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DESIGN OF LUNAR TRANSFER TRAJECTORIES FOR SECONDARY PAYLOAD MISSIONSAlexander Estes Hoffman (15354589) 27 April 2023 (has links)
<p>Secondary payloads have a rich and successful history of utilizing cheap rides to orbit to perform outstanding missions in Earth orbit, and more recently, in cislunar space and beyond. New launch vehicles, namely the Space Launch System (SLS), are increasing the science opportunity for rideshare class missions by providing regular service to the lunar vicinity. However, trajectory design in a multi-body regime brings a host of novel challenges, further exacerbated by constraints generated from the primary payload’s mission. Often, secondary payloads do not possess the fuel required to directly insert into lunar orbit and must instead perform a lunar flyby, traverse the Earth-Moon-Sun system, and later return to the lunar vicinity. This investigation develops a novel framework to construct low-cost, end-to-end lunar transfer trajectories for secondary payload missions. The proposed threephase approach provides unique insights into potential lunar transfer geometries. The phases consist of an arc from launch to initial perilune, an exterior transfer arc, and a lunar approach arc. The space of feasible transfers within each phase is determined through low-dimension grid searches and informed filtering techniques, while the problem of recombining the phases through differential corrections is kept tractable by reducing the dimensionality at each phase transition boundary. A sample mission demonstrates the trajectory design approach and example solutions are generated and discussed. Finally, alternate strategies are developed to both augment the analysis and for scenarios where the proposed three-phase technique does not deliver adequate solutions. The trajectory design methods described in this document are applicable to many upcoming secondary payload missions headed to lunar orbit, including spacecraft with only low-thrust, only high-thrust, or a combination of both. </p>
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Selected Trends and Space Technologies Expected to Shape the Next Decade of SSC ServicesAsk, Jacob January 2019 (has links)
Since the early 2000s the space industry has undergone significant changes such as the advent of reusable launch vehicles and an increase of commercial opportunities. This new space age is characterized by a dynamic entrepreneurial climate, lowered barriers to access space and the emergence of new markets. New business models are being developed by many actors and the merging of space and other sectors continues, facilitating innovative and disruptive opportunities. Already established companies are adapting in various ways as efforts to stay relevant are gaining attention. The previous pace of development that was exclusively determined by governmental programs are now largely set by private and commercial ventures. Relating to all trends, new technologies and driving forces in the space industry is no trivial matter. By analyzing and examining identified trends and technologies the author has attempted to discern those that will have a significant impact on the industrial environment during the next decade. Market assessments have been summarized and interviews have been carried out. Discussions and conclusions relating to the services provided by the Swedish Space Corporation are presented. This report is intended to update the reader on the current status of the space industry, introduce concepts and provide relevant commentary on many important trends. / Sedan början av 2000-talet har det skett markanta förändringar inom rymdindustrin, såsom utvecklingen av återanvändningsbara raketer och en ökad mängd kommersiella möjligheter. Denna nya rymder a karaktäriseras av ett dynamiskt klimat för entreprenörer, minskande barriärer för att etablera rymdverksamhet och uppkomsten av nya marknader. Nya affärsmodeller utvecklas och integrering mellan rymden och andra industrier fortsätter, vilket ger utrymme för utveckling av innovativa och disruptiva idéer. Redan etablerade företag anpassar sig till förändringarna på olika sätt och ansträngningar för att bibehålla relevans prioriteras. Utvecklingstakten inom branschen var tidigare dominerad av statliga program men är nu alltmer influerad av privata och kommersiella satsningar. Att relatera till ny teknik, nuvarande trender och drivkrafter inom rymdindustrin är Jacob Ask is pursuing a Master of Science degree in Aerospace Engineering at KTH Royal Institute of Technology in Stockholm, Sweden. Christer Fuglesang is a professor in Space Travel, director of KTH Space Center and responsible for the Aerospace Engineering master program. He serves as the examiner for this master thesis project. Linda Lyckman is the Head of Business & Technology Innovation at SSC and supervisor for this master thesis project. komplext. Genom att undersöka och analysera identifierade trender och teknologier ämnar författaren urskilja de som kan komma att påverka industrin i störst utsträckning under det kommande decenniet. Bedömningar av marknadsmöjligheter och intervjuer har genomförts och i denna rapport presenteras ¨aven diskussioner och slutsatser relaterade till den typ av tjänster som Swedish Space Corporation erbjuder. Denna rapport har för avsikt att uppdatera läsaren om delar av den aktuella nulägesanalysen inom rymdindustrin, introducera koncept och ge relevanta kommentarer om viktiga trender.
