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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Design and evaluation of a shape memory alloy-based tendon-driven actuation system for biomimetic artificial fingers

Bundhoo, Vishalini 07 October 2009 (has links)
This thesis presents the preliminary work in the development of a biomimetic actuation mechanism for prosthetic and wearable robotic hand applications. This work investigates the use of novel artificial muscle technology, namely, shape memory alloys. The mechanism developed is based on the combination of compliant tendon cables and one-way shape memory alloy wires that form a set of agonist–antagonist artificial muscle pairs for the required flexion/extension or abduction/adduction of the finger joints. For the purpose of this thesis, an anthropomorphic four degree of freedom artificial testbed was developed with the same kinematic properties as the human finger. Hence, the size, appearance and kinematic architecture of the index finger were efficiently and practically mimicked. The biomimetic actuation scheme was implemented on the anthropomorphic artificial finger and tested, in an ad-hoc fashion, with a simple microcontroller-based pulse width modulated proportional derivation (PWD-PD) feedback controller. The tests were done to experimentally validate the performance of the actuation mechanism as emulating the natural finger’s joints movement. This thesis details the work done for the finger design process as well as the mechanisms and material used to achieve the actuation and control objectives. The results of the experiments done with the actuation platform are also presented.
2

Cartographie de la perception tactile des textures tridimensionnelles par un doigt artificiel instrumenté / Cartography of the tactile perception of three-dimensional textures by an instrumented artificial finger

Abdouni, Abdenaceur 23 January 2018 (has links)
Une régression des principales modalités sensorielles (vision, audition, goût et odorat) est bien rapportée à l'âge. La perception tactile est influencée par différents paramètres. Un grand nombre de ces paramètres ont été bien étudiés dans la littérature tels que le système nerveux central, la densité des mécanorécepteurs dans la peau et les seuils de détection vibro-tactile. Ces paramètres ont été étudiés pour comprendre l'affaiblissement de la perception tactile au fil du temps et les différences naturelles entre les hommes et les femmes. Le doigt humain est toujours utilisé pour qualifier la qualité et les propriétés d'une surface. Par conséquent, un panel de différent âge et sexe est toujours utilisé par différents secteurs industriels afin de comprendre les besoins des consommateurs. Cependant, cette méthode est très coûteuse, longue et subjective. L’objectif de ce travail était de développer une méthodologie qui permette d'avoir une objectivation tactile semblable au panel, cela signifie qu'on doit prendre en compte les effets de l'âge et du sexe. Cette thèse a fourni des mesures in vivo pour 40 doigts humains. Nos développements proposent un doigt artificiel capable de mimer le doigt humain, en tenant l’effet de l'âge et du sexe. Pour atteindre notre objectif, nous avons développé plusieurs approches qui combinent à la fois, la topographie multi-échelle du doigt humain, ces propriétés mécaniques anisotropes, les propriétés tribologiques et l’effet de l’aire réelle de contact et la direction du toucher sur la force de frottement et les vibrations générées. Le développement d’un algorithme de traitement du signal, a permis d’identifier des coefficients représentatifs de la qualité de la surface touchée. L’ingénierie de l'émotion a été un autre axe de recherche dans de ces travaux. L’instrumentation du doigt humain avec un dispositif laser-doppler, a permis d’évaluer la qualité tactile des échantillons en fonction de l'émotion générée pendant le processus du toucher. Cette émotion est étudiée par la variation fréquentielle du débit sanguin. Le mise au point d’un doigt artificiel bio-inspiré qui possède des propriétés biophysiques proches du doigt humain, a permis de réaliser un démonstrateur de toucher qui peut intégrer l’âge et le sexe d’un panel. Ce dispositif répond au cahier des charges défini dans le projet ANR «plasticTouchDevice», et permet aux industriels de la plasturgie de mener des expertises de leurs innovations en ayant recours à un dispositif qui permet d’intégrer l’effet de l’âge et du sexe dans la métrologie de la qualité du toucher des matériaux plastiques. / A decline in the main sensory modalities (vision, hearing, taste, and smell) is well reported to occur with advancing age, it is expected a similar change to occur with touch sensation and perception. The tactile perception is influenced by different parameters. Many of those parameters have been well studied in the literature such as central nervous system, the density of mechanoreceptors in the skin and the vibro-tactile detection thresholds. These parameters have been studied in order to understand the weakens of tactile perception over time and the natural differences between men and women. The human finger is always used to qualify the quality and the properties of a surface. Therefore, a panel of different age and gender always used by companies in order to understand the customers’ needs. However, this method is very expensive, time-consuming and subjective. The objective of this work is to give a solution that avoid the limits of the actual method, but in the same time it should keep their advantages (age and gender). This thesis provided in vivo measurements for 40 human fingers. Our developments propose an artificial finger capable of mimicking the human finger, taking into account the effects of age and gender. To achieve our goal, we have developed several approaches that combine the multi-scale topography of the human finger, the anisotropic mechanical properties, the tribological properties, the effect of the real contact area, the direction of touch on the friction force and the vibrations generated by the human finger. The development of a new signal processing algorithm has made it possible to identify coefficients representative of the quality of the affected surface. The engineering of emotion has been another area of research in this work. Instrumentation of the human finger with a laser Doppler device, allowed to evaluate the tactile quality of the samples according to the emotion generated during the process of the touch. This emotion is studied by the frequency variation of the blood flow. The development of a bio-inspired artificial finger that has biophysical properties close to the human finger, has made it possible to realize a haptic touch demonstrator that can integrate the age and gender of a panel. This device meets the specifications defined in the ANR project "PlasticTouchDevice", and allows plastics industry to conduct expertise of their innovations by using a device that allows the integration of the effects of age and of gender in the metrology of the quality of the touch of plastic materials.
3

Rozpoznávání živosti otisků prstů / Fingerprint Liveness Recognition

Lodrová, Dana January 2007 (has links)
This document deals with presentation of nowadays software and hardware methods used for fingerprint recognition with focus on liveness testing and thereafter it deals with description of my solution. In order to describe results obtained from study of technical literature, we discuss important terminology of biometric systems at first and further main principles of fingerprint sensors used in practice are shown. From overviewed methods of liveness detection we underline one method based on  perspiration (researched by BioSAL laboratory) and one spectroscopic method researched by Lumidigm Corporation. The study of liveness testing methods inspired me to creation of new type fingerprint sensor which has built-in livennes testing method based on two characteristic properties of living human tisue. In order to test this sensor, we discuss nowadays sensor deception method. It follows from their analysis, that newly designed sensor should be theoretically resistant to each of them.

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