Decoupling Control for nonlinear models of 4WS vehicles with varying longitudinal velocity performance

This paper presents the decoupling control of a nonlinear pitch-bank road 4WS vehicle model. Decoupling conditions of the vehicle model are obtained, which are neither braking too hard that rear wheels leave the ground nor accelerating too fast that front wheels leave the ground. Under these decoupling conditions, the output-feedback control dynamic law and the decoupling result are gained. In the final decoupled system, longitudinal velocity is no longer coupled with lateral velocity or yaw rate, so the subsystem about lateral velocity and yaw rate are typical LPV system, in which parameters are functions of longitudinal velocity. Simulation results show that this decoupling law can improve safety and comfort of the vehicle driving.