Synchronous motion of two-cylinder electrohydraulic system with unbalanced loading and uncertainties

Abstract

In this paper, an integrated hybrid controller design, consisting of two independent sets of cylinder controllers (including a feedforward controller and a tracking fuzzy controller) and one synchronous fuzzy controller, is proposed for a two-cylinder electrohydraulic system, which is driven by one hydraulic oil supply, to achieve motion synchronization under the various conditions of unbalanced loading, system uncertainties, and disturbances. In the two-cylinder electrohydraulic servo systems, each electrohydraulic actuator not only moves independently but also has individual loading ability, without any mechanical constraint components, between two single-rod actuators. The proposed integrated hybrid controller design first utilizes two independent sets of cylinder controllers to enforce, as adaptively as possible, the position-tracking performance of two individual single-rod actuators. Next, to improve motion synchronization of the two-cylinder electrohydraulic servo systems further during the moving process, the synchronous fuzzy controller is merged with these two independent cylinder controllers to enhance the motion synchronization performance. The experimental results verify that this integrated hybrid control design can achieve the synchronous positioning of two independent, linear electrohydraulic actuators driven by one hydraulic oil supply. Meanwhile, the maximum synchronization error of the experimental system can be maintained within ±4 mm.