Presenting Surface Features Using a Haptic Ring: A Psychophysical Study on Relocating Vibrotactile Feedback.

In the context of wearable technologies, it is often important for the fingers to be unconstrained so that they can be used to explore the environment. In this paper, we explored the feasibility of presenting vibrotactile cues that represented different textures to one of three locations on the hand and forearm using a wearable device. The first experiment indicated that vibrotactile signals of varying frequency rendered by the tactile display could be encoded by participants in terms of changes along a roughness-smoothness dimension. The differential thresholds measured for vibrotactile frequency were significantly higher on the wrist as compared to the fingerpad and the distal phalanx of the index finger. In two subsequent experiments vibrotactile signals were presented by a tactile ring worn on the distal phalanx and participants evaluated real textures explored by the fingerpad and virtual textures rendered by the ring. It was found that participants could compare and rank in terms of roughness two spatially distributed inputs with reasonable accuracy. In the context of the haptic ring being developed, these findings indicated that it is feasible to display information experienced at the fingertip on a more proximal location on the hand, thus freeing the fingers for other tasks.