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Titre : Advanced modeling and algorithms for high-precision GNSS analysis Type de document : Thèse/HDR Auteurs : Kan Wang, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2016 Collection : Dissertationen ETH num. 23188 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Termes IGN] ambiguïté entière
[Termes IGN] antenne GPS
[Termes IGN] centre de phase
[Termes IGN] données BeiDou
[Termes IGN] données Galileo
[Termes IGN] données GPS
[Termes IGN] double différence
[Termes IGN] erreur systématique
[Termes IGN] GPS en mode différentiel
[Termes IGN] horloge
[Termes IGN] phase GNSS
[Termes IGN] positionnement cinématique
[Termes IGN] récepteur GNSS
[Termes IGN] récepteur trifréquence
[Termes IGN] résolution d'ambiguïté
[Termes IGN] retard ionosphèrique
[Termes IGN] Suisse
[Termes IGN] trajet multiple
[Vedettes matières IGN] Traitement de données GNSSRésumé : (auteur) In the recent ten years, the Global Navigation Satellite System (GNSS) processing has experienced a fast development in many areas including the increasing number of frequencies, the higher quality of positioning instruments, e.g. the receiver clocks and the satellite clocks, and more integrated modeling and calculation strategies. This thesis includes investigations of different modeling and parameterization methods in modern GNSS positioning with the focus on three important positioning error sources: the receiver clock errors, the phase ambiguities and the ionospheric delays.
The thesis shows that making use of the high-quality receiver clocks and applying appropriate receiver clock modeling can help to improve the kinematic height estimates, which are highly correlated with the receiver clock parameters. An efficient pre-elimination and back-substitution strategy of epoch parameters with relative clock constraints between subsequent and near-subsequent epochs has been developed to enable processing of, e.g., high-rate data. A detailed analysis of the relationship between the clock quality and the improvement of kinematic heights has been performed. Studies were also conducted to decorrelate the receiver clock parameters, the kinematic heights and the troposphere parameters. Experiments with real data have shown that appropriate deterministic and stochastic clock models can also be helpful to increase the resolution of the estimated Zenith Path Delay (ZPD) parameters without obvious degradation of the stability of the kinematic heights.
The second aspect of the thesis focuses on the resolution of triple-frequency phase ambiguities with different linear combinations. A complete analytical investigation of Geometry-Free (GF) and Ionosphere-Free (IF) triple-frequency phase ambiguity resolution with minimized noise level has been performed for different frequency triplets. The analysis was done separately for the best two linear combinations and the third one. Experiments have shown that the fractional parts and the formal errors of the combined ambiguities of the best two linear combinations are relatively small for Galileo E1, E5b and E5a and GPS L1, L2 and L5 triplets, while the third linear combination remains a challenge. Further analysis with the geostationary satellites of the Beidou Navigation Satellite System (BDS) elaborated in the framework of this thesis has also confirmed that the combined ambiguities from the best two GF and IF linear combinations can be fixed by rounding, while the estimated ambiguities on L1 have relatively large deviations from the values obtained from the traditional dual-frequency double-difference ambiguity resolution. Apart from the triple-frequency ambiguity resolution on the double-difference level, the so-called track-to-track ambiguities between different tracks of the same receiver and the same satellite have also been investigated for the best two triple-frequency linear combinations using GPS L1, L2 and L5 as well as Galileo E1, E5b and E5a observations. The outcome demonstrates that elevation-dependent influences on the observations like Phase Center Variations (PCVs), Phase Center Offsets (PCOs) and multipath are important for the fixing of the track-to-track ambiguities.
The combined track-to-track ambiguities using the best two linear combinations are also effective in detecting problems in the observation data.
