54 research outputs found
Autonomous Navigation of Distributed Spacecraft using Graph-based SLAM for Proximity Operations in Small Celestial Bodies
Establishment of a sustainable human presence beyond the cislunar space is a major milestone for mankind. Small celestial bodies (SCBs) like asteroids are known to contain valuable natural resources necessary for the development of space assets essential to the accomplishment of this goal. Consequently, future robotic spacecraft missions to SCBs are envisioned with the objective of commercial in-situ resource utilization (ISRU). In mission design, there is also an increasing interest in the utilization of the distributed spacecraft, to benefit from specialization and redundancy. The ability of distributed spacecraft to navigate autonomously in the proximity of a SCB is indispensable for the successful realization of ISRU mission objectives. Quasi-autonomous methods currently used for proximity navigation require extensive ground support for mapping and model development, which can be an impediment for large scale multi-spacecraft ISRU missions in the future.
It is prudent to leverage the advances in terrestrial robotic navigation to investigate the development of novel methods for autonomous navigation of spacecraft. The primary objective of the work presented in this thesis is to evaluate the feasibility and investigate the development of methods based on graph-based simultaneous localization and mapping (SLAM), a popular algorithm used in terrestrial autonomous navigation, for the autonomous navigation of distributed spacecraft in the proximity of SCBs. To this end, recent research in graph-based SLAM is extensively studied to identify strategies used to enable multi-agent navigation. The spacecraft navigation requirement is formulated as a graph-based SLAM problem using metric GraphSLAM or topometric graph-based SLAM. Techniques developed based on the identified strategies namely, map merging, inter-spacecraft measurements and relative localization are then applied to this formulation to enable distributed spacecraft navigation. In each case, navigation is formulated in terms of its application to a proximity operation scenario that best suits the multi-agent navigation technique.
Several challenges related to the application of graph-based SLAM for spacecraft navigation, such as computational cost and illumination variation are also identified and addressed in the development of these methods. Experiments are performed using simulated models of asteroids and spacecraft dynamics, comparing the estimated states of the spacecraft and landmarks to the assumed true states. The results from the experiments indicate a consistent and robust state determination process, suggesting the suitability of the application of multi-agent navigation techniques to graph-based SLAM for enabling the autonomous navigation of distributed spacecraft near SCBs
Our Mythical Hope
Classical Antiquity is a particularly important field in terms of “Hope studies” […]. For centuries, the ancient tradition, and classical mythology in particular, has been a common reference point for whole hosts of creators of culture, across many parts of the world, and with the new media and globalization only increasing its impact. Thus, in our research at this stage, we have decided to study how the authors of literary and audiovisual texts for youth make use of the ancient myths to support their young protagonists (and readers or viewers) in crucial moments of their existence, on their road into adulthood, and in those dark hours when it seems that life is about to shatter and fade away. However, if Hope is summoned in time, the crisis can be overcome and the protagonist grows stronger, with a powerful uplifting message for the public. […] Owing to this, we get a chance to remain true to our ideas, to keep faith in our dreams, and, when the decisive moment comes, to choose not hatred but love, not darkness but light.
