Stable Tracking Control of Autonomous Vehicles at Extreme Conditions

Aiming at the difficulty in ensuring the accuracy and stability of tracking control of autonomous vehicles under extreme conditions, a comprehensive coordinated control scheme for longitudinal and lateral stability is proposed. Firstly the speed of autonomous vehicle under friction limit is planned and the speed tracking under the limit speed is achieved by means of longitudinal acceleration feedforward and state feedback controller. Then a lateral path tracking controller is designed by combining preview feedforward with artificial potential field feedback, and a stability control strategy is proposed based on the deviation of actual yaw rate from desired one, and the driving torque of longitudinal control is optimized. The results of Simulink/Carsim co-simulation show that the proposed comprehensive control scheme for longitudinal and lateral stability can improve the transient response of autonomous vehicles under extreme conditions, restrain the overshoot at the sudden change of road curvature, reduce the steady-state error in path following, and enhance the trajectory tracking accuracy and the lateral stability in the course of curve movement of autonomous vehicles. © 2020, Society of Automotive Engineers of China. All right reserved.