We present a technique to render tactile feedback to the palmar side of the hand while keeping it unobstructed and, thus, preserving manual dexterity during interactions with physical objects. We implement this by applying electro-tactile stimulation only to the back of the hand and to the wrist. In our approach, there are no electrodes on the palmar side, yet that is where tactile sensations are felt. While we place electrodes outside the user’s palm, we do so in strategic locations that conduct the electrical currents to the median/ulnar nerves, causing tactile sensations on the palmar side of the hand. In our user studies, we demonstrated that our approach renders tactile sensations to 11 different locations on the palmar side while keeping users’ palms free for dexterous manipulations. Our approach enables new applications such as tactile notifications during dexterous activities or VR experiences that rely heavily on physical props.
https://doi.org/10.1145/3544548.3581382
Motion effects are indispensable for improving 4D experiences in highly interactive applications, such as amusement parks, 4D theaters, and virtual reality games. Their recent emergence calls for effective algorithms generating motion effects synchronized with audiovisual content. This paper presents an automatic algorithm for synthesizing the object-based motion effects that express the movements of multiple articulated bodies inclusively {\hb when the objects' motion trajectories are available in the 3D camera space.} By taking the visual velocities and sizes of all object parts, our method computes a \textit{motion proxy} that represents the objects' movements by one point and converts the motion proxy to a motion command through a motion cueing algorithm. The motion proxy is determined by linearly combining the velocities, and its best combination was selected from several candidates by user studies. The results of user studies indicate that our algorithm can produce compelling object-based motion effects that enhance the multisensory experience.
https://doi.org/10.1145/3544548.3580727
Vertical force-feedback is extremely rare in mainstream interactive experiences. This happens because existing haptic devices capable of sufficiently strong forces that would modify a user’s jump require grounding (e.g., motion platforms or pulleys) or cumbersome actuators (e.g., large propellers attached or held by the user). To enable interactive experiences to feature jump-based haptics without sacrificing wearability, we propose JumpMod, an untethered backpack that modifies one’s sense of jumping. JumpMod achieves this by moving a weight up/down along the user’s back, which modifies perceived jump momentum—creating accelerated & decelerated jump sensations. In our second study, we empirically found that our device can render five effects: jump higher, land harder/softer, pulled higher/lower. Based on these, we designed four jumping experiences for VR & sports. Finally, in our third study, we found that participants preferred wearing our device in an interactive context, such as one of our jump-based VR applications.
https://doi.org/10.1145/3544548.3580764
Spatiotemporal modulation (STM) is used to render tactile patterns with ultrasound arrays. Previous research only explored the effects of single-point STM parameters, such as drawing speed ($V_d$). Here we explore the effects of multi-point STM on both perceptual (intensity) and emotional (valence/arousal) responses. This introduces a new control parameter for STM - the number of focal points ($N_{fp}$) – on top of conventional STM parameter ($V_d$). Our results from a study with 30 participants showed a negative effect of $N_{fp}$ on perceived intensity and arousal, but no significant effects on valence. We also found the effects of $V_d$ still aligned with prior results for single-point, even when different $N_{fp}$ were used, suggesting that effects observed from single-point also apply to multi-point STM. We finally derive recommendations, such as using single-point STM to produce stimuli with higher intensity and/or arousal, or using multi-point STM for milder and more relaxing (less arousing) experiences.
https://doi.org/10.1145/3544548.3580641
The key assumption attributed to on-body touch input is that the skin being touched provides natural tactile feedback. In this paper, we for the first time systematically explore augmenting on-body touch input with computer-generated tactile feedback. We employ vibrotactile actuation on the fingernail to couple on-body touch input with tactile feedback. Results from our first experiment show that users prefer tactile feedback for on-body touch input. In our second experiment, we determine the frequency thresholds for rendering realistic tactile “click” sensations for on-body touch buttons on three different body locations. Finally, in our third experiment, we dig deeper to render highly expressive tactile effects with a single actuator. Our non-metric multi-dimensional analysis shows that haptic augmentation of on-body buttons enhances the expressivity of on-body touch input. Overall, results from our experiments reinforce the need for tactile feedback for on-body touch input and show that actuation on the fingernail is a promising approach.
https://doi.org/10.1145/3544548.3581473
Using biosignals through electromyography (EMG) and rendering them as feedback for hands-free interaction finally migrates to engaging virtual reality (VR) experiences for health and fitness-related applications. Previous work proposes various body locations as input sources and different output modalities for creating effective biofeedback loops. However, it is currently unknown which muscles and sensory modalities can provide optimal real-time interaction regarding the performance and perceived workload of the users. In two VR studies (N=18 and N=40) based on a Fitts' law target selection task, we explored sensor placement at different body locations and investigate auditory, tactile, and visual feedback modalities. Objective and subjective results indicate that input performance can be improved by presenting muscle tension as simultaneous tactile and visual feedback. We contribute with recommendations for registration of isometric muscle contraction at different body locations and conclude that reproducing physiological feedback through multimodal channels can assist users interacting with EMG devices.
https://doi.org/10.1145/3544548.3580738