Currently, the concept of multipurpose spacecrafts is being transformed into many small spacecrafts each of them performing specific tasks and thus leading to the realization of pico and nano satellites. No matter what is the application or size, demand for more number of IR channels for earth observation is ever increasing which necessitates significant reduction in the mass, power requirement and cost of the IR detectors. In this scenario, several order of magnitude mass and power savings associated with uncooled IR arrays are advantageous compared to cooled photon detectors. However the poor speed of response of uncooled microbolometer array devices obstruct the total replacement of cooled detectors in thermal imaging applications. This is especially true when the mission requires 50 m to 100 m ground resolution, in which even the "fastest" micro bolometer arrays turns "too slow" to follow the ground trace when looked from low earth orbit (LEO). Hence there is a great and unfulfilled requirement of faster uncooled detector arrays for meeting the demand for future micro and mini satellite projects for advanced missions. The present thesis describes the systematic studies carried out in development of high performance IR and THz detectors for space applications. Ge-Si-O thin films are prepared by ion beam sputtering technique with argon (Ar) alone and argon and oxygen as sputtering species, using sputtering targets of different compositions of Ge and SiO2. The deposited thin films are amorphous in nature and have chemical compositions close to that of the target. The study of electrical properties has shown that the activation energy and hence the thermistor constant (β) and electrical resistivity (ρ) are sensitive to oxygen flow rate, and they are the least for thin films prepared with Ar alone as the sputtering species. Different thermal isolation structures (TIS), consisting of silicon nitride (Si3N4) membrane of different thicknesses, Ge-Si-O thin film and, chromium coating on the rear side of the membrane, are prepared by bulk micro-machining technique, whose thermal conductance (Gth) properties are evaluated from the experimentally determined current-voltage (I-V) characteristics. Gth shows non-linear dependence with respect to raise in temperature of thin film thermistor due to Joule heating. The infrared micro-bolometer detectors, fabricated using one of the TIS structures have shown responsivity (<v) close to 115 V W−1 at a bias voltage of 1.5 V and chopping frequency of 10 Hz, thermal time constant (τth) of 2.5 ms and noise voltage of 255 nV Hz−1⁄2 against the corresponding thermal properties of Gth and thermal capacitance Cth equal to 9.0 × 10−5 W K−1 and 1.95 × 10−7 J K−1 respectively. The detectors are found to have uniform spectral response in the infrared region from 2 µm to 20 µm, and NEDT in the range from 108 mK to 574 mK when used with an F/1 optical system. The detector, in an infrared earth sensor system, is tested before an extended black body which simulates the earth disc in the laboratory and the results are discussed. As an extension of the single element detector to array device, design of a microbolometer array for earth sensor dispensing of scanning mechanisms is presented. It makes use of four microbolometer arrays with in-line staggered configuration that stare at the earth horizons, perceiving IR radiation in the spectral band of 14 µm to 16 µm. Design of the microbolometer has been carried out keeping in mind low power, lightweight, without compromising on the performance. An array configuration of 16 × 2 pixels is designed and developed for this purpose. Finite elemental analysis is carried out for design optimization to yield best thermal properties and thus high performance of the detectors. Suitable optical design configuration was arrived to image the earth horizon on to array. Using this optimum design, prototype arrays have been fabricated, packaged and tested in front of the black body radiation source and found to have Responsivity, NEP, and D∗ of 120 V W−1, 5.0 W Hz−1⁄2, 1.10 × 107 cm Hz1⁄2 W−1 respectively. The pixels show a uniform response within a spread of ±6 % and the pixel resistances are within a range of ±5 %. Optically Immersed Bolometer