Toward Eyes-Free Interaction: Whole-Arm Guidance via Fingertip Deflection with the NURing.

Abstract

Haptic feedback can convey spatial information without engaging vision or hearing, making it well suited for eyes-free and assistive applications. However, many haptic guidance systems rely on cues that require explicit cognitive interpretation, which can slow user responses and introduce ambiguity in the conveyed spatial information. To address this, we introduce fingertip deflection as a kinesthetic guidance cue via the NURing, a wearable tendon-driven device that delivers controlled fingertip deflections to guide whole-arm motion, designed to leave the fingerpad unobstructed for tactile exploration. Inspired by the instinctive response of toddlers guiding parents by the finger [1], deflection cues provide a mechanically direct and readily interpreted form of haptic guidance. Two user studies evaluated closed-loop guidance in horizontal (single-axis, Study 1) and horizontal-vertical (dual-axis, Study 2) task spaces. In singleaxis tasks, blindfolded participants reached a median endpoint error of 11.3mm in under 3 s on average, and tracked moving targets with 53.5mm mean error. In dual-axis tasks, participants accurately identified deflection cue directions, and successfully reached two-dimensional target poses with a median endpoint error of 12.6mm in under 7 s on average. Kinematic analysis revealed that participants responded rapidly (median 330 ms), with early trajectories biased within 25° toward the target heading, indicating that deflection cues provided early, actionable direction information. These results demonstrate that fingertip deflection via the NURing enables fast, readily interpreted kinesthetic guidance that produces a coordinated whole-arm response without obstructing tactile contact, supporting its potential for eyes-free interaction and assistive applications.