The Experts below are selected from a list of 1782 Experts worldwide ranked by ideXlab platform
Zaher M Kassas - One of the best experts on this subject based on the ideXlab platform.
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Pseudorange Measurement outlier detection for navigation with cellular signals wip abstract
International Conference on Cyber-Physical Systems, 2019Co-Authors: Mahdi Maaref, Joe Khalife, Zaher M KassasAbstract:We present an autonomous Measurement outlier detection and exclusion framework for ground vehicle navigation using cellular signals of opportunity (SOPs) and an inertial Measurement unit (IMU). The experimental results demonstrate the proposed framework successfully detecting and excluding outlier Measurements, improving the position root mean-squared error (RMSE) by 42%. The demo session will showcase work in progress, namely (1) demo (in the form of a video of our experiment driving in downtown Riverside, California) and (2) a poster that includes the navigation framework, the proposed outlier detection method, and the experimental results.
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ICCPS - Pseudorange Measurement outlier detection for navigation with cellular signals: WIP abstract
Proceedings of the 10th ACM IEEE International Conference on Cyber-Physical Systems, 2019Co-Authors: Maaref, Joe Khalife, Zaher M KassasAbstract:We present an autonomous Measurement outlier detection and exclusion framework for ground vehicle navigation using cellular signals of opportunity (SOPs) and an inertial Measurement unit (IMU). The experimental results demonstrate the proposed framework successfully detecting and excluding outlier Measurements, improving the position root mean-squared error (RMSE) by 42%. The demo session will showcase work in progress, namely (1) demo (in the form of a video of our experiment driving in downtown Riverside, California) and (2) a poster that includes the navigation framework, the proposed outlier detection method, and the experimental results.
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a framework for navigation with lte time correlated Pseudorange errors in multipath environments
Vehicular Technology Conference, 2019Co-Authors: Kimia Shamaei, Joshua J Morales, Zaher M KassasAbstract:A navigation framework based on a multi-state constraint Kalman filter (MSCKF) is proposed to reduce the effect of time-correlated Pseudorange Measurement noise of cellular long-term evolution (LTE) signals. The proposed MSCKF framework captures the position of the antenna over a window of Measurements to impose constraints on the position estimate. Simulation results are presented showing a reduction of 57% and 51% in the two- dimensional (2D) and three-dimensional (3D) position root mean squared-error (RMSE), respectively, using the proposed framework compared to an extended Kalman filter (EKF). Experimental results on a ground vehicle navigating in an urban environment are presented showing a reduction of 29% and 64.7% in the 2D and 3D position RMSE, respectively, and a reduction of 19.6% and 86.7% in the 2D and 3D maximum error, respectively, using the proposed framework compared to an EKF.
Salvatore Gaglione - One of the best experts on this subject based on the ideXlab platform.
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A resampling strategy based on bootstrap to reduce the effect of large blunders in GPS absolute positioning
Journal of Geodesy, 2018Co-Authors: Antonio Angrisano, Antonio Maratea, Salvatore GaglioneAbstract:In the absence of obstacles, a GPS device is generally able to provide continuous and accurate estimates of position, while in urban scenarios buildings can generate multipath and echo-only phenomena that severely affect the continuity and the accuracy of the provided estimates. Receiver autonomous integrity monitoring (RAIM) techniques are able to reduce the negative consequences of large blunders in urban scenarios, but require both a good redundancy and a low contamination to be effective. In this paper a resampling strategy based on bootstrap is proposed as an alternative to RAIM, in order to estimate accurately position in case of low redundancy and multiple blunders: starting with the Pseudorange Measurement model, at each epoch the available Measurements are bootstrapped—that is random sampled with replacement—and the generated a posteriori empirical distribution is exploited to derive the final position. Compared to standard bootstrap, in this paper the sampling probabilities are not uniform, but vary according to an indicator of the Measurement quality. The proposed method has been compared with two different RAIM techniques on a data set collected in critical conditions, resulting in a clear improvement on all considered figures of merit.
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GIOVE Satellites Pseudorange Error Assessment
Journal of Navigation, 2011Co-Authors: Antonio Angrisano, Salvatore Gaglione, Umberto Robustelli, Ciro Gioia, Mario VultaggioAbstract:Galileo is a global civil navigation satellite system developed in Europe as an alternative to the GPS controlled by the US Department of Defense and GLONASS controlled by Russian Space Forces. It is scheduled to be operative in 2013 and it will have 30 satellites orbiting on three inclined planes with respect to the equatorial plane at an altitude of about 24 000 km. The aim of this work is the study of the Pseudorange error of the GIOVE satellites. To achieve this goal, the specifications defined in Giove A-B Navigation Signal in Space Interface Control Document (ICD) are used to develop a suitable software tool in MATLAB® environment. The tool is able to compute GIOVE A and GIOVE B position from the broadcast ephemerides, to calculate the Pseudorange error and to process it. From the known receiver position and the computed satellite coordinates, the geometric range is obtained and compared with the Pseudorange Measurement, in order to obtain the Pseudorange error.
