# TOPOLOGICAL PATH PLANNING – 21138

Topological path planning, also called topological navigation, is a scheme in which a robot can be programmed to negotiate its work environment. The method makes use of specific points called landmarks and gateways, along with periodic instructions for action.

Topological path planning is used by people in everyday life. Suppose you are in an unfamiliar town, and you need to find the library. You ask someone at a small corner grocery how to get to the library. The person says, while pointing in a certain direction, “Go down this street here until you get to the sugar mill. Turn left at the sugar mill. You will pass three traffic lights and then the road will bear left.Keep going around the curve to the left. Just as the curve ends, turn right and follow the bumpy street until you get to a red brick building with white window trim. The building will be on the right side of the road. That is the library. If you get to a large shopping mall on the left, you have gone too far; turn around and go back. The library will then, of course, be on the left-hand side of the road.”

Topological path planning is a qualitative scheme.Note that in the above set of directions, specific distances are not indicated. If you follow the directions, however, you will reach the library, and a computer-controlled robot would find it as well. The instructions, although they do not contain information about specific distances and compass directions, nevertheless provide sufficient information to allow you (or the robot) to find the intended destination.

Topological path planning does not always work. In complex environments, or in environments that change geometry often, more sophisticated navigational schemes are required.