A Robust Vision Based Weld Center Finding Method In Automatic Ultrasonic Nondestructive Test

The ultrasonic technique has been widely used in nondestructive test and plays a very important role. Keeping the ultrasonic test (UT) heads in a constant position relative to the weld center line is a very important factor that determines the accuracy of automatic ultrasonic nondestructive test system. The existing methods such as using idler wheel or laser projection are very tedious and difficult to operate even for a skilled worker. A novel vision based method to find the weld center is given. Numerous experiments have proven that the proposed vision based method is robust to optical disturbances such as glares, specula reflection or diffuse reflection from the smooth and flat area of the pipe, water, and etc. The automatic ultrasonic nondestructive test system using the proposed method has been successfully used in many petroleum steel pipe plants.