SENSING FREE-SURFACE OF ARC WELD POOL USING SPECULAR REFLECTION - PRINCIPLE AND ANALYSIS

The weld pool surface provides important information for understanding are welding processes. In this study, a novel vision sensor is propos ed to measure the three-dimensional shape of the free weld pool surfac e. A pulsed laser is projected on to the weld pool through a specific grid. Specular reflection from the pool surface is sensed using a high shutter speed camera. The three-dimensional weld pool surface shape i s clearly shown by the specular reflection. To determine the shape of the pool surface, an image processing technology has been developed to extract the skeleton of the specular reflection fr om the acquired im age. The imaging principle is analysed to determine the correlation be tween the reflection and the weld pool surface. If the weld pool surfa ce is known, the corresponding specular reflection can be directly cal culated using the imaging model which is derived based on the reflecti on law. However, no explicit models can be obtained to determine the w eld pool surface using the reflection and sensor parameters. To solve this difficulty, an iterative algorithm is proposed. The weld pool sur face can now be calculated in 1 second from the specular reflection of the weld pool surface. A higher calculation speed is currently being pursued.