Development of a piezoelectrically actuated dual-stage fast tool servo

By serially combining two piezoelectrically actuated compliant stages, a dual-stage fast tool servo (FTS) is developed to greatly enhance the trajectory tracking performance of conventional FTS, which is crucial for turning micro/nanostructured functional surfaces. By means of the matrix based compliance modeling method, mechanical performance of the dual-stage FTS is analytically modeled, and the structural dimensions are accordingly optimized with further verification through finite element analysis. With respect to the trajectory tracking, the master–slave control strategy is employed using a simple proportional-integration controller for the primary stage, and the primary control error is then tracked by the secondary stage through the system model based inversion-free open-loop control. For the system model, the Prandtl-Ishlinskii model cascading with the system dynamics model is established to describe the dynamic hysteresis. The basic working performance including both static and dynamic aspect is experimentally examined, and further tracking control of both simple harmonics and complicated commands having high working frequency is conducted, demonstrating the significantly improved performance of the dual-stage FTS for high frequency tracking.