汽车四轮转向变增益跟踪控制的研究

A Study on the Variable-gain Tracking Control for the Four Wheel Steering System of Vehicles

在分析车身侧倾对转向系统影响的基础上,对转向系统通常采用的参考模型进行修改,并探讨了轮胎侧偏刚度和车速对参考模型横摆角速度的影响。得出结论为,轮胎侧偏刚度对参考模型的横摆角速度增益有较大影响:前轮侧偏刚度的降低使横摆角速度大致成比例地减小。利用最优前馈和反馈控制方法,提出了四轮转向变增益跟踪控制策略。采用非线性半经验轮胎模型的仿真结果表明,所提出的变增益跟踪控制策略对车辆的操纵稳定性有重大改善。

Based on the analysis on the effects of body roll on steering system, some modifications are made to the reference model commonly used for steering system and the effects of tire cornering stiffness and vehicle speed on the yaw rate of reference model are investigated. It is concluded that the effects are apparent. The reduction in yaw-rate gain is roughly directly proportional to the decrease in front tire cornering stiffness. By utilizing optimal feed-forward and feedback control scheme, the variable gain tracking control strategy for four-wheel steering is put forward, and the results of simulation using nonlinear semi-empirical tire model show that the proposed strategy sig- nificantly improves the handling and stability of vehicle.