Research On Short-wavelength Track Irregularity Detection Technology

Railway is developing towards the direction of high speed and heavy load.The safety and comfort of railway are widely concerned,which are closely related to the track regularity.Track irregularity is the main cause of train vibration,which aggravates the dynamic effect of wheel and rail,reduces the ride comfort,accelerates the damage of vehicles and track parts,increases the maintenance cost,and seriously endangers the traffic safety.Short-wavelength irregularity is an important manifestation of track irregularity,which requires stable and efficient detection methods and techniques.This paper analyzes the current situation of short-wavelength irregularity detection at home and abroad and the principle of common detection methods.Combined with real-time detection requirements,a set of short-wavelength track irregularity detection system based on inertial reference method is studied.The main research content of this paper is as follows:?1?Sensor selection.According to the requirements of the detection system,through calculation and comparative analysis,the quartz flexible accelerometer was selected for the acceleration sensor,with a frequency response of 50Hz,resolution of1×10^-4g,measurement range of±10g and scale coefficient of 1.0001v/g.The laser displacement meter was selected for the displacement sensor,with a linear range of50mm,an absolute error of 50?m and a resolution of 15?m.?2?Mechanical component design.A new type of sensor mechanical installation component is designed.Displacement meter and accelerometer are installed on the frame of the bogie by fixed support,and reflective plate is installed on the axle box.?3?Analog filter design.To avoid aliasing distortion,a second-order analog low pass filter is used for anti-aliasing filtering of the acceleration signal with a wide frequency band.According to the detection requirements,the circuit parameters are adjusted to design a second-order analog low pass filter.?4?Digital compensation filter design.The amplitude frequency characteristics of the second-order analog low pass filter vary with the train speed.In order to remove the shifting characteristics,a second-order digital compensation filter is designed.The two cascaded to form a second-order hybrid filter to achieve the purpose of removing shift.?5?High pass filter design.This is the focus of this paper,but also one of the innovation of this paper.The design of high pass filter is based on the minimum integral square error criterion and adopts the window function design method.Considering that the real-time detection system needs to adopt simple moving algorithm to realize the detection function,rectangular window and triangular window are more appropriate.In this paper,rectangular window and triangular window are respectively used as base windows to form cascade filter and parallel filter.By adjusting the length and scale coefficient of the base window,the filter of both forms can meet the cut-off wavelength of 3m.The parallel filter is selected through comparative analysis.The high pass filter is composed of a base window and two correction windows in parallel.The base window adopts triangular window.One of the correction windows adopts triangular window,and the other one is composed of two rectangular windows in parallel.?6?Test system verification.Input single sinusoidal wave with different amplitude and wavelength into the detection system,output waveform after filtering,calculate the ratio of output waveform to input waveform amplitude,and draw the transfer function of the system.The superimposed wave with different wavelength components was input into the detection system for filtering,and spectrum analysis of waveforms before and after filtering was conducted.It shows that the amplitude ratio before and after the filtering is consistent with the value of the system transfer function,which proves that the filter achieves the filtering effect and the detection system performs well.?7?Error analysis of detection system.This paper mainly analyzes the error caused by trapezoidal integral method.The relation of data length,detection speed and sampling interval with displacement average error and displacement mean square error was analyzed by control variable method.When the detection speed and sampling interval are constant,the data length is short,and the vibration amplitude of the displacement average error and displacement mean square error is large.With the increase of the data length,the displacement average error and displacement mean square error tend to be stable.When the data length and sampling interval are constant,the detection speed has a certain influence on the displacement average error and displacement mean square error,but the overall influence is small.The displacement average error and mean square error tend to be stable with the increase of the velocity.When the data length and detection speed are constant,the sampling interval has a great influence on the displacement average error and displacement mean square error.When the sampling interval increases,the displacement average error and displacement mean square error increase.