Torque Vectoring Controller of Distributed-Drive Electric Vehicle for Acceleration Slip Regulation and Lateral Stability Enhancement: Design and Test 2020-01-5121

In this paper, a torque vectoring controller is proposed for the distributed-drive electric vehicles to simultaneously prevent loss of traction from excessive wheel slip and enhance vehicle lateral stability. In order to know the expected generation of direct yaw moment for vehicle lateral stability, this study provides two computationally efficient laws for comparisons which are fuzzy logic method and sliding mode method. Besides, a control-oriented model is formulated to describe the plant in mathematics. To satisfy the requirement of direct yaw-moment output and the control input constraints, sequential quadratic programming is adopted to find the optimal distribution for the drive wheel torques aiming at achieving the maximum tire grip margin. Moreover, a proportional-integral controller is designed to compensate the drive wheel torque for the purpose of preventing the excessive wheel slip. Software simulation and in-vehicle experiment were used to test the performance of the torque vectoring controller. Simulation results indicate that the torque vectoring controller with sliding mode method is superior to the torque vectoring controller with fuzzy logic method in improving of vehicle handling and path-following accuracy for distributed-drive electric vehicles. According to the experiment results, this study also points out that the design of the direct yaw-moment law involved in the torque vectoring controller affects not only the vehicle lateral dynamics, but also the vehicle longitudinal dynamics, where the torque vectoring controller with sliding mode method is more responsive to the accelerator pedal position changes. Eventually, experiments validate the effectiveness of the proposed torque vectoring controller in terms of acceleration slip regulation and lateral stability enhancement.