The third aspect of the thesis includes the investigation of the differential ionospheric delays and gradients in the region of Switzerland from 1999 to 2013. In differential Global Positioning System (GPS) positioning, the ionospheric delays for short baselines are in most cases small enough to be ignored, except under extreme conditions, e.g., during ionospheric stormy days, and for applications with high integrity requirements, e.g., during approach and landing of aircrafts. This thesis introduces an algorithm using double-difference phase measurements with resolved phase ambiguities and global ionosphere maps provided by the Center for Orbit Determination in Europe (CODE) to extract the single-difference ionospheric delays, and enabling an automatic and robust processing of the data over 15 years. The results show that the daily maximum slant ionospheric gradients calculated from the differential slant ionopheric delays and the baseline lengths from 1999 to 2013 are below the slant ionosphere gradient boundary of the Conterminous United States (CONUS) ionospheric anomaly threat model.Numéro de notice : 17250 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : dissertation : sciences : ETH Zurich : 2016 En ligne : http://dx.doi.org/10.3929/ethz-a-010610972 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81986 Autonomous navigation in complex nonplanar environments based on laser ranging / Philipp Andreas Krüsi (2016)
Titre : Autonomous navigation in complex nonplanar environments based on laser ranging Type de document : Thèse/HDR Auteurs : Philipp Andreas Krüsi, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2016 Note générale : bibliographie
A thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Lasergrammétrie
[Termes IGN] algorithme ICP
[Termes IGN] données lidar
[Termes IGN] données localisées 3D
[Termes IGN] navigation autonome
[Termes IGN] robot mobile
[Termes IGN] semis de points
[Termes IGN] télémètre laser
[Termes IGN] télémétrie laser aéroporté
[Termes IGN] télémétrie laser terrestre
[Termes IGN] temps réel
[Termes IGN] vision par ordinateurRésumé : (auteur) This thesis addresses the problem of autonomous navigation with ground robots in complex environments, which may be characterized as nonplanar and nonstatic. The goal of the presented research is to enable reliable navigation over large distances in generic indoor and outdoor environments, independent of external localization sources such as a global positioning system (GPS). Focusing on these challenges, algorithms for all building blocks of autonomous navigation—localization, mapping, terrain assessment, motion planning, and motion control—are developed, implemented, integrated, and finally evaluated in extensive field experiments. Sensor-based perception of the environment is a basic requirement for localization and mapping. We propose to use a high-frequency three-dimensional (3D) laser scanner as the main exteroceptive sensor. The advantages of this technology lie in the high density and accuracy of the provided measurements, and their independence of lighting and weather conditions. We develop a highly scalable system for six-dimensional (6D) localization and 3D mapping based on iterative closest point (ICP) matching. A topological/metric map representation, where metric information is kept in spatially constrained local submaps representing vertices in a graph, allows to build consistent large-scale maps without requiring global optimization. Long-term application in dynamic and changing environments is enabled by integrating methods for identifying dynamic objects in the scene and for continuously updating existing submaps. Planning feasible and safe motions for a robotic vehicle requires distinguishing obstacles from traversable terrain. We develop two different algorithms for terrain assessment. The first method is targeted at real-time obstacle detection in the vicinity of the robot. Assuming locally planar terrain, a grid-based obstacle map is built by analyzing the raw laser scans. The second approach is based on dense point cloud maps (which can be obtained from the ICP mapping system) and suitable for planar and nonplanar environments. The algorithm computes the geometry and the traversability of the terrain “on demand” at specific query locations, avoiding any artificial discretization or explicit surface reconstruction. The desired terrain characteristics are estimated based on statistics on the local distribution of map points. Given a specific navigation task, motion planning can be defined as the problem of reasoning about how to act based on the knowledge about the environment. This thesis addresses both local obstacle avoidance and global planning over large distances. Our approach to local planning consists of computing a set of candidate trajectories, which are shaped around nearby obstacles or along a given reference