QuadStretcher: A Forearm-Worn Skin Stretch Display for Bare-Hand Interaction in AR/VR

TL;DR

QuadStretcher is a novel forearm-worn skin stretch display that enhances haptic feedback for bare-hand AR/VR interactions, outperforming existing solutions in realism and force expression through a compact, multi-unit design.

Contribution

This work introduces QuadStretcher, a new skin stretch device with four independent units that improves haptic feedback without bulky grounding, advancing bare-hand AR/VR interaction technology.

Findings

QuadStretcher outperforms Squeezer in force direction expression.

Participants reported increased realism with QuadStretcher.

Design insights inform future forearm-haptic system development.

Abstract

The paradigm of bare-hand interaction has become increasingly prevalent in Augmented Reality (AR) and Virtual Reality (VR) environments, propelled by advancements in hand tracking technology. However, a significant challenge arises in delivering haptic feedback to users' hands, due to the necessity for the hands to remain bare. In response to this challenge, recent research has proposed an indirect solution of providing haptic feedback to the forearm. In this work, we present QuadStretcher, a skin stretch display featuring four independently controlled stretching units surrounding the forearm. While achieving rich haptic expression, our device also eliminates the need for a grounding base on the forearm by using a pair of counteracting tactors, thereby reducing bulkiness. To assess the effectiveness of QuadStretcher in facilitating immersive bare-hand experiences, we conducted a comparative user evaluation (n = 20) with a baseline solution, Squeezer. The results confirmed that QuadStretcher outperformed Squeezer in terms of expressing force direction and heightening the sense of realism, particularly in 3-DoF VR interactions such as pulling a rubber band, hooking a fishing rod, and swinging a tennis racket. We further discuss the design insights gained from qualitative user interviews, presenting key takeaways for future forearm-haptic systems aimed at advancing AR/VR bare-hand experiences.