A Novel Method for Laser Peak Detection with Subpixel Accuracy for the Rail Corrugation Measurement

Abstract

In this article, a new wavelet-based laser peak detection algorithm is proposed having subpixel accuracy. The algorithm provides an accurate and rapid measurement platform for the rail surface corrugation with no need to any image noise elimination. The proposed rail Corrugation Measurement System (CMS) is based on the laser triangulation principle, and the accuracy of such system is mainly affected by the laser peak detection in the captured image. The intensity of each row or column of the image is taken as a 1-D discrete signal. Intensity distribution of a laser stripe in this signal follows a Gaussian pattern contaminated by the white noise. Against usual peak detection algorithms with need to prenoise-filtering process, the proposed method based on the wavelet transform is able to perform these tasks efficiently and robustly. Present wavelet-based methods for the peak detection are at pixel level, but for achieving high accuracy subpixel detection is proposed. Experiments show that the capability of the proposed method for laser peak detection is more accurate and faster than the filter-based methods, especially for low S/N ratios. Also, this technique can be utilized for any application in laser peak detection with subpixel accuracy. A prototype system based on the proposed method for the rail corrugation measurement has been designed and manufactured. Results of the rail corrugation measurement guarantee capability of the proposed methodology for accurate measurement of the rail corrugation and its potential for industrial application.

Dynamic diagnosis method and quantitative characterization of rail corrugation

“…When the vehicle runs at a constant speed in a certain section, VL=VH=trueV¯. Set the filtered ABA as {yi},i=1,2,...,N, where N is the length of {yi};b) Calculate the MRMS of ABA, noted as S, its detailed process is similar with the calculation of Track Impact Index (TII) 14 ;c) Divide the S according to track units, and the length of the divided unit is generally 50m;d) Extract the maximum value of the MRMS of each unit, denoted as {Sm,je}, j=1,2,...,Ne, which Ne represents the number of track units;e) Calculate the mean value of Sm,je, which is the calibration parameter …”

“…b) Calculate the MRMS of ABA, noted as S, its detailed process is similar with the calculation of Track Impact Index (TII) 14 ;…”

“…Recently, some new approaches based on computer vision, 13,14 are used on the inspection of rail corrugation. The experimental results show that their methods achieved higher performance in the identification of rail corrugation.…”