Research on Pressure Control Methods for a Dual-source Electro-Hydraulic Brake System with Redundant Braking Function

This paper presents a novel Dual-source Electro-Hydraulic Brake system (D-EHB) that incorporates a redundant braking module to enhance safety and reliability. The D-EHB is designed to address the critical issue of brake failure in vehicles, which can lead to severe accidents. The D-EHB system comprises two independent units: Main Brake Unit (MBU) and Redundant Brake Unit (RBU). Each unit has its own hydraulic power source. The hydraulic pressure of MBU is generated by a combination of a servo motor, ball screw, and servo piston, while the RBU has a simpler structure, and the hydraulic pressure is generated by a motor and plunger pump combination. Mathematical models for each component of the D-EHB are developed and validated using AMESim. An algorithm for estimating hydraulic pressure of wheel cylinders is developed by mathematical models of each component. The pressure of wheel cylinder is then obtained using the proposed algorithm using output signals of the motor and the valve, so the wheel cylinder pressure can be estimated even if cylinder pressure sensors are not exsted. Given the distinct characteristics of the MBU and RBU, different pressure control methods were proposed. The Sliding Mode Control strategy (SMC) is applied to MBU based on P-V characteristics of servo cylinder, with desired position of master cylinder piston as control output. By using SMC strategy, the hydraulic pressure of the servo cylinder reaches the desired value quickly and accurately, while maintaining robust performance. Proportional control is used for the RBU control based on the overflow characteristics of the solenoid valve. Simulations and bench tests were conducted to compare the pressure control performance of the RBU and the MBU. The results demonstrate that the MBU exhibits excellent control accuracy and fast response speed, while the RBU, although not as precise as the MBU, still meets the braking requirements.