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Air Traffic Complexity Map Based on Linear Dynamical Systems
No full textInternational audienceThis paper presents a new air traffic complexity metric based on linear dynamical systems, of which the goal is to quantify the intrinsic complexity of a set of aircraft trajectories. Previous works have shown that the structure and organization of air traffic are essential factors in the perception of the complexity of an air traffic situation. Usually they were not able to explicitly address trajectory pattern organization. The new metric, by identifying the organization properties of trajectories in a traffic pattern, captures some of the key factors involved in ATC complexity. The key idea of this work is to find a linear dynamical system which fits a vector field as closely as possible to the observations given by the aircraft positions and speeds. This approach produces an aggregate complexity metric that enables to identify high (low) complexity regions of airspace and compare their relative complexity. The metric is very appropriate to compare different traffic situations for any scale (sector or country) by associatting a complexity index to each trajectory sample in the airspace. For instance, to compute the complexity for a sector, one must just sum-up complexity for trajectory samples intersecting such a sector. This computation can also be extended in the time dimension in order to estimate the average complexity in a given airspace for a period of time
Optimal Path Planning for Soaring Flight
No full textInternational audienceIn the last couple of years, performances of light soaring aircraft (para gliders, hang glider or light sailplane) have increased significantly, allowing pilots to fly great distances using only the convective energy of the atmosphere. This activity, called "Cross-Country flying", requires topological and aerological knowledge and a lot of pre-flight preparation in order to make the right decisions, and thus maximize the flying distance or minimize the flying time in a race. To optimize these flights, a pre-tactical decision support tool has been developed. This tool results from the adaptation of a sampling-based algorithm (FMT*). It is extended in such a way it can deal with differential constraints associated with light soaring aircraft, operating in a convective atmosphere, in a field of wind and close to reliefs. The method has been validated on real light soaring aircraft trajectories
Design of experiments for mixed continuous and discrete variables
No full textDesign of experiments (DoE) are used in various contexts such as optimization or uncertainty quantification when relying on a time-consuming numerical simulator. It aims to select a limited number of points at which evaluating the simulator provides maximal knowledge on the simulator outputs of interest. One motivating application is the optimal design of turbine blades in an helicopter engine, which takes as inputs mixed continuous and binary variables. This paper proposes two new approaches for space-filling design over the mixed continuous and discrete space. Numerical results for three different types of DoE problems (mixed integers, mixed binaries with cyclic symmetry, and time series) are presented. The obtained results illustrate the good performance of the proposed methods and the wide range of applications they can address
Anomaly Detection for ICS Based on Deep Learning: A Use Case for Aeronautical Radar Data
No full textInternational audienceIndustrial Control Systems (ICS) are no longer restricted to industrial production. They are also at the heart of safety-critical systems and carry out key information that require strong need in terms of availability and integrity. Furthermore, they are gradually connected with the Internet. In the context of Air Traffic Management, safety critical data are generally time series which contain periodic events. Anomalies can hardly be detected as we only have a little knowledge of the traffic characteristic and the kind of anomalies we might encounter. Consequently, detecting them is challenging as it requires high detection accuracy currently unfeasible with traditional methods based on anomaly signatures or predictions. To cope with this issue, we introduce an anomaly detection method for ICS based on Long Short Term Memory (LSTM) that outperforms the accuracy of traditional ones. We experiment and develop our method with one major dataset containing French civil radar aviation data. We then evaluate our scheme with different datasets containing ICS monitoring data (publicly available predictable time series data) and show that our autoencoder can detect anomalies from predictable times series and present a higher detection rate on average than traditional detection methods
Performance-based emergency landing trajectory planning applying meta-heuristic and Dubins paths
