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Etude du traitement de données gravimétriques acquises lors de levés aériens / M. Abbasi (2006)
Titre : Etude du traitement de données gravimétriques acquises lors de levés aériens Type de document : Thèse/HDR Auteurs : M. Abbasi, Auteur ; Jean-Pierre Barriot, Directeur de thèse Editeur : Toulouse : Université de Toulouse 3 Paul Sabatier Année de publication : 2006 Importance : 198 p. Format : 21 x 30 cm Note générale : Bibliographie
Thèse pour obtenir le grade de docteur de l'Université de Toulouse 3, GéodésieLangues : Français (fre) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] accélération de la pesanteur
[Termes IGN] Alpes occidentales
[Termes IGN] filtrage du bruit
[Termes IGN] GPS-INS
[Termes IGN] gravimètre supraconducteur
[Termes IGN] gravimétrie aérienne
[Termes IGN] levé gravimétrique
[Termes IGN] méthode des moindres carrés
[Termes IGN] traitement de données
[Termes IGN] vitesseIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) [introduction] [...] Le document est organisé en 3 parties : 1. Instrumentations et systèmes de mesure en gravimétrie aéroportée, 2. Modélisation mathématique, 3. Application dos modèles sur les données. Le Chapitre 1 constitue la présente introduction. Le Chapitre 2 couvre la première partie de la thèse. Il est constitué de 3 sections : les systèmes de mesure GPS, INS et gravimètre. Chaque section explique en bref les éléments de base du système de mesure correspondant. Nous avons d'abord travaillé sur la modélisation mathématique du gravimètre LaCoste & Romberg en dérivant les équations de la dynamique Newtonienne présentées dans un système de coordonnées lié au gravimètre. Le Chapitre 3 décrit cette modélisation, sous la forme d'une équation différentielle. Ensuite au Chapitre 4, à partir de ce modèle mathématique, nous avons développé une nouvelle méthode de filtrage dans le domaine spatial, méthode basée sur la transformation de l'équation différentielle du gravimètre en une équation intégrale. Pour résoudre cette équation, nous avons utilisé la méthode de régularisation en théorie des moindres carrés. Une partie du Chapitre 4 présente le détail des calculs numériques des paramètres nécessaires pour mise en œuvre de notre nouvelle méthode de filtrage. Les données utilisées sont issues du levé Alpin, levé dont le déroulement est rappelé au Chapitre 5. Nous avons enfin appliqué notre méthode de filtrage spatial sur ces données. Une comparaison avec les résultats du filtrage classique est effectuée à la fin de la thèse (Chapitre 6). Note de contenu : 1 Introduction
1.1 La gravimétrie aéroportée
1.2 Les différents systèmes d'acquisition en gravimétrie aéroportée
1.3 Définition du problème
1.4 Organisation du manuscrit
2 Instrumentation et systèmes de mesure en gravimétrie aéroportée
2.1 Le système GPS utilisé en gravimétrie aéroportée
2.1.1 Mesures GPS
2.1.2 Observables différenciées
2.1.3 Combinaison linéaire de mesures
2.1.4 Traitement des données
2.2 Le Système de Navigation Inertielle (INS)
2.2.1 Les types d'accéléromètres
2.2.2 Les type de gyroscopes
2.2.3 Les types d'INS
2.3 Le gravimètre stabilisé de LaCoste & Romberg
2.3.1 Capteur du gravimètre LaCoste & Romberg
2.3.2 La Plate-forme stabilisée
2.3.3 Correction sur la gravité mesurée due à l'imperfection du nivellement
3 Modèle mathématique du fonctionnement du gravimètre
3.1 Référentiels utilisés en gravimétrie mobile
3.2 Vitesse et accélération dans le repère de mesure
3.2.1 Relation pour les vitesses
3.2.2 Relation pour les accélérations
3.3 Equation du capteur gravimétrique LaCoste & Romberg
3.3.1 Application de la deuxième loi de Newton
3.3.2 Equation différentielle du mouvement du fléau
3.3.3 Equation simplifiée du mouvement du fléau
3.3.4 Accélérations parasites dues aux mouvements de l'avion
4 Modélisation de la gravité à partir de mesures aérogravimétriques
4.1 Pré-traitement des données aérogravimétriques
4.1.1 Vérification pour clés lacunes et clés erreurs grossières
4.1.2 Synchronisation des mesures