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Investigating The Effects Of 3-d Spatialized Auditory Cues On The Development Of Situation Awareness For TeamsMilham, Laura 01 January 2005 (has links)
This dissertation investigated the effects of spatialized auditory cues on the development of situation awareness for teams. Based on extant research, it was hypothesized that 3-D spatialized auditory cues can be utilized by teams to develop knowledge about team member location in addition to supporting the usage of team behaviors for developing and maintaining situation awareness. Accordingly, the study examined how situation awareness would be differentially influenced by varying the type of auditory cues incorporated into virtual environment (VE) team training scenarios within the context of a MOUT team task. In general, the results of this study provided partial support for the beneficial effects of 3-D audio cues in facilitating the development of situation awareness and reducing workload. Implications are discussed in the context of design guidance for VE training systems.
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Human-Multi-Drone Interaction in Search and Rescue Systems under High Cognitive WorkloadAhlskog, Johanna January 2024 (has links)
Unmanned Aerial Vehicles (UAV), often referred to as drones, have seen increased use in search and rescue (SAR) missions. Traditionally, these missions involve manual control of each drone for aerial surveillance. As UAV autonomy progresses, the next phase in drone technology consists of a shift to autonomous collaborative multi-drone operations, where drones function collectively in swarms. A significant challenge lies in designing user interfaces that can effectively support UAV pilots in their mission without an overload of information from each drone and of their surroundings. This thesis evaluates important human factors, such as situational awareness (SA) and cognitive workload, within complex search and rescue scenarios, with the goal of increasing trust in multi-drone systems through the design and testing of various components. Conducting these user studies aims to generate insights for the future design of multi-drone systems. Two prototypes were developed with a multi-drone user interface, and simulated a stressful search and rescue mission with high cognitive workload. In the second prototype, a heatmap guided UAV pilots based on the lost person model. The prototypes were tested in a conducted user study with experienced UAV pilots in different SAR organizations across Sweden. The results showed variability in SA while monitoring drone swarms, depending on user interface components and SA levels. The prototypes caused significant cognitive workload, slightly reduced in the heatmap-equipped prototype. Furthermore, there was a marginal increase in trust observed in the prototype with the heatmap. Notably, a lack of manual control raised challenges for the majority of participants and many desired features were suggested by participants. These early expert insights can serve as a starting point for future development of multi-drone systems. / The HERD project, supported by the Innovation Fund Denmark for the DIREC project (9142-00001B)
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Data-Driven Reachability Analysis of Pedestrians Using Behavior Modes : Reducing the Conservativeness in Data-Driven Pedestrian Predictions by Incorporating Their Behavior / Datadriven Nåbarhetsanalys av Fotgängare som Använder Beteendelägen : Reducerar Konservativiteten i Datadriven Fotgängarpredicering Genom att Integrera Deras BeteendeSöderlund, August January 2023 (has links)
