Research On The Underpressure Compensation Control Technologies Of Bus Air Brake System

Air brake system of the bus is one of its critical components about driving safety,underpressure state due to micro-leakage such as the loose joints or micropore of pipeline will seriously affect the braking stability of the bus driving process, and security risks exists. Thesis focuses on underpressure state caused by the micro-leakage, air brake system of bus and its brake control problem are studied deeply, to improve the bus safety performance in underpressure state. The main research work are as follows:(1) Aimed at the failure features and the structural characteristics of bus air brake system, the concept of underpressure brake of bus air brake system is put forward,using the method of theoretical calculations and experimental analysis, the bus driving safety issues brought by bus air brake system in underpressure state is analyzed.(2) Based on the analysis of brake pipeline and main components of bus air brake system, brake pressure characteristic model of bus air brake system in underpressure state due to leakage is built, impact of leakage to brake pressure characteristics of bus air brake system is studied, focusing on the analysis of final stable brake pressure and delay characteristics.(3) Based on the analysis of the braking characteristics and stability control for bus air brake system in underpressure state, the7-DOF dynamic model of underpressure brake control for bus air brake system is built and validated, simulation and analysis are carryied out for braking characteristics of bus air brake system in the underpressure state using the model.(4) Based on the underpressure brake control model of bus air brake system, using differential brake and sliding mode control method, the underpressure compensation control strategy of bus air brake system is put forward, the underpressure compensation controller of bus air brake system is designed to achieve the brake control in the underpressure state.(5) Using the CAN bus control technology, underpressure compensation control network of bus air brake system is designed and its test bench is built, and network performance test is carried out. Targeting a type of bus, using MATLAB/Simulink to simulate and analyze the effect of underpressure compensation control of bus air brake system, the results show that the underpressure compensation control method in this study is effective for braking stability control of bus air brake system in underpressure state.