Method and system for identifying welding starting point of three-face angle joint weldment

The invention discloses a method for identifying a welding starting point of a three-sided fillet weldment. The method comprises the following steps: collecting point cloud contour data of a partial section of the three-sided fillet weldment; three-point sampling is adopted to search for a qualified linear model, three sample points are randomly selected from the point cloud data, the distance between any two sample points should be larger than D, and the three sample points are connected in pairs to obtain three linear models; a point cloud merging optimization rule is adopted, the influence of noisy points is reduced, a linear model with the largest number of local points is selected as a main model, the angles between other linear models and the main model are calculated, if the included angles are smaller than a threshold value theta, point cloud data contained in the linear models are merged, and the linear models are estimated again; the welding seam corner point coordinates are converted into a robot c