IR detectors are fabricated using electron beam evaporated Vanadium Oxide as the sensing material. Spin coated polyimide is used as medium to optically immerse the sensing element to the flat surface of a hemispherical germanium lens. This optical immersion layer also serves as the thermal impedance control layer and decides the performance of the devices in terms of responsivity and noise parameters. The devices have been packaged in suitable electro-optical packages and the detector parameters are studied in detail. Thermal time constant varies from 0.57 ms to 6.1 ms and responsivity from 75VW−1 to 757VW−1 corresponding to polyimide thickness in the range 2.0 μm to 70 μm for a detector bias of 9V. Highest D obtained was 1.28 × 108 cm Hz1⁄2W−1. Noise Equivalent Temperature Difference (NETD) of 20mK is achieved for devices with polyimide thickness of 32 μm, whereas the NETD × th product is the lowest for devices with moderate thickness of thermal impedance layer. Bolometric THz detectors were fabricated using V2O5 as sensing element immersed onto germanium hemispherical lens using polyimide as immersion media. These detectors were characterized for their efficiency in detection of THz radiation in the range 10 THz to 35 THz emitted by a black body radiator. The responsivity of the devices determined in four different frequency bands covering the spectrum of interest and a maximum responsivity of 398VW−1 was observed. A variation in the responsivity is observed which is due to the characteristics absorption of polyimide in the THz region of interest and can be avoided by replacing with HDPE which has less attenuation. NEP of 6.8 × 10−10WHz−1⁄2 was observed which is very close to the state of art in the case of uncooled detectors which entitles the detectors for spectroscopic applications. Specific Detectivity D* was observed to be much higher than the conventional detectors thanks to the benefits of immersion. NETD of 26mK was observed which is advantageous of application of these detectors in imaging applications These studies have lead to development of a new technology for fabrication of high performance IR and THz detectors which can be used for spectroscopic and imaging applications. Further, this technology can be scaled for development of linear and area arrays finding applications where the speed of respnose as well as sensitivity are of equal importance. from 0.57 ms to 6.1 ms and responsivity from 75 V W−1 to 757 V W−1 corresponding to polyimide thickness in the range 2.0 µm to 70 µm for a detector bias of 9 V. Highest D∗ obtained was 1.28 × 108 cm Hz1⁄2 W−1. Noise Equivalent Temperature Difference (NETD) of 20 mK is achieved for devices with polyimide thickness of 32 µm, whereas the NETD × τth product is the lowest for devices with moderate thickness of thermal impedance layer. Bolometric THz detectors were fabricated using V2O5 as sensing element immersed onto germanium hemispherical lens using polyimide as immersion media. These detectors were characterized for their efficiency in detection of THz radiation in the range 10 THz to 35 THz emitted by a black body radiator. The responsivity of the devices determined in four different frequency bands covering the spectrum of interest and a maximum responsivity of 398 V W−1 was observed. A variation in the responsivity is observed which is due to the characteristics absorption of polyimide in the THz region of interest and can be avoided by replacing with HDPE which has less attenuation. NEP of 6.8 × 10−10 W Hz−1⁄2 was observed which is very close to the state of art in the case of uncooled detectors which entitles the detectors for spectroscopic applications. Specific Detectivity D* was observed to be much higher than the conventional detectors thanks to the benefits of immersion. NETD of 26 mK was observed which is advantageous of application of these detectors in imaging applications These studies have lead to development of a new technology for fabrication of high performance IR and THz detectors which can be used for spectroscopic and imaging applications. Further, this technology can be scaled for development of linear and area arrays finding applications where the speed of respnose as well as sensitivity are of equal importance.

