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Planification stratégique de trajectoires d'avion 4D sous uncertitudes
No full textTo sustain the continuously increasing air traffic demand, the future air traffic management system will rely on a so-called Trajectory Based Operations (TBO) concept that will increase air traffic capacity by reducing the controllers workload. This will be achieved by transferring tactical conflict detection and resolution tasks to the pre-tactical planning phase. In this future air traffic management paradigm context, this theis presents a methodology to address such pre-tactical trajectory planning at nation-wide and continent scale. The proposed methodology aims at minimizing the global interaction between aircraft trajectories by allocating alternative departure times, alternative horizontal flight paths, and alternative flight levels to the trajectories involved in the interaction. To improve robustness of the pre-tactical trajectory planning, uncertainty of aircraft position and aircraft arrival time to any given position on the trajectory are considered. In addition, the thesis addresses also the problem of planning of military mission in the civilian traffic in order to reduce the associated inpact.Pour soutenir la demande de trafic aérien en constante augmentation, le futur système de gestion du trafic aérien s'appuiera sur un concept basé sur les trajectoire (TBO) qui augmentera la capacité du trafic aérien en réduisant la charge de travail des contrôleurs. Cet objectif sera atteint en transférant les tâches tactiques de détection et de résolution des conflits à la phase de planification pré-tactique. Dans ce futur contexte de gestion du trafic aérien, cette thèse présente une méthodologie permettant de planifier le traffic pré-tactique à l'échelle nationale et continentale. La méthodologie proposée vise à minimiser l'interaction globale entre les trajectoires des aéronefs en allouant des heures de départ alternatives, des profiles de vol horizontales et des niveaux de vol alternatifs aux avions impliquées dans l'interaction. Pour améliorer la robustesse de la planification de trajectoire pré-tactique, l'incertitude de la position et de l'heure d'arrivée de l'aéronef à une position donnée sur la trajectoire est prise en compte. En outre, la thèse aborde également le problème de la planification de la mission militaire dans le trafic civil afin de réduire l'impact associé
Using the 3-D Vector Antenna as the Short-Range Direction-Finding Sensor: Primary Theory and Experimental Proof
No full textInternational audienceThis letter showcases the design, implementation, and verification of a vector antenna (VA) capable of direction finding. By adopting the tapered slot (also known as Vivaldi) element as the constitutive VA element and a four-season layout, the VA in this work can identify the radio source in a wide spectrum range in the 3-D space. Practical issues, such as steering vector calibration, exploitation of polarization, and angle estimation with partial electromagnetic measurements, are addressed to ensure the functionality of the proposed VA in practice. A four-channel phase-locked software-defined radio platform and quasi-real-time angle estimation algorithms are designed and implemented to verify the direction-finding (DF) capability of the VA for directly propagated, reflected, and diffracted radio signals. The results of the experiment prove the effectiveness of the theory and our practical VA measures for 3-D direction finding under various conditions and potentially inspire localization, mapping, and navigation in short-range scenarios
Assessing Distributed Consensus Performance on Mobile Cyber-Physical System Swarms
No full textInternational audienceMobile Cyber-Physical System (CPS) Swarms are likely to change our daily lives significantly in several application domains, including smart cities, space exploration, environmental monitoring, and transporting systems. Yet, industrial projects fundamentally rely on centralized communication infrastructures which in turn lead to suboptimal performance and limited autonomy for both sensing and actuating. To enhance communication and distributed coordination within the swarm, reliable distributed computing through consensus protocols constitutes a promising approach. Nonetheless, only a handful of studies has considered evaluating reliable distributed computing in Mobile CPS Swarms. The goal of this work is to evaluate the performance of consensus protocols on CPS swarms with processing units deployed on mobile nodes. Running on top of an emulation framework for mobile CPS, our preliminary evaluation focuses on evaluating three key deployment aspects of Mobile CPS Swarms executing a consensus protocol: the effective cost of mobility; the impact of the connectivity of nodes and the eventual network partitions; and the price of continuous routing updates in the mobile environment. Our experimental results indicate the transient network partition in mobile environments are common. They also suggest that the sparsity of dynamic communication network and continuous routing updates have a major impact on the performance of distributed consensus protocols
Design of Micro-drone Autopilot Architecture with Static Scheduling Optimization