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A stochastic sigma model for GLONASS satellite Pseudorange
Applied Geomatics, 2011Co-Authors: Salvatore Gaglione, Antonio Angrisano, Giovanni Pugliano, Umberto Robustelli, Raffaele Santamaria, Mario VultaggioAbstract:The GLONASS (Global Navigation Satellite System) is a satellite positioning system able to provide various numbers of air, marine, and any other type of users with all-weather three-dimensional positioning, velocity measuring, and timing anywhere in the world or near-earth space. As known, a GLONASS receiver performs passive Measurements of Pseudoranges and Pseudorange rate of at least four GLONASS satellites as well as receives and processes navigation messages contained within navigation signals of the satellites. The navigation message supplies the satellites' position both in space and in time. Combined processing of the Measurements and the navigation messages of the four (three) GLONASS satellites allows users to determine three (two) position coordinates, three (two) velocity vector constituents, and to refer user time scale to the national reference time UTC (SU). The purpose of this work was to define a stochastic model for Pseudorange variances of GLONASS satellites able to provide its estimation. This evaluation is made for all satellites as a function of the elevation, independently of the user position, starting from real data. To achieve this goal, a suitable software tool MATLAB® is developed. The tool is able to create a GLONASS sky from the broadcast ephemeris, to compute the Pseudorange error and to process it. The used data are extracted from observation and navigation RINEX files (containing both GPS and GLONASS measures). From the known receiver position and the computed satellite coordinates, the geometric range is obtained and compared with the Pseudorange Measurement, in order to achieve the Pseudorange variance and build the model. In order to validate the sigma stationary stochastic model, the results are compared with further data obtained from different stations. The purpose of this work was the creation of an σ model particularly adapted in application as personal navigation device, characterized by the need of a real-time positioning and by a low computational power. The accuracy in real-time positioning can be improved, using a weighted least square (WLS) method for GNSS (GPS, GLONASS, and in the future GALILEO or other feasible systems) Measurements. For GPS Measurements, several suitable σ models for the WLS implementation are already in use; for GLONASS (or GLONASS-GPS together), the same is not available. So, there is need of studies about this topic.
Salos Andrés, Carlos Daniel - One of the best experts on this subject based on the ideXlab platform.
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Contrôle d intégrité appliqué à la réception des signaux GNSS en environnement urbain
INP Toulouse Toulouse, 2013Co-Authors: Salos Andrés, Carlos Daniel, Macabiau Christophe, Martineau AnaïsAbstract:L intégrité des signaux GNSS est définie comme la mesure de la confiance qui peut être placée dans l exactitude des informations fournies par le système de navigation. Bien que le concept d intégrité GNSS a été initialement développé dans le cadre de l aviation civile comme une des exigences standardisées par l Organisation de l Aviation Civile Internationale (OACI) pour l utilisation du GNSS dans les systèmes de Communication, Navigation, et Surveillance / Contrôle du Trafic Aérien (CNS/ATM), un large éventail d applications non aéronautiques ont également besoin de navigation par satellite fiable avec un niveau d intégrité garanti. Beaucoup de ces applications se situent en environnement urbain. Le contrôle d intégrité GNSS est un élément clé des applications de sécurité de la vie (SoL), telle que l aviation, et des applications exigeant une fiabilité critique comme le télépéage basé sur l utilisation du GNSS, pour lesquels des erreurs de positionnement peuvent avoir des conséquences juridiques ou économiques. Chacune de ces applications a ses propres exigences et contraintes, de sorte que la technique de contrôle d intégrité la plus appropriée varie d une application à l autre. Cette thèse traite des systèmes de télépéage utilisant GNSS en environnement urbain. Les systèmes de navigation par satellite sont l une des technologies que l UE recommande pour le Service Européen de Télépéage Electronique (EETS). Ils sont déjà en cours d adoption: des systèmes de télépéage pour le transport poids lourd utilisant GPS comme technologie principale sont opérationnels en Allemagne et en Slovaquie, et un système similaire est envisagé en France à partir de 2013. À l heure actuelle, le contrôle d intégrité GPS s appuie sur des systèmes d augmentation (GBAS, SBAS, ABAS) conçus pour répondre aux exigences de l OACI pour les opérations aviation civile. C est la raison pour laquelle cette thèse débute par une présentation du concept d intégrité en aviation civile afin de comprendre les performances et contraintes des systèmes hérités. La thèse se poursuit par une analyse approfondie des systèmes de télépéage et de navigation GNSS en milieu urbain qui permets de dériver les techniques de contrôle d intégrité GNSS les plus adaptées. Les algorithmes autonomes de type RAIM ont été choisis en raison