Multipath study on the airport surface

International audienceAirport Navigation will require more stringent localization performance requirements than in-flight navigation [1]. GNSS signals (Global Navigation Satellites Systems) can be envisaged to elaborate the aircraft estimate position on the airport surface. To improve the performance of localization on the airport, the errors on GNSS signals particular to the airport environment must be characterized. Most of these errors are well known such as ionosphere error, troposphere error, etc, and do not depend on the airport environment. But to achieve the expected sub-metric performance, it is necessary to better model multipath error for which a model already exists but is valid for operations from en-route down to CAT I only. In this paper, an analysis of real GPS measurements (using code pseudo range measurement, carrier phase measurement, Doppler measurement and the estimate C/N0 ratio measurement) during taxiing operation on the airport surface is conducted. The goal of this paper is to evaluate when multipath occurs and to compare the multipath model (elaborated from the standard deviation of the measurement errors due to multipath) based on those collected measurements in the airport with different models proposed in the literature (not necessary proposed for airport navigation)

Review and classification of vision-based localisation techniques in unknown environments

International audienceThis study presents a review of the state-of-the-art and a novel classification of current vision-based localisation techniques in unknown environments. Indeed, because of progresses made in computer vision, it is now possible to consider vision-based systems as promising navigation means that can complement traditional navigation sensors like global navigation satellite systems (GNSSs) and inertial navigation systems. This study aims to review techniques employing a camera as a localisation sensor, provide a classification of techniques and introduce schemes that exploit the use of video information within a multi-sensor system. In fact, a general model is needed to better compare existing techniques in order to decide which approach is appropriate and which are the innovation axes. In addition, existing classifications only consider techniques based on vision as a standalone tool and do not consider video as a sensor among others. The focus is addressed to scenarios where no a priori knowledge of the environment is provided. In fact, these scenarios are the most challenging since the system has to cope with objects as they appear in the scene without any prior information about their expected position

Study of the contribution of GNSS/INS hybridization to GNSS integrity monitoring for civil aviation applications

Le futur système de navigation par satellites GNSS devra satisfaire les exigences définies par l'OACI en termes de précision, d'intégrité, de disponibilité et de continuité de service. Le GPS ne permet pas de satisfaire pleinement ces exigences de manière autonome. En revanche son hybridation avec les systèmes de navigation inertielle tels que l'IRS est une solution candidate. Les mesures GPS sont utilisées comme observation pour l'estimation des erreurs inertielles, les données IRS corrigées forment la solution de navigation utilisée pour le positionnement. Lors de l'indisponibilité du signal GPS, l'IRS calibrée peut assurer la continuité de la navigation avec une bonne précision. Toutefois, de nombreuses perturbations peuvent affecter le signal reçu par le récepteur GPS et conduire à une mauvaise re-calibration de l'IRS. Les interférences sont les perturbations les plus redoutées par l'aviation civile: elles peuvent affecter au même instant plusieurs canaux de poursuite du signal. Cette étude débute par une caractérisation des systèmes GPS et IRS, ainsi que de leur hybridation serrée. Deux logiciels de génération des mesures GPS et IRS, et un logiciel d'intégration par filtrage de Kalman ont été réalisés et validés. Trois algorithmes de contrôle d'intégrité du signal GPS sont ensuite analysés. Un algorithme basé seulement sur la redondance des satellites poursuivis, de type RAIM instantané, a été implanté et ses performances en terme de disponibilité ont été caractérisées. Deux algorithmes AAIM classiques qui prennent en compte l'information inertielle et offrent de meilleures performances que le RAIM sont présentés. Ils sont construits sur l'hypothèse d'une défaillance de mesure unique. Nous avons choisi de développer l'étude de l'algorithme dit du maximum de séparation appliqué à l'hybridation GPS/IRS et développé par Honeywell. Par la suite, nous nous sommes intéressés à son adaptation dans le cas où plusieurs mesures GNSS peuvent être affectées instantanément.TOULOUSE-ENSEEIHT (315552331) / SudocSudocFranceF

A Low-cost GNSS/IMU/Visual monoSLAM/WSS Integration Based on Federated Kalman Filtering for Navigation in Urban Environments

International audienceCar navigation performance improvement is a subject of great interest nowadays especially with the development of autonomous car navigation. In urban environments, it is often difficult to rely on standalone Global Navigation Satellite System (GNSS) to obtain continuously an accurate and reliable navigation solution. In fact, the presence of buildings and other structures hindering the reception of GNSS signals (blockage, multipath, NLOS, poor geometry, etc.) makes it difficult for GNSS to provide accurate, continuous and reliable navigation solution in such an environment. A possible solution for this problem is to fuse information from a limited number of GNSS measurements and other sensors in order to enhance the system performance in terms of accuracy and availability. In this paper, we propose an integrated navigation system that fuses different sensor information in order to improve the car navigation performance in urban environments. A Low-cost navigation solution is proposed since the intended application is cost-sensitive. The proposed solution integrates information from an Inertial Measurement Unit (IMU), a GNSS receiver, a Wheel Speed Sensor (WSS) and a vision module based on monocular Simultaneous Localization And Mapping (SLAM). Motion constraints related to the movement of a land vehicle on the ground are also taken into account

