William Nagel wins Best Session Presentation Award for paper entitled, “Master- Slave Control with Hysteresis Inversion for Dual-Stage Nanopositioning Systems”, at the American Control Conference in Boston, MA, July 6-8, 2016. His co-authors are Prof. Garrett Clayton of Villanova University and Prof. Kam Leang (William’s Ph.D. adviser at the University of Utah Robotics Center).
ABSTRACT:
This paper focuses on motion control of a piezo-based dual-stage nanopositioner where hysteresis and dynamic effects dominate the output response. A typical dual-stage micro/nano-scale positioning system consists of a long-range, low-speed actuator connected in series with a short-range, high-speed actuator. This arrangement allows for fast, long-range, and precise positioning. The main challenges, however, are that both hysteresis and dynamic effects (induced structural vibrations and creep) cause excessive positioning error and the control design problem requires balancing the relative contributions of the individual actuators (range, speed, and precision). To enable high-performance operation, a feedforward master-slave controller with hysteresis compensation is proposed. First, the Prandtl-Ishlinskii hysteresis model is exploited for inversion-based hysteresis compensation to linearize the response of each actuator. Then, a feedforward master-slave controller is used to minimize the dynamic effects and provide a systematic way to balance the relative contributions of the two actuators. A detailed presentation of the control structure is presented, followed by showing simulation and experimental results to demonstrate the efficacy of the approach.