Fuzzy Controller Design for Positioning and Synchronization of Electrohydraulic System

In this paper, an integrated hybrid design, consisting of two independent sets of cylinder controllers (a feedforward controller and a fuzzy tracking controller) and one coordinate fuzzy controller, is proposed for a dual-cylinder electro-hydraulic lifting system. The system, which is driven by a hydraulic oil supply, is used to achieve a synchronized positioning objective with unbalanced loadings, uncertainties, and disturbances. With the proposed controller structure, motion synchronization commands are generated by a coordinate fuzzy controller. The commands are then dispatched to the cylinder controllers. The two independent sets of cylinder controllers adaptively enforce the position-tracking commands to the individual single-rod actuators. The experimental results verify that the proposed hybrid controller structure can achieve the synchronous positioning objective of two independent, linear electro-hydraulic actuators driven by a single hydraulic oil supply. Meanwhile, the maximum synchronization error of the experimental system can be maintained within plusmn4 mm.