Contour Error Control System Design Of Cnc Machine Tools XY Table Driven By Linear Motor

In the trend of development of CNC machine towards high-speed andhigh-precision, linear motors have been used in CNC machines with its uniqueadvantages of speed and accuracy. and began to replace the traditional servo mechanismcomposed with rotary motor and ball screw gradually. The XY table driven by linearmotor is one of the most fundamental institutions in CNC machines achieve planepositioning and feed, that widely used in CNC boring, milling, drilling, and a variety ofmachining centers.The most important indicators is the contour accuracy CNC machines XY table.The purpose of this study is to design a control system of the workbench for its contourcontrol in the running process of the XY table driven by linear motor, there are a varietyof factors that can affect the operation of the linear motor servo system, and affect thecontour accuracy. Such as load changes, vibration, friction, cutting force change, inaddition, in different process the quality of workpiece is different on the table. qualitychanges will decline the control effect of the control system of linear motor servo, andultimately affect the contour accuracy of the workbench. These factors are issues toconsider in the design of the contour control system.First of all, the article describes the common control method of CNC machine’s XYtable driven by linear motor, and there status and development prospects at home andabroad. expounded the basic structure and working principle of CNC machine’s XYtable. Analyzed and selected a contour control system architecture for this article.Secondly, The paper analyzed the structure of contour control system and thedesign requirements, and established the contour error model. Then, in the requirementsof high-speed and high-precision, established the mathematical model of the CNCmachine’s XY table driven by permanent magnet synchronous linear motor. according tothe characteristics of the linear motor XY table, design the uniaxial speed controller andposition controller.In the process of design controller, this article studied the effect using the PIDcontrol when the quality of the system is changed. Design of the controller for the characteristics that the quality of the system can change in the different operatingconditions. First, using fuzzy control in speed control links and nonlinear PID controlthat improved according to the characteristics of the table, in position control that isbetter compared with traditional PID control on responding to quality changes. Second,on the contour control of the XY table, calculated the contour error of servo feed systemuse the real-time contour error estimation model, useing the Cross-coupling controllerto allocate the amount of the compensation of the X, Y axis. To achieve real-timecompensate on the contour error, improve the contour accuracy of the table.Finally, Completed the modeling and simulation of the control system of linearmotor XY table use the MATLAB/simulink. The results of theoretical analysis andsimulation show that the fuzzy controller and variable parameter nonlinear PIDcontroller used in the XY worktable can maintain good control effect when the systemquality changes in different operating conditions. compared to the two-axis independentcontrol The cross-coupled control can improve the contour accuracy of the table moreeffectively.