• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 5
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 16
  • 16
  • 9
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Spécifications et analyse d'un pilote automatique embarqué de métro type V.A.L

Azouni, Mahrez 17 December 1979 (has links) (PDF)
Etude des spécifications fonctionnelles puis opérationnelles du cahier des charges. Représentation du cahier des charges à l'aide du GRAFCET. Conception du modèle fonctionnel du pilote automatique. Analyse quantitative du modèle. Analyse de la sécurité.
12

Implementation and Applications of an Anti-Collision Differential-Offset Spread Spectrum RFID System

Rohatgi, Anil 11 August 2006 (has links)
This report documents the design, construction, and implementation of a differential-offset spread spectrum RFID system, to avoid the problem of anti-collision interference from multiple RFID tags. Currently in industry, this problem is handled by establishing a two way communication link between the tags and the interrogator. The proposed system eliminates the need for the excessive hardware use to create this link, and therefore drastically reduces the cost of each tag. Not only is this system cheaper to implement but it is faster, requires less power, and by the nature of the design contains an inherent encryption scheme for the data being transmitted. Specialized RFID tags were designed and fabricated in order to produce a pseudo random code unique to each tag. The design presented in this document allowed simultaneous interrogation of up to 255 tags within one sensing environment. Once queried, the tags then modulate the incoming signal from the interrogator with their own sequence, and reflect the signal back to the interrogator. What the interrogator then receives is a combination of backscatter from all of the tags within the sensing environment. Specialized software written in Matlab and LabView uses these unique sequences to isolate the data from a desired tag away from the sea of information being transmitted from every tag. Using this system, numerous applications for experiments and measurements can be devised. One such application this thesis focuses on is the use of this system to simultaneously measure signal strengths from multiple diversity antennas in order to optimize their position and orientation. Currently, the majority of antenna diversity measurements are taken by measuring the signal strength of a given configuration one antenna at a time. By using the anti-collision RFID system proposed above, the signal strength produced by both antennas can be measured and recorded simultaneously to provide a true representation of their combined performance. This measurement can be used to find the optimal configuration for multiple antennas. This thesis will fully explore the theories and procedures behind creating this system, and will provide the results and analysis of its performance.
13

Um Sistema Anticolisão 3D baseado no método de Campo Potencial Artificial para um robô móvel

Morais, Carlos Eduardo Silva 16 February 2017 (has links)
Submitted by Fernando Souza (fernandoafsou@gmail.com) on 2017-08-11T14:01:11Z No. of bitstreams: 1 arquivototal.pdf: 11420527 bytes, checksum: 9c4b07869f327f3f311a4d4c15f0210b (MD5) / Made available in DSpace on 2017-08-11T14:01:11Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 11420527 bytes, checksum: 9c4b07869f327f3f311a4d4c15f0210b (MD5) Previous issue date: 2017-02-16 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Anti-collision systems are based on sensing and estimating the mobile robot pose (coordinates and orientation), with respect to its environment. Obstacles detection, path planning and pose estimation are primordial to ensure the autonomy and safety of the robot, in order to reduce the risk of collision with objects and living beings that share the same space. For this, the use of RGB-D sensors, such as the Microsoft Kinect, has become popular in the last years, for being relative accurate and low cost sensors. In this work we propose a new 3D anti-collision algorithm based on Artificial Potential Field method, that is able to make a mobile robot pass between closely spaced obstacles, minimizing the oscillations during the cross. We develop our Unmanned Ground Vehicles (UGV) system on a ’Turtlebot 2’ platform, with which we perform the experiments. / Sistemas anti-colisão são baseados na percepção e estimação da pose do robô móvel (coordenadas e orientação), em referência ao ambiente em que ele se encontra. A detecção de obstáculos, planejamento de caminhos e estimação da pose são fundamentais para assegurar a autonomia e a segurança do robô, no intuito de reduzir o risco de colisão com objetos ou pessoas que dividem o mesmo espaço. Para isso, o uso de sensores RGB-Ds, tal como o Microsoft Kinect, vem se tornando popular nos últimos anos, por serem sensores relativamente precisos e de baixo custo. Nesse trabalho nós propomos um novo algoritmo anti-colisão 3D baseado no método de Campo Potencial Artificial, que é capaz de fazer um robô móvel passar em espaços estreitos, entre obstáculos, minimizando as oscilações, que é uma característica comum desse tipo de método, durante seu deslocamento. Foi desenvolvido um sistema para plataforma robótica ’Turtlebot 2’, o qual foi utilizado para realizar todos os experimentos.
14

Drönarljusuppvisning : Ett system för en samlad drönarsvärm för ljusuppvisningar i luften / Drone Light Display : An edge deployed collaborative drone swarming system for aerial light display

