Implementation of a fast path planner on an industrial manipulator

Abstract

A fast path planner is implemented on a SUN Sparc workstation that controls a Puma 560 manipulator. Path planning is achieved by decomposing the robot configurations into body formations and arm postures, and a two-phase path planning procedure. In the off-line planning phase, the defined formations and postures are generated, and a two dimensional collision table is set up, while in the online planning phase, a graph search is carried out to find a sequence of adjacent collision free formations and postures. The software for implementation of the path planner consists of several main modules for configuration generation, link volume modeling, obstacle data base, collision table, graphic simulator, robot interface and path finder. Extensive tests involving several thousand trial have been carried out in an environment cluttered with complex shaped obstacles such chairs, computer terminals and pipelines. The planning time and planning success rate are determined experimentally for different resolutions. The path planner finds and executes a collision free path in nearly all cases where such a path exists. The path planner is fast, and the online planning time is a couple of seconds on the average for a modified Puma 560 working in an environment containing some twenty complex shaped obstacles.