Adaptive fuzzy logic controller for feed drives of a CNC machine tool

Abstract

This paper introduces an adaptive fuzzy logic controller (AFLC) for precision contour machining which adjusts both input and output membership functions simultaneously. The parameters of the proposed controller are self-tuned in real-time according to a continuous measurement of the performance of the controller itself and estimated disturbance values. The adjustment of the membership functions are restricted within a stable range derived from a stability analysis. The proposed controller as well as a conventional fuzzy logic controller and a PID controller were simulated and implemented on a 3-axis milling machine in contour milling. Both the simulations and experiments show that the AFLC can provide superior performance in terms of contour tracking accuracy compared with the other two controllers particularly in machine tool systems where friction is a serious problem in the feed drives.