1,720,975 research outputs found
Strategie di Controllo Avanzate per la Robotica Chirurgica
No full textLa robotica chirurgica può essere considerata ormai una realtà consolidata in campo medico. L'esempio più eclatante è sicuramente il robot chirurgico da Vinci®, rilasciato da Intuitive Surgical quasi 20 anni fa. Si stima che, solamente nel 2012, con il da Vinci® siano stati effettuati più di 200.000 interventi chirurgici, la maggior parte dei quali per isterectomie e asportazioni di prostata. Al giorno d'oggi, la maggior parte delle operazioni chirurgiche robotizzate vengono eseguite utilizzando tecniche di teleoperazione, nelle quali i movimenti del robot vengono direttamente controllati dal chirurgo, il quale siede ed opera da una console remota. In questo tipo di operazione il robot non possiede alcuna capacità di prendere decisioni o eseguire compiti in modo autonomo. Quest'ultimo è proprio uno dei principali temi sul quale si concentra oggi la ricerca in robotica chirurgica. L'autonomia, infatti, può offrire importanti vantaggi, che includono una maggiore efficienza e ripetibilità grazie al controllo sub-millimetrico del robot, una migliore qualità di esecuzione grazie al monitoraggio di segnali biometrici in tempo reale e alla guida assistita da computer, e minori costi. Un altro fattore che ha spinto in questa direzione sono stati sicuramente gli importanti sviluppi in tema di intelligenza artificiale, che hanno caratterizzato gli ultimi decenni. Tuttavia, è necessario tenere in considerazione che rendere autonomo un sistema robotico-chirurgico apre nuove importanti sfide in termini di controllo. Il sistema deve essere infatti in grado di, ad esempio, percepire l'ambiente circostante per cooperare con altri sistemi evitando collisioni, comprendere le dinamiche dell'ambiente per interagire con esso e compensare i disturbi esterni, e rispettare tutti i vincoli necessari ad eseguire correttamente la procedura chirurgica. Un altro problema importante quando si rende autonomo un sistema di questo tipo è la raccolta dei dati necessari per l'addestramento del sistema stesso, che spesso sono pochi e difficili da acquisire. Il lavoro di questa tesi inizia ad affrontare alcuni di questi difficili problemi ed emersi nello sviluppo del progetto Europeo Smart Autonomous Robotic Assistant Surgeon. Il primo passo è stato quello di convertire una procedura laparoscopica standard in una completamente robotizzata, realizzando un'architettura di teleoperazione per applicazioni a più bracci robotici, in grado di fornire feedback visivo e feedback di forza stabile. Questa architettura è stata sviluppata specificamente per la raccolta dei dati ed è stata utilizzata per l'addestramento della parte relativa all'intelligenza artificiale. Inoltre, i risultati ottenuti sono stati estesi realizzando un'architettura di teleoperazione trilaterale volta al training. Successivamente, il lavoro si è concentrato sullo sviluppo del sistema di pianificazione e coordinamento per il controllo di più strumenti robotizzati. Il sistema proposto mira a gestire l'incertezza fornita dal modulo cognitivo e a generare un movimento autonomo sicuro e privo di collisioni. Grazie all'esperienza acquisita durante lo sviluppo delle strategie precedenti, è stata poi sviluppata un'architettura di assistenza robotica per la procedura di accesso renale durante la nefrolitotomia percutanea. L'ultimo problema affrontato in questo lavoro di tesi è stato il controllo del centro di istantanea rotazione per sistemi robotici senza centro di istantanea rotazione meccanico. L'architettura proposta considera gli effetti che questo vincolo provoca sulla dinamica del sistema e propone un controllore che mira a gestire il vincolo massimizzando flessibilità e prestazioni. Questo controllore è stato poi proposto anche all'interno di un'architettura di teleoperazione. Tutti i sistemi proposti sono stati validati sperimentalmente su set-up fisici, con l'obiettivo di verificare e confermare l'applicabilità e l'efficacia di ciascuno di essi.Surgical robotics can be considered an established reality in the medical field. The most striking example is the release of the da Vinci® surgical system by Intuitive Surgical almost 20 years ago. It is estimated that more than 200 000 surgeries were carried out with the da Vinci® in 2012 only, most of which were for hysterectomies and prostate removals. Most robotized surgical operations are performed using teleoperation techniques, where the surgeon sits on a remote console and has complete control of the movements of the robot, without the possibility for the robot to make decisions or perform tasks autonomously. The latter is one of the main topics on which researches in surgical robotics are focused nowadays. Indeed, autonomy can give important advantages, which include increased efficiency and repeatability due to precise robot control, improved execution quality thanks to real-time biosignal feedback and computer-aided guidance, and fewer costs. The important developments that have characterized the last decades in terms of artificial intelligence have pushed even further in this direction. However, it is necessary to take into account that making a robotic surgical system autonomous opens up new important challenges in terms of control. The system must be able, for example, to perceive the surrounding environment to cooperate with other systems while avoiding collisions, understand the environment dynamics to interact with it and to compensate external disturbances, and comply with all the constraints necessary to perform the surgical procedure correctly. Another important problem when making a system autonomous is the collection of data necessary for the training of the system, which are often few and difficult to acquire. The work of this thesis starts to address some of these challenging problems arising during the development of the European-funded project Smart Autonomous Robotic Assistant Surgeon. First, a standard laparoscopic procedure was fully robotized with a teleoperation architecture providing stable force feedback and visual feedback capabilities have been proposed for multi arms systems. This architecture was specifically developed for data collection and was used for artificial intelligence training. Moreover, the results obtained have been extended for building a trilateral teleoperation architecture for training purposes. In the following, the work concentrated on developing the planning and coordination system for the control of multiple robotic instruments. The proposed system aims to deal with the uncertainty provided by the cognitive module and to generate a safe collision-free autonomous motion. Thanks to the experience acquired during the development of the previous strategies, a robotic assistance architecture for the renal access procedure during Percutaneous nephrolithotomy has been developed. The last problem addressed in the thesis is the control of the remote center of motion for robotic systems without mechanical remote center of motion. The proposed architecture considers the effects this constraint causes on the dynamics of the system and proposes a controller that aims to deal with the constraint maximizing flexibility and performance. This controller is also proposed within a teleoperation setup. All the proposed systems have been experimentally validated on physical setups, with the aim of verifying and confirming the applicability and the effectiveness of each of them
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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