Research Of Visual Seam Tracking System In The Laser Welding Based On FPGA

Welding seam automatic identification and tracking technology is the principal problem in automatic welding. Among various ways of sensing, structured-light visual sensing technology stands out for its information, sharp accuracy and adaptability.In this paper, the author describes the present situation of welding seam automatic identification and tracking technology. A welding seam tracking system for laser welding controlled by FPGA is designed with a liner CCD sensor and laser diode as assistant lamp-house. This system includes three parts which are optical system, sensor system and pretreatment circuit, image capturing and processing system. The first two consist of information acquisition module and the last one consists of information processing module. This system can track welding seam for laser welding in real-time after improving. The optical system gets seam information by linetype structured-light. The sensor system transforms light signal into voltage signal. The processing system gets the central position of welding seam by some image processing arithmetic, such as the filtering of noise, the product of binary image, threshold detector and so on.Laser emitted by semiconductor laser becomes linetype light through column lens, sending to workpiece with an angle of incidence. Liner CCD changes the optical image of welding seam into video photosensitive signal with pulse driving. After tracking information is magnified and sampled and transformed from A/D, the data is putted into FPGA. The system gets left and right diagnostic edge and central position of welding seam by image processing.Preliminary seaming tracking experiments for laser welding are carried out with the help of the new designed structured-light visual sensing system. The results indicate that the designed welding seam tracking system structure is simple, and can reduce interference and collect welding seam image and position information availably.