Independent Metering/Displacement Control System on Excavator*

Independent control is a promising alternative to the conventional load sensing (LS) system in the construction machinery. The investigations of different independent control layouts, containing independent metering control (IMC) and independent metering and displacement control (IMDC), are performed by taking a specific application - a 2 t mini-excavator. With increased control degrees of freedom (DOF), a three-level pump/valves coordinate control strategy is first designed. Then, energy-saving performances and dynamic characteristics are theoretically analyzed in comparison to the LS system. Typical continuous actions including digging and dumping are simulated using a validated hydraulic-mechanical coupling model of the excavator. The results show that using the proposed independent control system, better controllability can be obtained with higher stability and fast response. Compared with the LS system, the energy-saving ratio for a complete action cycle can achieve 28% and 40% respectively for IMC and IMDC.