path, and enforced to satisfy the robot’s kinematic constraints. The optimal local trajectory is chosen by evaluating the motion alternatives in terms of guidance towards the goal and traversability of the underlying terrain. For global motion planning, we develop an algorithm embedding the proposed point-cloud-based terrain assessment method, which allows trajectories to be directly planned on 3D point cloud maps. The approach is designed to be suitable for generic nonplanar environments, including rough outdoor terrain, multi-level facilities, and more complex geometries. Piecewise continuous trajectories are computed in the full 6D space of robot poses, while strictly considering the vehicle’s kinematic and dynamic constraints. We apply sampling-based planning algorithms to generate an initial trajectory connecting the desired start and goal poses. Subsequently, the trajectory is locally optimized according to a generic cost function, which may include path length, path curvature, and roughness of the traversed terrain. While enforcing the hard constraints to remain satisfied (terrain contact, traversability, kinodynamic feasibility), the trajectory is iteratively deformed until a local minimum of the cost function is reached. We develop two complete systems for autonomous navigation, integrating these approaches. Combining the ICP-based localization and mapping framework with local obstacle detection and local motion planning, we implement a framework for autonomous route following, commonly referred to as teach and repeat (T&R). After a manually controlled teach run, where a graph of local submaps is built, the robot is able to automatically repeat the learned route, using the recorded maps for localization. Unlike classical T&R systems, our framework is suitable for application in dynamic environments, where the integrated obstacle avoidance scheme allows to detect and circumnavigate obstacles appearing on the reference path. In addition to the T&R approach, we present a second navigation system, integrating the point-cloud-based terrain assessment and global planning algorithms with ICP-based localization and mapping. Given a graph of point cloud maps—typically recorded in a manually controlled survey run—the framework enables navigation within the mapped area without being restricted to known routes. Motion control is implemented by a trajectory tracking controller with integrated real-time collision checking. Together with continuous map updates and frequent replanning of the global trajectory, these techniques enable autonomous navigation in nonplanar, nonstatic environments. Finally, we describe the characteristics of the mobile robot ARTOR, which was set up for the purpose of testing and evaluating the developed algorithms under realistic conditions. ARTOR consists of a six-wheeled, electrically powered base vehicle equipped with sensors, computers, and communication gear. The proposed autonomous navigation algorithms were integrated on the robot and tested in extensive field experiments, demonstrating reliable, GPS-independent navigation over large distances and under greatly varying environmental conditions, in unstructured off-road terrain, multi-level environments, and dynamic urban areas. Numéro de notice : 17367 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Thèse étrangère Note de thèse : PhD thesis : Sciences : ETH Zurich : 2016 En ligne : http://dx.doi.org/10.3929/ethz-a-010656081 Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=84243
Titre : Co-location of geodetic observation techniques in space Type de document : Thèse/HDR Auteurs : Benjamin Männel, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2016 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 97 Importance : 200 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-43-7 Note générale : bibliographie
A thesis submitted to attain the degree of Doctor of Sciences of ETH Zurich (Eidg. Technische Hochschule Zürich)Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GPS
[Termes IGN] Bernese
[Termes IGN] centre de phase
[Termes IGN] co-positionnement
[Termes IGN] données GRACE
[Termes IGN] géocentre
[Termes IGN] interférométrie à très grande base
[Termes IGN] International Terrestrial Reference System
[Termes IGN] orbite basse
[Termes IGN] orbitographie
[Termes IGN] positionnement par GPS
[Termes IGN] poursuite de satellite
[Termes IGN] propagation ionosphérique
[Termes IGN] repère de référence