de leur souplesse et leur capacité d adaptabilité aux environnements urbains. Par la suite, le modèle de mesure de pseudodistances est élaboré. Ce modèle traduit les imprécisions des modèles de correction des erreurs d horloge et d ephemeride, des retards ionosphériques et troposphériques, ainsi que le bruit thermique récepteur et les erreurs dues aux multitrajets. Les exigences d intégrité GNSS pour l application télépéage sont ensuite dérivées à partir de la relation entre les erreurs de positionnement et leur effets dans la facturation finale. Deux algorithmes RAIM sont alors proposés pour l application péage routier. Le premier est l algorithme basé sur les résidus de la solution des moindres carrés pondérés (RAIM WLSR), largement utilisé dans l aviation civile. Seulement, un des principaux défis de l utilisation des algorithmes RAIM classiques en milieux urbains est un taux élevé d indisponibilité causé par la mauvaise géométrie entre le récepteur et les satellites. C est pour cela que un nouvel algorithme RAIM est proposé. Cet algorithme, basé sur le RAIM WLSR, est conçu de sorte à maximiser l occurrence de fournir un positionnement intègre dans un contexte télépéage. Les performances des deux algorithmes RAIM proposés et des systèmes de télépéage associés sont analysés par simulation dans différents environnements ruraux et urbains. Dans tous les cas, la disponibilité du nouvel RAIM est supérieure à celle du RAIM WLSR.Global Navigation Satellite Systems (GNSS) integrity is defined as a measure of the trust that can be placed in the correctness of the information supplied by the navigation system. Although the concept of GNSS integrity has been originally developed in the civil aviation framework as part of the International Civil Aviation Organization (ICAO) requirements for using GNSS in the Communications, Navigation, and Surveillance / Air Traffic Management (CNS/ATM) system, a wide range of non-aviation applications need reliable GNSS navigation with integrity, many of them in urban environments. GNSS integrity monitoring is a key component in Safety of Life (SoL) applications such as aviation, and in the so-called liability critical applications like GNSS-based electronic toll collection, in which positioning errors may have negative legal or economic consequences. At present, GPS integrity monitoring relies on different augmentation systems (GBAS, SBAS, ABAS) that have been conceived to meet the ICAO requirements in civil aviation operations. For this reason, the use of integrity monitoring techniques and systems inherited from civil aviation in non-aviation applications needs to be analyzed, especially in urban environments, which are frequently more challenging than typical aviation environments. Each application has its own requirements and constraints, so the most suitable integrity monitoring technique varies from one application to another. This work focuses on Electronic Toll Collection (ETC) systems based on GNSS in urban environments. Satellite navigation is one of the technologies the directive 2004/52/EC recommends for the European Electronic Toll Service (EETS), and it is already being adopted: toll systems for freight transport that use GPS as primary technology are operational in Germany and Slovakia, and France envisages to establish a similar system from 2013. This dissertation begins presenting first the concept of integrity in civil aviation in order to understand the objectives and constraints of existing GNSS integrity monitoring systems. A thorough analysis of GNSS-based ETC systems and of GNSS navigation in urban environments is done afterwards with the aim of identifying the most suitable road toll schemes, GNSS receiver configurations and integrity monitoring mechanisms. Receiver autonomous integrity monitoring (RAIM) is chosen among other integrity monitoring systems due to its design flexibility and adaptability to urban environments. A nominal Pseudorange Measurement model suitable for integrity-driven applications in urban environments has been calculated dividing the total Pseudorange error into five independent error sources which can be modelled independently: broadcasted satellite clock corrections and ephemeris errors, ionospheric delay, tropospheric delay, receiver thermal noise (plus interferences) and multipath. In this work the fault model that includes all non-nominal errors consists only of major service failures. Afterwards, the GNSS integrity requirements are derived from the relationship between positioning failures and toll charging errors. Two RAIM algorithms are studied. The first of them is the Weighted Least Squares Residual (WLSR) RAIM, widely used in civil aviation and usually set as the reference against which other RAIM techniques are compared. One of the main challenges of RAIM algorithms in urban environments is the high unavailability rate because of the bad user/satellite geometry. For this reason a new RAIM based on the WLSR is proposed, with the objective of providing a trade-off between the false alarm probability and the RAIM availability in order to maximize the probability that the RAIM declares valid a fault-free position. Finally, simulations have been carried out to study the performance of the different RAIM and ETC systems in rural and urban environments. In all cases, the availability obtained with the novel RAIM improve those of the standard WLSR RAIM.TOULOUSE-INP (315552154) / SudocSudocFranceF
