This thesis presents CNC servo control algorithms and the designing method of controller to reduce the contour error. To design the servo controller, a simple and effective modeling method for machine tools is proposed and PID controller gains are tuned automatically by modified Ziegler Nichols tuning rule using this modeling information. In addition to PID controller, the compensator designed by inverse model is proposed to reduce the contour error caused by servo delay in high speed machining. This compensator produces compensated command to follow original command without servo delay.
In order to test the performance of controller, a 2-axis stage driven by servo motor is designed and a Grid-Encoder is used to measure the contour accuracy. The designing method of controller and experimental result is presented in this paper.
