Augmented reality (AR) systems are often used to superimpose virtual objects or information on a scene to improve situational awareness. Delays in the display system or inaccurate registration of objects destroy the sense of immersion a user experiences when using AR systems. AC electromagnetic trackers are ideally for these applications when combined with head orientation prediction to compensate for display system delays. Unfortunately, these trackers do not perform well in environments that contain conductive or ferrous materials due to magnetic field distortion without expensive calibration techniques. In our work we focus on both the prediction and distortion compensation aspects of this application, developing a “small footprint” predictive filter for display lag compensation and a simplified calibration system for AC magnetic trackers. In the first phase of our study we presented a novel method of tracking angular head velocity from quaternion orientation using an Extended Kalman Filter in both single model (DQEKF) and multiple model (MMDQ) implementations. In the second phase of our work we have developed a new method of mapping the magnetic field generated by the tracker without high precision measurement equipment. This method uses simple fixtures with multiple sensors in a rigid geometry to collect magnetic field data in the tracking volume. We have developed a new algorithm to process the collected data and generate a map of the magnetic field distortion that can be used to compensation distorted measurement data.

Attitude control is an essential subsystem of most spacecraft buses, therefore attitude determination plays a very important role as it is the feedback system for any closed-loop attitude control system. Of all attitude determination sensors star trackers are usually the most accurate ones. Unfortunately, the star trackers usually used on classical, large spacecrafts are too big, heavy and power hungry. For pico-satellites, which can only carry a limited amount of volume and mass and provide only limited power, these sensors obviously cannot be used. Consequently, miniaturized star trackers have been developed in recent years, but so far the available star trackers are not sufficiently miniaturized to be feasible for the use on pico-satellites, including STELLA, a miniaturized star tracker developed at the University of Würzburg. Therefore, further miniaturization is necessary, which is why the University of Würzburg is active on the research of star trackers for small satellites. A first prototype for a new star tracker for pico-satellites, called PicoStar, has been developed in the scope of this thesis. Using a simpler system design and new image sensors, its volume could be reduced by two-thirds and the mass by about half compared to STELLA. The expected performance is kept reasonably. There is still room for further reduction of the power consumption, as it is currently up to 30% higher than required. As this Master thesis focuses on the implementation of the embedded system and the optimization of the software of the star tracker, the prototype is not finalized. So far, the star tracker algorithm has been implemented and the attitude determination is running. First test results have shown that the next steps in the PicoStar development, among other things, have to be further calibration and testing. / Validerat; 20151109 (global_studentproject_submitter)