Predicting the future state occupancies of pedestrians in urban scenarios is a challenging task, especially considering that conventional methods need an explicit model of the system, hence introducing data-driven reachability analysis. Data-driven reachability analysis uses data, inherently produced by an unknown system, to perform future state predictions using sets, generally represented by zonotopes. These predicted sets are generally more conservative than model-based reachable sets. Therefore, is it possible to cluster previously recorded trajectory data based on the expressed behavior and perform the predictions on each cluster to still be able to provide safety guarantees? The theory behind data-driven reachability analysis, which can handle input noise and model uncertainties and still provide safety guarantees, is quite recent. This means that previous implementations for predicting pedestrians are theoretically probabilistic and would not be appropriate to implement in actual systems. Thus, this thesis is not the first of its kind in predicting the future reachable sets for pedestrians using clustered behavioral data, but it is the first work that provides safety guarantees in the process. The method proposed in this thesis first labels the historically recorded trajectories into the behavior also referred to as mode, the pedestrian expressed, which is done by simple conditional statements. This is done offline. However, this implementation is designed to be modular enabling easier improvements to the labelling system. Then, the reachable sets are computed for each behavior separately, which enables a potential motion planner to decide on which modal sets are relevant for specific scenarios. Theoretically, this method provides safety guarantees. The outcomes of this method were more descriptive reachable sets, meaning that the predicted areas intersected areas that it reasonably should, and did not intersect areas it reasonably should not. Also, the volume of the zonotopes for the modal sets was observed to be smaller than the volume of the implemented baseline, indicating fewer over-approximations and less conservative predictions. These results enable more efficient path planning for Connected and Autonomous Vehicles (CAVs), thus reducing fuel consumption and brake wear. / Att predicera framtida tillstånd för fotgängare i urbana situationer är en utmaning, speciellt med tanke på att konventionella metoder behöver uttryckligen en modell av systemet, därav introduceringen av datadriven nåbarhetsanalys. Datadriven nåbarhetsanalys använder data, naturligt producerad av ett okänt system, för att genomföra framtida tillståndspredicering med hjälp av matematiska set, generellt representerade av zonotoper. Dessa predicerade sets är generellt sett mode konservativa än modellbaserade nåbara set. Därmed, är det möjligt att dela upp historiskt inspelade banor baserat på det uttryckta beteendet och genomföra prediceringar på varje kluster och bibehålla säkerhetsgarantier? Teorin bakom datadriven nåbarhetsanalys, som kan hantera brus i indatat och modellosäkerheter och bibehålla säkerhetsgarantier, är väldigt ny. Detta betyder att tidigare implementationer för att predicera fotgängare är, teoretiskt sett, probabilistiska och är inte lämpliga att implementera i riktiga system. Därmed, detta examensarbete är inte det första som predicerar framtida nåbara set för fotgängare genom att använda kluster för beteendedatat, men den är det första arbetet som bibehåller säkerhetsgarantier i processen. Den introducerade metoden i detta examensarbete rubricerar först de tidigare inspelade banorna baserat på beteendet, även kallat läget, som fotgängaren uttrycker, vilket är gjort genom simpla betingade påståenden. Detta görs offline. Dock, denna implementation är designad till att vara modulär vilket underlättar förbättringar till rubriceringssystemet. Fortsättningsvis, beräknas de nåbara seten för varje beteende separat, vilket möjliggör att en potentiell rörelseplanerare kan avgöra vilka beteendeset som är relevanta för specifika scenarion. Teoretiskt sett så ger denna metod säkerhetsgarantier. Resultaten från denna metod var först och främst mer beskrivande nåbara set, vilket betyder att de predicerade områdena korsar områden som de rimligtvis ska korsa, och inte korsar område som de rimligen inte ska korsa. Dessutom, volymen på zonotoperna for beteendeseten observerades att vara mindre än volymen för baslinjeseten, vilket indikerar lägre överskattningar och mindre konservativa prediceringar. Dessa resultat möjliggör mer effektiv rörelseplanering för uppkopplade och autonoma fordon, vilket reducerar bränsleförbrukningen och bromsslitage.
