Axle Torque Distribution to Improve Vehicle Handling and Stability

The majority of the fully electric vehicles currently on the market have a basic drivetrain configuration, consisting of multiple electric motors, which promise considerable performance enhancements in terms of vehicle behavior and active safety. A significant advantage was achieving measurable benefits in terms of vehicle cornering response through controlling the individual drivetrains. This paper presents an axle torque distribution method to improve a 4WD vehicle steering performance. The method can automatically adjust the output drive torque of the front and rear motors of the vehicle to change the vehicle yaw rate before ESP intervention, and at the same time remain the driver torque demand unchanged. In this paper we present a feedback yaw rate controller. When the estimated yaw rate differs from the actual yaw rate with a pre-defined small threshold, a yaw rate control is active, the purpose of the controller is to reduce the vehicle understeer characteristic. The simulation and experimental test results shows that this proposed method can reduce the vehicle understeer characteristic and improve the vehicle handling and stability performance.