Depuis les tous premiers jours de l'ère spatiale, les satellites artificiels ont été considérés comme un outil pour la résolution de problèmes scientifiques et pratiques, notamment dans l'astronomie, l'observation de la Terre et les télécommunications. Traditionnellement, les gros satellites artificiels, avec une masse allant de plusieurs centaines de kilogrammes jusqu'à plusieurs tonnes, ont été utilisés pour ces besoins. Un élément clef pour permettre le succès de ces missions spatiales est un contrôle précis de l'attitude du satellite. Afin d'assurer la haute précision de pointage, un système de contrôle d'attitude et d'orbite (SCAO) repose sur les données fournies par un instrument optoélectronique appelé un senseur stellaire (ou Star Tracker, ST). L'utilisation des étoiles éloignées comme points de repère permet la détermination de l'attitude du satellite avec une précision de l'ordre de la seconde d'arc. Beaucoup de travaux sur la miniaturisation des sous-systèmes des satellites artificiels ont été entrepris au court des vingt dernières années. Cela a permis à l'industrie et aux passionnés de développer et construire des satellites de quelques kilogrammes pouvant accomplir de véritables missions spatiales. Centaines de ces satellites appelés « nano-satellites » sont lancé chaque année et certains parmi eux peut être considéré comme un replacement des gros satellites. Cependant, dû à de grosses contraintes de masse et de volume définis par les standards na no-satellites, tel que lU-3U CubeSat Design Specification, l'intégration de senseur stellaire dans ces nano-satellites n'était jusqu'à présent pas possible, limitant l'application de ces plateformes. Dans ce travail, senseur stellaire est considéré comme un système composé par un module caméra et un module de traitement d'image. les solutions possibles pour chaque module sont analysées séparément dans un contexte de miniaturisation de ST par modélisation et simulation. Elles sont ensuite évaluées ensemble comme les prototypes fonctionnels dans un installation hardware-in-the-loop (Hll). Cette recherche aborde plusieurs problèmes liés à la miniaturisation d'optique de caméra et du capteur d'image à pixel actif (active pixel sensor, APS), tels que la sensibilité réduite à la lumière des étoiles et l'incertitude de position des centroïdes à cause de la distorsions et l'aberrations chromatique d'optique miniaturisée. L'évaluation dans l'installation Hll se concentre autour des performances du module de traitement et plus particulièrement sur les performances du logiciel ST dans le mode d'opération « perdu dans l'espace» ("Iost-in-space", LIS). Une contribution originale de cette recherche est un algorithme de reconnaissance d'étoiles (StarID) nommé « RING-O » développé et breveté par l'auteur. Par rapport aux autres algorithmes existants, RING-O peut facilement être adapté et ajusté à différentes caméras et plateformes de traitement. Des implémentations logicielles d'algorithme ont été effectuées sur deux prototypes, l'un basé sur smartphone et l'autre basé sur une plateforme Xilinx Zynq, afin de réaliser une analyse des goulets et d'extraire les performances du système. Optimisé pour les plateformes multi-coeurs, RING-O garantit les délais d'acquisition initiale d'attitude comparable et souvent plus petits que les délais d'acquisition déclaré par les autres développeurs de senseur stellaires européens. / From the early days of the space age, satellites were considered as a solution for many scientific and practical tasks, notably astronomy, Earth observation and telecommunication. Traditionally and to the present day, mostly large satellites with a mass from several hundred kilograms to several tons are used for these purposes. The key success factor of such space missions is a fine control of satellite’s attitude. To ensure high pointing accuracy, satellite’s attitude determination and control subsystem (ADCS) relies on precise three-dimensional attitude data provided by an opto-electronic instrument called star tracker (ST). The use of stars as reference objects allows to determine the satellite’s attitude in real time with an arc-second precision.A significant work on miniaturization of satellite subsystems carried out in the past twenty years, allows us today to build a complete satellite with a mass of only a few kilograms. An increasing number of successful nano- and picosatellite missions demonstrates constantly improving capabilities of modern miniaturized satellite platforms. However, until recently, integration of a star tracker into a nanosatellite was not possible because of a large size of the device and relatively high power consumption, and that limited possible applications of the nanosatellites. In attempt to change the situation, in the last five years about a dozen of miniature star tracker prototypes, suitable for nanosatellite platforms, were proposed by various developers. Some were successfully tested in space, yet most prototypes, including the tiniest ones, are still at the development stage.A modern star tracker is a system, that can be represented as two modules, a digital camera module and a processing module. Use of a compact camera lens and a small-size image sensor allows to significantly reduce overall mass and size of the device, and at the same time, may cause significant image quality deterioration, due to increased distortion, uncompensated spherical and chromatic aberration, lower signal-to-noise ratio (SNR) and overall lower light sensitivity of the camera module. Thus, embedded software of the processing module, responsible for pre-processing, star identification and attitude calculation, should take into account the limitations imposed by the miniaturization of the camera module. At the same time, hardware architecture of the processing module should have the capacity to perform necessary correction of the digital image in real time, and to ensure stability and expected performance of the star identification and attitude calculation routines.The goal of hardware and software prototyping of a miniature star tracker system, carried out in this work, is to evaluate various design solutions, that could be brought into the camera or into the processing module, in order to help the miniaturization of the system. Another goal is to analyze the impact of every hardware and software component on the overall performance of a miniaturized star tracker system. Among the list of star tracker characteristics, the initial attitude estimation time and the attitude output rate became the focus of the research. Current work addresses possible performance bottlenecks, that may appear on any step of star tracker operation, from capturing starlight to calculation of components of the attitude quaternion, and proposes an original solution to speed-up the star identification routine.

The third-party tracking ecosystem continuously evolves in scope, therefore, understanding of it is at best elusive. In this thesis, we investigate this complex ecosystem from three dimen-sions. Firstly, we examine third-party trackers from a geographical perspective. We observe a non-uniform presence of local third-party trackers between regions and countries within re-gions, with some trackers focusing on specific regions and countries. Secondly, we focus on how trackers share user-specific identifiers (IDs). We identify user-specific IDs that we suspect are used to track users. We find a significant amount of ID-sharing practices across different organ-isations providing various service categories. Our observations reveal that ID-sharing happens at a large scale regardless of the user profile size and profile condition such as logged-in and logged-out. Finally, we quantify the effect of tracker-blockers, a popular option for the users to protect their privacy, on the page-load performance. The effect of such tools on the over-all user browsing experience is questionable as the blockage of trackers can disrupt the general website loading process. The tracker-blockers we studied have a considerable negative effect on page-load performance. Unexpectedly, we find that even highly popular websites are negatively affected. This thesis points to significant gaps in our knowledge about the inner workings of this complex ecosystem. Moreover, it highlights some of the challenges that we face when attempting to preserve user's privacy by using tracker-blockers.

