Four Hydraulic Drive Vehicle Model And Control Strategy

Construction vehicle driving dynamics step into a new stage-hydraulic driving dynamics. The research is going to improve vehicles' adaptability under dynamic condition, optimize vehicle's performance and achieve good maneuverability. One pump-four motors independent driving system is the hydraulic driving system indeed. The key content are one variable pump-several variable motors system's structure and control theory under the variable engine rev.The paper shows that one pump-two motors hydraulic driving system of construction vehicle is a multi-input, multi-output system and nonlinear and time-varying plants .The traditional control theory can not work. Aiming at complex nonlinear and variable structure factors, starting from the theory study, the paper simplifies the system to a single-input, double-output system, combines constant-power control method and ideal hydraulic driving control structure, presents a modern integrate control strategy using in the vehicle driving system.The paper analyses the running straightly and swerving conditions of the towing vehicle.According to the variable displacement pump-variable displacement motor system, the nonlinear model of one pump-two motors flow coupling system has been given. Starting from the theory study, the system has been simplified, which has the one motor displacement steps, the constant pump flowing, another constant motor displacement. The paper analyses the system and brings forward an integrate control structure includes several parameters and strong time variables. The paper introduces Fuzzy-PID theory to system, and presents a new control structure which uses Fuzzy-PID as control method. A Simulink model was built in the paper and was running to prove the system's well performance. At last, the paper analyses the coupling parameters in system, and gives the rules of selecting parameters. The research method applying in the paper is suit for other vehicle driving AC systems or modern control systems.