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Integrity monitoring applied to the reception of GNSS signals in urban environments
INPT, 2012Co-Authors: Salos Andrés, Carlos DanielAbstract:L’intégrité des signaux GNSS est définie comme la mesure de la confiance qui peut être placée dans l’exactitude des informations fournies par le système de navigation. Bien que le concept d’intégrité GNSS a été initialement développé dans le cadre de l’aviation civile comme une des exigences standardisées par l’Organisation de l’Aviation Civile Internationale (OACI) pour l’utilisation du GNSS dans les systèmes de Communication, Navigation, et Surveillance / Contrôle du Trafic Aérien (CNS/ATM), un large éventail d’applications non aéronautiques ont également besoin de navigation par satellite fiable avec un niveau d’intégrité garanti. Beaucoup de ces applications se situent en environnement urbain. Le contrôle d’intégrité GNSS est un élément clé des applications de sécurité de la vie (SoL), telle que l’aviation, et des applications exigeant une fiabilité critique comme le télépéage basé sur l’utilisation du GNSS, pour lesquels des erreurs de positionnement peuvent avoir des conséquences juridiques ou économiques. Chacune de ces applications a ses propres exigences et contraintes, de sorte que la technique de contrôle d’intégrité la plus appropriée varie d’une application à l’autre. Cette thèse traite des systèmes de télépéage utilisant GNSS en environnement urbain. Les systèmes de navigation par satellite sont l’une des technologies que l’UE recommande pour le Service Européen de Télépéage Electronique (EETS). Ils sont déjà en cours d’adoption: des systèmes de télépéage pour le transport poids lourd utilisant GPS comme technologie principale sont opérationnels en Allemagne et en Slovaquie, et un système similaire est envisagé en France à partir de 2013. À l’heure actuelle, le contrôle d’intégrité GPS s’appuie sur des systèmes d´augmentation (GBAS, SBAS, ABAS) conçus pour répondre aux exigences de l’OACI pour les opérations aviation civile. C´est la raison pour laquelle cette thèse débute par une présentation du concept d’intégrité en aviation civile afin de comprendre les performances et contraintes des systèmes hérités. La thèse se poursuit par une analyse approfondie des systèmes de télépéage et de navigation GNSS en milieu urbain qui permets de dériver les techniques de contrôle d’intégrité GNSS les plus adaptées. Les algorithmes autonomes de type RAIM ont été choisis en raison de leur souplesse et leur capacité d´adaptabilité aux environnements urbains. Par la suite, le modèle de mesure de pseudodistances est élaboré. Ce modèle traduit les imprécisions des modèles de correction des erreurs d’horloge et d’ephemeride, des retards ionosphériques et troposphériques, ainsi que le bruit thermique récepteur et les erreurs dues aux multitrajets. Les exigences d’intégrité GNSS pour l’application télépéage sont ensuite dérivées à partir de la relation entre les erreurs de positionnement et leur effets dans la facturation finale. Deux algorithmes RAIM sont alors proposés pour l’application péage routier. Le premier est l’algorithme basé sur les résidus de la solution des moindres carrés pondérés (RAIM WLSR), largement utilisé dans l’aviation civile. Seulement, un des principaux défis de l’utilisation des algorithmes RAIM classiques en milieux urbains est un taux élevé d’indisponibilité causé par la mauvaise géométrie entre le récepteur et les satellites. C’est pour cela que un nouvel algorithme RAIM est proposé. Cet algorithme, basé sur le RAIM WLSR, est conçu de sorte à maximiser l’occurrence de fournir un positionnement intègre dans un contexte télépéage. Les performances des deux algorithmes RAIM proposés et des systèmes de télépéage associés sont analysés par simulation dans différents environnements ruraux et urbains. Dans tous les cas, la disponibilité du nouvel RAIM est supérieure à celle du RAIM WLSR. ABSTRACT : Global Navigation Satellite Systems (GNSS) integrity is defined as a measure of the trust that can be placed in the correctness of the information supplied by the navigation system. Although the concept of GNSS integrity has been originally developed in the civil aviation framework as part of the International Civil Aviation Organization (ICAO) requirements for using GNSS in the Communications, Navigation, and Surveillance / Air Traffic Management (CNS/ATM) system, a wide range of non-aviation applications need reliable GNSS navigation with integrity, many of them in urban environments. GNSS integrity monitoring is a key component in Safety of Life (SoL) applications such as aviation, and in the so-called liability critical applications like GNSS-based electronic toll collection, in which positioning errors may have negative legal or economic consequences. At present, GPS integrity monitoring relies on different augmentation systems (GBAS, SBAS, ABAS) that have been conceived to meet the ICAO requirements in civil aviation operations. For this reason, the use of integrity monitoring techniques and systems inherited from civil aviation in non-aviation applications needs to be analyzed, especially in urban environments, which are frequently more challenging than