No full textInternational audienceEmergency Landing is a complex problem of optimal path planning of an impairedairplane in presence of obstacles, while the airplane performance characteristics havedegraded. Some in-flight failures can affect the airplane dynamics and therefore the newdynamic constraints must be considered in flight planning to the desired landing site. Thispaper introduces a novel hybrid form of Dubins-simulated annealing (HDSA) optimization framework for emergency landing. The proposed architecture applies Dubins paths and Apollonius' tangent line to generate candidate pieces of trajectories respecting the post-failure performance characteristics of the distressed airplane. The optimization pattern is used to select the optimal combination of the candidate trajectories based on the cost functions and the environmental constraints to lead the airplane to the desired landing site. Analytical performance-based equations are developed to achieve an admissible solution in emergencytrajectory planning. The goal is to provide a general optimal framework, which can enhance the flight management system by assisting the pilot to plan the most suitable and admissible trajectory to the landing site in emergency flight conditions. The effectiveness of the proposed approach is demonstrated through simulations
A Voice Communication-Augmented Simulation Framework for Aircraft Trajectory Simulation
No full textInternational audienceAircraft operations in the terminal area rely heavily on voice communications between pilots and air traffic controllers. This paper proposes a novel aircraft trajectory simulation framework by guiding the trajectory simulation following the voice command from controllers. Bayesian model selection is used for checking pilot compliances to controller commands with observed trajectories. This framework is named as Voice Communication-Augmented Simulation. The goal of the proposed study is to enable accurate trajectory predictions. The framework can act as a computer assistant for controllers to monitor pilot compliances and ensure safe operations. The proposed method is tested and validated with actual trajectory data from Sherlock Data Warehouse. The tests showed that the proposed framework can accurately simulate and monitor the flight level change of aircraft and update the approach procedure
Wind Turbine Tower Thickness and Blade Pitch Control Co-Design Optimization
No full textInternational audienceWind energy production is still a challenge, and improving the engineering practices in wind turbine design is crucial to overcome it. In a control co-design approach, as opposed to sequential design, one considers the interaction between subsystems and applies control concepts in the design process to obtain an optimal solution. This paper investigates control co-design optimization of a wind turbine blade and tower, where the power efficiency is aimed to be maximized while minimizing the system's total mass. Furthermore, bounds on the design parameters are defined to constrain structural loads to admissible values. The power efficiency can be improved by reducing the root mean squared value of the generator speed tracking error, and the mass can be modified by the tower thickness. A mixed control architecture of ∞ and reference governors is proposed to design the wind turbine control system. The ∞ technique reduces structural loads, and the use of reference governors improves the system's power efficiency and addresses actuator limitations. Finally, the benefits of the control co-design optimization method are shown
Modélisation Hybride Polynomiale du Décrochage pour la Dynamique Longitudinale d'un Drone
No full textInternational audienceModeling the longitudinal dynamics of a fixed-wing unmanned aerial vehicle (UAV) at high angles of attack is not an easy task. Indeed, when the airplane approaches stall, non-linear effects appear, including transient behaviors and an aerodynamic hysteresis. Although some models are present in the literature to address these aspects, they are usually aerodynamics-based and often too complex for analysis and control applications. Therefore, this paper presents a new hybrid polynomial formulation for the modeling of the aerodynamic coefficients. In addition, a Linearly Constrained Least Squares (LCLS) process guaranteeing continuity at the mode transitions is proposed for the identification of the model. The Hybrid Polynomial Stall Model (HPSM) is finally identified on experimental wind tunnel data, showcasing its ability to accurately predict a UAV's dynamics.Modéliser la dynamique longitudinale d'un drone à voilure fixe n'est pas tâche aisée à hauts angles d'incidence. En effet, lorsque l'appareil approche du décrochage des effets non-linéaires apparaissent, notamment des phénomènes transitoires et une hystérésis aérodynamique. Bien que divers modèles sont présents dans la littérature pour modéliser ces aspects, ils sont souvent basés sur des connaissances aérodynamiques et trop complexes pour des applications d'analyse et de commande. C'est pourquoi ce papier présente une nouvelle modélisation hybride polynomiale pour les coefficients aérodynamiques. De plus, un processus d'identification par moindres carrés sous contrainte linéaire garantissant la continuité lors du changement de mode est proposé. Le modèle est enfin identifié sur des données expérimentales en soufflerie, montrant son aptitude à prédire le comportement d'un drone