La spectroscopie de bruit quasi-thermique est une méthode précise de déterminat-ion de la densité et de la température dans les plasmas spatiaux. Lorsqu'une antenne électrique est immergé dans un plasma, elle est capable de mesurer les fluctuations électrostatiques provoquées par le mouvement thermique des particules de plasma. Ces fluctuations sont détectées par la densité de puissance spectrale aux bornes de l'antenne, en observant un spectre à des fréquences comparables à la fréquence plasma électronique aussi bien pour les électrons que pour les protons, car le signal du proton est fortement décalé Doppler vers des fréquences plus élevées en raison de la vitesse de dérive du vent solaire. En plus d'induire le champ électrique fluctuant, une partie des électrons impactent sur la surface de l'antenne, ce qui provoque des perturbations de son potentiel électrique. Le signal provoqué par cette population est directement proportionnelle au flux d'électrons du plasma impactant l'antenne et est dominante si l'antenne a une grande surface. Dans ce travail, nous utilisons la théorie de l'orbite limite pour calculer le flux de particules impactantes pour un plasma non thermique décrit par fonction de distribution de vitesses $kappa$ ou Lorentzienne, communément mesurée dans le vent solaire. L'augmentation de la collecte de particules par des objets cylindriques et sphériques est quantifié et présenté en tant que fonction du potentiel électrostatique de surface et de la fraction des particules supra-thermique. La prise en compte de ces résultats théoriques est absolument nécessaire pour des mesures précises des paramètres du plasma à chaque fois que le bruit d'impact est l'élément dominant dans le spectre de puissance. Ceci est le cas pour STEREO, car les bruit d'impact est dominant pour cette sonde, en raison de la présence d'antennes courtes et épaisses. L'étude approfondie des données sur cette mission est motivée par le fait que ses analyseurs d'électrons sont défectueux depuis le lancement et aucune information sur les électrons thermiques n'est disponible. Les résultats obtenus sont vérifiés en comparant avec les résultats de Wind, montrant une bonne concordance entre les valeurs mesurées par les deux satellites. Les incertitudes des mesures sont déterminées par les incertitudes des instruments utilisés et sont estimés à environ $40%$. Le résultat final de ce travail sera l'établissement d'une base de données des moments d'électrons pour les deux sondes STEREO A et B qui couvriront toute la durée de la mission. Dans une seconde partie de la thèse, nous utilisons l'approche cinétique pour étendre la théorie du bruit quasi-thermique à des plasmas où les collisions des électrons avec les neutres jouent un rôle dominant. Cette technique permet de mesurer la densité et la température des électrons, et aussi la fréquence des collisions en tant que paramètres indépendants. Ceci est obtenu sur une large gamme de fréquences aussi bien en dessous qu'au dessus de la fréquence plasma, pour peu que le rapport entre la fréquence de collision et fréquence de plasma ne soit pas inférieur à 0.1. Les résultats présentés ici peuvent potentiellement être appliqués avec succès dans les plasmas de laboratoire et ionosphères non magnétisés, tandis que pour l'ionosphère de la Terre leur utilisation est limitée aux fréquences basses à cause de la présence d'un champ magnétique fort. / The quasi-thermal noise spectroscopy is an accurate method of determination of density and temperature in space plasmas. When an electric antenna is immersed into a plasma, it is able to measure electrostatic fluctuations caused by the thermal motion of plasma particles. These fluctuations are detected as the power spectral density at the antenna terminals, observing a spectrum at frequencies comparable to the electron plasma frequency for both electrons and protons, since the proton signal is strongly Doppler-shifted towards higher frequencies due to the solar wind drift velocity. Beside inducing the fluctuating electric field, some of the electrons are impacting the antenna surface, causing disturbances of the antenna electric potential. The signal caused by this population is directly proportional to the flux of plasma electrons impacting the antenna and is dominant if the antenna has a large surface area. In this work, we use the orbit limited theory to calculate the incoming particle flux for a non-thermal plasma described by $kappa$ velocity distribution function, commonly measured in the solar wind. The increase in the particle collection by cylindrical and spherical objects is quantified and presented as a function of the surface electrostatic potential and the fraction of supra-thermal particles. Including these results into the theory has turned out to be absolutely necessary for accurate measurements of the plasma parameters whenever the shot noise is the dominant component in the power spectrum. This is the case for STEREO because the impact noise is overwhelming on this probe, due to the presence of short and thick antennas. The comprehensive study of data on this mission is motivated by the fact that the electron analyzers are malfunctioning since launch and no information on thermal electrons is available. Results obtained are verified by comparing with the results from Wind, showing a good match between the values measured by the two spacecraft. Uncertainties of the measurements are determined by the uncertainties of the instruments used and are estimated to be around $40%$. The final outcome of this work will be establishing a database of the electron moments in both STEREO A and B that will be covering the entire duration of the mission. In the second part of the thesis, we use the kinetic approach to expand the theory of the quasi-thermal noise to plasmas where electron-neutral collisions play a dominant role. This technique is able to measure the electron density, temperature and the collision frequency as independent parameters using the wide frequency range both below and above the plasma frequency, if the ratio of the collisional to plasma frequency is not smaller than 0.1. The results presented here have can be potentially applied in laboratory plasmas and unmagnetized ionospheres, while at the ionosphere of Earth their use is limited to low frequencies due to the presence of the magnetic field.

