Lateral Stability and Torque Optimization Distribution for Distributed Drive Vehicles

To enhance the lateral stability and torque optimization of four-wheel hub motor distributed-drive vehicles under complex road conditions, a hierarchical control strategy for yaw stability is proposed. The upper-layer controller designs a yaw moment controller based on sliding mode control theory, establishing both a two-degree-of-freedom vehicle model and a seven-degree-of-freedom vehicle model to track the vehicle's desired yaw rate, desired sideslip angle, actual yaw rate, and actual sideslip angle. This enables the derivation of the corresponding additional yaw moment. The vehicle's operational state is analyzed using the phase plane method based on the sideslip angle and yaw rate, and the total additional yaw moment is computed through weighted calculations according to the identified state. Simultaneously, an unscented Kalman filter observer is implemented to improve the tracking accuracy of the actual yaw rate and actual sideslip angle in the seven-degree-of-freedom model. The lower-layer controller treats torque distribution as the design variable and allocates torque to each hub motor with the objective of minimizing the tire load rate. Finally, a co-simulation model is developed using CarSim and Simulink, and simulation analyses under double lane change and steering step input conditions are conducted to evaluate the vehicle's lateral stability.