Alternative method for the metrological characterization of spur gears in the sub-millimeter range using optical equipment

The aim of this work is to develop a software that allows the inspection of spur gear manufactured in the sub-millimeter range. The measurements are made using a digital optical machine and using an analysis proprietary software implemented in Matlab®, which is able to handle images, captured using the digital optical machine. The software allows to evaluate the profile and pitch deviations as establish in the ISO/TR 10064-1:1992 standar

A proposal for the metrological characterization of circular features with digital optical machines

This paper aims to analyze the different adjustment methods commonly used to characterize indirect metrology circular features: least square circle, minimum zone circle, maximum inscribed circle and minimum circumscribed circle. The analysis was performed from images obtained by digital optical machines. The calculation algorithms, self-developed, have been implemented in Matlab® and take into consideration as study variables: the amplitude of angular sector of the circular feature, its nominal radio and the magnification used by the optical machine. Under different conditions, it was determined the radius and circularity error of different circular standards. The comparison of the results, obtained by the different methods of adjustments used, with certified values for the standards, has allowed us to determine the accuracy of each method and its scope

Uncertainty in ellipse fitting using a flatbed scanner: development and experimental verification

In the field of dimensional metrology, the use of optical measuring machines requires the handling of a large number of measurement points, or scanning points, taken from the image of the measurand. The presence of correlation between these measurement points has a significant influence on the uncertainty of the result. The aim of this work is the development of an estimation procedure for the uncertainty of measurement in a geometrically elliptical shape, taking into account the correlation between the scanning points. These points are obtained from an image produced using a commercial flat bed scanner. The characteristic parameters of the ellipse (coordinates of the center, semi-axes and the angle of the semi-major axis with regard to the horizontal) are determined using a least squares fit and orthogonal distance regression. The uncertainty is estimated using the information from the auto-correlation function of the residuals and is propagated through the fitting algorithm according to the rules described in Evaluation of Measurement Data—Supplement 2 to the ‘Guide to the Expression of Uncertainty in Measurement’—Extension to any number of output quantities. By introducing the concept of cut-off length, it can be observed how it is possible to take into account the presence of the correlation in the estimation of uncertainty in a very simple way while avoiding underestimation

Recomendaciones para una correcta información sanitaria que evite confusión e inexactitudes en el conocimiento de la mortalidad provocada por la infección de COVID-19 en España

Introduction: Accurate communication of the fatality rate associated to COVID-19 pandemic should be a priority in the fight against it; having a reliable knowledge of this information concerns social rights, and it is a key aspect of public awareness. Aims: Mortality data from Spain and the European neighborhood have been assessed, with regards to the importance of providing precise information about the mortality of COVID-19. Methodology: Excess mortality and COVID-19 official data deaths have been compared from different institutions, paying special attention to the Spanish case. Likewise, the national situation has been analyzed with respect to the European neighboring countries. Results: Relevant disagreement and absence of uniform criteria, in the communication of the information regarding COVID-19 deaths are found; this hinders the proper communication to population and threatens decision-taking. Conclusions: Communication of pandemicrelated deaths from the official institutions should follow the criteria from WHO, and official data should include clinical suspicious deaths in order to reduce uncertainties and misleads in subsequent diffusion of these data by the media.Introducción: La comunicación correcta del número de fallecimientos asociados a la pandemia COVID-19 debería ser una prioridad en la lucha contra la pandemia; el conocimiento certero de esa información es un derecho de la sociedad y constituye un pilar fundamental en la concienciación general. Objetivos: Considerando la importancia de informar de forma concreta sobre la mortalidad por COVID-19, se han comparado los datos de mortalidad evaluando el ámbito nacional y comparándolo con la escala europea. Metodología: Se comparan los datos de exceso de mortalidad y decesos por COVID-19, conforme a la información disponible en diversas fuentes institucionales, con atención particular al caso de España y se analiza la situación nacional dentro del conjunto europeo. Resultados: Se detectan importantes discrepancias y ausencia de criterios uniformes, lo que dificulta dar una información clara y concisa a la población y la toma de decisiones para su contención. Conclusión: La comunicación realizada desde los organismos oficiales encargados del seguimiento y comunicación de los efectos de la pandemia deberían seguir los criterios de la OMS y actualizarse incluyendo los fallecidos por causa de la COVID-19 confirmados o probables, para evitar equívocos en la posterior difusión de las cifras de mortalidad por los medios de comunicación

