Cette thèse s’inscrit dans le domaine de la programmation mathématique appliquée à la séparation d’aéronefs stabilisés en altitude. L’objectif est le développement d’algorithmes de résolution de conflits aériens ; l’enjeu étant d’augmenter la capacité de l’espace aérien afin de diminuer les retards et d’autoriser un plus grand nombre d’aéronefs à suivre leur trajectoire optimale. En outre, du fait de l’imprécision des prédictions relatives à la météo ou à l’état des aéronefs, l’incertitude sur les données est une caractéristique importante du problème. La démarche suivie dans ce mémoire s’attache d’abord au problème déterministe dont l’étude est nettement plus simple. Pour cela, quatre modèles basés sur la programmation non linéaire et sur la programmation linéaire à variables mixtes sont développés en intégrant notamment un critère reflétant la consommation de carburant et la durée de vol. Leur comparaison sur un ensemble de scénarios de test met en évidence l’intérêt d’utiliser un modèle linéaire approché pour l’étude du problème avec incertitudes. Un champ de vent aléatoire, corrélé en temps et en espace, ainsi qu’une erreur gaussienne sur la mesure de la vitesse sont ensuite pris en compte.Dans un premier temps, le problème déterministe est adapté en ajoutant une marge sur la norme de séparation grâce au calcul d’une approximation des probabilités de conflits. Finalement, une formulation stochastique avec recours est développée. Ainsi, les erreurs aléatoires sont explicitement incluses dans le modèle afin de tenir compte de la possibilité d’ordonner des manoeuvres de recours lorsque les erreurs observées engendrent de nouveaux conflits. / This thesis belongs to the field of mathematical programming, applied to the separation of aircraft stabilised on the same altitude. The primary objective is to develop algorithms for the resolution of air conflicts. The expected benefit of such algorithm is to increase the capacity of the airspace in order to reduce the number of late flights and let more aircraft follow their optimal trajectory. Moreover, meteorological forecast and trajectory predictions being inexact,the uncertainty on the data is an important issue. The approach that is followed focuses on the deterministic problem in the first place because it is much simpler. To do this, four nonlinear and mixed integer linear programming models, including a criterion based on fuel consumption and flight duration, are developed. Their comparison on a benchmark of scenarios shows the relevance of using an approximate linear model for the study of the problem with uncertainties.A random wind field, correlated in space and time, as well as speed measures with Gaussianerrors are then taken into account. As a first step, the deterministic problem is adapted by computinga margin from an approximate calculation of conflict probabilities and by adding it tothe reference separation distance. Finally, a stochastic formulation with recourse is developed.In this model, the random errors are explicitly included in order to consider the possibility of ordering recourse actions if the observed errors cause new conflicts.

O transporte aéreo e a indústria de sistemas de defesa foram setores pioneiros na utilização de sistemas computacionais críticos, incrementando os níveis de automação nas atividades de controle do espaço aéreo. Com o crescimento desses setores, verificado pela expansão dos números de vôos, volumes de cargas e usuários, assim como pela ampliação e diversidade das operações militares, os sistemas de controle têm assumido maior complexidade técnica, introduzindo novos recursos de automação ou facilidades adicionais de apoio para funções exercidas manualmente. Essa situação tem ampliado a dependência dos serviços prestados, relativamente à disponibilidade dos sistemas computacionais. Diretrizes de projeto e procedimentos operacionais são estabelecidos para manter os níveis de segurança nos casos de falha, no entanto a disponibilidade torna-se parâmetro crítico, na medida em que algumas falhas podem afetar a eficiência nominal da prestação dos serviços. Nesse cenário, este trabalho propõe um modelo para avaliação da disponibilidade de sistemas de controle do espaço aéreo, a partir de recursos de análises da teoria de filas. Inicialmente é citado um modelo geral para análise de disponibilidade de data centers. Em seguida, é apresentada uma extensão do modelo geral para análise da disponibilidade em sistemas de controle do espaço aéreo. Para isso, considerou-se a intervenção humana existente nessa atividade, cujas decisões de controle são exercidas por operadores qualificados (controladores), tanto nas atividades inerentes ao serviço de controle, quanto nos casos de degradação, nos quais os operadores ou técnicos de manutenção assumem alguma tarefa de reparo, decorrente da eventual indisponibilidade de funções do sistema. / Due to the growth in airspace utilization, which can be verified both in terms of the expansions in aerial movements, airports and volumes of transported passengers and cargo, as well as in terms of the expansion of military operations demands and diversity, airspace control activities have been increasing their technical complexity, introducing new features into the existent automation systems or creating additional resources for the automation of some functions previously performed by human operators. This situation has increased the dependence on the availability of the computer systems involved in the services provided by control centers. Project directives and operational procedures are established in order to maintain the safety integrity levels of the systems, in case any failure occurs. However, the availability becomes a critical parameter, once failure events can force an undesirable state of degraded operation, jeopardizing the nominal capacity of the services being performed through any controlled airspace. In this scenario, this work presents an availability model for the computer systems used in airspace control centers, based on analysis from queuing theory. A general model is first presented, referencing a case study that describes the use of queuing models to access the availability of generic data centers. Further considerations are introduced to extend this general model in order to propose its application for the specific computer systems used in airspace control centers, where operational control relies on human activities. In this case, system operation involves intensive use of human-machine interfaces (HMI), for the regular control services provided, and additional technical or operational maintenance activities, occasionally imposed to repair a momentary loss of any function of the system.

