• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 135
  • 64
  • 58
  • 45
  • 18
  • 12
  • 9
  • 9
  • 8
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • Tagged with
  • 405
  • 128
  • 110
  • 60
  • 47
  • 39
  • 38
  • 30
  • 28
  • 27
  • 26
  • 26
  • 25
  • 25
  • 24
  • 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.
101

Exterior inspection of an aircraft using a Pan-Tilt-Zoom camera and a 3D scanner moved by a mobile robot : 2D image processing and 3D point cloud analysis / Inspection de l'extérieur d'un aéronef à partir d'une caméra Pan-Tilt-Zoom et d'un scanner 3D portés par un robot mobile : analyse d'images et de nuages de points 3D

Jovančević, Igor 21 November 2016 (has links)
Cette thèse s’inscrit dans le cadre d’un projet industriel multi-partenaires ayant pour objectif le développement d’un robot mobile collaboratif (un cobot), autonome dans ses mouvements au sol, capable de réaliser l’inspection visuelle d’un aéronef, à la fois en phase de petite ou grande maintenance dans un hangar ou en phase de pré-vol sur le tarmac d’un aéroport. Le cobot est équipé de capteurs lui permettant d’effectuer ses tâches de navigation autonome, mais également d’un ensemble de capteurs optiques constituant la tête d’inspection : une caméra orientable Pan-Tilt-Zoom et un scanner 3D qui délivrent respectivement des données sous forme d’images 2D et de nuages de points 3D. L’objectif de la thèse est de développer des algorithmes d’analyse d’images 2D et de nuages de points 3D, afin d’établir un diagnostic sur l’état de l’avion et son aptitude à voler. Nous avons développé des algorithmes pour vérifier certains éléments de l’appareil, tels que valves, portes, capteurs, pneus ou moteurs, et également pour détecter et caractériser des dommages 3D sur le fuselage (impacts, rayures, etc.). Nous avons exploité dans nos algorithmes les connaissances a priori disponibles, en particulier le modèle 3D CAO de l’avion (un AIRBUS A320 dans le cadre de nos essais). Durant ces travaux de la thèse, nous avons pu répondre à deux besoins (parfois antagonistes) : développer des algorithmes d’inspection rapides et robustes, mais également répondre aux exigences spécifiques d’un projet industriel qui visait à développer un prototype opérationnel. Nous nous sommes attachés à développer des algorithmes les plus génériques possibles, de manière à ce qu’ils puissent être utilisés pour d’autres types d’inspection, tels que l’inspection de bâtiments ou de navires par exemple. Nous avons aussi contribué au développement du prototype (robot mobile équipé de capteurs) en développant le module de contrôle des capteurs d’inspection et en intégrant nos codes sur le robot avec les autres modules développés par les partenaires. Le prototype a fait l’objet de nombreux essais en hangar de maintenance ou sur tarmac. / This thesis makes part of an industry oriented multi-partners project aimed at developing a mobile collaborative robot (a cobot), autonomous in its movements on the ground, capable of performing visual inspection of an aircraft during short or long maintenance procedures in the hangar or in the pre-flight phase on the tarmac. The cobot is equipped with sensors for realizing its navigation tasks as well as with a set of optical sensors which constitute the inspection head: an orientable Pan-Tilt-Zoom visible light camera and a three-dimensional scanner, delivering data in the format of two-dimensional images and three-dimensional point clouds, respectively. The goal of the thesis is to propose original approaches for processing 2D images and 3D clouds, with intention to make a decision with respect to the flight readiness of the airplane. We developed algorithms for verification of the aircraft items such as vents, doors, sensors, tires or engine as well as for detection and characterization of three-dimensional damages on the fuselage. We integrated a-priori knowledge on the airplane structure, notably numerical three-dimensional CAD model of the Airbus-A320. We argue that with investing effort to develop robust enough algorithms and with the help of existing optical sensors to acquire suitable data, we can come up with non-invasive, accurate, and time-efficient system for automatic airplane exterior inspection. The thesis work was placed in between two main requirements: develop inspection algorithms which could be as general as possible and also meet the specific requirements of an industry oriented project. Often, these two goals do not go along and the balance had to be made. On one side, we were aiming to design and assess the approaches that can be employed on other large structures, for ex. buildings, ships. On the other hand, writing source code for controlling sensors as well as integrating our whole developed source code with other modules on the real-time robotic system, were necessary in order to demonstrate the feasibility of our robotic prototype.
102

