ABS Control Algorithm Based on Direct Slip Rate for Hybrid Brake System 2018-01-0830
The brake-by-wire system (BBW) is better match the new energy vehicle in the future direction of development. The electro-mechanical brake (EMB) is lack of the brake failure backup and need a high 42 V voltage for the power supply. This paper presents a new brake-by-wire hybrid brake system (HBS) with the electro-hydraulic brake (EHB) equipped on the front wheels and the EMB equipped on the rear wheels. The combination of these two brake-by-wire systems has advantages of both the EHB and EMB system. The EMB on the rear wheels totally removing the rear pipes and can be simply mounted. In addition, since the need of brake torque on the rear axle is relatively small, the power supply of EMB can be reduced to 12 V. Meanwhile, the EHB on the front wheels has the failure backup function through the hydraulic line. The HBS can quickly and accurately regulate four wheels brake force of vehicles which can well meet the requirement of antilock brake system (ABS). This paper proposes an ABS control algorithm of direct slip rate based on HBS. Firstly, a dynamic model is built up based on the operational principle of HBS. Then, an ABS control algorithm based on sliding mode control is designed. Finally, a hardware-in-loop (HIL) test bench is built to verify the above control algorithm. The HIL experiment result shows that the ABS control algorithm proposed in this paper can ensure the wheel slip rate quickly stabilized near the target slip rate so as to keep the stability of the vehicle.