoelectric actuator controlled by voltage shows serious hysteresis phenomena, which severely degrades the positioning accuracy. Based on Prandtle-Ishlinskii hysteresis operator, an adaptive inverse control approach is presented for reducing hysteresis. The weights of the model are identified by using LMS algorithm. The realization of an inverse feedforward controller for the linearization of a piezoelectric actuator is formulated. Experiments were performed on a micro-positioning system driven by piezoelectric actuators. The results show that the presented adaptive inverse control lowers the non-linearity error from about 17.3 to about 2% in comparison to the conventionally open-loop control.