Com o crescimento do setor aeronáutico faz-se necessário a criação de novas tecnologias para que a capacidade do sistema possa aumentar sem provocar perdas nos níveis de segurança. Para isso foi criado o CNS/ATM, um paradigma que integra tecnologias de comunicação, navegação e vigilância em um sistema de gerenciamento de tráfego aéreo global. No âmbito das comunicações entre controlador e piloto, o atual sistema de fonia via rádio analógico é substituído por um enlace de dados, chamado de Controller-Pilot Data Link Communication (CPDLC). Esta alteração promove polêmica entre aeronautas e autoridades, de forma que é essencial um estudo aprofundado que comprove sua eficácia. Dessa forma, esta pesquisa visa avaliar a segurança do CPDLC quando utilizado em Áreas Terminais do Espaço Aéreo. Para a realização desta pesquisa, foi criada uma metodologia de avaliação de segurança utilizando simuladores de voo, de tráfego aéreo e de comunicação CPDLC combinados com uma análise por meio de modelos de Markov. O procedimento de chegada ao aeroporto de Congonhas, situado na Terminal São Paulo, foi utilizado como referência para aplicação desta metodologia. Os resultados obtidos mostraram que o sistema atual de comunicação, via voz, está no limite do atendimento dos níveis internacionais de segurança para a demanda atual. Contudo, a comunicação por enlace de dados atende, e em alguns casos inclusive melhora, o nível de segurança desta região do espaço aéreo. / With the growth of the aviation industry it is necessary to create new technologies that can increase the system capacity without loss in the safety levels. Because of this the CNS/ATM was created, a paradigm that integrates communication, navigation and surveillance technologies with a global air traffic management. For the communications between controllers and pilots, the current system of voice over analog radio is being replaced by a data link, called the Controller-Pilot Data Link Communication (CPDLC). This replacement raises debates between airmen and authorities, demanding a detailed study that proves its effectiveness. Thus, this research aims to evaluate the CPDLC safety when used in Terminal Airspace Areas. For this research, was created a methodology for security assessment using flight, air traffic, and CPDLC simulators combined with a Markov model analysis. The Congonhas airport arrival procedure, located in São Paulo Terminal, was used as reference for this methodology application. The results showed that the current system of voice communication is on the limit of fulfilling the international safety levels for the current demand. However, the data link communication addresses, and in some cases even improve, the safety level for this airspace region.

