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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.
11

Online Calibration of Camera Roll Angle / Dynamisk kalibrering av kamerarollvinkeln

de Laval, Astrid January 2013 (has links)
Modern day cars are often equipped with a vision system that collects informa- tion about the car and its surroundings. Camera calibration is extremely impor- tant in order to maintain high accuracy in an automotive safety applications. The cameras are calibrated offline in the factory, however the mounting of the camera may change slowly over time. If the angles of the actual mounting of the cam- era are known compensation for the angles can be done in software. Therefore, online calibration is desirable. This master’s thesis describes how to dynamically calibrate the roll angle. Two different methods have been implemented and compared.The first detects verti- cal edges in the image, such as houses and lamp posts. The second one method detects license plates on other cars in front of the camera in order to calculate the roll angle. The two methods are evaluated and the results are discussed. The results of the methods are very varied, and the method that turned out to give the best results was the one that detects vertical edges.
12

An alternative gyroscope calibration methodology

Du Plessis, Jan Abraham Francois 25 November 2013 (has links)
D.Ing. (Electrical & Electronic Engineering Science) / The objective of the research performed in this thesis is to address the calibration process of Fiber-Optic Gyroscopes (FOGs) - a class of gyroscopes that make use of the Sagnac effect to determine rotational information from laser-light traveling in an optical fiber. The calibration process has traditionally been a time-consuming and therefore an expensive one due to the various environmental parameters that can influence the sensor under operation. Calibration is not a step that can be neglected as it is the process whereby the residual manufacturing errors in the sensor are characterized. If these measurement errors are not eliminated, the sensors would result in the host vehicle's assumed position rapidly diverging from its true position. Once the errors are characterized, they can be removed from the sensor output to improve the accuracy of the complete navigation system. The class of the sensor is determined by the amount of residual errors and the smaller the residual errors, the more expensive the sensor. The specific focus of the study is to determine whether it is possible to reduce the calibration cost of the Fiber-Optic Gyroscopes through the use of innovative calibration strategies. The use of neural networks are investigated as an alternative to the traditional calibration strategies which consists of the estimation of the constant error parameters through stochastic estimation strategies such as Kalman filters. The whole calibration problem is recast into the well-defined Systems Identification (SID) domain where the whole calibration problem is considered in terms of the systems identification design steps. The main contributions presented in this study are that the traditional calibration strategy is reviewed by casting the calibration problem into the Systems Identification domain; that a unified FOG error model is developed that combines a number of seemingly contradictory error models available in the technical literature; that computational intelligence techniques are used to perform gyro calibration; that a novel, non-linear gyro calibration strategy is developed; and that the sensors are calibrated under the simultaneous dynamic excitation of the full range of multi-dimensional environmental conditions. In the process of the development of this new calibration strategy the need for a problemspecific Criterion of Fit was observed. Such a Criterion of Fit was therefore developed and it acted as the core criterium whereby the accuracy of the new calibration strategy was assessed. One of the most important results obtained from the research presented in this thesis is that the new strategy significantly outperforms the traditional strategies and that, with the availability of high-performance embedded computational platforms, it has potential to be used within an operational environment as the gyro compensation strategy of choice.
13

Étude et calibration d’un hydrophone embarqué sur un flotteur dérivant - application à la sismologie / Study and calibration of a hydrophone mounted on a drifting float - seismological application