Modelo para la medición con máquinas de visión e iluminación episcópica mediante la aplicación de técnicas de resolución subpíxel y aproximación bayesiana

En esta tesis se desarrolla un modelo físico-matemático, original, que permite simular el comportamiento de las máquinas de visión, en particular las máquinas ópticas digitales, cuando reciben información a través de la luz reflejada por los mensurandos. El modelo desarrollado se lia aplicado para la determinación de los parámetros que intervienen en el proceso de caracterización de formas geométricas básicas, tales como líneas, círculos y elipses. También se analizan las fuentes de error que intervienen a lo largo de la cadena metrológica y se proponen modelos de estimación de las incertidumbres de medida a través un nuevo enfoque basado en estadística bayesiana y resolución subpíxel. La validez del modelo se ha comprobado por comparación de los resultados teóricos, obtenidos a partir de modelos virtuales y simulaciones informáticas, y los reales, obtenidos mediante la realización de medidas de diferentes mensurandos del ámbito electromecánico y de dimensiones submilimétricas. Utilizando el modelo propuesto, es posible caracterizar adecuadamente mensurandos a partir del filtrado, segmentación y tratamiento matemático de las imágenes. El estudio experimental y validación definitiva de los resultados se ha realizado en el Laboratorio de Metrología Dimensional de la Escuela Técnica Superior de Ingeniería y Diseño Industrial de la Universidad Politécnica de Madrid. Los modelos desarrollados se han implementado sobre imágenes obtenidas con la máquina de visión marca TESA, modelo VISIO 300. Abstract In this PhD Thesis an original mathematic-physic model has been developed. It allows simulating the behaviour of the vision measuring machines, in particular the optical digital machines, where they receive information through the light reflected by the measurands. The developed model has been applied to determine the parameters involved in the process of characterization of basic geometrical features such as lines, circles and ellipses. The error sources involved along the metrological chain also are analyzed and new models for estimating measurement uncertainties through a new approach based on Bayesian statistics and subpixel resolution are proposed. The validity of the model has been verified by comparing the theoretical results obtained from virtual models and computer simulations, with actual ones, obtained by measuring of various measurands belonging to the electromechanical field and of submillimeter dimensions. Using the proposed model, it is possible to properly characterize measurands from filtering, segmentation and mathematical processing of images. The experimental study and final validation of the results has been carried out in the "Laboratorio de Metrología Dimensional" (Dimensional Metrology Laboratory) at the Escuela Técnica Superior de Ingeniería y Diseño Industrial (ETSIDI) (School of Engineering and Industrial Design) at Universidad Politécnica de Madrid (UPM). The developed models have been implemented on images obtained with the vision measuring machine of the brand TESA, model VISIO 300

Wohnungsgemeinnuetzigkeit morgen: Dokumentation d. Symposiums zur Novellierung d. WGG vom 19. - 20. Maerz 1987 in Bonn

Includes 6 articlesAvailable from Bibliothek des Instituts fuer Weltwirtschaft, ZBW, Duesternbrook Weg 120, D-24105 Kiel C 151543 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Bayesian model for subpixel uncertainty determination in optical measurements

Uncertainty determination can be obtained by two procedures: GUM and the Monte Carlo Method. This work presents a model that helps to evaluate the uncertainty in measurements collected by optical measuring machines when using the Monte Carlo method. Initially, the model converts intensity, using Bayesian probability, from the pixel image derived from camera into a polygonal area with three to five vertexes. The outer vertexes are fitted using least squares procedures to obtain a measurand shape approximation in a subpixel range. Algorithms have been programmed and verified into Matlab using synthetic images with different triangles. Through a detailed analysis, the usefulness of a new tool, the parameter, will be demonstrated as an alternative method for estimating uncertainty of measurements of pixel images