Ring interfaces have gained attention in wearable technology for their lightweight and hands-free design. However, their compact form factor limits them to conveying simple information, such as direction or notification, through vibration, electrotactile, or force feedback. In this paper, we introduce HaRing, a novel haptic ring interface equipped with a 4 × 6 pin array display. This dynamic display delivers rich spatial patterns that simple vibration cannot express, effectively conveying high-dimensional information such as directions, semantic symbols, and letters. Its design enables one-handed, eyes-free interaction that does not interfere with visual tasks. We conducted a series of perceptual and user studies to demonstrate its effectiveness, showing a high recognition accuracy of over 94% for complex letters after a brief training period. We anticipate that HaRing can serve as an innovative haptic-only interface for multitasking in real-world or VR environments with high visual load.

Haptic feedback has become a common feature in game experiences, yet little is known about how its effects differ between active players and passive spectators. This study investigated how haptic feedback influences user experience and technology acceptance in the context of first-person shooter (FPS) games, particularly by comparing its effects on active players and passive spectators. An experiment with 60 participants tested four conditions defined by two factors: haptic feedback (present vs. absent) and user role (player vs. spectator). The results showed that haptic feedback enhanced the intention to use games in both roles, with a stronger effect among spectators. Players’ intention was primarily driven by perceived enjoyment through a hedonic pathway, whereas spectators responded to both perceived enjoyment and perceived usefulness through both hedonic and eudaimonic pathways. These findings highlight the need for role-sensitive haptic design and validate two pathways of the Haptic-Augmented Game Technology Acceptance Model (HAG-TAM) for gaming experiences.

This paper presents HaptiCraft, a modular handheld haptic controller designed to replicate the appearance, mass distribution, and multimodal haptic properties of virtual objects. HaptiCraft consists of many modules that provide distinct functions for assembly and multimodal haptic feedback, supporting five types: vibration, impact, thermal, variable inertia, and variable stiffness. Users can readily assemble these modules to create a controller tailored to their needs. To simplify the design process, especially for novice users, we also provide a graphical authoring tool and assess its usability. Finally, we evaluate the system's effectiveness through various virtual reality (VR) scenarios, demonstrating that HaptiCraft significantly enhances user experience. HaptiCraft makes a substantial contribution to the field of VR handheld controllers by offering comprehensive support for shape-changing, variable inertia, and rich multimodal haptic feedback, coupled with an effective authoring method.

In the realm of virtual reality (VR), shape-changing controllers have emerged as a means to enhance visuo-haptic congruence during user interactions. The major emphasis has been placed on manipulating the inertia tensor of a shape-changing controller to control the perceived shape. This paper delves deeper by exploring how the material properties of the controller’s handle, distinct from the inertial information, affect the perceived shape, focusing on the perceived length. We conducted three perceptual experiments to examine the effects of the handle’s softness, thermal conductivity, and texture, respectively. Results demonstrated that a softer handle increases the perceived length, whereas a handle with higher thermal conductivity reduces it. Texture, in the form of varying bumps, also alters the length perception. These results provide more comprehensive knowledge of the intricate relationship between perceived length and controller handle properties, expanding the design alternatives for shape-changing controllers for immersive VR experiences.

We present a visuo-haptic crossmodal model of shape perception designed for shape-changing handheld controllers. The model uses the inertia tensor of an object to bridge the two senses. The model was constructed from the results of three perceptual experiments. In the first two experiments, we validate that the primary moment and product of inertia (MOI and POI) in the inertia tensor have critical effects on the haptic perception of object length and asymmetry. Then, we estimate a haptic-to-visual shape matching model using MOI and POI as two link variables from the results of the third experiment for crossmodal magnitude production. Finally, we validate in a summative user study that the inverse of the shape matching model is effective for pairing a perceptually-congruent haptic object from a virtual object—the functionality we need for shape-changing handheld interfaces to afford perceptually-fulfilling sensory experiences in virtual reality.

