Abstract:Low energy efficiency is a significant problem for the hydraulic excavator. To save energy, the independent metering system is a promising alternative to the conventional valve control system by decoupling the meter-in and meter-out orifices. An independent metering control excavator system is a complex hydraulic-mechanical coupling system. In order to build precious simulation model, it is required to identify each component parameter, including the coupling links between hydraulic and mechanical systems. The nonlinear mathematical models of the system were firstly established. The hydraulic model considered both laminar flow and turbulent flow was used to accurately capture the flow-pressure characteristics. The model parameters were estimated according to measurements. The frictions of actuators were also identified by kinetic equations combined with the least square method. In order to increase the accuracy and speed of parameter identifications, the processes of identifications were transformed to a nonlinear optimization subject and a NLPQL multi-objective optimization algorithm was applied to seek the optimal values of property parameters. Based on the mathematical models, a lumped parametric coupling model was presented. Compared with the co-simulation model in the state of the art, the proposed model was implemented in a parametric platform, conducing to improve simulation efficiency because it had the advantages of short computation time and easy to modify mechanical parameters in terms of operating conditions. Finally, experiments were done to compare with the simulation model. The deviation of static pressures in cylinders between simulated and experimental results was less than 0.2MPa, and that of dynamic velocities was about 4%~6.5%. Besides, the results of independent pressure and velocity close-loop control verified that the presented model had enough computation accuracy to provide a reference for researching the control strategy.
