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Localização e mapeamento simultâneos com auxílio visual omnidirecional. / Simultaneous localization and mapping with omnidirectional vision.Vitor Campanholo Guizilini 12 August 2008 (has links)
O problema da localização e mapeamento simultâneos, conhecido como problema do SLAM, é um dos maiores desafios que a robótica móvel autônoma enfrenta atualmente. Esse problema surge devido à dificuldade que um robô apresenta ao navegar por um ambiente desconhecido, construindo um mapa das regiões por onde já passou ao mesmo tempo em que se localiza dentro dele. O acúmulo de erros gerados pela imprecisão dos sensores utilizados para estimar os estados de localização e mapeamento impede que sejam obtidos resultados confiáveis após períodos de navegação suficientemente longos. Algoritmos de SLAM procuram eliminar esses erros resolvendo ambos os problemas simultaneamente, utilizando as informações de uma etapa para aumentar a precisão dos resultados alcançados na outra e viceversa. Uma das maneiras de se alcançar isso se baseia no estabelecimento de marcos no ambiente que o robô pode utilizar como pontos de referência para se localizar conforme navega. Esse trabalho apresenta uma solução para o problema do SLAM que faz uso de um sensor de visão omnidirecional para estabelecer esses marcos. O uso de sistemas de visão permite a extração de marcos naturais ao ambiente que podem ser correspondidos de maneira robusta sob diferentes pontos de vista. A visão omnidirecional amplia o campo de visão do robô e com isso aumenta a quantidade de marcos observados a cada instante. Ao ser detectado o marco é adicionado ao mapa que robô possui do ambiente e, ao ser reconhecido, o robô pode utilizar essa informação para refinar suas estimativas de localização e mapeamento, eliminando os erros acumulados e conseguindo mantê-las precisas mesmo após longos períodos de navegação. Essa solução foi testada em situações reais de navegação, e os resultados mostram uma melhora significativa nos resultados alcançados em relação àqueles obtidos com a utilização direta das informações coletadas. / The problem of simultaneous localization and mapping, known as the problem of SLAM, is one of the greatest obstacles that the field of autonomous robotics faces nowadays. This problem is related to a robots ability to navigate through an unknown environment, constructing a map of the regions it has already visited at the same time as localizing itself on this map. The imprecision inherent to the sensors used to collect information generates errors that accumulate over time, not allowing for a precise estimation of localization and mapping when used directly. SLAM algorithms try to eliminate these errors by taking advantage of their mutual dependence and solving both problems simultaneously, using the results of one step to refine the estimatives of the other. One possible way to achieve this is the establishment of landmarks in the environment that the robot can use as points of reference to localize itself while it navigates. This work presents a solution to the problem of SLAM using an omnidirectional vision system to detect these landmarks. The choice of visual sensors allows for the extraction of natural landmarks and robust matching under different points of view, as the robot moves through the environment. The omnidirectional vision amplifies the field of vision of the robot, increasing the number of landmarks observed at each instant. The detected landmarks are added to the map, and when they are later recognized they generate information that the robot can use to refine its estimatives of localization and mapping, eliminating accumulated errors and keeping them precise even after long periods of navigation. This solution has been tested in real navigational situations and the results show a substantial improvement in the results compared to those obtained through the direct use of the information collected.
