L'interférométrie à rétro-injection optique, également connu sous le nom de Self-Mixing, permet de concevoir des capteurs qui sont compacts, auto-alignés et sans contact. Dans ce phénomène, une partie du faisceau laser de retour réfléchi par la cible rentre dans la cavité active de laser et fait varier ses propriétés spectrales. La diode laser agit alors comme une source de lumière, un microinterféromètre ainsi qu'un détecteur de lumière. Dans cette thèse, un capteur de déplacement, basé sur la rétro-injection optique, a été optimisé de sorte que des mesures précises peuvent être obtenues en temps réel. Le capteur est robuste à la disparition des franges de self-mixing pour des vibrations harmoniques. Il est également capable de s'adapter à un changement dans le régime de feedback optique et peut donc extraire le déplacement dans les cas les plus répandus expérimentalement, à savoir un feedback faible puis modéré. L'utilisation de l'optique adaptative, sous la forme d'une lentille liquide, a également été démontrée pour ce capteur, ce qui nous a permis de maintenir le capteur dans un régime de feedback favorable. L'influence du speckle a également été réduite de telle sorte que le capteur mesure jusqu'à la gamme centimétrique pour des cibles non- oopératives. Une nouvelle technique est également présentée, elle permet de rendre le capteur insensible aux vibrations mécaniques parasites qui fausseraient la mesure pour des conditions industrielles. / Optical Feedback Interferometry, also known as Self-Mixing, results in compact, selfaligned and contact-less sensors. In this phenomenon, a portion of the laser beam is back reflected from the target and enters the active laser cavity to vary its spectral properties. The laser diode then simultaneously acts as a light source, a micro- nterferometer as well as a light detector. In this thesis, a self-mixing displacement sensor has been optimised so that precise measurement can be obtained in real-time. The sensor is robust to the disappearance of self-mixing fringes for harmonic vibrations. It is also able to auto-adapt itself to a change in the optical feedback regime and so can extract displacement from the weak as well as moderate feedback regime signals. The use of adaptive optics, in the form of a liquid lens, has also been demonstrated for this sensor, which has allowed us to maintain the sensor in a fringe-loss less regime. The influence of speckle has also been reduced so that the sensor can now measure up to the centimetric range for non-cooperative targets. A novel technique has also been presented that makes the sensor insensitive to parasitic mechanical vibrations that would falsify the measurement under industrial conditions.

Les travaux présentés dans cette thèse concernent l’utilisation de données de télédétection inédites pour le suivi des glaciers du massif du Mont Blanc : les images radar à synthèse d’ouverture Haute Résolution (HR) du satellite TerraSAR-X et les prises de vue HR d’un appareil photo numérique automatique. Cette thèse s’attache à montrer l’apport de ces sources d’informations hétérogènes pour mesurer le déplacement de surface des glaciers alpins. Dans cette optique, un examen des méthodes de mesure de déplacement spécifiques à chacun des deux types d’images est réalisé. Deux approches sont alors explorées : la mesure de déplacement monosource dans la géométrie propre à chaque capteur et la mesure de déplacement multisource via des combinaisons intra-capteur et inter-capteur. Alors que l’approche monosource fournit uniquement des mesures 2D du déplacement, les mesures multisources permettent pour la première fois d’estimer des champs de déplacement 3D de la surface des glaciers du Mont Blanc. Les mesures ont été réalisées sur plusieurs séries temporelles d’images couvrant la période 2008-2009 pour quatre glaciers du massif du Mont Blanc (Argentière, Mer de Glace/Leschaux, Bossons et Taconnaz). Dans le contexte du changement climatique, ces mesures de déplacement de surface fournissent une donnée intéressante en glaciologie pour contraindre les modèles numériques d’écoulement et d’évolution des glaciers. / The works presented in this PhD thesis focuses on the use of new remote sensing data for "massif du Mont Blanc" glaciers’ monitoring: High Resolution (HR) synthetic aperture radar images of TerraSAR-X satellite and HR shooting of the automatic digital camera. This thesis will show the contribution of this heterogeneous information to the measurement of the surface displacement of alpine glacier. For this purpose, a review of displacement measurement methods specific to each of the two types of image is proposed. Then two approaches are explored: the mono-source displacement measurement in the geometry for each sensor and the multi-source displacement measurement via intra-sensor and inter-sensor combinations. While the mono-source approach provides only 2D displacement measurements, multi-source measurements allow, for the first time, the estimation of 3D surface displacement fields of the Mont Blanc glaciers. The measurements were performed on several image time series covering the period 2008-2009 for four Mont Blanc glaciers (Argentière, Mer de Glace/Leschaux, Bossons et Taconnaz). In the context of global warming, these surface displacement measurements provide interesting data in the glaciology domain in order to constrain flow and evolution digital models.