Katarzyna Marciniak, University of Warsaw, From the introductory chapte
Exploring the dynamics of knowledge sharing in the online affinity apaces of "Let's Play" Youtube Channels
With this dissertation the goal is to analyze the novel medium of video game streaming and more specifically the “Let’s Play” video format as seen on YouTube and other online platforms. The practice has experienced a rapid growth in popularity over the course of the last decade since its emergence, which means many of its intricacies are yet to be accounted for by academic research. The intent is to engage with it from the perspective of learning and knowledge exchange and see whether such processes take place within the channels dedicated to this type of content, and if so to map out their dynamics, and reflect critically on the picture that emerges from the exploration of these virtual spaces.El objetivo de esta tesis es analizar el nuevo medio para retransmisión de videojuegos y, en particular, el formato de vídeo "Let's Play" como el que está en YouTube y otras plataformas en línea. La práctica ha experimentado un rápido crecimiento de popularidad en el transcurso de la última década desde su aparición, lo que significa que muchas de sus complejidades aún deben tenerse en cuenta por la investigación académica. La intención es abordar este formato desde la perspectiva del aprendizaje y el intercambio de conocimientos y ver si tales procesos tienen lugar dentro de los canales dedicados a este tipo de contenido y, en caso de ser así, trazar la dinámica y reflexionar críticamente sobre el panorama que surge de la exploración de estos espacios virtuales.L'objectiu d'aquesta tesi és analitzar el nou mitjà de retransmissió de videojocs i, més concretament, el format de vídeo "Let's Play" que es veu a YouTube i altres plataformes en línia. La popularitat d'aquesta pràctica ha crescut ràpidament durant l'última dècada des de la seva aparició, cosa que significa que moltes de les seves complexitats encara no han estat considerades per la investigació acadèmica. La intenció és abordar-lo des de la perspectiva de l'aprenentatge i l'intercanvi de coneixements i veure si aquests processos es desenvolupen dins dels canals dedicats a aquest tipus de continguts i, en cas afirmatiu, establir-ne la dinàmica i reflexionar de manera crítica sobre el panorama que es desprèn de l'exploració d'aquests espais virtuals
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Biomimetic models of visual navigation - active sensing for embodied intelligence
Insects have developed small scale search behaviours to pursue navigation relevant stimuli more effectively. These often resemble a variation of Zig-Zagging, steering periodically to the left and right, therefore increasing the sampling. In this context we investigate the role of a homologous insect brain structure, the Lateral Accessory Lobe (LAL), which has been described as a pre-motor centre but received limited attention so far. Following a synthesis of the literature on the LAL we developed a steering framework, which proposes that with lateralised stimuli as input, the LAL can initiate a Zig-Zagging behaviour if the input is too weak, meaning unreliable, and targeted steering behaviours if the input is strong, thus reliable. Based on this framework we model a Spiking Neural Network (SNN) investigating a sensory modulated Central Pattern Generator (CPG) as a possible neural mechanism enabling adaptive search behaviours. We investigated the parameter space of the model to discover both the range of possible behaviours as well as which parameter combinations lead to the previously described behaviour. We found that no parameter combination accounts for the majority of observed behaviours. Furthermore, changing the computational noise levels does not lead to break-down of this behaviour. We conclude, that this neural architecture is robust to generate an adaptable Zig-Zagging behaviour. Additionally, we developed a more comprehensive network to explore the functions of known neuron-types with regard to motor control. To investigate how this steering framework might work for view based navigation, we investigated how lateralised sensory input can be used for snapshot navigation. We used a 3D-reconstruction from a LiDAR-scanned field-site (“Antworld”) to generate realistic visual stimuli. Instead of using the entire panorama, we subdivided this into two Fields of View for snapshot generation and the later image comparisons. The difference of image familiarity from both sides was subtracted to initiate a steering response into the most familiar direction. We found that a bigger Field of View alongside non-forward facing memories generated the most correct steering responses towards the snapshot direction. This demonstrates that the LAL-inspired steering framework can be functional for a complex sensori-motor task that had previously not been implicated in LAL functionality. Finally, we modelled how bilateral sensory information and a SNN model of the LAL behave in a snapshot navigation setup using Antworld. We compared the original snapshot navigation model using a panoramic Field of View with several combinations of the Core-Network and bilateral vision models: using a bilateral view, a bilateral view with the SNN, a panoramic view with SNN and other standard movement behaviours. We confirmed the findings of preliminary work, in an abstract setup, that had shown that a bilateral view combined with a SNN performs best to recover and approach navigation relevant locations. Also introducing models based on the steering framework into this visually complex environment improved the performance of agents performing snapshot navigation
