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  • 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.
21

Sistema de estabilização de vídeo baseado em acelerômetro, filtragem robusta e algoritmo de busca de três etapas / Video stabilization system based on accelerometer, robust filtering and three-step search algorithm

Ayrton Galindo Bernardino Florêncio 17 September 2015 (has links)
Câmeras embarcadas em sistemas robóticos móveis com sensoriamento visual geralmente são afetadas pelo movimento de seu suporte quando é necessária a aquisição de imagens com alta confiabilidade. Algumas câmeras disponíveis no mercado já estão equipadas com sistemas de estabilização de imagens, implementados nas lentes da câmera ou no sensor de imagem. Esses sistemas são relativamente caros para serem instalados em sistemas robóticos móveis aéreos ou terrestres de pequeno porte. Outro conceito que tem sido utilizado para alcançar a estabilização consiste em adotar sensores inerciais, algoritmos de visão computacional e aplicação de filtros digitais para estimativa e suavização de movimento. Esta dissertação tem por finalidade apresentar um sistema de estabilização digital de vídeo em conjunto com um acelerômetro para detectar movimentos da câmera. Considera-se que a câmera está instalada sobre plataforma instável ou em veículo em movimento, assim, utiliza-se filtragem robusta para minimizar o efeito da vibração sobre a câmera. Vários experimentos são realizados adicionando vibração em vídeo por meio de simulações em computador. Considera-se também experimentos em ambiente real com a câmera montada em um suporte dentro de um veículo em movimento. A principal contribuição deste trabalho é a realização de um estudo comparativo para analisar a vantagem de se usar uma abordagem robusta entre os métodos de filtragem comumente utilizados em sistemas de estabilização de vídeo. / Embedded cameras in robotic systems usually are susceptible to movements of your basis. The measurements can be affected mainly when they should obtain high performance in actual applications. Although some cameras available on the market are already equipped with an optical image stabilization system, implemented either in the camera lenses or in the image sensor. They are usually expensive to be installed into small aerial or land robotic systems. This dissertation presents a video stabilization system coupled with an accelerometer for motion detection at an unstable platform. It is embedded in a vehicle. Robust filtering is used to minimize vibration effects on the camera. Several experiments were performed, adding either vibrations via computer simulations and taking images from the camera with the vehicle moving. The main contribution of this work is the accomplishment of a comparative study to analyse the advantages of applying a robust approach among others filtering methods that frequently are used to video stabilizing systems.
22

Étude du bruit des accéléromètres électrostatiques ultrasensibles de la mission GOCE. / A study of the measurement noise of the ultrasensitive electrostatic accelerometers integrated in the satellite of the mission GOCE

Chen, Raphaël 13 February 2017 (has links)
L'instrument principal de la mission GOCE est un gradiométre triaxial contenant 6 paires d'accéléromètres électrostatiques ultrasensibles conçus par l'ONERA. chaque accéléromètre est constitue d'une masse d'épreuve entourée par 8 paires d'électrodes permettant de la contrôler en position grâce a une boucle d'asservissement électronique. il est possible de recombiner les mesures accélérométriques pour en déduire les composantes du gradient de gravite. il s'agit de la grandeur fondamentale d'intérêt dans la mission GOCE. malgré son succès, la communauté scientifique s'est aperçue que le bruit contenu dans le terme vzz est 2 fois plus élevés que prévu. ce niveau de bruit est reste inexpliqué. la qualité des données GOCE dépend directement de celle des mesures accélérométriques. l'ONERA détenant l'expertise sur la technologie des accéléromètres électrostatiques ultrasensibles, une étude approfondie au plus proche de l'instrument s'est avérée nécessaire. dans un premier temps, une méthode d'estimation d'un majorant du niveau de bruit empirique des mesures accélérométriques est proposée a partir de la différence des modes communs. dans un second temps, ces estimations a partir des données empiriques sont reliées aux sources de bruit. en prenant en compte les sources de bruit qui ont été vérifiées, on a analyse deux scenarios qui pourraient aboutir au niveau empirique du bruit total de mesure. enfin, on a identifie que le bruit du facteur d'échelle n'a pas été inclus dans le calcul du niveau de bruit attendu. on montre que, dans le cas des axes de mesure sensible, la prise en compte du bruit de facteur d'échelle aboutit a l'augmentation du niveau de bruit de mesure attendu. / The payload of the space mission goce is a 3 axis gradiometer containing 6 ultrasensitive electrostatic accelerometers designed by onera – the french aerospace lab. each accelerometer contains a proof mass surrounded by 8 pairs of electrodes allowing the control of its position thanks to a feedback control loop. the recombination of the accelerometer measurements leads to the estimation of the terms of the gravity gradient matrix. it is the target quantity of the mission goce. despite the success of the mission, the scientific community discovered that the noise level of the term vzz is twice as high as the level expceted. this remains unexplained. the quality of the data is directly related to the quality of the accelerometer measurements. because onera has the expertise on the accelerometer technology, an in-depth study proved to be necessary. we first provide a way to estimate an upper bound of the empirical noise in the measurements. then, we analyse two scenarios that could lead to the empirical noise observed. finally, we show that taking into account the scale factor noise leads to a higher noise than expected.
23

