A robust wheel slip ratio control design combining hydraulic and regenerative braking systems for in-wheel-motors-driven electric Vehicles

This paper develops a robust wheel slip controller for in-wheel-motors-driven electric vehicles equipped with both hydraulic anti-lock braking systems (ABS) and regenerative braking (RB) systems. Based on a combination of optimal predictive control design and Lyapunov theory, the issue of uncertain vehicle parameters is well addressed. A novel braking torque distribution strategy is also introduced to achieve smooth regulation of the hydraulic pressure, such that pedal pulsating effect of the traditional ABS system can be relieved. By utilizing the larger working range of the hydraulic braking (HB) system and the faster response of the RB system, a better wheel slip control performance can be obtained. Moreover, the torque distributer helps to reach a good compromise between braking distance and the magnitude of the RB torque, which is directly related to the amount of regenerated energy. The effectiveness of the proposed control system has been validated in various simulations.