Accessibility Analysis for Automatic Inspection Using Bounding Volume Hierarchies

The accessibility analysis presented in this paper is based on part discretization and the application of space partitioning techniques (kd-tree) in order to reduce the number of intersection tests between probe and part. The discretization of the part in a set of triangles (STL model) allows the developed algorithms to be applied to whatever part or environment obstacle, independently of their geometry. A recursive ray traversal algorithm has been used in order to speed up the traversal of the hierarchical structure of the kd-tree and to calculate exclusively the intersection of each probe orientation with those part triangles that potentially can interfere with it. In a further step of the analysis, the real geometry of the probe has been considered. For this, a simplified model has been developed for each probe component (column, head, touch probe, stylus and tip) using different basic geometrical shapes. Different models for each probe component have been tested to calculate their intersection with the part, and several algorithms have been implemented to accelerate the computation. Finally, collision-free probe orientations are clustered for minimizing the orientation changes during the inspection process. Furthermore, the applied algorithm allows for determining different valid combinations of clusters.