Le siècle dernier a été le siècle de la révolution technologique. Les combustibles fossiles ont alimenté cette révolution technologique. Les défis auxquels notre société est confrontée, que ce soit le changement climatique ou la situation énergétique mondiale ou l’épuisement des réserves de combustibles fossiles, sont les défis les plus graves auxquels sont confrontés toutes les générations. L'énergie renouvelable est considérée comme la clé des problèmes énergétiques de notre société. De nombreuses technologies innovantes se font concurrence pour alimenter la prochaine révolution énergétique. Sources d'énergies renouvelables telles que l'énergie solaire, l'énergie éolienne, la biomasse, l'hydroélectricité, l'énergie géothermique, etc. Presque tous sont saisonniers, et sont donc des sources d'énergie discontinues et non uniformes. Ils ont également une limitation en termes de choix des sites de production et, en général, nécessitent de grandes étendues de terre pour les plantes, ce qui conduit à une faible densité de puissance par unité de surface.Néanmoins, l'énergie éolienne et solaire a beaucoup attiré l'attention au cours des dernières décennies. Cependant, pour que le monde passe complètement des énergies fossiles et de l’énergie nucléaire à l’énergie éolienne et solaire, il est nécessaire de développer de nouveaux types de systèmes capables de générer de l’énergie à moindre coût avec moins de contraintes de sélection de sites.Dans la quête de la source d'énergie pérenne. Notre société se tourne vers la communauté scientifique pour des solutions innovantes. Cette thèse est une étape vers la recherche de solutions innovantes à nos problèmes énergétiques. Les systèmes d'énergie éolienne à haute altitude (HAWE) ou plus communément appelés systèmes éoliens aéroportés (AWES) sont considérés comme la réponse aux besoins énergétiques des générations futures. L'énergie éolienne aéroportée (AWE) est un concept innovant visant à utiliser l'énergie des courants de vent à haute altitude, car les courants de vent à haute altitude sont presque uniformes dans le monde entier et AWES peut pratiquement être installé partout dans le monde. De plus, les systèmes AWE proposés nécessitent moins de matériau de structure. Ils devraient donc être beaucoup moins chers que toute autre source d’énergie disponible. AWE est donc une perspective prometteuse dans cette quête pour trouver une solution à nos problèmes énergétiques.Dans ce travail, la faisabilité des systèmes d'énergie éolienne aéroportés basés sur Magnus est explorée. Le travail présente en détail un bref historique des systèmes d'énergie éolienne aéroportés et des concepts de base nécessaires pour développer une compréhension de la technologie AWE. Il examine en détail les systèmes aéroportés basés sur Magnus et donne une perspective historique sur les machines basées sur l’effet Magnus. Il présente en détail les propriétés aérodynamiques de l’effet Magnus et présente un modèle aérodynamique pour ces systèmes. Puisque la modélisation est un aspect important de toute technologie. Ce travail présente un modèle détaillé des systèmes AWE basés sur Magnus ainsi que les algorithmes de contrôle nécessaires au fonctionnement de tels systèmes. Les courbes de puissance sont des outils couramment utilisés pour analyser les systèmes d'énergie éolienne. Ce travail présente une approche pour la conception de courbes de puissance pour les systèmes AWE afin d'analyser les capacités de production d'énergie des systèmes d'énergie éolienne aéroportés. / Last century has been the century of the technology revolution. Fossil fuels have fueled this technology revolution. The challenges faced by our society be it the climate change or the world energy situation or the depletion of fossil fuel reserves are the most grievous challenges faced by any generation. Renewable energy is believed to be the key to energy problems of our society. There are many innovative technologies competing against each other to fuel the next energy revolution. Renewables sources of energies such as solar, wind, biomass, hydropower, geothermal etc. Though promising but due to the high economic cost and limited application they are yet to prove their mass scale applicability. Almost all of them are seasonal, hence, are discontinuous and non-uniform sources of energy. They also have a limitation in terms of choice of plant sites, and generally, require large tracts of land for plants which lead to low power density per unit area.Nonetheless, Wind and Solar energy have attracted a lot of attention in the last few decades. However, for the world to fully shift from fossil fuels and nuclear energy to Wind and Solar power, it is necessary to develop new kind of systems which can generate continuous power at a lower cost with fewer site selection constraints.In the quest to find the perennial clean source of energy. Our society is looking towards the scientific community for innovative solutions. This thesis is one such step towards finding innovative solutions to our energy problems. High altitude wind energy systems (HAWE) or more commonly known as Airborne wind energy systems (AWES) are believed to be the answer to the energy needs of the future generations. Airborne wind energy (AWE) is an innovative concept aiming at utilizing the energy of the high altitude wind currents, as high altitude wind currents are almost uniform across the globe, and AWES can be practically set-up anywhere around the world. Also, the proposed AWE systems require less structural material. Thus, they are expected to be much cheaper than any other available energy source. Therefore, AWE is a promising prospect in this quest to find a solution to our energy problems.In this work, the feasibility of Magnus-based airborne wind energy systems is explored. The work presents in detail a brief history of Airborne wind energy systems and the basic concepts needed to develop an understanding about the AWE technology. It discusses in detail Magnus-based airborne systems and gives a historical perspective on the Magnus-effect based machines. It discusses in detail the aerodynamical properties of the Magnus effect and presents an aerodynamic model for such systems. Since modeling is an important aspect of any technology. This work presents a detailed model of the Magnus-based AWE systems along with the control algorithms required for the operation of such systems. A common tool used to analyze wind-based energy systems is power curves. This work presents an approach to design power curves for AWE systems in order to analyze the power producing capabilities of Airborne wind energy systems.