Esta pesquisa traz um estudo sobre a construção inicial dos conceitos de limites e taxa de variação, com alunos do segundo ano do Ensino Médio da Escola Antônio de Castro Alves. Como metodologia utilizamos a perspectiva do Estudo de Caso (PONTE, 2006). O trabalho propõe a utilização do software Tracker Physics, que possibilita a análise de objetos em movimento gravados por vídeo a partir de diferentes registros gerados pelo software, tais como gráficos, tabelas e registros algébricos. Com o uso deste software e da teoria de Duval, procuramos responder à seguinte pergunta norteadora: como os alunos do Ensino Médio compreendem os conceitos de taxa de variação e de limite a partir de objetos em movimento analisados com o Tracker Physics? Por tratar-se de objetos em movimento, utilizamos a Física como meio para trabalharmos os conceitos matemáticos. Antes de chegarmos ao debate sobre limite e taxa de variação, a proposta levanta questões acerca da interpretação de gráficos, tabelas, equações e cálculos numéricos, que não são o escopo principal do trabalho, mas que são importantes para o processo de construção dos conceitos propostos, e a análise dos dados aponta resultados interessantes. Os dados da pesquisa são analisados à luz da teoria dos Registros Semióticos de Duval. Podemos apontar, ao final da pesquisa, que os alunos avançaram na compreensão dos conceitos abordados nas situações apresentadas e analisadas. / This research brings a study about the initial construction of the concepts of limits and rate of variation, with students of the second year of High School of the School Antônio de Castro Alves. As methodology we use the case study perspective (PONTE, 2006). The work proposes the use of Tracker Physics software, which enables the analysis of moving objects recorded by video from different records generated by the software, such as graphs, tables and algebraic records. With the use of this software and Duval's theory, we try to answer the following guiding question: how do the students of the High School understand the concepts of rate of variation and limit from moving objects analyzed with Tracker Physics? Because we are dealing with moving objects, we use Physics as the means to work on mathematical concepts. Before we reach the debate about limit and rate of variation, the proposal raises questions about the interpretation of graphs, tables, equations and numerical calculations, which are not the main scope of the work, but which are important for the process of construction of the proposed concepts , And the analysis of the data points interesting results. The data of the research is analyzed in light of the theory of the Duval Semiotic Registers. We can point out, at the end of the research, that the students advanced in understanding the concepts addressed in the situations presented and analyzed.

