Hardware-in-the-loop Simulation for an Integrated Braking System

Comparing with traditional braking systems of automobiles, the brake-by-wire (BBW) system has a faster dynamic response and is more suitable for applications that facilitate regenerative braking. As the two main categories of BBW systems, the well-known electro-hydraulic braking system and electro- mechanical braking system are not compact enough and their fail-safe function has always been a worrying aspect. A new BBW system called integrated braking system (IBS) by employing the hydraulic multiplex method was proposed in recent years. The IBS implements power-assisted braking and active braking by means of just an integrated unit. It can certainly be used for ABS, ASR and ESC systems for building up and reducing brake pressure. Presented in the paper is a new structure of IBS, which is mainly composed of a motor, ball screw, master cylinder and four 2/2-way valves. The main parameters of the system and performance requirements of the motor are determined by means of simulation in MATLAB/Simulink. The prototype and controller of the system had been developed, and the hardware-in-the-loop simulation (HILS) test rig was built. Vehicle dynamics model was performed in veDYNA to provide variables such as slip rate and wheel speed to the controllers. The HILS results show that the single wheel cylinder pressure regulation frequency can reach 20Hz. Limited by the performance of the motor, the system can only realize part of ABS functions.