Integrated Chassis Control with Optimal Tire Force Distribution for Electric Vehicles

For a full x-by-wire electric vehicle, an integrated chassis control method is proposed with optimal tire force distribution. The aim is to achieve better performance for vehicle handling and stability. A quadratic programming method is used in the optimal tire force distribution, in which the desired vehicle body forces, including longitudinal and lateral forces and yaw moment, are optimally distributed to all four wheels in both longitudinal and lateral directions. The desired vehicle body forces typically represent driver´s intention and can be inferred from driver´s brake or throttle pedal position, and/or steering wheel position based on a reference vehicle model. Further, a sliding mode control based feedback control is employed to ensure vehicle stability and control robustness to various disturbances, including model uncertainties. In order to verify the effectiveness of the proposed control method, some simulation has been conducted under different driving scenarios with emergency braking on split-μ road surface and for evasive lane changing with braking during high speed respectively. The simulation results show that the proposed control method has greatly improved vehicle limit handling performance and safety under the severe driving maneuvers.