In this paper, the application of a self-tuning fuzzy control method for electro-hydraulic servo systems is described. As is well known, fuzzy controllers have the ability to control a system in uncertain or un-known environments. However, the control performance depends on the fuzzy rules. Therefore, suitable control rules are required. A self-tuning fuzzy controller (STFC), in which the fuzzy rules for the combination of all input signals are automatically adjusted by the tracking error, has been proposed. Although the STFC is effective for improving the tracking performance, it requires many control rules. To reduce the number of fuzzy rules, the ring- and separate-type STFCs are proposed. In the ring-type STFC, the fuzzy rules are described as a combination of two input signals. The fuzzy rules in the separate-type STFC are used to adjust the gain of each input signal. The effectiveness of the proposed fuzzy controllers for improving the tracking performance is demonstrated by an experiment of boom telescoping axis of an aerial working platform.
