Combining Topological and Metric: A Natural Integration for Simultaneous Localization and Map Building

In this paper the metric and topological paradigm are integrated in a single system for both localization and map building. A global topological map connects local metric maps, allowing a compact environment model, which does not require global metric consistency and permits both precision and robustness. Furthermore, the approach permits to handle loops in the environment by automatic mapping using the information of the multimodal topological localization. The system uses a 360 degree laser scanner to extract corners and openings for the topological approach and lines for the metric method. This hybrid approach has been tested in a 50 x 25 m2 portion of the institute building with the fully autonomous robot Donald Duck. Experiments are of three types: Maps created by a complete exploration of the environment are compared to estimate their quality; Test missions are randomly generated in order to evaluate the efficiency of the localization approach; The third type of experiments shows the practicability of the approach for closing the loop.