[Termes IGN] système international de référence célesteIndex. décimale : 30.60 Géodésie spatiale Résumé : (auteur) This thesis describes the combination of geodetic observation techniques on-board satellites. This socalled co-location in space provides a considerable potential regarding the improvements needed to realize a long-term accurate and stable terrestrial reference frame. The space ties (i.e., the offset vectors between the on-board sensors) introduces new geometrical connections between sensors of dfferent space geodetic techniques. This space ties can be provided easily to each fundamental site via space geodetic observations. Consequently, co-location in space allows to assess technique-specific error sources as systematic effects can be addressed either to a certain station or to a certain technique. Moreover, the additional introduced orbit dynamics improve the estimation of several geodetic parameters. Within this thesis the following core topics concerning co-location in space are discussed: orbit determination, the combination of ground and space GNSS observations, and VLBI Earth-orbiting satellite tracking. Highly accurate orbit determination is the prerequisite for a suitable co-location in space. Based on the Earth observation satellite missions GRACE, GOCE, and OSTM/Jason-2 orbit determination and the impact of modeling non gravitational perturbations is studied. The overall reached orbit accuracies are at the level of a few centimeters. The combination of ground and space-geodetic GNSS observations is studied based on the GPS observations derived by 53 ground stations and the four LEOs (low Earth orbiter). Adding one LEO to the ground-only processing decreases the formal errors of weekly geocenter estimates by around 20% which is eight times more than expected due to the increased number of observations. This shows the considerable potential of the combination of ground and LEO data. Comparing the derived geocenter time series against results from satellite laser ranging (SLR) shows a good agreement for annual amplitudes, whereas the annual phases shows considerable discrepancies in the x- and the z-component. Geocenter coordinates derived from surface load density coeficients estimated in a long-term solution show a better agreement to SLR solutions but without a significant impact of additional LEOs. Using the gravitational constraint GPS satellite antenna phase center offsets were estimated based on ground and LEO observations. The results show a significant benefit for the horizontal offsets as the introduced LEOs help to dissolve limiting correlations. Concerning single-frequency VLBI satellite tracking the L4R method is introduced to derive ionosphere delay corrections based on co-located GNSS observations. A 1 cm daily station coordinate repeatability is achieved in a single-frequency GNSS processing while introducing the L4R corrections. Differences to ionospheric delays derived from VLBI observations show also a good agreement. As VLBI satellite tracking is currently in an experimental stage Monte-Carlo simulations were performed for eight different satellite orbit types. For a GNSS constellation tracking, station coordinate repeatabilities are at the level of 0.7 and 1.2 cm for a regional and a global network, respectively. Station coordinate repeatabilities of around 1 cm were derived for simulated VLBI observation to a fictitious LEO with an altitude of 2000 km. The station coordinates estimated from simulated observations to E-GRIP and E-GRASP/Eratosthenes show larger uncertainties. Based on the results suggestions for future action items regarding co-location in space were formulated. The most important recommendations are, that the combination of ground- and space GNSS observations provides a considerable benefit for the determination of several parameters and that ionosphere delay corrections should be derived from co-located GNSS observations. Note de contenu : 1- Motivation and Introduction
2- Geodetic Observation Techniques in a Nutshell
3- Reference Systems and the Combination and Co-location of Space Geodetic Techniques
4- Investigations on GPS-based Precise Orbit Determination for Low Earth Orbiters
5- Investigations on the Combined Processing of Ground- and Space-based GPS Observations
6- Investigations on VLBI Satellite Tracking
7- Conclusions and OutlookNuméro de notice : 21987 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD : Sciences : ETH Zurich : 2016 DOI : 10.3929/ethz-a-010811791 En ligne : https://www.research-collection.ethz.ch/handle/20.500.11850/125751 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=91982 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 21987-01 30.70 Livre Centre de documentation Géodésie Disponible Real-time depth-image-based rendering for viewpoint-variable display on mobile devices / Shuoran Yang (2016)
Titre : Real-time depth-image-based rendering for viewpoint-variable display on mobile devices Type de document : Mémoire Auteurs : Shuoran Yang, Auteur Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Année de publication : 2016 Importance : 36 p. Format : 21 x 30 cm Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] appareil portable
[Termes IGN] petit écran
[Termes IGN] réalité augmentée
[Termes IGN] rendu réaliste
[Termes IGN] temps réel
