177 research outputs found
Four years of multi-modal odometry and mapping on the rail vehicles
Precise, seamless, and efficient train localization as well as long-term
railway environment monitoring is the essential property towards reliability,
availability, maintainability, and safety (RAMS) engineering for railroad
systems. Simultaneous localization and mapping (SLAM) is right at the core of
solving the two problems concurrently. In this end, we propose a
high-performance and versatile multi-modal framework in this paper, targeted
for the odometry and mapping task for various rail vehicles. Our system is
built atop an inertial-centric state estimator that tightly couples light
detection and ranging (LiDAR), visual, optionally satellite navigation and
map-based localization information with the convenience and extendibility of
loosely coupled methods. The inertial sensors IMU and wheel encoder are treated
as the primary sensor, which achieves the observations from subsystems to
constrain the accelerometer and gyroscope biases. Compared to point-only
LiDAR-inertial methods, our approach leverages more geometry information by
introducing both track plane and electric power pillars into state estimation.
The Visual-inertial subsystem also utilizes the environmental structure
information by employing both lines and points. Besides, the method is capable
of handling sensor failures by automatic reconfiguration bypassing failure
modules. Our proposed method has been extensively tested in the long-during
railway environments over four years, including general-speed, high-speed and
metro, both passenger and freight traffic are investigated. Further, we aim to
share, in an open way, the experience, problems, and successes of our group
with the robotics community so that those that work in such environments can
avoid these errors. In this view, we open source some of the datasets to
benefit the research community
Learning Local Feature Descriptor with Motion Attribute for Vision-based Localization
In recent years, camera-based localization has been widely used for robotic
applications, and most proposed algorithms rely on local features extracted
from recorded images. For better performance, the features used for open-loop
localization are required to be short-term globally static, and the ones used
for re-localization or loop closure detection need to be long-term static.
Therefore, the motion attribute of a local feature point could be exploited to
improve localization performance, e.g., the feature points extracted from
moving persons or vehicles can be excluded from these systems due to their
unsteadiness. In this paper, we design a fully convolutional network (FCN),
named MD-Net, to perform motion attribute estimation and feature description
simultaneously. MD-Net has a shared backbone network to extract features from
the input image and two network branches to complete each sub-task. With
MD-Net, we can obtain the motion attribute while avoiding increasing much more
computation. Experimental results demonstrate that the proposed method can
learn distinct local feature descriptor along with motion attribute only using
an FCN, by outperforming competing methods by a wide margin. We also show that
the proposed algorithm can be integrated into a vision-based localization
algorithm to improve estimation accuracy significantly.Comment: This paper will be presented on IROS1
Development and evaluation of a dynamically scaled testbed aircraft for a visual inertial odometry dataset
In this thesis we describe the design, manufacturing, and testing of a dynamically scaled aircraft, which is a scaled model of a general aviation vehicle that dynamically behaves in a similar manner as the full-scale aircraft. This scaled model (Cirrus SR22T) is to serve as a testbed for both Distributed Electric Propulsion (DEP) aircraft research and for Visual Inertial Odometry (VIO) research. The aircraft is used as a baseline to compare with the DEP aircraft, to draw conclusion regarding the effect of changing to a DEP configuration, and to provide a way to measure the effect that a DEP configuration would have on a full-scale aircraft. The aircraft is also used to collect data from various onboard sensors to provide a data set for the VIO research community to use
GNSS/Multi-Sensor Fusion Using Continuous-Time Factor Graph Optimization for Robust Localization
Accurate and robust vehicle localization in highly urbanized areas is
challenging. Sensors are often corrupted in those complicated and large-scale
environments. This paper introduces GNSS-FGO, an online and global trajectory
estimator that fuses GNSS observations alongside multiple sensor measurements
for robust vehicle localization. In GNSS-FGO, we fuse asynchronous sensor
measurements into the graph with a continuous-time trajectory representation
using Gaussian process regression. This enables querying states at arbitrary
timestamps so that sensor observations are fused without requiring strict state
and measurement synchronization. Thus, the proposed method presents a
generalized factor graph for multi-sensor fusion. To evaluate and study
different GNSS fusion strategies, we fuse GNSS measurements in loose and tight
coupling with a speed sensor, IMU, and lidar-odometry. We employed datasets
from measurement campaigns in Aachen, Duesseldorf, and Cologne in experimental
studies and presented comprehensive discussions on sensor observations,
smoother types, and hyperparameter tuning. Our results show that the proposed
approach enables robust trajectory estimation in dense urban areas, where the
classic multi-sensor fusion method fails due to sensor degradation. In a test
sequence containing a 17km route through Aachen, the proposed method results in
a mean 2D positioning error of 0.19m for loosely coupled GNSS fusion and 0.48m
while fusing raw GNSS observations with lidar odometry in tight coupling.Comment: Revision of arXiv:2211.0540
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