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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)
Code-barres Cote Support Localisation Section Disponibilité 15261-01 30.70 Livre Centre de documentation Géodésie Disponible 15261-02 30.70 Livre Centre de documentation Géodésie Disponible
Titre : Absolute airborne gravimetry Type de document : Thèse/HDR Auteurs : Henri Baumann, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2005 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 69 Importance : 142 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-12-3 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] accélération
[Termes IGN] étude de faisabilité
[Termes IGN] GPS-INS
[Termes IGN] gravimètre absolu
[Termes IGN] gravimétrie aérienne
[Termes IGN] traitement de donnéesIndex. décimale : 30.42 Gravimétrie Résumé : (Auteur) This work consists of a feasibility study of a first stage prototype airborne absolute gravimeter system. In contrast to relative systems, which are using spring gravimeters, the measurements acquired by absolute systems are uncorrelated and the instrument is not suffering from problems like instrumental drift, frequency response of the spring and possible variation of the calibration factor. The major problem we had to resolve were to reduce the influence of the non-gravitational accelerations included in the measurements. We studied two different approaches to resolve it: direct mechanical filtering, and post-processing digital compensation.
The first part of the work describes in detail the different mechanical passive filters of vibrations, which were studied and tested in the laboratory and later in a small truck in movement. For these tests as well as for the airborne measurements an absolute gravimeter FG5-L from Micro-G Ltd was used together with an Inertial navigation system Litton-200, a vertical accelerometer EpiSensor, and GPS receivers for positioning. These tests showed that only the use of an optical table gives acceptable results. However, it is unable to compensate for the effects of the accelerations of the drag free chamber.
The second part describes the strategy of the data processing. It is based on modeling the perturbing accelerations by means of GPS, EpiSensor and INS data.
In the third part the airborne experiment is described in detail, from the mounting in the aircraft and data processing to the different problems encountered during the evaluation of the quality and accuracy of the results. In the part of data processing the different steps conducted from the raw apparent gravity data and the trajectories to the estimation of the true gravity are explained. A comparison between the estimated airborne data and those obtained by ground upward continuation at flight altitude allows to state that airbome absolute gravimetry is feasible and has a spatial resolution comparable to the one of the relative airborne gravimetry. For a wavelength on the order of 11 km the mean value of the resolution of the estimated gravity is 9.7 mGal.
Finally some suggestions are formulated for the improvement of the system which should simplify its use, increase the accuracy and reduce its price.Numéro de notice : 13266 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-004701048 Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD thesis : Géodésie et photogrammétrie : ETH Zurich : 2005 DOI : 10.3929/ethz-a-004701048 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-69.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54947 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 13266-01 30.42 Livre Centre de documentation Géodésie Disponible 13266-02 30.42 Livre Centre de documentation Géodésie Disponible
Titre : Geodetic mobile solar spectrometer [GEMOSS] Type de document : Thèse/HDR Auteurs : Alexander Somieski, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2005 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 68 Projets : Gavdos / Importance : 205 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-11-6 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Rayonnement électromagnétique
[Termes IGN] campagne d'expérimentation
[Termes IGN] positionnement par GPS
[Termes IGN] propagation troposphérique
[Termes IGN] spectromètre
[Termes IGN] spectroscopie
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] troposphèreIndex. décimale : 24.30 Rayonnement électromagnétique Résumé : (Auteur) The goal of this work was to develop a portable prototype of a solar spectrometer for the determination of tropospheric water vapor with a high precision as needed for geodetic applications. It was realized in the construction of the "GEodetic MObile Solar Spectrometer" (GEMOSS), which allows the simultaneous measurement of numerous single vibrational-rotational absorption lines in the wide wavelength range between 728 nm and 915 nm.
