PRACTICAL GLOBAL MOTION PLANNING FOR MANY DEGREES OF FREEDOM - A NOVEL-APPROACH WITHIN SEQUENTIAL FRAMEWORK

The sequential framework is a paradigm for developing practical motion planners for manipulators with many degrees of freedom (dof). The essence of this framework is to exploit the serial structure of manipulator arms and decompose the n-dimensional problem of planning collision-free motions for an n-link manipulator into a sequence of smaller m-dimensional sub-problems (with backtracking), each of which corresponds to planning the motion of a sub-group of m - 1 links along a given path. In this article, we present a novel approach within the sequential framework to develop practical motion planners for many-dof arms. In this approach, each sub-problem (m = 2) is solved by using numerical potential fields defined over bitmap-based representations of the 2-dimensional sub-spaces. Furthermore, an efficient backtracking mechanism based on a novel notion of virtual forbidden regions in these 2-dimensional sub-spaces is presented. This approach leads to much more efficient and robust motion planners than a previously reported visibility graph (in the 2-dimensional subspaces) based implementation. We have conducted extensive experiments for arms with up to 8 dof in both 2-D and 3-D workspaces. Although it is not complete, the planner always succeeded in hundreds of simulations with only a few levels (less-than-or-equal-to3) of backtracking. (C) 1995 John Wiley & Sons, Inc.