Institut des Systèmes Intelligents
et de Robotique





Tremplin CARNOT Interfaces



Thesis Title : Reproduction of Tactual Textures: Transducers, Mechanics, and Signal Encoding

Keywords : tactual roughness rendering, tactile devices, fingertip biomechanics, psychophysics of perception


Date et Location :

19/10/2011  à 16h30
UPMC – Campus Jussieu, 4 Place Jussieu - 75005 Paris
Tour 55, 2ème étage, couloir 55-65, salle 211

Abstract :
The textures of surfaces are tactually perceived mostly from the vibrations generated when sliding our fingertips on them. Despite its prevalence in everyday behavior, the study of the interaction of a finger with a textured surface, for virtual reality purposes, has not been much studied. This thesis explores some factors that contribute to the mechanics of interaction between a bare finger and a surface with a view to their artificial reproduction.
The recording and reproduction of tactual textures are first discussed, along with a specifically designed apparatus able to precisely measure the interaction force arising from the friction of a sliding finger. The same piezoelectric-based apparatus was employed to rapidly deform the fingertip during exploratory movement, in order to replicate the presence of a texture, resulting in a new approach to simulate the roughness and texture of virtual surfaces.
The problem of recording-reproducing textured surfaces motivated the question of the determination of the mechanical behavior of the fingertip. Investigations revealed that fingertips behave like elastic springs at low frequencies, and that after a corner frequency of about 100 Hz, the response is dominated by viscous damping, something that was never directly shown before.
Next, the features of the vibratory signals created by the friction of a finger on various textures were analyzed. Expressing the fluctuations of the frictional force as function of space, rather than of time, indicated a number of possible signal characteristics that could play a key role in the tactual perception textures.
The thesis highlights the importance of the mechanics and biomechanics during the haptic exploration of surfaces and their possible contribution to perception. Collectively, the findings reported in this thesis are pertinent to the design of effective virtual reality systems and other applications.