Normal direction measurement based on 3D point cloud in robotic drilling

In large-scale assembly, the perpendicularity of bolting fastens is very critical for the fatigue life and fluid dynamic configuration of the drilled surface. Because the deformation from assembly stress and workpiece manufacturing error, the profile of the prepared drilling surface is different from the CAD model, so the on-line normal direction measurement is required instead of extracting from the CAD model. In this article, a robust normal direction measurement method in robotic drilling based on point cloud is proposed. In our method, the structure-light-based 3D sensor is used for acquiring the surface 3D point cloud and then the modified PCA is applied for calculating the drilling normal direction. The process for aligning the robotic drilling device to the measured surface is also studied. The proposed method is verified by several simulations experiments. The result show the methods are robust and effective.