Energy-Saving Trajectory Tracking Control of a Multi-Pump Multi-Actuator Hydraulic System

With the increasing application of automated hydraulic excavators, the demand for high-level control performance and significant energy saving schemes becomes stronger. The traditional hydraulic excavators with single-pump power source have amounts of coupling loss on throttling valves due to multi-actuator effect. Moreover, their operability is usually influenced by the load varying in a large range. This paper proposes a multi-pump system with on-off valve matrix to eliminate the coupling loss by dividing the system into several single-pump single-actuator subsystems. A pump/valve coordinate control strategy with multiple working modes is developed to adapt the load variation. First, mathematical modeling including mechanical part and hydraulic part is carried out based on dynamic analysis. Second, a three-level coordinated control scheme is proposed: 1) The motion tracking level utilizes backstepping control technique with load observation to obtain the desired hydraulic force; 2) The working mode switching level configures the pump and valve control mode to maximize energy saving according to load condition; 3) The force control level utilizes control technique to guarantee the stability and dynamic performance. Finally, comparative experimental results are presented to show the good control performance and significant energy saving achieved by the proposed multi-pump multi-actuator system as well as the control strategy.