Position control system using ER clutch and piezoactuator

This paper presents ultra precision positioning system consisting of electrorheological(ER) clutch and piezoelectric actuators using dual servo control mechanism. ER clutch and ball screw are adopted for a coarse positioning stage, and magnification device driven by multi-stack piezoelectric actuator is manufactured for a fine positioning stage. After deriving the dynamic modeling for coarse motion stage, a sliding mode controller is designed to achieve robust control performance. In addition, conventional PID controller incorporated with the hysteresis nonlinearity of the piezoelectric actuator is designed to construct a feed-back with feed-forward control scheme for precise and fast positioning of the fine motion stage. Step regulating control performance of the proposed dual servo system is evaluated via experimental works to verify the effectiveness of the proposed position control system.