scholarly journals Shadow Matching: A New GNSS Positioning Technique for Urban Canyons

2011 ◽  
Vol 64 (3) ◽  
pp. 417-430 ◽  
Author(s):  
Paul D. Groves
Keyword(s):  
Urban Areas ◽  
Tall Buildings ◽  
Global Navigation Satellite Systems ◽  
Positioning System ◽  
Positioning Accuracy ◽  
Satellite Systems ◽  
Building Models ◽  
Satellite Visibility ◽  
Global Navigation Satellite ◽  
Cross Track

The Global Positioning System (GPS) is unreliable in dense urban areas, known as urban canyons, which have tall buildings or narrow streets. This is because the buildings block the signals from many of the satellites. Combining GPS with other Global Navigation Satellite Systems (GNSS) significantly increases the availability of direct line-of-sight signals. Modelling is used to demonstrate that, although this will enable accurate positioning along the direction of the street, the positioning accuracy in the cross-street direction will be poor because the unobstructed satellite signals travel along the street, rather than across it. A novel solution to this problem is to use 3D building models to improve cross-track positioning accuracy in urban canyons by predicting which satellites are visible from different locations and comparing this with the measured satellite visibility to determine position. Modelling is used to show that this shadow matching technique has the potential to achieve metre-order cross-street positioning in urban canyons. The issues to be addressed in developing a robust and practical shadow matching positioning system are then discussed and solutions proposed.

scholarly journals Filtering Link Outliers in Vehicle Trajectories by Spatial Reasoning

2021 ◽  
Vol 10 (5) ◽  
pp. 333
Author(s):  
Junli Liu ◽  
Miaomiao Pan ◽  
Xianfeng Song ◽  
Jing Wang ◽  
Kemin Zhu ◽  
...  
Keyword(s):  
Urban Areas ◽  
Spatial Reasoning ◽  
Sampling Interval ◽  
Global Navigation Satellite Systems ◽  
Quality Analysis ◽  
Ancillary Data ◽  
Satellite Systems ◽  
Positioning Errors ◽  
Vehicle Trajectories ◽  
Global Navigation Satellite

Vehicle trajectories derived from Global Navigation Satellite Systems (GNSS) are used in various traffic applications based on trajectory quality analysis for the development of successful traffic models. A trajectory consists of points and links that are connected, where both the points and links are subject to positioning errors in the GNSS. Existing trajectory filters focus on point outliers, but neglect link outliers on tracks caused by a long sampling interval. In this study, four categories of link outliers are defined, i.e., radial, drift, clustered, and shortcut; current available algorithms are applied to filter apparent point outliers for the first three categories, and a novel filtering approach is proposed for link outliers of the fourth category in urban areas using spatial reasoning rules without ancillary data. The proposed approach first measures specific geometric properties of links from trajectory databases and then evaluates the similarities of geometric measures among the links, following a set of spatial reasoning rules to determine link outliers. We tested this approach using taxi trajectory datasets for Beijing with a built-in sampling interval of 50 to 65 s. The results show that clustered links (27.14%) account for the majority of link outliers, followed by shortcut (6.53%), radial (3.91%), and drift (0.62%) outliers.

Past, present, and future of the technological tracking methods to assess tactical variables in team sports: A systematic review

2020 ◽  
Vol 234 (4) ◽  
pp. 281-290 ◽  
Author(s):  
Markel Rico-González ◽  
José Pino-Ortega ◽  
Fabio Y Nakamura ◽  
Felipe Arruda Moura ◽  
Daniel Rojas-Valverde ◽  
...  
Keyword(s):  
Global Positioning System ◽  
Systematic Reviews ◽  
Team Sports ◽  
Global Navigation Satellite Systems ◽  
Positioning System ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Global Positioning ◽  
Global Navigation ◽  
Global Navigation Satellite