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<div>There is an increasing interest in future space missions devoted to the exploration of key moons in the Solar system. These many different missions may involve libration point orbits as well as trajectories that satisfy different endgames in the vicinities of the moons. To this end, an efficient design strategy to produce low-energy transfers between the vicinities of adjacent moons of a planetary system is introduced that leverages the dynamics in these multi-body systems. Such a design strategy is denoted as the moon-to-moon analytical transfer (MMAT) method. It consists of a general methodology for transfer design between the vicinities of the moons in any given system within the context of the circular restricted three-body problem, useful regardless of the orbital planes in which the moons reside. A simplified model enables analytical constraints to efficiently determine the feasibility of a transfer between two different moons moving in the vicinity of a common planet. Subsequently, the strategy builds moon-to-moon transfers based on invariant manifold and transit orbits exploiting some analytical techniques. The strategy is applicable for direct as well as indirect transfers that satisfy the analytical constraints. The transition of the transfers into higher-fidelity ephemeris models confirms the validity of the MMAT method as a fast tool to provide possible transfer options between two consecutive moons. </div><div> </div><div>The current work includes sample applications of transfers between different orbits and planetary systems. The method is efficient and identifies optimal solutions. However, for certain orbital geometries, the direct transfer cannot be constructed because the invariant manifolds do not intersect (due to their mutual inclination, distance, and/or orbital phase). To overcome this difficulty, specific strategies are proposed that introduce intermediate Keplerian arcs and additional impulsive maneuvers to bridge the gaps between trajectories that connect any two moons. The updated techniques are based on the same analytical methods as the original MMAT concept. Therefore, they preserve the optimality of the previous methodology. The basic strategy and the significant additions are demonstrated through a number of applications for transfer scenarios of different types in the Galilean, Uranian, Saturnian and Martian systems. Results are compared with the traditional Lambert arcs. The propellant and time-performance for the transfers are also illustrated and discussed. As far as the exploration of Phobos and Deimos is concerned, a specific design framework that generates transfer trajectories between the Martian moons while leveraging resonant orbits is also introduced. Mars-Deimos resonant orbits that offer repeated flybys of Deimos and arrive at Mars-Phobos libration point orbits are investigated, and a nominal mission scenario with transfer trajectories connecting the two is presented. The MMAT method is used to select the appropriate resonant orbits, and the associated impulsive transfer costs are analyzed. The trajectory concepts are also validated in a higher-fidelity ephemeris model.</div><div> </div><div>Finally, an efficient and general design strategy for transfers between planetary moons that fulfill specific requirements is also included. In particular, the strategy leverages Finite-Time Lyapunov Exponent (FTLE) maps within the context of the MMAT scheme. Incorporating these two techniques enables direct transfers between moons that offer a wide variety of trajectory patterns and endgames designed in the circular restricted three-body problem, such as temporary captures, transits, takeoffs and landings. The technique is applicable to several mission scenarios. Additionally, an efficient strategy that aids in the design of tour missions that involve impulsive transfers between three moons located in their true orbital planes is also included. The result is a computationally efficient technique that allows three-moon tours designed within the context of the circular restricted three-body problem. The method is demonstrated for a Ganymede->Europa->Io tour.</div>

