Design issues in a decoupled XY stage: Static and dynamics modeling, hysteresis compensation, and tracking control

This paper presents fundamental issues in establishing a decoupled XY stage for micro/nano positioning and manipulation applications. In the proposed XY stage, two piezoelectric actuators (PEAs) generate motions, and the cross-axis couplings are attenuated by statically indeterminate symmetric (SIS) structures. In static and dynamics modeling, the PEA can be treated as a force generator with a built-in spring-damper component. Subsequently, the driving force of the PEA is characterized as the input into the system, which removes the PEA's nonlinearities out of the linear dynamics of the stage. The influence of the contact interface between the PEA and the stage is analytically investigated. For the proposed XY stage, the hysteresis of the PEA is compensated by cascading an inverse Prandtl-Ishlinskii (PI) model as a feedforward hysteresis compensator. A feedforward–feedback compound controller is also established to improve the tracking performance. Experimental results demonstrate that the tracking error can be reduced to the noise level on tracking 1-Degree-Of-Freedom (1-DOF) trajectories at low frequencies; for 2-DOF trajectories, the tracking error is influenced by the cross-axis couplings and the cooperative tracking performance between axes.