196,259 research outputs found
FAST-Hex - A Morphing Hexarotor: Design, Mechanical Implementation, Control and Experimental Validation
No full textWe present FAST-Hex, a micro aerial hexarotor platform that allows to seamlessly transit from an under-actuated to a fully-actuated configuration with only one additional control input, a motor that synchronously tilts all propellers. The FAST-Hex adapts its configuration between the more efficient but under-actuated, collinear multi-rotors, and the less efficient but full-pose-tracking, which is attained by non-collinear multi-rotors. On the basis of prior work on minimal input configurable micro aerial vehicle, we mainly stress three aspects: mechanical design, motion control, and experimental validation. Specifically, we present the lightweight mechanical structure of the FAST-Hex that allows to only use one additional input to achieve configurability and full actuation in a vast state space. The motion controller receives as input any reference pose in in R3 SO(3) (3D position + 3D orientation). Full pose tracking is achieved if the reference pose is feasible with respect to actuator constraints. In case of unfeasibility, a new feasible desired trajectory is generated online giving priority to the position tracking over the orientation tracking. Finally, we present a large set of experimental results shading light on all aspects of the control of the FAST-Hex
Weighting by Iteration: The Case of Ryll-Nardzewski’s Iterations
No full textAczél’s and Ryll-Nardzewski’s dyadic iterations are iterative procedures which associate to a given mean M a family of means { Md: d∈ Dyad ([ 0 , 1 ]) } parameterized by Dyad ([ 0 , 1 ]) , the dyadic fractions of the interval [0, 1]. Aczél’s iterations exhibit a nice characteristic: when M is a strict continuous mean and x < y, the set { Md(x, y) : d∈ Dyad ([ 0 , 1 ]) } is dense in [x, y]. This fact is in the basis of the construction of an algorithm of weighting for an ample class of means. In pursuit of a similar algorithm using Ryll-Nardzewski’s instead of Aczél’s iterations, a series of obstacles is found, which motivates the detailed study of these last conducted along this paper. Among other result of interest, several conditions on the mean M are identified which make viable a weighting algorithm based on these iterations.Fil: Berrone, Lucio Renato. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Exactas, Ingeniería y Agrimensura. Escuela de Ingeniería Electrónica. Laboratorio de Acústica y Electroacústica; Argentin
Measurement instruments for the early detection of unilateral cerebral palsy and evaluation of bimanual performance
No full textInfants with early brain lesions are at risk of developing unilateral cerebral palsy (CP) and valid and reliable measurement instruments for their early detection as well as evaluation of their bimanual performance at later age are needed. Such identification allows for early family support and intervention, while evaluation of hand function at later ages enables to tackle primary challenges children and adolescents with unilateral CP face continuously while performing everyday activities that require the use of both hands. This thesis focuses on two measurement instruments, the Hand Assessment for Infants (HAI) and the Children’s Hand-use Experience Questionnaire (CHEQ), as applied to infants at risk of developing unilateral CP and children and adolescents with this condition, respectively. The overall aim was to determine the validity of HAI scores to predict unilateral CP and the ability of the CHEQ scores to capture perceptions of bimanual performance, both at a single point in time and over time, in comparison to other assessments serving as external criteria.The HAI is the first standardized test designed to evaluate both uni- and bimanual functions in infants from 3-12 months of age at risk of developing unilateral CP. In combination with neonatal magnetic resonance imaging, and considerations of gestational age and sex, the HAI can predict unilateral CP in infants with asymmetric perinatal brain injury as young as 3.5-4.5 months of age. In addition, HAI scores exhibit very good to excellent overall accuracy in predicting the development of unilateral CP in infants at risk at various time-points from 3.5-12 months of age. Impaired hand function presents a continuous challenge when performing daily activities requiring the use of both hands, especially as children with unilateral CP grow older. The CHEQ, is an online patient-reported questionnaire of how children and adolescents with unilateral hand impairment experience the use of the affected hand in connection with activities requiring both hands. The AHA is a standardized test based on observation of the use of the affected hand by children with unilateral CP during bimanual activities. The CHEQ and the AHA were found to measure different constructs that are only related to a minor extent, emphasizing the need to utilize both of these complementary tools to obtain a more complete picture of the perceived and observed performance of bimanual activities by children and adolescents with unilateral CP. The CHEQ scores captured some change in perceived bimanual performance, with good accuracy for the scale feeling bothered, but only limited accuracy for the scales grasp efficacy and time utilization. Consequently, CHEQ scores can be recommended primarily for describing perceived bimanual performance.List of scientific papersI. Early prediction of unilateral cerebral palsy in infants with asymmetric perinatal brain injury – model development and internal validation. Ryll UC*, Wagenaar N*, Verhage CH, Blennow M, de Vries LS, Eliasson AC. Eur J Paediatr Neurol. 2019;23(4):621-628. *The first and second author contributed equally to this work. https://doi.org/10.1016/j.ejpn.2019.04.004 II. Predictive validity of the Hand Assessment for Infants (HAI) in infants at risk of unilateral cerebral palsy. Ryll UC, Krumlinde-Sundholm L, Verhage CH, Sicola E, Sgandurra G, Bastiaenen CHG, Eliasson AC. [Submitted]III. Assisting Hand Assessment (AHA) and Children’s Hand-use Experience Questionnaire (CHEQ): observed versus perceived bimanual performance in children with unilateral cerebral palsy. Ryll UC, Bastiaenen CHG, Eliasson AC. Phys Occup Ther Pediatr. 2017;37(2):199-209. https://doi.org/10.1080/01942638.2016.1185498 IV. To explore the validity of change scores of the Children’s Hand-use Experience Questionnaire (CHEQ) performance in children with unilateral cerebral palsy. Ryll UC, Eliasson AC, Bastiaenen CHG, Green D. Phys Occup Ther Pediatr. 2019;39(2):168-180. https://doi.org/10.1080/01942638.2018.1438554 </p
