Efficient Collision Detection for Curved Solid Objects

The design-for-assembly technique requires realistic physically based simulation algorithms and in particular efficient geometric collision detection routines. Instead of approximating mechanical parts by large polygonal models, we work with the much smaller original CAD-data directly, thus avoiding precision and tolerance problems. We present a generic algorithm, which can decide whether two solids intersect or not. We identify classes of objects for which this algorithm can be efficiently specialized, and describe in detail how this specialization is done. These classes are objects that are bounded by quadric surface patches and conic arcs, objects that are bounded by natural quadric patches, torus patches, line segments and circular arcs, and objects that are bounded by quadric surface patches, segments of quadric intersection curves and segments of cubic spline curves. We show that all necessary geometric predicates can be evaluated by finding the roots of univariate polynomials of degree at most 4 for the first two classes, and at most 8 for the third class. In order to speed up the intersection tests we use bounding volume hierarchies. With the help of numerical optimization techniques we succeed in calculating smallest enclosing spheres and bounding boxes for a given set of surface patches fulfilling the properties mentioned above.