4.1.3 Analyse spectrale
4.2 Filtrage direct des données aérogravimétriques
4.3 Notre nouvelle approche : l'équation intégrale du gravimètre
4.3.1 De l'équation différentielle à l'équation intégrale
4.3.2 Résoudre l'équation intégrale du gravimètre
4.4 Matrices nécessaires à la solution au sens des moindres carrés
4.4.1 Matrice de covariance a priori des inconnues
4.4.2 Vecteur d'entrée de l'équation intégrale et matrice de covariance associée
4.5 Ajustement des valeurs de la gravité aux points de croisement
5 Le levé aérogravimétrique sur les Alpes Occidentales
5.1 Situation géographique du levé
5.2 L'avion
5.3 Trajectographie de l'avion
5.3.1 Positionnement de l'avion par GPS
5.3.2 La centrale inertielle de navigation
6 Résultats numériques et validations associées
6.1 Pré-traitement
6.1.1 Histogrammes des paramètres
6.1.2 Elimination des lignes de vol incohérentes
6.2 Perturbations de gravité calculées par utilisation de l'équation simplifiée du gravimètre
6.3 Perturbation de gravité calculée avec l'équation différentielle complète du gravimètre
6.4 Perturbation de gravité selon l'équation intégrale du gravimètre
6.4.1 Résultats d'application des équations de contrainte aux points de croisement
6.5 Validation clés cartes clé la perturbation de gravité calculée à l'altitude de vol
7 Conclusion et perspectives
A Vitesse et accélération dans le cas de changement de repère
B Développement des termes de l'Equation (3.13) : le gravimètre dans 1 repère de Copernic
C Expressions de l'accélération verticale et l'accélération Eötvös exercée sur l'avion
D La méthode d'Helmert pour l'estimation des facteurs de variance
E La différentiation de séries chronologiques et l'estimation des matrices de covariance associées
F Equations des contraintes aux points de croisementsNuméro de notice : 14036 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de doctorat : Géodésie : Toulouse 3 : 2006 Organisme de stage : Laboratoire de Dynamique Terrestre et Planétaire nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45236 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 14036-01 THESE Livre Centre de documentation Thèses Disponible Improving the precision and accuracy of geodetic GPS / A. Bilich (2006)
Titre : Improving the precision and accuracy of geodetic GPS : applications to multipath and seismology Type de document : Thèse/HDR Auteurs : A. Bilich, Auteur ; K. Larson, Directeur de thèse Editeur : Boulder [Etats-Unis] : University of Colorado Année de publication : 2006 Importance : 374 p. Format : 21 x 28 cm ISBN/ISSN/EAN : 978-0-542-94205-1 Note générale : Bibliographie
A thesis submitted to the Faculty of the graduate school of the University of Colorado in partial fulfillment of the requirements for the degree of Doctor of philosophy, department of aerospace engineering sciencesLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] égalisation
[Termes IGN] erreur de positionnement
[Termes IGN] filtrage du bruit
[Termes IGN] mesurage de phase
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] positionnement par GPS
[Termes IGN] rapport signal sur bruit
[Termes IGN] réduction
[Termes IGN] séisme
[Termes IGN] sismologie
[Termes IGN] trajet multipleIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) The Global Positioning System (GPS) enables precise and accurate determination of position anywhere on anywhere on the Earth, a boon to the field of geodesy. Although great advances in geodetic GPS positioning precision and accuracy have been made over the last decade, improvements can still be made. This dissertation addresses GPS positioning error from two different directions---understanding and taking advantage of the repeating nature of some errors, or understanding and taking advantage of the relationship between errors in different contemporaneous GPS observables. In the area of high-rate GPS positioning, repeating errors have a substantial impact on the solution. In this dissertation, I study high-rate GPS error reduction using data from the 2002 