An electrostatic actuator driven by conventional voltage control and charge control requires high actuation voltage and suffers from the pull-in phenomenon that limits its operation range, much less than its entire gap. To provide effective solutions to these problems, we present complete analytical and numerical models of various electrostatic actuators coupled with resonant drive circuits that are able to drive electrostatic actuators at much lower input voltage than that of conventional actuation methods and to extend their operation range beyond their conventional pull-in points in the presence of high parasitic capacitance. Moreover, in order to validate the analytical and numerical models of various electrostatic actuators coupled with the resonant drive circuits, we perform the experiment on the microplate and the micromirror coupled with the resonant drive circuit. For instance, using a high voltage amplifier, we manage to rotate the micromirror with sidewall electrodes by 6 ° at 180 V. However, using the resonant drive circuit, we are able to rotate the same micromirror by 6 ° at much lower input voltage, 8.5 V. In addition, the presented work also facilitates the stability analysis of electrostatic actuators coupled with the resonant drive circuits and provides how the effect of the parasitic capacitance can be minimized. For example, the resonant drive circuit placed within a positive feedback loop of a variable gain amplifier is able to extend the operation range much further even in the presence of very high parasitic capacitance. The resonant drive circuit with the proposed feedback controllers is also able to minimize the detrimental effects of the parasitic capacitance and to displace a parallel-plate actuator over its entire gap without the saddle-node bifurcation. Finally, we present a new displacement measurement method of electrostatic actuators coupled with the resonant drive circuits by sensing the phase delay of an actuation voltage with respect to an input voltage. This new measurement method allows us to easily implement feedback control into existent systems employing an electrostatic actuator without any modification or alteration to the electrostatic actuator itself. Hence, this research work presents the feasibility of electrostatic actuators coupled with the resonant drive circuit in various industrial and medical applications, in which the advantages of miniaturization, low supply voltage, and low power consumption are greatly appreciated.

An electrostatic actuator driven by conventional voltage control and charge control requires high actuation voltage and suffers from the pull-in phenomenon that limits its operation range, much less than its entire gap. To provide effective solutions to these problems, we present complete analytical and numerical models of various electrostatic actuators coupled with resonant drive circuits that are able to drive electrostatic actuators at much lower input voltage than that of conventional actuation methods and to extend their operation range beyond their conventional pull-in points in the presence of high parasitic capacitance. Moreover, in order to validate the analytical and numerical models of various electrostatic actuators coupled with the resonant drive circuits, we perform the experiment on the microplate and the micromirror coupled with the resonant drive circuit. For instance, using a high voltage amplifier, we manage to rotate the micromirror with sidewall electrodes by 6 ° at 180 V. However, using the resonant drive circuit, we are able to rotate the same micromirror by 6 ° at much lower input voltage, 8.5 V. In addition, the presented work also facilitates the stability analysis of electrostatic actuators coupled with the resonant drive circuits and provides how the effect of the parasitic capacitance can be minimized. For example, the resonant drive circuit placed within a positive feedback loop of a variable gain amplifier is able to extend the operation range much further even in the presence of very high parasitic capacitance. The resonant drive circuit with the proposed feedback controllers is also able to minimize the detrimental effects of the parasitic capacitance and to displace a parallel-plate actuator over its entire gap without the saddle-node bifurcation. Finally, we present a new displacement measurement method of electrostatic actuators coupled with the resonant drive circuits by sensing the phase delay of an actuation voltage with respect to an input voltage. This new measurement method allows us to easily implement feedback control into existent systems employing an electrostatic actuator without any modification or alteration to the electrostatic actuator itself. Hence, this research work presents the feasibility of electrostatic actuators coupled with the resonant drive circuit in various industrial and medical applications, in which the advantages of miniaturization, low supply voltage, and low power consumption are greatly appreciated.

