Modeling And Control Method Research Of A Dual-stage Actuator System

As the technology and society develops,the traditional positioning accuracy has been unable to reach the demand of people,so the research of ultra precision positioning system has been valued by scholars.For the past years,the widely application of dual-stage actuator(DSA)system has promoted the development of ultra precision positioning.The DSA system combines the traditional actuator with the intelligence material actuator.It can achieve demand of large travel and high precision at same time.In this paper,the dual-stage actuator is developed by servo motor and piezoelectric actuator.It focus on modeling and controller designing of second actuator,and a coordinated control scheme base on spatial filter is developed to achieve the control of dual-stage actuator.The major works include:(1)Modeling of second actuatorA dynamic hysteresis model is developed based on dynamic hysteresis operator.A new3-D space is built according to the hysteresis operator.By means of the new space,multi-valued mapping can be transformed into one-to-one mapping.A novel ELM combining with Locally Linear Embedding(LLE)is proposed to approximate the above one-to-one mapping.This model has a rather simple architecture.Moreover,the proposed model possess high precision and can be adjusted online.(2)Controller designing of second actuatorAn adaptive control technique is developed for a class of nonlinear plants preceded by backlash-like.Firstly,the mean value theorem is employed to transform the pure-feedback system to a strict-feedback structure.Then the Barrier Lyapunov Function(BLF)is introduced to guarantee the full state constraints are not violated.Moreover,the RBFNN is adopted for online approximation of disturbance-like term separated from backlash-like hysteresis.Finally,an Adaptive controller is designed using backstepping method.The simulation results indicatethe effectiveness of the proposed scheme.(3)Coordinating controller designing of dual-stage systemA coordination scheme base on spatial filter is proposed.The signal can be separated into long-range and short-range.Then the controllers of dual-stage actuators can be designed separately based on the new signals.A proximate time-optimal controller is designed for first actuator in order to have a fast positioning.A multi-layer sliding mode controller is developed for second actuator to have a precise positioning.The proposed design reduce the difficulty of controller designing.The simulation result prove that this control method is practicable.