Application of self-tuning fuzzy PID controller for a SRM direct drive volume control hydraulic press

A new kind of volume control servo hydraulic press driven directly by Switched Reluctance Motor (SRM) is presented in this paper. In considering the saturation and dead zone nonlinearity as well as the time-variability and the time lag existed in SRM direct drive volume control system, a fuzzy PID control method is introduced to improve the overall performance of the electro-hydraulic position servo system. The relationships between the PID parameters and the response characteristics of electro-hydraulic position servo system are investigated. The fuzzy inference rules which enable adaptive adjustment of PID parameters are established based on the error and change in error. The simulations and experiments of step response and cosine tracking are carried out on the SRM direct drive hydraulic press. The results indicate that the fuzzy self-tuning PID method has great ability of restraining external disturbance, and it can effectively raise the position tracking ability of the volume control electro-hydraulic servo system.