The Study And Analysis About Modeling And Control Of Four-wheel Steering Vehicle

The main function of the four-wheel steering is to enhance the handling stability when the vehicle is at a high speed on the against the wind. And the handling light-performance at a low speed can be improved by it, which can reduce the steering radii and make the vehicle safer too. According to the equations of 2DOF four-wheel steering vehicle model, when lateral acceleration and yaw rate to the front wheel steering angle are given, the dynamics simulation can be accomplished according to the control strategies of 4ws. The results of simulation show that the 4ws yaw rate steady state is higher than the 2ws' ,which is much lower than the 2ws' at a high speed. The response time and steady state time of the 4ws vehicles show the same that the 2ws'at either speed. And these also show that the yaw rate is higher than the 2ws' vehicle is steering at low speed. Just in order to analyze totally the structure and nature of the 4ws, the thesis introduces the controlling of the 4wis and makes the model of the 2DOF for 4wis( Four—wheel independent steering, 4wis). Finally, the thesis analyses the 4wis vehicle by the simulation in contrast to the 4ws.