IEEE Transactions on Haptics最新文献

The experience of time and space in subjective perception is closely connected. The Kappa effect refers to the phenomenon where the perceived duration of the time interval between stimuli is influenced by the spatial distance between them. In this study, we aimed to explore the Kappa effect from a psychophysical perspective. We investigated participants' perception of temporal duration in the sub-second range by delivering visual and tactile inputs through wearable devices placed on both the palm and the forearm. We compared the impact of unimodal sensory stimulation, involving either visual or tactile stimuli, with different bimodal stimulation conditions. Our results revealed that the illusory effect on inter-stimulus duration perception can be observed in both unimodal conditions, although the distortions were significantly more pronounced in vision. In the multimodal stimulation condition, where visual stimuli were presented at non-equidistant spatial locations, the integration of tactile input did not reduce the Kappa effect, regardless of the spatial location of the tactile stimuli. However, when the visual stimuli were equidistant in space, regardless of the spatial location of the tactile stimuli, the Kappa effect disappeared. These results can shed light on the effect played by multimodality on the perception of space and time.

Wearable vibrotactile devices seem now mature for entering the daily lives and practices of more and more users. However, vibrotactile perception can greatly differ between individuals, in terms of psychophysics and physiology, not to mention higher levels (cognitive or affective for example). Broadly-distributed and affordable vibrotactile devices hence must be adapted to each user's own perception, first of all by delivering intensity levels that are in the perceptible range of the user. This implies determining the user's own thresholds of perception, and then adapting the devices' output levels. Classical methods for the estimation of thresholds elicit too long procedures, and little is known about the reliability of other methods in the vibrotactile domain. This article focuses on two alternative methods for the estimation of amplitude thresholds in the vibrotactile modality ("increasing-intensity" and "decreasing-intensity" methods), and compares their estimations to the estimations from a staircase method. Both rapid methods result in much shorter test durations, and are found less stressful and tiring than the classic method, while showing threshold estimations that are never found to differ by more than 1.5 JND from the estimations by the classic method.

There is a growing interest in using the tactile modality as a compensation or sensory augmentation tool in various fields. The Multichannel Vibrotactile Glove was designed to meet the needs of these diverse disciplines and overcome the limitations of current sound-to-touch technologies. Using 12 independent haptic exciters on each finger's back and on the palm, the device can convey acoustic information to cutaneous vibrotactile receptors with precise control of the location, frequency, timing, and intensity. A staircase method was used to model vibration detection thresholds at six frequencies (100, 200, 250, 500, 800, 1000 Hertz) for each actuator position (All, Thumb, Index, Major, Middle, Pinky, Palm) and both hands (Right, Left). No between hand difference was observed and all finger actuators provided consistent thresholds, except for the Palm which exhibited higher thresholds. Spatial summation effects were observed when all actuators were activated simultaneously. Detection thresholds significantly increased at 100 Hertz and above 500 Hertz. These findings confirm that the system provides uniform stimulation across hands and actuators. Overall, the Multichannel Vibrotactile Glove provides the freedom to send various acoustic features to individual actuators, providing a versatile tool for research and a potential technology to substitute, compensate, or extend sensory perception.

We introduce minimal passive physical realizations of series (damped) elastic actuation (S(D)EA) under closed-loop control to determine the effect of different plant parameters and controller gains on the closed-loop performance of the system and to establish an intuitive understanding of the passivity bounds. Furthermore, we explicitly derive the feasibility conditions for these passive physical equivalents and compare them to the necessary and sufficient conditions for the passivity of S(D)EA under velocity-sourced impedance control (VSIC) to establish their relationship. Through the passive physical equivalents, we rigorously compare the effect of different plant dynamics (e.g., SEA and SDEA) on the system performance. We demonstrate that passive physical equivalents make the effect of controller gains explicit and establish a natural means for effective impedance analysis. We also show that passive physical equivalents promote co-design thinking by enforcing simultaneous and unbiased consideration of (possibly negative) controller gains and plant parameters. We demonstrate the usefulness of negative controller gains when coupled with properly designed plant dynamics. Finally, we provide experimental validations of our theoretical passivity results and comprehensive characterizations of the haptic rendering performance of S(D)EA under VSIC.

Current issues with neuromorphic visual-tactile perception include limited training network representation and inadequate cross-modal fusion. To address these two issues, we proposed a dual network called visual-tactile spiking graph neural network (VT-SGN) that combines graph neural networks and spiking neural networks to jointly utilize the neuromorphic visual and tactile source data. First, the neuromorphic visual-tactile data were expanded spatiotemporally to create a taxel-based tactile graph in the spatial domain, enabling the complete exploitation of the irregular spatial structure properties of tactile information. Subsequently, a method for converting images into graph structures was proposed, allowing the vision to be trained alongside graph neural networks and extracting graph-level features from the vision for fusion with tactile data. Finally, the data were expanded into the time domain using a spiking neural network to train the model and propagate it backwards. This framework effectively utilizes the structural differences between sample instances in the spatial dimension to improve the representational power of spiking neurons, while preserving the biodynamic mechanism of the spiking neural network. Additionally, it effectively solves the morphological variance between the two perceptions and further uses complementary data between visual and tactile. To demonstrate that our approach can improve the learning of neuromorphic perceptual information, we conducted comprehensive comparative experiments on three datasets to validate the benefits of the proposed VT-SGN framework by comparing it with state-of-the-art studies.