Design, simulation and fabrication of a vertical microscanner for phase modulation interferometry - Application to optical coherence tomography system for skin imaging / Design, simulation et fabrication d'un micro-scanner vertical pour l'inférométrie à modulation de phase

Lullin, Justine 17 December 2015 (has links)
Cette thèse décrit le design, la simulation et la fabrication d’une matrice 4x4 de micro-miroirs actionnée verticalement et munie d’un capteur de position. Le micro-scanneur vertical a pour vocation à être intégré au sein d’un micro-interféromètre de Mirau de type matriciel, réalisé àbase de composants micro-optiques fabriqués grâce à des méthodes collectives. Le mouvement du micro-scanneur, développé dans cette thèse, génère un signal de référence utilisé pour l’implémentation de l’interférométrie à modulation de phase dans un système de tomographie par cohérence optique (OCT). Dans un premier temps, la thèse introduit le besoin d’un système d’imagerie adapté pour la détection précoce des cancers de la peau et établit les spécifications optiques requises par cette application. A partir de ces spécifications, le design du système OCT basé sur le micro-interféromètre de Mirau est présenté. En parallèle, l’état de l’art des technologies de micro-actionnement est décrit et un actionnement électrostatique à base de peignes interdigités est choisi pour actionner et lire la position de la matrice de micro-miroirs. En effet ce type d’actionnement bénéficie d’une bonne compatibilité avec le design du micro-interféromètre de Mirau. Dans un second temps, le cœur de la thèse expose le développement du micro-scanneur vertical, c.à.d le design et les simulations ainsi que la fabrication et la caractérisation. / This thesis describes the design, simulation and fabrication of a vertically actuated 4x4 array ofmicromirrors with embedded position sensing function. The vertical microscanner is meant to beintegrated within an array-type Mirau microinterferometer realized with optical microcomponentsfabricated using collective techniques. The microscanner, developed in this thesis, provides areference signal that is used for the implementation of phase modulation interferometery in an opticalcoherence tomography (OCT) system. This thesis first introduces the need for adapted imagingsystems for the early diagnosis of skin cancer and establishes the optical specifications requiredby this specific application. Based on these specifications, the design of the OCT system based onthe Mirau microinterferometer is presented. In parallel, the state of the art of the microactuationtechnologies is discussed and comb drive electrostatic actuation is chosen, for its compatibilitywith the design of the Mirau microinterferometer, to actuate and sense the position of the array ofmicromirrors. Then, the core of the thesis deals with the development of the vertical microscanner,i.e. its design and simulations, its fabrication and its characterization.
103

Controle automatizado para scanners de luz / Automated control of light beam scanners

Menezes Junior, Luiz Ferreira 16 July 2004 (has links)
Orientador: Paulo Roberto Gardel Kurka / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T02:13:27Z (GMT). No. of bitstreams: 1 MenezesJunior_LuizFerreira_M.pdf: 3960270 bytes, checksum: 542b501adbaca7fc3d8ff80120fab0d3 (MD5) Previous issue date: 2004 / Resumo: Este trabalho apresenta um método de controle automatizado de scanners de luz baseado no posicionamento dos projetores. É desenvolvida ainda uma estratégia de posicionamento dos focos de luz, através de acionamento sincronizado por sinais de áudio. Todos os modos de controle desenvolvidos são incorporados a um software de gerenciamento. No processo de controle toma-se necessário também a construção de uma interface de dados baseada no protocolo PC-DMX512. O trabalho contempla ainda uma descrição detalhada de tal protocolo e do hardware construído. O resultado final é ilustrado através de exemplos e do manual de operação do software de controle / Abstract: The work presents a method for automatically positioning of the light beam scanners. A strategy for synchronizing their positions based on the audio signals is also developed All control modes developed are incorporated into a managing system software. The controlling process requires the construction of a digital data interface to the hardware on the basis of the DMX512 protocol. The work includes a detailed description of the DMX512 protocol and the implemented hardware. Final results are illustrated through examples and operation manual / Mestrado / Mecanica dos Sólidos e Projeto Mecanico / Mestre em Engenharia Mecânica
104

