A Hybrid Displacement/Pressure Control Scheme for an Electrohydraulic Flow Matching System

The electrohydraulic flow matching system is one of the most promising fluid power technologies for the improvement of the control performance and system efficiency of mobile machinery. However, pressure impacts and low efficiencies caused by flow excess are significant drawbacks that hinder its development. To solve this problem, this paper proposes a hybrid displacement/pressure control scheme by utilizing a switching rule according to the pressure margin and the candidate Lyapunov function. The mathematical model of an electrohydraulic flow matching system with primary pressure compensators was established, and the energy efficiency performance was analyzed. Experimental tests in single-actuator and dual-actuator systems were carried out on a test rig with a hydraulic excavator. The experimental results indicated that the pump pressure could be reduced when the supplied flow was excessive, and also the system efficiency was improved. The proposed controller is simple and pragmatic so that it can be easily implemented in the current mobile machinery.