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>Anaxagìra mànoÞnfhsiditäqeØra êqeinfronim¸tatoneÚnaitÀnz¸.wnnϑrwpon eÖlogondà di täfronim¸tatoneÚnaiqeØra lambnein. AÉ màngr qeØre îrganìn eÊsin, dà fÔsi eÈ dianèmei, kaϑper nϑrwpo frìnimo , ékaston tÀ. dunamèn¸. qr¨stai [2, 45].
Anaxagoras said it was because it has hands that mankind is the most intelligent of animals; it is correct to say that because of his intelligence he has hands. For the hands are an instrument, and nature always apportions, like an intelligent human being, each instrument to the one able to use it [42, 44].
Abstract
The aim of this Thesis is to investigate the possibility of mimicking haptic perception by using new technologies.
Innovative solutions are needed to address multi-channel tactile perception. One avenue is to use “smart fluids”, such as e.g. Magneto-Rheological Fluids. Their rheological behaviour could be exploited to implement innovative haptic interfaces, which are capable of reproducing shape and compliance of virtual objects.
Unlike kinaesthetic displays present in literature, this type of haptic interfaces would allow a direct contact with a compliant object. In this case both kinaesthetic and cutaneous channels of the fingerpads are stimulated during manipulation thus tactile perception is augmented.
To justify this approach some design considerations are discussed and several preliminary prototypes based on Magneto-Rheological Fluids are proposed and de-signed.
A new concept of haptic display for free-hand exploration is envisioned, the Haptic Black Box, which can be imagined as a box where the operator can poke his/her bare hand and interact with a virtual object by freely moving the hand
Abstract
Starting from the analysis of the previous prototypes, some detailed magnetic simulations by means of numerical code are provided in order to identify a new device with improved performance.
A 3D numerical analysis, taking into account the material non-linearity, is achieved to predict the distribution of the magnetic field and the rheological be-haviour of the fluid.
In this way some technical difficulties related to the non-linearity of the fluid and magnetic saturation, to the thermal behaviour of the coils and to the magnetic hysteresis, have been overcome.
The new design is performed acting both on the characteristics of the fluid and on a shrewd constructive approach. These improvements led to a new 3D implementation of Haptic Black Box. The HBB-II is described in terms of technical design and mechanical arrangements.
This new device enhanced performance in terms of magnitude and accuracy of magnetic field as well as increased spatial resolution.
An analysis of interactions between the operator hand and the fluid specimen is proposed with the aim of reducing the artifacts and the discontinuities on the workspace containing the fluid.
To evaluate the possibility of mimicking biological tissues softness, a descriptive model of the Magneto-Rheological Fluid able to emphasize its viscoelastic behaviour is formulated.
Furthermore, some psychophysical tests and experimental results on excited MRF specimens, in terms of softness and/or shape recognition are illustrated and discussed.
Acknowledgements
To my dear wife Lucia and to my family
I wish to express gratitude especially to my advisor Prof. Antonio Bicchi, for his guidance, encouragement and continuous support during my PhD studies.
So many people have encouraged and supported me: I would like to acknowledge their contribution by mentioning their names.
I would like to express my sincere thanks to all the Interdepartmental Research Center “E. Piaggio”, professors, researchers, colleagues and staff.
In particular many thanks to all old and new close friends E. Pasquale Scilingo, Giovanni Tonietti, Lucia Pallottino, Daniele Fontanelli, Enzo Scordio, Davide Dente, Pierpaolo Murrieri, Antonino Previti, Antonio Danesi, Riccardo Schiavi, Adriano Fagiolini, Giordano Greco, Soumen Sen, Federico Carpi, Antonio Lanat`a, Mario Tesconi, Elena Nardini, Fabia Galantini.
Acknowledgements
precious support he done in building all the hardware and mechanical equipments. This work is dedicated to my family, my father Rocco and my mother Anna Maria, for their constant support during the past years. Thanks to my dear brothers Antonio, Andrea, my sister Clelia and my cousin Vincenzo and to my all parents.
Above all, to my dear wife Lucia, who has always been there with her love, inspiration and encouragement during my research work.
Deepest thanks to my Pisa’s family: Mario Macchia, Marisa Tellini and to Lanteri’s friends.
This work was supported by the 5thFramework IST Program of the EU: Touch