Outlier-Robust Long-Term Robotic Mapping Leveraging Ground Segmentation

Despite the remarkable advancements in deep learning-based perception technologies and simultaneous localization and mapping~(SLAM), one can face the failure of these approaches when robots encounter scenarios outside their modeled experiences~(here, the term \textit{modeling} encompasses both conventional pattern finding and data-driven approaches). In particular, because learning-based methods are prone to catastrophic failure when operated in untrained scenes, there is still a demand for conventional yet robust approaches that work out of the box in diverse scenarios, such as real-world robotic services and SLAM competitions. In addition, the dynamic nature of real-world environments, characterized by changing surroundings over time and the presence of moving objects, leads to undesirable data points that hinder a robot from localization and path planning. Consequently, methodologies that enable long-term map management, such as multi-session SLAM and static map building, become essential. Therefore, to achieve a robust long-term robotic mapping system that can work out of the box, first, I propose (i)~fast and robust ground segmentation to reject the ground points, which are featureless and thus not helpful for localization and mapping. Then, by employing the concept of graduated non-convexity~(GNC), I propose (ii)~outlier-robust registration with ground segmentation that overcomes the presence of gross outliers within the feature matching results, and (iii)~hierarchical multi-session SLAM that not only uses our proposed GNC-based registration but also employs a GNC solver to be robust against outlier loop candidates. Finally, I propose (iv)~instance-aware static map building that can handle the presence of moving objects in the environment based on the observation that most moving objects in urban environments are inevitably in contact with the ground.