1,720,974 research outputs found
Control strategies for a multiple degree of freedom prosthetic hand
No full textSome of the traditional methods used to control a conventional prosthetic device are described alongside the current state of new control techniques and how they may progress. The review includes implantable myoelectric sensors and describes the potential of connecting directly to the peripheral nervous system. Control methods are then deduced for each technique, where the application is a six degrees of freedom hand having integral slip, force and temperature sensors
A novel thick-film piezoelectric slip sensor for a prosthetic hand
No full textThe ability to mimic the tactile feedback exhibited by the human hand in an artificial limb is considered advantageous in the automatic control of new multifunctional prosthetic hands. The role of a slip sensor in this tactile feedback is to detect object slip and thus provide information to a controller, which automatically adjusts the grip force applied to a held object to prevent it from falling. This system reduces the cognitive load experienced by the user by not having to visually assess the stability of an object, as well as giving them the confidence not to apply unnecessarily excessive grip forces. A candidate for such a sensor is a thick-film piezoelectric sensor. The method of fabricating a thick-film piezoelectric slip sensor on a prototype fingertip is described. The construction of experimental apparatus to mimic slip has been designed and analysed to allow the coefficient of friction between the fingertip and the material in contact with the fingertip to be calculated. Finally, results show that for a coefficient of friction between the fingertip and grade P100 sandpaper of approximately 0.3, an object velocity of 0.025 ± 0.008 ms-1 was reached before a slip signal from the piezoelectric sensor was able to be used to detect slip. It is anticipated that this limiting velocity will be lowered (improved) in the intended application where the sensor electronics will be powered from a battery, connections will be appropriately screened and if necessary a filter employed. This will remove mains interference and reduce other extraneous noise sources with the consequence of an improved signal to noise ratio, allowing lower threshold values to be used in the detection software
Thick-film force and slip sensors for a prosthetic hand
No full textIn an attempt to improve the functionality of a prosthetic hand device, a new fingertip has been developed that incorporates sensors to measure temperature and grip force and to detect the onset of object slip from the hand. The sensors have been implemented using thick-film printing technology and exploit the piezoresistive characteristics of commercially available screen printing resistor pastes and the piezoelectric properties of proprietary lead-zirconate-titanate (PZT) formulated pastes. The force sensor exhibits a highly linear response to forces up to 50 N with a maximum hysteresis of less than 1.4% of full scale. When configured as a pseudo half-bridge measurement circuit, the force sensor demonstrates superior insensitivity to the position of the force on the fingertip than when configured as a classic half-bridge circuit. The force sensor response is also extremely stable with temperature, typically showing variation in the output response of less than ±0.04% over the temperature range ?10 °C to +35 °C when loaded with forces up to 10.8 N. The ability of the piezoelectric PZT vibration sensor to detect small vibrations of the cantilever, indicative of object slip, has also been demonstrated
The use of design software in biomechanical engineering; the design of a force sensitive, single degree of freedom digit for a myoelectric prosthetic hand
No full textThe use of commercially available modeling software in the design of a force sensitive, single degree of freedom finger for a myoelectric prosthetic hand is discussed. The CAD package Autodesk Inventor® [1] has been used to redesign the linkage mechanism of a pre-existing finger [2] to allow the attachment at the distal end of a cantilever beam incorporating both static and dynamic force sensors [3]. The animation features of this package have been extensively used to visualize the movement of the proposed finger link structure, ensuring an unhindered, natural anthropomorphic flexion and extension. The finite element analysis package ANSYS® has also been used to model the strain profile across the surface of the cantilever beam to assist in the optimum placement of the force sensors and to determine the effects of different methods of mechanical attachment of the beam to the distal finger link [4]. Using these software packages, we are presently in the process of designing a complete myoelectric prosthetic hand with independent control in the movement of each force sensitive finger and thumb, permitting a range of different grip postures. In the near future we anticipate commencing patient trials to test for functionality and user acceptability
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
Detection of slip from multiple sites in an artificial finger
No full textA Piezoelectric thick-film sensor is a good candidate for the extraction of information from object slip in hand prosthesis. Five slip sensors were fabricated on different linkages of an artificial hand. The signals from each sensor were compared to the output from the sensor mounted on the fingertip. An analysis of the output signals from all the sensors indicates that the linkage sensors also produce similar output signals to the fingertip sensor. In the next phase of the research, velocity and acceleration of the slipped object will be considered in the 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
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