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[en] APPLICATION METHOD OF MOMENTS FOR THE ANALYSIS OF CONICAL ANTENNAS / [pt] APLICAÇÃO DE MÉTODO DOS MOMENTOS NA ANÁLISE DE ANTENAS CÔNICASDENISE FREITAS SILVA 19 October 2005 (has links)
[pt] Neste estudo faz-se uma análise do desempenho de antenas
cônicas compactas para operar em largas bandas de
freqüência. Esta análise será feita observando o
comportamento da impedância da antena. Serão,
primeiramente, consideradas as estruturas convencionais
formadas por cones e cones sobrepostos próximos a um plano
condutor. Posteriormente, será considerada uma estrutura
cônica onde o arredondamento das bordas resulta em um
comportamento mais uniforme para a impedância de entrada
com variações da freqüência, conferindo um aumento na
banda para esta configuração. / [en] The discone antenna is well known as an easy to build
multioctave broadband antenna with a omnidirectional
radiation pattern in the H-plane, It comprises a plane
conductive disc element spaced close to and axially
aligned with a conductive cone element. For applications
in the UHF and microwave ranges, high performance antennas
have been designed to operate from 0.5 to 5 GHz with a
VSWR of about 3.5:1 or less. If the length is finite, the
impedance still strongly dependent on apex angle as long
as the cone is longer than about quarter of wavelength and
the apex angle is relatively larger. A problem that is
experienced with these antenna designs is the relatively
large size required to operate at the low frequencies. In
applications where utilization of this antenna. In this
work, the analysis and design of these antenna is obtained
by employing a rigorous formulation of the electromagnetic
scattering problem. As a design tool, we employ Method of
Moments for the analysis of rotationally symmetric
structures excited by TEM mode. To properly account the
variations in driven-point impedance with frequency, the
coaxial waveguide used to feed the antenna is also
included in the analysis. The excitation is simulated by a
distribution of equivalent electric and magnetic currents
placed inside the coaxial cable, over a cross-section
plane. These currents are defined such that only excite
the mode TEM towards the cable-antenna junction. These
numerical tool is employed in the shaping the metallic
surfaces involved in the discone-type antennas in order to
obtain more compact structures. Simple solutions can be
easily obtained making the center fed cone and the disc
element with radially outer edge portions rolled
backwardly and away from each other to form donut-shaped
configurations. The ruled edges not only reduce the
diameter of the antenna but also permit the current to
flow around them smoothly and without reflections that
degrade the VSWR at low end of the frequency band.
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[en] SYNTHESIS AND ANALYSIS OF CIRCULARLY SYMMETRIC REFLECTORS VIA PHYSICAL OPTICS AND FRINGE WAVE CURRENTS / [pt] ANÁLISE E SÍNTESE DE REFLETORES CIRCULARMENTE SIMÉTRICOS PELOS MÉTODOS DA ÓTICA FÍSICA E CORRENTES DE FRANJAMAIQUEL DOS SANTOS CANABARRO 08 January 2010 (has links)
[pt] O projeto de antenas refletoras para a geração de feixes modelados envolve
a construção de algoritmos baseados em métodos de análise eletromagnética
associados a técnica de otimização. Em geral, estes algoritmos demandam
considerável tempo de processamento computacional, impondo limites para sua
utilização intensiva na exploração de diferentes conjuntos de especificações e na
busca de soluções mais compactas. Neste trabalho, será considerada a síntese de
antenas refletoras circularmente simétricas para a geração de feixes modelados
circularmente simétricos. Em função das características de simetria da antena,
simplificações serão introduzidas na formulação do problema, reduzindo
substancialmente o tempo de processamento e viabilizando sua utilização
intensiva. Para a análise eletromagnética da antena refletora serão consideradas
as aproximações da Ótica Física (PO) e das correntes de franja (CF).
Considerando alimentadores radiando um campo com dependência azimutal
n=1, o algoritmo foi adaptado e aplicado no modelamento de antena refletora
para atender as especificações do CBERS (China-Brazil Earth Resources
Satellite). Para alimentadores com dependência azimutal n=0, foram
considerados sistemas de antenas omnidirecionais de um e dois refletores para a
geração de diagramas modelados no plano vertical. Para estes dois tipo de
sistema, o algoritmo de modelamento foi utilizado para maximizar o diagrama
em direção e para produzir diagramas com dependência do tipo cossecante ao
quadrado no plano vertical. A validação da técnica de análise eletromagnética
desenvolvida foi obtida comparando os resultados com os gerados via Métodos
dos Momentos. / [en] The usual algorithms employed in the design of shaped reflector antennas
for satellite applications embed an electromagnetic analysis method in an
optimization technique. In general, these algorithms demand considerable
computation time, limiting its intensive use in the study to explore different sets
of specifications and to search for more compact geometries. In this work, it is
considered the particular case of the shaping of circularly symmetric reflectors
antennas for the generation of circularly symmetric radiation patterns. The use
of the reflector surface properties simplifies the formulation of the
electromagnetic scattering and substantially reduces the computer time involved
in the optimization iteration. For the electromagnetic scattering, the algorithm
employed here considers the approximations given by the Physical Optics and
Fringe Currents methods. Firstly, the shaping algorithm was applied in the
design of a single reflector antenna to comply with the specifications of the
China-Brazil Earth Resources Satellite (CBERS). For this case, the feed
radiation pattern was represented by model with azimuthal dependence n=1. As
a second case, the shaping algorithm was applied in the design of single and dual
reflector omnidirectional antennas. Theses antennas were feed by a TEM coaxial
horn with azimuthal dependence n=1. For these two type of antenna
configurations, the modelling algorithm was used to maximize the diagram in
one direction or to produce radiation patterns with dependence of the type
cosecant to the square in the vertical plan. A Methods of Moments
electromagnetic analysis was used to validate the scattering fields yielded by the
PO+Fringe currents approximations.
