Exploring Vehicle Lateral Motion Limit: Neutral Steering Control for Dual-Motor All-Wheel-Drive Electric Vehicles

Maximizing the utilization of lateral motion limits can significantly enhance vehicle safety under extreme driving conditions. This paper presents a neutral steering chassis coordination control scheme to extend the lateral motion limits of Dual-Motor All-Wheel-Drive Electric Vehicles (DMAWD EVs). First, an optimization model is developed using the tire friction ellipse to determine the maximum lateral force. It is demonstrated that a vehicle can fully exploit its lateral motion limits under neutral steering. Then a driving torque allocation method for the front and rear axles and a sliding mode control method for the electro-hydraulic composite anti-lock braking system are designed to fulfill the driver’s driving intentions under normal driving conditions. In extreme driving conditions, a torque vectoring control strategy is proposed to coordinate the motors’ driving torques and the hydraulic braking forces, while a Smith predictor-based control scheme is introduced to enhance the hydraulic braking responsiveness. Furthermore, a coordinated pitch and roll attitude controller is developed to maintain neutral steering. Finally, the proposed control scheme is verified through comprehensive testing on a Hardware-in-the-Loop platform. Results indicate that the maximum lateral acceleration increases by 18.14% under the open-loop sine steering scenario. The proposed control scheme renders DMAWD EVs to have comparable performance with four-wheel-independent-drive electric vehicles.