typical aviation environments. Each application has its own requirements and constraints, so the most suitable integrity monitoring technique varies from one application to another. This work focuses on Electronic Toll Collection (ETC) systems based on GNSS in urban environments. Satellite navigation is one of the technologies the directive 2004/52/EC recommends for the European Electronic Toll Service (EETS), and it is already being adopted: toll systems for freight transport that use GPS as primary technology are operational in Germany and Slovakia, and France envisages to establish a similar system from 2013. This dissertation begins presenting first the concept of integrity in civil aviation in order to understand the objectives and constraints of existing GNSS integrity monitoring systems. A thorough analysis of GNSS-based ETC systems and of GNSS navigation in urban environments is done afterwards with the aim of identifying the most suitable road toll schemes, GNSS receiver configurations and integrity monitoring mechanisms. Receiver autonomous integrity monitoring (RAIM) is chosen among other integrity monitoring systems due to its design flexibility and adaptability to urban environments. A nominal Pseudorange Measurement model suitable for integrity-driven applications in urban environments has been calculated dividing the total Pseudorange error into five independent error sources which can be modelled independently: broadcasted satellite clock corrections and ephemeris errors, ionospheric delay, tropospheric delay, receiver thermal noise (plus interferences) and multipath. In this work the fault model that includes all non-nominal errors consists only of major service failures. Afterwards, the GNSS integrity requirements are derived from the relationship between positioning failures and toll charging errors. Two RAIM algorithms are studied. The first of them is the Weighted Least Squares Residual (WLSR) RAIM, widely used in civil aviation and usually set as the reference against which other RAIM techniques are compared. One of the main challenges of RAIM algorithms in urban environments is the high unavailability rate because of the bad user/satellite geometry. For this reason a new RAIM based on the WLSR is proposed, with the objective of providing a trade-off between the false alarm probability and the RAIM availability in order to maximize the probability that the RAIM declares valid a fault-free position. Finally, simulations have been carried out to study the performance of the different RAIM and ETC systems in rural and urban environments. In all cases, the availability obtained with the novel RAIM improve those of the standard WLSR RAIM
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Contrôle d’intégrité appliqué à la réception des signaux GNSS en environnement urbain
2012Co-Authors: Salos Andrés, Carlos DanielAbstract:L’intégrité des signaux GNSS est définie comme la mesure de la confiance qui peut être placée dans l’exactitude des informations fournies par le système de navigation. Bien que le concept d’intégrité GNSS a été initialement développé dans le cadre de l’aviation civile comme une des exigences standardisées par l’Organisation de l’Aviation Civile Internationale (OACI) pour l’utilisation du GNSS dans les systèmes de Communication, Navigation, et Surveillance / Contrôle du Trafic Aérien (CNS/ATM), un large éventail d’applications non aéronautiques ont également besoin de navigation par satellite fiable avec un niveau d’intégrité garanti. Beaucoup de ces applications se situent en environnement urbain. Le contrôle d’intégrité GNSS est un élément clé des applications de sécurité de la vie (SoL), telle que l’aviation, et des applications exigeant une fiabilité critique comme le télépéage basé sur l’utilisation du GNSS, pour lesquels des erreurs de positionnement peuvent avoir des conséquences juridiques ou économiques. Chacune de ces applications a ses propres exigences et contraintes, de sorte que la technique de contrôle d’intégrité la plus appropriée varie d’une application à l’autre. Cette thèse traite des systèmes de télépéage utilisant GNSS en environnement urbain. Les systèmes de navigation par satellite sont l’une des technologies que l’UE recommande pour le Service Européen de Télépéage Electronique (EETS). Ils sont déjà en cours d’adoption: des systèmes de télépéage pour le transport poids lourd utilisant GPS comme technologie principale sont opérationnels en Allemagne et en Slovaquie, et un système similaire est envisagé en France à partir de 2013. À l’heure actuelle, le contrôle d’intégrité GPS s’appuie sur des systèmes d´augmentation (GBAS, SBAS, ABAS) conçus pour répondre aux exigences de l’OACI pour les opérations aviation civile. C´est la raison pour laquelle cette thèse débute par une présentation du concept d’intégrité en aviation civile afin de comprendre les performances et contraintes des systèmes hérités. La thèse se poursuit par une analyse approfondie des systèmes de télépéage et de navigation GNSS en milieu urbain qui permets de dériver les techniques de contrôle d’intégrité GNSS les plus adaptées. Les algorithmes autonomes de type RAIM ont été choisis en raison de leur souplesse et leur capacité d´adaptabilité aux environnements urbains. Par la suite, le modèle de mesure de pseudodistances est élaboré. Ce modèle