Denali Fault earthquake. I apply the techniques of modified sidereal filtering and spatial filtering to positions from 25 GPS stations throughout northwestern North America, and I develop improvements to these methods such as data equalization and careful selection of sidereal filtering sites. Substantial reduction in noise magnitude is achieved through proper application of sidereal and spatial filters, and the resulting 'GPS seismograms' show excellent agreement to records from seismometers. Multipath, where GPS signals arrive by more than one path and thereby create a range error, can be understood through the GPS observables. Multipath effects on GPS carrier phase, pseudorange, and signal-to-noise ratio (SNR) measurements are different but linked by the same underlying principles. In this dissertation, I explain multipath effects on the GPS observables and define multipath in terms of conditions specific to geodetic GPS installations and receivers. I develop two approaches to multipath errors, both using SNR measurements---a graphical method for multipath assessment, and a computational method for multipath modeling and carrier phase error reduction. The graphical method shows great promise for understanding spatial and temporal variability in multipath errors, but provides no avenue for removing these errors. The theory behind SNR modeling is robust, but complicated to implement with geodetic GPS measurements of SNR. I discuss the difficulties inherent in SNR modeling and demonstrate how this technique is of limited utility for geodetic GPS even in the most simple of multipath environments. Note de contenu : 1 Introduction
1.1 Global Positioning System Background
1.2 GPS Observables
1.3 Position Estimation with GIPSY
1.3.1 Satellite Orbits
1.3.2 Earth and Observation Models
1.3.3 Removing Ionospheric Effects
1.3.4 Unmodeled Terms
1.3.5 Position Solution
2 Overview of High-Rate Positioning Research
2.1 Comparision of GPS and Seismologic Measurements
2.2 Previous Work in GPS Seismology
2.3 Case Study: 2002 November 3 Denali Fault Event
2.3.1 Denali Fault earthquake
2.3.2 GPS network and analysis
2.3.3 Error-reduction methodology
3 High-rate GPS Techniques
3.1 Sidereal Filtering
3.1.1 Orbital repeat period
3.1.2 Modified sidereal filtering (MSF) method
3.1.3 Variables in sidereal filtering process
3.2 Additional Data Analysis
3.2.1 Ambiguity resolution
3.2.2 Data editing
3.3 Spatial Filtering
3.3.1 Common-mode errors
3.3.2 Spatial filtering method
3.3.3 Spatial filtering sites
3.3.4 Role of the reference site and filter order
4 High-rate GPS Results and Discussion
4.1 Surface Waves Recorded by GPS
4.2 Positioning Noise
4.2.1 Noise floor of GPS receivers
4.2.2 Generalized noise in GPS positions
4.3 Comparison to Seismic Recordings
4.4 Summary and Conclusions
4.5 Future Work
5 Overview of Multipath Research
5.1 Previous Work
5.2 Research Motivation and Overview
6 Principles of Multipath and SNR
6.1 GPS Receiver Signal Tracking
6.2 Multipath Terminology
6.3 Multipath Effects on GPS Observables
6.3.1 Pseudorange multipath
6.3.2 Carrier phase multipath
6.3.3 Effect of multipath on SNR
6.4 Summary of Multipath Theory
7 Multipath Under Geodetic GPS Conditions
7.1 Multipath Geometry for the Geodetic Case
7.1.1 Multipath geometry and errors
7.1.2 Time-varying behavior of ø and SNR
7.1.3 Multipath geometry and periodicity
7.1.4 Resolvable multipath frequencies
7.1.5 Multipath phasor spin
7.1.6 Direct and multipath amplitudes
7.1.7 Summary
7.2 Geodetic GPS Receivers
7.2.1 Computation and reporting of SNR
7.2.2 Characteristics of geodetic GPS SNR
7.2.3 Correlation of SNR and pseudorange multipath
7.2.4 Conclusions
8 Multipath Assessment for Permanent GPS Stations
8.1 SNR Power Spectral Maps
8.1.1 Spectral power estimates
8.1.2 Representation of gridded spectral power
8.2 Examples of Power Spectral Maps
8.2.1 TASH: tall pillar
8.2.2 MKEA: reflections from angled surfaces
8.2.3 CHUR: variable topography
8.3 Discussion and Future Work
9 Estimation of SNR-based Multipath Corrections
