Shoichi Hasegawa

Wearable haptic devices face a trade-off between providing rich feedback and preserving natural fingertip sensation. Current multi-DOF systems encumber the fingerpad, interfering with fingerpad sensory capabilities, while lightweight devices offer limited 1-DOF feedback. To address this, we present a 5.24 g, three-degree-of-freedom (3-DOF) haptic device that stimulates mechanoreceptors around the fingernail, leaving the fingerpad unobstructed. It uses two string-pulling motors for distal-proximal feedback and an arc-shaped pin motor for radial-ulnar stimulation to generate directional force vectors. This approach is grounded in the physiology of directionally-sensitive slowly adapting type 2 (SA2) mechanoreceptors. Experimental results demonstrate that the proposed 3-DOF approach improves weight and friction discrimination over single-DOF pressure feedback. Moreover, it delivers directional cues during static contact, a capability absent in vibrotactile systems, and achieves higher overall user satisfaction. By preserving fingertip sensation, the proposed device enables simultaneous interaction with virtual and physical objects, making it suitable for mixed reality applications.

The olfactory display is a tool capable of generating essential olfactory feedback, and when implemented in a wearable form integrated with virtual reality (VR) hardware, it can significantly enhance immersion. However, current olfactory displays suffer from insufficiencies including limited scent generation range, inevitable latency before perception, the persistence and diffusion of previously emitted odors, and imprecise intensity control. We present an eight-channel wearable olfactory display that mounts directly on a head-mounted display (HMD) and delivers scents with minimal latency. Through precise calibration of the microfluidic channels, the system achieves nanoliter-scale liquid delivery control, generating accessible odor concentrations ranging within 1000 ppm. An active air-cleaning mechanism effectively prevents the lingering odor. Leveraging the intrinsic advantages of the wearable form and rapid odor generation technology, the system achieves a perception latency of just 3.17 s. Finally, to address heat accumulation from onboard electronics, an active thermal convection structure was implemented. This design suppresses temperature rise by 48 %, enabling its stable, long-term continuous operation. When integrated into a VR headset, the system produces a smell-enhanced environment that significantly increases subjective presence and vividness. This platform provides a compact, low-latency solution for olfactory augmentation in immersive media and human-computer interaction research.

Tinkered soft robots offer significant potential in socially assistive applications; however, their control presents a major barrier for non-expert operators such as therapists and educators. Conventional methods often have a high cognitive load, are non-expressive, or require complex kinematic models that are impractical for customized, handcrafted robots. To address this, we introduce PoseInterp Control, a novel kinematics-free teleoperation approach for tinkered soft robots. This approach allows operators to create a custom control interface by defining a few key robot poses and then fluidly interpolating between them in real-time by moving a single point on a digital canvas. We conducted a within-subject user study (N=6) comparing a 2D implementation of our method with a conventional Direct Actuator Control in a representative greeting task. Our preliminary findings suggest a clear trade-off: while PoseInterp Control required more initial setup time (18.3 vs. 5.8 min), it enabled operators to perform the interactive task more than twice as fast (13.0 vs. 26.5 s). The participants also rated it as significantly more intuitive, less fatiguing, and more enjoyable. PoseInterp Control effectively shifts the cognitive load from real-time operation to a prior setup phase, making it a promising and practical solution for non-experts. This lowers the barrier to creating expressive, interactive behaviors with tinkered soft robots, expanding their potential in socially assistive applications.

This work improves a previously proposed quantification framework by expanding its applicability to quaternary odor mixtures and optimizing the active sensing process. The approach employs four quartz crystal microbalance (QCM) sensors, where both frequency shifts and resistance changes at multiple odd harmonics— measured by vector network analyzers (VNWA)—serve as virtual sensors to enhance selectivity. A selection strategy based on the condition number was introduced to identify informative harmonic responses. Experiments validated that the proposed method reduced the average RMSE by 47.44%, with a statistically significant improvement (p = 0.0070) compared with the only fundamental responses. Among three feedback control algorithms, finite horizon linear–quadratic regulation (LQR) with time-varying gains achieved the best active sensing performance. Experimental evaluations further confirmed short-term and long-term repeatabilities, as well as capability to handle unstable sensor responses. Overall, the proposed method enables accurate and robust quantification of quaternary odor mixtures across a wide recipe range, demonstrating its potential as an easy-to-use solution for future odor recording systems.