Modeling and control of UAV bearing formations with bilateral high-level steering
No full textIn this paper we address the problem of controlling the motion of a group of unmanned aerial vehicles (UAVs) bound to keep a formation defined in terms of only relative angles (i.e. a bearing formation). This problem can naturally arise within the context of several multi-robot applications such as, e.g. exploration, coverage, and surveillance. First, we introduce and thoroughly analyze the concept and properties of bearing formations, and provide a class of minimally linear sets of bearings sufficient to uniquely define such formations. We then propose a bearing-only formation controller requiring only bearing measurements, converging almost globally, and maintaining bounded inter-agent distances despite the lack of direct metric information.The controller still leaves the possibility of imposing group motions tangent to the current bearing formation. These can be either autonomously chosen by the robots because of any additional task (e.g. exploration), or exploited by an assisting human co-operator. For this latter 'human-in-the-loop' case, we propose a multi-master/multi-slave bilateral shared control system providing the co-operator with some suitable force cues informative of the UAV performance. The proposed theoretical framework is extensively validated by means of simulations and experiments with quadrotor UAVs equipped with onboard cameras. Practical limitations, e.g. limited field-of-view, are also considered. © The Author(s) 2012
Dr. Duane M. Jackson, Morehouse College, July 2011
No full textThis video is a conversation with Dr. Duane M. Jackson. Dr. Jackson talks about his paper, "Recall and the Serial Position Effect: The Role of Primacy and Recency on Accounting Students' Performance." Jackie Daniel, AUC Woodruff Library, is the interviewer
Bilateral Shared Control : Balancing Autonomy and Human Assistance with a Group of Quadrotor UAVs
No full textIn this paper, we present a complete control frame- work and associated experimental testbed for the bilateral shared control of a group of quadrotor UAVs. This control architecture is applicable to any task and allows to integrate: i) a decen- tralized topological motion control (responsible for the mutual interactions in the UAV formation), ii) a human assistance module (allowing human intervention, whenever needed, on some aspects of the UAV group behavior), and iii) a force-feedback possibility (increasing the telepresence of the human assistants by providing suitable haptic cues informative of the UAV behavior). We will show, as worked-out case studies, how to specialize the topological motion controller to the relevant cases of constant, unconstrained and connected group topologies, and how to let a human operator intervening at the level of single UAVs or of the whole group dynamics. A detailed description of the experimental testbed is also provided with emphasis on the quadrotor UAV hardware and software architectures. Finally, the versatility of the proposed framework is demonstrated by means of experiments with real UAVs. Although quadrotors are used as actual robotic platforms, the proposed framework can be straightforwardly extended to many different kinds of UAVs with similar motion characteristics
"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States" By M. Carey.
No full text"Reflections on the subject of Emigration from Europe with a view to Settlement in the United States: containing bried sketches of the moral and political character of those states.
By M. Carey, member of the American philosophical, and of the American Antiquarian Society, and author of The Olive Branch, Cindiciae Hibernicae, essays on banking, on political economy, and on internal improvement.
To which are now added the English editor's comments on the subject; together with Important Advice to Emigrants, and Cautions Against Impositions Practiced in the Outports
Pelistega europaea gen. nov., sp. nov., a bacterium associated with respiratory disease in pigeons: taxonomic structure and phylogenetic allocation
No full textTwenty-four strains isolated mainly from infected respiratory tracts of pigeons were characterized by an integrated genotypic and phenotypic approach. An extensive biochemical examination using conventional tests and several API microtest systems indicated that all isolates formed a phenotypically homogeneous taxon with a DNA G+C content between 42 and 43 mol%. Whole-cell protein and fatty acid analysis revealed an unexpected heterogeneity which was confirmed by DNA-DNA hybridizations. Four main genotypic sub-groups (genomovars) were delineated. 16S rDNA sequence analysis of a representative strain indicated that this taxon belongs to the beta-subclass of the Proteobacteria with Taylorella equigenitalis as its closest neighbour (about 94.8 % similarity). A comparison of phenotypic and genotypic characteristics of both taxa suggested that the pigeon isolates represented a novel genus for which the name Pelistega is proposed. In the absence of differential phenotypic characteristics between the genomovars, it was preferred to include all of the isolates into a single species, Pelistega europaea, and strain LMG 10982 was selected as the type strain. The latter strain belongs to fatty acid cluster I and protein electrophoretic sub-group 1, which comprise 13 and 5 isolates, respectively. It is not unlikely that the name P. europaea will be restricted in the future to organisms belonging to fatty acid cluster I, or even to protein electrophoretic sub-group 1, upon discovery of differential diagnostic features
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Dr. Glendon Swarthout
No full textHosted by Roger M. Busfield, MSU Assistant Professor of Speech and Theater, Meet the Author is designed to introduce a general audience to a contemporary author and their work through in-depth interviews. This episode features a conversation between Dr. Glendon Swarthout, prolific author and English professor at MSU, and assistant professors Sam S. Baskett and Theodore B. Strandness
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