基于CarSim的线控转向汽车理想传动比的设计研究

Research on ideal transmission ratio design of Steer-By-Wire car based on CarSim

为设计线控转向汽车的理想转向传动比,以提高汽车转向时的操纵稳定性,基于Car Sim实车模型进行车辆特性化仿真分析,推导了实际横摆角速度增益的计算公式,以此为基础对线控转向系统的变角传动比特性进行分段研究。中低速段采用定增益法,将遗传算法与汽车操纵稳定性评价指标相结合,优化从方向盘转角到汽车响应的固定横摆角速度增益,以作为中低速段理想传动比的设计依据;中高速段提出将横摆角速度增益与侧向加速度增益按可变权重共同控制的方法设计理想转向传动比。通过Car Sim/Simulink联合仿真,选取双移线实验工况、角阶跃实验工况及稳态加速回转实验工况对控制方法进行验证。实验结果表明,基于所提出的实际横摆角速度增益,采用横摆角速度增益与侧向加速度增益相结合的方法分段设计理想传动比,能够减轻驾驶员的转向驾驶负担,提高汽车转向时的操纵稳定性。

In order to design the ideal steering ratio to improve the maneuverability and stability of steer-by-wire car,the actual calculation formula of yaw velocity gain was established by characteristic simulation analysis of CarSim real vehicle model,and the characteristics of variable angle steering ratio were explored by subsection.At the middle and low speed,fixed yaw velocity gain of steering wheel angle to vehicle response was optimized by genetic algorithm and comprehensive evaluation indexes of vehicle maneuverability and stability to design ideal steering ratio.At the middle and high speed,a comprehensive control method of yaw velocity gain and lateral acceleration gain with variable weight was proposed to design ideal steering ratio.The control method is verified by CarSim and Simulink joint simulation with double line transfer test,corner step test and steady acceleration rotary test.The experimental results show that the ideal steering ratio designed by combining yaw angular velocity gain with lateral acceleration gain calculated by the formula of the actual yaw rate gain can reduce the driver s steering load and improve the steering handling stability.