Study On The Detecting Technology Of Bridge Cable Surface Defect Based On The Embedded System

Nowadays, Great span bridge are adopted widely in the bridge construction. Especially,the cable-stayed bridge and suspension bridge,with the beatiful structure and better span ability ,are deployed massively in the bridge construction.There are more than 30 cable-stayed bridges which have 200 meters span.As the bearing component, cable is an important part of bridge.Whereas in the service life,it was corroded by rain,sunshine,fog and so on.As a result,the detection of cable is a very important in the healthy testing of bridge.The goal of this dissertion is completing the fast and intellectural detection of cable surface damage.After analysizing the current test technology of the cable surface defect, the paper designed the non-contact detecting method based on embedded system and image recognition,then implemented it technically.Depend on the cable structure characters,the system used concurrent sensor array of 4 CCD to capture the surface image of the bridge cable in real-time and send the data to the DSPs.The DSPs ,based on high-performance processor DM642,includes video signal transform circuit,SDRAM,FLASH interface and so on.The image of bridge cable could be cropped,pretreated,rectified projection,detected and saved.By the characteristics of bridge cable surface image,we designed area cropping to locate processing area,and advanced median filter to denoise.Then,the image could be emendated by the inserting value arithmetic,after that,the target was seperated from background by SOBEL edge detection, dynamic threshold and image morphology sequentially.Finally,the detect recognition arithmetic computed the area of the goal and saved the detect reached the indexes.The system completed real-time and precise detection of cable faults.With low cost,simple structure, easy operation.It is better than manual inspection on efficiency, safety and so,and has important utility value.