Research Of 4wis Control Method And Human-Vehicle-Road Closed Loop System

Handling stability, which aims at the research of vehicle's response to driver's command, is one of the key determining vehicle's characteristic and active safeties. This paper takes 4WIS control methods and analysis of human- vehicle-road closed loop system as the study of object. Based on the study of domestic and foreign achievements, each element of 4WIS vehicle model is researched.Firstly, an introduction of 4WID-4WIS EV developed independently by Yanshan University is made. On the basis of vehicle parameters, 4WIS dynamic model is built. Meanwhile, steering system model is built according to theory of system identification, and its PID controller is designed.Secondly, the vehicle control algorithm is designed by using feed-forward plus feedback control which follows the reference model in accordance with optimum control. The model's accuracy and controller's stability and rapidity are testified through simulation, which also shows that 4WIS has great advantages over FWS in the aspects of yaw velocity response and posture maintenance.Thirdly, fuzzy PID control driver model, aiming at tracking the target locus, is deigned according to theory of foresee optimum curvature and algorithm of fuzzy control. Foresee time's influence on locus-tracking is analyzed. Results, gained from simulation of human-vehicle-road closed loop system control, prove that foresee time function can improve the system's locus-tracking quality.Finally, field trail is made to testify the accuracy of vehicle model and driver model.