Research On Tracking Control Strategy Of Piezoelectric Driven FTS

In recent years,diamond ultra precision machining technology of functional surface of precise microstructure is a new technology rising at home and abroad,which is widely used in industrial manufacturing,aerospace and other fields.This technology has not been developed for a long time in China,and the backward processing equipment greatly limits the processing of high-precision micro structure surface optical elements.Therefore,an important task in the field of ultra precision machining is to develop the processing technology of complex micro structure surface.Fast Tool Servo(FTS)is an efficient,high-precision and low-cost machining technology for machining precision micro structure surface,which makes the machine tool have good high-frequency response performance and tracking accuracy.In this master thesis,the piezoelectric ceramic as the driving actuator of the fast tool servo system is studied,and the control strategy under the high frequency periodic signal input is studied.The specific research work is as follows:First of all,after consulting a large number of domestic and foreign literatures about piezoelectric driven FTS,the working principle of piezoelectric driven FTS servo system and the control algorithm of FTS are studied.On this basis,the mathematical model of piezoelectric driven FTS is constructed.Secondly,due to the hysteresis and creep characteristics of piezoelectric ceramic materials,it is difficult to establish an accurate mathematical model for the piezoelectric driven fast tool servo system.Considering the problems of parameter changes in the actual processing,the internal model control method is adopted.The internal model control method is practical,simple in structure,does not need accurate mathematical model,and has few online adjustment parameters,especially for the improvement of anti-interference performance.Due to the hysteresis and creep characteristics of piezoelectric ceramic components,it is difficult to establish an accurate mathematical model,but in the periodic input,the hysteresis can be regarded as the repeated input interference,so iterative learning is introduced to eliminate the repetitive error and make it converge,so as to improve the tracking accuracy of the system.On the basis of internal model control,indirect iterative learning control algorithm is introduced to modify the input of internal model controller,and then to suppress the influence of periodic disturbance.On the basis of theoretical design,mathematical modeling and simulation are carried out,and the feasibility and effectiveness of the proposed control strategy are verified by MATLAB/Simulink simulation.Finally,in order to effectively achieve high-efficiency and high-precision machining of micro structure surface,an indirect iterative learning control method with super spiral disturbance observer is proposed to enhance the system's ability to suppress the aperiodic disturbance.The simulation results show that the control strategy can guarantee the response speed and tracking accuracy of the piezoelectric driven FTS,and has certain anti-interference performance under different amplitude and frequency.