Modeling And Simulation Of Electric-Hydraulic Power Steering System

Electric-hydraulic power steering system (EHPS) studied in this paper is derived fromgear-rack steering device. It is not only good in maneuverability and handing stability,but also in fuel economy as well as electric power steering system, so it is widely usedin automobile and becomes a focus in the research on power steering system.The structure and operating principle of EHPS are studied and the designrequirements are introduced. The straight-line type, polygonal-line type and parabolictype assistance characteristic curves are studied in the accordance with the assistancecharacteristic requirements, the parabolic type assistance characteristic curve is chosenas the object of study, the design method of parabolic type assistance characteristiccurve is introduced and the MAP between running speed, steering torque and assistanceis plotted with MATLAB. In order to get good dynamic and steady property of electricmotor, double closed loop of current and speed is adapted in the PID control. PowerBond Graph Method is introduced, and is used to derived the state pace function ofelectric motor and hydraulic part. The software pack Simulink which is in MATLAB isintroduced, and the simulation model of electric and hydraulic part is established in theaccordance with its state pace function in Simulink, finally through simulation thedynamic properties of electric motor controlled by double closed loop of current andspeed and the hydraulic part is studied. The simulation consequences provide theoreticalbasis for performance analysis and optimization design of EHPS...