Development of an Antilock Brake System for Electric Vehicles Without Wheel Slip and Road Friction Information

This paper presents a control method of an antilock brake system (ABS) for electric vehicles. For decades, serious efforts have been dedicated to designing a wheel slip-based ABS controller, but there are some inherent flaws. To realize a robust control system, the wheel slip and road friction information are generally required. Unfortunately, however, these parameters cannot be accurately measured in production vehicles. The method suggested in this paper is aimed at solving these problems by exploiting the nonlinear characteristics of tire force. The optimal wheel slip can thereby be found without wheel slip and road friction information. We employ the motor as an actuator instead of a conventional hydraulic brake system at the front wheels. However, the rear wheels are still hydraulically controlled. That is, the front and rear wheels have different roles in the proposed method. This hardware configuration can be changed for control purposes, so the proposed approach is not designed for a specific hardware configuration. The performance of the proposed method is confirmed by simulations and real vehicle-based experiments.