Research On Tracking Control Strategy Of Piezoelectric Ceramic Fast Tool Servo System

In recent years,the field of ultra precision machining has attracted much attention because of its irreplaceable.Ultra precision machining parts such as optical free-form surface are widely used in national defense,medical treatment,electronics and other fields with the advantages of small size,high precision and good physical properties.As one of the core technologies of ultra precision machining,the design of fast tool servo(FTS)has a great influence on machining accuracy.In this thesis,the trajectory tracking of the piezoelectric ceramics driving FTS under high-frequency response and periodic signal inputing system is studied.The main work is as follows:Firstly,the principle and control algorithm of FTS using piezoelectric ceramic is studied by searching literature.On this basic,the mathematical model of FTS is established.Secondly,Considering that most of the FTS work in the state of high frequency response and periodicity,as well as the influence of hysteresis and creep characteristics of piezoelectric ceramic materials on the system,the iterative learning algorithm is adopted.Iterative learning control method has good tracking effect for periodic signal,and also has obvious suppression effect for periodic disturbance.But iterative learning has slow convergence speed,it’s solved by sliding mode control,and the fuzzy control is introduced to reduce the chattering problem of sliding mode control.This way can improve the accuracy of tracking and anti-interference ability of the system,through the MATLAB / Simulink simulation and compared with the traditional iterative learning controller,the effectiveness of the proposed control strategy is verified.Finally,aiming at the disturbance of non periodic signals such as cutting force to the system,the fuzzy sliding mode iterative learning control method based on exponential convergence disturbance observer is adopted to improve the machining accuracy of the system and achieve the purpose of ultra precision machining.The disturbance of the system is observed by the disturbance observer,and the observed disturbance is feedforward to the control law of the controller to compensate the disturbance.Then the simulation is carried out by Matlab /Simulink.Simulation results verify the effectiveness of the proposed composite control strategy.