Les contrôleurs du trafic aérien ou « aiguilleurs du ciel », dont l’activité consiste à assurer la sécurité de l’écoulement du trafic aérien, vont bientôt être confrontés à une évolution sans précédent de leur activité de travail. Pour pallier à une évolution de contexte, associée principalement à une augmentation significative du niveau de trafic aérien, la construction d’un nouvel environnement de contrôle induisant l’introduction de nouvelles technologies et de l’automatisation partielle de la tâche de contrôle est visée. Ces perspectives, qui ont pour objectif de diminuer les sollicitations des contrôleurs aériens afin d’augmenter le seuil capacitaire de gestion du trafic aérien, suscitent l’interrogation. Notamment, comment assurer la validation de ces évolutions en vue des objectifs visés ? Ce doctorat porte sur l’étude de la charge mentale de contrôleurs aériens dans différents contextes, afin d’évaluer les effets engendrés par de telles modifications apportées à leur environnement de travail quotidien. L’évaluation proposée repose sur une approche multidimensionnelle centrée sur l’analyse de paramètres oculaires enregistrés grâce à une technique d’eye-tracking dans des situations de contrôle écologiquement valides, en référence à la tâche de contrôle du trafic aérien. La première étude a tout d’abord permis de caractériser la gestion de la charge mentale effectuée par les contrôleurs aériens au cours de leur activité dans une situation nominale (reflétant la situation de contrôle du trafic aérien actuelle). La deuxième étude porte sur les effets générés par l’introduction de nouveaux systèmes informatisés d’aide à la décision induisant une automatisation partielle de la tâche de contrôle. Enfin, la dernière étude souligne l’effet du niveau de formation sur les modes de gestion des ressources cognitives employés par les contrôleurs aériens. / The air traffic controllers, whose job is to ensure the safety of air traffic flow, will soon be faced to an unprecedented change in their work activity. To compensate a change of context, mainly associated with a significant increase of the air traffic density, the elaboration of a new air traffic control environment is considered. In particular, the introduction of new technologies (all electronic devices) causing the partial automation of the control task, has been defined as prospects for the En-Route air traffic control work position. These perspectives aim at reducing the air traffic controllers’ requirements in order to increase the capability threshold of air traffic management associated with air traffic control service rendered. Such a change may however query. Indeed, how to ensure the validation of these developments to the objectives? This research aims to study the air traffic controllers’ mental workload in different contexts. The objective of this approach is to assess the effects caused by such changes in the air traffic controllers’ daily work environment. The proposed assessment is based on a multidimensional approach mainly focused on the analysis of ocular parameters recorded through an eye-tracking technique in air traffic control situations ecologically valid with reference to the features of air traffic control task. The results deduced from the empirical work of this research were first used to characterize the management of mental workload carried by air traffic controllers during their activity in the nominal situation (reflecting the current air traffic control situation). The results obtained through this research also focused on the effects generated by the introduction of new computerized systems inducing a partial automation of the control task, and those induced by the level of training dedicated to the use of such systems on the management methods of cognitive resources employed by air traffic controllers.

Com o crescimento do setor aeronáutico faz-se necessário a criação de novas tecnologias para que a capacidade do sistema possa aumentar sem provocar perdas nos níveis de segurança. Para isso foi criado o CNS/ATM, um paradigma que integra tecnologias de comunicação, navegação e vigilância em um sistema de gerenciamento de tráfego aéreo global. No âmbito das comunicações entre controlador e piloto, o atual sistema de fonia via rádio analógico é substituído por um enlace de dados, chamado de Controller-Pilot Data Link Communication (CPDLC). Esta alteração promove polêmica entre aeronautas e autoridades, de forma que é essencial um estudo aprofundado que comprove sua eficácia. Dessa forma, esta pesquisa visa avaliar a segurança do CPDLC quando utilizado em Áreas Terminais do Espaço Aéreo. Para a realização desta pesquisa, foi criada uma metodologia de avaliação de segurança utilizando simuladores de voo, de tráfego aéreo e de comunicação CPDLC combinados com uma análise por meio de modelos de Markov. O procedimento de chegada ao aeroporto de Congonhas, situado na Terminal São Paulo, foi utilizado como referência para aplicação desta metodologia. Os resultados obtidos mostraram que o sistema atual de comunicação, via voz, está no limite do atendimento dos níveis internacionais de segurança para a demanda atual. Contudo, a comunicação por enlace de dados atende, e em alguns casos inclusive melhora, o nível de segurança desta região do espaço aéreo. / With the growth of the aviation industry it is necessary to create new technologies that can increase the system capacity without loss in the safety levels. Because of this the CNS/ATM was created, a paradigm that integrates communication, navigation and surveillance technologies with a global air traffic management. For the communications between controllers and pilots, the current system of voice over analog radio is being replaced by a data link, called the Controller-Pilot Data Link Communication (CPDLC). This replacement raises debates between airmen and authorities, demanding a detailed study that proves its effectiveness. Thus, this research aims to evaluate the CPDLC safety when used in Terminal Airspace Areas. For this research, was created a methodology for security assessment using flight, air traffic, and CPDLC simulators combined with a Markov model analysis. The Congonhas airport arrival procedure, located in São Paulo Terminal, was used as reference for this methodology application. The results showed that the current system of voice communication is on the limit of fulfilling the international safety levels for the current demand. However, the data link communication addresses, and in some cases even improve, the safety level for this airspace region.

