| The relationship of the wheel/ rail contact is the basic research contents in wheel/ rail transportation system. The research on it is of great significance for vehicle performances,derailment mechanism and safety monitoring. And wheel/ rail contact points is the most direct reaction for wheel/ rail contact state. Many scholars in different countries have put much effort into the research on wheel/ rail contact points.When locomotive and vehicle run, track condition and the relative position of wheel and track is also changing.,which makes it difficult installing non-contact measuring sensors to detect wheel/ rail contact points. in view of the wide application of image detection in the area of non-contact measurement, this paper adopt the method of image detection which make the non-contact measurement for the wheel/ rail contact points achieved.First,we get images of wheel/ rail contacting by using CCD camera installed under the bogie of locomotive and vehicle;then make A/D conversion with image grabbing card to change the analog video signal from CCD camera into digital image signal; and then we make smoothed filter to eliminated the noise produced in the process of the image capturing and transmission,as a result,the image quality is improved. The pixels in the edges of wheel/ rail are detected by using edge detection operators to the image that have been filtrated.Usually,the pixels are stray and discrete.Finally,we detect the edges of wheel and rail which is continuous and Single-Pixel's wide by using mathematical morphology processing and edge joint technique.This paper also introduces a approach for camera calibration to calibrate the edge curves of wheel and rail,which can transfer the edge Curves of wheel and rail from image space coordinate to object space's dimension coordinate. Finally,the on-line and continuous measurement for wheel/ rail contact points is realized by calculating the space between wheel eage and rail eage in the image that have been calibrated . |
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