极限工况下自动驾驶车辆转向控制器的设计

Design for the Steering Controller of Autonomous Vehicles at the Limits of Handling

为提高极限工况下自动驾驶车辆的路径跟踪精度并维持车辆行驶稳定性,设计了一种基于线性模型预测控制的路径跟踪转向控制器.该控制器以速度矢量方向角偏差作为控制参考量,在计算过程中以理想质心侧偏角代替实际质心侧偏角,以提高跟踪精度;采用前轮侧向力为控制输入量,并应用仿射近似方法对后轮侧向力进行线性化处理,以减小计算负担.CarSim与Matlab/Simulink的联合仿真结果表明,该控制器能够在轮胎处于附着极限的情况下维持车辆稳定行驶,且跟踪精度较传统控制器有明显的提高.

This paper presents a path tracking steering controller based on the model predictive control（ MPC） that simultaneously minimizes lateral path tracking deviation while maintaining vehicle stability for autonomous vehicles at the limits of handling. To improve the tracking accuracy,the course direction deviation is chosen for refe-rential state,and the steady-state sideslip is used to calculate the course direction deviation instead of using the real-time sideslip. By using the lateral force of front tire as the input of the controller directly,and linearizing the rear tire force by the affine approximation,the computational burden can be reduced. The simulation results on a Car SimSimulink demonstrate that the present controller can operate the vehicle stably at the limits of tire adhesion,and has a better performance in tracking in comparison with the traditional controller.