Planning 3-D collision-free paths

In many robot applications, such as assembly and repair operations, the automatic development of collision-free paths is of vital importance. The authors present the results of obtaining such a path with a novel generate-and-test approach, which is both rapid and exact in a three-dimensional, dynamic environment. The approach uses successive spherical approximations (SSA) as a complete model for three-dimensional objects and a path planner which uses rules based on heuristic understanding of the three-dimensional relationships of objects in a known environment. It is shown that the SSA collision detection method can provide marked improvement over direct methods of detecting collisions. The average time required to find collisions with all obstacles along a path as required for path planning in a fairly clustered environment is under 10 s, an improvement over three times compared to a method using face-by-face comparisons