SELF-TUNING FUZZY CONTROL OF ELECTRO-HYDRAULIC SERVO SYSTEM

Abstract

This study deals with a self-tuning fuzzy controller (STFC) when it is applied to an electro-hydraulic servo system. The STFC has a hierarchic structure consisting of an algorithm being identical to a fuzzy controller at the lower loop, and a tuning algorithm accommodating the performance evaluation and parameter modification function at the upper loop. As an algorithm for tuning at the upper loop, another fuzzy reasoning is adopted for constructing a fuzzy selftuner. The whole procedure of the STFC is repeatedly performed until an acceptable level of control is achieved. The basic functions of the STFC can be summarized as follows:(a) to issue appropriate control action while evaluating the performance, (b) to modify the control action based on the evaluation. It is verified by experiment and digital simulation that the STFC developed in this study is useful and effective for the control of electro-hydraulic servo system.