Browsing by Author "Clark, Janelle"

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    Individualized Haptics: On relating Psychophysics, Contact Mechanics, and Physiology in Indenting and Skin Stretch Haptic Cues
    (2022-04-22) Clark, Janelle; O'Malley, Marcia K
    Wearable haptic devices are now an established research area, but we have reached a design bottleneck in saliency that persists across different modalities and mechanisms. In this work, we seek to understand the contributing factors by assessing haptic perception from an individual, rather than a group, perspective. In doing so we seek to understand the sources of unique haptic experiences between users, specifically for skin stretch and indentation. The problems that wearable haptic devices seek to address are important and timely. As the mechanical design and computational control of robots become more nuanced and dexterous and as we increasingly engage with the world through technology, haptic devices can provide a surrogate sense of touch for those controlling robots in dangerous or remote situations, as well in daily life as for an amputee to feel their environment through their prosthesis. Currently, the design and testing of haptic devices are done on large groups with set parameters and cue magnitudes, however, the sense of touch is more complex and noisy than other senses, likely due to widely varying body compositions of fat and muscle and material characteristics of the skin. In this work, we will collect information on multiple domains to look for correlations within a single set of subjects, specifically their allowable stimulus range, both perceptible and comfortable, in the normal and shear directions, psychophysical performance, contact mechanics between the skin and the haptic interface, and anthropomorphic features. We hypothesize that the allowable stimulus range varies from person to person, as well as their just-noticeable differences (JND), impacting the number of discrete stimuli they can differentiate, tested using classical psychophysical methods. We hypothesize conducting experiments in force and position control will show differences in performance and distribution across subjects. In addition, by collecting force-torque and displacement information, we use Hertzian contact models to gain insight on differences in material properties, stresses, strain, and losses between individuals. This new perspective on haptic testing opens new research questions on perception of skin stretch and indentation, considerations for device design, and a multi-faceted data set to support work in haptic simulations and contact mechanics.
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    Skin Stretch as Haptic Feedback for Upper Limb Prostheses
    (2017-08-16) Clark, Janelle; O'Malley, Marcia K
    This thesis investigates two key topics to successfully integrate a skin stretch feedback device into a transradial prosthetic system. The Rice Haptic Rocker (Rocker) is a one degree of freedom haptic device that rotates on an axis, stretching the skin to convey position information. In the first topic, the experimental assessment of the mechanical rocker design and mapping functions create steps to assess perception of users. Second, the functional efficacy of the integrated system, containing the haptic device and a prosthetic arm, is tested in two experiments showing the Rocker is useful for discriminating object sizes and identifying the presence of the cue after focusing on an unrelated task. The results of these experiments inform implentation constraints between an advanced prosthetic device and proprioceptive feedback through skin stretch. Further, the Rice Haptic Rocker can be successfully utilized as proprioceptive feedback of a prosthetic device to a human user.