Abstract: A hierarchical control strategy for lateral stability based on nonsingular fast terminal sliding mode control is proposed to address the lateral stability problem of distributed-drive electric vehicles under complex working conditions. Firstly, the two-degree-of-freedom reference model of the vehicle is established to obtain the desired yaw rate and the desired side slip angle. Secondly, the upper controller designs a direct yaw-moment control strategy based on nonsingular fast terminal sliding mode control with the desired yaw rate and desired side slip angle as the control objectives, and uses grey wolf optimization algorithm to solve the global optimum of the controller parameters in order to improve the dynamic performance of the system and to ensure strong robustness. Then, based on multiple constraint conditions, a lower-level controller is designed using the quadratic programming method to optimize the torque distribution to each wheel. Finally, in order to verify the effectiveness of the control strategy, simulation experiments on the lateral stability hierarchical control strategy are conducted on the Simulink simulation platform under the sinusoidal rotation angle condition and the double shift line condition. The results indicate that the control strategy proposed in this study can achieve precise tracking of the vehicle′s yaw rate and sideslip angle. Under both sinusoidal steering and double lane change conditions, the overshoot of the yaw rate is optimized by 19 % and 22 %, respectively, while the overshoot of the sideslip angle is optimized by 52 % and 67 %, respectively. This demonstrates that the strategy can effectively control the lateral stability of the vehicle under complex driving conditions, meeting the requirements for vehicle stability control.

Key words: distributed-drive electric vehicle, nonsingular fast terminal sliding mode, grey wolf optimization algorithm, torque distribution