Dynamic linear modeling, identification and precise control of a walking piezo-actuated stage

Abstract

Abstract In this paper, a dynamic model is firstly investigated for a flexible mechanical stage driven by a walking piezoelectric actuator (WPA). The developed model takes into account the WPA, the mechanical stage and moreover the connection part between them as an overall piezo-actuated stage. The model of the WPA is derived mainly from the electrical, piezoelectric and mechanical sides. Besides, the WPA and mechanical stage are treated as elements with lumped mass. Then the proposed model is identified based on the open-loop frequency response data. Finally, hybrid closed-loop controllers are designed for point-to-point (PTP) positioning and sinusoidal trajectory tracking control of the overall piezo-actuated stage. The hybrid control strategy includes displacement error feedback and velocity feed-forward control algorithms. Furthermore, the transient profile and tracking differentiator is proposed for quick settling of PTP positioning control, and the discrete-time repetitive controller (RC) is adopted to enhance the tracking precision for the periodic sinusoidal trajectory. Experimental results show that for the 300 μ m PTP positioning the settling time is 0.12 s to keep the steady error within 25 nm, and for the sinusoidal trajectory of 50 μ m amplitude the maximum tracking error is 1.99%. These results clearly demonstrate the high precision performance of the developed hybrid controllers for the walking piezo-actuated stage.