17 research outputs found
Search and Rescue under the Forest Canopy using Multiple UAVs
We present a multi-robot system for GPS-denied search and rescue under the
forest canopy. Forests are particularly challenging environments for
collaborative exploration and mapping, in large part due to the existence of
severe perceptual aliasing which hinders reliable loop closure detection for
mutual localization and map fusion. Our proposed system features unmanned
aerial vehicles (UAVs) that perform onboard sensing, estimation, and planning.
When communication is available, each UAV transmits compressed tree-based
submaps to a central ground station for collaborative simultaneous localization
and mapping (CSLAM). To overcome high measurement noise and perceptual
aliasing, we use the local configuration of a group of trees as a distinctive
feature for robust loop closure detection. Furthermore, we propose a novel
procedure based on cycle consistent multiway matching to recover from incorrect
pairwise data associations. The returned global data association is guaranteed
to be cycle consistent, and is shown to improve both precision and recall
compared to the input pairwise associations. The proposed multi-UAV system is
validated both in simulation and during real-world collaborative exploration
missions at NASA Langley Research Center.Comment: IJRR revisio
SLAM: Decentralized and Distributed Collaborative Visual-inertial SLAM System for Aerial Swarm
In recent years, aerial swarm technology has developed rapidly. In order to
accomplish a fully autonomous aerial swarm, a key technology is decentralized
and distributed collaborative SLAM (CSLAM) for aerial swarms, which estimates
the relative pose and the consistent global trajectories. In this paper, we
propose SLAM: a decentralized and distributed () collaborative SLAM
algorithm. This algorithm has high local accuracy and global consistency, and
the distributed architecture allows it to scale up. SLAM covers swarm
state estimation in two scenarios: near-field state estimation for high
real-time accuracy at close range and far-field state estimation for globally
consistent trajectories estimation at the long-range between UAVs. Distributed
optimization algorithms are adopted as the backend to achieve the goal.
SLAM is robust to transient loss of communication, network delays, and
other factors. Thanks to the flexible architecture, SLAM has the potential
of applying in various scenarios
Near-Optimal Budgeted Data Exchange for Distributed Loop Closure Detection
Inter-robot loop closure detection is a core problem in collaborative SLAM
(CSLAM). Establishing inter-robot loop closures is a resource-demanding
process, during which robots must consume a substantial amount of
mission-critical resources (e.g., battery and bandwidth) to exchange sensory
data. However, even with the most resource-efficient techniques, the resources
available onboard may be insufficient for verifying every potential loop
closure. This work addresses this critical challenge by proposing a
resource-adaptive framework for distributed loop closure detection. We seek to
maximize task-oriented objectives subject to a budget constraint on total data
transmission. This problem is in general NP-hard. We approach this problem from
different perspectives and leverage existing results on monotone submodular
maximization to provide efficient approximation algorithms with performance
guarantees. The proposed approach is extensively evaluated using the KITTI
odometry benchmark dataset and synthetic Manhattan-like datasets.Comment: RSS 2018 Extended Versio
Cooperative SLAM for multiple UGVs navigation using SVSF filter
The aim of this paper is to present a cooperative simultaneous localization and mapping (CSLAM) solution based on a laser telemeter. The proposed solution gives the opportunity to a group of unmanned ground vehicles (UGVs) to construct a large map and localize themselves without any human intervention. Many solutions proposed to solve this problem, most of them are based on the sequential probabilistic approach, based around Extended Kalman Filter (EKF)
or the Rao-Blackwellized particle filter. In our work, we propose a new alternative to avoid these limitations, a novel alternative solution based on the smooth variable structure filter (SVSF) to solve the UGV SLAM problem is proposed. This version of SVSF-SLAM algorithm uses a boundary layer width vector and does not require covariance derivation. The new algorithm has been developed to implement the SVSF filter for CSLAM. Our contribution deals with adapting the SVSF to solve the CSLAM problem for multiple UGVs. The algorithms developed in this work were implemented using a swarm of mobile robots Pioneer 3–AT. Two mapping approaches, point-based and line-based, are implemented and validated experimentally using 2D laser telemeter sensors. Good results are obtained by the Cooperative SVSF-SLAM algorithm compared with the Cooperative EKF-SLAM
OASIS: Optimal Arrangements for Sensing in SLAM
The number and arrangement of sensors on an autonomous mobile robot
dramatically influence its perception capabilities. Ensuring that sensors are
mounted in a manner that enables accurate detection, localization, and mapping
is essential for the success of downstream control tasks. However, when
designing a new robotic platform, researchers and practitioners alike usually
mimic standard configurations or maximize simple heuristics like field-of-view
(FOV) coverage to decide where to place exteroceptive sensors. In this work, we
conduct an information-theoretic investigation of this overlooked element of
mobile robotic perception in the context of simultaneous localization and
mapping (SLAM). We show how to formalize the sensor arrangement problem as a
form of subset selection under the E-optimality performance criterion. While
this formulation is NP-hard in general, we further show that a combination of
greedy sensor selection and fast convex relaxation-based post-hoc verification
enables the efficient recovery of certifiably optimal sensor designs in
practice. Results from synthetic experiments reveal that sensors placed with
OASIS outperform benchmarks in terms of mean squared error of visual SLAM
estimates
SLAM visuel temps réel pour l'estimation précise de plan
National audienceCe papier présente un algorithme de localisation et cartographie simultanée (ou SLAM pour Simultaneous Localization And Mapping) utilisant des contraintes issues de modèles observés dans un environnement inconnu, on parle alors de SLAM contraint ou CSLAM . L'objectif est l'estimation précise des paramètres d'un objet présent dans la scène pour la réalité augmentée. Nous proposons pour cela d'inclure, dans une méthode d'ajustement de faisceaux incrémental, les paramètres de l'objet au même titre que les poses caméras et les points 3D nécessaires au CSLAM . Nous montrons, à travers l'exemple d'un modèle de plan 3D initialisé en ligne, que l'optimisation conjointe des paramètres permet, non seulement de contraindre les points 3D à se rapprocher du plan, mais également de contraindre le plan à se rapprocher des points 3D. Des expérimentations mettront en évidence la précision et le gain en temps de calcul de notre approche comparativement au CSLAM classique
CES-515 Towards Localization and Mapping of Autonomous Underwater Vehicles: A Survey
Autonomous Underwater Vehicles (AUVs) have been used for a huge number of tasks ranging from commercial, military and research areas etc, while the fundamental function of a successful AUV is its localization and mapping ability. This report aims to review the relevant elements of localization and mapping for AUVs. First, a brief introduction of the concept and the historical development of AUVs is given; then a relatively detailed description of the sensor system used for AUV navigation is provided. As the main part of the report, a comprehensive investigation of the simultaneous localization and mapping (SLAM) for AUVs are conducted, including its application examples. Finally a brief conclusion is summarized