9.1 Direct Signal Amplitude and SNR Due to Multipath
9.2 Signal Conditioning
9.3 Multipath Frequency Estimation Via Sliding-Window Fast Fourier Transform (SWFFT)
9.4 Amplitude and Multipath Phase Estimation Via Adaptive Least Squares (ALS)
9.5 Construction of SNR and Multipath Corrections
9.6 Simulations
10 Phase Multipath Mitigation for GPS Stations
10.1 Salar de Uyuni Experiment
10.1.1 Phase errors
10.1.2 Phase multipath corrections
10.1.3 Effect of corrections on residuals and positions
10.2 TASH/KIT3 Network
10.2.1 SNR data
10.2.2 Phase multipath corrections
10.2.3 Phase errors and corrections
10.3 Discussion and Future Work
11 ConclusionsNuméro de notice : 14325 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse française Note de thèse : Thèse de doctorat : philosophy. department of aerospace engineering sciences : Boulder,University of Colorado : 2006 nature-HAL : Thèse DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=45244 Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 14325-01 THESE Livre Centre de documentation Thèses Disponible
Titre : Precise relative positioning of formation flying spacecraft using GPS Type de document : Thèse/HDR Auteurs : Remco Kroes, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2006 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 61 Importance : 163 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-296-2 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] ambiguïté entière
[Termes IGN] compensation Lambda
[Termes IGN] erreur systématique
[Termes IGN] filtre de Kalman
[Termes IGN] GPS-INS
[Termes IGN] GRACE
[Termes IGN] image TerraSAR-X
[Termes IGN] mesurage de pseudo-distance
[Termes IGN] méthode des moindres carrés
[Termes IGN] navigation spatiale
[Termes IGN] orbitographie par GNSS
[Termes IGN] positionnement différentiel
[Termes IGN] positionnement par GPS
[Termes IGN] précision millimétrique
[Termes IGN] qualité des données
[Termes IGN] résolution d'ambiguïté
[Termes IGN] signal GPSIndex. décimale : 30.70 Navigation et positionnement Résumé : (Auteur) Spacecraft formation flying is currently considered as a key technology for advanced space missions. Compared to large individual spacecraft, the distribution of Sensor systems amongst multiple platforms offers improved flexibility and redundancy, shorter times to mission and the prospect of being more cost effective. Besides these advantages, satellite formations in low Earth orbit provide advanced science opportunities that cannot, or not easily, be realized with single spacecraft. One of the fundamental issues of spacecraft formation flying is the determination of the relative state (position and velocity) between the satellite vehicles within the formation. Knowledge of these relative states in (near) real-time is important for operational aspects. In addition, some of the scientific applications, such as high resolution interferometry, require an accurate post-facto knowledge of these States. The goal of this dissertation is therefore to develop, implement and test a method for high precise post-facto relative positioning of formation flying spacecraft, using GPS observation data. The need for such a methodology comes from scientific satellite formation flying missions that are currently being planned. A good example here is the Synthetic Aperture Radar (SAR) interferometry formation consisting of the TerraSAR-X and TanDEM-X satellites. The primary mission objective here requires the relative position to be known within a 2 mm precision (1-dimensional).
GPS receivers are often considered as the primary instruments for precise relative navigation in future satellite formation flying missions. As is commonly known, precise relative positioning between GPS receivers in geodetic networks is exercised on a routine basis. Furthermore, GPS receivers are already frequently used onboard satellites to perform all kinds of navigational tasks, are suitable for real-time applications and provide measurements with a 3-dimensional nature.
