Optimal Energy Consumption and Response Capability Assessment for Hydraulic Servo Systems Containing Counterbalance Valves

Counterbalance valves (CBVs) are broadly applied in hydraulic manipulators, which is essential to ensure safe operation while moving a heavy load. They inevitably introduce additional energy consumption and poor dynamic performance. For the manipulator joint in tunnel boring machines, smooth and precise motion control has to be realized. However, for the forward design considerations, in this case, no systematic work has been done to determine the component parameters based on an energy-saving approach and to derive the natural frequency of the joint at the hydraulic level. To fill this gap, this paper proposes a forward design approach for the proportional valve-controlled hydraulic cylinder system containing CBVs, which is a basic hydraulic configuration adopted for the manipulator joint. Specifically, the optimization model aiming at the minimum energy consumption is defined and improved to solve the key parameters, including the pilot ratio of the CBV and the area ratio of the cylinder. By considering constraints, the other component parameters could be further calculated. After that, the theoretical derivation of natural frequency is given to evaluate the response capability of the system. The overall design procedure is presented to determine the cylinder, CBV, control valve, and constant pressure supply. Based on the validated numerical model, the energy-based design principle is proven effective and could ensure that energy saving is not less than 5% and not more than 36% on average. Furthermore, the natural frequency obtained by the sweep test is verified to be consistent with the theoretical value, and the impact of this parameter on control performance is analyzed. The results indicate that the proposed approach has an excellent guide for the forward design of such systems.