Sliding-mode control for a two-dimensional piezo-positioning stage

A sliding-mode controller (SMC) for a two-dimensional piezo-positioning stage is proposed. A mathematical model representing the motion dynamics of the stage is developed in which a hysteresis friction force describing the hysteresis behaviour of one-dimensional motion is used and a non-contant stiffness with the cross-coupling dynamics due to the effect of bending of lever mechanism in the x and y axes is also included. Based on the dynamic model, the proposed SMC with an asymptotic sliding surface is designed. A stability analysis is performed, and the transient performance is governed by the choice of control parameter values. With the proposed control scheme, the piezo-positioning stage is suitable for practical applications, especially in microscopy, with its need for validity of various trajectories. Experimental results show that the proposed controller provides high-performance dynamic characteristics and robustness to external load.