Use Of Vibrotactile Feedback Research Articles

Origami-Inspired Vibrotactile Actuator (OriVib): Design and Characterization.

The use of vibrotactile feedback, in place of a full-fledged force feedback experience, has recently received increased attention in haptic communities due to their clear advantages in terms of cost, expressiveness, and wearability. However, designers and engineers are required to trade off a number of technical challenges when designing vibrotactile actuators, including expressiveness (a wide band of actuation frequency), flexibility, and the complexity of the manufacturing process. To address these challenges, we present the design and characterization of an origami-inspired flexible vibrotactile actuator, named OriVib, with a tunable resonance frequency (expressiveness), an origami-inspired design (flexible, soft contact with the human body), and a streamlined manufacturing process (low-cost). Based on its characterization, the fabricated OriVib actuator with 54 mm diameter can produce up to 1.2 g vibration intensity where the vibration intensity increases linearly from 6-11 V input. The resonance frequency is tunable through the characteristic diameter (the resonance frequency decreases in an almost inversely proportional fashion as the diameter increases). As for the thermal signature, the OriVib actuator maintains its temperature below 38 oC when actuated within 6-8 V. In terms of repeatability, the OriVib maintained an average vibration intensity of 0.849 g (standard deviation 0.035 g) for at least 2 million cycles. These results validate the effectiveness of the OriVib actuator to offer an expressive, low-cost, and flexible vibrotactile actuator.

Effect of Vibrations on Impression of Walking and Embodiment With First- and Third-Person Avatar.

We investigate how underfoot vibrotactile feedback can be used to increase the impression of walking and embodiment of static users represented by a first- or third-person avatar. We designed a multi-sensory setup involving avatar displayed on an HMD, and a set of vibrotactile effects displayed at every footstep. In a first study (N = 44), we compared the impression of walking in 3 vibrotactile conditions : 1) with a "constant" vibrotactile rendering reproducing simple contact information, 2) with a more sophisticated "phase-based" vibrotactile rendering the successive contacts of a walking cycle and 3) without vibrotactile feedback. The results show that overall both constant and phase-based rendering significantly improve the impression of walking in first and third-person perspective. Interestingly, the more realistic phase-based rendering seems to increase significantly the impression of walking in the third-person condition, but not in the first-person condition. In a second study (N=28), we evaluated the embodiment towards first- and third-person avatar while receiving no vibrotactile feedback or by receiving vibrotactile feedback. The results show that vibrotactile feedback improves embodiment in both perspectives of the avatar. Taken together, our results support the use of vibrotactile feedback when users observe first- and third-person avatar. They also suggest that constant and phase-based rendering could be used with first-person avatar and support the use of phase-based rendering with third-person avatar. They provide valuable insight for stimulations in any VR applications in which the impression of walking is prominent such as for virtual visits, walking rehabilitation, video games, etc.

VIBES: Vibro-Inertial Bionic Enhancement System in a Prosthetic Socket.

The use of vibrotactile feedback is of growing interest in the field of prosthetics, but few devices fully integrate this technology in the prosthesis to transmit high-frequency contact information (such as surface roughness and first contact) arising from the interaction of the prosthetic device with external items. This study describes a wearable vibrotactile system for high-frequency tactile information embedded in the prosthetic socket. The device consists of two compact planar vibrotactile actuators in direct contact with the user's skin to transmit tactile cues. These stimuli are directly related to the acceleration profiles recorded with two IMUS placed on the distal phalanx of a soft under-actuated robotic prosthesis (Soft-Hand Pro). We characterized the system from a psychophysical point of view with fifteen able-bodied participants by computing participants' Just Noticeable Difference (JND) related to the discrimination of vibrotactile cues delivered on the index finger, which are associated with the exploration of different sandpapers. Moreover, we performed a pilot experiment with one SoftHand Pro prosthesis user by designing a task, i.e. Active Texture Identification, to investigate if our feedback could enhance users' roughness discrimination. Results indicate that the device can effectively convey contact and texture cues, which users can readily detect and distinguish.

