Design of Rail Surface Crack-detecting System Based on Linear CCD Sensor

The rail surface crack-detecting system was designed for reducing railway accident due to rail crack. The system adopts linear charge coupled device (CCD) TCD1208AP as image sensor, uses high-speed flash A/D converter AD7821 to collect CCD output video signals, and uses CPLD perform CCD timing generator, A/D converter timing generator, data storage and other control logic. Then DSP executes the image processing, such as noises elimination, edges detection, image segmentation and edges linking, used the improved classical algorithm and morphology algorithm to judge whether the signals are the crack signals or not, and gives display and alarm with sound and light. The whole hardware structure and the software design are introduced in this paper. By experiment, the detecting precision and effectiveness of the system are good for detecting the rail surface crack.