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

• Published in: Robotics and autonomous systems Vol. 58; no. 8; pp. 991 - 1002
• Main Authors: Schleicher, David, Bergasa, Luis M., Ocaña, Manuel, Barea, Rafael, López, Elena
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 31-08-2010
• Subjects: Consistency; Fingerprints; Mobile robots; Outdoor; Position (location); Real time; Robots; Stereo vision; Tracking; Vehicles; Visual; Mobile robots; Tracking; Stereo vision
• ISSN: 0921-8890; 1872-793X
• 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.