L’observation de la Terre par des systèmes d’acquisition d’images permet de suivre l’évolution temporelle de phénomènes naturels tels que les séismes, les volcans ou les mouvements gravitaires. Différentes techniques existent dont l’imagerie satellitaire, la photogrammétrie terrestre et les mesures in-situ. Les séries temporelles d’images issues d’appareils photo automatiques (Time Lapse) sont une source d’informations en plein essor car elles offrent un compromis intéressant en termes de couverture spatiale et de fréquence d’observation pour mesurer les déplacements de surface de zones spécifiques. Cette thèse est consacrée à l’analyse de séries d’images issues de la photographie terrestre et de l’imagerie radar satellitaire pour la mesure du déplacement des glaciers Alpins. Nous nous intéressons en particulier aux problèmes du traitement de Time Lapse stéréo pour le suivi d’objets géophysiques dans des conditions terrain peu favorables à la photogrammétrie. Nous proposons une chaîne de traitement mono-caméra qui comprend les étapes de sélection automatique des images, de recalage et de calcul de champs de déplacement bidimensionnel (2D). L’information apportée par les couples stéréo est ensuite exploitée à l’aide du logiciel MICMAC pour reconstruire le relief et obtenir le déplacement tridimensionnel(3D). Plusieurs couples d’images radar à synthèse d’ouverture (SAR) ont également été traités à l’aide des outils EFIDIR pour obtenir des champs de déplacement 2D dans la géométrie radar sur des orbites ascendantes ou descendantes. La combinaison de mesures obtenues quasi-simultanément sur ces deux types d’orbites permet de reconstruire le déplacement 3D. Ces méthodes ont été mises en oeuvre sur des séries de couples stéréo acquis par deux appareils photo automatiques installés sur la rive droite du glacier d’Argentière et sur des images du satellite TerraSAR-X couvrant le massif du Mont-Blanc. Les résultats sont présentés sur des données acquises lors d’une expérimentation multi-instruments menée en collaboration avec l’IGN à l’automne 2013, incluant le déploiement d’un réseau de Géocubes qui ont fournit des mesures GPS. Elles sont utilisées pour évaluer la précision des résultats obtenus par télédétection proximale et spatiale sur ce type de glacier. / Earth observation by image acquisition systems allows the survey of temporal evolution of natural phenomena such as earthquakes, volcanoes or gravitational movements. Various techniques exist including satellite imagery, terrestrial photogrammetry and in-situ measurements. Image time series from automatic cameras (Time Lapse) are a growing source of information since they offer an interesting compromise in terms of spatial coverage and observation frequency in order to measure surface motion in specific areas. This PhD thesis is devoted to the analysis of image time series from terrestrial photography and satellite radar imagery to measure the displacement of Alpine glaciers. We are particularly interested in Time Lapse stereo processing problems for monitoring geophysical objects in unfavorable conditions for photogrammetry. We propose a single-camera processing chain that includes the steps of automatic photograph selection, coregistration and calculation of two-dimensional (2D) displacement field. The information provided by the stereo pairs is then processed using the MICMAC software to reconstruct the relief and get the three-dimensional (3D) displacement. Several pairs of synthetic aperture radar (SAR) images were also processed with the EFIDIR tools to obtain 2D displacement fields in the radar geometry in ascending or descending orbits. The combination of measurements obtained almost simultaneously on these two types of orbits allows the reconstruction of the 3D displacement. These methods have been implemented on time series of stereo pairs acquired by two automatic cameras installed on the right bank of the Argentière glacier and on TerraSAR-X satellite images covering the Mont-Blanc massif. The results are presented on data acquired during a multi-instrument experiment conducted in collaboration with the French Geographic National Institute (IGN) during the fall of 2013,with a network of Géocubes which provided GPS measurements. They are used to evaluate the accuracy of the results obtained by proximal and remote sensing on this type of glacier.

Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-11-30Bitstream added on 2014-06-13T20:49:10Z : No. of bitstreams: 1 takiy_ae_me_ilha.pdf: 1702331 bytes, checksum: b89d2b4960ee7bbc0e01a3a5d3e7a2be (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Neste trabalho estuda-se a interferometria laser, a qual constitui uma técnica adequada para determinar grandezas físicas com sensibilidade extremamente elevada. Basicamente, no interferômetro óptico, a informação a respeito do dispositivo sob teste é inserida na fase da luz. Utilizando-se o fotodiodo, promove-se a transferência de informação, do domínio óptico para o elétrico, no qual pode ser demodulada usando-se as várias técnicas disponíveis na literatura para detectar sinais modulados em fase. Ênfase é dada a um novo método de demodulação de fase óptica auto-consistente e de grande sensibilidade. Neste método, utiliza- se a modulação dada por uma forma de onda triangular e é baseado na análise do espectro do sinal fotodetectado, sendo capaz de estender a faixa dinâmica de demodulação a valores tão elevados quanto às dos métodos clássicos. Simulações dinâmicas computacionais de interferômetros ópticos são executadas em Simulink juntamente com este método, levando-se em consideração tensões de ruído eletrônico do tipo ruído branco, evidenciando a eficiência do método quando comparados com dados teóricos obtidos em Matlab. A validação experimental do método é realizada com o auxílio de um modulador eletro-óptico de amplitudes, cujas características de fase podem ser previstas analiticamente. Trata-se de um sensor polarimétrico baseado em cristal de Niobato de Lítio, em que a diferença de fase óptica induzida pela tensão elétrica aplicada pode ser determinada através de análise espectral, tal como o novo método descrito neste trabalho. Um interferômetro de Michelson homódino de baixo custo é implementado e a eficiência do novo método de demodulação de fase óptica é avaliada através de testes com atuadores e manipuladores piezoelétricos flextensionais, cujas características de linearidade são conhecidas... / In this work, has been done a study the laser interferometer, which is a technique for determining physical quantities with extremely high sensitivity. Basically, in the optical interferometer, information about the device under test modulates the phase of light. Using a photodiode, promotes the transfer of information from the optical domain for the electric, which can be demodulated using the various techniques available in literature to detect modulated signals in phase. Emphasis is given to a new method of phase demodulation of optical self-consistent and high sensitivity. The method employs a linear modulation given by a triangular waveform, and is based on analysis of the spectrum of the photodetected signal, being able to extend the dynamic range of the demodulation values as high as the classical methods. Dynamic computational simulations of optical interferometers are implemented in Simulink with this method, taking into account strains of electronic noise like white noise, indicating the efficiency of the method compared with theoretical data obtained in Matlab workspace. The experimental validation of the method is performed with the aid of an electro- optic amplitude modulator, whose phase characteristics can be analytically predicted. This is a polarimetric sensor based on lithium niobate crystal, in which the optical phase difference induced by electric voltage can be determined by spectral analysis, using new method described in this work. A low cost homodyne Michelson interferometer is implemented and the efficiency of the new method of optical phase demodulation is evaluated by testing with piezoelectric flextensional actuators whose characteristics of linearity are well known.The experimental results agree with theoretical analysis and reveal this method is more efficient than the classical methods

This thesis is focused on measurement and analysis of dynamic effects on railway turnouts. Two same-type turnouts with different fastening elasticity were chosen. My attention was focused mainly on the crossing part of the turnout, where the highest dynamic impacts occur. The point of the thesis is comparison of the crossing part of turnouts in term of dynamic behaviour and assessment of influence of soft rail pads on spread of dynamic energy through the construction. A part of the thesis is choice of methodology of the measurement and proposal of convenient mathematical apparatus for analysing of the dynamic effects on crossings.

Orientador: Cláudio Kitano / Resumo: Nesta dissertação de mestrado é apresentado um vibrômetro para a medição de deslocamentos nanométricos. O vibrômetro proposto está baseado em um interferômetro de Michelson modificado, homódino e em malha fechada. A demodulação em tempo real é executada inteiramente em modo digital, utilizando uma plataforma embarcada que realiza a aquisição de dados, processamento dos sinais, controle PI (proporcional-integral) e a geração dos sinais que acionam o modulador de fase óptica (baseado em uma célula Pockels) e o atuador piezoelétrico sob estudo. Dois sinais em quadratura de fase são obtidos a partir de um único sinal interferométrico utilizando uma tensão de modulação principal e, em seguida, a conhecida técnica de multiplicação cruzada é aplicada para calcular a variação da fase óptica de interesse. A condição de quadratura é atingida pelo próprio controlador PI por meio da análise da figura de Lissajous dos sinais fora de fase. O novo vibrômetro óptico é capaz de medir deslocamentos nanométricos, e é simples, barato, exato, imune ao desvanecimento e auto-consistente. O controlador PI é robusto, uma vez que o método de demodulação é capaz de trabalhar com elevado ruído eletrônico, variações indesejáveis no ganho do amplificador e na tensão de meia-onda da célula Pockels com a temperatura e outras perturbações externas. O novo sistema foi utilizado para determinar a magnitude da resposta em frequência de dois protótipos de atuadores piezoelétricos flextensionais multiatuados. As ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A vibrometer to measure nanometric displacements is presented in this work. The proposed vibrometer is based on a modified closed loop homodyne Michelson interferometer. Real-time phase demodulation is carried out entirely in a digital mode, using an embedded platform that performs data acquisition, signal processing, PI (proportional-integral) control and the generation of signals that drive the electrooptic Pockels cell phase shifter and the piezoelectric actuator under test. Two phase quadrature signals are generated from a single interferometric output, using the interleaving action, in alternation, of a digitally generated principal modulating signal, and then the well-known cross-multiplication technique is applied to perform the computation of the phase shift of interest. The quadrature condition is reached by the PI control itself, using the length difference between the major axis and the minor axis of the ellipse formed by the Lissajous figure associated with the out of phase signals as the controller error signal. The new optical vibrometer is capable of measuring nanometric displacements, and is simple, inexpensive, accurate, immune to fading and self-consistent. The PI controller is robust, since the demodulation method is able to work under high electronic noise, undesirable variations in Pockels cell half-wave voltage with temperature, amplifier gain and other external entrances. The new method was used to determine the displacement frequency response curves of... (Complete abstract click electronic access below) / Mestre

