Position control of a dual-servo stage featuring an electrorheological fluid clutch and piezostack actuator

摘要

In this work, a novel type of dual-servo stage system is proposed in order to achieve accurate position control. A bidirectional electrorheological fluid clutch is adopted for a coarse-positioning stage, and a multi-stack piezoceramic actuator associated with a displacement amplifier for a fine-positioning stage. After deriving the dynamic model of the coarse-motion stage, a sliding-mode controller associated with a friction compensator is formulated to achieve robust position control performance. In addition, a model-based feedforward compensator incorporating a conventional proportional-integral-derivative controller is designed to compensate the hysteresis non-linearity of the fine-positioning stage. These controllers are experimentally realized in a decentralized strategy and control responses such as step input response are evaluated to verify the effectiveness of the proposed dual-servo positioning system.