Hold down release mechanisms (HDRMs) are used for tightly attaching segments of bodies together when it is desired to release them rapidly at some point. When transporting sensitive payloads on launch vehicles, the challenge arises of releasing the fastened segments of the spacecraft without risking damage to the costly equipment. Non-explosive HDRMs are favourable from a safety perspective as there is a lower risk of producing potentially destructive shock-waves throughout the structure.  One variant of a non-explosive HDRM uses a so called 'split spool initiator'. This initiator can only be used once in the actuator mechanism and to reuse the HDRM the initiator must be replaced. The purpose of this thesis is to design an improved split spool initiator which can be reusable while conserving the functionality aspects of the existing design. To achieve this, different ideas were considered and ultimately a solution using shape memory alloys (SMAs) was explored. A prototype was constructed to demonstrate the functionality of the design and simulations are done to determine the forces acting on different parts of the mechanism. / Hold down release-mekanismer (HDRM) används för att säkert kunna fästa samman delar av strukturer för att sedan kunna lossa dessa vid rätt tillfälle. När det transporteras känslig last på exempelvis rymdfarkoster uppkommer utmaningen att göra så på ett sätt som inte riskerar att skada den ofta dyra utrustningen. Det finns en mängd olika HDRM, dessa kan delas upp i två typer som är icke explosiva release-mekanismer och pyrotekniska release-mekanismer. Icke explosiva release-mekanismer har en fördel över pyrotekniska som är att de inte producerar potentiellt destruktiva chock-vågor som sprids genom strukturen. En typ av icke-explosiva release-mekanismer är den så kallade split spool-initieraren. Denna kan endast användas en gång när fästelementet är aktiverat och för att kunna använda fästelementet igen måste hela initieraren bytas ut. Syftet med denna studie har varit att att designa en förbättrad split spool-initierare som är återanvändbar, medan funktionaliteten hos den ursprungliga designen är bevarad. För att åstadkomma detta övervägdes olika idéer och slutligen valdes en lösning som använder minnesmetaller eller Shape memory alloys på engelska (SMA). En prototyp konstruerades för att demonstrera funktionaliteten hos designen. Simuleringar gjordes även för att bestämma krafter som agerade på split spool-strukturen och för att få en överblick över spänningsfördelningen genom initieraren.

For the transport of their spacecraft from the vehicle assembly building to the launch pads at Kennedy Space Centre, Florida, the National Aeronautics and Space Administration (NASA) is using two special crawler transporters since 1965. First developed for the Saturn V rocket the crawler transporters have been sufficient for all following generations of space ships so far. But for the new generation of Orionspacecraft which is under development now, a load capacity increase for the crawler transporter of plus 50% was necessary. For this task Hunger Hydraulik did develop new jacking, equalizing and levelling (JEL) cylinders with sufficient load capacity but also with some new features to improve the availability, reliability and safety of this system. After design approval and manufacture of the cylinders they have been tested in a special developed one-to-one scale dynamic test rig and after passing this the cylinders had to prove their performance in the crawler transporter itself. This article describes the general application and introduces the technical requirements of this project as well as the realized solution.

