Anti-Lock Braking System Control Design on An Integrated-Electro-Hydraulic Braking System

Two control strategies, safety preferred control and master cylinder oscillation control, were designed for anti-lock braking on a novel integrated-electro-hydraulic braking system (I-EHB) which has only four solenoid valves in its innovative hydraulic control unit (HCU) instead of eight in a traditional one. The main idea of safety preferred control is to reduce the hydraulic pressure provided by the motor in the master cylinder whenever a wheel tends to be locking even if some of the other wheels may need more braking torque. In contrast, regarding master cylinder oscillation control, a sinusoidal signal is given to the motor making the hydraulic pressure in the master cylinder oscillate in certain frequency and amplitude. Hardware-in-the-loop simulations were conducted to verify the effectiveness of the two control strategies mentioned above and to evaluate them. The simulation platform consists of the I-EHB hardware and software including CarSim and MATLAB/Simulink as well as LabVIEW serving as the communication tool. Conclusions can be reached in the light of testing results that both control strategies were able to achieve anti-lock braking under emergency situations. Compared with safety preferred control, master cylinder oscillation control performed better on the functionality of avoiding braking lock and the reduction of braking distance. Also, it is capable of working with electronic stability control systems (ESC) while safety preferred control cannot.