Laser visual measurement for gap values and misalignment values of pipeline welding groove

A laser visual measurement method for values of the gap and misalignment is proposed, when the welding grooves are assembled between pipelines. Firstly, a computer system is designed to realize the automatic detection for the profile of welding grooves. Through the analysis of the collected laser vision images, it is found that the correlative relationship between the values of gap and misalignment and the break point and inflection point of laser stripes. Secondly, the extracted stripe images are processed by skeletal morphology to obtain refined stripes with a single pixel width. The same time, using the sub-pixel contour coordinate detection algorithm, the pixel coordinates of the discrete points on the stripes are obtained. Finally, based on the above-mentioned correlative relationship, the algorithms for the gap values and the misalignment values are established. The actual verification shows that it is feasible to measure values of the gap and misalignment based on the pixel coordinates of feature points in laser stripe, the measurement results can meet the needs of quality assessment in the process of the weld groove assembly