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Holistic Approach for Aircraft Trajectory Optimization Using Optimal Control
No full textInternational audienceThis paper deals with an optimal control approach for commercial aircraft trajectory planning, focusing on the vertical path and the minimization of the fuel burned. The main contribution is the optimization of the whole trajectory, also called the mission, without prior separation into different flight phases (climb, cruise, and descent), contrary to traditional approaches that consider the flight phases sequentially. The proposed optimal control problem (OCP) is formulated and then solved using a direct collocation method. Initial results yield optimal trajectories with a gradual climb during the cruise (climb cruise), which correspond to theoretical trajectories that minimize fuel consumption. Furthermore, a penalization is introduced to ensure vertical profiles featuring horizontal cruise levels on so-called flight levels, compliant with current air traffic management regulations. The use of direct methods to address this OCP induces large nonlinear optimization problems that are solved using an interior point method. This methodology is likely to lead to poor local optima, but a simple multistart heuristic shows that the solutions found for standard problems appear to be globally optimal. Such an approach does not need to impose a priori the cruise flight levels and is suitable for commercial aircraft flight planning purposes. It leads to fuel saving and subsequently to important improvements against environmental impact by reducing CO2 emissions
Assessment of Number of Critical Satellites for Ground-Based Augmentation System Continuity Allocation to Support Category II/III Precision Approaches
No full textInternational audienceThe ground-based augmentation system (GBAS) is a regional system supporting navigation and ensuring the integrity of aircraft near airports during precision approaches. Standardized at the international level, GBAS Approach Service Types (GASTs) C and D, which are defined for the GPS L1 signal, support CAT I and II/III precision approaches with decision heights of 200 and 50 ft, respectively. However, the future GBAS, GAST E, which utilizes dual-frequency and multi-constellation signals, and the GAST D1, defined for both GPS L1 and Galileo E1 signals, require the establishment of standards. To define the continuity requirement, the number of critical satellites must be considered. Currently, there is a lack of analysis on the number of critical satellites for various GBAS service types available to the public. This paper aims to evaluate the number of critical satellites for future GBAS service types, employing optimized GPS and Galileo constellations and assessing all potential protection levels worldwide. The methodology to model the difference of position solutions using the 30 s and 100 s smoothing filters is presented in detail to compute the protection level for GASTs D and D1. The resulting number of critical satellites can be used to define the continuity allocation of future GBAS
Etude et caractérisation de la fatigue mentale et de la flexibilité cognitive dans le contexte des opérations drone longue endurance
No full textInternational audienceL'opération de drones, que ce soit dans des contextes militaires ou civils, devient plus commune. Les phases d'opérations dépassent fréquemment les 24h. En conséquence, la fatigue mentale des opérateurs peut entraîner des erreurs qui posent de sérieux problèmes de sécurité. La détection en ligne d'états mentaux dégradés grâce à des interfaces cerveaux-machines est une solution potentielle à ce problème. Ces systèmes permettraient l'adaptation des interfaces de pilotage de drones afin de prendre en compte ces états par le biais de mesures complémentaires de performance et d'état physiologique. L'adaptativité des interfaces de pilotage pourrait être optimisée pour augmenter la flexibilité cognitive, facilitant le changement de tâches de pilotage
3D‐printed heterogeneous isotropic–anisotropic dielectric resonator for singly fed dual‐band circularly polarised antennas
No full textInternational audienceAbstract The design of three‐dimensional (3D)‐printed heterogeneous ceramics exhibiting isotropic and anisotropic dielectric permittivities at microwave frequencies is studied for dielectric resonator antenna (DRA) applications. The heterogeneous ceramics are engineered by using periodic structures made up of subwavelength unit cells filled with zirconia ceramic and air. Ceramic stereolithography (CSLA) allows the 3D printing of a one‐piece ceramic block mixing isotropic and anisotropic dielectric regions. In order to demonstrate the possibility of exploiting such 3D‐printed ceramics, a singly fed dual‐band circularly polarised DRA is presented. To achieve circular polarisation at both bands, the relative permittivity of the dielectric resonator is locally controlled by introducing anisotropic dielectric regions. The 3D‐printed DRA is finally measured, and its results agree well with the simulations
Fast Marching Tree applied to geodesic trajectories in presence of uncertain wind: a day of flights in Europe study
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LRP-GUS: A Visual Based Data Reduction Algorithm for Neural Networks
No full textInternational audienceDeriving general rules to estimate a neural network samplecomplexity is a difficult problem. Therefore, in practice, datasets areoften large to ensure sufficient class samples representation. This comesat the cost of high power consumption and long training time. This paperintroduces a novel data reduction method for Deep Learning classifiers,called LRP-GUS, focusing on visual features. The idea behind LRPGUS is to reduce the size of our training dataset by exploiting visualfeatures and their relevance. The proposed technique is tested on theMNIST and Fashion-MNIST datasets. We evaluate the method usingcompression rates, accuracy and F1 scores per class. For instance, ourmethod achieves compression rates of 96.10% for MNIST and 75.94%for Fashion-MNIST, at the cost of a drop of 3% test accuracy for bothdatasets
Évaluation de la dynamique en boucle fermée dans le cadre de la conception et l'optimisation multidisciplinaire de petits drones
No full textInternational audienceThere has been an increasing interest in the application of agile unmanned aerial vehicles (UAVs) for various missions. In this paper, we present an introductory assessment of the impact of addressing control feasibility in the Multidisciplinary Design and Optimization (MDO) of such vehicles. Our approach involves incorporating dynamical simulation disciplines into an existing MDO process, originally formulated for tail-sitter vehicles, to achieve more dexterous flights. Specifically, we simulate the cruise phase of an UAV flight by coupling a flight dynamics module with a control system that includes attitude and velocity control as well as a guidance law for 3D navigation. An open loop simulation is also employed to account for the vehicle's ability to hover. We begin our studies with a single design variable optimization problem and demonstrate how the simulation can be used to reduce energy consumption. Final results, obtained optimizing the vehicle and guidance law gains, highlight the effectiveness of this approach in improving the control maneuverability and energy efficiency of an agile UAV
Linear Contrails Detection, Tracking and Matching with Aircraft Using Geostationary Satellite and Air Traffic Data
No full textInternational audienceClimate impact models of the non-CO 2 emissions of aviation are still subject to significant uncertainties. Condensation trails, or contrails, are one of these non-CO 2 effects. In order to validate the contrail simulation models, a dataset of observations covering the entire lifetime of the contrails will be required, as well as the characteristics of the aircraft which produced them. This study carries on the work on contrail observation from geostationary satellite by proposing a new way to track contrails and identify the flight that produced it using geostationary satellite infrared images, weather data as well as air traffic data. It solves the tracking and the identification problem as one, each process leveraging information from the other to achieve a better overall result. This study is a new step towards a consistent contrail dataset that could be used to validate contrail models