In order to achieve the wide wavelength range and the envisaged high measurement accuracy, a new optical layout of a high-resolution echelle spectrograph was applied. Furthermore, its instrumental characteristics were determined and considered in the analysis and simulation of the spectrum. Therefore, investigations were carried out concerning hardware requirements, appropriate spectral intervals, stabilization of the wavelength scale, determination of the apparatus function and stray light. In addition to the theoretical aspects of molecular absorption and emission in Earth's atmosphere, the meteorological model, ray tracing and the current state of molecular spectroscopie databases were examined. Furthermore, an algorithm for retrieving the integrated precipitable water vapor (PW) from GEMOSS spectra was developed. It is based on the "Differential Optical Absorption Spectroscopy" (DOAS) and includes the simulation of synthetic solar spectra. For the simulation the line strength parameters of H20 absorption lines were taken frorn the molecular spectroscopie database by the European Space Agency (ESA). Although the line strength parameters, which have a large impact on the accuracy of the simulated spectra and the retrieved PW, were improved during the last years, they still reveal significant errors. The wide spectral range of GEMOSS enables the accurate correction of those parameters using solar spectra measured at atmospheric conditions controlled by radiosonde soundings and a water vapor radiometer (WVR). For this purpose, a dedicated campaign was carried out at the meteorological station at Payerne (Switzerland) in May and June 2004. CEMOSS and a co-located WVR were deployed next to a Global Positioning Systern (GPS) receiver of the Automated GPS Network of Switzerland (AGNES). The acquired dataset was utilized to improve line strength parameters of 69 individual transitions of the H20 molecule between 732 mn and 906 nm.
In order to validate the performance of GEMOSS, a long-term series of PW was acquired at ETH Hönggerberg where a permanent GPS station (AGNES) is operated. With the utilization of up to 40 selected H20 absorption lines measured at the same time, an accuracy of the PW of 0.5 kg/m can be achieved. The comparison between GEMOSS and GPS revealed that GPS over-estimated the PW during the summer 2003 by about 2-3 kg/m . The same discrepancies were observed at Payerne in 2004 by comparing the GPS results with GEMOSS, WVR and radiosondes.
In the framework of the EU-project "GAVDOS", GEMOSS was operated under the track of the altimeter satellite Jason at Rethimnon (Crete, Greece) and at Fiskardo on the island of Kefalonia (Greece) in January and September in 2003. The highly precise PW measurements of GEMOSS were used to calibrate the on-board microwave radiometer of Jason (JMR). The integrated water vapor content which was simultaneously determined by GEMOSS and JMR agree at the 0.3-0.4 kg/m level. On the basis of these promising results GEMOSS can be considered as a novel portable tool for space-borne radiometer calibration and it will be deployed for further calibration of Jason in the future.Numéro de notice : 13265 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse étrangère DOI : 10.3929/ethz-a-004930678 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-68.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54946 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 13265-01 24.30 Livre Centre de documentation Physique Disponible 13265-02 24.30 Livre Centre de documentation Physique Disponible GPS based determination of the integrated and spatially distributed water vapor in the troposphere / Marc Troller (2004)
Titre : GPS based determination of the integrated and spatially distributed water vapor in the troposphere Type de document : Thèse/HDR Auteurs : Marc Troller, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2004 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 67 Importance : 172 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-10-9 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] correction troposphérique
[Termes IGN] distribution spatiale
[Termes IGN] modèle atmosphérique
[Termes IGN] positionnement par GPS
[Termes IGN] propagation troposphérique
[Termes IGN] Suisse
[Termes IGN] teneur en vapeur d'eau
[Termes IGN] tomographie
[Termes IGN] traitement du signal
[Termes IGN] troposphère
[Termes IGN] vapeur d'eauIndex. décimale : 30.84 Applications de géodésie spatiale à l'atmosphère Résumé : (Auteur) Climate change and global warming have become a major challenge for the sustainable development of our Earth and its environment. Intensive research is carried out to understand atmospheric processes and their implications. In this content, water vapor plays a key role. It is an important component of the global energy balance and is involved in many chemical reactions. In microwave measurements, the tropospheric refractivity causes a delay in the arrival of the signal propagating through the atmosphere. This refraction effect is one of the limiting factors in accurate GPS positioning. The tropospheric path delay can be decomposed into a dry and wet part, where the latter part is coupled with the integrated precipitable water vapor above the GPS receiver.
On the one hand, the refraction effect has to be corrected for GPS measurements, on the other hand, it is a valuable signal to determine the spatial distribution of the water vapor. This study investigates both aspects. For the first part, two basic approaches are looked into: One method is based on meteorological measurements. Thereby, the integrated amount of water vapor and its temporal variation are the prime target. The other concept makes use of long-term GPS measurements. The arrival delay of the GPS signals are used, to estimate the integrated amount of water vapor. This result can then be the basis to determine its spatial distribution and temporal behavior. The investigation is based on a tomographic approach and forms the main content of part 2 of this work.