O transporte aéreo e a indústria de sistemas de defesa foram setores pioneiros na utilização de sistemas computacionais críticos, incrementando os níveis de automação nas atividades de controle do espaço aéreo. Com o crescimento desses setores, verificado pela expansão dos números de vôos, volumes de cargas e usuários, assim como pela ampliação e diversidade das operações militares, os sistemas de controle têm assumido maior complexidade técnica, introduzindo novos recursos de automação ou facilidades adicionais de apoio para funções exercidas manualmente. Essa situação tem ampliado a dependência dos serviços prestados, relativamente à disponibilidade dos sistemas computacionais. Diretrizes de projeto e procedimentos operacionais são estabelecidos para manter os níveis de segurança nos casos de falha, no entanto a disponibilidade torna-se parâmetro crítico, na medida em que algumas falhas podem afetar a eficiência nominal da prestação dos serviços. Nesse cenário, este trabalho propõe um modelo para avaliação da disponibilidade de sistemas de controle do espaço aéreo, a partir de recursos de análises da teoria de filas. Inicialmente é citado um modelo geral para análise de disponibilidade de data centers. Em seguida, é apresentada uma extensão do modelo geral para análise da disponibilidade em sistemas de controle do espaço aéreo. Para isso, considerou-se a intervenção humana existente nessa atividade, cujas decisões de controle são exercidas por operadores qualificados (controladores), tanto nas atividades inerentes ao serviço de controle, quanto nos casos de degradação, nos quais os operadores ou técnicos de manutenção assumem alguma tarefa de reparo, decorrente da eventual indisponibilidade de funções do sistema. / Due to the growth in airspace utilization, which can be verified both in terms of the expansions in aerial movements, airports and volumes of transported passengers and cargo, as well as in terms of the expansion of military operations demands and diversity, airspace control activities have been increasing their technical complexity, introducing new features into the existent automation systems or creating additional resources for the automation of some functions previously performed by human operators. This situation has increased the dependence on the availability of the computer systems involved in the services provided by control centers. Project directives and operational procedures are established in order to maintain the safety integrity levels of the systems, in case any failure occurs. However, the availability becomes a critical parameter, once failure events can force an undesirable state of degraded operation, jeopardizing the nominal capacity of the services being performed through any controlled airspace. In this scenario, this work presents an availability model for the computer systems used in airspace control centers, based on analysis from queuing theory. A general model is first presented, referencing a case study that describes the use of queuing models to access the availability of generic data centers. Further considerations are introduced to extend this general model in order to propose its application for the specific computer systems used in airspace control centers, where operational control relies on human activities. In this case, system operation involves intensive use of human-machine interfaces (HMI), for the regular control services provided, and additional technical or operational maintenance activities, occasionally imposed to repair a momentary loss of any function of the system.

Markov processes have been widely studied and used for modeling problems. A Markov process has two main components (i.e., an evolution law and an initial distribution). Markov processes are not suitable for modeling some problems, for example, the problem of predicting a trajectory with a known destination. Such a problem has three main components: an origin, an evolution law, and a destination. The conditionally Markov (CM) process is a powerful mathematical tool for generalizing the Markov process. One class of CM processes, called $CM_L$, fits the above components of trajectories with a destination. The CM process combines the Markov property and conditioning. The CM process has various classes that are more general and powerful than the Markov process, are useful for modeling various problems, and possess many Markov-like attractive properties. Reciprocal processes were introduced in connection to a problem in quantum mechanics and have been studied for years. But the existing viewpoint for studying reciprocal processes is not revealing and may lead to complicated results which are not necessarily easy to apply. We define and study various classes of Gaussian CM sequences, obtain their models and characterizations, study their relationships, demonstrate their applications, and provide general guidelines for applying Gaussian CM sequences. We develop various results about Gaussian CM sequences to provide a foundation and tools for general application of Gaussian CM sequences including trajectory modeling and prediction. We initiate the CM viewpoint to study reciprocal processes, demonstrate its significance, obtain simple and easy to apply results for Gaussian reciprocal sequences, and recommend studying reciprocal processes from the CM viewpoint. For example, we present a relationship between CM and reciprocal processes that provides a foundation for studying reciprocal processes from the CM viewpoint. Then, we obtain a model for nonsingular Gaussian reciprocal sequences with white dynamic noise, which is easy to apply. Also, this model is extended to the case of singular sequences and its application is demonstrated. A model for singular sequences has not been possible for years based on the existing viewpoint for studying reciprocal processes. This demonstrates the significance of studying reciprocal processes from the CM viewpoint.

