Evaluating vibrotactile dimensions for the design of tactons

Exploring Bimanual Haptic Feedback for Spatial Search in Virtual Reality

Spatial search tasks are common and crucial in many Virtual Reality (VR) applications. Traditional methods to enhance the performance of spatial search often employ sensory cues such as visual, auditory, or haptic feedback. However, the design and use of bimanual haptic feedback with two VR controllers for spatial search in VR remains largely unexplored. In this work, we explored bimanual haptic feedback with various combinations of haptic properties, where four types of bimanual haptic feedback were designed, for spatial search tasks in VR. Two experiments were designed to evaluate the effectiveness of bimanual haptic feedback on spatial direction guidance and search in VR. The results from the first experiment reveal that our proposed bimanual haptic schemes significantly enhanced the recognition of spatial directions in terms of accuracy and speed compared to spatial audio feedback. The second experiment's findings suggest that the performance of bimanual haptic feedback was comparable to or even better than the visual arrow, especially in reducing the angle of head movement and enhancing searching targets behind the participants, which was supported by subjective feedback as well. Based on these findings, we have derived a set of design recommendations for spatial search using bimanual haptic feedback in VR.

A Perceptual Model-Based Approach to Plausible Authoring of Vibration for the Haptic Metaverse

Haptic virtual reality is often misunderstood as being solely a physically identical copy of real environments. Thus, a perfect recording and reproduction of vibration that is indistinguishable in an A:B comparison is often the aim. However, in most virtual reality applications the real environment is not available for direct comparison. Instead, when judging the plausibility of a presented scene, the user compares the vibration to his expectations shaped by the audiovisual context. Therefore, it should be sufficient to find any vibration that the user expects to potentially occur in the given context. Such a vibration needs to elicit a perceptual profile with a minimal distance to an expected profile in the sensory tactile perceptual space. Building onto this formalization, this article demonstrates a novel generative model-based approach to authoring vibrations. First, users quantify expectations as tactile profiles consisting of ratings of six sensory tactile attributes without the presence of vibrations. Subsequently, the model predicts vibration parameters from such profiles. This ensures the fulfillment of user expectations and thus high plausibility. Furthermore, it eliminates the necessity of recordings, infeasible for scenes with no real counterpart and opens the door to crowdsourcing the authoring process with laypersons for the haptic metaverse.

A Wearable Textile-Embedded Dielectric Elastomer Actuator Haptic Display

With advances in mobile computing and virtual/augmented reality technologies, communicating through touch using wearable haptic devices is poised to enrich and augment current information delivery channels that typically rely on sight and hearing. To realize a wearable haptic device capable of effective data communication, both ergonomics and haptic performance (i.e., array size, bandwidth, and perception accuracy) are essential considerations. However, these goals often involve challenging and conflicting requirements. We present an integrated approach to address these conflicts, which includes incorporating multilayered dielectric elastomer actuators, a lumped-parameter model of the skin, and a wearable frame in the design loop. An antagonistic arrangement-consisting of an actuator deforming the skin-was used to achieve effective force transmission while maintaining a low profile, and the effect of the wearable frame and structure was investigated through lumped-model analysis and human perception studies.

The Effects of Vibratory Frequency and Temporal Interval on Tactile Apparent Motion

Vibrotactile stimuli can be used to generate the haptic sensation of a static object or the motion of a dynamic object. Here, in this article, we investigated the effects of vibratory frequency and temporal interval on tactile apparent motion. In the experiment, we examined the effect of vibratory frequency with different temporal intervals on tactile apparent motion that results from two successive tactile stimuli on the index fingerpad. Results indicated that tactile apparent motion was perceived not only when both stimuli were either "flutter" or "vibration" stimuli, but also when one of each type was used. Specifically, when the first stimulus was introduced at 40Hz, "continuous motion" was viewed at all combinations of stimulus frequency, and "continuous motion" was clearly noted at the high-frequency combination instead of the low-frequency combination. Also, tactile apparent motion was predominantly viewed in the SOA range of 105 ms to 125 ms. We anticipate that our findings and further research will be essential resources for the design of tactile devices to represent the motion of dynamic objects.

Mapping the Sensory-Perceptual Space of Vibration for User-Centered Intuitive Tactile Design

In vibrotactile design, it can be beneficial to communicate with potential users about the desired properties of a product. However, such users' expectations would need to be translated into physical vibration parameters. In everyday life, humans are frequently exposed to seat vibration. Humans have learned to intuitively associate specific labels (e.g., "tingling") with specific vibrations. Thus, the aim of this article is to identify the most common sensory-perceptual attributes and their relationships to vibration parameters. First, we generalized everyday-life seat vibration into sinusoidal, amplitude-modulated sinusoidal, white Gaussian noise and impulse-like vibrations. Subsequently, the (peak) level, (center/carrier) frequency, bandwidth, modulation frequency and exponential decay rate parameters of these vibrations were systematically varied depending on the signal type. A free association task was conducted to reveal the most common sensory-perceptual attributes for each vibration. After aggregating similar attributes, the 21 most frequently occurring attributes were utilized in a second experiment to rate their suitability for describing each vibration stimulus. Principal component analysis guided the selection of six attribute groups, which can be represented by "up and down," "tingling," "weak," "repetitive," "uniform" and "fading." The observed relationships between vibration parameters and attribute ratings are suitable for future model building.

Improvements in the learnability of smartphone haptic interfaces for visually impaired users

We report the results of a study on the learnability of haptic icons used as alerts or notifications in smartphones. The aim was to explore the feasibility of using haptic icons to create assistive technologies for people with visual impairments. We compared the performance and satisfaction of users with different visual capacities (visually impaired vs. sighted) and using different learning processes (with or without a reinforcement learning stage). The reinforcement learning stage improves the recognition rate in both types of users, although the improvement obtained by the visually impaired users is even better as their recognition rates become very similar to those obtained by the sighted users. Finally, it was observed that the better recognized haptic icons are those assigned to the most employed applications by the user.