Design and Assessment of Digital Musical Devices Yielding Vibrotactile Feedback

Touch has a pivotal importance in determining the expressivity of musical performance for a number of musical instruments. However, most digital musical devices provide no interactive force and/or vibratory feedback to the performer, thus depriving the somatosensory channel of a number of cues. Is the lack of haptic feedback only an aesthetic issue, or does it remove cues essential for digital instrument playing? If so, at which level is the interaction objectively impoverished? What are the effects on musical performance? In this survey article we illustrate our recent research about the use of vibrotactile feedback in three digital instrument interfaces, using tools that we developed over several years and made available to the community in open-source form. These interfaces span a wide range of familiarity and gestural opportunities, enabling us to explore the impact of haptic feedback on different types of digital instruments. We conducted experiments with professional musicians to assess the impact of vibratory cues on both the perceived quality of the instrument and the playing experience, as well as on musical performance. Particular attention was paid to scientific rigor and repeatability of the results, so as to serve as a reference for researchers and practitioners of the musical haptics community. Our results suggest a significant role of vibrotactile feedback in shaping the perception of digital musical instruments, although the effects on musical performance varied depending on the interfaces tested.

Vibrotactile Feedback Improves Foot Placement Perception on Stairs for Lower-Limb Prosthesis Users.

Lower-limb amputees demonstrate decreased performance in stair ambulation compared to their intact-limb counterparts. An estimated 21% of amputees can navigate stairs without a handrail; almost 33% do not use stairs at all. The absence of tactile sensation on the bottom of the foot, creating uncertainty in foot placement, may be overcome by integrating sensory feedback into prosthesis design. Here we describe the design and evaluation of a haptic feedback system worn on the thigh to provide vibrotactile cues of foot placement with respect to stair steps. Tactor discrimination and foot placement awareness tests were performed to analyze system efficacy. Control participants wearing ski boots (N=10) and below-knee amputees (N=2) could discriminate individual tactor vibrations with 95.4% and 90.1% accuracy, respectively. The use of vibrotactile feedback increased accuracy in reporting foot placement by 15% and 17.5%, respectively. These results suggest that using vibrotactile arrays for sensory feedback may improve stair descent performance in lower-limb amputees.

Vibrotactile Feedback During Physical Exercise: Perception of Vibrotactile Cues in Cycling.

The aim of this study was to investigate the perception of vibrotactile signals during physical exercise by comparing differences in recognition between stationary and cycling positions. The impact of physical exercise on the ability to perceive vibrotactile cues is unknown, whereas the recognition in stationary position has been shown previously. Vibrating elements were positioned at 3 locations on the thighs and spine of 9 athletes to apply various vibrotactile cues. Subjects performed at 0, 50, 70 and 90% of their maximal cycling power output and denoted the interpretation of the vibration signals on a touchscreen. The results show a similarity in correct recognition between stationary position and physical exercise for the thighs and spine (p>0.1) and demonstrate a decrease in response time for 70 and 90% levels of physical exercise compared to 0 and 50% (p<0.001). Furthermore, vibrotactile signals at the spine are noticed more accurately and more rapidly compared to the thighs (p<0.01). These results suggest that vibrotactile feedback also has potential in applications during physical exercise. The potential use of vibrotactile feedback can be in cycling for, among other, correcting the aerodynamic position. Applications in other sports and health-related domains are feasible as well.

Transfemoral amputee’s limit of stability and sway analysis during weight shifting exercise with a vibrotactile feedback system

Amputation in the transfemoral amputee (TFA) results in loss of sensory feedback of the amputated limb and therefore results in the poor postural stability. To assess the postural stability, the limit of stability (LOS) is a reliable parameter. In this study, we have investigated the effect of vibrotactile feedback (VF) on the LOS during the weight shifting exercise (WSE) for a TFA. The data of centre of pressure (COP) during WSE was collected from five TFA and five healthy individuals using a zebris force plate. The VF was provided on the amputated/healthy limb’s anterior and posterior part of the stump/thigh during forward and backward WSE, respectively. A customized foot insole with 24 embedded dielectric sensors was used to drive the vibratory motor. The effect of VF was analyzed by pre and post-test. Results show that with the use of VF, TFA significantly improved (t-test, p < .05) the sound limb’s LOS during forward WSE. Also, ANOVA analysis between WSE divisions shows that the prosthetic limb does not follow the path of WSE. We further examine the spectral power using the Welch method to determine the dominant sway frequency of COP. It shows a decreased frequency between 0.5–2 Hz in the healthy and decreased frequency between 0–0.5 Hz and >2 Hz in the amputee with VF. It concluded that VF could improve the LOS of TFA during WSE which ultimately leads to postural stability enhancement.

