Side-Slip Control for Nonlinear Vehicle Dynamics by Electronic Differentials

Abstract

Direct control of dynamic variables involved in nonlinear vehicle dynamics is a challenging problem that evolves to new forms along with the proliferation of new vehicular technologies. This paper focuses on one of these variables, the vehicle side-slip. This variable is nonlinearly in tandem with other vehicle dynamic states such as yaw rate, lateral velocity and lateral acceleration. In this paper, these nonlinearities are revisited and a novel electronic differential control method is introduced to adjust the side-slip angle at the smallest possible value. With the new electronic differential on board, the electric car with independent driving motors can achieve a next-to-zero side-slip angle, which significantly enhances the vehicle handling. The proposed electronic differential is implemented in the form of a closed-loop control system that constantly regulates the torque commands sent to the independent driving motors. These commands are generated to tune the differences between the road-tire reaction forces at the amount associated with zero side-slip angle. Comparative simulations manifest that the proposed method outperforms the common equal torque scheme in various challenging steering scenarios.