Previous studies carried out in this research area focussed on the real-time or operational aspects, and all used GPS data obtained from software or hardware-in-the-loop simulations. This dissertation clearly distinguishes itself due to the fact that the developed methodology has been tested using real-world GPS data from the GRACE mission, which in addition also provides a precise way to validate the obtained results by means of the GRACE K/Ka-Band Ranging System (KBR) observations.
One of the key aspects of any GPS positioning application is the quality of the observation data used. To this extent an in-flight performance analysis of the used GRACE (and CHAMP) GPS data bas been carried out. The results show that the GRACE GPS pseudorange observations, on the individual frequencies, are subject to systematic errors in the order of 10-15 cm. Furthermore, an assessment of the noise of both the GPS pseudorange and carrier phase data demonstrates that the noise of the GRACE B observation data is significantly lower.
When using GPS for precise relative spacecraft positioning, the trajectory or orbit of one of the spacecraft, serving as the reference, has to be known to the best possible extent. In order to facilitate this, a total of three precise orbit determination strategies, using undifferenced ionosphere free GPS pseudorange and carrier phase observations, have been implemented and tested. They comprise a kinematic and reduced dynamic batch LSQ estimation method, as well as an extended Kalman filter/smoother (EKF), that also form the conceptual basis for the relative spacecraft positioning strategies. Each of the precise orbit determination concepts has been tested using GPS data from the CHAMP and GRACE missions. The reduced dynamic batch LSQ orbits were validated with Satellite Laser Ranging data, where the residuals showed an RMS of 3-4 cm.
Out of a total of four possible processing strategies that have been identified for relative spacecraft positioning, only an extended Kalman filter/smoother has proven to work satisfactorily when tested on the real-world GRACE GPS data. The EKF processes single difference GPS pseudorange and carrier phase observations and uses (pseudo) relative spacecraft dynamics to propagate the relative satellite state over the observation epochs. Despite its single difference parametrization the EKF can still resolve and incorporate the integer double difference carrier phase ambiguities, which is commonly regarded as, and has proven to be in this dissertation, the key to precise GPS based relative positioning. Estimation of the integer ambiguities is accomplished by the well known Least Squares Ambiguity Decorrelation Adjustment (LAMBDA) method. Due to the presence of systematic errors in the GRACE GPS data, a relatively conservative validation of the estimated integer ambiguity parameters was found to be required prior to their incorporation in the filter. When validating the daily ambiguity fixed GRACE relative position solutions from the EKF with the KBR observations, it has been shown that an actual overall relative position precision of 0.9 mm (1-dimensional) over a 101 day data arc is achieved. This dissertation is the first that proves that such precision can be truly obtained for real-world relative spacecraft positioning applications.Note de contenu : 1 Introduction
