Hybrid Simultaneous Localization and Map Building: a Natural Integration of Topological and Metric

In this paper the metric and topological paradigms are integrated in a hybrid 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 handles loops in the environment during automatic mapping by means of the information of the multimodal topological localization. The system uses a 360° 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 four 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 approach for both the localization and relocation; the fourth type of experiments shows the practicability of the approach for closing the loop.