Joubert, Cécile 18 May 2015 (has links)
Dans ce travail, nous proposons une étude générale des hydrophones, leur fonctionnement suivant le principe de la piézoélectricité, les éléments les constituant ainsi que les brevets et les hydrophones existants. Nous modélisons les courbes de sensibilité à la réception et à l'émission avec le logiciel COMSOL que nous comparons avec des hydrophones en notre possession. Avec ces modèles, nous proposons le design d'un hydrophone potentiel, large bande, viable à de grandes immersions (>6000 m). Nous testons deux nouvelles méthodes de calibration d'hydrophone à basses fréquences (< 2 Hz) que nous appliquons aux hydrophones des flotteurs MERMAID. Dans la méthode «dynamique», la réponse de l'hydrophone est étudiée suite à l'application d'une brève surpression (1000 Pa avec tτ < 1 s), réalisée par le déplacement vertical de l'hydrophone dans l'eau. La méthode «statique» permet d'étudier la réponse du système d'acquisition complet. L'hydrophone est placé dans un caisson étanche dans lequel une surpression est générée par l'ajout d'une colonne d'eau placée au-dessus. Nous déterminons les pôles et zéros de la chaîne d'acquisition des flotteurs. La correction des sismogrammes enregistrés par trois flotteurs MERMAID déployés en mer Méditerranée, nous permet d'estimer la pression générée par le séisme de Barcelonnette à environ 400 Pa (7 avril 2014, Mw = 4,8). Nous validons les données acquises par les MERMAID dans une étude sismologique. Nous étudions les données de six mois d'enregistrements par les trois flotteurs déployés en mer Ligure, développons un protocole de pré-traitement des données que nous validons avec une étude tomographique. / In this work, we propose a general study of hydrophones focusing on their operation, based on the piezoelectric principle, the different elements that compose them and the available hydrophones and patents. We model reception and emission sensibility curves with COMSOL software and compare with hydrophones at our disposal, allowing us to qualitatively estimate the sensitivity. We propose a design for a potential broadband hydrophone, viable at large depths (> 6000 m). We test new methods of hydrophone calibration at low frequencies (< 2 Hz) and apply them to the MERMAID floats hydrophone. In the «dynamic» method, the hydrophone response is studied with a brief pressure variation (1000 Pa with tτ < 1 s), performed by a winch, which vertically moves the hydrophone into water. The «static» method allows us to study the full system response. The hydrophone is placed in a calibration chamber in which a pressure variation is performed with an additional water column. We have determined poles and zeros applicable to the MERMAID. The correction of seismograms recorded by three MERMAID floats, deployed in the Mediterranean Sea, allows us to estimate the pressure variation produced by the Barcelonnette earthquake which is around 400 Pa (April 7, 2014, , Mw = 4,8). We validate the data acquired by the MERMAID in a seismological study. We study data of six months of acquisition of the three floats deployed in the Ligurian Basin, develop a preprocessing method of these data and validate with a tomographic study.
14

Improving the robustness of multivariate calibration models for the determination of glucose by near-infrared spectroscopy

Kramer, Kirsten Elizabeth 01 January 2005 (has links)
Near-infrared spectroscopy has proven to be one of the most promising techniques for the development of a noninvasive blood glucose monitoring system for diabetic patients. In this work, Fourier transform infrared (FT-IR) transmission measurements of the combination band region (4000 - 5000 cm-1) were analyzed for samples containing glucose (analyte) in a matrix of bovine serum albumin and triacetin (models for proteins and fats), all spanning physiological levels relevant for a diabetic patient. The first part of the study investigated the required spectral point-spacing for accurate detection of glucose. This was studied by systematically truncating interferograms before Fourier transforming them to single-beam spectra. A set of training data (70 samples) was collected for multivariate calibration using partial least-squares (PLS) and an external prediction set was used to verify the success of modeling glucose quantitatively. It was found that a relatively large point-spacing (16 cm-1) was successful for prediction of glucose, meaning that a shorter interferogram could be collected. The second part of the study involved collecting interferograms such that the spectral resolution was 16 cm-1, and investigating methods to extend the usefulness of calibration models for long-term data collection. Near-infrared spectroscopy often suffers from weak signals that are overwhelmed by significant instrumental drift, meaning that calibration models tend to be unsuccessful for data collected several days or months outside the calibration. For updating the calibration models, a set of 50 backgrounds containing only matrix constituents without analyte was collected on each analysis day, and used to update the original calibration model so that instrumental drift features were incorporated into the model. Background updating was found to be successful in single-beam format, producing a background-augmented (BA) PLS model that significantly improved single-beam data analysis. The standard error of prediction using the original model (PLS) and the updated model (BA-PLS) were 13.4 and 0.79 mM glucose, respectively, for a prediction set taken 176 days outside of the calibration. The matrix data also allowed for studies in background selection methods for absorbance computations as well as adaptive digital filtering that was guided by the background data.
15

The Virginia Tech Calibration System

Fernandez, Javier Oscar 10 June 2011 (has links)
Phasor measurement unit (PMU) applications on power grid monitoring systems have been implemented since the early ninety's. Large monitoring system network performance relies on the consistent measurements of PMUs across the system. This has become a major challenge for designers since large networks use PMUs from various manufacturers who likely implement different synchrophasor technologies to perform the phasor estimations. The current synchrophasor standard, the IEEE C37.118-2005 Synchrophasor Standard, covers adequately the steady-state characterization of PMUs but does not specify transient condition requirements. The North American Synchrophasor Initiative (NASPI) has developed a guide outlining the several tests required for dynamic characterization of PMUs. The National Institute of Standards and Technology (NIST) developed two PMU testing stands for steady-state conformance with the current standard and for dynamic performance testing. Since May 2010, Virginia Tech has been working closely with the NIST in developing a PMU testing system similar to the NIST designs for commercial testing of PMUs and research purposes, the Virginia Tech Calibration System. This thesis focuses on assessing the system accuracy differences between the designs, and the software interface modifications to adapt the new hardware. / Master of Science
16