1.1 Spacecraft formation flying using GPS
1.2 Research objective and motivation
1.3 The CHAMP and GRACE satellite missions
1.4 Outline
2 GPS observations
2.1 Observation types
2.3 Linear data combinations
2.4 Linearization for positioning
2.5 Relative positioning models
2.6 GPS data quality
3 Precise orbit determination
3.1 GPS orbit and clock products
3.2 Reference frame transformations.
3.3 Kinematic orbit determination.
3.4 Reduced dynamic orbit determination
3.5 GHOST toolkit
3.6 POD results
4 Relative spacecraft positioning
4.1 Integer ambiguity resolution
4.2 Proposed processing strategies
4.3 Details of the extended Kalman filter
4.4 Extended Kalman filter results.
4.5 Some words on
5 Conclusions and outlookNuméro de notice : 15179 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : sans En ligne : https://www.ncgeo.nl/downloads/61Kroes.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55089 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 15179-01 30.70 Livre Centre de documentation Géodésie Disponible 15179-02 30.70 Livre Centre de documentation Géodésie Disponible Reliability of direct georeferencing: An overview of the current approaches and possibilities / Jan Skaloud (2006)
Titre : Reliability of direct georeferencing: An overview of the current approaches and possibilities : Final report on phase 1 Type de document : Rapport Auteurs : Jan Skaloud, Auteur Editeur : Dublin : European Spatial Data Research EuroSDR Année de publication : 2006 Collection : EuroSDR official publication, ISSN 0257-0505 num. 51 Importance : pp 143 - 148 Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Photogrammétrie numérique
[Termes IGN] capteur spatial
[Termes IGN] centrale inertielle
[Termes IGN] contrôle qualité
[Termes IGN] données GNSS
[Termes IGN] étalonnage de capteur (imagerie)
[Termes IGN] filtre de Kalman
[Termes IGN] géoréférencement direct
[Termes IGN] GPS-INS
[Termes IGN] orientation du capteur intégrée
[Termes IGN] Receiver Autonomous Integrity MonitoringRésumé : (auteur) After some initial hesitations, the direct georeferencing (DG) of airborne sensors by GPS/INS is now a widely accepted approach in the airborne mapping industry. Implementing DG not only speeds up the mapping process and thus increases the productivity, but also opens the door to new monitoring applications. Although the system manufactures tend to claim that DG is a well established technique and no longer a research topic, the technology users often encounter pitfalls due to undetected sensor behavior, varying data quality and consistency. One could almost claim that the reliability of DG is the Achilles’ heel of this otherwise revolutionary approach in civil airborne mapping. EuroSDR has recognized this problem and would like to address it in several phases. First phase of this effort are some preliminary investigations, charting the current situation and making suggestions for further research. The investigations are divided into the following technology fields: GNSS, inertial sensors and estimation methods, integrity and communication, calibration and integrated sensor orientation. Each field describes the current situation with respect to DG and discusses additional existing possibilities. These do not claim to be complete or exhaustive; however, they claim to address the essential features, methods and processes, the combination of which could increase the reliability of DG substantially without setting large side penalties. Numéro de notice : H2006-002 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Chapître / contribution En ligne : http://www.eurosdr.net/publications/official-publication-no-51-2006 Format de la ressource électronique : URL bulletin Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=93668 Documents numériques
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Reliability of Direct Georeferencing... - pdf auteurAdobe Acrobat PDF
Titre : The Swiss trolley : a modular system for track surveying Type de document : Rapport Auteurs : Ralph Glaus, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2006 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 70 Importance : 184 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-13-0 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] capteur imageur
[Termes IGN] capteur non-imageur
[Termes IGN] données localisées
[Termes IGN] filtre de Kalman
[Termes IGN] fonction spline
[Termes IGN] fusion de données
[Termes IGN] GPS en mode cinématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] GPS-INS
[Termes IGN] lissage de données
[Termes IGN] navigation à l'estime
[Termes IGN] odomètre
[Termes IGN] positionnement absolu
[Termes IGN] précision millimétrique
[Termes IGN] prise de vue terrestre
[Termes IGN] réseau ferroviaire
[Termes IGN] surveillance d'ouvrage
[Termes IGN] tachéomètre électronique
[Termes IGN] transport ferroviaireIndex. décimale : 30.70 Navigation et positionnement Résumé : (Auteur) Modern railway infrastructure requires accurate, absolute referenced spatial data for project planning, construction and maintenance. On the one hand, passenger safety and travel comfort depend to a large extent on accurate tracks. On the other hand, absolute referenced coordinates of railway assets facilitate data exchange between railway operators and third parties. In addition, time slots for maintenance are short, due to the high volumes of traffic on major railway lines. Thus, flexible surveying systems are required yielding accurate data within a short time. The multi-sensor platform Swiss Trolley, which offers such a flexible system, copes with absolute referenced spatial data. The platform is mounted on a track vehicle. This allows for a complete description of the track environment in kinematic mode with a minimum of interference time with regular traffic.
The Swiss Trolley features a modular design. A basic module for assessing track key parameters such as chainage, cant, twist, gradients and track gauge covers monitoring tasks on construction sites. A positioning module integrating GPS or total stations allows for the determination of the track axis. A further scan module can be used to generate absolute referenced point clouds in the track environment.