traduit les imprécisions des modèles de correction des erreurs d’horloge et d’ephemeride, des retards ionosphériques et troposphériques, ainsi que le bruit thermique récepteur et les erreurs dues aux multitrajets. Les exigences d’intégrité GNSS pour l’application télépéage sont ensuite dérivées à partir de la relation entre les erreurs de positionnement et leur effets dans la facturation finale. Deux algorithmes RAIM sont alors proposés pour l’application péage routier. Le premier est l’algorithme basé sur les résidus de la solution des moindres carrés pondérés (RAIM WLSR), largement utilisé dans l’aviation civile. Seulement, un des principaux défis de l’utilisation des algorithmes RAIM classiques en milieux urbains est un taux élevé d’indisponibilité causé par la mauvaise géométrie entre le récepteur et les satellites. C’est pour cela que un nouvel algorithme RAIM est proposé. Cet algorithme, basé sur le RAIM WLSR, est conçu de sorte à maximiser l’occurrence de fournir un positionnement intègre dans un contexte télépéage. Les performances des deux algorithmes RAIM proposés et des systèmes de télépéage associés sont analysés par simulation dans différents environnements ruraux et urbains. Dans tous les cas, la disponibilité du nouvel RAIM est supérieure à celle du RAIM WLSR.Global Navigation Satellite Systems (GNSS) integrity is defined as a measure of the trust that can be placed in the correctness of the information supplied by the navigation system. Although the concept of GNSS integrity has been originally developed in the civil aviation framework as part of the International Civil Aviation Organization (ICAO) requirements for using GNSS in the Communications, Navigation, and Surveillance / Air Traffic Management (CNS/ATM) system, a wide range of non-aviation applications need reliable GNSS navigation with integrity, many of them in urban environments. GNSS integrity monitoring is a key component in Safety of Life (SoL) applications such as aviation, and in the so-called liability critical applications like GNSS-based electronic toll collection, in which positioning errors may have negative legal or economic consequences. At present, GPS integrity monitoring relies on different augmentation systems (GBAS, SBAS, ABAS) that have been conceived to meet the ICAO requirements in civil aviation operations. For this reason, the use of integrity monitoring techniques and systems inherited from civil aviation in non-aviation applications needs to be analyzed, especially in urban environments, which are frequently more challenging than typical aviation environments. Each application has its own requirements and constraints, so the most suitable integrity monitoring technique varies from one application to another. This work focuses on Electronic Toll Collection (ETC) systems based on GNSS in urban environments. Satellite navigation is one of the technologies the directive 2004/52/EC recommends for the European Electronic Toll Service (EETS), and it is already being adopted: toll systems for freight transport that use GPS as primary technology are operational in Germany and Slovakia, and France envisages to establish a similar system from 2013. This dissertation begins presenting first the concept of integrity in civil aviation in order to understand the objectives and constraints of existing GNSS integrity monitoring systems. A thorough analysis of GNSS-based ETC systems and of GNSS navigation in urban environments is done afterwards with the aim of identifying the most suitable road toll schemes, GNSS receiver configurations and integrity monitoring mechanisms. Receiver autonomous integrity monitoring (RAIM) is chosen among other integrity monitoring systems due to its design flexibility and adaptability to urban environments. A nominal Pseudorange Measurement model suitable for integrity-driven applications in urban environments has been calculated dividing the total Pseudorange error into five independent error sources which can be modelled independently: broadcasted satellite clock corrections and ephemeris errors, ionospheric delay, tropospheric delay, receiver thermal noise (plus interferences) and multipath. In this work the fault model that includes all non-nominal errors consists only of major service failures. Afterwards, the GNSS integrity requirements are derived from the relationship between positioning failures and toll charging errors. Two RAIM algorithms are studied. The first of them is the Weighted Least Squares Residual (WLSR) RAIM, widely used in civil aviation and usually set as the reference against which other RAIM techniques are compared. One of the main challenges of RAIM algorithms in urban environments is the high unavailability rate because of the bad user/satellite geometry. For this reason a new RAIM based on the WLSR is proposed, with the objective of providing a trade-off between the false alarm probability and the RAIM availability in order to maximize the probability that the RAIM declares valid a fault-free position. Finally, simulations have been carried out to study the performance of the different RAIM and ETC systems in rural and urban environments. In all cases, the availability obtained with the novel RAIM improve those of the standard WLSR RAIM
Antonio Angrisano - One of the best experts on this subject based on the ideXlab platform.
