1,720,961 research outputs found
Dynamic modeling and simulation of a biped robot
No full textDie vorliegende Arbeit beschäftigt sich mit der Stabilität von zweibeinigen (humanoiden) Robotern während des gehens. Dieses Forschungsgebiet zeichnet sich dadurch aus, dass es eine Unzahl von Publikationen gibt, von denen die Mehrzahl auf der klassischen Zero-Moment-Point (ZMP) Methode beruhen. Zunächst wird ein kurzer Überblick über humanoide Roboter gegeben und auf Modelle für das dynamische Verhalten eingegangen. Hauptziel der Arbeit is es, die Stabilität eines, am IHRT entwickelten, zweibeinigen Roboters zu untersuchen. Derzeit existiert der Unterteil - bestehend aus Füßen, Beinen, Hüften und dem halben Oberkörper. Diese Struktur hat derzeit elf Freiheitsgrade. Im Endstadium soll der Roboter einundreißig Freiheitsgrade aufweisen. Zunächst wurde das bestehende Unterteil mittels Matlab/Simmechanics simuliert, wobei das nach Newton-Euler abgeleitete Modell Verwendung fand. Aus den sich ergebenden Schritt-Trajektorien folgte, dass eine Stabilisierung nur für eine Schritthöhe von maximal 5 cm unter optimalen Bedingungen möglich war was für den gehvorgang nahe an der Stabilitätsgrenze liegt.Daher wird die gesamte Struktur mit einundreißig Freiheitsgraden simuliert. Hier zeigte sich, dass durch Synchronisation der Arm und Beinbewegungen, ähnlich wie beim menschlichen Gang, eine bessere Stabilität erreicht werden kann. Darüber hinaus werden konstruktive Vorschläge zu Verbesserung der Massenverteilung (tieferer Schwerpunkt) gemacht.Simulationen des gesamtstruktur einschließlich der konstruktivän Änderungen zeigten, dass mit diesen Maßnahmen eine wesentliche Verbesserung der Stabilität erreicht werden kann. Es wurden optimale Schritt-Trajektorien mit einer Schritthöhe von 15 cm und einer Schrittweite von 60 cm erreicht was dem menschlichen fang bereits sehr nahe konnte.This work deals with the stability analysis of two legged (humanoid) robots during walking. This research area is characterized by the fact that there are a lots of publications, most of which are based on the classic ZMP method. First, a brief overview is provided on humanoid robots, and also models for the dynamic behavior are discussed. Main aim of this work is to investigate the stability of a biped robot developed from IHRT. There is currently the low base of robot - consisting of feet, legs, hips and upper part of robots body. This structure currently has eleven degrees of freedom. In the final stage, the robot should have 31 DoF-s. First, the existing low base of robot was simulated using Matlab / SimMechanics, where the derived by Newton-Euler model was used. From the resulting step trajectories followed that stabilization was only possible for a step height of more than 5 cm in optimal conditions, what for the going-process is close to the stability limit. Therefore the entire structure with 31 DoF-s will be simulated. This showed that by synchronizing the arm and leg movements, similar to the human gait, greater stability can be reached. In addition, suggestions to improve the weight-distribution has been made (lower CoG). Simulations of the overall structure, including the constructive changes showed that with these measures a significant improvement of the stability can be achieved. There are found optimal step-trajectories with a step-height of 15 cm and step-width of 60 cm that are already very close to the human fang
Dynamic Modeling and Analysis of Propulsion effect of 3 DoF robot
Full text linkDynamical Modeling of robots is commonly first important step of Modeling, Analysis and Control of robotic systems. This paper is focused on using Denavit-Hartenberg (DH) convention for kinematics and Newton- Euler Formulations for dynamic modeling of 3 DoF - Degree of Freedom of 3D robot. The process of deriving of dynamical model is done using Software Maple. Simulations are done using Matlab/Simulink for analysis of propulsion effect under Earth gravity when First Link rotates with 1000 rpm, second Link can move free in vertical direction and Third Link can rotates free around their rotations axle. Simulations results shows very good propulsion of proposed 3 DoF robot. Results are verified-compared with constructed model of 3 DoF robot using Working Model 3D Software
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe 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
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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