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Multimodal 3D User Interfaces for Augmented Reality and Omni-Directional VideoRovelo Ruiz, Gustavo Alberto 29 July 2015 (has links)
[EN] Human-Computer Interaction is a multidisciplinary research field that combines, amongst others, Computer Science and Psychology. It studies human-computer interfaces from the point of view of both, technology and the user experience.
Researchers in this area have now a great opportunity, mostly because the technology required to develop 3D user interfaces for computer applications (e.g. visualization, tracking or portable devices) is now more affordable than a few years ago.
Augmented Reality and Omni-Directional Video are two promising examples of this type of interfaces where the user is able to interact with the application in the three-dimensional space beyond the 2D screen.
The work described in this thesis is focused on the evaluation of interaction aspects in both types of applications. The main goal is contributing to increase the knowledge about this new type of interfaces to improve their design. We evaluate how computer interfaces can convey information to the user in Augmented Reality applications exploiting human multisensory capabilities. Furthermore, we evaluate how the user can give commands to the system using more than one type of input modality, studying Omnidirectional Video gesture-based interaction.
We describe the experiments we performed, outline the results for each particular scenario and discuss the general implications of our findings. / [ES] El campo de la Interacción Persona-Computadora es un área multidisciplinaria que combina, entre otras a las Ciencias de la Computación y Psicología. Estudia la interacción entre los sistemas computacionales y las personas considerando tanto el desarrollo tecnológico, como la experiencia del usuario.
Los dispositivos necesarios para crear interfaces de usuario 3D son ahora más asequibles que nunca (v.gr. dispositivos de visualización, de seguimiento o móviles) abriendo así un área de oportunidad para los investigadores de esta disciplina. La Realidad Aumentada y el Video Omnidireccional son dos ejemplos de este tipo de interfaces en donde el usuario es capaz de interactuar en el espacio tridimensional más allá de la pantalla de la computadora.
El trabajo presentado en esta tesis se centra en la evaluación de la interacción del usuario con estos dos tipos de aplicaciones. El objetivo principal es contribuir a incrementar la base de conocimiento sobre este tipo de interfaces y así, mejorar su diseño.
En este trabajo investigamos de qué manera se pueden emplear de forma eficiente las interfaces multimodales para proporcionar información relevante en aplicaciones de Realidad Aumentada. Además, evaluamos de qué forma el usuario puede usar interfaces 3D usando más de un tipo de interacción; para ello evaluamos la interacción basada en gestos para Video Omnidireccional.
A lo largo de este documento se describen los experimentos realizados y los resultados obtenidos para cada caso en particular. Se presenta además una discusión general de los resultados. / [CAT] El camp de la Interacció Persona-Ordinador és una àrea d'investigació multidisciplinar que combina, entre d'altres, les Ciències de la Informàtica i de la Psicologia. Estudia la interacció entre els sistemes computacionals i les persones considerant tant el desenvolupament tecnològic, com l'experiència de l'usuari.
Els dispositius necessaris per a crear interfícies d'usuari 3D són ara més assequibles que mai (v.gr. dispositius de visualització, de seguiment o mòbils) obrint així una àrea d'oportunitat per als investigadors d'aquesta disciplina. La Realitat Augmentada i el Vídeo Omnidireccional són dos exemples d'aquest tipus d'interfícies on l'usuari és capaç d'interactuar en l'espai tridimensional més enllà de la pantalla de l'ordinador.
El treball presentat en aquesta tesi se centra en l'avaluació de la interacció de l'usuari amb aquests dos tipus d'aplicacions. L'objectiu principal és contribuir a augmentar el coneixement sobre aquest nou tipus d'interfícies i així, millorar el seu disseny. En aquest treball investiguem de quina manera es poden utilitzar de forma eficient les interfícies multimodals per a proporcionar informació rellevant en aplicacions de Realitat Augmentada. A més, avaluem com l'usuari pot utilitzar interfícies 3D utilitzant més d'un tipus d'interacció; per aquesta raó, avaluem la interacció basada en gest per a Vídeo Omnidireccional.
