Backstepping Sliding Mode Control Of A Dual-stage Actuator System

With the rapid development of science and technology, the requirement on the quality and accuracy of the products with high technologies are increasing. In the field of precision machining, low precision, low quality products have been unable to meet people’s needs, product up grading and transformation has become an inevitable trend.The dual-stage actuator(DSA) system combines the traditional actuator which is of long travel range with the smart-material-based actuator which is of high precision.Meanwhile, it effectively solves the contradiction between the long travel and high precision.In this dissertation, the mathematical models are established and the controllers are designed for the first actuator and the second actuator respectively, and the two actuators are united through a coordination factor.(1) First, the mathematical model is established and the controller is designed for the first actuator. The first actuator uses conventional servo motor. Via the analysis of the physical characteristics and driving method, the mathematical model is built. The controller design is based on Fuzzy-PID controller.The simulation results illustrate the practicability of the proposed method.(2) Then, the mathematical model is established and the controller is designed for the second actuator. The second stage actuator is usually used in smart materials such as giant magnetostrictive material and piezoelectric ceramics. However, the intelligent materials generally have the characteristics of non-smooth and multi-valued mapping. The hysteresis can directly affect the control accuracy of the system. The second actuator system Hysteresis phenomenon which is non-smooth and multi-valued mapping in smart-material-based actuators is also considered in this dissertation. The Bouc-Wen model is employed to describe hysteresis phenomenonfor the nonlinear system. A backstepping controller combining with sliding mode control is proposed. According to the characteristics of variables in Bouc-Wen model,the control method of backstepping sliding mode control method is used to design the controller of the hysteretic system. The control schemes can not only guarantee the tracking accuracy, but also improve the transient and steady-state performance. The simulation results show that the control scheme is feasible.(3) Last, the coordinating controller is designed for the DSA system. When the single actuator meets the operating system of the large stroke on the lack of control accuracy, when meeting the control accuracy can not meet the large stroke control. In order to solve the contradiction between first actuator and second actuator, the experts and scholars put forward the idea of the double- level executive coordination control. A coordination factor is designed to realize the coordination of two actuators and overcome the default of long setting time caused by designing separated controllers for the DSA system. The adjustable parameter of the coordination factor is selected by the integrated performance index. To demonstrate the effectiveness of this scheme, we simulate this scheme, the results show that can reduce the setting time effectively.