Research on the positioning technology of curved weld seam based on laser vision

As the demand for intelligent and autonomous welding becomes more and more extensive, in order to realise the degree of autonomy of welding robotic arm for welding, thus the research of weld seam positioning technology is carried out. The weld positioning system is built by combining the line structured light vision sensor and the robotic arm, and the Gaussian filtering method, Otsu threshold segmentation method and image morphology closed-circuit algorithm are carried out sequentially by acquiring the image of the weld seam light bar, solving the interference caused by the high reflective noise of the welding piece to the narrow weld seam, and obtaining the complete weld seam characteristic topographic information. Determine the scanning speed of 6mm/s, realize the global scanning of the curved weld seam of the non-regular weldment, obtain the pixel coordinates of the light bar image of the weld seam in each frame, assign the value of 0 to the Z coordinate, obtain the linear model of RANSAC, obtain the linear model with the highest number of collected points for feature point extraction, and judge the current frame image, obtain the weld seam centreline position point set and remove the weld seam reconstruction of the workbench. For the extracted non-regular curve weld centreline, NURBS curve interpolation and control of two-point gap straight line interpolation are combined to obtain a smooth and dense complex weld centreline. From the experimental analysis, the error range between the extracted weld centreline and the actual position point in each axis direction is 0.2~0.7mm, which meets the welding positioning accuracy requirements.