Hysteresis Observer Design of Sliding Mode Control for Piezoelectric Actuators

Piezoelectric actuators (PEAs) have been widely used in micro fabrication. But the hysteresis inherited in PEAs leads to a severe inaccuracy and deteriorated tracking performance. In this paper, a hysteresis observer is designed for PEAs to estimate the hysteresis, mechanical parameter varieties, positioning error and external disturbance. A Bouc-Wen model is associated with a linear second-order mass-damping-spring trio to model the dynamics. An asymptotic sliding surface is selected. Lyapunov stability theory is applied to guarantee the asymptotical stability for the trajectory tracking error. Experiments are conducted to validate the effectiveness of the proposed method. Results show that a satisfied tracking response to a sinusoidal trajectory is achieved, and the positioning errors under a triangle scanning contour are dramatically reduced compared with the traditional SMC.