Real-time hierarchical stereo Visual SLAM in large-scale environments

Schleicher, David; Bergasa, Luis M.; Ocaña, Manuel; Barea, Rafael; López, Elena
Year: 2010
Type of Publication: Article
Keywords: Mobile robots; Stereo vision; Tracking
Journal: Robotics and Autonomous Systems
Volume: 58
Number: 8
Pages: 991-1002
Month: August
ISSN: 0921-8890
DOI: 10.1016/j.robot.2010.03.016
In this paper we present a new real-time hierarchical (topological/metric) Visual SLAM system focusing on the localization of a vehicle in large-scale outdoor urban environments. It is exclusively based on the visual information provided by a cheap wide-angle stereo camera. Our approach divides the whole map into local sub-maps identified by the so-called fingerprints (vehicle poses). At the sub-map level (low level SLAM), 3D sequential mapping of natural landmarks and the robot location/orientation are obtained using a top-down Bayesian method to model the dynamic behavior. A higher topological level (high level SLAM) based on fingerprints has been added to reduce the global accumulated drift, keeping real-time constraints. Using this hierarchical strategy, we keep the local consistency of the metric sub-maps, by mean of the EKF, and global consistency by using the topological map and the MultiLevel Relaxation (MLR) algorithm. Some experimental results for different large-scale outdoor environments are presented, showing an almost constant processing time.
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