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Stretching and Restoring Directions as a Basis for Relative Trajectory DesignLorin Olivier Nugent (20371560) 17 December 2024 (has links)
<p dir="ltr">As traffic in cislunar space grows and missions become increasingly complex, effective understanding of relative motion between spacecraft is paramount. Additional tools are necessary to more accurately determine favorable relative behaviors in a multi-body gravitational environment. In this investigation, relative states are characterized as linear combinations of principal stretching and restoring directions to introduce techniques for relative trajectory design in the circular restricted three-body problem. These dynamically-informed directions form sets of orthonormal vector bases employed to describe and design spacecraft motion relative to a reference trajectory. Properties unique to 3x3 subsets of the state transition matrix are exploited to derive methodologies for two relative motion applications. First, the formulation is presented from a spacecraft loitering perspective, providing a framework to methodically determine ballistic relative trajectory options for visiting spacecraft. Secondly, modifications are introduced for flexible maneuver planning in a collision avoidance scenario. The two methodologies are assessed for a variety of test cases along four different periodic orbits in the Earth-Moon system.</p>
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ATTITUDE ESTIMATION USING LIGHT CURVESAlexander Burton (19233418) 29 July 2024 (has links)
<p dir="ltr">Tracking and characterizing the space debris population in Earth orbit is necessary to ensure that space can continue to be used safely. However, because space objects are affected by non-conservative forces like drag and solar radiation pressure, predicting the long-term evolution of their orbits is impossible without knowledge of their attitude profiles. Such knowledge may be unavailable for inactive satellites or objects of which the observer is not the owner or operator. In many cases, attitude cannot be measured directly because resolved images of space objects are unavailable due to the distance between the object and the observer, and the effects of atmospheric seeing. However, the total brightness of objects can still be measured. A set of brightness measurements over time is referred to as a "light curve.'' An object's observed brightness is influenced by its attitude and other factors such as its orbit, shape, and reflective properties. If some of these other factors are known, attitude information may be extracted from a light curve. Existing methods of solving this attitude inversion problem either require a good initial guess for an object's rotational states or do not provide a full state estimate. The work in this thesis avoids both problems and provides a full state estimate without requiring an initial state guess.</p><p><br></p><p dir="ltr">The attitude estimation process assumes that the observation geometry and the observed object's shape, reflection properties, and inertia tensor are known. In this thesis, an initial method of searching for attitudes that could correspond to each measurement using the viewing sphere is described. These possible attitudes or "pseudo-measurements'' are then used to initialize a probability hypothesis density filter that is theoretically capable of representing the multi-modal nature of the attitude estimate using a Gaussian mixture model. However, the probability hypothesis density filter is found to often diverge from the truth because it is necessary to merge and prune components of the Gaussian mixture model to avoid computational intractability. In its place, a particle swarm optimizer method for performing an attitude inversion has been developed. This method uses analytic attitude solutions to quickly propagate a large number of attitude time histories simultaneously. The particle swarm optimizer method is validated using simulated light curves for several objects. A preliminary attempt is made to estimate the attitude of an object using real light curve measurements.</p>
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Providing Situational Awareness For Naval Operators : Implementation of Two Prioritization AlgorithmsNilsson, Jonna, Lidh, Jesper January 2024 (has links)
On the 29th of August, the vessel Stena Scandica experienced a blackout. Before the blackout, 294 alarms were issued in 4 minutes. With the number of alarms, the operators could not prevent the blackout. The amount of information and the way it was presented became a hindrance to operators. They could not interpret their surroundings' information without fault from them. This interpretation is called situational awareness. This thesis will solve how information can be provided to operators without hindrance to situational awareness. The focus will be on the Swedish Navy's operators and their needs. The aim is to solve the problem by creating a system that provides situational awareness. The system will use the information on air- and seaborne targets from a radar and a camera display. Three research questions were proposed: how will the radar data structure be, how will it be ranked, and how will it be presented? The structure was expected to tell the targets' location, size, and movement. The ranking of the targets would tell if the targets were a threat to the naval operators. Lastly, the targets were expected to be presented with some of their information on a camera display. For the first question, the structure for both kinds of targets was constructed to meet the expectations. Two models were used to solve the second question. An artificial neural network and fuzzy c-means. The artificial neural network was chosen as it is one of the best classification algorithms. Fuzzy c-means were chosen since it can cluster similar behaviors together, therefore clustering high-threat targets together. Of these two models, the result showed that the artificial neural network was a better ranking method, with a higher accuracy of 92.9% for airborne targets and 80.6% for seaborne targets. A simulation was made to answer the third question and was built according to the expectations. The simulation only displayed the highest threat targets in the camera display. By presenting the high-threat targets, the operators received a better understanding of where the targets are in reality. In the future, studies should be conducted on implementation of the system on Swedish Navy vessels. For example, is there enough computational power for an artificial neural network? / Den 29 augusti drabbades fartyget Stena Scandica av ett strömavbrott. Innan strömavbrottet utlöste 294 larm inom 4 minuter, vilket gjorde det omöjligt för operatörerna att förhindra avbrottet. Mängden information och sättet den presenterades på blev ett hinder för operatörerna, vilket påverkade deras lägesbild. Arbete syftar till att lösa hur information kan tillhandahållas till operatörer utan att hindra deras situationsmedvetenhet, med fokus på den svenska marinens operatörer och deras behov. Detta arbete föreslår ett system som använder radardata och kameradisplayer för att tillhandahålla lägesbilden. Tre forskningsfrågor ställs: hur ska radarns datastruktur vara, hur ska den rankas, och hur ska den presenteras? Strukturen förväntas visa målens plats, storlek och rörelse. Rankningen ska indikera om målen utgör ett hot, och hög-hotmål ska presenteras på kameradisplayen. För att svara på den första frågan konstruerades strukturen för båda typerna av mål. För den andra frågan användes två modeller: ett artificiellt neuralt nätverk och fuzzy c-means. Det artificiella neurala nätverket visade sig vara den bästa metoden med en noggrannhet på 92,9% för luftmål och 80,6% för sjömål. En simulering gjordes för att svara på den tredje frågan, där endast de mest hotfulla målen visades på kameradisplayen. Detta gav operatörerna en bättre förståelse för var målen befann sig. Framtida studier bör undersöka systemets implementering på svenska marinens fartyg. Exempelvis om tillräcklig beräkningskraft finns för ett artificiellt neuralt nätverk.
