基于LQR的四轮转向汽车控制方法

用选定的加权系数将轮胎较大侧偏刚度和轮胎较小侧偏刚度的车辆状态方程关联起来,并应用了线性二次型最优控制理论(LQR)设计了综合考虑轮胎非线性特征的四轮转向线性二次型最优综合控制算法;用Matlab/Simulink和Carsim建立了联合仿真模型对所设计的控制算法的控制效果进行了验证. 仿真结果表明:在低附着系数路面进行车道变换行驶时,基于定轮胎侧偏刚度LQR线性控制的四轮转向汽车与前轮转向汽车相比具有更加优越的操控性能;基于非线性轮胎侧偏刚度LQR权系数控制的四轮转向汽车比定轮胎侧偏刚度LQR线性控制的四轮转向汽车要有较好的操控性能. 

The Control Method About Four Wheels Steering Car Based on LQR Theory

In this article, the bigger tire cornering stiffness and the smaller tire cornering stiffness were connected with the weighted functions to synthesize a nonlinear equation of state of vehicle. The optimal theory of linear quadratic regulator was used to design a synthetic controller to control the four wheels steering car, considering the nonlinear character of tire cornering stiffness. The software of Matlab/Simulink and Carsim were used for a co-simulation to test the performance of the controller. The results of the simulation show that, when the car is carrying out a double lane change on the low adhesion coefficient road, the four wheels steering car controlled by LQR method can give a better handling performance than front wheels steering car, and the four wheels steering car controlled by LQR synthetic controller which considers the non-liner tire stiffness can give good handling performance than LQR controller which considers only the liner tire stiffness.