Validating a novel approach to rendering fingertip contact sensations

Fingertip haptics refers to the direct exploration of a virtual environment with the fingertips, rather than via an intermediate grasped object, such as a stylus or thimble. We hypothesize that a key psychophysical aspect of fingertip haptics is the relative motion - slip - that occurs between the fingertip, and surface. This paper investigates a novel approach to rendering slip at the finger pad. Our approach uses a rotating drum or sphere to render the velocity of a surface as it passes beneath the fingertip. We construct a prototype device in one degree of freedom and test two groups of 14 subjects on their ability to sense the nature of the fingertip contact sensation (i.e., whether an actual surface or a rotating drum renders the contact sensation). The experimental results show strong justification of our mechanical approach to rendering relative velocity at the fingertip. The results also raise several key issues for investigation in subsequent studies including the roles of vibration and apparatus dynamics.