Research On Wheelset Tread Scrape Detection Technology Based On Machine Vision

Railway vehicle wheelset as one of the most important inter-changeablecomponents in the vehicle plays key role in the safety of the railway transportation.The scrape of the wheelset tread will cause many problems and impact the safety oftrain transportation. So fast detect the wheelset tread scrape and ensure its wear isunder the limitation have active significance to the safety of the railway transportation.Now, in our country, the wheelset is still measured manually, the method ofmanual detection is mainly detected by mechanical tools manually. This method haslow efficiency, low precision and low reliability. It is also hard to manage the dataautomatically. Through there's some auto measuring equipment in developed countries,such as US, Japan and Germany, they are all expensive and take long times to detect.With the development of the industrial control technology and information technology,the application of machine vision in railway transport meets great challenges.A kind of technology that based on machine vision for automatically detecting thewheelset tread is presented in this paper. The laser is applied to scan the tread surfaceand form different shapes of light stripe while the wheelset is rolling under a certainspeed controlled by step motor. These light stripes are collected by a precise CCDvision sensor. The characteristics of the tread surface can be extracted by analyzing theimages, and a digital matrix that reflects the tread surface profile is also established, bythis, the wheelset tread can be detected and measured instantly.This paper mainly clarifies wheelset tread image pre-processing and analyzingoperators. Wheelset tread image pre-processing improves the quality of image foranalyzing. The following operators are used: median filter, threshold segmentation andCanny edge detection, gray level moment operators for sub-pixel edge location.System gets precise calibration by two-step calibration method and correctingdistortion.Railway wheelset tread automation measurement system adopted visual c++ asmain analyzing and designing programming tool. System works on the Windows 2000 operating system. Many experiments have demonstrated that it works stably. Thedetecting efficiency and the measuring precision of the flats are promoted remarkably.