Automatická kalibrace inerciálních senzorů / Automatic calibration of inercial sensors

Hamada, Vladimír January 2014 (has links)
The main aim of this thesis is to design and build automatic calibration system for inertial measurement sensors. The calibration system is intended to support the development of devices with inertial measurement sensors. The great emphasis is placed on the configurability of system and for this reason all calculations are realized by Matlab system, which is well known by engineers. There is also presented design of inertial measurement unit, which is used as a~model sensor unit for calibration system development.
24

Univerzální platforma pro měření inerciálních a tlakových senzorů / Universal platform for measurement of inertial and pressure sensors

Usnul, Jan January 2017 (has links)
Author describes the creation of software for the initial sensor test platform and controll computer. The platform can measure inertial and pressure sensors regardless their specific type. Measurement is provided by automatic test which is defined by the user. Also, the author describes the creation and implementation of communication protocols between control software (on Windows platform) and test platform (embedded C).
25

慣性センサを用いた手指の運動計測に関する研究 / カンセイ センサ オ モチイタ テユビ ノ ウンドウ ケイソク ニカンスル ケンキュウ

北野 敬祐, Keisuke Kitano 22 March 2019 (has links)
身体運動計測の重要性は増してきているが,作業で必須となる手指運動を精度良く計測することは困難である.本論文の目的は,手指運動計測システムを開発し,高精度な手指運動計測および解析手法を構築することである.そのため,手指運動計測用の慣性センサシステムを開発し,それに適した手指モデルの構築手法,計測誤差補正手法を提案,適用することで,より動作制約のない手指運動を精度良く計測,解析可能とする手法を構築した. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University
26

Fjärrkontrollstyrd sampling av tröghetssensorer / Remote controlled samplning of inertial sensors

Karlberg, Nicholas January 2019 (has links)
På avdelningen Medicinsk Teknik-Forskning och Utveckling på Norrlands Universitetssjukhus (MT-FoU) pågår en utveckling av ett rörelsemätsystem (MoLab) som syftar till att ge kvantitativa data från individer med nedsatt rörelsefunktion. Denna information kan fungera som underlag för behandling och användas för att utvärdera uppföljning av behandlingar. Mätsystemet begränsas idag av att det är beroende av en accesspunkt med tillhörande lokalt nätverk för att föra över data till insamlingsdator via TCP/IP-protokollet.   Examensarbetet syftar till att öka mätsystemets mobilitet genom att inkludera en portabel och trådlös mätlösning utan krav på stationär accesspunkt och insamlingsdator vid insamlingstillfället. Med ett mer mobilt mätsystem kan data inhämtas från individer i dennes autentiska och vardagliga miljö.   En lokal lagringsyta har kopplats till sensorenheterna och användargränssnittet utgörs istället av en fjärrkontroll, som startar och stoppar mätningar. Fjärrkontrollen fungerar också som en accesspunkt som sensorenheterna ansluter till och som vidarebefordrar start- och stoppsignaler via UDP-broadcast från fjärrkontroll till alla uppkopplade sensorenheter. Vid given stoppsignal överförs sensordata till fjärrkontrollen för efterföljande lagring på dess interna minneskort. Det är viktigt att mätningarna sker synkront mellan sensorenheterna, där startsynkroniseringen kan kvantifieras som tidsdifferensen mellan sensorenheternas mätstart.  Med metoden som föreslås i detta arbete, hamnar startsynkroniseringen väl under ett väldefinierat tröskelvärde på 2 ms som också fanns implementerat i MoLab och är därför en tänkbar metod för att utöka mobiliteten för MoLab. / The department of Biomedical Engineering Research and Development at University Hospital (MT-FoU) is developing a motion measurement system (MoLab) that aims to provide quantitative data from individuals with impaired mobility. This information can serve as a basis for treatments and used to evaluate follow-up of treatments. The measuring system is today limited by the fact that it is dependent on an access point and associated local network to communicate data to an evaluation computer via the TCP/IP protocol. This is a bachelor thesis that aims to give this measuring system greater freedom to measure without dependence of a stationary access point and evaluation computer. With a more mobile system, data can be obtained in a more authentic and everyday environment for the individuals to be measured.  An internal memory has been connected to the inertial sensor devices, and the user interface is instead a remote control, which starts and stops measurements. The remote-control acts as the access point which the sensor devices connects to and start and stop signals are transmitted via UDP broadcast from the remote-control to the sensor devices. In case of a given stop signal, sensor data is transferred to the internal memory of the remote control. It is important that the measurements take place synchronously where the synchronization can be quantified as the time difference between the sensor devices at the measurement start. With this method, start synchronization ends up well below a well-defined threshold value of 2 ms that was also implemented in MoLab, giving it greater mobility.
27

Propagation of atoms in a magnetic waveguide on a chip / Propagation d'atomes dans un guide magnétique sur puce