This work compiles the development steps of the Swiss Trolley. Relevant side conditions re-garding track surveying, coming from track geometry and the railway operators are summarised and state-of-the-art systems are reviewed. Based on these premises, a niche for Swiss Trolley applications is defined. Sensors providing geometric data in the track environment are evaluated in regard to their suitability and error behaviour.
The key problem of the trolley positioning consists in determining the six degrees of freedom of the multi-sensor platform at any point in time. The chosen kinematic approach asks for a careful treatment of time constraints. Each data string coming from a specific sensor must own an accurate time tag. Kinematic surveys at walking speed with subcentimetric accuracy require time tags with millisecond accuracy.
The incorporated sensors were investigated regarding their error behaviour. Calibration issues are addressed and approaches for the bias determination are presented. Models for correcting collimation errors and nuisance accelearations are given for the pendulum inclination sensors used. Moreover, emphasis was placed on biases emerging at kinematic surveys for the particular optical total station used. Reduction models for the laser scanner data are proposed and calibration procedures providing intrinsic orientation and latency parameters are given.
A kinematic model for Swiss Trolley surveys based on the Frenet base system and its canonical representation was developed. Explicit formulae are given for runs on geometric elements dominating in the railway track environment. For the mutual data processing, a loosely coupled filter concept is proposed consisting of data pre-processing, synchronisation and filtering steps. The core of data processing is a Kalman filter, estimating vehicle and track states in an absolute or a relative reference frame. By means of the filter approach, the observations of the involved sensors can be integrated in a spatial model. Individual filter runs can be assembled by an additional merge step. Merged runs in up and down direction allow for a quality assessment and also allow for the monitoring of eventually remaining biases such as a boresight misalignment or inclination sensor zero point offsets.
Positioning accuracies for the static and kinematic case were assessed on the one hand by the comparison of up and down runs. On the other hand, comparisons were carried out with independently measured reference data. The static error behaviour of the Swiss Trolley could be evaluated by using a slab track alignment. Submillimetric positioning accuracies were obtained in combination with high-precision total stations. Kinematic positioning accuracy mainly depends on the positioning sensor used. Optical total stations providing synchronised angle and distance data allow for subcentimetric positioning. High-precision DGPS position-ing yields subcentimetric accuracy for the horizontal component. The typical vertical accuracy is better than two centimetres. The integrated longitudinally mounted inclination sensor slightly augments the mere GPS solution. The attitude determination of the platform is a result of the combined data treatment. For GPS surveys, the typical pitch angle accuracy is two mrad. Yaw angles essentially correspond to the derivation of the trajectory with respect to the covered path and are determined with one mrad accuracy. Roll angle accuracy is dominated by the inclination sensor measurements across the track. The typical accuracy is 0.3 mrad. For the scan module, laser dots in the absolute reference frame are degraded by the uncertainty of the trajectory and the platform attitude amplified by a geometry-depending lever. The absolute accuracy of such a dot is three centimetres using a time-of-flight laser scanner. Relative accuracy between two adjacent dots amounts to five millimetres.
