Robust Tracking Control Of Fast Tool Servo System Driven By Linear Motor

Ultra precision machining parts,like optical free surface parts and micro-structure functional surface parts,etc with its superior qualification are widely used in advanced industrail manufacturing,aerospace,astronomical observation and other high technology areas.Meanwhile,the diamond turning technology based on fast tool servo system(FTS)has become a potential technology to process ultra-precision machining parts for its accuracy,efficiency and low-cost.The critical application of FTS technique is to design a system with high frequency response,accuracy and good signal-tracking performance.By analyzing the design principle of FTS,this thesis mainly focuses on the factors which can affect the function of FTS and the ways to upgrade the system.By comparing and analyzing,this thesis uses ironless permanent magnet linear synchronous motor(ILPMLSM)as an actuator of the FTS system to study on control strategy of given signal with high frequency response.The main research work in this thesis is outlined as follows:Firstly,a large number of literatures about FTS was reviewed,its current development status was mastered.The drive mode and controlling methods of FTS were learned.On this basis,the actuator of FTS—the mathematical model of ILPMLSM is formulates.Secondly,some uncertain disturbances are analyzed in the practice such as parametric variation,friction disturbance and cutting force disturbance.On this basis,the quantitative feedback theory(QFT)is used to design the robust controller to improve the robustness of the system.At the same time,the H∞ control method is used to replace the tedious solution method of drawing in the QFT design to make the process more simplified.Under the guidance of the theory,Matlab/Simulink is implemented to models and simulates the designed control system.The analysis results show that the control strategy can effectively restrain the influence of uncertain disturbances on the operation of FTS system.The robustness of the system is improved.At last,to meet the dual requirements of high robustness and tracking performance of FTS system,the QFT/H∞ with zero phase error tracking controller(ZPETC)and zero magnitude error tracking controller(ZMETC)are combined respectively to design the robust tracking controller.At the same time,the disturbance observer(DOB)is added to the controller to further compensate for the effects of external disturbances on the system and enhance the robustness of the system.On the basic of theoretical design,the simulation results of those two models are compared by Matlab/Simulink.The results show that the designed FTS system has excellent tracking performance and robust performance.