Loop Closing in Topological Maps

In order to create consistent maps of unknown environments, a robot must be able to recognize when it has returned to a previously visited place. In this paper, we introduce an evidential approach to the loop-closing problem for topological maps, based on the Dempster-Shafer theory of evidence. In our approach, the robot makes a hypothesis whenever it may have revisited a place. It then attempts to verify hypotheses by continuing to traverse the environment, gathering evidence that supports (or refutes) the hypotheses. We describe methods for managing belief about multiple loop-closing hypotheses, and for determining a belief assignment given a piece of evidence. We also discuss methods for reducing the false alarm rate of our loop-closing algorithm, and provide simulated and real-world experimental results that verify the effectiveness of our approach.