State of the art in airport navigation

10 pagesInternational audienceThe general increase in air traffic and the complexity of modern airport layouts have conducted to think about new technologies to assist pilots during maneuvers on airport surface. Some airport navigation applications have been developed in recent years. The current technologies plot the estimated aircraft position on the airport map. In good visibility condition, this information helps the pilot to navigate on the airport. These applications contribute to the reduction of the taxiing time and runway incursions. Nevertheless, this information is not sufficient to navigate in low visibility condition. This paper introduces the state of the art in airport navigation, with the current functions available to assist pilots, and also the additionalapplications envisaged to improve the airport navigation in low visibility condition. Current constraints and limitations of airport navigation development are highlighted

A Methodology to Elaborate Aircraft Localization Requirements for Airport Navigation

http://www.ion.org/publications/abstract.cfm?articleID=9614 http://telecom.recherche.enac.fr/data/doc.ltst/2011/A%20Methodology%20to%20Elaborate%20Aircraft%20Localization%20Requirements%20for%20Airport%20Navigation.pdfInternational audienceThe general increase in air traffic and the complexity of modern airport layouts have led to think about new system opportunities to assist pilots during maneuvers on airport surface. Two applications will be considered in this paper: guidance and control. Guidance application provides indication to the pilot to navigate on the airport surface whereas control application provides steering indications. These two applications will allow the pilot to drive under low visibility conditions. This assistance is based on the knowledge of the aircraft position on the airport surface. However, precise requirements on aircraft localization service on the airport surface, in terms of accuracy, integrity, continuity and availability, have not been completely expressed by existing standards. This paper proposes a methodology to derive these requirements based on FHA (Functional Hazard Analysis) method. FHA is a predictive technique whose goal is to explore the functional effects of failures on parts of the system. It results in the suggestion of 95% accuracy, integrity risk, HAL (Horizontal Alert Limit) and TTA (Time To Alert) requirements according to the visibility conditions for the different operations

RAIM performance in presence of multiple range failures

International audienceIt is currently stated and widely accepted by industry and users that the RAIM is designed to provide timely warnings in the situation where only one of the range measurements used at the current epoch is affected by an unacceptable bias. However, given the range of potential applications of RAIM in the future, in particular with the advent of Galileo and the generalization of Safety of Life applications, which should spread from the civil aviation community to many other professional sectors, it is very important to better understand the fundamental properties of RAIM, and in particular the potential of RAIM to detect multiple failures on range measurements. The purpose of the study presented in this paper is to analyze the performance of a RAIM in the presence of multiple simultaneous range errors. In particular, we conduct a theoretical analysis to determine in which cases the Least Squares Residuals RAIM detection criterion is not affected, and analyzed results of Monte-Carlo simulations in presence of up to four range failures. The theoretical analysis outlined above aims at determining in what conditions the Least Squares Residuals RAIM detection criterion remains unaffected by multiple range failures, searching for what we call criterion unaffecting range errors. We show that, provided the satellite constellation does not have any degenerated geometrical properties, the dimension of the vector sub-space of these criterion unaffecting errors is max(4-(N-p),0), where N is the number of tracked satellites and p is the number of faulty pseudorange measurements. The immediate conclusion is that if N-4 pseudo range measurements are affected, or less than that, by a large error, there exists no error that will not affect the RAIM detection criterion, and globally due to the negligible probability that unintentional interference lies in a small dimension sub-space, the RAIM detection criterion exhibits a natural detection capability even if up to N-2 pseudo-range measurements are faulty. This theoretical result defines the properties of the errors that lead to zero change in the detection criterion. To jump to a more operational conclusion, it remains to know what the possibility is for multiple range errors to induce a detection criterion that is below the detection threshold. So to complement the theoretical analysis outlined above, we ran Monte Carlo simulations inserting up to four range failures and analyzing the detection capacity. The capacity of RAIM detection is also analyzed in the presence of intentional jamming

Antalgie dans les services médico-chirurgicaux adultes. Recommandations pratiques du réseau douleur des Hôpitaux Universitaires de Genève

Guidelines for pain management in the medical and surgical departments of the Geneva University Hospitals (GUH) have been systematically developed using a multidisciplinary approach. These guidelines are aimed towards improving healthcare quality. We point to the ways the pain network of the GUH has elected to deal with the ever-increasing progression of concepts regarding pain management. This is of importance at a time when the risks related to the patients' transitions between the different departments, to the specificities of the clinical practices, and to the need for personalized care have never been so high