One can embed a vibration actuator to a physical button and augment the physical button’s original kinesthetic response with a programmable vibration generated by the actuator. Such vibration-augmented buttons inherit the advantages of both physical and virtual buttons. This paper reports the information transmission capacity of vibration-augmented buttons. It was obtained by conducting a series of absolute identification experiments while increasing the number of augmented buttons. The information transmission capacity found was 2.6 bits, and vibration-augmented and physical buttons showed similar abilities in rendering easily recognizable haptic responses. In addition, we showcase a VR text entry application that utilizes vibration-augmented buttons. Our method provides several error messages to the user during text entry using a VR controller that includes an augmented button. We validate that the variable haptic feedback improves task performance, cognitive workload, and user experience for a transcription task.

As computing paradigms shift toward mobile and ubiquitous interaction, there is an increasing demand for wearable interfaces supporting multifaceted input in smart living environments. In this regard, we introduce a system that identifies contact fingers using vibration as a modality of communication. We investigate the vibration characteristics of the communication channels involved and simulate the transmission of vibration sequences. In the simulation, we test and refine modulation and demodulation methods to design vibratory communication protocols that are robust to environmental noises and can detect multiple simultaneous contact fingers. As a result, we encode an on-off keying sequence with a unique carrier frequency to each finger and demodulate the sequences by applying cross-correlation. We verify the communication protocols in two environments, laboratory and cafe, where the resulting highest accuracy was 93 % and 90.5 %, respectively. Our system achieves over 91 % accuracy in identifying seven contact states from three fingers while wearing only two actuator rings with the aid of a touch screen. Our findings shed light on diversifying touch interactions on rigid surfaces by means of vibratory communication.

In tactile interaction, a phantom sensation refers to an illusion felt on the skin between two distant points at which vibrations are applied. It can improve the perceptual spatial resolution of tactile stimulation with a few tactors. All phantom sensations reported in the literature act on the skin or out of the body, but no such reports exist for those eliciting sensations penetrating the body. This paper addresses tactile phantom sensations in which two vibration actuators on the dorsal and palmar sides of the hand present an illusion of vibration passing through the hand. We also demonstrate similar tactile illusions for the torso. For optimal design, we conducted user studies while varying vibration frequency, envelope function, stimulus duration, and penetrating direction. Based on the results, we present design guidelines on penetrating phantom sensations for its use in immersive virtual reality applications.

Physical buttons provide clear haptic feedback when pressed and released, but their responses are unvarying. Physical buttons can be powered by force actuators to produce unlimited click sensations, but the cost is substantial. An alternative can be augmenting physical buttons with simple and inexpensive vibration actuators. When pushed, an augmented button generates a vibration overlayed on the button's original kinesthetic response, under the general framework of haptic augmented reality. We explore the design space of augmented buttons while changing vibration frequency, amplitude, duration, and envelope. We then visualize the perceptual structure of augmented buttons by estimating a perceptual space for 7 physical buttons and 40 augmented buttons. Their sensations are also assessed against adjectives, and results are mapped into the perceptual space to identify meaningful perceptual dimensions. Our results contribute to understanding the benefits and limitations of programmable vibration-augmented physical buttons with emphasis on their feels.

We present VibEye: a vibration-mediated recognition system of objects for tangible interaction. A user holds an object between two fingers wearing VibEye. VibEye triggers a vibration from one finger, and the vibration that has propagated through the object is sensed at the other finger. This vibration includes information about the object's identity, and we represent it using a spectrogram. Collecting the spectrograms of many objects, we formulate the object recognition problem to a classical classification problem among the images. This simple method, when tested with 20 users, shows 92.5% accuracy for 16 objects of the same shape with various materials. This material-based classifier is also extended to the recognition of everyday objects. Lastly, we demonstrate several tangible applications where VibEye provides the needed functionality while enhancing user experiences. VibEye is particularly effective for recognizing objects made of different materials, which is difficult to distinguish by other means such as light and sound.