Revisiter les quorums pondérés et les reconfigurations asynchrones pour les systèmes de stockage atomique
No full textIn the era of big data, cryptocurrencies, and the internet of everything, storage systems are demanding more than ever. Since such systems are prone to various types of failures, like disk failures and failures created by malicious attacks, they should be reliable. Reliable storage systems guarantee their progress and correctness in the face of failures. Replication is the most well-known technique to construct reliable storage systems in which copies of data are stored in multiple places called servers. Each server is a cheap commodity disk or low-end PC. Distributed computing is used to design protocols to replicate and execute operations on servers, like read and write. One of the fundamental distributed reliable storage systems is the atomic storage system. Although such a storage system has only two operations, read and write, it provides the building blocks for more complex storage systems. The protocols of the atomic storage system are quorum-based. A quorum-based protocol consists of at least one phase; in one phase, a request is sent to the servers, and the phase will finish if a quorum of servers responds to the request. In the traditional protocols of the atomic storage system, a quorum is constituted by a majority of servers. The less the sizes of quorums, the higher the protocol's performance. One approach to decreasing the size of quorums is to assign weights to servers; in that situation, a quorum is constituted if a weighted majority of servers respond to the request. In practical implementations of an atomic storage system, since servers' performance changes over time, their weights should be reassigned over time as well. This thesis presents several protocols for different types of failures to reassign servers' weights over time. The correctness of the protocols is proved. Furthermore, by evaluating the protocols, it is shown that the presented protocols outperform other solutions.A l'ère des données massives, des cryptomonnaies, et de l'internet des objets, les système de stockage fiables jouent un rôle de plus en plus important. Comme ses applications sont constamment exposées aux pannes, comme un disque défaillant ou un attaque malicieux, un système de stockage fiable garantie la disponibilité et la durabilité des applications malgré les pannes. La réplication est certainement la technique la plus connue pour concevoir des systèmes de stockage fiables, où des copies des données sont sauvegardées en plusieurs nœuds différents appelés serveurs. En fait, un serveur correspondent à un simple disque ou à un PC pas cher. L'algorithmique répartie est donc utilisé pour concevoir des protocoles pour répliquer et exécuter des opérations sur des ensembles de serveurs, comme par exemple les opérations écriture et de lecture. Dans ce contexte, un système de stockage atomique, qui est un type de système de stockage distribué fiable, constitue un composant fondamental pour des nombreux systèmes de stockage. En dépit du faite que ces systèmes n'aient que deux opérations, lecture et écriture, ils sont utilisés lors de la conception des systèmes de stockage complexes. En plus, ces systèmes utilisent le concept de quorum. Ainsi, les protocoles qui utilisent ce concept ont au moins une phase. Par exemple, lorsque une requête est envoyée aux serveurs dans une phase, cette phase sera finie si un quorum de serveurs répond à cette requête. En systèmes répartis, un quorum d'un système de stockage atomique est généralement composé d'une majorité de serveurs. Par conséquent, moins il y a des serveurs pour avoir un quorum, plus grands sont les gains en performance. Une approche pour diminuer le quorum d'un système de stockage atomique consiste à attribuer des poids aux serveurs. Ainsi, un quorum est formé lorsque un majorité pondéré répond à la requête. En réalité, les poids des serveurs peuvent évoluer en fonction de leur performances au fil du temps. Cette thèse propose plusieurs protocoles pour adapter les poids des serveurs d'un système de stockage atomique soumis à différents hypothèses de pannes. La conformité des protocoles proposés est prouvée d'une façon formelle. En plus, l'évaluation des protocoles proposés suggère que l'approche entreprise est plus performante que les travaux précédents