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A resampling strategy based on bootstrap to reduce the effect of large blunders in GPS absolute positioning
Journal of Geodesy, 2018Co-Authors: Antonio Angrisano, Antonio Maratea, Salvatore GaglioneAbstract:In the absence of obstacles, a GPS device is generally able to provide continuous and accurate estimates of position, while in urban scenarios buildings can generate multipath and echo-only phenomena that severely affect the continuity and the accuracy of the provided estimates. Receiver autonomous integrity monitoring (RAIM) techniques are able to reduce the negative consequences of large blunders in urban scenarios, but require both a good redundancy and a low contamination to be effective. In this paper a resampling strategy based on bootstrap is proposed as an alternative to RAIM, in order to estimate accurately position in case of low redundancy and multiple blunders: starting with the Pseudorange Measurement model, at each epoch the available Measurements are bootstrapped—that is random sampled with replacement—and the generated a posteriori empirical distribution is exploited to derive the final position. Compared to standard bootstrap, in this paper the sampling probabilities are not uniform, but vary according to an indicator of the Measurement quality. The proposed method has been compared with two different RAIM techniques on a data set collected in critical conditions, resulting in a clear improvement on all considered figures of merit.
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GIOVE Satellites Pseudorange Error Assessment
Journal of Navigation, 2011Co-Authors: Antonio Angrisano, Salvatore Gaglione, Umberto Robustelli, Ciro Gioia, Mario VultaggioAbstract:Galileo is a global civil navigation satellite system developed in Europe as an alternative to the GPS controlled by the US Department of Defense and GLONASS controlled by Russian Space Forces. It is scheduled to be operative in 2013 and it will have 30 satellites orbiting on three inclined planes with respect to the equatorial plane at an altitude of about 24 000 km. The aim of this work is the study of the Pseudorange error of the GIOVE satellites. To achieve this goal, the specifications defined in Giove A-B Navigation Signal in Space Interface Control Document (ICD) are used to develop a suitable software tool in MATLAB® environment. The tool is able to compute GIOVE A and GIOVE B position from the broadcast ephemerides, to calculate the Pseudorange error and to process it. From the known receiver position and the computed satellite coordinates, the geometric range is obtained and compared with the Pseudorange Measurement, in order to obtain the Pseudorange error.
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A stochastic sigma model for GLONASS satellite Pseudorange
Applied Geomatics, 2011Co-Authors: Salvatore Gaglione, Antonio Angrisano, Giovanni Pugliano, Umberto Robustelli, Raffaele Santamaria, Mario VultaggioAbstract:The GLONASS (Global Navigation Satellite System) is a satellite positioning system able to provide various numbers of air, marine, and any other type of users with all-weather three-dimensional positioning, velocity measuring, and timing anywhere in the world or near-earth space. As known, a GLONASS receiver performs passive Measurements of Pseudoranges and Pseudorange rate of at least four GLONASS satellites as well as receives and processes navigation messages contained within navigation signals of the satellites. The navigation message supplies the satellites' position both in space and in time. Combined processing of the Measurements and the navigation messages of the four (three) GLONASS satellites allows users to determine three (two) position coordinates, three (two) velocity vector constituents, and to refer user time scale to the national reference time UTC (SU). The purpose of this work was to define a stochastic model for Pseudorange variances of GLONASS satellites able to provide its estimation. This evaluation is made for all satellites as a function of the elevation, independently of the user position, starting from real data. To achieve this goal, a suitable software tool MATLAB® is developed. The tool is able to create a GLONASS sky from the broadcast ephemeris, to compute the Pseudorange error and to process it. The used data are extracted from observation and navigation RINEX files (containing both GPS and GLONASS measures). From the known receiver position and the computed satellite coordinates, the geometric range is obtained and compared with the Pseudorange Measurement, in order to achieve the Pseudorange variance and build the model. In order to validate the sigma stationary stochastic model, the results are compared with further data obtained from different stations. The purpose of this work was the creation of an σ model particularly adapted in application as personal navigation device, characterized by the need of a real-time positioning and by a low computational power. The accuracy in real-time positioning can be improved, using a weighted least square (WLS) method for GNSS (GPS, GLONASS, and in the future GALILEO or other feasible systems) Measurements. For GPS Measurements, several suitable σ models for the WLS implementation are already in use; for GLONASS (or GLONASS-GPS together), the same is not available. So, there is need of studies about this topic.