Esta dissertação apresenta o desenvolvimento da teoria de dinâmica de voo e o conceito de controle a ser aplicado na modelagem e simulação de voo de um VANT com decolagem e pouso vertical proposto. Um conceito de aeronave de asa semi-tandem é projetado e os coeficientes aerodinâmicos, propriedades inerciais e parâmetros de controle são estimados, o que permitiu a implementação da teoria proposta. O modelo fez uso das equações de movimento multi-corpos onde a aeronave é dividida em partes de forma que a asa, o estabilizador horizontal e os rotores sejam entidades independentes. Além disso, o sucesso da fase de transição de voo pairado para cruzeiro e de cruzeiro para voo pairado pode ser verificado se houver a possibilidade da aeronave trimar ao longo do regime de velocidades de voo, em outras palavras, se houver uma combinação de estados de movimento que mantenha a aeronave estável do voo pairado para a condição de cruzeiro. Assim, as curvas de trimagem que expressam os estados são calculadas usando a minimização de uma função de custo envolvendo a soma dos quadrados de alguns dos estados de movimento, definidos pelas equações de movimento mencionadas anteriormente. Tal minimização é realizada usando o algoritmo Simplex Sequencial. Além disso, é apresentada uma estratégia de controle que estabiliza a aeronave durante a transição de voo pairado para configuração de cruzeiro, que é testada em simulação computacional de um voo longitudinal acelerado e desacelerado, ou seja, de voo pairado para cruzeiro e de cruzeiro para voo pairado. Finalmente, um protótipo da aeronave estudada é apresentado. / This thesis presents the development of the flight dynamics theory and control concept to be applied in the modeling and flight simulation of a proposed VTOL UAV. A semi-tandem wing aircraft concept is designed and the aerodynamic coefficients, inertial properties and controls parameters are estimated, which allowed the implementation of the proposed theory. The model made use of the multi-body equations of motion where the aircraft is divided in parts so that the wing, horizontal stabilizer and rotors are independent entities. Additionally, the success of the transition phase from hovering to cruise and from cruise to hovering can be verified if there is the possibility of the aircraft to trim along the flight speed regime, in other words, if there is a combination of states of motion that keep the aircraft stable from hover to cruise condition. So, the trim curves expressing the states are computed using the minimization of a cost function involving the sum of the squares of some of the states of motion, defined through the equations of motion previously mentioned. Such minimization is performed using the Sequential Simplex algorithm. Moreover, a control strategy that stabilizes the aircraft while it transitions from hovering to cruise configuration is presented, which is tested in computer simulation of an accelerated and decelerated longitudinal flight, that is, from hovering to cruise condition, and from cruise to hovering condition. Finally, a prototype of the aircraft studied is presented.

In this work we investigate the use of state-of-the-art tools for the regulation of complex, non-linear systems to improve the methodologies currently applied to trim comprehensive virtual prototypes of rotors and rotorcrafts. Among the several methods that have been proposed in the literature, the auto-pilot approach has the potential to solve trim problems efficiently even for the large and complex vehicle models of modern comprehensive finite element-based analysis codes. In this approach, the trim condition is obtained by adjusting the controls so as to virtually ``fly' the system to the final steady (periodic) flight condition. Published proportional auto-pilots show to work well in many practical instances. However, they cannot guarantee good performance and stability in all flight conditions of interest. Limit-cycle oscillations in control time histories are often observed in practice because of the non-linear nature of the problem and the difficulties in enforcing the constant-in-time condition for the controls. To address all the above areas of concern, in this research we propose a new auto-pilot, based on non-linear model-predictive control (NMPC). The formulation uses a non-linear reference model of the system augmented with an adaptive neural element, which identifies and corrects the mismatch between reduced model and controlled system. The methodology is tested on the wind-tunnel trim of a rotor multibody model and compared to an existing implementation of a classic auto-pilot. The proposed controller shows good performance without the need of a potentially very expensive tuning phase, which is required in classical auto-pilots. Moreover, model-predictive control provides a framework for guaranteeing stability of the non-linear closed-loop system, so it seems to be a viable approach for trimming complete rotorcraft comprehensive models in free-flight.

