Optimal grey-fuzzy controller design for a constant turning force system

In this paper the grey-fuzzy control scheme is proposed to control the turning process with constant cutting force under various cutting conditions. The grey-fuzzy control scheme consists of two parts: the grey predictor and the fuzzy logic controller. When we use the grey-fuzzy control scheme to design the constant turning force system, it is necessary to adjust the control parameters of both the grey predictor and the fuzzy controller (i.e., the sample size and grey constants of the grey predictor, and the scaling factors of the fuzzy controller) for guaranteeing stability and obtaining optimal control performances. Therefore, in order to search for the optimal control parameters by way of systematic reasoning instead of the time-consuming trial-and-error procedure, in this paper the Taguchi method is applied to search for the optimal control parameters of both the grey predictor and the fuzzy controller such that the grey-fuzzy controller is an optimal controller. Computer simulations are performed to verify the effectiveness of the above optimal grey-fuzzy control scheme designed by the Taguchi method. It is shown that satisfactory performances have been achieved by the optimal grey-fuzzy control scheme designed in this way. (C) 2002 Elsevier Science Ltd. All rights reserved.