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Evaluation of vision-based robot control configurations for reconfigurable assembly
Get PDFThesis (MEng)--Stellenbosch University, 2016.ENGLISH ABSTRACT: This thesis considers vision based robot control for a reconfigurable manufacturing cell. Reconfigurable manufacturing systems are aimed at rapidly adapting to fluctuations in market demand, shorter product life cycles and product customization. Computer vision is a promising component of such manufacturing systems, in particular aiding the flexibility to handle a range of products with reduced set-up time and fewer fixtures.
The objective of the research presented here was to develop a simulation-based approach to compare eye-in-hand and fixed camera vision-based control within a reconfigurable assembly cell. These configurations have dissimilar system costs and system performance characteristics. The research used a KUKA six degree of freedom articulated arm robot, a DVT Legend 540 camera and a Cognex ism-1100 camera, as well as the software supplied with the cameras. The simulation was aimed at predicting the throughput rate of multiple eye-in-hand and fixed camera configurations, where configurations include varying the numbers of reconfigurable singulation units, positions of machines, parts being singulated, etc. The throughput rates for different configurations can then be compared to their costs and ease of reconfiguration.
The simulation uses a holonic control system that was designed based on the ADACOR architecture. The thesis describes in detail the holons used, including their hardware, data structures and responsibilities. A multi-agent system was implemented for high-level control and some of the agents communicated with their respective lower-level controllers during validation testing. In the simulation, software (including KUKA Simpro and some custom software) replaced the hardware and low-level controllers. Tests on a number of physical laboratory configurations were used to validate the simulation.
The simulation's application is demonstrated in a number of experiments in which cell configurations and machine performance were varied. For example, for a particular situation simulated, these experiments showed that the eye-in-hand configuration has a competitive cost to performance ratio when tasks have a significant waiting period (pallet exchange time, tasks deployed sparsely, etc.). In most experiments, however the fixed camera configuration performs better. The simulation allowed “hardware in the loop” testing, which also makes it a useful tool for development of the cell.AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek visie-gebaseer robotbeheer vir 'n herkonfigureerbare vervaardigingsel. Herkonfigureerbare stelsels is daarop gemik om vinnig aan te pas by skommelinge in die markaanvraag, korter produklewensiklusse en produk-aanpassings. Rekenaarvisie is 'n belowende onderdeel vir sulke stelsels, in besonder vir die buigsaamheid hantering van 'n reeks produkte met verminderde opsteltyd en verminderde gebruik van setmate.
Die doel van navorsing wat hier aangebied word, was om 'n simulasie-gebaseerde benadering te ontwikkel vir die keuse tussen "eye-in-hand-" en vaste-kamera-beheer in 'n herkonfigureerbare samestelling-sel. Hierdie konfigurasies het verskillende eienskappe ten opsigte van stelselkoste en -werkverrigting. Die navorsing het 'n Kuka ses vryheidsgraad geartikuleerde-arm-robot, 'n DVT Legend 540 kamera and 'n Cognex ism-1100 kamera, asook die programmatuur wat met die kameras voorsien word, gebruik. Die simulasie is daarop gemik om die deursetkoers van verskillende "eye-in-hand-" en vaste-kamera-konfigurasies te voorspel, waar konfigurasies verskillende aantal herkonfigureerbare singulasie-eenhede, posisies van masjiene, onderdele wat gesinguleer word, ens. insluit. Die deursetkoerse van verskillende konfigurasies kan dan met hul koste vergelyk word.
Die simulasie gebruik 'n holoniese beheerstelsel, gebaseer op die ADACOR argitektuur. Die tesis beskryf in detail die holons wat gebruik is, insluitend hul hardeware, datastrukture en verantwoordelikhede. 'n Multi-agent-stelsel is geïmplementeer vir die hoë-vlak-beheer en sommige agente het met hul onderskeie laer-vlak-beheerders tydens validasie-toetse gekommunikeer. In die simulasie is die hardeware en lae-vlakbeheerders vervang met programmatuur (insluitend Kuka Sim Pro en sommige doelgemaakte programmatuur). Toetse op 'n aantal fisiese laboratorium-konfigurasies is gebruik om die simulasie te valideer.
Die simulasie se toepassing is gedemonstreer in 'n aantal eksperimente waarin selkonfigurasies en masjienprestasie gewissel is. Byvoorbeeld, vir 'n spesifieke konfigurasie wat gesimuleer is, het die eksperimente getoon dat die "eye-in-hand"-konfigurasie 'n laer koste-tot-prestasie-verhouding het wanneer take 'n beduidende wagtydperk (ruiltyd vir pallette, take yl ontplooi, ens.) het. Die simulasie het "hardeware in die lus" toetsing moontlik gemaak, wat dit ook 'n nuttige hulpmiddel maak tydens die ontwikkeling van die sel
Deep active-learning based model-synchronization of digital manufacturing stations using human-in-the-loop simulation
No full textThe effective and accurate modeling of human performance is one of the key technologies in virtual/smart manufacturing systems. However, a significant challenge lies in acquiring sufficient data for such modeling. Virtual Reality (VR) emerges as a promising solution, making human manufacturing experiments more practical and accessible. In this paper, we present a novel framework that efficiently models human assembly duration by leveraging VR to prototype data-acquisition systems for assembly tasks. Central to the framework is an active learning model, which intelligently selects experimental conditions to yield the most informative results, effectively reducing the number of experiments required. As a result, the system demands fewer experimental trials and operates on an automated basis. In VR experiments involving throughput rate, the active model significantly reduces the data requirement, thereby expediting the experiment and modeling process. While this framework demonstrates remarkable efficiency, it does exhibit sensitivity to non-constant noise and may necessitate prior data from similar assembly tasks to identify high-noise. Notably, this proposed method extends beyond manufacturing, allowing the quick generation of human performance models in virtual systems and enhancing experiment scalability across various fields. With its potential to revolutionize human performance modeling, our framework represents a promising avenue for advancing virtual/smart manufacturing systems and other related applications
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
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
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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