A supercavitating vehicle, a next-generation underwater vehicle capable of changing the paradigm of modern marine warfare, exploits supercavitation as a means to reduce drag and achieve extremely high submerged speeds. In supercavitating flows, a low-density gaseous cavity entirely envelops the vehicle and as a result the vehicle is in contact with liquid water only at its nose and partially over the afterbody. Hence, the vehicle experiences a substantially reduced skin drag and can achieve much higher speed than conventional vehicles. The development of a controllable and maneuvering supercavitating vehicle has been confronted with various challenging problems such as the potential instability of the vehicle, the unsteady nature of cavity dynamics, the complex and non-linear nature of the interaction between vehicle and cavity. Furthermore, major questions still need to be resolved regarding the basic configuration of the vehicle itself, including its control surfaces, the control system, and the cavity dynamics. In order to answer these fundamental questions, together with many similar ones, this dissertation develops an integrated simulation-based design tool to optimize the vehicle configuration subjected to operational design requirements, while predicting the complex coupled behavior of the vehicle for each design configuration. Particularly, this research attempts to include maneuvering flight as well as various operating trim conditions directly in the vehicle configurational optimization. This integrated approach provides significant improvement in performance in the preliminary design phase and indicates that trade-offs between various performance indexes are required due to their conflicting requirements. This dissertation also investigates trim conditions and dynamic characteristics of supercavitating vehicles through a full 6 DOF model. The influence of operating conditions, and cavity models and their memory effects on trim is analyzed and discussed. Unique characteristics are identified, e.g. the cavity memory effects introduce a favorable stabilizing effect by providing restoring fins and planing forces. Furthermore, this research investigates the flight envelope of a supercavitating vehicle, which is significantly different from that of a conventional vehicle due to different hydrodynamic coefficients as well as unique operational conditions.

This work addressed aerodynamic modeling methods for prediction of post-stall flight dynamics of large transport aircraft. This was accomplished by applying historically successful modeling methods used on high-performance military aircraft to a transport configuration. The overall research approach involved integrating forced oscillation and rotary balance wind tunnel data into an aerodynamic model using several methods of blending these data. The complete aerodynamic model was integrated into a six degree-of-freedom simulation. Experimental data from free-spin wind tunnel testing was used to validate the aerodynamic modeling methods by comparing aerodynamic force and moment coefficients and also to validate the simulation performance by comparing spin mode characteristics and time histories. The aerodynamic model prediction of spin dynamics was generally very good using all of the blending methods studied. In addition, key spin mode characteristics were predicted with a high degree of accuracy. Overall, using the Hybrid Kalviste method of blending forced oscillation and rotary balance data produced the closest match to the free-spin data when comparing aerodynamic coefficients and spin mode characteristics. Several issues were encountered with the blending methods that were exacerbated by nonlinearities and asymmetries in the dynamic aerodynamic data. A new method of looking up dynamic aerodynamic data was proposed to address shortcomings in the blending methods and recommendations were provided on addressing issues with the dynamic aerodynamic data.