Wretblad, Niklas, Aarnio, Linus, Dahlgren, Eric, Elfstrand, Simon, Nolkrantz, Marcus, Sehlstedt, Robert, Landgren, Kasper January 2020 (has links)
Den här rapporten beskriver och behandlar resultatet av ett kandidatarbete som utfördes i kursen TDDD96:Kandidatprojekt i programvaruutveckling som ges vid Linköpings universitet. Namnet på projektet som har utförts är Drone Light Display och det beställdes av RISE Research Institutes of Sweden AB. Den division av RISE som har lokaler på Linköpings universitet är inriktade på drönarforskning. Uppdraget blev därför att skapa en algoritm för att detektera och undvika kollision mellan drönare samt implementera ett omkringliggande system för att generera ljusshower med hjälp av drönare som flyger i formation. Projektet utfördes av sju tredjeårsstudenter som studerar till Civilingenjör i data- respektive mjukvaruteknik vid Linköpings universitet. Det resulterade i två användargränssnitt, ett för hantering av ljusshower och ett för statuskontroll av drönare, två servrar och en antikollisionsmodul. Antikollisionsmodulen körs som en separat process på varje drönare och är kompatibel med RISE:s egna styrsystem, Drone Safety Service. De båda servrarna tar emot en rad information från drönarna och sammanställer och skickar sedan ut denna till alla drönare och antikollisionsmodulen. På så sätt får antikollisionsmodulen tillgång till den information som behövs för att kunna ta informerade beslut så att drönarna kan undvika kollisioner. Avslutningsvis innehåller rapporten individuella bidrag från varje projektmedlem inom diverse ämnen som är kopplade till mjukvaruutveckling eller till projektet i allmänhet.
15

Mecanismo de controle de potência para estimativa de etiquetas em redes de identificação por rádio frequência

Lucena Filho, Walfredo da Costa 03 August 2015 (has links)
Submitted by Geyciane Santos (geyciane_thamires@hotmail.com) on 2015-11-23T21:24:44Z No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-11-30T19:51:08Z (GMT) No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-11-30T19:55:39Z (GMT) No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) / Made available in DSpace on 2015-11-30T19:55:40Z (GMT). No. of bitstreams: 1 Dissertação - Walfredo da Costa Lucena Filho.pdf: 2083187 bytes, checksum: 72f63311dba60bbea7ef2d5cc474c601 (MD5) Previous issue date: 2015-08-03 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / An RFID system is typically composed of a reader and a set of tags. An anti-collision algorithm is necessary to avoid collision between tags that respond simultaneously to a reader. The most widely used anti-collision algorithm is DFSA (Dynamic Framed Slotted ALOHA) due to its simplicity and low computational cost. In DFSA algorithms, the optimal TDMA (Time Division Multiple Access) frame size must be equal to the number of unread tags. If the exact number of tags is unknown, the DFSA algorithm needs a tag estimator to get closer to the optimal performance. Currently, applications have required the identification of large numbers of tags, which causes an increase in collisions and hence the degradation in performance of the traditional algorithms DFSA. This work proposes a power control mechanism to estimate the number of tags for radio frequency identification networks (RFID). The mechanism divides the interrogation zone into subgroups of tags and then RSSI (Received Signal Strength Indicator) measurements estimate the number of tags in a subarea. The mechanism is simulated and evaluated using a simulator developed in C/C++ language. In this study, we compare the number of slots and identification time, with ideal DFSA algorithm and Q algorithm EPCglobal standard. Simulation results shows the proposed mechanism provides 99% performance of ideal DFSA in dense networks, where there are many tags. Regarding the Q algorithm, we can see the improvement in performance of 6.5%. It is also important to highlight the lower energy consumption of the reader comparing to ideal DFSA is 63%. / Um sistema de identificação por rádio frequência (RFID) é composto basicamente de um leitor e etiquetas. Para que o processo de identificação das etiquetas seja bem sucedido, é necessário um algoritmo anticolisão a fim de evitar colisões entre etiquetas que respondem simultaneamente à interrogação do leitor. O algoritmo anticolisão mais usado é o DFSA (Dynamic Framed Slotted ALOHA) devido à sua simplicidade e baixo custo computacional. Em algoritmos probabilísticos, tal como o DFSA, o tamanho ótimo do quadro TDMA (Time Division Multiple Access) utilizado para leitura das etiquetas deve ser igual à quantidade de etiquetas não lidas. Uma vez que no processo de leitura, normalmente não se sabe a quantidade exata de etiquetas, o algoritmo DFSA faz uso de um estimador para obter um desempenho mais próximo do ideal. Atualmente, as aplicações têm demandado a identificação de grandes quantidades de etiquetas, o que ocasiona um aumento das colisões e, consequentemente, a degradação no desempenho dos algoritmos DFSA tradicionais. Este trabalho propõe um mecanismo de controle de potência para estimar a quantidade de etiquetas em redes de identificação por rádio frequência (RFID). O mecanismo baseia-se na divisão da área de interrogação em subáreas e, consequentemente, subgrupos de etiquetas. Tal divisão é utilizada para realizar medições de RSSI (Received Signal Strength Indicator) e, assim, estimar a quantidade de etiquetas por subárea. O mecanismo é simulado e avaliado utilizando um simulador próprio desenvolvido em linguagem C/C++. Neste estudo, comparam-se os resultados de quantidade de slots e tempo de identificação das etiquetas, com os obtidos a partir da utilização dos algoritmos DFSA ideal e algoritmo padrão Q da norma EPCglobal. A partir dos resultados da simulação, é possível perceber que o mecanismo proposto apresenta desempenho 99% do DFSA ideal em redes densas, onde há grande quantidade de etiquetas. Em relação ao algoritmo Q, percebe-se a melhoria de 6,5% no desempenho. É importante ressaltar também a redução no consumo de energia do leitor em torno de 63% em relação ao DFSA ideal.
16

