OnArmQWERTY: An Empirical Evaluation of On-Arm Tap Typing for AR HMDs

Text entry is an essential and frequent task in Augmented Reality (AR) applications, yet developing an effective and user-friendly method remains a challenge. This paper introduces OnArmQWERTY, a text entry technique for AR HMDs that allows users to project a virtual QWERTY keyboard onto various locations on their non-dominant hand, including the palm, the back of the hand, and both the anterior and posterior sides of the forearm. Users interact with this overlaid keyboard on their skin by tapping with the index finger of the dominant hand, benefiting from the inherent self-haptic feedback of on-body interaction. A user study involving 13 participants evaluated the performance of OnArmQWERTY compared to a traditional mid-air virtual keyboard. The results demonstrate that OnArmQWERTY significantly improves typing speed and accuracy. Specifically, typing on the palm location outperforms all other on-arm locations, achieving a mean typing speed of 20.18 WPM and a mean error rate of 0.71%, which underscores the importance of comfortable, ergonomic typing postures and effective tactile feedback as key factors enhancing text entry performance.