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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

Development of a touch stimulator for functional magnetic-resonance imaging

Alhussain, Amer Qassim Mallah January 2013 (has links)
A tactile display system has been built with 25 contactors in a 5 × 5 array with 2mm spacing, designed to stimulate the fingertip. The drive mechanism for each contactor is a piezoelectric bimorph, allowing the display to use in functional magnetic resonance imaging experiments (fMRI). The amplitude and frequency of stimulation can be pre-set, and each contactor can be activated separately using a personal computer. The tactile produce a wide variety of time-varying spatial patterns of touch stimulation. The sensation is “natural” and the participants do not find the experience unpleasant. The psychophysics experiment and the first fMRI experiment involved identification of various patterns on the display: the tactile stimulus was stationary or moved in a circle or in a “random” trajectory with no obvious shape. Response was by push buttons. The second fMRI experiment focused on the relationship between the speed of tactile motion and the corresponding activation in the brain, using stimuli moving in a circular trajectory on the tactile display at various speeds in the range 2.9 to 77.9 mm s –1. In the psychophysics experiment, the mean identification score was 80% after only a few minutes’ practice. The results of the first fMRI experiment showed highly significant activations in primary and secondary somatosensory cortices for contrasts of circle or random stimuli with the rest condition; low significant activations in SI and SII were observed for the contrast of stationary stimuli with rest. Broca's area was found to be activated for circle and random stimulation but not for stationary stimulation. Results from the second fMRI experiment showed small speed-sensitive activations in the left side of the brain, mostly in the primary somatosensory cortex. The conclusion in present study was our tactile system can produce different types of tactile patterns and it works inside MRI scanner.
2

DEVELOPMENT OF VIRTUAL 3D TACTILE DISPLAY BASED ON ELECTROMAGNETIC LOCALIZATION

Deng, Kai January 2009 (has links)
This dissertation describes the development of an assist-device aimed to deliver 3D graphic information to the visually impaired people. A human-in-loop approach was used to analyze whether a virtual 3D shape can be transferred correctly to the human users.The proposed device in this dissertation consists of two major parts: (a) A system of position sensors for real time localization based on magnetization, and (b) A single vibratory actuator working at varied frequencies based on its real time location. The error bound of the position measurement was tested to be 2 mm, which defined the machine resolution of the shape display. In order to realize the refresh rate of the localization that can follow user's scanning speed, the parallel data processing sequences for computer and microcontroller were designed. Additionally, vibratory electromagnetic (EM) actuators were discussed based on eddy current and permanent magnet methods. The simulation study showed that eddy current method was not applicable for millimeter size coil. Accordingly, the permanent magnet method was developed and the force detection threshold of human tactile perceptions was studied.Virtual shape perception experiments were made with participation of 3 volunteers who were not aware of the 3D shape information prior to the tests. Based on the four sets of shape tests, we conclude that the majority of the shape information is able to be delivered to users by using the proposed device. Difficulties for perceiving the local sharp profile e.g. thin plates and large curvature in small shapes may be better addressed by multiple actuators simultaneously providing shape information in the local boundary detection.The major contribution of this dissertation is the 3D shape display implemented by a miniature and low cost device. The developed device utilizes both passive stimulation and active search so that a commonly used large scale actuators matrix based on mere active touch method is avoided. The studies on the required force/energy input from the actuator showed that EM actuators can be miniaturized to millimeter scale without sacrificing the ability to induce tactile stimulation. Additional uniqueness of the proposed system is the ability to present hollow features, which is impossible to display by the existing devices.
3

Bubble Driven Arrayed Actuator Device for a Tactile Display

Ukai, S., Imamura, T., Shikida, M., Sato, K. January 2007 (has links)
No description available.
4

Tactile displays for pedestrian navigation

Srikulwong, Mayuree January 2012 (has links)
Existing pedestrian navigation systems are mainly visual-based, sometimes with an addition of audio guidance. However, previous research has reported that visual-based navigation systems require a high level of cognitive efforts, contributing to errors and delays. Furthermore, in many situations a person’s visual and auditory channels may be compromised due to environmental factors or may be occupied by other important tasks. Some research has suggested that the tactile sense can effectively be used for interfaces to support navigation tasks. However, many fundamental design and usability issues with pedestrian tactile navigation displays are yet to be investigated. This dissertation investigates human-computer interaction aspects associated with the design of tactile pedestrian navigation systems. More specifically, it addresses the following questions: What may be appropriate forms of wearable devices? What types of spatial information should such systems provide to pedestrians? How do people use spatial information for different navigation purposes? How can we effectively represent such information via tactile stimuli? And how do tactile navigation systems perform? A series of empirical studies was carried out to (1) investigate the effects of tactile signal properties and manipulation on the human perception of spatial data, (2) find out the effective form of wearable displays for navigation tasks, and (3) explore a number of potential tactile representation techniques for spatial data, specifically representing directions and landmarks. Questionnaires and interviews were used to gather information on the use of landmarks amongst people navigating urban environments for different purposes. Analysis of the results of these studies provided implications for the design of tactile pedestrian navigation systems, which we incorporated in a prototype. Finally, field trials were carried out to evaluate the design and address usability issues and performance-related benefits and challenges. The thesis develops an understanding of how to represent spatial information via the tactile channel and provides suggestions for the design and implementation of tactile pedestrian navigation systems. In addition, the thesis classifies the use of various types of landmarks for different navigation purposes. These contributions are developed throughout the thesis building upon an integrated series of empirical studies.
5