In part 1, an extension of the software package COMEDIE is developed and applied to determine tropospheric path delays. COMEDIE allows a four-dimensional modeling (in space and time) of the meteorological parameters air pressure, temperature and water vapor pressure using a collocation approach. Integrating the meteorological parameters, tropospheric path delays are obtained. Evaluations and comparisons in Switzerland show the performance of this method. An overall good agreement was achieved compared to GPS-estimated path delays. The accuracy depends on the season, and is in the range of 1-2 cm for the tropospheric path delay.
Continuous GPS measurements allow to estimate tropospheric path delays in the GPS processing. In a second approach of part 1, a method based on such GPS-estimated path delays is developed. It uses - like COMEDIE - a four-dimensional model and a collocation adjustment to estimate tropospheric path delays at desired locations. Evaluations are carried out in the area of Switzerland using the permanent GPS network AGNES. Long-term time series of cross-correlations are analyzed. An accuracy of 0.5 - 1.5 cm is obtained.
To resolve the GPS-estimated water vapor in the vertical, a tomographic approach is investigated in part 2 of this study. It is based on the assimilation of GPS double-difference observations. The wet refractivity field is determined applying a least-squares adjustment. To test the performance of the software, different weather conditions are simulated. Various stochastically constrained models are applied and discussed in terms of inversion stability. Results from real data gathered during a dedicated measurement campaign in the high density GPS network of the Big Island of Hawaii are analyzed. Compared to radiosondes, an accuracy of about 10 ppm (refractivity units) is achieved.
To compare the potential and limits of the investigated methods, independent data must be available. An extensive study is performed in the area of Switzerland to evaluate and compare all presented methods with each other. For the validation, data of the numerical weather model aLMo are used. Seven days of data in a high spatial distribution and on an hourly basis are investigated. The tropospheric path delays resulting from the various methods are compared and analyzed. An overall good agreement with the aLMo data was observed. To evaluate the spatial distribution of water vapor, 7680 refractivity profiles are determined with the tomographic method and compared with the numerical weather data. The analysis contains four tomographic approaches including different types of constraints. The results are statistically evaluated and compared. A correlation between the accuracy and the weather situation was found. Overall, an agreement of 5-7 ppm (refractivity units) was achieved compared to aLMo.
In conclusion, it can be stated that the determination of the integrated amount of water vapor in the troposphere was successfully performed. For the main geodetic application, the correction of GPS measurements, the estimation of path delays in the GPS processing is recommended, provided long-terrn GPS phase observations are available. For the determination of the spatial distribution and the temporal variation of the integrated amount of water vapor, modeling of the GPS-estimated path delays is a successful method. Moreover, the principal feasibility to resolve the vertical distribution of the water vapor applying the tomographic approach was demonstrated. However, further investigations concerning constraints or the introduction of additional information are required.Numéro de notice : 13264 Affiliation des auteurs : non IGN Autre URL associée : http://dx.doi.org/10.3929/ethz-a-004796376 Thématique : POSITIONNEMENT Nature : Thèse étrangère DOI : 10.3929/ethz-a-004796376 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-67.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=54945 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 13264-01 30.84 Livre Centre de documentation Géodésie Disponible 13264-02 30.84 Livre Centre de documentation Géodésie Disponible
Titre : Capteurs et algorithmes pour la localisation autonome en mode pédestre Type de document : Monographie Auteurs : Q. Ladetto, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2003 Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 66 Importance : 102 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-05-5 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] accéléromètre
[Termes IGN] champ magnétique local
[Termes IGN] dynamique spatiale
[Termes IGN] géopositionnement tridimensionnel
[Termes IGN] gyroscope
[Termes IGN] navigation pédestre
[Termes IGN] nivellement barométrique
[Termes IGN] positionnement par GPS
[Termes IGN] traitement du signal
[Termes IGN] vitesseIndex. décimale : 30.70 Navigation et positionnement Résumé : (Auteur) Connaître sa position de façon précise et fiable, en tout temps, avec et sans réception de signaux satellitaires, représente une problématique passablement explorée pour la navigation de véhicules. Élargir ce service aux piétons nécessite une approche différente1 adaptée à la dynamique, à la vitesse et surtout à la totale liberté de mouvement que favorise la marche à pied. La mécanisation classique consistant en une double intégration de l'accélération jointe à une intégration de la vitesse angulaire pour obtenir une position n'est malheureusement pas judicieuse pour des systèmes bon marché. La raison principale est que la vitesse de déplacement d'une personne se trouve noyée dans la plage de bruit du capteur. Afin de tenir compte de toutes ces spécificités, une approche événementielle, remplaçant celle mentionnée ci-dessus et dite temporelle, fut développée. Celle-ci fait appel à diverses technologies ainsi qu'à une approche physiologique et biomécanique de la marche, scindant cette recherche en trois parties principales.