This study quantitatively analyzes the structural characteristics of user communities within Social Virtual Reality (Social VR) platforms supporting head-mounted displays (HMDs), based on large-scale log data. By detecting and evaluating community structures from data on substantial interactions (defined as prolonged co-presence in the same virtual space), we found that Social VR platforms tend to host numerous, relatively small communities characterized by strong internal cohesion and limited inter-community connections. This finding contrasts with the large-scale, broadly connected community structures typically observed in conventional Social Networking Services (SNS). Furthermore, we identified a user segment capable of mediating between communities, despite these users not necessarily having numerous direct connections. We term this user segment `community hoppers' and discuss their characteristics. These findings contribute to a deeper understanding of the community structures that emerge within the unique communication environment of Social VR and the roles users play within them.

The presentation of thermal sensation is expected to improve immersive experience. However, thermal perception is slower than visual and tactile perception, and there is insufficient discussion regarding the presentation of the sensation of warmth motion. Conventional methods have explored tactile-dependent illusions; however, these methods are limited in their ability to represent rapid directional changes and fine motions. This study focuses on a pulling illusion, a type of tactile-dependent illusion, and examines whether it can produce the sensation of warmth motion. The experimental results indicate that the pulling illusion creates the sensation of warmth motion. Furthermore, we speculate that the principle underlying this illusion might be the warmth motion in response to changes in the body scheme. Subsequently, we investigated the extent of the warmth motion produced. The results revealed that the subjective motion distance of the illusory warmth motion is considered to be equivalent to the movement of approximately 9.25 mm of a heat source. The findings of this study can serve as a basis for future research into the sensation of warmth motion induced by the pulling illusion and provide design guidelines for warmth motion displays.

This study presents a lightweight, wearable fingertip haptic device that provides physics-based haptic feedback for dexterous manipulation in virtual environments without hindering real-world interactions. The device, designed with thin strings and actuators attached to the fingernails, ensures minimal weight (1.55 g per finger) and preserves finger flexibility. Integrating the software with a physics engine renders multiple types of haptic feedback (grip force, collision, and sliding vibration feedback). We evaluated the device's performance in pressure perception, slip feedback, typical dexterous manipulation tasks, and daily operations, and we gathered user experience through subjective assessments. Our results show that participants could perceive and respond to pressure and vibration feedback. Through dexterous manipulation experiments, we further demonstrated that these minimal haptic cues significantly improved virtual task efficiency, showcasing how lightweight haptic feedback can enhance manipulation performance without complex mechanisms. The device's ability to preserve tactile sensations and minimize hindrance to real-world operations is a key advantage over glove-type haptic devices. This research offers a potential solution for designing haptic interfaces that balance lightweight construction, haptic feedback for dexterous manipulation, and daily wearability.

With a spread of inexpensive and easy-to-use motion tracking methods such as cameras and trackers for virtual realities (VRs), real-time motion-tracked avatars are becoming increasingly common in virtual environments, particularly social VRs, virtual performers (e.g., virtual YouTubers), and VR games. These applications frequently involve interactions among multiple avatars or between avatars and objects for communication or gameplay. However, at present, most applications do not sufficiently consider the effects of contact for avatars, thus leading to penetration or unnatural behavior. To achieve natural avatar motion in such scenarios, the player must perform as if contact has occurred, even though, in reality, there is no contact with the player’s body. While physics simulation can solve the contact issue, the basic use of physics simulation causes tracking delay. We therefore solve this tracking delay problem by employing Featherstone’s algorithm, a reduced-coordinate method for forward dynamics, and by utilizing the Newton-Euler formulation for inverse dynamics to compute tracking forces and torques. To evaluate the delay, we measured the difference between the joint rotations of the simulated model and the input joint rotations. The evaluation with our method indicates the difference is less than 1.4 micro radians for all joints in real time with a small computational cost. Moreover, accurate tracking enables the fixation of both feet. The proposed method provides accurate tracking and soft reactions to contact.