The main aim of this work was to review the use of technological tracking methods to assess collective spatial-positioning variables in team sports. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and PICO design for systematic reviews, study identification was performed in four databases (PubMed, SPORTDiscus, ProQuest Central, and Web of Science). Articles were selected if they focused on player position and technological tracking methods. After duplicate removal, 2194 articles were identified based on the established search criteria, of which 72 articles were selected and analysed. Semi-automatic optic-based systems, Global Positioning System/Global Navigation Satellite Systems, and local positioning systems were used in 60%, 33% and 7% of the studies, respectively. All studies that measured tactical variables by local positioning system technology in team sports used local position measurement technology. Optic-based systems were used more often in the early years to analyse collective tactical behaviour during competition. Later, Global Positioning System/Global Navigation Satellite Systems became more frequent to measure behaviour in team sports during the training process. The possibility of using the same system during competition and training will facilitate the assessment of collective tactical behaviour in team sports.

scholarly journals Integrity and Collaboration in Dynamic Sensor Networks

Sensors ◽  
2018 ◽  
Vol 18 (7) ◽  
pp. 2400 ◽  
Author(s):  
Steffen Schön ◽  
Claus Brenner ◽  
Hamza Alkhatib ◽  
Max Coenen ◽  
Hani Dbouk ◽  
...  
Keyword(s):  
Sensor Networks ◽  
Urban Areas ◽  
Research Training ◽  
Training Group ◽  
Autonomous Driving ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Global Navigation Satellite ◽  
Map Data ◽  
Dynamic Sensor Networks

Global Navigation Satellite Systems (GNSS) deliver absolute position and velocity, as well as time information (P, V, T). However, in urban areas, the GNSS navigation performance is restricted due to signal obstructions and multipath. This is especially true for applications dealing with highly automatic or even autonomous driving. Subsequently, multi-sensor platforms including laser scanners and cameras, as well as map data are used to enhance the navigation performance, namely in accuracy, integrity, continuity and availability. Although well-established procedures for integrity monitoring exist for aircraft navigation, for sensors and fusion algorithms used in automotive navigation, these concepts are still lacking. The research training group i.c.sens, integrity and collaboration in dynamic sensor networks, aims to fill this gap and to contribute to relevant topics. This includes the definition of alternative integrity concepts for space and time based on set theory and interval mathematics, establishing new types of maps that report on the trustworthiness of the represented information, as well as taking advantage of collaboration by improved filters incorporating person and object tracking. In this paper, we describe our approach and summarize the preliminary results.

scholarly journals Galileo: a consolidação do sistema de posicionamento europeu

2020 ◽  
Vol 8 (4) ◽  
pp. 238
Author(s):  
Crislaine Menezes da Silva ◽  
Paulo De Tarso Setti Júnior ◽  
Daniele Barroca Marra Alves ◽  
João Francisco Galera Monico
Keyword(s):  
Global Positioning System ◽  
Global Navigation Satellite Systems ◽  
Positioning System ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Global Positioning ◽  
Global Navigation ◽  
Global Navigation Satellite

