Aspects of the Energy Consumption of a Digital Hydraulic Power Management System Supplying a Digital and Proportional Valve Controlled Multi Actuator System

Hydraulic motion control is traditionally done with servo or proportional valves. A digital hydraulic valve is based on arrays of simple on/off valves. Independent metering control is possible with digital valves since control notches are not linked together. With commonly used commercial proportional valves constant opening ratios are used. In this paper, a small mobile boom is studied. The lift and tilt cylinders can be controlled with proportional or digital valves. Closed loop control system is based on a robust control method of a multi actuator boom and also inverse kinematic equations are required in coordinate drive. The supply system consists of a Digital Hydraulic Power Management System (DHPMS) which is capable of supplying separate supply pressures for both actuator supply lines. Measurements are done, and one vs. two supply pressures and digital vs. proportional valves are compared. Two different test trajectories and two different load masses are used. Analysis focuses on the energy consumption of different test cases and sources of losses are inspected. Results show that energy consumption can be reduced up to 44%.