This dissertation presents a suite of design tools for multi-agent systems that address three main areas: network design, decentralized controller generation, and the synthesis of decentralized control strategies by combining individual decentralized controllers. First, a new metric for quantifying heterogeneity in multi-agent systems is presented based on combining different notions of entropy, and is shown to overcome the drawbacks associated with existing diversity metrics in various scientific fields. Moreover, a new method of controlling multi-agent networks through the single-leader network paradigm is presented where by directly exploiting the homogeneity of agent capabilities, a network which is not completely controllable can be driven closer to a desired target configuration than by using traditional control techniques. An algorithm is presented for generating decentralized control laws that allow for agents to best satisfy a desired global objective, while taking into account network topological constraints and limitations on how agents can compute their control signals. Then, a scripting tool is developed to aid in specifying sequences of decentralized controllers to be executed consecutively, while helping ensure that the required network topological requirements needed for each controller to execute properly are maintained throughout mode switches. Finally, the underlying concepts behind the developed tools are showcased in three example applications: distributed merging and spacing for heterogeneous aircraft during terminal approaches, collaborative multi-UAV convoy protection in dynamic environments, and an educational tool used to teach a graduate-level networked controls course at the Georgia Institute of Technology.

Abstract: This thesis addresses the problem of graceful degradation for air traffic management systems (ATMS). The graceful degradation is the process by which the safety of the airspace is ensured in the event of failures or operational degradation in the system. After listing the main areas where failures and degradation can affect the ATMS, an ontology of the ATMS is proposed. The ontology allows to introduce failures at different levels, track their propagation throughout the system, and measure their operational impact. Then, two operational degradations are studied: The first degradation studied is a reduction in the landing capacity at San Francisco International Airport. The aircraft queueing process for terminal area is modeled and optimized to ensure a graceful degradation. The second degradation encompasses Communication, Navigation and Surveillance systems failures. The graceful degradation is ensured by increasing the spacing distance between aircraft, using novel algorithms of avoidance under uncertainties. Those algorithm also serve as probes to compare the degradation capabilities of different traffic configurations such as Miles-In-Trail and Free-Flight arrivals. Finally, this thesis focuses on monitoring the airspace for potential degradation. The ability and the difficulty of en-route traffic configuration are evaluated using degradation maps. Those maps can be used controller to rapidly and efficiently steer traffic from nominal mode of operations to mode of operations under abnormal conditions. Finally, a monitoring tool for terminal area is presented: the conformance of current flight to pre-identified typical operations is determined in real time. As the number of non-conforming aircraft increases, the complexity seen by air traffic controllers increases, and can become a threat for the airspace safety.

In response to the unparalleled growth of demand for air traffic during the past few decades, the Federal Aviation Administration (FAA) launched the Next Generation Air Transportation (NextGen) program to restructure the National Airspace System (NAS). Among the research is the focus on direct, wind optimal routing using geodesic routes and flight operations that do not depend solely on ground based navigation aids (NAVAID) and a fixed airspace structure. While technologies, such as the Global Positioning System (GPS), exist to locate an aircraft at higher degrees of resolution with a larger coverage, the way in which this information is conveyed is long and cumbersome. Therefore, new ways to describe the airspace is desired. The thesis presents the results of an experimental investigation into three alternatives to fix/route and GPS methods. The first method is the Navigation Reference System (NRS) using an absolute grid based strategy that has been recently implemented in limited portions of the United States airspace. The second method, the Military Grid Reference System (MGRS), is also a grid based system, and it is used by NATO, but it has not been applied to the air traffic control context. The third alternative is Point Relation Navigation (PRN), which uses a single point of reference within each Air Route Traffic Center (ARTCC) airspace and acts as a hybrid of coordinate and radial fixes. 21 airline dispatchers from a single major U.S air carrier participated in an online assessment of the five methods above through specific tasks. Results indicate that most participants prefer the fix/route system over the others, followed closely by the PRN method. However, there were varying results across all of the methods in terms of speed and accuracy of completing the tasks. This study incites further interest in strategies to describe aircraft routes operating in a more flexible airspace.