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A computational approach to situation awareness and mental models in aviationMamessier, Sebastien 20 September 2013 (has links)
Although most modern, highly-computerized flight decks are known to be robust to small disturbances and failures, humans still play a crucial role in advanced decision making in off-nominal situations, and accidents still occur because of poor human-automation interaction.
In addition to the physical state of the environment, operators now have to extend their awareness to the state of the automated flight systems. To guarantee the accuracy of this knowledge, humans need to know the dynamics or approximate versions of the dynamics that rule the automation.
The operator's situation awareness can decline because of a deficient mental model of the aircraft and an excessive workload.
This work describes the creation of a computational human agent model simulating cognitive constructs such as situation awareness and mental models known to capture the symptoms of poor human-automation interaction and provide insight into more comprehensive metrics supporting the validation of automated systems in aviation.
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Obemannade sensorbärare i urban miljö : En komparativ studie mellan UAV och UGV för förband på stridsteknisk nivå / Unmanned sensor carriers in an urban environment : A comparative study between UAV and UGV for units on a tactical levelGustafsson, Andreas January 2018 (has links)
Den urbana miljön är en av de mest komplexa miljöer som svenska förband ska kunna strida i. Bristfällig information, tredimensionellt hot, korta stridsavstånd och civila är bara några av de utmaningar soldater ställs inför i urban miljö. Vissa av dessa utmaningar skulle kunna minskas genom nyttjande av obemannade sensorer, som skulle kunna ge chefer en tydligare lägesbild. Studien har genomförts som en komparativ fallstudie, där ett representativt flygande system har jämförts med ett markgående. Syftet med studien är att utröna vilket system har störst militär nytta. Utgångspunkt för jämförelsen är en konceptmodell för militär nytta, där systemen jämförts inom tre dimensioner; militär effektivitet, militär lämplighet samt ekonomisk överkomlighet. Utfallet av studien tyder på att det markgående systemet, UGV, har en något högre militär nytta än det flygande systemet. Vidare påvisar studien att det finns tydliga skillnader i kravuppfyllnad beroende på var och i vilken strid som systemen används. Det flygande har en tydlig fördel utanför byggnader under anfallsstrid, medan det markgående har en fördel inne i byggnader. Studien påvisar även att båda systemen bidrar med militär nytta till förband i urban miljö. / The urban environment is one of the most difficult environments that Swedish units are supposed to fight in. Inadequate information, a three-dimensional threat, close range combat and civilians are just a few of the challenges that face soldiers in urban environment. Some of these challenges could be reduced by the use of unmanned sensors, which could enhance the situational awareness. This study has been conducted as a comparative case study, where a representative aerial system has been compared with a ground system. The aim of the study is to determine which system has the highest military utility. The study is based on a concept model for military utility that has compared the systems within three dimensions; military effectiveness, military suitability and affordability. The result of the study indicates that the ground system, UGV, has a slight advantage in military utility compared to the aerial system. Further the study indicates that there are apparent differences between the systems depending on where they are used and in what combat situation. The aerial system has a clear advantage when used outside buildings and in offensive actions, whereas the ground system has an advantage inside buildings. The study also shows that both systems contributes with military utility to units in urban terrain.
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