No full textInternational audienceThis paper presents the internal architecture of a Modifiable Off-the-Shelf (MOTS) open-source autopilot. The analysis of a set of functional and hardware requirements reveals that the core of the autopilot can be implemented as a single-threaded system, with a main loop acting as a non-preemptive static scheduler, provided that the internal structure is well-organized. We discuss how the type of bus used for sensor communication influences the nature of the events received from the sensors, whether they are solicited or unsolicited. We demonstrate that, depending on the workload that a main loop iteration must handle, the execution time of a single iteration can exceed the defined period, potentially causing delays in attitude correction. Finally, we explore the degrees of freedom available to mitigate the impact of such overloads by smoothing out the periodic workload
Régression géodésique dans SE(3) : application à l'estimation de la position d'un mobile
No full textInternational audienceDans cette communication, nous nous intéressons au problème d'estimation de la position d'un mobile tel qu'un drone à partir de positions mesurées bruitées en utilisant le paradigme des groupes de Lie. Pour modéliser le mouvement d'un solide rigide, le groupe de Lie approprié est le groupe Spécial Euclidien SE(n), avec n = 2 ou 3 selon le problème posé. Notre travail se situe dans un cadre paramétrique tel que développé par Hinkle et al. (2014), qui ont établi des équations pour la régression géodésique, voire polynomiale sur des variétés Riemanniennes. Notre but est d'implémenter cette technique sur le groupe de Lie SE(3). Etant donné un ensemble de points de SE(3) représentant des mesures de la trajectoire d'un mobile, on souhaite trouver la géodésique qui s'ajuste le mieux à ces points au sens des moindres carrés Riemanniens. Ensuite, nous proposons des applications sur des données simulées pour illustrer ce travail. Enfin, nous discutons des limites de cette méthode et des perspectives futures à donner
Leveraging passengers' mobile network data for an integrated air-rail frequency planning in Spain
No full textInternational audienceThis study addresses the integrated air-rail frequency planning problem with the goal of estimating jointly flight and long-distance train frequencies while considering potential synchronisation between the two modes and passenger preferences. It introduces a generalised cost model to capture passenger travel preferences and incorporates CO2 emissions modelling to minimise the environmental impact. The model is tested on the Spanish air-rail transportation network using real passenger demand from mobile phone data. The results indicate that integrating air and rail frequency planning, along with considering environmental costs, can reduce CO2 emissions by over 66%, thanks to the air-to-rail transfer, with only a 20minute increase in average door-to-door travel time
Graphlet correlation distance to compare small graphs
No full textInternational audienceGraph models are standard for representing mutual relationships between sets of entities. Often, graphs deal with a large number of entities with a small number of connections (e.g. social media relationships, infectious disease spread). The distances or similarities between such large graphs are known to be well established by the Graphlet Correlation Distance (GCD). This paper deals with small graphs (with potentially high densities of connections) that have been somewhat neglected in the literature but that concern important fora like sociology, ecology and fisheries, to mention some examples. First, based on numerical experiments, we study the conditions under which Erdős-Rényi, Fitness Scale-Free, Watts-Strogatz small-world and geometric graphs can be distinguished by a specific GCD measure based on 11 orbits, the GCD11. This is done with respect to the density and the order (i.e. the number of nodes) of the graphs when comparing graphs with the same and different orders. Second, we develop a randomization statistical test based on the GCD11 to compare empirical graphs to the four possible null models used in this analysis and apply it to a fishing case study where graphs represent pairwise proximity between fishing vessels. The statistical test rules out independent pairing within the fleet studied which is a standard assumption in fisheries. It also illustrates the difficulty to identify similarities between real-world small graphs and graph models
General Extremal Field Method for Time-Optimal Trajectory Planning in Flow Fields
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Modeling technology changes in air transport in the presence of a market shock: A passenger-based analysis
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Positionnement précis coopératif de mobiles low-cost en milieu urbain
No full textIn recent years, our society has been preparing for a paradigm shift toward the hyper-connectivity of urban areas. This highly anticipated rise of connected smart city centers is led by the development of low-cost connected smartphone devices owned by each one of us. In this context, the demand for low-cost, high-precision localization solutions is driven by the development of novel autonomous systems. After Googe announced the release of Android GNSS raw data measurements on mobile devices, the enthusiasm around those low-cost positioning devices quickly grew in the scientific community. The increasing need of Location Based Services (LBS) provoked the rapid evolution of smartphones embedded low-cost Global Navigation Satellite System (GNSS) chipsets within the last few years. Most Android devices are now equipped with multi-constellation and multi-frequency positioning chipset. However, various drawbacks prevent the realization of above-mentioned techniques on hand-held mobiles. Smartphones positioning capabilities are limited by the tight-integration of hardware components within the device. Integrated low-cost components, such as the linearly polarized antenna, are unoptimized for acquiring multi-frequency GNSS signals and their operation