Al llarg d'aquest document es descriuen els experiments realitzats i els resultats obtinguts per a cada cas particular. A més a més, es presenta una discussió general dels resultats. / Rovelo Ruiz, GA. (2015). Multimodal 3D User Interfaces for Augmented Reality and Omni-Directional Video [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/53916 / TESIS
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Všesměrový synchronní podvozek / Omnidirectional chassisMejzlík, Bohumír January 2009 (has links)
The master's thesis deals with the functional model design of the omnidirectional chassis and its implementation. It is focused on construction of the omnidirectional chassis and choosing the suitable hardware equipment.It also deals with a project of control software for a mini-computer and a design of graphic application in the PC.
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Design and Testing of a Reciprocating Wind HarvesterTopcuoglu, Ahmet 24 June 2019 (has links)
Renewable energy sources are vital to reduce dependence on fossil fuels that are harmful for the environment and release greenhouse gases causing global warming. Wind energy is a natural source of energy that is abundant in the environment. While wind turbines are most popular, convenient, and used to harvest energy at large scales, there have been recent studies focusing on harvesting energy from the wind for microdevices. Such micro wind energy harvesters can decrease dependence on batteries.
In this study, a novel, framed flag micro wind harvester was designed and tested, and its behavior at three different wind speeds was experimentally examined in a wind tunnel. The main purpose of this study is to determine the geometric and wind speed conditions under which regular flapping occurs in the flag material.
A high-speed camera was used to visualize the motion of the harvester at different wind speeds and at various parametric ratios of the flag material length to the frame length. The movies taken by the camera are analyzed using Image J software to find the flapping frequency, flapping angle, and the amplitude. Nondimensional parameters such as the Re number and St number also are calculated.
This study finds that parametric ratios of 1.1 and 1.2 with the medium wind speed condition of 5 m/s are optimal flapping conditions. These optimal conditions would conveniently allow the use of piezoelectric material as the flag material in order to harvest energy. Further, an advantage of this novel design over previous designs is that the wind harvester naturally aligns with the wind direction and is thus omnidirectional.
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Compact Omnidirectional Millimeter-Wave Antenna Array Using Substrate Integrated Waveguide Technique and Efficient Modeling ApproachLiu, Yuanzhi 22 April 2021 (has links)
In this work, an innovative approach for effective modeling of substrate integrated waveguide (SIW) devices is firstly proposed. Next, a novel substrate integrated waveguide power splitter is proposed to feed antenna array elements in series. This feed network inherently provides uniform output power to eight quadrupole antennas. More importantly, it led to a compact configuration since the feed network can be integrated inside the elements without increasing the overall array size. Its design procedure is also presented.
Then, a series feed network was used to feed a novel compact omnidirectional antenna array. Targeting the 5G 26 GHz mm-wave frequency band, simulated results showed that the proposed array exhibits a broad impedance bandwidth of 4.15 GHz and a high gain of 13.6 dBi, which agree well with measured results. Its attractive features indicate that the proposed antenna array is well suitable for millimeter-wave wireless communication systems.
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Omnidirectional Optical Flow and Visual Motion Detection for Autonomous Robot NavigationStratmann, Irem 06 December 2007 (has links)
Autonomous robot navigation in dynamic environments requires robust detection of egomotion and independent motion. This thesis introduces a novel solution to the problem of visual independent motion detection by interpreting the topological features of omnidirectional dense optical flow field and determining the background - egomotion direction. The thesis solves the problem of visual independent motion detection in four interdependent subtasks. Independent Motion Detection can only be accomplished if the egomotion detection yields a relevant background motion model. Therefore, the problem of Egomotion Detection is solved first by exploiting the topological structures of the global omnidirectional optical flow fields. The estimation of the optical flow field is the prerequisite of the Egomotion-Detection task. Since the omnidirectional projection introduces non-affine deformations on the image plane, the known optical flow calculation methods have to be modified to yield accurate results. This modification is introduced here as another subtask, Omnidirectional Optical Flow Estimation. The experiments concerning the 3D omnidirectional scene capturing are grouped under the fourth subtask 3D Omni-Image Processing.
