Multi-objective coordinated control for trajectory tracking of autonomous four-wheel drive electric vehicle

Tracking accuracy, lateral stability, and ride comfort are critical aspects in trajectory tracking control, yet they are seldom considered simultaneously. This paper proposes a predictive multi-objective trajectory tracking control scheme to comprehensively tackle these challenges for autonomous four-wheel drive electric vehicle (A-4WD-EV). First, the sideslip angle-sideslip angle rate phase planes are analysed under different driving conditions to construct the lateral stability criterion. This criterion is then refined to be a unified one that incorporates both stability and ride comfort by employing the receiver operating characteristic (ROC) method to classify the data of field tests for ride comfort. Subsequently, a hierarchical multi-objective coordinated control strategy for trajectory tracking of longitudinal and lateral coupling motions of A-4WD-EV is developed. In the upper-layer module, the additional yaw torque and front wheel steering angle are determined based on model predictive control (MPC), where the unified criterion is introduced as a constraint. In the lower-layer module, the torques for four wheels are allocated considering the wheel slip ratio. Finally, co-simulation and hardware-in-the-loop experiments are conducted to evaluate the effectiveness of the proposed method. The results demonstrate that the proposed method enhances vehicle stability and ride comfort while ensuring trajectory tracking accuracy.