<p> </p> <p>In the coming decades, numerous missions plan to exploit multi-body orbits for operations. Given the complex nature of multi-body systems, trajectory designers must possess effective tools that leverage aspects of the dynamical environment to streamline the design process and enable these missions. In this investigation, a particular class of dynamical structures, quasi-periodic orbits, are examined. This work summarizes a computational framework to construct quasi-periodic orbits and a design framework to leverage quasi-periodic motion within the path planning process. First, quasi-periodic orbit computation in the Circular Restricted Three-Body Problem (CR3BP) and the Bicircular Restricted Four-Body Problem (BCR4BP) is summarized. The CR3BP and BCR4BP serve as preliminary models to capture fundamental motion that is leveraged for end-to-end designs. Additionally, the relationship between the Earth-Moon CR3BP and the BCR4BP is explored to provide insight into the effect of solar acceleration on multi-body structures in the lunar vicinity. Characterization of families of quasi-periodic orbits in the CR3BP and BCR4BP is also summarized. Families of quasi-periodic orbits prove to be particularly insightful in the BCR4BP, where periodic orbits only exist as isolated solutions. Computation of three-dimensional quasi-periodic tori is also summarized to demonstrate the extensibility of the computational framework to higher-dimensional quasi-periodic orbits. Lastly, a design framework to incorporate quasi-periodic orbits into the trajectory design process is demonstrated through a series of applications. First, several applications were examined for transfer design in the vicinity of the Moon. The first application leverages a single quasi-periodic trajectory arc as an initial guess to transfer between two periodic orbits. Next, several quasi-periodic arcs are leveraged to construct transfer between a planar periodic orbit and a spatial periodic orbit. Lastly, transfers between two quasi-periodic orbits are demonstrated by leveraging heteroclinic connections between orbits at the same energy. These transfer applications are all constructed in the CR3BP and validated in a higher-fidelity ephemeris model to ensure the geometry persists. Applications to ballistic lunar transfers are also constructed by leveraging quasi-periodic motion in the BCR4BP. Stable manifold trajectories of four-body quasi-periodic orbits supply an initial guess to generate families of ballistic lunar transfers to a single quasi-periodic orbit. Poincare mapping techniques are used to isolate transfer solutions that possess a low time of flight or an outbound lunar flyby. Additionally, impulsive maneuvers are introduced to expand the solution space. This strategy is extended to additional orbits in a single family to demonstrate "corridors" of transfers exist to reach a type of destination motion. To ensure these transfers exist in a higher fidelity model, several solutions are transitioned to a Sun-Earth-Moon ephemeris model using a differential corrections process to show that the geometries persist.</p>

Proper modelling of the gravitational fields of irregularly shaped asteroids and comets is an essential yet challenging part of any spacecraft visit and flyby to these bodies. Accurate density representations provide crucial information for proximity missions, which rely heavily on it to design safe and efficient trajectories. This work explores using a spacecraft swarm to maximise the measured gravitational signal in a hypothetical mission around the comet 67P/Churyumov-Gerasimenko. Spacecraft trajectories are simultaneously computed and evaluated using a high-order numerical integrator and an evolutionary optimisation method to maximise overall signal return. The propagation is based on an open-source polyhedral gravity model using a detailed mesh of 67P/C-G and considers the comet’s sidereal rotation. We compare performance on various mission scenarios using one and four spacecraft. The results show that the swarm achieved an expected increase in coverage over a single spacecraft when considering a fixed mission duration. However, optimising for a single spacecraft results in a more effective trajectory. The impact of dimensionality is further studied by introducing an iterative local search strategy, resulting in a generally improved robustness for finding efficient solutions. Overall, this work serves as a testbed for designing a set of trajectories in particularly complex gravitational environments, balancing measured signals and risks in a swarm scenario. / En korrekt modellering av de gravitationsfält som uppstår runt irreguljärt formade asteroider och kometer är en avgörande och utmanande del för alla uppdrag till likartade himlakroppar. Exakta densitetsrepresentationer tillhandahåller viktig information för att säkerställa säkra och effektiva rutter för särsilt närgående rymdfarkoster. I denna studie utforskar vi användningen av en svärm av rymdfarkoster för att maximera den uppmätta gravitationssignalen i ett hypotetisk uppdrag runt kometen 67P/Churyumov-Gerasimenko. Rymdfarkosternas banor beräknas och utvärderas i parallella scheman med hjälp av en högre ordningens numerisk integration och en evolutionär optimeringsmetod i syfte att maximera den totala uppmätta signalen. Beräkningarna baseras på en öppen källkod för en polyhedral gravitationsmodell som använder ett detaljerat rutnät av triangulära polygoner för att representera 67P/C-G och beaktar kometens egna rotation. Vi jämför sedan prestanden för olika uppdragscenarier med en respektive fyra rymdfarkoster. Resultaten visar att svärmen uppnådde en förväntad ökning i täckning jämfört med en enskild rymdfarkost under en fast uppdragsvaraktighet. Dock resulterar optimering för en enskild rymdfarkost i en mer effektiv bana. Påverkan av dimensionshöjningen hos oberoende variabler studeras vidare genom att introducera en iterativ lokal sökstrategi, vilket resulterar i en generellt förbättrad robusthet samt effektivare lösningar. Sammantaget fungerar detta arbete som en testbädd för att studera och utforma rymdfarkosters banor i särskilt komplexa gravitationsmiljöer, samt för att balansera uppmätta signaler och risker i ett svärmscenario.