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Détection et suivi de personnes par vision omnidirectionnelle : approche 2D et 3D / Detection and tracking of persons by omnidirectional vision : 2D and 3D approachesBoui, Marouane 14 May 2018 (has links)
Dans cette thèse, nous traiterons du problème de la détection et du suivi 3D de personnes dans des séquences d'images omnidirectionnelles, dans le but de réaliser des applications permettant l'estimation de pose 3D. Ceci nécessite, la mise en place d'un suivi stable et précis de la personne dans un environnement réel. Dans le cadre de cette étude, on utilisera une caméra catadioptrique composée d'un miroir sphérique et d'une caméra perspective. Ce type de capteur est couramment utilisé dans la vision par ordinateur et la robotique. Son principal avantage est son large champ de vision qui lui permet d'acquérir une vue à 360 degrés de la scène avec un seul capteur et en une seule image. Cependant, ce capteur va engendrer des distorsions importantes dans les images, ne permettant pas une application directe des méthodes classiquement utilisées en vision perspective. Cette thèse traite de deux approches de suivi développées durant cette thèse, qui permettent de tenir compte de ces distorsions. Elles illustrent le cheminement suivi par nos travaux, nous permettant de passer de la détection de personne à l'estimation 3D de sa pose. La première étape de nos travaux a consisté à mettre en place un algorithme de détection de personnes dans les images omnidirectionnelles. Nous avons proposé d'étendre l'approche conventionnelle pour la détection humaine en image perspective, basée sur l'Histogramme Orientés du Gradient (HOG), pour l'adapter à des images sphériques. Notre approche utilise les variétés riemanniennes afin d'adapter le calcul du gradient dans le cas des images omnidirectionnelles. Elle utilise aussi le gradient sphérique pour le cas les images sphériques afin de générer notre descripteur d'image omnidirectionnelle. Par la suite, nous nous sommes concentrés sur la mise en place d'un système de suivi 3D de personnes avec des caméras omnidirectionnelles. Nous avons fait le choix de faire du suivi 3D basé sur un modèle de la personne avec 30 degrés de liberté car nous nous sommes imposés comme contrainte l'utilisation d'une seule caméra catadioptrique. / In this thesis we will handle the problem of 3D people detection and tracking in omnidirectional images sequences, in order to realize applications allowing3D pose estimation, we investigate the problem of 3D people detection and tracking in omnidirectional images sequences. This requires a stable and accurate monitoring of the person in a real environment. In order to achieve this, we will use a catadioptric camera composed of a spherical mirror and a perspective camera. This type of sensor is commonly used in computer vision and robotics. Its main advantage is its wide field of vision, which allows it to acquire a 360-degree view of the scene with a single sensor and in a single image. However, this kind of sensor generally generates significant distortions in the images, not allowing a direct application of the methods conventionally used in perspective vision. Our thesis contains a description of two monitoring approaches that take into account these distortions. These methods show the progress of our work during these three years, allowing us to move from person detection to the 3Destimation of its pose. The first step of this work consisted in setting up a person detection algorithm in the omnidirectional images. We proposed to extend the conventional approach for human detection in perspective image, based on the Gradient-Oriented Histogram (HOG), in order to adjust it to spherical images. Our approach uses the Riemannian varieties to adapt the gradient calculation for omnidirectional images as well as the spherical gradient for spherical images to generate our omnidirectional image descriptor.
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Vector Wavelet Transforms for the Coding of Static and Time-Varying Vector FieldsHua, Li 02 August 2003 (has links)
Compression of vector-valued datasets is increasingly needed for addressing the significant storage and transmission burdens associated with research activities in large-scale computational fluid dynamics and environmental science. However, vector-valued compression schemes have traditionally received few investigations within the data-compression community. Consequently, this dissertation conducts a systematic study of effective algorithms for the coding of vectorvalued datasets and builds practical embedded compression systems for both static and timevarying vector fields. In generalizing techniques from the relatively mature field of image and video coding to vector data, three critical issues must be addressed: the design of a vector wavelet transform (VWT) that is amenable to vector-valued compression applications, the implementation of vector-valued intraframe coding that enables embedded coding, and the investigation of interframe-compression techniques that are appropriate for the complex temporal evolutions of vector features. In this dissertation, we initially invoke multiwavelets to construct VWTs. However, a balancing problem arises when existing multiwavelets are applied directly to vector data. We analyze extensively this performance failure and develop the omnidirectional balancing (OB) design criterion to rectify it. Employing the OB principle, we derive with a family of biorthogonal multiwavelets possessing desired balancing and symmetry properties and yielding performance far superior to that of VWTs implemented via other multiwavelets. In the second part of the dissertation, quantization schemes for vector-valued data are studied, and a complete embedded coding system for static vector fields is designed by combining a VWT with suitable vector-valued successive-approximation quantization. Finally, we extend several interframecompression techniques from video-coding applications to vector sequences for the compression of time-varying vector fields. Since the complexity of temporal evolutions of vector features limits the efficiency of the simple motion models which have been successful for natural video sources, we develop a novel approach to motion compensation which involves applying temporal decorrelation to only low-resolution information. This reduced-resolution motion-compensation technique results in significant improvement in terms of rate-distortion performance.
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