The Swiss Trolley was successfully applied on numerous assignments. Adaptations for the multi-sensor platform exist for tunnel site locomotives and road-vehicles.Note de contenu : 1 Introduction
2 Track Geometry
2.1 Nominal Geometries
2.1.1 Introduction
2.1.2 Horizontal Layout
2.1.3 Vertical Layout
2.2 Rules and Standards of Different Countries
2.2.1 Horizontal Layout
2.2.2 Vertical Layout
2.2.3 Cant
2.3 Kinematic Model of Motion
2.3.1 Kinematics in the Frenet System
2.3.2 Canonical Representation of the Most Common Track Curves
2.4 Remarks on Track Accuracy
2.4.1 General Remarks
2.4.2 Relative and Absolute Accuracy of a Track
2.5 Methods for Track Surveying
2.5.1 Overview
2.5.2 Relative Track Surveying
2.5.3 Absolute Track Surveying
2.5.4 Selected Track-Surveying Systems
2.5.5 The Swiss Trolley - Finding the Niche
3 Potentials and Limitations of a Kinematic Track-Surveying System
3.1 Kinematic Surveying
3.2 Absolute Position Fixing
3.2.1 GNSS
3.2.2 Tracking Total Stations
3.3 Dead Reckoning
3.3.1 Inertial Navigation Systems (INS)
3.3.2 Yaw Rates by Chord Techniques
3.3.3 Odometers
3.3.4 Height Determination by an Inclination Sensor
3.4 Attitude Determination
3.5 Kinematic Surveys of the Railway Inventory
3.5.1 Track Gauge Measuring Systems
3.5.2 Laser Scanners
3.5.3 3D Cameras
3.5.4 Ground Penetration Radar (GPR)
3.6 Synchronisation
3.7 Modelling
3.8 Transformation
4 The Track-Surveying Trolley
4.1 Introduction
4.1.1 Development
4.1.2 Concept
4.2 Data Acquisition
4.2.1 Electronic Box
4.2.2 A/D Conversion
4.2.3 Data Synchronisation
4.3 Reconstruction
4.4 Inclination Sensors
4.4.1 Sensor Characteristics
4.4.2 Calibration of Characteristic Curve
4.4.3 Temperature Influences
4.4.4 Corrections for Non-Orthogonalities (Collimation Error)
4.4.5 Dynamic Behaviour of the Inclination Sensor
4.4.6 Transformation of the Inclination Angles into the Body-System
4.5 Track Gauge Measuring System
4.5.1 Characteristics and Measuring Principle of the Track Gauge Measuring System
4.5.2 Calibration
4.6 Odometers
4.6.1 Characteristics and Calibration
4.7 Integration of Tracking Total Stations
4.7.1 Characteristics
4.7.2 Common Total Station Biases
4.7.3 Deflections of the Vertical
4.7.4 Surveys in Canted Sections
4.7.5 Synchronisation of Distances and Angles
4.7.6 Internal Tacheometer and Radio Latencies
4.8 Integration of GPS
4.8.1 Characteristics
4.8.2 NMEA Data
4.9 Boresight Calibration of Prism and Antenna Phase Centre
4.10 Laser Scanners
4.10.1 Characteristics
4.10.2 Model
4.10.3 Yaw Angle Correction
4.10.4 Evaluation of the Laser Scanner Precision
4.10.5 Variance Propagation for a Given Scanner Arrangement
4.10.6 Kinematic Calibration of Rmb, xmb and the Latency
5 Data Processing
5.1 Introduction
5.2 Post-Processing Software Concept
5.3 Data Preprocessing
5.3.1 Blunder Labelling
5.3.2 Reduction, Model
5.3.3 Linear Filters
5.3.4 Synchronisation
5.3.5 Reduction to the Centre Line of the Track
5.4 Trajectory Smoothing by a Kalman Filter
5.4.1 Discrete Kalman Filter
5.4.2 Backward Filter and Smoother
5.4.3 Absolute Model
5.4.4 Relative Model
5.5 Smoothing Splines
5.5.1 Smoothing Splines with First Derivatives
5.5.2 Comparison between Kalman Filter and Smoothing Splines
5.6 Merging Trajectories
5.6.1 Strategies for Merging
5.6.2 Chaining the Pieces
5.6.3 Merging
5.6.4 Linking Scans to Merged Trajectories
6 Applications
6.1 Slab Track Alignment
6.2 Kinematic Track Axis Surveys
6.2.1 Comparison between Forward Filter, Backward Filter and Smoother
6.2.2 Filter Tuning
6.2.3 Comparison between Absolute and Relative Model
6.2.4 The Influence of Inclinometer Measurement on GPS Heights
6.2.5 The Smoother in Action - GPS Example
6.2.6 The Smoother in Action - Total Station Example
6.3 Kinematic Scanning
7 ConclusionsNuméro de notice : 15261 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Rapport de recherche En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-70.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55115 Exemplaires(2)
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