The Use of Vibrotactile Feedback During Dual-Task Standing Balance Conditions in People With Unilateral Vestibular Hypofunction

People with unilateral vestibular hypofunction (UVH) would have increased postural sway and slower reaction times while using vibrotactile feedback (VTF) during dual-task conditions compared with age-matched controls. VTF has been shown to improve real-time balance performance in persons with vestibular disorders. Future use of this technology outside of the laboratory environment as a real-time balance aid requires that using VTF during dual-tasking scenarios be studied. Nine people with UVH and nine age-matched controls participated in a study focused on assessing the effects of a secondary cognitive task and sensory integration conditions on the root-mean-square of center of pressure (RMS COP) while using VTF. Reaction times from the secondary cognitive task were used to assess the effects of VTF, and sensory integration conditions on the attention required to perform the task. The results showed that there was no group difference between individuals with UVH and age-matched controls on balance performance while using VTF during dual-task conditions. Using VTF significantly degraded the reaction time performance in both groups, and the participants with UVH had slower reaction times compared with controls. People with UVH showed the ability to use VTF to control balance during dual-task conditions, but more attentional resources were needed to perform the secondary cognitive tasks while using VTF.

Vibrotactile Feedback Alters Dynamics Of Static Postural Control In Persons With Parkinson’s Disease But Not Older Adults At High Fall Risk

BackgroundAging and Parkinson’s disease are often associated with impaired postural control. Providing extrinsic feedback via vibrotactile sensation could supplement intrinsic feedback to maintain postural control. Research questionWe investigated the postural control response to vibrotactile feedback provided at the trunk during challenging stance conditions in older adults at high fall risk and individuals with Parkinson’s disease compared to healthy older adults. MethodsNine older adults at high fall risk, 9 persons with Parkinson’s disease and 10 healthy older adults performed 30s quiet standing on a force platform under five challenging stance conditions with eyes open/closed and standing on firm/foam surface with feet together, each with and without vibrotactile feedback. During vibrotactile feedback trials, feedback was provided when participants swayed >10% over the center of their base of support. Participants were instructed vibrations would be in response to their movement. Magnitude of postural sway was estimated using center of pressure path length, velocity, and sway area. Dynamics of individuals’ postural control was evaluated using detrended fluctuation analysis. ResultsResults showed that vibrotactile feedback induced a change in postural control dynamics among persons with Parkinson’s disease when standing with intact intrinsic visual input and altered intrinsic somatosensory input, but there was no change in sway magnitude. However, use of vibrotactile feedback did not significantly alter dynamics of postural control in older adults with high risk of falling or reduce the magnitude of sway. SignificanceConsidering the effects of vibrotactile feedback were dependent on the population and stance condition, designing an optimal therapeutic regimen for balance training should be carefully considered and be specific to a target population. Furthermore, our results suggest that explicit instructions on how to respond to the vibrotactile feedback could affect training outcome.

Gaze Interaction With Vibrotactile Feedback: Review and Design Guidelines

Vibrotactile feedback is widely used in mobile devices because it provides a discreet and private feedback channel. Gaze-based interaction, on the other hand, is useful in various applications due to its unique capability to convey the focus of interest. Gaze input is naturally available as people typically look at things they operate, but feedback from eye movements is primarily visual. Gaze interaction and the use of vibrotactile feedback have been two parallel fields of human–computer interaction research with a limited connection. Our aim was to build this connection by studying the temporal and spatial mechanisms of supporting gaze input with vibrotactile feedback. The results of a series of experiments showed that the temporal distance between a gaze event and vibrotactile feedback should be less than 250 ms to ensure that the input and output are perceived as connected. The effectiveness of vibrotactile feedback was largely independent of the spatial body location of vibrotactile actuators. In comparison to other modalities, vibrotactile feedback performed equally to auditory and visual feedback. Vibrotactile feedback can be especially beneficial when other modalities are unavailable or difficult to perceive. Based on the findings, we present design guidelines for supporting gaze interaction with vibrotactile feedback.

