4,101 research outputs found
A Survey of Positioning Systems Using Visible LED Lights
© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.As Global Positioning System (GPS) cannot provide satisfying performance in indoor environments, indoor positioning technology, which utilizes indoor wireless signals instead of GPS signals, has grown rapidly in recent years. Meanwhile, visible light communication (VLC) using light devices such as light emitting diodes (LEDs) has been deemed to be a promising candidate in the heterogeneous wireless networks that may collaborate with radio frequencies (RF) wireless networks. In particular, light-fidelity has a great potential for deployment in future indoor environments because of its high throughput and security advantages. This paper provides a comprehensive study of a novel positioning technology based on visible white LED lights, which has attracted much attention from both academia and industry. The essential characteristics and principles of this system are deeply discussed, and relevant positioning algorithms and designs are classified and elaborated. This paper undertakes a thorough investigation into current LED-based indoor positioning systems and compares their performance through many aspects, such as test environment, accuracy, and cost. It presents indoor hybrid positioning systems among VLC and other systems (e.g., inertial sensors and RF systems). We also review and classify outdoor VLC positioning applications for the first time. Finally, this paper surveys major advances as well as open issues, challenges, and future research directions in VLC positioning systems.Peer reviewe
PRECISE KINEMATIC APPLICATIONS OF GPS: PROSPECTS AND CHALLENGES
GPS kinematic positioning in the post-processed or in the real-time mode is now
increasingly used for many surveying and navigation applications on land, at sea
and in the air. Techniques range from the robust pseudo-range-based differential
GPS (DGPS) techniques capable of delivering accuracies at the few metre level, to
sophisticated carrier phase-based centimetre accuracy techniques. The distance
from the mobile receiver to the nearest reference receiver may range from a few
kilometres to hundreds of kilometres. As the receiver separation increases, the
problems of accounting for distance-dependent biases grows. For carrier phasebased
techniques reliable ambiguity resolution becomes an even greater challenge.
In the case of DGPS, more appropriate implementations such as Wide Area DGPS
become necessary.
In this paper, the challenges, progress and outlook for high precision GPS
kinematic positioning for the short-range, medium-range and long-range cases, in
both the post-processing and real-time modes will be discussed. Although the focus
will be on carrier phase-based systems, some comments will also be made with
regards to DGPS systems. Several applications of kinematic GPS positioning will
be considered, so as to demonstrate the engineering challenges in addition to GPS,
that have to be addressed
AN INTELLIGENT NAVIGATION SYSTEM FOR AN AUTONOMOUS UNDERWATER VEHICLE
The work in this thesis concerns with the development of a novel multisensor data fusion
(MSDF) technique, which combines synergistically Kalman filtering, fuzzy logic
and genetic algorithm approaches, aimed to enhance the accuracy of an autonomous
underwater vehicle (AUV) navigation system, formed by an integration of global positioning
system and inertial navigation system (GPS/INS).
The Kalman filter has been a popular method for integrating the data produced
by the GPS and INS to provide optimal estimates of AUVs position and attitude. In
this thesis, a sequential use of a linear Kalman filter and extended Kalman filter is
proposed. The former is used to fuse the data from a variety of INS sensors whose
output is used as an input to the later where integration with GPS data takes place.
The use of an adaptation scheme based on fuzzy logic approaches to cope with the
divergence problem caused by the insufficiently known a priori filter statistics is also
explored. The choice of fuzzy membership functions for the adaptation scheme is first
carried out using a heuristic approach. Single objective and multiobjective genetic
algorithm techniques are then used to optimize the parameters of the membership
functions with respect to a certain performance criteria in order to improve the overall
accuracy of the integrated navigation system. Results are presented that show
that the proposed algorithms can provide a significant improvement in the overall
navigation performance of an autonomous underwater vehicle navigation.
The proposed technique is known to be the first method used in relation to AUV
navigation technology and is thus considered as a major contribution thereof.J&S Marine Ltd.,
Qinetiq, Subsea 7 and South West Water PL
Context-aware GPS Integrity Monitoring for Intelligent Transport Systems (ITS)
The integrity of positioning systems has become an increasingly important requirement
for location-based Intelligent Transports Systems (ITS). The navigation systems, such
as Global Positioning System (GPS), used in ITS cannot provide the high quality
positioning information required by most services, due to the various type of errors
from GPS sensor, such as signal outage, and atmospheric effects, all of which are
difficult to measure, or from the map matching process. Consequently, an error in the
positioning information or map matching process may lead to inaccurate determination
of a vehicle’s location. Thus, the integrity is require when measuring both vehicle’s
positioning and other related information such as speed, to locate the vehicle in the
correct road segment, and avoid errors. The integrity algorithm for the navigation
system should include a guarantee that the systems do not produce misleading or faulty
information; as this may lead to a significant error arising in the ITS services. Hence, to
achieve the integrity requirement a navigation system should have a robust mechanism,
to notify the user of any potential errors in the navigation information.
The main aim of this research is to develop a robust and reliable mechanism to support
the positioning requirement of ITS services. This can be achieved by developing a high
integrity GPS monitoring algorithm with the consideration of speed, based on the
concept of context-awareness which can be applied with real time ITS services to adapt
changes in the integrity status of the navigation system. Context-aware architecture is
designed to collect contextual information about the vehicle, including location, speed
and heading, reasoning about its integrity and reactions based on the information
acquired.
In this research, three phases of integrity checks are developed. These are, (i)
positioning integrity, (ii) speed integrity, and (iii) map matching integrity. Each phase
uses different techniques to examine the consistency of the GPS information. A receiver
autonomous integrity monitoring (RAIM) algorithm is used to measure the quality of
the GPS positioning data. GPS Doppler information is used to check the integrity of
vehicle’s speed, adding a new layer of integrity and improving the performance of the
map matching process. The final phase in the integrity algorithm is intended to verify
the integrity of the map matching process. In this phase, fuzzy logic is also used to
measure the integrity level, which guarantees the validity and integrity of the map
matching results.
This algorithm is implemented successfully, examined using real field data. In addition,
a true reference vehicle is used to determine the reliability and validity of the output.
The results show that the new integrity algorithm has the capability to support a various
types of location-based ITS services.Saudi Arabia Cultural Burea
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