O Galileo é a contribuição da União Europeia ao GNSS (ingl. Global Navigation Satellite Systems – Sistemas de Navegação Global por Satélite) e está próximo da declaração da fase operacional completa, que deve ocorrer no final de 2020 ou início de 2021. Este sistema começou a ser concebido na década de 90, após a decisão do governo americano em não permitir que outras nações participassem da construção e manutenção do sistema NAVSTAR – GPS (ingl. Global Positioning System – Sistema de Posicionamento Global). O sistema Galileo é a primeira contribuição civil para o GNSS e foi desenvolvido de forma a ser independente dos outros sistemas nos segmentos espacial, de controle e operacional. Além disso, está sendo desenvolvido para ser interoperável e compatível com os outros GNSS, em especial o GPS. Nos últimos anos, o desenvolvimento do Galileo fez progressos significativos. A constelação atual compreende um total de 26 satélites orbitando a Terra, 22 operacionais, dos quais três pertencentes à primeira geração de satélites de validação de órbita, e a infraestrutura de controle terrestre está em pleno funcionamento.  Para o usuário, são transmitidos sinais em três frequências E1, E5 e E6. Os sinais em E1 e E5 são transmitidos nas mesmas frequências que os sinais GPS L1 e L5 e ambos sistemas usam princípios de modulação equivalentes. Isso é benéfico pois proporciona uma melhor cobertura e maior robustez para usuários que podem utilizar os sistemas de forma combinada. Além disso, o Galileo oferece vários novos serviços específicos, como o serviço aberto, o serviço de alta acurácia e de busca e resgate. Como o sistema Galileo está atualmente em fase final de implantação, faz-se necessário na literatura brasileira, um artigo que trate exclusivamente desse sistema, este artigo apresenta o estado da arte do sistema Galileo (julho de 2020). Resultados iniciais demonstraram que o Galileo tem acurácia comparável ao GPS, no posicionamento por ponto simples.

scholarly journals Satellite Availability and Service Performance Evaluation for Next-Generation GNSS, RNSS and LEO Augmentation Constellation

2021 ◽  
Vol 13 (18) ◽  
pp. 3698
Author(s):  
Haomeng Cui ◽  
Shoujian Zhang
Keyword(s):  
Satellite System ◽  
Low Earth Orbit ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Next Generation ◽  
Satellite Systems ◽  
Satellite Visibility ◽  
Under Construction ◽  
Global Navigation Satellite ◽  
Average Position

Positioning accuracy is affected by the combined effect of user range errors and the geometric distribution of satellites. Dilution of precision (DOP) is defined as the geometric strength of visible satellites. DOP is calculated based on the satellite broadcast or precise ephemerides. However, because the modernization program of next-generation navigation satellite systems is still under construction, there is a lack of real ephemerides to assess the performance of next-generation constellations. Without requiring real ephemerides, we describe a method to estimate satellite visibility and DOP. The improvement of four next-generation Global Navigation Satellite Systems (four-GNSS-NG), compared to the navigation constellations that are currently in operation (four-GNSS), is statistically analyzed. The augmentation of the full constellation the Quasi-Zenith Satellite System (7-QZSS) and the Navigation with Indian Constellation (11-NavIC) for regional users and the low Earth orbit (LEO) constellation enhancing four-GNSS performance are also analyzed based on this method. The results indicate that the average number visible satellites of the four-GNSS-NG will reach 44.86, and the average geometry DOP (GDOP) will be 1.19, which is an improvement of 17.3% and 7.8%, respectively. With the augmentation of the 120-satellite mixed-orbit LEO constellation, the multi-GNSS visible satellites will increase by 5 to 8 at all latitudes, while the GDOP will be reduced by 6.2% on average. Adding 7-QZSS and 11-NavIC to the four-GNSS-NG, 37.51 to 71.58 satellites are available on global scales. The average position DOP (PDOP), horizontal DOP (HDOP), vertical DOP (VDOP), and time DOP (TDOP) are reduced to 0.82, 0.46, 0.67 and 0.44, respectively.

Precise Point Positioning using Multi-Constellation GNSS Observations for Kinematic Applications

2015 ◽  
Vol 9 (1) ◽  
Author(s):  
Mahmoud Abd Rabbou ◽  
Ahmed El-Rabbany
Keyword(s):  
Urban Areas ◽  
Precise Point Positioning ◽  
Global Navigation Satellite Systems ◽  
Test Scenario ◽  
Satellite Systems ◽  
Satellite Geometry ◽  
Point Positioning ◽  
Kinematic Ppp ◽  
Gnss Measurements ◽  
Global Navigation Satellite

