Real-Time Stochastic Model and Control of EDM

This paper proposes a new EDM servo control system in which a high speed microcomputer, IBM 386, directly regulates the servo feed speed, instead of servo reference voltage, and takes the parameters of discharge time ratios from an EDEI gap monitor as the feed back signal. The control strategy is developed according to the real-time achieved stochastic model to minimize the variances of the controlled process and increase the machining speed with the control interval time of 2 milliseconds. Extensive experimental investigation shows that with this control method the machining productivity is 15% higher than the values obtained by the model reference adaptive controller when machining small holes and medium size cavities. This control system has been condensed into a simple control circuit and can be implemented on any EDM unit.