RESEARCH AND DEVELOPMENT OF PIEZO-ACTUATOR DRIVEN MICRO-DISPLACEMENT SYSTEM WITH THREE DEGREES OF FREEDOM

摘要

Based on the flexible double parallel four-bar mechanism, a micro-displacement system with 3 DOFs (X-Y- θ) is designed. A mechanical model of the micro-displacement mechanism is established. Static and dynamic analyses of the micro-displacement mechanism are made by traditional method and finite element method. Results of finite element analysis are very close to the results by traditional method based on the mechanical model proposed in this paper. A control system for the micro-displacement system is developed, in which the self-tuning PD-PID multiple-control algorithm is used. Effects of hysteresis and creep of piezoelectric actuator are reduced by using half-closed loop control system. Static and dynamic performances of the micro-displacement system are tested by laser interferometer and the results show that 1 μm positioning accuracy can be realized and the response time is within 2s for a step input in the micro- displacement system.