AbstractTraditional precise point positioning (PPP) is commonly based on un-differenced ionosphere-free linear combination of Global Positioning System (GPS) observations. Unfortunately, for kinematic applications, GPS often experiences poor satellite visibility or weak satellite geometry in urban areas. To overcome this limitation, we developed a PPP model, which combines the observations of three global navigation satellite systems (GNSS), namely GPS, GLONASS and Galileo. Both un-differenced and between-satellite single-difference (BSSD) ionosphere-free linear combinations of pseudorange and carrier phase GNSS measurements are processed. The performance of the combined GNSS PPP solution is compared with the GPS-only PPP solution using a real test scenario in downtown Kingston, Ontario. Inter-system biases between GPS and the other two systems are also studied and obtained as a byproduct of the PPP solution. It is shown that the addition of GLONASS observations improves the kinematic PPP solution accuracy in comparison with that of GPS-only solution. However, the contribution of adding Galileo observations is not significant due to the limited number of Galileo satellites launched up to date. In addition, BSSD solution is found to be superior to that of traditional un-differenced model.

scholarly journals FULLY AUTOMATIC FEATURE-BASED REGISTRATION OF MOBILE MAPPING AND AERIAL NADIR IMAGES FOR ENABLING THE ADJUSTMENT OF MOBILE PLATFORM LOCATIONS IN GNSS-DENIED URBAN ENVIRONMENTS

2017 ◽  
Vol XLII-1/W1 ◽  
pp. 317-323 ◽  
Author(s):  
P. Jende ◽  
F. Nex ◽  
M. Gerke ◽  
G. Vosselman
Keyword(s):  
Urban Areas ◽  
Urban Environments ◽  
Global Navigation Satellite Systems ◽  
Aerial Images ◽  
Mobile Mapping ◽  
High Resolution Data ◽  
Satellite Systems ◽  
Correct Orientation ◽  
Fully Automatic ◽  
Global Navigation Satellite

Mobile Mapping (MM) has gained significant importance in the realm of high-resolution data acquisition techniques. MM is able to record georeferenced street-level data in a continuous (laser scanners) and/or discrete (cameras) fashion. MM’s georeferencing relies on a conjunction of Global Navigation Satellite Systems (GNSS), Inertial Measurement Units (IMU) and optionally on odometry sensors. While this technique does not pose a problem for absolute positioning in open areas, its reliability and accuracy may be diminished in urban areas where high-rise buildings and other tall objects can obstruct the direct line-of-sight between the satellite and the receiver unit. Consequently, multipath measurements or complete signal outages impede the MM platform’s localisation and may affect the accurate georeferencing of collected data. This paper presents a technique to recover correct orientation parameters for MM imaging platforms by utilising aerial images as an external georeferencing source. This is achieved by a fully automatic registration strategy which takes into account the overall differences between aerial and MM data, such as scale, illumination, perspective and content. Based on these correspondences, MM data can be verified and/or corrected by using an adjustment solution. The registration strategy is discussed and results in a success rate of about 95 %.

Vulnerability Assessment of the U.S. Transportation Infrastructure that Relies on the Global Positioning System

2003 ◽  
Vol 56 (2) ◽  
pp. 185-193 ◽  
Author(s):  
James V. Carroll
Keyword(s):  
Global Positioning System ◽  
The United States ◽  
Global Navigation Satellite Systems ◽  
Positioning System ◽  
Satellite Systems ◽  
The Public ◽  
Transportation Modes ◽  
Global Positioning ◽  
Global Navigation Satellite ◽  
The U.S

