Enhancement of Tracking Performance for Piezo-Nanopositioning Stage

Nano-positioning systems using piezoelectric stack actuator have a very wide range of applications including ultra-precision machine tools, diamond turning machines and motion stage. However, loss of tracking positioning precision in piezoelectric actuator occurs due to hysteresis during long range applications and creep effects when positioning is needed over extended periods of time. This paper describes a method for simultaneous compensation of the hysteresis and creep of piezoelectric actuator based on an inverse controller. Based on the hysteresis model and creep model, an adaptive inverse control approach is presented for improving tracking performance of piezo-nanopositioning. The inverse model of creep is identified by using LMS algorithm. The realization of an adaptive inverse controller for the linearization of a piezoelectric actuator is formulated. Finally, a tracking control experiment of piezoelectric actuators for a desired trajectory is performed according to the proposed method and the experimental results demonstrate that the positioning precision is noticeably improved in open-loop operation compared to the conventional open-loop control without any compensation.