Research On Key Technology In Track Irregularity Detection System

It is expected that by 2020 China’s railway network could reach a scale of 150,000 kilometers.China’s backbone transport network has already come into being.Rail transit development is gradually converted to long-term safety maintenance and management stage from construction.As the infrastructure of rail transit,rail not only bears the dynamic load of train,but also needs to withstand the influence of natural conditions on it.Using advanced sensing and detection technology to detect rail’s service state in real time and grasping it’s law of state evolution is an inevitable choice for the maintenance and management of railway infrastructure.Especially the appliance basing on laser camera technology in track irregularities,brings about the non-contact measurement of rail.The measurement basing on laser camera technology has the advantage of high precision,large range and active control,which is the inevitable orientation for future development of track detection technology.With the development of advanced sensor technology,high-speed two-dimensional laser displacement sensor(2D)has been widely applied in track detection system,achieving highspeed,real-time and reliable measurement of track.However,the successively improving running velocity of train and the increasing demand for passengers’ comfort poses a greater challenge to the control of track quality.To suffice the railway development and passengers requirement,it needs all researchers continually trying hard to set up a higher precision and more reliable detection system.Track detection system involves many disciplines such as optics,signal processing,computer science,instrument science,electrical engineering and so on.The practical problems need to be solved are very complicated.In order to solve these tough problems,this thesis mainly adopts field test--algorithm optimization--field test research technical route,to study the critical technology in detection system as follows:(1)researching analog and digital mixed filtering technology,functions that track irregularities’ parameters are mileage.Due to the change of detection speed,the spatial sampling signals will form it’s nonuniform sampling sequence.This sequence will go through an analog anti aliasing filter with fixed cut-off frequency,of which the filter characteristics will be shifted in the space domain,causing spatial signals shifted and attenuated.On the basis of the study on the shift and attenuation mechanism,this paper designs de-shift compensation digital filter,therefore the design and calculation formula of arbitrary order shift compensation filter is derived.The function passed by the designed filter is obtained according to the formula.The difficulty of high order shift compensation filter design is solved effectively.(2)Studying error correction and compensation technology in detection system.In detection system,the difficult point for error correction and compensation technology is the detection beam vibration compensation according to the principle of parameter detecting of track irregularity.Based on Kalman filter principle,by establishing observation model of the gyroscope and inclinometer signal on the beam and the state transition model of the detection beam,we track and compensate the roll side vibration attitude of the detection beam.The model is optimized after multiple test and achieving all parameters detection compensated in the system.(3)Studying calculation algorithm for describing the wear degree of rail.At present,calculating rail wear is conducted on the 1/3 top surface and 16 mm beneath the top rail tread.Since the rail wear caused by wheel always exist in certain area,the wear value calculated on this single point is not available to describe the whole rail wear.This paper exactly aims at the deficiency to study rail wear detection algorithm.The concept of rail profile feature curve and smooth filtering algorithm based on median error and continuous adaptively adjustment of weight are put forward.And a new calculating method that is capable of describing the whole rail wear is defined.Finally,applying the research findings above to existing rail detection equipment and relying on detection car hardware devices,the synthetic algorithm software is integrated at back-end.By setting rail deficiencies on the spot the algorithm is verified effective and it has been successfully applied to urban rail transit.