An adaptive control system with self-organizing fuzzy sliding mode control strategy for micro wire-EDM machines

Abstract

This paper aims to develop an adaptive control system for process monitoring, identification, and control in micro wire electrical discharge machining (wire-EDM). The proportion of short circuits in the total sparks defined as short circuit ratio is chosen as a control parameter for the adaptive control system. Pulse interval of each spark is adjusted in real-time according to the discrimination of gap status to improve the stability of machining operation. A self-organizing fuzzy sliding mode controller is then proposed for servo feed control. This intelligent control strategy has on-line learning capability and disturbance rejection robustness for responding to the nonlinear, stochastic, and time-varying characteristics of the micro wire-EDM process. Another fuzzy logic controller is designed to control the short circuit ratio at a pre-determined level through an on-line regulation of servo voltage for adaptive process control. Experimental results show that the developed adaptive control system results in faster machining and better machining stability than does a conventional control scheme.