Contribution à la réalisation d’un oscillateur push-push 80GHz synchronisé par un signal subharmonique pour des applications radars anticollisions

Ameziane El Hassani, Chama 06 May 2010 (has links)
Ce travail de thèse s’inscrit dans le cadre d’un projet Français « VéLo » qui est une collaboration entre l’industriel STMicroelectronics et plusieurs laboratoires dont les laboratoires IMS-bordeaux et LAAS. Le but du projet est de concevoir un prototype de radar anticollision millimétrique. Dans ce travail un synthétiseur de fréquence est implémenté. Ce dernier sera intégré dans la chaine de réception du démonstrateur. Une étude bibliographique des architectures classiques de système de radiocommunication a été réalisée. Des exemples d’architectures rencontrées dans le domaine millimétrique ont été étudiés.L’objet principal de cette thèse est l’étude des oscillateurs synchronisés par injection ILO. L’objectif est de réaliser un oscillateur verrouillé par injection qui sera piloté par un oscillateur de fréquence plus basse possédant des caractéristiques de stabilité et de bruit meilleures.Dans ce travail de thèse, le mécanisme de verrouillage des oscillateurs par injection a été décrit. Un modèle de synchronisation par injection série, basé sur la théorie de Huntoon Weiss et inspiré du travail de Badets réalisé sur les oscillateurs synchrones verrouillés par injection parallèle, est proposé. La théorie établie a permis d’exprimer la plage de synchronisation en fonction de la topologie utilisée et des composants de la structure. La validité de la théorie a été évaluée par la simulation de la structure. Les résultats présentés montrent une bonne concordance entre la simulation et la théorie et permettent de valider le principe de synchronisation par injection. La faisabilité de l’intégration d’un ILO millimétrique synchronisé par l’harmonique d’un signal de référence de fréquence plus basse a été démontrée expérimentalement. Le synthétiseur de fréquence est réalisé en technologie BiCMOS 130nm pour des applications millimétriques de STMicroelectronics. Ce dernier opère dans une plage de 2GHz autour de la fréquence 82,5GHz. Les performances en bruit du synthétiseur sont satisfaisantes. Le bruit de phase de l’ILO recopie celui du signal injecté. Les équipements de mesures utilisés, le bruit de phase de l’oscillateur atteint des valeurs inférieures à -110dBc/Hz à 1MHz de la porteuse. / This thesis is a part of a French project "VELO". The project is collaboration between STMicroelectronics and several laboratories including IMS-Bordeaux and LAAS laboratories. The aim of this project is to achieve a prototype of millimeter anti-collision radar. In this work a frequency synthesizer is implemented. This circuit will be incorporated in the reception chain of the demonstrator. A bibliographical study of classical architecture was completed. Examples of architectures encountered in the millimeter frequency range have been studied. The purpose of this thesis is to study the phenomena of synchronization in oscillators. The objective is to design an injection locked oscillator ILO driven by another oscillator, the second oscillator operates at lower frequency and offers better stability and noise characteristics.In this thesis, the injection locking mechanism of the oscillators has been described. A model of synchronization by series injection is proposed. The model is based on the theory of Huntoon and Weiss and inspired by Badets’ work performed on parallel injection. The theory expresses the synchronized frequency range depending on the used topology and the values of the components. The validity of the theory was evaluated by simulation. The results show good agreement between simulation and theory and validate the principle of synchronization by injection.The feasibility of a millimeter ILO synchronized by the harmonic of a reference signal operating at lower frequency has been demonstrated experimentally. The synthesizer was implemented in BiCMOS technology for 130nm applications millimeter of STMicroelectronics. The oscillator operates at 82.5 GHz and performs a frequency range of 2GHz. The noise performance of the synthesizer is satisfactory. The phase noise of the ILO depends on the reference phase noise, and reaches values of -110dBc/Hz at 1MHz from the carrier frequency.

Page generated in 0.0659 seconds