Tactile Working Memory And Multimodal Loading

Terrence, Peter 01 January 2008 (has links)
This work explored the role of spatial grouping, set size, and stimulus probe modality using a recall task for visual, auditory, and tactile information. The effects of different working memory (WM) loading task modalities were also examined. The Gestalt spatial organizing principle of grouping showed improvements in response times for visual and tactile stimulus probes with large set sizes and apparently allowed participants to effectively chunk the information. This research suggests that tactile information may use spatial characteristics typically associated with visual information, as well as sequential characteristics normally associated with verbal information. Based on these results, a reformulation of WM is warranted to remove the constraints of the input modality on processing types. The input modalities appear to access both a spatial sketchpad and a temporally-based sequence loop. Implications for multisensory research and display design are discussed.
6

Intermodale Displays auf Basis intrinsisch aktiver Polymere

Paschew, Georgi 10 November 2021 (has links)
Der in dieser Arbeit verfolgte Ansatz ermöglicht die generelle Herstellung taktiler Displays mit fotolithographischen Methoden. Dabei werden alle Aktorelemente Schicht für Schicht und gleichzeitig während des Herstellungsprozesses erzeugt. Somit ist eine Miniaturisierung und Skalierung möglich, wie sie für Prozesse in der Halbleitertechnik üblich ist. Um die Aktorgröße jedes einzelnen Aktors zu kontrollieren, wurde das temperatursensitive Hydrogel Poly(N-Isopropylacrylamid) verwendet und zur Steuerung eine elektronikkompatible thermische Schnittstelle entwickelt. Dabei entsteht ein hochaufgelöstes thermisches Feld, welches aktorgenau den Zustand von jedem visuellen Pixel und taktilem Taxel einstellt. Es wurde ein System zur Wiedergabe von sowohl glatten als auch rauen Oberflachen und ein weiteres System zur Wiedergabe von Konturen aufgebaut. Da die Aktoren ihre optischen Eigenschaften verändern, haben die Displays damit zusätzlich auch eine visuelle, monochrome Funktionalität.:1 Einleitung 2 Präzisierte Problemstellung 3 Stand der Technik 3.1 Haptik 3.2 Kutane Displays 3.3 Taktile Wahrnehmung als Grundlage kutaner Displays 3.3.1 Frequenzabhängigkeit der Hautwahrnehmung 3.3.2 Sensortypen der Haut 3.3.3 Zusammengesetzte Wahrnehmung und Wahrnehmbarkeitsschwellen 3.3.4 Auswahl des Aktorfunktionsprinzips 3.4 Grundlagen stimulisensitiver Hydrogele 3.4.1 Arten von Gelen 3.4.2 Thermodynamisches Gleichgewicht der Gelquellung 3.4.3 Quellkinetik: Zeitliche Beschreibung der Quellung 3.4.4 Herstellung von Hydrogelstrukturen 3.5 Erzeugung eines Temperaturprofils zur Aktorsteuerung 4 Herstellung des Aktorchips und Elementansteuerung 4.1 Trägersubstratherstellung 4.1.1 Trägersubstrat-Schichtaufbau: vereinfachtes Modell 4.1.2 Projektionsschicht 4.1.3 Herstellung einer transparenten Schicht definierter thermischer Eigenschaften 4.2 Aktorarrays auf Hydrogelbasis 4.3 Fotolithografischer Prozess 4.3.1 Belichtungseinheit 4.3.2 Lichtleistung und Uniformität 4.3.3 Fotolithografische Maske 4.3.4 Proximity-Belichtung – 1:1 Schattenprojektion 4.4 Hydrogelsynthese 4.4.1 Vernetzergehalt 4.4.2 Fotoinitiator 4.4.3 Losungsmittel- und Monomerkonzentration 4.4.4 Lösungsmittelqualitat und Temperatur 4.4.5 UV-Intensitat 4.4.6 Lithografische Hydrogelstrukturierung 4.4.7 UV-Belichtungszeit 4.4.8 Belichtungsprozess und Lichtleistung 4.4.9 Auswirkungen von Sauerstoff auf die Hydrogelstruktur 4.5 Strukturierungsgrenze 4.6 Haftvermittlung zwischen Hydrogelaktoren und Tragersubstrat 4.7 Thermische Aktorsteuerung 4.7.1 Temperatursteuerung im Quellungsgleichgewicht 4.7.2 Quellverhalten bei schneller Temperaturanderung und kurzer Quellzeit 4.8 Fertigungstechnologie fur Grosflächenmikrostrukturierung 4.8.1 Herstellung von Grosflächenmaster 4.8.2 Elastische Displayabdeckung 4.8.3 Mikrofluidische Quellmittelversorgung des Aktorchips 5 Optoelektrothermischer Controller 5.1 Konzept Warmesteuerung durch Licht 5.2 Aktorchip-Aufnahmeeinheit mit Licht-Wärme-Umwandlung 5.3 Mechanischer und optischer Aufbau 5.4 Zusatzoptik für Projektion auf 2,5 Zoll Displaydiagonale 5.5 Umlenkspiegel 5.6 Leistungsparameter der verwendeten Projektions-Systeme 5.7 Projektorcharakteristik 5.8 Setup der Thermografiekamera 5.9 Optimierung und Charakterisierung der Aktorsteuerung 5.9.1 Design-, Betriebs- und Messgrosen der thermischen Steuerung 5.9.2 Dimensionierung und Optimierung der thermischen Steuerung 5.9.3 Zeitliche und räumliche Auflösung der Aktorsteuerung 5.9.4 Optische Temperaturbestimmung durch Kontrastfunktion 6 Multimodales Display 6.1 Displayfunktionen 6.1.1 Basisaktorchip als Aktorarray mit Substrat und Abdeckung 6.1.2 Monochrome Displayfunktion 6.1.3 Ausgabe taktiler Oberflächeneigenschaften 6.1.4 Taktile Kantenhervorhebung der Kontur 6.2 Kombinierte Monochrom und Displacementfunktionalität 7 Zusammenfassung 8 Ausblick
7

