Drive System Design And Control Research Of Precision Motion Platform

In order to short the gap with developed countries and develop the core technology of IC manufacturing equipment with independent intellectual property rights, it has great practical significance to do key technology research of bottom drive system based on the new drive mode, organization form, control method and displacement detection technology. The bottom drive system will be used in the high precision motion platform that aims to adjust and keep a steady flow field in the immersion lithography.Firstly, a wedge drive system based on linear ultrasonic motor was designed by taking Nanomotion linear ultrasonic motor as drive part and combining with the wedge micro displacement mechanism. So it can not only take the simple structure, fast response, self-locking and high resolution advantages of the motor, but also realising scaling and improve stiffness. Then after building electrical system, power supply and communication links between ACS controller, AB1A drive and other electrical components was realized. A closed-loop control system was built by taking grating signal as feedback.Secondly, this paper carried out the study of the control algorithm for the drive system. On the basis of fully analyzing the features of ultrasonic motor, using system identification for system modeling, and put forward the double grating compound closed-loop control combined with feedforward control. But as the ultrasonic motor has nonlinear, time-varying and difficult to establish accurate mathematical model features, the appeared similar overshoot phenomenon when reversing and situation of load change, traditional PID is can’t meet the control requirements. So a fuzzy PID controller was designed as fuzzy control does not require the accurate model of controlled object and its adaptability is strong. But once the parameters of fuzzy controller was chosed, they cannot be changed which will lead to unable to adapt parameters automatically for wide ranges. In this paper, genetic algorithm was used to optimise the quantization and scaling factor of the fuzzy PID controller. Simulation researches are carried on to indicate that the controller has a good performance.Finally, in the dynamic stiffness test based on the special wedge drive mechanism, we found that the stiffness is much higher than direct driving platform, meeting the design purpose. In addition, we did the location accuracy comparison experiment based on control algorithms and interface that developed on the.NET platform. The result turns out that the axial positioning accuracy can reach 1 μm, which is much better than direct driving platform. In the validation experiments of Fuzzy PID control effect, it was proved that the fuzzy PID controller design had better control characteristics than traditional PID control.