Direct Yaw Moment Control with 4WD Torque-Vectoring for Vehicle Handling Stability and Agility

Abstract

This paper presents a direct yaw moment control (DYC) for improved lateral stability and agility at severe cornering. A test vehicle was developed for research on highly weighted vehicles such as fully EVs by equipping IWM (In-Wheel Motor) on the front wheels and eLSD (Electronic Limited Slip Differentials) on the rear axle. The control objective is to drive an e4WD system by allocating the torques of four wheels independently. The IWM system on the front wheels provides the agility of yaw behavior, and eLSD on the rear wheels inhibits the yaw behavior at the termination of the turning process. The proposed DYC is composed of a supervisory controller, top-level controller, and bottom-level controller. The supervisory controller determines target behavior based on the desired understeer gradient and desired yaw rate for front and rear torque-vectoring control. The top-level controller calculates a desired yaw moment for the target behavior. The bottom-level controller converts the desired yaw moment to the torque inputs for 4WD torque vectoring. The suggested algorithm was verified through computer simulations and vehicle tests. The vehicle test results present that the integrated control of the front and rear torque-vectoring can improve the handling performance of the test vehicle.