Research Of The Urban Railway Vehicle Wheel-flats Detection Technology

Urban rail transit is the backbone of the urban public transportation, and is favored in many major cities with its superiorities such as the large volume, safety, rapidity, friendliness to the environment, energy conservation, etc. As the carrier of the urban rail transit, the operation state of the train is directly related to the physical safety and property safety of passengers. Wheel is an importation traveling part of the train and wheel-flat is one of the safety risks during the train’s operation. Therefore, it is part-icularly important to detect wheel-flat and how to diagnose it efficiently and accurately is a well worth studying problem.The study of this thesis stems from "the key technologies of in-transit monitoring and safety warning of urban rail transit" which is one of the state "863"projects and which aims to improve China’s urban rail transit safety level and capability maintenance and to provide the fundamental and global technology and equipment support.Firstly, knowledge of the urban rail transit vehicle was introduced, and the typical failures and their harms of the wheel-flat were analyzed. The vibration acceleration was selected as the major method to detect the wheel-flat based on the contrast of a variety of online testing methods at home and abroad.Secondly, according to the characteristic of the wheel-flat vibration signal, the wheel-flat signal’s features were extracted and the wheel-flat signal was located with the S-transform time-frequency analysis algorithm. Then, the sub-system of wheel-flat detection was designed based on the vibration signal and it was tested with the measured data whose result is very good.Third, to avoid the misjudgment and undetection, the surface roughness of the tread was proposed firstly as the indicator of wheel-flats, and the sub-system of wheel-flat detection was designed based on the laser scattering with the help of the advanced laser technology and optical fiber technology and it was analyzed theoretically and verified feasibly.Finally, specific algorithms of the two sub-systems of wheel-flat detection were given. Therefore a comprehensive detection system was formed with a on-ground system supplemented by a in-vehicle system which improved the efficiency of wheel-flats detection and the reliability of the whole system.