Yaw Torque Control of Electric Vehicle Stability

The 7 degree of freedom (DOF) vehicle model and non-linear tire model were established based on the stability control of the electric vehicle with on-hub motors. Then the stability control strategy based on the yaw torque was presented. The idea sideslip angle at the center of gravity (COG) and idea yaw rate were calculated based on linear 2 DOF vehicle model. The actual sideslip angle at COG was estimated by the state observer. The sideslip angle at COG and yaw rate were selected as the control variables, and the stability controller was designed based on sliding mode theory. The yaw torque which corrected the vehicle driving state was produced by individual wheel driving or braking. The virtual simulation platform of stability control system was established based on CarSim and Matlab/Simulink and the simulation analysis was performed under double lane change. The results have shown that the stability controller could apply the drive force or the brake force rapidly, and control the yaw rate and the sideslip angle at COG accurately and timely. The under steer or over steer of the vehicle has been avoided. The controller keeps the actual track follow the expected track, and has improved the vehicle handle and stability.