理想转向特性对改善车辆操纵稳定性有重要意义.本文中基于LQR最优控制理论,提出了一种新型后轮主动转向变传动比控制策略.首先,综合考虑低速操纵响应性与高速行驶稳定性,建立4WIS电动车理想转向特性;接着根据变传动比曲线设计预期的横摆角速度,并基于LQR最优控制理论提出了主动后轮转向控制策略,以跟踪横摆角速度的预期值;最后,针对典型的双移线工况,进行人车路闭环控制仿真,结果表明,所提出的控制策略较好地实现了理想转向特性.%Ideal steering characteristics have important significance to the improvement of handling and sta-bility of vehicle. In this paper, a novel variable transmission-ratio control strategy for rear-wheel active steering is proposed based on LQR optimal control theory. Firstly with concurrent considerations of low-speed handling respon-siveness and high-speed driving stability, the ideal steering characteristics of a 4WIS electric vehicle are estab-lished. Then, the expected yaw rate is designed according to variable transmission-ratio curve, and by applying LQR optimal control theory, an active rear-wheel steering control strategy is proposed, so as to trace the expected values of yaw rate. Finally, a simulation on human-vehicle-road closed loop control under typical double lane change condition is conducted. The results show that with the control strategy proposed, the ideal steering character-istics can be well implemented.
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