基于Carsim和Simulink后轮转向稳定性模糊PID优化分析

Fuzzy PID Optimization Analysis of Rear Steer StabilityBased on Carsim and Simulink

通过对整车操纵稳定性控制目标研究,获得了带后轮转向时,汽车低速、高速后轮正反转向的分界点。推导了比例控制及横摆角速度反馈跟踪控制的计算方法。根据车辆二自由度动力学方程,解决了理想目标对象的建立。通过对反馈误差E和变化误差EC的分析,设计其论域范围及模糊PID控制器。采用Carsim和Simulink联合仿真,由左前轮作为参考输入转角,其它转角用查表方式获取,以角阶跃作评价输入,对建立的模型进行仿真分析。结果表明模糊PID控制器能使汽车在低速、高速时质心侧偏角、横摆角速度得到明显优于前轮转向和横摆角度反馈跟踪控制方式。很好地提升了汽车的操控性能,发挥了后轮转向的低速提供过度转向,高速提供不足转向的优点。

For research on the control target of vehicle handling stability,the cut-off point of the positive steering and reverse steering of the low-speed and high-speed rear wheels of the car with rear steer is obtained.The calculation methods of proportional control and yaw rate feedback tracking control are derived.According to the dynamic equation of two degrees of freedom of the vehicle,the establishment of the ideal target object is solved.Through the analysis of feedback error E and variation error EC,the domain range and fuzzy PID controller are designed.Carsim and Simulink are used for joint simulation,the front left wheel is used as the reference input angle,other input angle are obtained by lookup table,and the angular step is used as the evaluation input,and the model established in this paper is simulated and analyzed.The results show that the fuzzy PID controller can make the car significantly better than the front wheel steering and yaw rate feedback tracking control methods at low speed and high speed.It greatly improves the handling performance of the car,giving full play to the advantages of rear-wheel steering providing oversteer at low speed and understeer steering at high speed.