Design of a smart-ring based on skin-drag motions for expressive haptic feedback

Abstract

Smart rings are an emerging wearable technology particularly suitable for discrete notifications based on haptic cues. Previous work mostly focused on tactile actuators that stimulate only specific skin receptors on the finger, resulting in limited information expressiveness. We conducted three studies, two pilot test, one survey and one design workshop with total of 111 participants and 8 designers. As a result, we propose tactoRing, a novel tactile display that, by dragging a small tactor on the skin around the finger, excites multiple skin areas resulting in more accurate cue recognition and haptic feedback guideline. In this research, we first present the hardware and a perception study to understand the ability of users to recognize eight distinct points around the finger. Moreover, we show two different techniques to encode information through skin-dragging motion with accuracy up to 94%. Based on the result, we asked designers to create dragging motions using changes of speed, direction and length. We then tested the generated skin-dragging motions with a tactoRing, classified them and extracted guidelines that can be used to convey rich and informative feedback on the fingers. We finally suggest a set of applications that, by combining sequences of tactile stimuli, achieve higher expressiveness than prior methods.