<p> This work focuses on solving the general optimal control problems with smart-learning-enabled and theory-supported optimal control (SET-OC) approaches. The proposed SET-OC includes two main directions. Firstly, according to the basic idea of the direct method, the smart-learning-enabled iterative optimization algorithm (SEIOA) is proposed for solving discrete optimal control problems. Via discretization and reformulation, the optimal control problem is converted into a general quadratically constrained quadratic programming (QCQP) problem. Then, the SEIOA is applied to solving QCQPs. To be specific, first, a structure-exploiting decomposition scheme is introduced to reduce the complexity of the original problem. Next, an iterative search, combined with an intersection-cutting plane, is developed to achieve global convergence. Furthermore, considering the implicit relationship between the algorithmic parameters and the convergence rate of the iterative search, deep learning is applied to design the algorithmic parameters from an appropriate amount of training data to improve convergence property. To demonstrate the effectiveness and improved computational performance of the proposed SEIOA, the developed algorithms have been implemented in extensive real-world application problems, including unmanned aerial vehicle path planning problems and general QCQP problems. According to the theoretical analysis of global convergence and the simulation results, the efficiency, robustness, and improved convergence rate of the optimization framework compared to the state-of-the-art optimization methods for solving general QCQP problems are analyzed and verified. Secondly, the onboard learning-based optimal control method (L-OCM) is proposed to solve the optimal control problems. Supported by the optimal control theory, the necessary conditions of optimality for optimal control of the optimal control problem can be derived, which leads to two two-point-boundary-value-problems (TPBVPs). Then, critical parameters are identified to approximate the complete solutions of the TPBVPs. To find the implicit relationship between the initial states and these critical parameters, deep neural networks are constructed to learn the values of these critical parameters in real-time with training data obtained from the offline solutions.  To demonstrate the effectiveness and improved computational performance of the proposed L-OCM approaches, the developed algorithms have been implemented in extensive real-world application problems, including two-dimensional human-Mars entry, powered-descent, landing guidance problems, and fuel-optimal powered descent guidance (PDG) problems. In addition, considering there is no thorough analysis of the properties of the optimal control profile for PDG when considering the state constraints, a rigid theoretical analysis of the fuel-optimal PDG problem with state constraints is further provided. According to the theoretical analysis and simulation results, the optimality, robustness, and real-time performance of the proposed L-OCM are analyzed and verified, which indicates the potential for onboard implementation. </p>

A flapping-wing micro-air-vehicle (FWMAV) represents a complex multi-disciplinary system whose analysis invokes the frontiers of the aerospace engineering disciplines. From the aerodynamic point of view, a nonlinear, unsteady flow is created by the flapping motion. In addition, non-conventional contributors, such as the leading edge vortex, to the aerodynamic loads become dominant in flight. On the other hand, the flight dynamics of a FWMAV constitutes a nonlinear, non-autonomous dynamical system. Furthermore, the stringent weight and size constraints that are always imposed on FWMAVs invoke design with minimal actuation. In addition to the numerous motivating applications, all these features of FWMAVs make it an interesting research point for engineers. In this Dissertation, some challenging points related to FWMAVs are considered. First, an analytical unsteady aerodynamic model that accounts for the leading edge vortex contribution by a feasible computational burden is developed to enable sensitivity and optimization analyses, flight dynamics analysis, and control synthesis. Second, wing kinematics optimization is considered for both aerodynamic performance and maneuverability. For each case, an infinite-dimensional optimization problem is formulated using the calculus of variations to relax any unnecessary constraints induced by approximating the problem as a finite-dimensional one. As such, theoretical upper bounds for the aerodynamic performance and maneuverability are obtained. Third, a design methodology for the actuation mechanism is developed. The proposed actuation mechanism is able to provide the required kinematics for both of hovering and forward flight using only one actuator. This is achieved by exploiting the nonlinearities of the wing dynamics to induce the saturation phenomenon to transfer energy from one mode to another. Fourth, the nonlinear, time-periodic flight dynamics of FWMAVs is analyzed using direct and higher-order averaging. The region of applicability of direct averaging is determined and the effects of the aerodynamic-induced parametric excitation are assessed. Finally, tools combining geometric control theory and averaging are used to derive analytic expressions for the textit{Symmetric Products}, which are vector fields that directly affect the acceleration of the averaged dynamics. A design optimization problem is then formulated to bring the maneuverability index/criterion early in the design process to maximize the FWMAV maneuverability near hover. / Ph. D.

<p dir="ltr">In the pursuit of establishing a sustainable space economy within the cislunar region, it is vital to formulate transfer design strategies that uncover economically viable highways between different regions of the space domain. The inherent complexity of spacecraft dynamics in the cislunar space poses challenges in determining feasible transfer options. However, the motion characterized by known dynamical structures modeled through the circular restricted three-body problem (CR3BP) aids in the identification of pathways with reasonable maneuver costs and flight times. A framework is proposed that incorporates a quasi-periodic orbit (QPOs) as an option to design transfer scenarios. This investigation focuses on the construction of transfers between periodic orbits. The framework is exemplified by the construction of pathways between an L2 9:2 synodic resonant Near-Rectilinear Halo Orbit (NRHO) and a planar Moon-centered Distant Retrograde Orbit (DRO). The innate difference in the geometries of the departure and arrival orbits of the sample case, along with the lack of natural flows towards and away from them, imply that links between these orbits may necessitate costly maneuvers. A strategy is formulated that leverages the stable and unstable manifolds associated with intermediate periodic orbits and quasi-periodic orbits to construct end-toend trajectories. As part of this strategy, a systematic methodology is outlined to streamline the determination of transfer options provided by the 5-dimensional manifolds associated with a QPO family. This approach reveals multiple local basins of solutions, both interior and exterior-types, characterized by selected intermediate orbits. The construction of transfers informed by the manifolds associated with QPOs is more intricate than those based on periodic orbits. However, QPO-derived solutions allow for the recognition of alternative local basins of solutions and often offer more cost-effective transfer options when compared to trajectories designed using periodic orbits that underlie the QPOs.</p>

