Handling And Stability Of Four-Wheel Steering Vehicle With Yaw-Rate Trcking Control

Based on the theory of yaw-rate tracking control, a system of four-wheel steering (4WS) is designed for motor vehicle at high-speed with the advantages of economy and reliability. The handling and stability of vehicle is also simulated and analyzed.Firstly, the sideslip characteristics of tire and lateral dynamics of 4WS vehicle are deduced and modeled for simulation. A multi-body dynamics model is also introduced in detail. A H∞optimal control algorithm is proposed for the 4WS vehicle. With the software of Matlab, The handling and stability of conventional front wheel steering (FWS) vehicle is simulated in the domains of time and frequency. The dynamics of sideslip angle, yaw-rate and lateral acceleration is analyzed. A closed-loop system including driver, vehicle and road is built to simulate the handling and stability of 4WS and FWS vehicles. A new method is proposed to evaluate the vehicle dynamics.According to the simulation, the handling and stability performance of 4WS vehicle at high-speed, compared with FWS vehicle, is obviously improved. Driving under different adhesion road and even under limit condition, the handling and stability of 4WS vehicle shows preferable robustness to the nonlinear tire sideslip stiffnessand the road adhesion.