Computer Vision Based Method and System for Online Measurement of Geometric Parameters of Train Wheel Sets

Abstract

Train wheel sets must be periodically inspected for possible or actual premature failures and it is very significant to record the wear history for the full life of utilization of wheel sets. This means that an online measuring system could be of great benefit to overall process control. An online non-contact method for measuring a wheel set’s geometric parameters based on the opto-electronic measuring technique is presented in this paper. A charge coupled device (CCD) camera with a selected optical lens and a frame grabber was used to capture the image of the light profile of the wheel set illuminated by a linear laser. The analogue signals of the image were transformed into corresponding digital grey level values. The ‘mapping function method’ is used to transform an image pixel coordinate to a space coordinate. The images of wheel sets were captured when the train passed through the measuring system. The rim inside thickness and flange thickness were measured and analyzed. The spatial resolution of the whole image capturing system is about 0.33 mm. Theoretic and experimental results show that the online measurement system based on computer vision can meet wheel set measurement requirements.

A Novel Online Detection System for Wheelset Size in Railway Transportation

“…Eventually, the error of flange width is = 2 (10) − , where is the original flange width. Theoretically, from (14) and 15, we know that the smaller the value of is, the larger the error is. So, we chose the largest standard wheelset with = 385 mm and = 399 mm.…”

“…This method needed to measure the speed of the train precisely, and the space interval of the points was decided by the speed and the time interval of shooting. Zhang et al [14] used only one CCD camera to capture the image of the light profile of the wheelset, and, in the meantime, the tread profile is illuminated by a linear laser. Overall, the structure of structured laser light and CCD based system seems to be too complex.…”

Development of an On-Board Measurement System for Railway Vehicle Wheel Flange Wear

“…Its construction was not complex and had high stability and precision. The online non-contact measurement of the wheelset wear was also developed and installed on a table fixed near the running rail to avoid some disturbances from vibrations [30]. The images of the wheel profile are captured by the CCD camera together with the optical lens and linear semiconductors laser when the train passes by the device location.…”

Research on influence on luminance of machine vision to measure cotton defects

“…Some methods are put forward based on optoelectronic technology which is nondestructive, and non-contacting, and speedy [3][4][5][6][7][8].…”