Habitual static stretching is recommended in many ergonomics guidelines, but continuing this habit remains challenging to workers. We address two factors causing this difficulty: most workers lack an understanding of the appropriate mechanisms of stretching, and stretching sessions require the interruption of ongoing tasks. We propose Screen-Directed Stretching, a novel technique that supports neck stretching in extended reality (XR) workspaces without interrupting work. Our technique temporarily repositions the virtual screen that the user is focusing on, guiding them to rotate their head in yaw, pitch, and roll directions and to maintain a posture for a specific duration, thus facilitating muscle extension. Through two preliminary user studies, we developed a prototype that seamlessly switches the screen’s coordinate system between world-bound and body-bound frames of reference, balancing practical workability and good stretching guidance. A user study (N = 16) demonstrates that our technique effectively induces stretching movements while minimizing loss of task efficiency.

Drawing, writing, and painting on 2D surfaces in VR offers arbitrary interaction with virtual canvases of unlimited size. However, this advantage has not been fully exploited because physical surfaces are needed to support accurate and comfortable user interactions, and the size of such surfaces is limited. We propose Redirected Drawing, a novel methodology that applies visual manipulation to the user’s drawing movement in VR to expand the perceived surface size required for the drawing experience. To this end, this study specifically explores translation gain manipulation, where the displacement of a drawing stroke in reality is simply multiplied by a gain to represent it in VR. We conducted a user study (N = 18) to measure the noticeability, acceptability, and task performance of a simple VR line-tracing task under different gain and input methods (i.e., finger in mid-air, finger on surface, pen on surface). Our results show that pen-based drawing on a physical surface allows for a gain of up to 1.16 without being noticed by the user, which is more suited to expanding a virtual canvas size than finger-based drawing on a physical surface or in mid-air. Furthermore, we show that user acceptability of the gain manipulation could be estimated by a model using the subjective discrepancy caused by the gain. Results for this model suggest that users could accept gains of up to 1.30. Based on our results, we derive guidelines for the effective use of gain manipulation.

In room-scale virtual reality, providing continuous haptic feedback from touching grounded objects, such as walls and handrails, has been challenging due to the user’s walking range and the required force. In this study, we propose LoopBot, a novel technique to provide continuous haptic feedback from grounded objects using only a single user-following robot. Specifically, LoopBot is equipped with a loop-shaped haptic prop attached to an omnidirectional robot that scrolls to cancel out the robot’s displacement, giving the user the haptic sensation that the prop is actually fixed in place, or “grounded.” We first introduce the interaction design space of LoopBot and, as one of its promising interaction scenarios, implement a prototype for the experience of walking while grasping handrails. A performance evaluation shows that scrolling the prop cancels 77.5% of the robot’s running speed on average. A preliminary user test (N = 10) also shows that the subjective realism of the experience and the sense of the virtual handrails being grounded were significantly higher than when the prop was not scrolled. Based on these findings, we discuss possible further development of LoopBot.

We examine the effect of auditory cues occurring in reality on redirection. Specifically, we set two hypotheses: the auditory cues emanating from fixed positions in reality (Fixed sound, FS) increase the noticeability of redirection, while the auditory cues whose positions are manipulated consistently with the visual manipulation (Redirected sound, RDS) decrease the noticeability of redirection. To verify these hypotheses, we implemented an experimental environment that virtually reproduced FS and RDS conditions using binaural recording, and then we conducted a user study ( N=18) to investigate the detection thresholds (DTs) for rotational manipulation and the sound localization accuracy of the auditory cues under FS and RDS, as well as the baseline condition without auditory cues (No sound, NS). The results show, against the hypotheses, FS gave a wider range of DTs than NS, while RDS gave a similar range of DTs to NS. Combining these results with those of sound localization accuracy reveals that, rather than the auditory cues affecting the participants' spatial perception in VR, the visual manipulation made their sound localization less accurate, which would be a reason for the increased range of DTs under FS. Furthermore, we conducted a follow-up user study ( N=11) to measure the sound localization accuracy of FS where the auditory cues were actually placed in a real setting, and we found that the accuracy tended to be similar to that of virtually reproduced FS, suggesting the validity of the auditory cues used in this study. Given these findings, we also discuss potential applications.

Jumping onto steps is a promising action for creating an instant height movement in VR, but installing physical steps is impractical. We propose PseudoJumpOn, a novel locomotion technique using a common VR setup that allows the user to experience virtual step-up jumping motion by applying two types of viewpoint-manipulation methods to a physical jump on a flat floor. The core idea is to replicate the physical characteristics of ascending jumps, and thus we designed two viewpoint-manipulation methods: gain manipulation, which differentiates the ascent and descent height, and peak shifting, which delays the peak timing. We conducted a user study asking participants (N = 20) to experience two-legged step-up jumps onto 0.2–0.8-m heights in VR as the two methods were applied in combination (gain manipulation: five conditions where the ascending gain was 1.0–5.0; peak shifting: four conditions where the peak timing in VR was delayed by 0–1.0 ratios of the original timing). The results showed that the participants in most conditions felt positively in terms of reality and naturalness of actually jumping onto steps, even though knowing no physical steps existed. In addition, subsequent analyses also derived practical guidelines for determining the appropriate gains and the potential use of peak shifting to achieve a natural step-up jumping experience.