Rodney A. Brooks
Collision free motions for a manipulator with revolute joints (e.g. a PUMA) are planned through an obstacle littered workspace by first describing free space in two ways: as freeways for the hand and payload ensemble and as freeways for the up-perarm. Freeways match volumes swept out by manipulator motions and can be "inverted" to find a class of topologically equivalent path segments. The two freeway spaces are searched concurrently under protection of constraints determined by motion of the forearm.