Study On The Space Micro-Displacement Platform

In this dissertation, the space micro-displacement platform featuring piezoelectric actuators is studied. The research focuses on the lightweight, micromation, and high precision positioning of the platform. This dissertation is arranged as follows.In chapter 1, the components of the micro-displacement system are analyzed which includes actuators' type, guideway's layout, the types and properties of sensors and control strategy. The present research situation in precision positioning micro-displacement platform at home and abroad is reviewed. The layout of guideways and types of actuators are determined considering the characteristic in space.In chapter 2, the micro-displacement platform using a flexure hinge guideway and a piezoelectric actuator is designed. Calculation formulas of parameters in a flexure hinge and a fast design method are given. The validity of the method is confirmed by finite element method and prototype model. By theoretical analysis and experiments, the properties of piezoelectric actuators are grasped. A DC driving power with high precision and high voltage is developed.In chapter 3, the control system of the space micro-displacement platform is set up and the transfer function is given. Digital integral formulas and experiment model data table that are suitable to computer control are acquired by modeling the hysteresis using the modified Preisach model. And a new power linearization for piezoelectric actuators based on iterative learning control (ILC) is given.In chapter 4, two open-loop precision positioning control methods are introduced, one is a fast voltage-displacement linearization based on iterative learning control (ILC), and the other uses the modified Preisach model to model the hysteresis. In addition, their application occasions and strong and weak points are represented. A close-loop precision positioning control method is studied on the micro-displacement system. Based on analyzing and discussing the PID algorithm, the dynamic response property of the system is improved by using the modified Preisach model as a feedforward segment. Precision positioning control is implemented with the excitation of ultra-low frequency disturbance. The results show that the proposed control algorithm has a good ability to suppress disturbance and meet the precision requirement.In chapter 5, main achievements of the dissertation are summarized and the further research work, which will be done in the near future now on is put forward.