Virtual Reality (VR) emphasizes immersive experiences, while text entry often requires hands or visual attention, which may disrupt the interaction flows in VR. We present AnkleType, a hand- and eye-free text-entry technique that leverages ankle-based gestures for both standing and sitting situations. We began with two preliminary studies: one investigated the movement range of users' ankles, and the other elicited user-preferred ankle gestures for text-entry-related operations. The findings of these two studies guided our design of AnkleType. To optimize AnkleType's keyboard layout for eye-free input, we conducted a user study to capture the users' natural ankle spatial awareness with a computer-simulated language test. Through a pairwise comparison study, we designed a bipedal input strategy for sitting (BPSit) and a unipedal input strategy for standing (UPStand). Our first in-VR text-entry evaluation with 16 participants demonstrated that our methods could support the average typing speed from 8.99 WPM (BPSit) to 9.13 WPM (UPStand) for our first-time users. We further evaluated our design with a 7-day longitudinal study with twelve participants. Participants achieved an average typing speed of 15.05 WPM with UPStand and 16.70 WPM with BPSit in the visual condition, and 11.15 WPM and 12.87 WPM, respectively in the eyes-free condition.

翻译：虚拟现实（VR）强调沉浸式体验，而文本输入通常需要手部操作或视觉注意力，这可能会破坏VR中的交互流畅性。我们提出AnkleType，一种无需手眼参与的文本输入技术，利用基于脚踝的手势支持站立和坐姿两种场景。我们从两项初步研究开始：一项探究用户脚踝的运动范围，另一项则征集用户偏好的与文本输入操作相关的脚踝手势。这两项研究的结果指导了AnkleType的设计。为优化AnkleType用于免视觉输入的键盘布局，我们进行了一项用户研究，通过计算机模拟语言测试捕捉用户对脚踝空间方位的自然感知。通过成对比较研究，我们设计了坐姿双足输入策略（BPSit）和站姿单足输入策略（UPStand）。首次在VR中的文本输入评估（16名参与者）表明，我们的方法能支持首次用户平均打字速度从8.99 WPM（BPSit）到9.13 WPM（UPStand）。我们进一步通过为期7天的纵向研究（12名参与者）评估了设计。在有视觉条件下，参与者使用UPStand和BPSit的平均打字速度分别达到15.05 WPM和16.70 WPM；在免视觉条件下，分别达到11.15 WPM和12.87 WPM。