Weld seam positioning based on CAD model point cloud

With the continuous rise of intelligent manufacturing, pre-weld seam positioning has become an important step in achieving intelligent welding. The method of seam positioning using models can quickly locate the seam information. Firstly, the CAD model of the workpiece is point-cloudified using VTK to obtain the point cloud of the workpiece CAD model, and the seam parameters are picked up using VTK based on the CAD model. Secondly, the registration time is reduced by obtaining the key points of the workpiece point cloud and model point cloud, and the feature descriptors of the key points are used to describe the point cloud features. After rough registration using SAC-IA, the initial pose of the workpiece point cloud and model point cloud is correct. Finally, the workpiece point cloud and model point cloud are registered through iterative closest point matching, and the conversion matrix from the picked model seam parameters to the actual seam parameters is obtained. The registration error is 1.07-1.75mm. The experimental results show that the maximum positioning error after registration is 2.02mm.