The great social and economic impact of earthquakes has made necessary the development of novel structural health monitoring (SHM) solutions for increasing the level of structural safety and assessment. SHM is the process of comparing the current state of a structure’s condition relative to a healthy baseline state to detect the existence, location, and degree of likely damage during or after a damaging input, such as an earthquake. Many SHM algorithms have been proposed in the literature. However, a large majority of these algorithms cannot be implemented in real time. Therefore, their results would not be available during or immediately after a major event for urgent post-event response and decision making. Further, these off-line techniques are not capable of providing the input information required for structural control systems for damage mitigation. The small number of real-time SHM (RT-SHM) methods proposed in the past, resolve these issues. However, these approaches have significant computational complexity and typically do not manage nonlinear cases directly associated with relevant damage metrics. Finally, many available SHM methods require full structural response measurement, including velocities and displacements, which are typically difficult to measure. All these issues make implementation of many existing SHM algorithms very difficult if not impossible. This thesis proposes simpler, more suitable algorithms utilising a nonlinear Bouc-Wen hysteretic baseline model for RT-SHM of a large class of nonlinear hysteretic structures. The RT-SHM algorithms are devised so that they can accommodate different levels of the availability of design data or measured structural responses, and therefore, are applicable to both existing and new structures. The second focus of the thesis is on developing a high-speed, high-resolution, seismic structural displacement measurement sensor to enable these methods and many other SHM approaches by using line-scan cameras as a low-cost and powerful means of measuring structural displacements at high sampling rates and high resolution. Overall, the results presented are thus significant steps towards developing smart, damage-free structures and providing more reliable information for post-event decision making.

L'interaction entre un faisceau laser émis avec une partie de la lumière réfléchi depuis une cible qui rentre dans la cavité active du laser, est à l'origine du phénomène de rétro-injection optique ou self-mixing. L'utilisation de ces franges interférométriques non conventionnelles, semble attractive du au faible nombre des composant optiques et son caractère auto-aligné. Dans cette thèse nous approchons leur développement en tant qu'implémentation embarqué rentable pour la mesure du déplacement. A cette fin, nous avons exploré des méthodes du traitement du signal pour la détection des franges et la reconstruction du mouvement de la cible, en évitant l'usage de composant externes. Premièrement, nous avons identifié quelques incompatibilités dans des algorithmes précédentes établis dans notre centre de recherche, puis nous avons avancé des solutions. Fondé sur la théorie d'interpolation, an algorithme simplifié mais démontré convenable en temps-réel à été proposé pour la reconstruction du déplacement. En s'appuyant sur l'élaboration d'un signal analytique, il à été proposé une version amélioré pour le calcul de phase. Celle-ci nous à permit de fournir un algorithme pour la détection de franges, robuste aux variations d'amplitude, sans tenir compte du régime de rétro-injection, impliquant une convenable utilisation pour une variété d'applications. / The interaction between an emitted laser beam and a small portion of backscattered light from a pointed target that re-enters the laser's cavity, is at the origin of optical feedback phenomenon or self-mixing. Exploiting these unconventional interferometric fringes for non-contact sensors is attractive due to its minimal optical part-count and self-aligned nature. In this thesis we approach its development as a cost-eective embedded implementation for displacement measurement. To this end we explored signal processing methods for fringe detection and target's movement reconstruction, avoiding the usage of external components. We first identified some incompatibilities in prior algorithms from our research center, and then proposed further solutions. Based on interpolation theory, a simplified but proved real-time algorithm resulted for displacement reconstruction. Relying on analytical signal elaboration, an improved approach for phase calculation allowed us to provide a fringe detection algorithm robust to amplitude variations, disregarding the feedback regime and thus, allowing a seemly usage over an increased variety of applications.