Parameter Optimization of Servo Drivers and Controller for CNC Machine Tools Based on Grey Relational Approach

Abstract

This paper aims at finding the optimal parameters of the servo drivers and controller for a machine tool in order to improve machining accuracy and reduce machining time. Firstly, the backlash and pitch error of a transmission device were compensated by means of the controller. The control factors of the drivers include the ratio of load inertia moment to servo motor, speed loop gain, and integral time constant of the speed loop. The control factors of the controller are the acceleration/deceleration constant of feed rate and position loop gain. Each factor was classified into three levels and each experiment was repeated three times. The experimental data were converted into the signal-to-noise (SN) ratio to obtain the response tables of the SN ratio. Finally, the grey relational method was applied to find the optimal parameters. We compared the difference of the experimental results by employing the optimal parameters and default values of the drivers and controller of the CNC machine tool. Experimental results show that machining accuracy and machining time can be improved. Therefore, the results demonstrate the effectiveness of the proposed scheme.