Research On The Compensation Of The Feed Servo System Under The Low Speed

There are a variety of non-linear characteristics seriously affect the performance in feed servo system,such as the friction of kinematic pair under the low velocity,the axial transmission clearances of ball screw nut pair,hysteresis effects and external disturbances and so on.The nonlinear friction is the main reason for the servo system performance.The main content of this paper is how to control methods to reduce the impact of non-linear friction at low speed to improve the performance of the servo system,the main work includes:The mechanical model of nc feed AC servo system including LuGre friction model is established,several important factors that could affect the creeping phenomenon in servo system at low speed are analyzed.Numerical calculation is carried out through Matlab,the influence of the feed servo system parameters on the crawl frequency is analyzed,the main factors affecting the performance of servo system are further determined.The experiments are conducted to obtain data,using state-space equation digital AC servo feed table to identify the parameters of the structural parameters.While the static and dynamic friction model parameters were identified using the method of nonlinear least squares method and the linear approximation processing,and finally errors of the identified results are analyzed.PID+feedforward control compensation scheme is proposed and the related theory analysis is conducted.The Simulink models after supplement are established.In order to verify the effectiveness of PID+feedforward control compensation scheme,different control methods are used,such as PID,feedforward and PID+feedforward.The simulation experiment is conducted on and the simulation results are observed when the input signal is the slope,step and sinusoidal input.The results show that the PID+feed forward control scheme can improve the tracking performance and the positioning performance of the system at the largest degree,which shows the rationality of this solution and provides a theoretical guidance for further practical experimental study.