An Energy-Saving Control Strategy with Load Sensing for Electro-Hydraulic Servo Systems

The electro-hydraulic servo system (EHSS) has been demonstrated to be a promising choice for diverse applications due to its high-power density, ease of implementation, good dynamic performance and durability, despite the rapid development of electric power transmission. Owing to these characteristic, the EHSS has been widely used in the aircraft control, machine tools and manufacturing, excavating, and automotive industries [1] to [4]. The problem of EHSS position tracking control has been addressed in many papers and numerous methods have been proposed to improve the position tracking control performance of the EHSS. To be specific, in [5], an extended disturbance observer is presented to achieve the position-tracking task for its fast response speed in handling the disturbance. An adaptive robust controller (ARC) has also been utilized for the trajectory tracking of hydraulic actuators in the presence of uncertain nonlinearities and parameter uncertainties [6] and [7]. A feedforward plus Linear Quadratic Regulator (LQR) controller and quantitative feedback controller (QFT) were proposed in [8] and [9], respectively, to improve the robustness of the EHSS. A compound control strategy based on velocity compensation and active disturbance rejection control was proposed in [10] to enhance the system’s anti-jamming capability while simultaneously improving the control precision of the system. Although the aforementioned methods have been demonstrated to be successful for their specific purpose, the EHSS is not among the most efficient actuation methods from an energy-saving perspective, which may limit its further applications in industrial and machinery contexts. Therefore, certain efforts have been made in the literature to improve the overall efficiency of the EHSS. An integrated control of clamping force and energy saving by using a load-sensing variable pump was proposed in [11]. The electrical adaptations of this method, electro-hydraulic load sensing (EH-LS), which includes a constant displacement pump and an AC motor, was also utilized to improve the energy efficiency of the EHSS [12] and [13]. However, the pressure difference across the valve, which is usually set at a constant value, is not optimized from an energy-saving perspective. Thus, the efficiency of the load-sensing pump could be further improved by reducing the pressure loss across the valve [14]. As an alternative, energy regeneration is also an attractive research field for energy saving of EHSS [15] and [16]. Specifically, in [16], the independent valve metering control method for a hydraulic manipulator using five cartridge valves and one accumulator was proposed. However, although a significant energysaving capability was obtained, the energy loss in the cartridge valve is still considerable. It is clear that although a certain amount of energy can be saved by the aforementioned methods, system An Energy-Saving Control Strategy with Load Sensing for Electro-Hydraulic Servo Systems Wang, W. – Wang, B. Weiping Wang1,2,* – Bo Wang1 1 School of Mechatronic Engineering, China University of Mining and Technology, China 2 Jiangsu Key Laboratory of Mine Mechanical and Electrical Equipment, China University of Mining and Technology, China