31 research outputs found

    Doctor of Philosophy

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    dissertationVirtual reality is becoming a common technology with applications in fields such as medical training, product development, and entertainment. Providing haptic (sense of touch) information along with visual and audio information can create an immersive vi

    W-FYD: a Wearable Fabric-based Display for Haptic Multi-Cue Delivery and Tactile Augmented Reality

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    Despite the importance of softness, there is no evidence of wearable haptic systems able to deliver controllable softness cues. Here, we present the Wearable Fabric Yielding Display (W-FYD), a fabric-based display for multi-cue delivery that can be worn on user's finger and enables, for the first time, both active and passive softness exploration. It can also induce a sliding effect under the finger-pad. A given stiffness profile can be obtained by modulating the stretching state of the fabric through two motors. Furthermore, a lifting mechanism allows to put the fabric in contact with the user's finger-pad, to enable passive softness rendering. In this paper, we describe the architecture of W-FYD, and a thorough characterization of its stiffness workspace, frequency response and softness rendering capabilities. We also computed device Just Noticeable Difference in both active and passive exploratory conditions, for linear and non-linear stiffness rendering as well as for sliding direction perception. The effect of device weight was also considered. Furthermore, performance of participants and their subjective quantitative evaluation in detecting sliding direction and softness discrimination tasks are reported. Finally, applications of W-FYD in tactile augmented reality for open palpation are discussed, opening interesting perspectives in many fields of human-machine interaction

    Design and characterization of a fabric-based softness display

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    To enable a realistic tactile interaction with remote or virtual objects, softness information represents a fundamental property to be rendered via haptic devices. What is challenging is to reduce the complexity of such an information as it arises from contact mechanics and to find suitable simplifications that can lead an effective development of softness displays. A possible approach is to surrogate detailed tactile cues with information on the rate of spread of the contact area between the object and the finger as the contact force increases, i.e. force/area relation. This paradigm is called contact area spread rate. In this paper we discuss how such a paradigm has inspired the design of a tactile device (hereinafter referred to as Fabric Yielding Display, FYD-2), which exploits the elasticity of a fabric to mimic different levels of stiffness, while the contact area on the finger indenting the fabric is measured. In this manner, the FYD-2 can be controlled to reproduce force-area characteristics. In this work, we describe the FYD-2 architecture and report a psychophysical characterization. FYD-2 is shown to be able to accurately reproduce force-area curves of typical objects and to enable a reliable softness discrimination in human users

    Haptics Rendering and Applications

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    There has been significant progress in haptic technologies but the incorporation of haptics into virtual environments is still in its infancy. A wide range of the new society's human activities including communication, education, art, entertainment, commerce and science would forever change if we learned how to capture, manipulate and reproduce haptic sensory stimuli that are nearly indistinguishable from reality. For the field to move forward, many commercial and technological barriers need to be overcome. By rendering how objects feel through haptic technology, we communicate information that might reflect a desire to speak a physically- based language that has never been explored before. Due to constant improvement in haptics technology and increasing levels of research into and development of haptics-related algorithms, protocols and devices, there is a belief that haptics technology has a promising future

    Modulating the Perceived Softness of Real Objects Through Wearable Feel-Through Haptics

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    In vision, Augmented Reality (AR) allows the superposition of digital content on real-world visual information, relying on the well-established See-through paradigm. In the haptic domain, a putative Feel-through wearable device should allow to modify the tactile sensation without masking the actual cutaneous perception of the physical objects. To the best of our knowledge, a similar technology is still far to be effectively implemented. In this work, we present an approach that allows, for the first time, to modulate the perceived softness of real objects using a Feel-through wearable that uses a thin fabric as interaction surface. During the interaction with real objects, the device can modulate the growth of the contact area over the fingerpad without affecting the force experienced by the user, thus modulating the perceived softness. To this aim, the lifting mechanism of our system warps the fabric around the fingerpad in a way proportional to the force exerted on the specimen under exploration. At the same time, the stretching state of the fabric is controlled to keep a loose contact with the fingerpad. We demonstrated that different softness perceptions for the same specimens can be elicited, by suitably controlling the lifting mechanism of the system

    Requirements for a tactile display of softness

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    Developing tactile displays is an important aspect of improving the realism of feeling softness in laparoscopic surgery. One of the major challenges of designing a tactile display is to understand how the perception of touch can be perceived with differences in material properties. This project seeks to address this limitation by investigating how the interaction of material properties affects perception of softness and to present the perception of softness through a tactile display. The first aim explores how the interaction of material properties affects perception of softness through the use of two psychophysical experiments. Experiments used a set of nine stimuli representing three materials of different compliance, with three different patterns of surface roughness or with three different coatings of stickiness. The results indicated that compliance affected perception of softness when pressing the finger, but not when sliding; and that compliance, friction and thermal conductivity all influenced the perception of softness. To achieve the second aim of reproducing various levels of softnesses, the tactile display was built at the University of Leeds. The displayed softness was controlled by changing the contact area and tension of a flexible sheet. Psychophysical experiments were conducted to evaluate how well humans perceive softness through the display. The data was analysed using MatLab to plot psychometric functions. The results indicated that the tactile display might be good for some applications which need to compare between simulated softnesses, but it might be insufficient for other applications which need to compare between simulated softness and real samples

    On the Role of Haptic Synergies in Modelling the Sense of Touch and in Designing Artificial Haptic Systems

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    This thesis aims at defining strategies to reduce haptic information complexity, with minimum loss of information, to design more effective haptic interfaces and artificial systems. Nowadays, haptic device design can be complex. Moreover, the artificial reproduction of the full spectrum of haptic information is a daunting task and far to be achieved. The central idea of this work is to simplify this information by exploiting the concept of synergies, which has been developed to describe the covariation patterns in multi-digit movements and forces in common motor tasks. Here I extend and exploit it also in the perceptual domain, to find projections from the heterogeneous information manifold, generated by the mechanics of touch, and what can be actually perceived by humans. In this manner, design trade-off between costs, feasibility and quality of the rendered perception can be individuated. With this as motivation, referring to cutaneous sensing, I discuss the development of a fabric-based softness display inspired by ``Contact Area Spread Rate'' hypothesis as well as the characterization of an air-jet lump display method for Robot-assisted Minimally Invasive Surgery. Considering kinaesthesia, I analyze the problem of hand posture estimation from noisy and limited in number measures provided by low cost hand pose sensing devices. By using the information about how humans most frequently use their hands, system performance is enhanced and optimal system design enabled. Finally, an integrated device, where a conventional kinaesthetic haptic display is combined with a cutaneous softness one, is proposed, showing that the fidelity by which softness is artificially rendered increases

    Haptics: Science, Technology, Applications

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    This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

    Haptics: Science, Technology, Applications

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    This open access book constitutes the proceedings of the 12th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2020, held in Leiden, The Netherlands, in September 2020. The 60 papers presented in this volume were carefully reviewed and selected from 111 submissions. The were organized in topical sections on haptic science, haptic technology, and haptic applications. This year's focus is on accessibility
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