La première étape consiste en la détermination des principaux paramètres physiologiques utiles à la quantification de la vitesse et de la taille des pas. Si l'agitation des signaux accélérométriques se veut un bon indicateur de la vitesse, la fréquence des pas améliore la robustesse du modèle. L'influence du genre de la personne s'additionnant à la grande diversité humaine, une normalisation des différentes relations est nécessaire. De nombreux essais réalisés dans des conditions de la vie de tous les jours montrent que la variation de la taille des pas en fonction de la pente dépend fortement de la condition physique de l'individu ainsi que de la durée de l'ascension ou de la descente. Une personne pouvant se déplacer en avant, en arrière et latéralement, les motifs caractéristiques de ces mouvements-types on été identifiés. Les divers modèles suggérés furent testés ensuite favorablement avec des aveugles dont la marche varie fortement en fonction du niveau de confiance envers le parcours effectué.
La deuxième partie concerne directement les multiples technologies nécessaires à une localisation tri-dimensionnelle autonome. La connaissance du champ magnétique terrestre et de son orientation permet de déterminer l'azimut de déplacement de la personne. L'utilisation d'un gyroscope améliore la fiabilité du système tout en facilitant la détection et la mitigation de l'influence des perturbations magnétiques. Plus stable à court terme que le compas, celui-ci en est donc le complément idéal dans de telles circonstances. L'information altimétrique s'obtient par mesures barométriques qui, selon le degré de précision désiré, peuvent être différentielles. L'utilisation d'un récepteur GPS permet une localisation absolue ainsi que le calibrage des erreurs des divers senseurs et des modèles physiologiques.
Le troisième chapitre décrit le processus d'intégration des modèles et mesures utilisées de même que les caractéristiques et traitements spécifiques à la navigation pédestre. Une phase d'initialisation est présentée afin de déterminer les spécificités du mouvement de chacun et d'adapter ainsi individuellement les paramètres de marche. La détection du déplacement couplée à celle de la direction permet une détermination et un filtrage optimal de l'azimut ne présentant que peu ou pas de dégradation temporelle. La prise en compte de divers phénomènes propres aux déplacements des êtres humains permet à l'intelligence artificielle d'améliorer la navigation pédestre. Le couplage des diverses sources de mesures ainsi que leur précision et implication sur la fiabilité de l'information fournie sont décrits et illustrés. Plus de 550 km parcourus dans diverses circonstances avec 31 personnes différentes ont permis de valider l'approche présentée tout en fixant ses limites.Numéro de notice : 15140 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Monographie En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-66.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=55073 Exemplaires(2)
Code-barres Cote Support Localisation Section Disponibilité 15140-01 30.70 Livre Centre de documentation Géodésie Disponible 15140-02 30.70 Livre Centre de documentation Géodésie Disponible Efficient methods for determining precise orbits of low earth orbiters using the Global Positioning System / Heike Bock (2003)PermalinkPermalinkAnalysis of refraction influences in geodesy using image processing and turbulence models / Philipp Flach (2001)PermalinkPermalinkSpatial and temporal distribution of atmospheric water vapor using space geodetic techniques / Lars Peter Kruse (2001)PermalinkModeling and validating orbits and clocks using the Global Positioning System / Tim A. Springer (2000)PermalinkMapping and predicting the Earth's ionosphere using the Global Positioning System / Stefan Schaer (1999)PermalinkPermalinkSystematic investigations of error- and system-modelling of satellite based flight approaches and landing in Switzerland / M. Scaramuzza (1998)PermalinkPermalink
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