During the course of its development for military use and more recent extension to many civilian uses, vulnerabilities of Global Navigation Satellite Systems (GNSS) – in the United States the Global Positioning System (GPS) – have become apparent. The vulnerabilities arise from natural, intentional, and unintentional sources. Increasing civilian and military reliance on GNSS brings with it a vital need to identify the critical vulnerabilities to civilian users, and to develop a plan to mitigate these vulnerabilities. This paper summarizes the findings of the U.S. Department of Transportation (DOT) vulnerability study that addresses these issues. The key findings are that satellite navigation users are vulnerable to several classes of disruption that affect all transportation modes and related infrastructure; but also that the vulnerabilities can be mitigated by awareness, planning, and using independent backup systems and/or alternate procedures in safety-critical applications. To gain the full benefits of GNSS, it will be necessary to analyse safety-of-life vulnerabilities in detail, and to determine the means and costs of reducing these risks to acceptable levels. The complete assessment report, of which this paper is a synopsis, was released to the public on September 10, 2001. Although the basic findings apply to all GNSS, the assessment focused on the GPS, in response to the enabling Presidential Decision Directive.

scholarly journals Intelligent Urban Positioning: Integration of Shadow Matching with 3D-Mapping-Aided GNSS Ranging

2017 ◽  
Vol 71 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Mounir Adjrad ◽  
Paul D. Groves
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Covariance Matrices ◽  
Global Navigation Satellite Systems ◽  
3D Mapping ◽  
Deterministic Approach ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Error Covariance ◽  
Global Navigation Satellite

In dense urban areas, conventional Global Navigation Satellite Systems (GNSS) positioning can exhibit errors of tens of metres due to the obstruction and reflection of the signals by the surrounding buildings. By using Three-Dimensional (3D) mapping of the buildings, the accuracy can be significantly improved. This paper demonstrates the first integration of GNSS shadow matching with 3D-mapping-aided GNSS ranging. The integration is performed in the position domain, whereby separate ranging and shadow matching position solutions are computed, then combined using direction-dependent weighting. Two weighting strategies are compared, one based on the computation of ranging-based and shadow matching position error covariance matrices, and a deterministic approach based on the street azimuth. Using experimental data collected from a u-blox GNSS receiver, it is shown that both integrated position solutions are significantly more accurate than either shadow matching or 3D-mapping-aided ranging on their own. The overall Root Mean Square (RMS) horizontal accuracy obtained using covariance-based weighting was 6·1 m, a factor of four improvement on the 25·9 m obtained using conventional GNSS positioning. Results are also presented using smartphone data, where shadow matching is integrated with conventional GNSS positioning.

scholarly journals Integrity Analysis for GPS-Based Navigation of UAVs in Urban Environment

Robotics ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 66
Author(s):  
Oguz Kagan Isik ◽  
Juhyeon Hong ◽  
Ivan Petrunin ◽  
Antonios Tsourdos
Keyword(s):  
Urban Environment ◽  
Urban Areas ◽  
Environmental Parameters ◽  
Urban Environments ◽  
Rate Of Change ◽  
Global Navigation Satellite Systems ◽  
Integrity Monitoring ◽  
Satellite Systems ◽  
Joint Consideration ◽  
Global Navigation Satellite

The increasing use of Unmanned Aerial Vehicles (UAVs) in safety-critical missions in both civilian and military areas demands accurate and reliable navigation, where one of the key sources of navigation information is presented by Global Navigation Satellite Systems (GNSS). In challenging conditions, for example, in urban areas, the accuracy of GNSS-based navigation may degrade significantly due to user-satellite geometry and obscuration issues without being noticed by the user. Therefore, considering the essentially dynamic rate of change in this type of environment, integrity monitoring is of critical importance for understanding the level of trust we have in positioning and timing data. In this paper, the dilution of precision (DOP) coefficients under nominal and challenging conditions were investigated for the purpose of integrity monitoring in urban environments. By analyzing positioning information in a simulated urban environment using a software-based GNSS receiver, the integrity monitoring approach based on joint consideration of GNSS observables and environmental parameters has been proposed. It was shown that DOP coefficients, when considered together with a number of visible satellites and cut-off elevations specific to the urban environment carry valuable integrity information that is difficult to get using existing integrity monitoring approaches. This has allowed generating indirect integrity measures based on cut-off elevation and satellite visibility that can be used for UAV path planning and guidance in urban environments.

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