Formation control in multi-agent systems represents a groundbreaking intersection of various research fields with lots of emerging applications in various technologies. The realm of space exploration also can benefit significantly from formation control, facilitating a wide range of functions from astronomical observations, and climate monitoring to enhancing telecommunications, and on-orbit servicing and assembly. In this thesis, we present a novel 3D formation control scheme for directed graphs in a leader-follower configuration, achieving (almost) global convergence to the desired shape. Specifically, we introduce three controlled variables representing bispherical coordinates that uniquely describe the formation in 3D. Acyclic triangulated directed graphs (a class of minimally acyclic persistent graphs) are used to model the inter-agent sensing topology, while the agents’ dynamics are governed by the single-integrator model and 2nd order nonlinear version representing spacecraft formation flight. The analysis demonstrates that the proposed decentralized robust formation controller using prescribed performance control ensures (almost) global asymptotic stability while avoiding potential shape ambiguities in the final formation. Furthermore, the control laws are implementable in arbitrarily oriented local coordinate frames of follower agents using only low-cost onboard vision sensors, making them suitable for practical applications. Formation maneuvering and collision avoidance among agents are also addressed which play crucial roles in the safety of space operations. Finally, we validate our formation control approach by simulation studies. / Formationskontroll i system med flera agenter representerar en banbrytande skärningspunkt av olika forskningsområden med massor av nya tillämpningar inom olika teknologier. Rymdutforskningens rike kan också dra stor nytta av formationskontroll, underlättar ett brett utbud av funktioner från astronomiska observationer och klimat övervakning för att förbättra telekommunikation och service och montering i omloppsbana. I denna avhandling presenterar vi ett nytt 3D-formationskontrollschema för riktade grafer i en ledare-följare-konfiguration, vilket uppnår (nästan) global konvergens till önskad form. Specifikt introducerar vi tre kontrollerade variabler som representerar bisfäriska koordinater som unikt beskriver formationen i 3D. Acykliska triangulerade riktade grafer (en klass av minimalt acykliska beständiga grafer) används för att modellera avkänningstopologin mellan agenter, medan agenternas dynamik styrs av singelintegratormodellen och 2:a ordningen olinjär version som representerar rymdfarkostbildningsflygning. Analysen visar att den föreslagna decentraliserade robusta formationskontrollanten använder föreskriven prestanda kontroll säkerställer (nästan) global asymptotisk stabilitet samtidigt som potentiell form undviks oklarheter i den slutliga formationen. Dessutom är kontrolllagarna implementerbara i godtyckligt orienterade lokala koordinatramar för efterföljare som endast använder lågkostnad ombord visionsensorer, vilket gör dem lämpliga för praktiska tillämpningar. Formationsmanövrering och undvikande av kollisioner mellan agenter tas också upp som spelar avgörande roller i säkerheten vid rymdoperationer. Slutligen validerar vi vår strategi för formningskontroll genom simuleringsstudier