1,721,021 research outputs found
Optimization-based methods for stable and robust motion generation and control in mobile robots
No full textWhile Robotics is seeing an ever-increasing adoption in both industrial and service applications, truly autonomous robots are still far from being widespread.
One of the limiting factors is in the availability of adaptable, performant and robust control methods to generate complex motions for such systems. At the moment, Model Predictive Control (MPC) stands out among the most promising techniques to fill this gap. In fact, with its ability to minimize a cost function while respecting a set of constraints that represent physical and operational limitations of a system, MPC is capable of outperforming classic approaches, and its predictive nature makes it adaptable to a large range of tasks.
This thesis presents a series of motion generation methods based on Model Predictive Control with the aim of improving over the current methodologies in two aspects: the first being the treatment of systems that exhibit a non-minimum phase behavior and thus pose the challenge of generating motions that are stable; the second being the robustness against uncertainties in the model parameters, which will inevitably make the robot deviate from the planned trajectory.
The first part presents IS-MPC (Intrinsically Stable MPC), demonstrating its effectiveness in the stable inversion of non-minimum phase systems. We showcase the applications of IS-MPC in stabilizing balancing robots performing non-trivial navigation and loco-manipulation tasks, and in preventing the jackknife phenomenon in autonomous Tractor-Trailer vehicles.
The second part of the thesis addresses the problem of robustifying motions against parametric uncertainties, focusing on aerial robots. We make use of the recent notion of closed-loop sensitivity and explore its application for robust flight control in Quadrotors with an experimental validation. We also present a novel computationally efficient Robust MPC scheme, named ST-MPC (Sensitivity-aware Tube MPC), for controlling nonlinear systems affected by parametric uncertainties, demonstrating its effectiveness through an extensive simulation campaign.
The contributions of this thesis extend to both stability and robustness in motion generation, offering valuable insights and practical applications across diverse robotic systems
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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