Dispositifs d'Affichage de Sensations Tactiles à Base de Microsystèmes Électro-Mécaniques (MEMS) Magnétiques : Conception, Réalisation et Tests / Tactile Display Devices Based on Magnetic Micro-Electro-Mechanical Systems (MEMS) : Conception, Elaboration and Characterization

Streque, Jérémy 27 June 2011 (has links)
Les dispositifs de stimulation tactile sont des systèmes destinés à fournir un retour sensoriel à leurs utilisateurs. Ils enrichissent les interfaces homme-machine dans les applications de réalité virtuelle ou augmentée. Ce mémoire traite de l’apport des microsystèmes électromécaniques (MEMS) actionnés magnétiquement à la réalisation d’interfaces de stimulation tactile facilement intégrables.Un état de l’art des solutions d’actionnement mises en œuvre dans les dispositifs existants est proposé, ainsi qu'une définition des besoins pour les applications visées. Les solutions retenues sont basées sur l’actionnement magnétostatique.Les premiers prototypes d’interfaces de stimulation tactile se présentent sous la forme d'un réseau de 4x4 actionneurs élastomériques hybrides avec un pas de 2 mm, combinant microfabrication et techniques de fabrication conventionnelles. La conception et l’élaboration de ces micro-actionneurs est présentée en détail. L'actionnement impulsionnel permet d'atteindre des amplitudes de vibration importantes (jusqu'à 200 µm) et des forces élevées (32mN par actionneur). Des tests sensoriels confirment enfin leur efficacité. Des micro-bobines ont aussi été développées afin de répondre aux besoins des micro-actionneurs magnétiques, ainsi qu'au cahier des charges des interfaces de stimulation tactile. Diverses configurations de micro-bobines adaptées à l'actionnement de puissance sont proposées et réalisées par électrodéposition. Des micro-actionneurs basés sur ces bobines intégrées ont alors été réalisés, puis caractérisés. L'utilité des bobines pour les micro-actionneurs de puissance est alors discutée face aux solutions d’actionnement hybride / Tactile display devices are systems bound to provide a tactile feedback to their users. They improve human-machine interfaces in the fields of virtual or augmented reality. This report deals with the contribution of magnetically actuated micro-electro-mechanical systems (MEMS) to the elaboration of easily integrable tactile display devices.A state of the art of actuation techniques used in existing devices is proposed, along with a requirements analysis for tactile applications. Magnetostatic actuation was considered for these needs.First tactile display device prototypes are designed as a network of 4x4 hybrid elastomeric micro-actuators with a 2 mm pitch, and combined microfabrication and conventional fabrication techniques.The conception and elaboration of these micro-actuators is detailed. High vibration amplitudes can be reached using pulse actuation (up to 200 µm), with instantaneous forces of 32 mN per actuator. Sensitive tests were also achieved in order to confirm their efficiency.Micro-coils were also developed in order to fulfill the magnetic micro-actuators needs, and meet the requirements for tactile display devices. Various micro-coil configurations suitable for power actuation are proposed and elaborated by electrodeposition. Micro-actuators based on elastomeric membranes were fabricated and characterized. The contribution of these micro-coils for micro-actuation is discussed face with hybrid approaches
8

Figure and texture presentation capabilities of a tactile mouseequipped with a display pad of stimulus pins

Ohka, Masahiro, Koga, Hiroshi, Mouri, Yukihiro, Sugiura, Tokuhiro, Miyaoka, Tetsu, Mitsuya, Yasunaga 07 1900 (has links)
No description available.

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