Numerous studies have indicated that the use of a closed-loop haptic feedback system, which offers various mechano-tactile stimuli patterns with different actuation methods, can improve the performance and grasp control of prosthetic hands. Purely mechanical-driven feedback approaches for various mechano-tactile stimuli patterns, however, have not been explored. In this paper, a multi-cavity fluidic haptic feedback system is introduced with details of design, fabrication, and validation. The multi-cavity haptic feedback system can detect the physical touch with direction at the fingertip sensor. The direction of the force is reflected in the form of pressure deviation in the multi-cavity fingertip sensor. The feedback actuator generates various mechano-tactile stimuli patterns according to the pressure deviation from the fingertip sensor. Hence, users can identify the force with direction according to the stimuli patterns. The haptic feedback system is validated through two experiments. The initial experiment characterises the system and establishes the relationship between the fingertip sensor and feedback actuator. The subsequent experiment, a human interaction test, confirms the system's capability to detect force with directions and generate corresponding tactile stimuli in the feedback actuator. The outcomes corroborate the idea that participants are generally capable of discerning changes in angle.

Haptic rendering of weight plays an essential role in naturalistic object interaction in virtual environments. While kinesthetic devices have traditionally been used for this aim by applying forces on the limbs, tactile interfaces acting on the skin have recently offered potential solutions to enhance or substitute kinesthetic ones. Here, we aim to provide an in-depth overview and comparison of existing tactile weight rendering approaches. We categorized these approaches based on their type of stimulation into asymmetric vibration and skin stretch, further divided according to the working mechanism of the devices. Then, we compared these approaches using various criteria, including physical, mechanical, and perceptual characteristics of the reported devices. We found that asymmetric vibration devices have the smallest form factor, while skin stretch devices relying on the motion of flat surfaces, belts, or tactors present numerous mechanical and perceptual advantages for scenarios requiring more accurate weight rendering. Finally, we discussed the selection of the proposed categorization of devices together with the limitations and opportunities for future research. We hope this study guides the development and use of tactile interfaces to achieve a more naturalistic object interaction and manipulation in virtual environments.

In cutaneous displays in which both tactile and thermal signals are presented, it is important to understand the temporal requirements associated with presenting these signals so that they are perceptually synchronous. Such synchrony is important to provide realistic touch experiences in applications involving object recognition and social touch interactions. In the present experiment the temporal window within which tactile and warm thermal stimuli are perceived to occur at the same time was determined. A Simultaneity Judgment Task was used in which pairs of tactile and thermal stimuli were presented on the hand at varying stimulus onset asynchronies, and participants determined whether the stimuli were simultaneous or not. The results indicated that the average simultaneity window width was 1041 ms. The average point of subjective simultaneity (PSS) was -569 ms, indicating that participants perceived simultaneity best when the warm thermal stimulus preceded the tactile stimulus by 569 ms. These findings indicate that thermal and tactile stimuli do not need to be displayed simultaneously for the two stimuli to be perceived as being synchronous and therefore the timing of such stimuli can be adjusted to maximize the likelihood that they will both be perceived.

We investigate the effect of finger moisture on the tactile perception of electroadhesion with 10 participants. Participants with moist fingers exhibited markedly higher threshold levels. Our electrical impedance measurements show a substantial reduction in impedance magnitude when sweat is present at the finger-touchscreen interface, indicating increased conductivity. Supporting this, our mechanical friction measurements show that the relative increase in electrostatic force due to electroadhesion is lower for a moist finger.

Humans rely on multimodal perception to form representations of the world. This implies that environmental stimuli must remain consistent and predictable throughout their journey to our sensory organs. When it comes to vision, electromagnetic waves are minimally affected when passing through air or glass treated for chromatic aberrations. Similar conclusions can be drawn for hearing and acoustic waves. However, tools that propagate elastic waves to our cutaneous afferents tend to color tactual perception due to parasitic mechanical attributes such as resonances and inertia. These issues are often overlooked, despite their critical importance for haptic devices that aim to faithfully render or record tactile interactions. Here, we investigate how to optimize this mechanical transmission with sandwich structures made from rigid, lightweight carbon fiber sheets arranged around a 3D-printed lattice core. Through a comprehensive parametric evaluation, we demonstrate how this design paradigm provides superior haptic transparency, regardless of the lattice types. Drawing an analogy with topology optimization, our solution approaches a foreseeable technological limit. It offers a practical way to create high-fidelity haptic interfaces, opening new avenues for research on tool-mediated interactions.