in a constrained environment quickly becomes a challenge for mitigating disruptive multipath events. Moreover, due to a fierce technological competition between chipset manufacturers, embedded GNSS receivers have been conceived to act as "black-box" processes. The receiver parameterization is kept confidential and only GNSS raw data measurements are outputted to the user. In order to overcome those difficulties, this research work aims to develop a collaborative network positioning system between smartphones. The implementation of a cooperative smartphone network takes advantage of the tremendous number of connected Android devices present in today's city centers for refining and improving users position accuracy and integrity in urban environments. This research thesis presents a thorough analysis of Android GNSS raw data measurements aiming at lifting the ambiguity generated by receivers' "black-box" processes on a wide variety of Android smartphone brands and models. A wide data collection campaign, on 7 different smartphone models in real-life urban conditions, has been conducted for assessing the positioning performance of those contemporary low-cost devices. After grasping the receivers' mechanisms, the implementation of Android GNSS raw data measurements in collaborative positioning algorithms has been investigated. An innovative smartphone-based double code difference method has been employed to compute the inter-phone distance between network's users, named Inter-Phone Ranging (IPR). This technique was tested for nominal and urban scenario cases and has demonstrated its reliability for collaborative positioning implementation. Finally, a smartphone-based cooperative engine, called SmartCoop, was developed and evaluated. This collaborative estimation technique exploits the previously computed IPR ranges in a non-linear constrained optimization problem. An experimental protocol has been put in place in order to determine the estimation method efficiency through a series of simulation runs for both nominal and urban scenarios. The presented results analysis supports our hypothesis that smartphone-based collaborative engines enhance Android positioning performance in urban canyon.Ces dernières années, l’usage fait de notre téléphone mobile évolue. En effet, grâce au développement technologique ainsi qu’à l’hyperconnectivité de nos activées quotidiennes, ces appareils connectés ont pris une place centrale dans notre société. Après l’annonce faite par Google, concernant la mise en service d’une mise à jour Android permettant de récupérer les mesures GNSS brutes, les smartphones sont rapidement devenus attrayant pour la communauté scientifique, en tant que récepteur GNSS bas-coût grand public. Les premières études menées sur ces appareils consistaient à transposer les algorithmes GNSS avancés (RTK et PPP) sur ces périphériques.Cependant, l’implémentation de ces techniques se heurte à la faible qualité des données de positionnement mobiles. En effet, en raison d’une architecture restreinte et de composants auxiliaires bas-coût, la performance du positionnement sur mobile est rapidement impactée par différents biais d’erreur. Ce phénomène s’accentue en milieu urbain, notamment à cause de l’antenne interne du téléphone dont les spécifications sont inadaptées au traitement de signaux multifréquences et au positionnement en environnement contraint. De plus, les paramètres et réglages de ces récepteurs embarqués sont tenus secret par les constructeurs et seules les données GNSS brutes sont fournies à l’utilisateur, rendant leur utilisation ambiguë.Afin de surmonter ces difficultés, ce projet de recherche ambitionne le développement d’un algorithme collaboratif dédié aux smartphones. La création de ce réseau coopératif permettrait de tirer avantage du nombre croissant de téléphones mobiles connectés agglomérés dans les rues des grands centres-villes. Cette thèse présente une analyse complète et détaillée des mesures Android GNSS brutes afin de lever l’ambiguïté créée par les procédés de « boîte-noire » employés par les récepteurs embarqués. Une grande campagne de collecte de données fut organisée pour évaluer la performance du positionnement sur téléphone en milieu urbain. Cette campagne a été réalisée sur 7 smartphones en conditions réelles. À la suite de cette étude, une méthode de caractérisation des données GNSS brutes fut créée afin de couvrir le spectre de la plupart des modèles de téléphone mobile Android.Après avoir analysé les mécanismes de positionnement interne aux smartphones, un algorithme collaboratif a été implémenté utilisant les données GNSS d’Android. Une méthode de double différence sur les mesures de code a été proposée afin de permettre l’estimation des distances entre utilisateurs d’un réseau coopératif. Cette technique innovante a été baptisée « Inter-Phone Ranging » (IPR). La fiabilité et la précision de cette méthode d’estimation sont démontrées par plusieurs études couvrant plusieurs environnements. Enfin, après avoir méthodiquement caractérisé la mise en place d’un réseau collaboratif de téléphones mobiles, un algorithme de positionnement collaboratif appelé « SmartCoop » est présenté. Ce dispositif permet d’exploiter les mesures d’inter-distances entre utilisateurs du réseau afin de résoudre un problème d’optimisation à contraintes non-linéaires. Cette méthode d’estimation a pour but d’améliorer la précision et la dispersion de la position de tous les utilisateurs du réseau. Ce système coopératif a été validé en simulation. L’analyse des résultats obtenus nous permet de penser que cet algorithme coopératif innovant participe à l’amélioration globale de la performance du positionnement sur téléphone mobile en milieu urbain