Free space modeling and geometric motion planning under unexpected obstacles

The author addresses motion planning problems for a mobile robot with an incomplete map. For the given start and goal positions, the robot preplans a collision-free path based on the given map, known as the find-path problem. He presents a solution of the find-path problem for the randomly shaped obstacles using an improvement of the retraction method, namely, retraction with local replacement by visibility graph. While the robot is traveling along the preplanned path, unexpected obstacles can appear anywhere and block the passages. On detecting the unexpected obstacles, the robot needs to replan a safe path to maneuver around these obstacles. The author presents three different versions of a motion-replanning algorithm that patch the world model and regenerate a path from the current location to the goal location. In this scheme, he avoids the computation of a completely updated world model by patching the locally updated environment