Research On Servo Feed System Of CNC Machines Based On Active Disturbance Rejection Controller Technique

Feed Servo System has a direct impact on the overall performance,indices of CNC machines,an important part of CNC machines,so it is very important to study the high performance servo system for the development of CNC machines industry.There are many factors that influence the performance of Servo Feed System,such as gap error,random signal interference,friction and other so on.They have the random and mutant characteristics which would bring enormous error to Feed Servo System,and trigger a series of the certain constraints and obstacles on the control of the Feed Servo System.Active Disturbance Rejection Control Technique is a control strategy,which can be use to estimate the total interference leaded by system uncertain factors,according to the system input and system,for the purpose of compensation,This strategy does not depend on the specific mathematical model of the controlled system,but the order of the system.In order to process the signal,to get the differential signal,and to filter interference signal,the strategy design Tracking-Differentiator to make it.The(ESO)estimates total disturbance of Feed Servo System and does its best to compensate the disturbance.The error feedback control law is the way to eliminate the feedback error.The parameters of ADRC are easily to be transplanted from one system to another system,and it has been attracting increasing attention for strong robustness,and high control accuracy with uncertainties and disturbances.Firstly,this paper explored dynamic characteristics of the Servo Feed System of CNC machines,established a dynamic equation and decoupled the dynamic system.Secondly,this paper explored the principle of input and output of the Servo Feed system,analyzed the mathematical model of PMSM,studied the vector control methods of PMSM,and studied SVPWM space voltage vector modulation technology.Lastly,this paper explored the principle of each part of the strategy and the relationship between them,optimized parameters of relevant aspects,and the simulation test was implemented.Combined with the mathematical model of PMSM,this research designed a double closed-loop control structure of PMSM speed control system.The second-order ADRC is used in speed-loop,in order to estimate the disturbance of uncertain factors in the system,and then compensate the disturbance.The first-order ADRC is used in current-loop in order to reduce the interference of current loop and stabilize current waveform.The speed control system of PMSM based on PID control used as a comparison system was designed,and simulation was implemented in the environment of Matlab/Simulink.A verification platform,feed controller based on DSP servo and motor drive circuit were designed,to test the speed and current under interference,the correctness and feasibility of the strategy were verified.The control effect of this strategy was compared with the effect of PID control strategy.Experiments show that ADRC strategy has better anti-interference ability and error compensation ability.This study provides a good solution for CNC feed servo-system,and provides reference and thoughts to the application of ADRC used in CNC machines.