Dokumentace části hradu Rokštejn pomocí laserového skenování / Documentation of Roštejn using laser scanning

Vitula, Marek January 2016 (has links)
The goal of this thesis is to scan part of castle Rokštejn using terrestrial laser scanner and from obtained data draw up a 3D model. Model is made with a method using meshing. In this work I also deal with the software, which supports meshing, and evaluating pros and cons of each program. The output of this work is 3D model which will serve to better representation of the current state of the castle and its better documentation.
105

Zaměření specifických prvků v areálu Admas / The surveing of specific elements in the area of Admas

Koukal, Pavel January 2017 (has links)
The diploma thesis consists of two fundamental parts. The first part is focused on scanning a section of the Admas area by a terrestrial laser scanner. This section describes the introduction to laser scanning, necessary utilities and software, fieldwork, the process from the registration of a point cloud, through point cloud processing to its connection into the S-JTSK. The second part of the thesis is mostly focused on execution of the digital model of the relief from the acquired data. It also deals with the two methods of creating a cross-sectional drawing of the area - one is based on the digital model of the relief and the other on data obtained by the polar method. The outcome of the thesis is to assess the accuracy of the topographical model, based on the comparison with the polar method.
106

Digitální model reliéfu v areálu Admas / Digital terrain model in the area of Admas

Kroupa, Ondřej January 2017 (has links)
The goal of this thesis is to scan part of the complex research center AdMaS using terrestrial laser scanner, from obtained data draw up a 3D terrain model and compare the height accuracy with conventional terrestrial measurement. The thesis is focused to software, which allow processing of point clouds and prepare the 3D model. The output of this work is the 3D terrain model and two transverse profiles for vertical comparison of two measurement methods.
107

Robot pro práci ve vnějším terénu / Outdoor Robot

Tomášek, Ondřej January 2008 (has links)
This work deals with navigation of the mobile outdoor robots. It is divided in two parts. In the first part, the mobile robots and their control problem is examined. The technical means for navigation and obstacles avoidance are described and the mathematical means for sensor data fusion and optimal position estimation of the robot are outlined. In the second part the hardware of the robot is described and furthermore it deals with description of the practically realized algorithms for obstacles avoidance and robot navigation.
108

Návrh samosvorného diferenciálu závodního automobilu / Design of limited slip differential of racing engine

Kresta, Vojtěch January 2010 (has links)
The thesis concentrates on the design of limited slip differential of the racing car. It describes the method of designing the model of space for differential, using the 3D ATOS scanner and Pro/ENGINEER software environment. The next part of the thesis illustrates the process of designing the model of mass-produced open differential. The main attention is paid to the design of both versions of clutch limited slip differential and also to the analysis of problematic issues of each analyzed component. Further on, there is a stress analysis of some selected parts: pressure ring, differential case and their comparison before and after their optimization.
109

Detection and counting of Powered Two Wheelers in traffic using a single-plane Laser Scanner / Détection de deux roues motorisées par télémètre laser à balayage

