Design,identification,and control of piezoactuated positioning mechanism based on adaptive inverse method

Precision positioning mechanisms using piezoelectric stack actuators have a very wide range of applications. However, loss of tracking positioning precision in piezoelectric actuators occurs as a result of hysteresis during long-range applications and creep effects. This paper proposes two models that can simultaneously describe the hysteresis and creep phenomena of a piezoelectric actuator. Based on the hysteresis model and creep model, an adaptive inverse control approach is presented for improving the tracking performance of piezo-nanopositioning. The inverse controller is identified by using least mean square algorithm. The realization of the 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. The experimental results demonstrate that the positioning precision is noticeably improved in open-loop operation compared with the conventional open-loop control without any compensation.