Aerial Vehicles
This book contains 35 chapters written by experts in developing techniques for making aerial vehicles more intelligent, more reliable, more flexible in use, and safer in operation.It will also serve as an inspiration for further improvement of the design and application of aeral vehicles. The advanced techniques and research described here may also be applicable to other high-tech areas such as robotics, avionics, vetronics, and space
MEANS OF CONVEYANCE: SPOKEN WORD PEDAGOGY, HIP HOP LITERACIES, AND THE CHALLENGES OF FOSTERING POETRY SPACES
Thesis (Ph.D.) - Indiana University, School of Education, 2020This dissertation examined the relationships between teachers, students, and “teaching artists” (Graham, 2009) who use poetry as a vehicle for literacy learning. One popular practice is the use of “spoken word,” (Somers-Willett, 2009) a fiery brand of performative poetry popularized by artists from the hip hop music scene (Hill, 2009) and the competitive poetry slam circuit (Woods, 2008). A wealth of qualitative studies extol the virtues of “spoken word pedagogy,” (Kim, 2013; Low, 2011; Weinstein, 2010) noting its power when used as a vehicle for writers to construct literate identities (Fisher, 2007) and form critiques of socio-political issues (Jocson, 2008). To best understand how these dialogic communities operate in precarious times, this study explored the numerous, overlapping spaces where spoken word is used as a pedagogy for multiliteracies. This dissertation employed a practice that Prendergast (2009) called “poetic inquiry,” a creative approach to qualitative inquiry where the researcher adopts the tools a poet uses to search for truth in the world. To explore critical issues in the global spoken word community, a new, hip-hop-infused version of poetic inquiry was created for this study, called “(re)mixed methods.” The findings of this four year study reveal that collaborative teams of poets often face concrete challenges sustaining educational poetry programs, which threaten the relationships necessary to hearten such communities. Findings also highlight that many participants use poetry to name these barriers that repress them, authoring striking narratives about issues such as economic inequality, the need for school reform, structural racism, gender discrimination, the school-to-prison pipeline, and the unmet mental health needs of students. The implications of these findings challenge stakeholders to consider how spoken word pedagogy ix serves as a conduit for intergenerational dialogue, and could be used to help collaborative learning communities envision a future beyond the challenges they face
The Effects of Landscape and Experience on the Navigation and Foraging Behaviour of Bumblebees, Bombus terrestris
Bumblebees live in an environment where the spatial distribution of foraging resources is always changing. In order to keep track of such changes, bumblebees employ a variety of different navigation and foraging strategies. Although a substantial amount of research has investigated the different navigation and foraging behaviours of bumblebees, much less is known of the effects that landscape features have on bumblebee behaviour. In this thesis, a series of experiments were conducted in order to investigate the role that landscape features have on the navigation and foraging behaviour of Bombus terrestris and whether individuals’ experience influences such behaviour. A hedgerow situated next to the colony was not found to significantly shape the flight paths or foraging choices of naïve bumblebees. Homing success was investigated and used as a proxy for foraging range in different environment types. Both the release distance and the type of environment were found to have a significant effect on the homing success of Bombus terrestris workers. Previous experience of the landscape was also found to significantly affect the time it took bumblebees to return to the colony (homing duration) as well as the likelihood of staying out overnight before returning to the colony. When focusing on the first five flights of a naïve bumblebee worker, experience was not found to significantly affect flight duration. Experience, however, significantly affected the weight of pollen foraged. The observed behaviour of bumblebee gynes provisioning their maternal colony with pollen was also investigated. The influx of pollen into the colony was found to affect this behaviour, suggesting that gynes will provision the maternal colony in response to its nutritional needs. The overall results are also discussed within the context of informing landscape management practices. The results presented in this thesis point to the critical role that factors such as the physical landscape and individual experience play in influencing bumblebee behaviour.South Devon Area of Outstanding Natural Beauty (AONB) Uni
