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

2025-11-26

AI Summary

AR/VR bare-handed interaction suffers from the absence of haptic feedback, while existing solutions are constrained by base dependency and wearable burden. This paper proposes QuadStretcher, a base-free, forearm-mounted skin-stretch haptic display. It employs four independently actuated stretch units integrated with reaction-force actuators to eliminate ground-reaction requirements, enabling lightweight, high-degree-of-freedom force feedback. Leveraging precision mechanical design and programmable control, QuadStretcher delivers directional, dynamic, multi-degree-of-freedom (3-DoF) force rendering across the forearm. A user study (n=20) demonstrates that QuadStretcher significantly outperforms the squeeze-based device Squeezer in both force-direction identification accuracy and perceived realism, effectively enhancing interactive experiences such as pulling, hooking, and swinging motions.

Technology Category

• Humans and AI: Interaction Techniques and Devices
• Intelligent Robots: Manipulation
• Knowledge Representation and Reasoning: Qualitative Reasoning

Application Category

• Responsible Web: Machine-in-the-loop, human agency and autonomy
• Search and Retrieval-Augmented AI: Personalized, context-aware and across-device search
• User Modeling, Personalization and Recommendation: Fairness-aware retrieval and ranking

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.

Problem

• Providing haptic feedback for bare-hand AR/VR interaction challenges
• Designing a forearm-worn skin stretch display without grounding base
• Enhancing realism and force direction in 3-DoF VR interactions

Innovation

• Four independent stretching units on forearm
• Counteracting tactors eliminate grounding base requirement
• Expresses force direction and enhances realism