[Termes IGN] visualisation de données
[Vedettes matières IGN] GéovisualisationIndex. décimale : 37.60 Géovisualisation Résumé : (auteur) The ability to adjust the display according to the user viewpoint gives a more immersive user experience to augmented reality applications. In this thesis, we propose a pipeline for rendering images to variable viewpoints from a video captured on a mobile device with an arbitrarily aligned camera sensor. We present algorithms to handle depth map restoration, disocclusion and synchronization issues to minimize artifacts in the rendering of virtual images. This pipeline is implemented in the Project Tango framework where an RGB-IR pixel sensor is used to capture depth map and color image inputs. At the end, we demonstrate the results with a video recorded on the Project Tango tablet. The results show that the pipeline is capable of rendering realistic images that have the potential of being used for augmented reality applications. Numéro de notice : 17204 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Mémoire masters divers En ligne : http://dx.doi.org/10.3929/ethz-a-010634330 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81185 Study and development of a laser based alignment system for the compact linear collider / Guillaume Stern (2016)
Titre : Study and development of a laser based alignment system for the compact linear collider Type de document : Thèse/HDR Auteurs : Guillaume Stern, Auteur Editeur : Zurich : Schweizerischen Geodatischen Kommission / Commission Géodésique Suisse Année de publication : 2016 Autre Editeur : Zurich : Eidgenossische Technische Hochschule ETH - Ecole Polytechnique Fédérale de Zurich EPFZ Collection : Geodätisch-Geophysikalische Arbeiten in der Schweiz, ISSN 0257-1722 num. 96 Importance : 230 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-908440-42-0 Note générale : bibliographie
thesis submitted to attain the degree of doctor of sciences of ETH ZurichLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Acquisition d'image(s) et de donnée(s)
[Termes IGN] accélérateur de particules
[Termes IGN] caméra numérique
[Termes IGN] capteur actif
[Termes IGN] laser
[Termes IGN] topométrie de précisionIndex. décimale : 35.10 Acquisition d'images Résumé : (auteur) The first objective of the PhD thesis is to develop a new type of positioning sensor to align components at micrometre level over 200 m with respect to a laser beam as straight line reference. The second objective is to estimate the measurement accuracy of the total alignment system over 200 m. The context of the PhD thesis is the Compact Linear Collider project, which is a study for a future particle accelerator.
The proposed positioning sensor is made of a camera and an open/close shutter. The sensor can measure the position of the laser beam with respect to its own coordinate system. To do a measurement, the shutter closes, a laser spot appears on it, the camera captures a picture of the laser spot and the coordinates of the laser spot centre are reconstructed in the sensor coordinate system with image processing. Such a measurement requires reference targets on the positioning sensor.
To reach the first objective of the PhD thesis, we used laser theory and camera model to define an accurate image processing and we performed experiments to validate a prototype of a positioning sensor. For the second objective, we could not obtain results regarding measurement accuracy because we could not develop a full alignment system under vacuum over 200 m. However, we could estimate laser pointing stability over 200 m by extrapolating results obtained over 12 m.
As a result, we present in this report a sensor design, a calibration protocol and estimations regarding measurement uncertainty. In case of a separate calibration with theodolites, we estimated the measurement uncertainty of the positioning sensor to be 4μm for all coordinates. In case of a full auto-calibration, we estimated the measurement uncertainty of the positioning sensor to be 10μm for the radial and the vertical coordinates and 20μm for the depth coordinate. Concerning the extrapolation over long distance, we estimated laser pointing stability to be 10μm for a laser beam propagation distance of 200 m.
Our work does not provide a complete laser beam alignment system at micrometre level over 200 m but it is the first necessary step towards it.Note de contenu : 1 - Introduction
2 - Theoretical background
3 - Experiments
4 - Sensor implementation
5 - ConclusionNuméro de notice : 17460 Affiliation des auteurs : non IGN Autre URL associée : URL supplémentaire Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : thèse : Sciences : ETHZ : 2016 DOI : 10.3929/ethz-a-010621412 En ligne : https://www.sgc.ethz.ch/sgc-volumes/sgk-96.pdf Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89686 Réservation
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