Advanced Valves and Pump Coordinated Hydraulic Control Design to Simultaneously Achieve High Accuracy and High Efficiency

The rapid industrial development in the fields, such as robotics and high-tech manufacturing, has put forward much higher requirements for the application of high-performance electrohydraulic system, which should not only achieve high control accuracy but also work in a highly energy-efficient way. As we know, a valve control method could achieve good accuracy, but the low energy efficiency is its essential drawback. Conversely, a pump control method could achieve good energy efficiency, but the achievable accuracy is the drawback. Since neither individual valve control nor individual pump control method can meet the dual requirements, a novel idea of advanced valves and pump coordinated hydraulic control design is developed in this article. Within the control details, the high-performance adaptive robust control law is synthesized to handle the nonlinearities and uncertainties of the electrohydraulic system, and the optimized command generation approach for the valves and the pump is developed to attain the high level of energy efficiency while considering the control performance. Essentially, the control command of the pump is based on the desired model compensation to provide the majority amount of flow in an energy-efficient way, and control commands of the valves are generated directly by tracking errors to guarantee the control accuracy. The theoretical performance of the overall system control design is analyzed. Comparative experiments are conducted, and impressive results are obtained, showing that the proposed system could achieve even better tracking accuracy than the typical valve-controlled system, while the energy efficiency reached a high level. The advantages of the advanced system control design can be verified both in theory and experiments.