1,720,978 research outputs found
Multirotor fault tolerance based on center-of-mass shifting in case of rotor failure
No full textThis work carries out an analysis on fault tol-erance in multirotor vehicles, particularly for an hexarotorone, where such feature is achieved by shifting the center ofmass in case of a motor failure. It will be shown that, foran hexarotor vehicle, for each of the possible motor failures,there exists an optimal fixed position for the center of mass, inorder to keep independent control of four degrees of freedom,and to obtain the best maneuverability. The performance ofthis solution will be compared with a previous design based onmotor reconfiguration in case of a motor failure.Fil: Pose Claudio. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; ArgentinaFil: Giribet, Juan Ignacio. Universidad de San Andrés; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaInternational Conference on Unmanned SystemsAtenasGreciaIEEE RA
Adaptive Center-of-Mass Relocation for Aerial Manipulator Fault Tolerance
No full textThis work proposes a fault tolerant aerial manipulator based on a standard hexarotor vehicle, which is able to maintain independent control of torque and vertical thrust in case of motor failure by adequately changing the manipulator configuration and therefore modifying the position of the system's center of mass. By analyzing the disturbance torque that the manipulator exerts on the vehicle, conditions to achieve stable flight and operation limits are established. To provide an experimental proof of concept, several flights are performed, both in indoor and outdoor environments, for different size and weight of manipulators.Fil: Pose, Claudio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires; ArgentinaFil: Giribet, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de San Andrés; ArgentinaFil: Mas, Ignacio Agustin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de San Andrés; Argentin
Diseño de una computadora de navegación, guiado y control. Aplicación a un Vehículo Aéreo no tripulado
Get PDFEl propósito de este trabajo es presentar un prototipo de computadora de navegación, guiado y control que ha sido desarrollado en el GPSIC. El aporte principal del trabajo es el desarrollo de la arquitectura y firmware del sistema. Como ejemplo de aplicación se muestran resultados en donde esta computadora se utiliza en un vehículo aéreo no tripulado del tipo multirotor.Fil: Pose, Claudio Daniel. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Roasio, Federico. Universidad de Buenos Aires. Facultad de Ingeniería; ArgentinaFil: Giribet, Juan Ignacio. Universidad de Buenos Aires. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaVIII Jornadas Argentinas de RobóticaArgentinaUniversidad Tecnológica Nacional. Facultad Regional Buenos Aire
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Fault tolerance analysis for a class of reconfigurable aerial hexarotor vehicles
No full textSeveral works have addressed the issue of fault tolerance in multirotors in case of a rotor total failure, particularly their ability to keep full independent control of attitude and altitude. It has been proven that to achieve this, a minimum of six rotors is needed. In this article, the performance of several standard and nonstandard hexarotor structures is analyzed, both for a nominal case (without failure) and in the case where one of the actuators is under failure (incapability to exert thrust). The performance is shown in terms of maximum rotational torque and vertical force that the vehicle can exert. The main contribution of this article is the proposal and analysis of converting these vehicles into reconfigurable ones through the addition of a minimum number of servomotors, to deal with failures and to greatly improve the maneuverability under these conditions, in order to identify the reconfigurable structure with the best performance. An experimental demonstration in an outdoor environment is shown for the proposed reconfigurable structure with best performance in case of a full rotor failure.Fil: Pose, Claudio Daniel. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; ArgentinaFil: Giribet, Juan Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Instituto Argentino de Matemática Alberto Calderón; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; ArgentinaFil: Ignacio Mas. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ingeniería. Departamento de Electronica; Argentina. Instituto Tecnológico de Buenos Aires; ArgentinaInternational Conference on Advanced Intelligent MechatronicsBostonEstados UnidosAmerican Society Of Mechanical Engineer
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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