The Research On Control Strategy Of NC Machine Tool Position Servo System

The servo performance of NC machine position servo system is determined by its dynamic and static characteristics. So the control strategy adopted by the position servo system directly affects the overall performance of the CNC machine tool. In order to improve the response characteristics of NC machine tool position servo system, through consulting relevant literature and analyzing existing control strategies such as PID control and sliding mode control, the switching fuzzy adaptive sliding mode algorithm is put forward and the adaptive fuzzy sliding mode controller is designed based on the Lyapunov. The stability of this servo system based fuzzy sliding mode controller is proved via Lyapunov analysis. Finally, the effectiveness and superiority of the switching fuzzy adaptive sliding mode control algorithm are verified by the MATLAB/Simulink pure simulation software and the semi-physical simulation platform based on AD5435.Firstly, through in-depth understanding of CNC machine tool servo system, permanent magnet synchronous motor mathematical model and tricyclic driving model of CNC machine position servo system based on SVPWM control are built. The establishment of tricyclic mode laid a theoretical foundation for the research of servo control strategy.Secondly, PID control algorithm and sliding mode control algorithm are respectively applied to NC machine tool position servo system, the corresponding models of both algorithms are built and the simulation experiment is carried out in the environment of MATLAB/Simulink. The advantages and disadvantages of these two control strategies is analyzed via experiment results. To solve the chattering problem of sliding mode control, this paper proposes a switching fuzzy adaptive sliding mode algorithm. This algorithm is faintly close to the switching item of control law in sliding controller via adaptive fuzzy control method and realize the serialization of switching item. Through Lyapunov stability analysis, parameter adaptive laws is designed and the stability of servo system based on switching fuzzy adaptive sliding mode control algorithm is proved. Theoretical analysis and simulation experiments verify the switching fuzzy adaptive sliding mode control algorithm can solve the chattering problem and can guarantee the system robustness in the meantime.Finally, in order to furtherly validate the superiority and effectiveness of the proposed switching fuzzy adaptive sliding mode control algorithm, semi-physical simulation experimen-tal platform based on AD5435 is built. The three control strategies such as PID control, the common sliding mode control and switching fuzzy sliding mode adaptive control of semi physical simulation are respectively carry on semi-physical simulation experiment. Experime-ntal results show that the switching fuzzy adaptive sliding mode control algorithm not only overcome the drawbacks of conventional sliding mode control, but also effectively reduce the system chattering, this control algorithm has strong robustness for the system disturbance and load changes and can improve the stability, rapidity and accuracy of CNC machine tool position servo system.