We present the Finger-Mounted Extending Rod, a wearable device that transforms fingers into virtual tools by modulating fingertip mass distribution. We employ linear actuators on fingers that extend or retract metal rods according to their poses, generating rotational inertia while redirecting the hand to natural grip postures. Through three user studies, we evaluate (1) finger pose embodiment under visual redirection and tool matching via inertia tensor similarity, (2) perception of tool length and rotational inertia, and (3) VR tool interaction experience. Results show that 10 of 15 finger poses maintained embodiment, exhibiting inertia tensor similarities of 0.936–0.991 with their matched tools and yielding perceived inertia amplifications of 4.19–10.45×; moreover, aligning inertia tensors to virtual tools enhanced immersion, realism, and enjoyment compared to misaligned or no-device conditions across six VR scenarios. We conclude by discussing how the system renders virtual tools through the fingers and enhances their perception with inertia modulation.

CHI ’25, Yokohama, Japan

In-car VR applications typically synchronize virtual motion with real vehicle movement to minimize visual-vestibular mismatch. However, this approach limits virtual movement to directions in which the vehicle can physically move, typically restricting the experience to horizontal motion. This study introduces a method to expand the range of virtual motion by simulating vertical movement, leveraging vehicle acceleration to induce a vertical pitch illusion via manipulation of gravitoinertial perception. We conducted a two-phase study evaluating (1) optimal vertical gain values for maximizing perceptual realism in a controlled environment and (2) user experience factors such as motion sickness and presence in an on-road VR flight simulation under realistic driving conditions. Our findings show that users tend to prefer vertical gains that exceed theoretically valid mappings, and highlight the importance of aligning virtual motion with perceived inertial cues to enhance the realism and coherence of vertical motion in in-car VR applications.

This study presents ErgoPulse, a system that integrates biomechanical simulation with electrical muscle stimulation (EMS) to provide kinesthetic force feedback to the lower-body in virtual reality (VR). ErgoPulse features two main parts: a biomechanical simulation part that calculates the lower-body joint torques to replicate forces from VR environments, and an EMS part that translates torques into muscle stimulations. In the first experiment, we assessed users’ ability to discern haptic force intensity and direction, and observed variations in perceived resolution based on force direction. The second experiment evaluated ErgoPulse’s ability to increase haptic force accuracy and user presence in both continuous and impulse force VR game environments. The experimental results showed that ErgoPulse’s biomechanical simulation increased the accuracy of force delivery compared to traditional EMS, enhancing the overall user presence. Furthermore, the interviews proposed improvements to the haptic experience by integrating additional stimuli such as temperature, skin stretch, and impact.

This study introduces "Flip-Pelt," a motor-driven peltier device designed to provide rapid thermal stimulation and congruent pressure feedback in virtual reality (VR) environments. Our system incorporates eight motor-driven peltier elements, allowing for the flipping of preheated or cooled elements to the opposite side. In evaluating the Flip-Pelt device, we assess user ability to distinguish between heat/cold sources by their patterns and stiffness, and its impact on enhancing haptic experiences in VR content that involves contact with various thermal sources. Our findings demonstrate that rapid thermal stimulation and congruent pressure feedback provided by Flip-Pelt enhance the recognition accuracy of thermal patterns and the stiffness of virtual objects. These features also improve haptic experiences in VR scenarios through their temporal congruency between tactile and thermal stimuli. Additionally, we discuss the scalability of the Flip-Pelt system to other body parts by proposing design prototypes.

Surreal experience in virtual reality (VR) occurs when visual experience is accompanied by congruent somatosensation. Thus, VR contents that require physical actions are often bounded to our physical capabilities to maintain somatosensory consistency. Alternatively, users often choose less immersive but safer interfaces that offer a wider action variability. In either case, this situation compromises the potential for a hyper-realistic experience. To address this, we introduce “Giant Finger,” a concept that replicates human lower body movements through two enlarged virtual fingers in VR. Through a user study, we affirmed Giant Finger’s ownership using proprioceptive drift and questionnaire responses. We also compared Giant Finger’s capability to perform a variety of tasks with existing methods. Despite its minimalistic approach, Giant Finger demonstrated a high level of efficacy in supporting lower body movements, with ownership and presence comparable to those of the body-leaning method with whole-body motion. Giant Finger can replace the sensations of real legs or support locomotion in confined spaces by providing proprioceptive illusions to the virtual lower body. The applications showcased in this paper suggest that Giant Finger can enable new forms of movement with high action variability and immersion in various fields such as gaming, industry, and accessibility.

The unique aquatic nature of swimming makes it difficult to use social or technical strategies to mitigate the tediousness of monotonous exercises. In this study, we propose the use of a smartphone-based multiplayer exergame named MobyDick . MobyDick is designed to be played while swimming, where a team of swimmers collaborate to hunt down a virtual monster. To this end, we take into account both human factors and technical challenges under swimming contexts. First, we perform a comparative analysis of a variety of wireless networking technologies in the aquatic environment and identify various technical constraints on wireless networking. Second, we develop a swimming activity recognition system to enable precise and real-time game inputs. Third, we devise a multiplayer game design by employing the unique interaction mode viable in an underwater environment, where the abilities of human communication are highly limited. Finally, we prototype MobyDick on waterproof off-the-shelf Android phones, and we deploy it in real swimming pool environments ( n = 8). Our qualitative analysis of user interview data reveals certain unique aspects of multiplayer swimming games.

The unique aquatic nature of swimming makes it very difficult to use social or technical strategies to mitigate the tediousness of monotonous exercises. In this study, we propose MobyDick, a smartphone-based multi-player exergame designed to be used while swimming, in which a team of swimmers collaborate to hunt down a virtual monster. In this paper, we present a novel, holistic game design that takes into account both human factors and technical challenges. Firstly, we perform a comparative analysis of a variety of wireless networking technologies in the aquatic environment and identify various technical constraints on wireless networking. Secondly, we develop a single phone-based inertial and barometric stroke activity recognition system to enable precise, real-time game inputs. Thirdly, we carefully devise a multi-player interaction mode viable in the underwater environment highly limiting the abilities of human communication. Finally, we prototype MobyDick on waterproof off-the-shelf Android phones, and deploy it to real swimming pool environments (n = 8). Our qualitative analysis of user interview data reveals certain unique aspects of multi-player swimming games.