Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001
A follow up to R.A.Brooks [1983] research into the use of Generalized cones for the representation of Free Space, R.A. Brooks [1983] developed a method of path planning for manipulators with 5 or 6 d.o.f. motion. This method is able to solve the pick and place problem in under a minute on an MIT Lisp machine, by approximating the robot as a 4 d.o.f. manipulator. His method is based on the assumption that the world is represented as supported, and suspended, prisms. This method is suggested as a possible precursor for the use of video information about the workcell, from a high level vision system. This has two points of interest; the objects which are suspended from the side will be grossly misrepresented, but this form of encription suits video cameras well. The assumption that the manipulator may be treated as a set of 4 d.o.f. is based on the limitation of the problem to only pick and place operations and insertion (or fitting) operations. This unfortunately means that the objects may only be rotated about the vertical axis when in motion.
The use of Freeways between obstacles allows a choice between alternate paths.
Figure B.5 Freeway Between Blocks
The freeways are basis for maps of joint configurations which are acceptable for motion through these freeways. The methods then find the path using link constraints. This method is described in algorithm form, and the algorithms are quite substantial.