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.
https://doi.org/10.1145/3654777.3676389
We propose JetUnit, a water-based VR haptic system designed to produce force feedback with a wide spectrum of intensities and frequencies through water jets. The key challenge in designing this system lies in optimizing parameters to enable the haptic device to generate force feedback that closely replicates the most intense force produced by direct water jets while ensuring the user remains dry. In this paper, we present the key design parameters of the JetUnit wearable device determined through a set of quantitative experiments and a perception study. We further conducted a user study to assess the impact of integrating our haptic solutions into virtual reality experiences. The results revealed that, by adhering to the design principles of JetUnit, the water-based haptic system is capable of delivering diverse force feedback sensations, significantly enhancing the immersive experience in virtual reality.
https://doi.org/10.1145/3654777.3676440
We propose Selfrionette, a controller that uses fingertip force input to drive avatar movements in virtual reality (VR). This system enables users to interact with virtual objects and walk in VR using only fingertip force, overcoming physical and spatial constraints. Additionally, by fixing users' fingers, it provides users with counterforces equivalent to the applied force, allowing for diverse and wide dynamic range haptic feedback by adjusting the relationship between force input and virtual movement. To evaluate the effectiveness of the proposed method, this paper focuses on hand interaction as a first step. In User Study 1, we measured usability and embodiment during reaching tasks under Selfrionette, body tracking, and finger tracking conditions. In User Study 2, we investigated whether users could perceive haptic properties such as weight, friction, and compliance under the same conditions as User Study 1. Selfrionette was found to be comparable to body tracking in realism of haptic interaction, enabling embodied avatar experiences even in limited spatial conditions.
https://doi.org/10.1145/3654777.3676409
Real-world impact, such as hitting a tennis ball and a baseball, generates instantaneous, directional impact forces. However, current ungrounded force feedback technologies, such as air jets and propellers, can only generate directional impulses that are 10x-10,000x weaker. We present SpinShot, a flywheel-based device with a solenoid-actuated stopper capable of generating directional impulse of 22Nm in 1ms, which is more than 10x stronger than prior ungrounded directional technologies. Furthermore, we present a novel force design that reverses the flywheel immediately after the initial impact, to significantly increase the perceived magnitude. We conducted a series of two formative, perceptual studies (n=16, 18), followed by a summative user experience study (n=16) that compared SpinShot vs. moving mass (solenoid) and vs. air jets in a VR baseball hitting game. Results showed that SpinShot significantly improved realism, immersion, magnitude (p < .01) compared to both baselines, but significantly reduced comfort vs. air jets primarily due to the 2.9x device weight. Overall, SpinShot was preferred by 63-75% of the participants.
https://doi.org/10.1145/3654777.3676433