Autonomous Navigation for Mars Exploration
The autonomous navigation technology uses the multiple sensors to percept and estimate the spatial locations of the aerospace prober or the Mars rover and to guide their motions in the orbit or the Mars surface. In this chapter, the autonomous navigation methods for the Mars exploration are reviewed. First, the current development status of the autonomous navigation technology is summarized. The popular autonomous navigation methods, such as the inertial navigation, the celestial navigation, the visual navigation, and the integrated navigation, are introduced. Second, the application of the autonomous navigation technology for the Mars exploration is presented. The corresponding issues in the Entry Descent and Landing (EDL) phase and the Mars surface roving phase are mainly discussed. Third, some challenges and development trends of the autonomous navigation technology are also addressed
Lunar Crater Identification in Digital Images
It is often necessary to identify a pattern of observed craters in a single
image of the lunar surface and without any prior knowledge of the camera's
location. This so-called "lost-in-space" crater identification problem is
common in both crater-based terrain relative navigation (TRN) and in automatic
registration of scientific imagery. Past work on crater identification has
largely been based on heuristic schemes, with poor performance outside of a
narrowly defined operating regime (e.g., nadir pointing images, small search
areas). This work provides the first mathematically rigorous treatment of the
general crater identification problem. It is shown when it is (and when it is
not) possible to recognize a pattern of elliptical crater rims in an image
formed by perspective projection. For the cases when it is possible to
recognize a pattern, descriptors are developed using invariant theory that
provably capture all of the viewpoint invariant information. These descriptors
may be pre-computed for known crater patterns and placed in a searchable index
for fast recognition. New techniques are also developed for computing pose from
crater rim observations and for evaluating crater rim correspondences. These
techniques are demonstrated on both synthetic and real images
Peripheral visions: you would not want to be staring like that at me: the American other and the carnival spectacle in HBO’s True Blood, Deadwood and Carnivàle, & a novel, Tarnished
‘You would not want to be staring like that at me.’ The minacious words of Deadwood’s Al Swearengen ring out beyond the show’s Wild West confines and speak to the wider cultural anatomy of the United States. Swearengen is threatening his nemesis, Sheriff Bullock, who has decided to communicate his contempt for Swearengen with one, long look. Al returns this glare, his verbal riposte a mere addendum to their power struggle that is, in that moment, reaching its climactic end through a distinctly visual discourse.
The visual, what we look like, what we look at and how we look at each other, the superficial dermal sign and what it signifies, not only about itself but about the viewer also, permeates and produces American subcultural interactions. Philip McGowan calls this ‘an economy of seeing’, and conceives it as a distinctly American version of the Carnivalesque that renders the act of looking a method of both highlighting and monetising difference and negating the different, of constructing and deconstructing the identities of those who do not fit into the template of the norm (white, able-bodied), and of creating a binary between this norm and an American ‘Other’, the racial, physiological, cultural outsider. McGowan traces the development of restrictive visual exchange through the chronology of the American exposition, the midway and the freak show, arguing that these public events provided a model for the paying public on how to frame and interact with this ‘Other’ in both showground and more quotidian spaces. McGowan follows this historical precedent through to its literary permutations, exploring texts that best illustrate his conceptual reframing of the Carnivalesque in distinctly American terms.
I seek to take this updated framework and apply it to its other natural counterpart, serial television (HBO specifically), the filmic, opt-in, long-form narratives that have overtaken cinema as both our premier visual product and primary means of replicating, investigating and evaluating culture. The shows I have selected (True Blood, Deadwood and Carnivàle) each stand as and offer up instances of these visual behaviours through their narratives and aesthetics, depicting this normal/’Other’ binary in illuminative, intersectional and often disruptive ways.
With these concerns in mind, I also present my own creative work, a novel that attempts to converge American Gothic and Western tropes (succeeding other less explicitly coalesced examples) in order to more fully materialise the inherent potential of this specific hybrid, and that was, in part, written in consideration of and as response to this critical discourse and its associated visual, cultural and historical cues
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