Analysis and Optimization of Minimum Hydraulic Brake-by-Wire System for Wheeled Vehicles Based on Queueing Theory

Based on Queueing Theory, this paper conducts the analysis and optimization of a novel hydraulic brake-by-wire system configuration involving electric-mechanical brake actuators + hydraulic control unit (eActuators + HCU). The functional requirement and topological analysis of frictional brakes are stated. The queueing model is built, providing a theoretical basis to the development of the minimum hydraulic brake-by-wire system involving one eActuator + s valves. Based on the minimum hydraulic brake-by-wire system, the equivalent queueing model is proposed and the evaluation index is defined as average waiting time of wheel cylinder pressure (AWT of WCP). The queueing disciplines are designed and optimized. Integrated-electro-hydraulic brake system (IEHB), a scheme on behalf of the minimum hydraulic brake-by-wire system, is developed and modeled. In accordance to the IEHB physical system, the comparison verifications for the proposed queueing disciplines are conducted via simulations and experiments. The correlation analysis and sensitivity analysis are carried out respectively. Several typical pressure-tracking experiments have been carried out to demonstrate the IEHB control system. This work has two original contributions: 1) The topological and conjoint analysis of the novel hydraulic brake-by-wire system configuration (eActuators+valves) is conducted via Queueing Theory. 2) The performance of the minimum hydraulic brake-by-wire system is improved by using the balanced algorithm, compared with the round-robin scheduling algorithm and rotary control algorithm proposed in the previous study.