<title>Practical motion planners for many degrees of freedom: experimental results and analysis</title>

Abstract

In [Gup90, GG92], we have presented a sequential framework that allows us to develop planners for manipulator arms with many degrees of freedom. 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, each of which corresponds to planning the motion of a sub-group of m-1 links. In this paper, we present extensive experimental results within our sequential framework for a variety of manipulators with up to eight degree of freedom manipulators. Two main goals of these simulations are (1) to show the effectiveness of the sequential approach with the backtracking mechanism, and (2) to quantify the improvement of the backtracking mechanism and the trade-off between number of backtrackings and the execution time of the planner. Our experiments show that the sequential framework with the backtracking mechanism is quite efficient for manipulator arms with many degrees of freedom. For a given maximum backtracking level, the run time and memory requirements vary roughly linearly with the degrees of freedom. The planner succeeds for 91% of the examples in our simulations with a maximum backtracking level of 2. Typical run times for a six degree of freedom manipulator in quite cluttered environments are of the order of tens of minutes. Our sequential thus provides a framework within which practical motion planners for many degree of freedom manipulators can be developed.