539 research outputs found
Free-Space Features: Global Localization in 2D Laser SLAM Using Distance Function Maps
In many applications, maintaining a consistent map of the environment is key
to enabling robotic platforms to perform higher-level decision making.
Detection of already visited locations is one of the primary ways in which map
consistency is maintained, especially in situations where external positioning
systems are unavailable or unreliable. Mapping in 2D is an important field in
robotics, largely due to the fact that man-made environments such as warehouses
and homes, where robots are expected to play an increasing role, can often be
approximated as planar. Place recognition in this context remains challenging:
2D lidar scans contain scant information with which to characterize, and
therefore recognize, a location. This paper introduces a novel approach aimed
at addressing this problem. At its core, the system relies on the use of the
distance function for representation of geometry. This representation allows
extraction of features which describe the geometry of both surfaces and
free-space in the environment. We propose a feature for this purpose. Through
evaluations on public datasets, we demonstrate the utility of free-space in the
description of places, and show an increase in localization performance over a
state-of-the-art descriptor extracted from surface geometry
CNN for IMU Assisted Odometry Estimation using Velodyne LiDAR
We introduce a novel method for odometry estimation using convolutional
neural networks from 3D LiDAR scans. The original sparse data are encoded into
2D matrices for the training of proposed networks and for the prediction. Our
networks show significantly better precision in the estimation of translational
motion parameters comparing with state of the art method LOAM, while achieving
real-time performance. Together with IMU support, high quality odometry
estimation and LiDAR data registration is realized. Moreover, we propose
alternative CNNs trained for the prediction of rotational motion parameters
while achieving results also comparable with state of the art. The proposed
method can replace wheel encoders in odometry estimation or supplement missing
GPS data, when the GNSS signal absents (e.g. during the indoor mapping). Our
solution brings real-time performance and precision which are useful to provide
online preview of the mapping results and verification of the map completeness
in real time
A Survey on Global LiDAR Localization
Knowledge about the own pose is key for all mobile robot applications. Thus
pose estimation is part of the core functionalities of mobile robots. In the
last two decades, LiDAR scanners have become a standard sensor for robot
localization and mapping. This article surveys recent progress and advances in
LiDAR-based global localization. We start with the problem formulation and
explore the application scope. We then present the methodology review covering
various global localization topics, such as maps, descriptor extraction, and
consistency checks. The contents are organized under three themes. The first is
the combination of global place retrieval and local pose estimation. Then the
second theme is upgrading single-shot measurement to sequential ones for
sequential global localization. The third theme is extending single-robot
global localization to cross-robot localization on multi-robot systems. We end
this survey with a discussion of open challenges and promising directions on
global lidar localization
LocNet: Global localization in 3D point clouds for mobile vehicles
Global localization in 3D point clouds is a challenging problem of estimating
the pose of vehicles without any prior knowledge. In this paper, a solution to
this problem is presented by achieving place recognition and metric pose
estimation in the global prior map. Specifically, we present a semi-handcrafted
representation learning method for LiDAR point clouds using siamese LocNets,
which states the place recognition problem to a similarity modeling problem.
With the final learned representations by LocNet, a global localization
framework with range-only observations is proposed. To demonstrate the
performance and effectiveness of our global localization system, KITTI dataset
is employed for comparison with other algorithms, and also on our long-time
multi-session datasets for evaluation. The result shows that our system can
achieve high accuracy.Comment: 6 pages, IV 2018 accepte
Localization in Unstructured Environments: Towards Autonomous Robots in Forests with Delaunay Triangulation
Autonomous harvesting and transportation is a long-term goal of the forest
industry. One of the main challenges is the accurate localization of both
vehicles and trees in a forest. Forests are unstructured environments where it
is difficult to find a group of significant landmarks for current fast
feature-based place recognition algorithms. This paper proposes a novel
approach where local observations are matched to a general tree map using the
Delaunay triangularization as the representation format. Instead of point cloud
based matching methods, we utilize a topology-based method. First, tree trunk
positions are registered at a prior run done by a forest harvester. Second, the
resulting map is Delaunay triangularized. Third, a local submap of the
autonomous robot is registered, triangularized and matched using triangular
similarity maximization to estimate the position of the robot. We test our
method on a dataset accumulated from a forestry site at Lieksa, Finland. A
total length of 2100\,m of harvester path was recorded by an industrial
harvester with a 3D laser scanner and a geolocation unit fixed to the frame.
Our experiments show a 12\,cm s.t.d. in the location accuracy and with
real-time data processing for speeds not exceeding 0.5\,m/s. The accuracy and
speed limit is realistic during forest operations
View Consistent Purification for Accurate Cross-View Localization
This paper proposes a fine-grained self-localization method for outdoor
robotics that utilizes a flexible number of onboard cameras and readily
accessible satellite images. The proposed method addresses limitations in
existing cross-view localization methods that struggle to handle noise sources
such as moving objects and seasonal variations. It is the first sparse
visual-only method that enhances perception in dynamic environments by
detecting view-consistent key points and their corresponding deep features from
ground and satellite views, while removing off-the-ground objects and
establishing homography transformation between the two views. Moreover, the
proposed method incorporates a spatial embedding approach that leverages camera
intrinsic and extrinsic information to reduce the ambiguity of purely visual
matching, leading to improved feature matching and overall pose estimation
accuracy. The method exhibits strong generalization and is robust to
environmental changes, requiring only geo-poses as ground truth. Extensive
experiments on the KITTI and Ford Multi-AV Seasonal datasets demonstrate that
our proposed method outperforms existing state-of-the-art methods, achieving
median spatial accuracy errors below meters along the lateral and
longitudinal directions, and a median orientation accuracy error below 2
degrees.Comment: Accepted for ICCV 202
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