Bade, Satyanarayana 18 November 2016 (has links)
Dans cette thèse, nous étudions la propagation des atomes dans un guide magnétique toroïdal, dans le but de développer un capteur inertiel. Ici, nous présentons différentes stratégies pour créer un guide sur une puce atomique pour un interférometre Sagnac atomique guidé. Nous avons mis au point trois solutions qui peuvent être realisé avec la même configuration des fils. Ils utilise la technique de modulation de courant avec un nouveau point de vue qui traite simultanément la problème de rugosité des fils et les pertes de Majorana dépendant du spin. L'effect de la propagation multimode des atomes dan le guide est aussi quantifié dans cette thèse. En utilisant un modèle simple, nous avons couvert les cas de la propagation de gaz non interactif ultra froids et thermique. Nous avons identifié les conditions operationelles pour realiser un interferometre à atomes froids avec une grande gamme dynamique, essentielle pour les application en navigation inertielle. Expérimentalement, cette thèse decrit la réalisation et la characterisation de la source atomes froids proche d'un substrat avec un dépôt d'or, ainsi que l'implémentation et la caracterisation des systèmes de détection. / In this thesis we study the propagation of atoms in a magnetic toroidal waveguide, with the aim of developing an inertial sensor. Here, we present different strategies to create the waveguide on an atom chip for a guided Sagnac atom interferometer. We devised three solutions which can be achieved using the same wire configuration. They use the current modulation technique, from a new point of view, which simultaneously tackles the problem of wire corrugation and spin dependent Majorana atom losses. The effect of the multimode propagation of the atoms in the guide is also quantified in this thesis. Using a simple model, we covered the propagation of noninteracting ultracold and thermal gases. We identified the operating conditions to realize a cold atom interferometer with a large dynamic range essential for applications in inertial navigation. Experimentally, the thesis describes the realisation and characterisation of the cold atom source close to a gold coated substrate, as well as the implementation and the characterisation of the atom detection systems.
28

State Estimation and Limited Communication Control for Nonlinear Robotic Systems

Rehbinder, Henrik January 2001 (has links)
No description available.
29

Low noise, low power interface circuits and systems for high frequency resonant micro-gyroscopes

Dalal, Milap 03 July 2012 (has links)
Today's state-of-the-art rate vibratory gyroscopes use a large proof mass that vibrates at a low resonance frequency (3-30 kHz), a condition that creates a performance tradeoff in which the gyroscope can either offer large bandwidth or high resolution, but not both. This tradeoff led to the development of the capacitive bulk acoustic wave (BAW) silicon disk gyroscope, a new class of micromachined rate vibratory gyroscopes operating in the frequency range of 1-10MHz with high device bandwidth and shock/vibration tolerance. By scaling the frequency, BAW gyroscopes can provide low mechanical noise without sacrificing the high bandwidth performance needed for most commercial applications. The drive loop of the BAW gyroscope can also be exploited as a timing device that can be integrated in existing commercial systems to provide competitive clock performance to the state-of-the-art using less area and power. This dissertation discusses the design and implementation of a CMOS ASIC architecture that interfaces with a high-Q, wide-bandwidth BAW gyroscope and the challenges associated with optimizing the noise performance to achieve navigation-grade levels of sensitivity as the frequency is scaled into the MHz regime. Mathematical models are derived to describe the operation of the sensor and are used to generate equivalent electrical circuit models of the gyroscope. A design strategy is then outlined for the ASIC to optimize the drive loop and sense channel for power and noise, and steps toward reducing this noise as the system is pushed to navigation-grade performance are presented that maintain optimum system power consumption. After analyzing the BAW gyroscope and identifying a strategy for developing the drive and sense interface circuitry, a complete fully-differential ASIC is designed in 0.18μm CMOS to interface with a bulk acoustic wave (BAW) disk gyroscope. As an oscillator, the gyroscope provides an uncompensated clock signal at ~9.64 MHz with a temperature sensitivity of -27 ppm/°C and phase noise of -104 dBc at 1 kHz from carrier. When the complete ASIC is interfaced with the gyroscope, the sensor shows a measured rate sensitivity of 1.15 mV/o/s with an open-loop bandwidth of 280 Hz and a bias instability of 0.095 o/s, suitable for the rate-grade performance commonly required for commercial and consumer electronics applications. The system is recorded to have a total power of 1.6 mW and a total area of 0.64 mm2. Following the design of the interface ASIC, this dissertation investigates in further detail the requirements for designing and optimizing charge pumps for capacitive MEMS devices. Basic charge pump design is outlined, followed by an overview of techniques that can be used to generate larger polarization voltages from the ASIC. Lastly, an alternate measurement technique for measuring the rotation rate of the gyroscope is discussed. This technique is based on the phase-shift modulation of the gyroscope output signal when the device is driven with two orthogonal signal inputs and can be easily modified to provide either linear scale factor measurement or a linear calibration curve that can be used to track and adjust the variation of the sensor scale factor over time.
30

State Estimation and Limited Communication Control for Nonlinear Robotic Systems

Rehbinder, Henrik January 2001 (has links)
No description available.

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