Path planning is achieved by a special decomposition of the robot manipulator, an off-line preprocessing stage, and a three phase on-line path planning scheme. The decomposition consists of decomposing the robot into several chains where a chain is a combination of several consecutive links and joints.

Preprocessing is performed by defining a set of postures for each chain, and setting up a collision table which re-integrates the chains into the full robot and stores the collision states of various discretized robot configurations with the obstacles. Path planning using a local search is performed independently in joint subspaces associated with robot chains.

The paths found for the chains are synthesized to obtain a collision-free path for the robot. This decomposition reduces the