An Auto-Calibration System for a Longitudinal Magnetic Recorder

Andersen, R., Wendel, W. 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / Multiple channel magnetic tape recording is often used for signal analysis of intelligence and telemetry data. To insure accuracy of the reproduced data, these systems require frequent calibration and alignment. As the number of tracks on these systems has increased, this task has become more time-consuming. Even with a well-trained technician, this task can take several hours at a minimum. To alleviate this problem, we developed a system for performing this calibration automatically. The implementation utilizes a Fast-Fourier-Transform technique to analyze the output of a pre-recorded signal on tape. The desired response, most frequently defined by IRIG Standards, is stored in a look-up table in the machine. The actual response is compared to that desired, and, under micro-processor control, adjustment made in the signal channel until an acceptable response is achieved. A unique photo-resistor technique is used in the signal path to control such parameters as gain and phase. A description of the hardware system will be given, as well as a description of the algorithms utilized for implementation.
17

AN AUTO-CALIBRATION SYSTEM FOR A LONGITUDINAL MAGNETIC RECORDER

ANDERSEN, R., WENDEL, W. 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, California / Multiple channel magnetic tape recording is often used for signal analysis of intelligence and telemetry data. To insure accuracy of the reproduced data, these systems require frequent calibration and alignment. As the number of tracks on these systems has increased, this task has become more time-consuming. Even with a well-trained technician, this task can take several hours at a minimum. To alleviate this problem, we developed a system for performing this calibration automatically. The implementation utilizes a Fast-Fourier-Transform technique to analyze the output of a pre-recorded signal on tape. The desired response, most frequently defined by IRIG Standards, is stored in a look-up table in the machine. The actual response is compared to that desired, and, under micro-processor control, adjustment made in the signal channel until an acceptable response is achieved. A unique photo-resistor technique is used in the signal path to control such parameters as gain and phase. A description of the hardware system will be given, as well as a description of the algorithms utilized for implementation.
18

Optimized Automatic Calibration Tool for Flight Test Analogue Parameters

Torralbo, Pilar Vicaria 10 1900 (has links)
ITC/USA 2015 Conference Proceedings / The Fifty-First Annual International Telemetering Conference and Technical Exhibition / October 26-29, 2015 / Bally's Hotel & Convention Center, Las Vegas, NV / The calibration processes consume a big quantity of resources: equipment and people, time and cost. As the number of calibration points increase the resources increase in the same extent. This automatic tool, aimed to reduce these resources, has been designed for commanding, managing and analyzing in real time a large number of acquired data points coming from the specimen under calibration and the standards used in the calibration process, applying at the same time the metrological algorithms which validate the calibration point. Its greatest achievement is the implementation of the rules for accepting or discarding the data point and the level of automation of the process. In the last flight test campaign its usage has been crucial for providing on time the data with the high accuracy required. It was achieved the commissioning of almost 200 temperature parameters in a short period of time taking advantage of equipment which nominal accuracy was not high enough for their direct application.
19

A study of capacitor array calibration for a successive approximation analog-to-digital converter

Ma, Ji, active 2013 07 October 2014 (has links)
Analog-to-digital converters (ADCs) are driven by rapid development of mobile communication systems to have higher speed, higher resolution and lower power consumption. Among multiple ADC architectures, successive approximation (SAR) ADCs attract great attention in mixed-signal design community recently. It is due to the fact that they do not contain amplification components and the digital logics are scaling friendly. Therefore, it is easier to design a SAR ADC with smaller component size in advanced technology than other ADC architectures, which decreases the power consumption and increases the speed of the circuit. However, capacitor mismatch limits the minimum size of unit capacitors which could be used for a SAR ADC with more than 10 bit resolution. Large capacitor both limits conversion speed and increases switching power. In this design project, a novel switching scheme and a novel calibration method are adopted to overcome the capacitor mismatch constraint. The switching scheme uses monotonic switching in a SAR ADC to gain one extra bit, and switches a dummy capacitor between the common mode voltage level (Vcm) and the ground (gnd) to obtain another extra bit. To keep the resolution constant, the capacitor number is reduced by two. The calibration method extracts missing code width to estimate the actual value of capacitors. The missing code extraction is accomplished by detecting metastable state of a comparator, forcing the current bit value and using less significant bits to measure the actual capacitor value. Dither method is adopted to improve calibration accuracy. Behavior model simulation is provided to verify the effectiveness of the calibration method. A circuit design of a 12 bit ADC and the simulation for schematic design is presented in this report. / text
20

Study of the calibration and accuracy specification of coordinate measuring machines

Voutsadopoulos, C. M. January 1980 (has links)
No description available.

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