Trajectory tracking control of a piezoelectric stage for dynamic load applications

In this paper, a robust control approach using a novel hysteresis observer is developed for precise tracking control of piezoelectric actuators (PEAs). This control methodology considers the problems of unknown or uncertain system parameters, hysteresis non-linearity, and external load disturbances. For representing the behaviour of a PEA, a Bouc-Wen hysteresis model is integrated with a second-order linear dynamic. It is shown that the non-linear response of the model owing to the hysteresis effect acts as a bounded disturbance. Based on this fact a hysteresis observer is proposed to estimate the hysteresis effect. Then for real-time compensation of the observer error, parametric uncertainties, and external disturbances, a sliding mode control strategy with a perturbation estimation function is utilized. By using the proposed control approach the asymptotical stability in displacement tracking and robustness to the dynamic load disturbance can be provided. Finally, the proposed approach and conventional controllers are compared by experiments.