Image Detection System and Its Application for Dynamic Wheel/Rail Contact in High Speed Railway

Dynamic wheel/rail contact is the core connecting link between vehicle and track under high speed running condition. Based on optical technology, photoelectric technology, digital image processing techniques and software engineering, a image detection system for dynamic wheel/rail contact is developed. This system is used to get the distribution law of wheel/ran contact points on rail head and wheel tread under high speed running condition. High-speed cameras are placed at the rail's inside and outside. When the train passes the test zone at high-speed, the wheel/rail dynamic contact image can be obtained. A complete wheel/rail contact space trace and contact state are also obtained through process of image feature recognition. The system consists of such hardware as camera imaging and optical unit, image acquisition and storage devices, lighting sources, trigger unit and a image processing software. There is a key step in image acquisition and processing. Image with distortion is restored by the distortion correction function for distortion-free images. Then according to the markers information of calibration parameter, inside and outside part of the corrected image is stitched to form a complete image of wheel/rail contact. This system is verified by laboratory test assembly and field measurement. It can accurately collect clear wheel/rail contact image and qualitatively present the wheel/rail contact state. It can also provide the wheel and rail contour curve and the wheel/rail normal distance of each section. This has provided data support and visual reference for the further study on wheel/rail contact state of high-speed railway.