Shunsuke Kamijo - One of the best experts on this subject based on the ideXlab platform.
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3D building model-based pedestrian positioning method using GPS/GLONASS/QZSS and its reliability calculation
GPS Solutions, 2016Co-Authors: Yanlei Gu, Shunsuke KamijoAbstract:The current low-cost global navigation satellite systems (GNSS) receiver cannot calculate satisfactory positioning results for pedestrian applications in urban areas with dense buildings due to multipath and non-line-of-sight effects. We develop a rectified positioning method using a basic three-dimensional city building model and ray-tracing simulation to mitigate the signal reflection effects. This proposed method is achieved by implementing a particle filter to distribute possible position candidates. The likelihood of each candidate is evaluated based on the similarity between the Pseudorange Measurement and simulated Pseudorange of the candidate. Finally, the expectation of all the candidates is the rectified positioning of the proposed map method. The proposed method will serve as one sensor of an integrated system in the future. For this purpose, we successfully define a positioning accuracy based on the distribution of the candidates and their Pseudorange similarity. The real data are recorded at an urban canyon environment in the Chiyoda district of Tokyo using a commercial grade u-blox GNSS receiver. Both static and dynamic tests were performed. With the aid of GLONASS and QZSS, it is shown that the proposed method can achieve a 4.4-m 1σ positioning error in the tested urban canyon area.
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3d building model based pedestrian positioning method using gps glonass qzss and its reliability calculation
Gps Solutions, 2016Co-Authors: Yanlei Gu, Shunsuke KamijoAbstract:The current low-cost global navigation satellite systems (GNSS) receiver cannot calculate satisfactory positioning results for pedestrian applications in urban areas with dense buildings due to multipath and non-line-of-sight effects. We develop a rectified positioning method using a basic three-dimensional city building model and ray-tracing simulation to mitigate the signal reflection effects. This proposed method is achieved by implementing a particle filter to distribute possible position candidates. The likelihood of each candidate is evaluated based on the similarity between the Pseudorange Measurement and simulated Pseudorange of the candidate. Finally, the expectation of all the candidates is the rectified positioning of the proposed map method. The proposed method will serve as one sensor of an integrated system in the future. For this purpose, we successfully define a positioning accuracy based on the distribution of the candidates and their Pseudorange similarity. The real data are recorded at an urban canyon environment in the Chiyoda district of Tokyo using a commercial grade u-blox GNSS receiver. Both static and dynamic tests were performed. With the aid of GLONASS and QZSS, it is shown that the proposed method can achieve a 4.4-m 1ź positioning error in the tested urban canyon area.
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nlos correction exclusion for gnss Measurement using raim and city building models
Sensors, 2015Co-Authors: Li-ta Hsu, Shunsuke KamijoAbstract:Currently, global navigation satellite system (GNSS) receivers can provide accurate and reliable positioning service in open-field areas. However, their performance in the downtown areas of cities is still affected by the multipath and none-line-of-sight (NLOS) receptions. This paper proposes a new positioning method using 3D building models and the receiver autonomous integrity monitoring (RAIM) satellite selection method to achieve satisfactory positioning performance in urban area. The 3D building model uses a ray-tracing technique to simulate the line-of-sight (LOS) and NLOS signal travel distance, which is well-known as Pseudorange, between the satellite and receiver. The proposed RAIM fault detection and exclusion (FDE) is able to compare the similarity between the raw Pseudorange Measurement and the simulated Pseudorange. The Measurement of the satellite will be excluded if the simulated and raw Pseudoranges are inconsistent. Because of the assumption of the single reflection in the ray-tracing technique, an inconsistent case indicates it is a double or multiple reflected NLOS signal. According to the experimental results, the RAIM satellite selection technique can reduce by about 8.4% and 36.2% the positioning solutions with large errors (solutions estimated on the wrong side of the road) for the 3D building model method in the middle and deep urban canyon environment, respectively.