Submitted by Larissa Vitoria Cardoso Cusielo (larissavitoria@id.uff.br) on 2017-09-05T17:18:04Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Rafael Pinheiro Santos - Dissertação Final.pdf: 3826907 bytes, checksum: 9fc225c7d1e17bc76239ae3a282bfd50 (MD5) Rafael Pinheiro Santos - Produto Final.pdf: 2418114 bytes, checksum: e33fdbf6658370c3c052fc82d477414e (MD5) / Rejected by Biblioteca do Aterrado BAVR (bavr@ndc.uff.br), reason: Titulo em caixa alto on 2017-09-05T19:17:58Z (GMT) / Submitted by Larissa Vitoria Cardoso Cusielo (larissavitoria@id.uff.br) on 2017-09-05T19:44:52Z No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Rafael Pinheiro Santos - Dissertação Final.pdf: 3826907 bytes, checksum: 9fc225c7d1e17bc76239ae3a282bfd50 (MD5) Rafael Pinheiro Santos - Produto Final.pdf: 2418114 bytes, checksum: e33fdbf6658370c3c052fc82d477414e (MD5) / Approved for entry into archive by Biblioteca do Aterrado BAVR (bavr@ndc.uff.br) on 2017-09-27T21:48:05Z (GMT) No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Rafael Pinheiro Santos - Dissertação Final.pdf: 3826907 bytes, checksum: 9fc225c7d1e17bc76239ae3a282bfd50 (MD5) Rafael Pinheiro Santos - Produto Final.pdf: 2418114 bytes, checksum: e33fdbf6658370c3c052fc82d477414e (MD5) / Made available in DSpace on 2017-09-27T21:48:05Z (GMT). No. of bitstreams: 3 license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Rafael Pinheiro Santos - Dissertação Final.pdf: 3826907 bytes, checksum: 9fc225c7d1e17bc76239ae3a282bfd50 (MD5) Rafael Pinheiro Santos - Produto Final.pdf: 2418114 bytes, checksum: e33fdbf6658370c3c052fc82d477414e (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Universidade Federal Fluminense. Instituto de Ciências Exatas. Programa de Pós-Graduação em Ensino de Física. Volta Redonda, RJ / A proposta desta dissertação é apresentar o desenvolvimento de um produto educacional para ensinar Cinemática através de Vídeo análise utilizando o software Tracker para turmas do ensino médio. O produto educacional consiste em uma sequencia didática, que será conduzida por uma série de perguntas com o intuito de construir com os alunos, a partir da observação dos fenômenos e da experimentação, um modelo matemático dos movimentos tradicionalmente estudados no ensino médio. Para alicerçar o desenvolvimento deste produto, apresentamos uma breve fundamentação teórica sobre Cinemática, Aprendizagem Significativa e Tecnologia da Informação e Comunicação (TICs). Essa proposta de trabalho foi levada à sala de aula e os resultados da aplicação são avaliados pela técnica de análise de conteúdo aplicado à sequencia didática. Acreditamos que o produto apresentado pode participar diretamente da formação das Competências e Habilidades dos alunos. Além disso, a realização da vídeo análise motivou os estudantes e foi possível perceber um maior envolvimento nas atividades, o que é prerrogativa fundamental para atingir-se a aprendizagem significativa. / The purpose of this dissertation is to present the development of an educational product to teach kinematics through analysis video using the Tracker software for high school classes. The educational product consists on a didactic sequence, which will be conducted through a series of questions in order to build with students from the observation of phenomena and experimentation, a mathematical model of movements traditionally studied at high school. In support of the development of this product there is a brief theoretical framework of kinematics, Meaningful Learning and Information and Communication Technology (ICT). This work proposal was brought to the classroom and the application of the results are evaluated by content analysis technique applied to the teaching sequence. We believe that the product presented may participate directly in the formation of skills and abilities of the students. Furthermore, the realization of video analysis motivated the students and it was possible to observe a greater involvement in the activities, which is a fundamental prerogative to achieve meaningful learning.

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Many factors contribute to people's physical inactivity, but among the leading factors is a lack of motivation. Fitness trackers have been shown to encourage an increase in exercise, but they are frequently abandoned within a few short months. For this thesis I developed and asynchronous-play social gaming platform, FitPlay Games, to fill the gap in motivation left by current fitness trackers. By providing users with a variety of asynchronous cooperative and competitive gaming styles, this platform enable them to find a motivation technique that works best for their lifestyle and fitness prowess. The platform encourages prolonged use of fitness trackers, helping users to have more healthy lifestyles. Individual games are designed to allow both the novice and the maven to have a chance at winning, leveling the playing field, and increasing motivation to win. The effectiveness, usability, and enjoyability of the social games will be assessed, with an emphasis on understanding differences in play habits due to gender and lifestyle.

<p>A face tracker is exactly what it sounds like. It tracks a face in a video sequence. Depending on the complexity of the tracker, it could track the face as a rigid object or as a complete deformable face model with face expressions.</p><p>This report is based on the work of a real time feature based face tracker. Feature based means that you track certain features in the face, like points with special characteristics. It might be a mouth or eye corner, but theoretically it could be any point. For this tracker, the latter is of interest. Its task is to extract global parameters, i.e. rotation and translation, as well as dynamic facial parameters (expressions) for each frame. It tracks feature points using motion between frames and a textured face model (Candide). It then uses an extended Kalman filter to estimate the parameters from the tracked feature points.</p>

The Generic Nanosatellite Bus (GNB) is a spacecraft platform designed to accommodate the integration of diverse payloads in a common housing of supporting components. The development of the GNB at the Space Flight Laboratory (SFL) under the Canadian Advanced Nanospace eXperiment (CanX) program provides accelerated access to space while reducing non-recurring engineering (NRE) costs. The work presented herein details the development of the attitude determination and control subsystem (ADCS) of the GNB. Specific work on magnetorquer coil assembly, integration, and testing (AIT) and reaction wheel testing is included. The embedded software development and unit-level testing of the GNB sun sensors are discussed. The characterization of the AeroAstro star tracker is also a major focus, with procedures and results presented here. Hardware models were developed and incorporated into SFL's in-house high-fidelity attitude dynamics and control simulation environment. This work focuses on specific contributions to the CanX-3, CanX-4&5, and AISSat-1 nanosatellite missions.