<p>The use of lower airspace for air taxi and cargo applications opens up exciting prospects for futuristic Unmanned Aircraft Systems (UAS). However, ensuring the safety and security of these UAS within densely populated urban areas presents significant challenges. Most modern aircraft systems, whether unmanned or otherwise, rely on the Global Navigation Satellite System (GNSS) as a primary sensor for navigation. From satellite navigations point of view, the dense urban environment compromises positioning accuracy due to signal interference, multipath effects, etc. Furthermore, civilian GNSS receivers are susceptible to spoofing attacks since they lack encryption capabilities. Therefore, in this thesis, we focus on examining the safety and cybersecurity assurance of UAS in dense urban environments, from both theoretical and experimental perspectives. </p> <p>To facilitate the verification and validation of the UAS, the first part of the thesis focuses on the development of a realistic GNSS sensor emulation using a Gazebo plugin. This plugin is designed to replicate the complex behavior of the GNSS sensor in urban settings, such as multipath reflections, signal blockages, etc. By leveraging the 3D models of the urban environments and the ray-tracing algorithm, the plugin predicts the spatial and temporal patterns of GNSS signals in densely populated urban environments. The efficacy of the plugin is demonstrated for various scenarios including routing, path planning, and UAS cybersecurity. </p> <p>Subsequently, a robust state estimation algorithm for dynamical systems whose states can be represented by Lie Groups (e.g., rigid body motion) is presented. Lie groups provide powerful tools to analyze the complex behavior of non-linear dynamical systems by leveraging their geometrical properties. The algorithm is designed for time-varying uncertainties in both the state dynamics and the measurements using the log-linear property of the Lie groups. When unknown disturbances are present (such as GNSS spoofing, and multipath effects), the log-linearization of the non-linear estimation error dynamics results in a non-linear evolution of the linear error dynamics. The sufficient conditions under which this non-linear evolution of estimation error is bounded are derived, and Lyapunov stability theory is employed to design a robust filter in the presence of an unknown-but-bounded disturbance. </p>

In-orbit calibrations of space instruments are often necessary to ensure the accuracy of the measurements. The Moon provides a target with very predictable characteristics. In this report, the opportunities to perform in-orbit lunar calibrations of the MicroCarb instrument are evaluated and a procedure for conducting the Mission Planning for these calibrations is developed. Through modeling the spacecraft in its orbit, simulations show that continuous observation sequences of up to 48 minutes can be expected each lunation. The variability of the optical properties of the Moon during an opportunity is related to the orientation of the plane of the orbit of the spacecraft with respect to the cone with axis the Moon-Sun direction and apex the center of the Moon that contains the spacecraft. Choosing a value of the phase angle (Sun-Moon-Spacecraft angle) around −20 degrees to plan the lunar calibrations allows to minimize the variations of apparent radiance of the Moon during the observation. The results make it possible to refine the choice of the best moments to plan the lunar calibrations. This also allows the satellite operations team to anticipate the planning of lunar calibrations on the scale of several months. / Kalibreringar i omloppsbana för rymdinstrument är ofta nödvändiga för att säkerställa mätningarnas noggrannhet. Månen utgör ett kalibreringsmål med mycket förutsägbara egenskaper. I denna rapport utvärderas möjligheterna att utföra månkalibreringar i omloppsbana för MicroCarb-instrumentet och ett förfarande för genomförande av uppdragsplanering för dessa kalibreringar har utvecklats. Genom att modellera rymdfarkosten i sin bana visar simuleringar att kontinuerliga observationssekvenser på upp till 48 minuter kan förväntas varje månvarv. Variationen hos de optiska egenskaperna för månen under ett tillfälle är relaterad till orienteringen av rymdfarkostens plan i förhållande till konen med axeln för månen-solens riktning. Att välja ett värde för fasvinkeln (Sun-Moon-Spacecraft-vinkel) på runt −20 grader vid planering av månkalibreringarna gör det möjligt att minimera variationerna i månens strålning under observationen. Resultaten gör det möjligt att förfina valet av de bästa tidpunkterna för månkalibreringarna. Detta gör det också möjligt för satellitoperationsteamet att förutse planeringen av månkalibreringar flera månader framåt.