Prabhakar, Yadu 10 October 2013 (has links)
La sécurité des deux-roues motorisés (2RM) constitue un enjeu essentiel pour les pouvoirs publics et les gestionnaires routiers. Si globalement, l’insécurité routière diminue sensiblement depuis 2002, la part relative des accidents impliquant les 2RM a tendance à augmenter. Ce constat est résumé par les chiffres suivants : les 2RM représentent environ 2 % du trafic et 30 % des tués sur les routes.On observe depuis plusieurs années une augmentation du parc des 2RM et pourtant il manque des données et des informations sur ce mode de transport, ainsi que sur les interactions des 2RM avec les autres usagers et l'infrastructure routière. Ce travail de recherche appliquée est réalisé dans le cadre du projet ANR METRAMOTO et peut être divisé en deux parties : la détection des2RM et la détection des objets routiers par scanner laser. Le trafic routier en général contient des véhicules de nature et comportement inconnus, par exemple leurs vitesses, leurs trajectoires et leurs interactions avec les autres usagers de la route. Malgré plusieurs technologies pour mesurer le trafic,par exemple les radars ou les boucles électromagnétiques, il est difficile de détecter les 2RM à cause de leurs petits gabarits leur permettant de circuler à vitesse élevée et ce même en interfile. La méthode développée est composée de plusieurs sous-parties: Choisir une configuration optimale du scanner laser afin de l’installer sur la route. Ensuite une méthode de mise en correspondance est proposée pour trouver la hauteur et les bords de la route. Le choix d’installation est validé par un simulateur. A ces données brutes, la méthode de prétraitement est implémentée et une transformation de ces données dans le domaine spatio-temporel est faite. Après cette étape de prétraitement, la méthode d’extraction nommée ‘Last Line Check (LLC)’ est appliquée. Une fois que le véhicule est extrait, il est classifié avec un SVM et un KNN. Ensuite un compteur est mis en œuvre pour compter les véhicules classifiés. A la fin, une comparaison de la performance de chacun de ces deux classifieurs est réalisée. La solution proposée est un prototype et peut être intégrée dans un système qui serait installé sur une route au trafic aléatoire (dense, fluide, bouchons) pour détecter, classifier et compter des 2RM en temps réel. / The safety of Powered Two Wheelers (PTWs) is important for public authorities and roadadministrators around the world. Recent official figures show that PTWs are estimated to represent only 2% of the total traffic but represent 30% of total deaths on French roads. However, as these estimated figures are obtained by simply counting the number plates registered, they do not give a true picture of the PTWs on the road at any given moment. This dissertation comes under the project METRAMOTO and is a technical applied research work and deals with two problems: detection of PTWsand the use of a laser scanner to count PTWs in the traffic. Traffic generally contains random vehicles of unknown nature and behaviour such as speed,vehicle interaction with other users on the road etc. Even though there are several technologies that can measure traffic, for example radars, cameras, magnetometers etc, as the PTWs are small-sized vehicles, they often move in between lanes and at quite a high speed compared to the vehicles moving in the adjacent lanes. This makes them difficult to detect. the proposed solution in this research work is composed of the following parts: a configuration to install the laser scanner on the road is chosen and a data coherence method is introduced so that the system is able to detect the road verges and its own height above the road surface. This is validated by simulator. Then the rawd ata obtained is pre-processed and is transform into the spatial temporal domain. Following this, an extraction algorithm called the Last Line Check (LLC) method is proposed. Once extracted, the objectis classified using one of the two classifiers either the Support Vector Machine (SVM) or the k-Nearest Neighbour (KNN). At the end, the results given by each of the two classifiers are compared and presented in this research work. The proposed solution in this research work is a propototype that is intended to be integrated in a real time system that can be installed on a highway to detect, extract, classify and counts PTWs in real time under all traffic conditions (traffic at normal speeds, dense traffic and even traffic jams).
110

Within and between session changes in subjective and neuroendocrine stress parameters during magnetic resonance imaging: A controlled scanner training study

Lüken, Ulrike, Mühlhan, Markus, Evens, Ricarda, Wittchen, Hans-Ulrich, Kirschbaum, Clemens January 2012 (has links)
Accumulating evidence suggests that the magnetic resonance imaging (MRI) scanner can act as a stressor, eliciting subjective and neuroendocrine stress responses. Approaches to familiarize subjects with the scanner could help minimizing unintended effects on neural activation patterns of interest. Controlled studies on the effects of a scanner training are however missing. Using a comparative design, we analyzed within- and between session changes in subjective and neuroendocrine stress parameters in 63 healthy, scanner-naïve adults who participated in a two-day training protocol in an MRI, mock, or lab environment. A habituation task was used to assess within-session changes in subjective and neuroendocrine (cortisol) stress parameters; between-session changes were indicated by differences between days. MRI and mock, but not lab training were successful in reducing subjective distress towards the scanner. In contrast, cortisol reactivity towards the training environment generally increased during day 2, and the percentage of cortisol responders particularly rose in the mock and MRI groups. Within-session habituation of subjective arousal and anxiety was observed during both days and irrespective of training condition. Present findings demonstrate that training in a scanner environment successfully reduces subjective distress, but may also induce sensitization of endocrine stress levels during repeated scanning. Subjective distress can further be stabilized by acclimating subjects to the environment prior to the MRI assessment, including a short habituation phase into the assessment protocol. If replicated, present findings should be considered by researchers employing repeated measurement designs where subjects are exposed to a scanner more than once.

Page generated in 0.0501 seconds