The use of vibrotactile feedback to reduce eating rate

The use of vibrotactile feedback to reduce eating rate

The Use of Vibrotactile Feedback to Restore Texture Recognition Capabilities, and the Effect of Subject Training.

This paper presents a vibrotactile haptic feedback system for use under dynamic conditions, verifies its functionality, and shows how results may be affected by the amount of training that subjects receive. We hope that by using vibrotactile feedback to distinguish between different textures, upper-limb amputees may be able to partially regain the sense of touch. During a previous experiment (Motamedi et al., 2015) we noticed a correlation between how familiar the subjects were with haptic systems, and how well they were able to use the haptic system to accurately identify textures. This observation lead us to conduct a second experiment, the results of which are the main focus of this paper. We began with a group of subjects who were completely unfamiliar with haptic systems, and tracked the improvements in their accuracy over a period of four weeks. Although the subjects showed a 16% improvement in their ability to recognize textures, going from a 64% success rate after the first week to 80% after the fourth, perfect accuracy was not attained. A subsequent experiment, however, shows that this result should not diminish our perception of the haptic system's effectiveness. When we asked the same subjects to identify the textures using only their fingertips, we found that even humans cannot distinguish between near-identical textures with complete accuracy. The subjects' overall success rate when using their own hands was 91%, demonstrating that the proposed haptic system is not far from achieving the same texture recognition capabilities as the human sense of touch.

Assisting people with visual impairments in aiming at a target on a large wall-mounted display

Large interactive displays have become ubiquitous in our everyday lives, but these displays are designed for the needs of sighted people. In this paper, we specifically address assisting people with visual impairments to aim at a target on a large wall-mounted display. We introduce a novel haptic device, which explores the use of vibrotactile feedback in blind user search strategies on a large wall-mounted display. Using mid-air gestures aided by vibrotactile feedback, we compared three target-aiming techniques: Random (baseline) and two novel techniques – Cruciform and Radial. The results of our two experiments show that visually impaired participants can find a target significantly faster with the Cruciform and Radial techniques than with the Random technique. In addition, they can retrieve information on a large display about twice as fast by augmenting speech feedback with haptic feedback in using the Radial technique. Although a large number of studies have been done on assistive interfaces for people who have visual impairments, very few studies have been done on large vertical display applications for them. In a broader sense, this work will be a stepping-stone for further research on interactive large public display technologies for users who are visually impaired.

A smart pressure-sensitive insole that reminds you to walk correctly: an orthotic-less treatment for over pronation.

We equipped an insole with a force sensor that can detect in real time when a foot over pronates. When such behavior is detected, we warn the user so they can correct their posture by using their own muscles. The effectiveness of this novel way to correct over pronation posture is evaluated over a two-week period. The use of vibrotactile feedback reduces over pronation by 30% to 50% during the first week. The natural benefits of the proposed method vs. use of passive orthotics are also presented.

Vibrotactile rendering of splashing fluids.

We introduce the use of vibrotactile feedback as a rendering modality for solid-fluid interaction, based on the physical processes that generate sound during such interactions. This rendering approach enables the perception of vibrotactile feedback from virtual scenarios that resemble the experience of stepping into a water puddle or plunging a hand into a volume of fluid.

Imposing a Networked Vibrotactile Communication System for Improvisational Suggestion

This paper describes the implementation ofNeVIS, a local network system that establishes communication between individual performers, as well as between laptop and performers. Specifically, this is achieved by making use of vibrotactile feedback as a signalling tool within an improvisational setting. A discussion of the current developments regarding the use of networks within improvisation is presented, followed by an outline of the benefits of utilising the haptic feedback channel as a further sensory information pathway when performing digital music. We describe a case study of the system within the context of our computer-mediated improvisational duo Můstek, involving piano, percussion and live electronics. Here, a cueing system or framework is imposed over the improvisation and is transmitted directly to the skin of the performers via tiny vibrations. Additionally, performers may make use of simple vibrotactile signals to enhance traditional visual cues that are often employed within performance. A new work,Socks and Ammo, was created using NeVIS, and was presented at various international conferences and festivals. We also tested the system itself within a group of postgraduate researchers and composers. Qualitative evaluation of the musical outcomes as experienced both by the performers and by the listeners at these events is offered, as well as implications about the nature of collaborative music-making.