Experimental evaluation of vibrotactile training mappings for dual-joystick directional guidance

Two joystick-based teleoperation is a common method for controlling a remote machine or a robot. Their use could be counter-intuitive and could require a heavy mental workload. The goal of this paper is to investigate whether vibrotactile prompts could be used to trigger dual-joystick responses quickly and intuitively, so to possibly employ them for training. In particular, we investigate the effects of: (1) stimuli delivered either on the palm or on the back of the hand, (2) with attractive and repulsive mappings, (3) with single and sequential stimuli. We find that 38 participants responded quicker and more accurately when stimuli were delivered on the back of the hand, preferred to move towards the vibration. Sequential stimuli led to intermediate responses in terms of speed and accuracy

An Exploration of Just Noticeable Differences in Mid-Air Haptics

Mid-air haptic feedback technology produces tactile sensations that are felt without the need for physical interactions, wearables or controllers. When designing mid-air haptic stimuli, it is important that they are sufficiently different in terms of their perceived sensation.This paper presents the results of two user studies on mid-air haptic feedback technology, with a focus on the sensations of haptic strength and haptic roughness. More specifically, we used the acoustic pressure intensity and the rotation frequency of the mid-air haptic stimulus as proxies to the two sensations of interest and investigated their Just Noticeable Difference (JND) and Weber fractions. Our results indicate statistical significance in the JND for frequency, with a finer resolution compared to intensity. Moreover, correlations are observed in terms of participants' sensitivity to small changes across the different stimuli presented. We conclude that frequency and intensity are mid-air haptic dimensions of depth 5 and 3, respectively, that we can use for the design of distinct stimuli that convey perceptually different tactile information to the user

Tactile Roughness Perception of Virtual Gratings by Electrovibration

Realistic display of tactile textures on touch screens is a big step forward for haptic technology to reach a wide range of consumers utilizing electronic devices on a daily basis. Since the texture topography cannot be rendered explicitly by electrovibration on touch screens, it is important to understand how we perceive the virtual textures displayed by friction modulation via electrovibration. We investigated the roughness perception of real gratings made of plexiglass and virtual gratings displayed by electrovibration through a touch screen for comparison. In particular, we conducted two psychophysical experiments with 10 participants to investigate the effect of spatial period and the normal force applied by finger on roughness perception of real and virtual gratings in macro size. We also recorded the contact forces acting on the participants' finger during the experiments. The results showed that the roughness perception of real and virtual gratings are different. We argue that this difference can be explained by the amount of fingerpad penetration into the gratings. For real gratings, penetration increased tangential forces acting on the finger, whereas for virtual ones where skin penetration is absent, tangential forces decreased with spatial period. Supporting our claim, we also found that increasing normal force increases the perceived roughness of real gratings while it causes an opposite effect for the virtual gratings. These results are consistent with the tangential force profiles recorded for both real and virtual gratings. In particular, the rate of change in tangential force ($dF_t/dt$) as a function of spatial period and normal force followed trends similar to those obtained for the roughness estimates of real and virtual gratings, suggesting that it is a better indicator of the perceived roughness than the tangential force magnitude.Comment: Manuscript received June 25, 2019; revised November 15, 2019; accepted December 11, 201

The high/low frequency balance drives the perception of noisy vibrations

Noisy vibrotactile signals transmitted during tactile explorations of an object provide precious information on the nature of its surface. Linking the properties of such vibrotactile signals to the way they are interpreted by the haptic sensory system remains challenging. In this study, we investigated humans' perception of noisy, stationary vibrations recorded during exploration of textures and reproduced using a vibrotactile actuator. Since intensity is a well-established essential perceptual attribute, an intensity equalization was first conducted, providing a model for its estimation. The equalized stimuli were further used to identify the most salient spectral features in a second experiment using dissimilarity estimations between pairs of vibrations. Based on dimensionally reduced spectral representations, linear models of dissimilarity prediction showed that the balance between low and high frequencies was the most important cue. Formal validation of this result was achieved through a Mushra experiment, where participants assessed the fidelity of resynthesized vibrations with various distorted frequency balances. These findings offer valuable insights into human vibrotactile perception and establish a computational framework for analyzing vibrations as humans do. Moreover, they pave the way for signal synthesis and compression based on sparse representations, holding significance for applications involving complex vibratory feedback

Haptics: Science, Technology, and Applications, 11th International Conference, EuroHaptics 2018, Pisa, Italy, June 13-16, 2018, Proceedings, Part II

The proceedings contain 36 papers. The special focus in this conference is on Science, Technology, and Applications. The topics include: Identification and evaluation of perceptual attributes for periodic whole-body and hand-arm vibration; influence of shape elements on performance during haptic rotation; effects of Chai3D texture rendering parameters on texture perception; effect of control movement scale on visual haptic interactions; tactile apparent motion through human-human physical touch; preliminary stiffness perception assessment for a tele-palpation haptic interface; passive probing perception: Effect of latency in visual-haptic feedback; perceived frequency of aperiodic vibrotactile stimuli depends on temporal encoding; haptic tracing of midair linear trajectories presented by ultrasound bessel beams; is cross-modal matching necessary? A bayesian analysis of individual reference cues; asymmetric cooling and heating perception; haptic scene analysis: Mechanical property separation despite parasitic dynamics; influence of scanning velocity on skin vibration for coarse texture; judged roughness as a function of groove frequency and groove width in 3D-printed gratings; using spatiotemporal modulation to draw tactile patterns in mid-air; discovering articulations by touch: A human study for robotics applications; a multimodal illusion of force improves control perception in above-surface gesture: Elastic zed-zoom; pseudohaptic feedback for teleoperated gripping interactions; a pilot study: Introduction of time-domain segment to intensity-based perception model of high-frequency vibration; haptic human-human interaction through a compliant connection does not improve motor learning in a force field; differences in beta oscillation of the middle frontal cortex with or without tactile stimulation in active touch task; relative sensation of wetness of different materials

Haptics: Science, Technology, and Applications, 11th International Conference, EuroHaptics 2018, Pisa, Italy, June 13-16, 2018, Proceedings, Part I

The proceedings contain 36 papers. The special focus in this conference is on Science, Technology, and Applications. The topics include: Identification and evaluation of perceptual attributes for periodic whole-body and hand-arm vibration; influence of shape elements on performance during haptic rotation; effects of Chai3D texture rendering parameters on texture perception; effect of control movement scale on visual haptic interactions; tactile apparent motion through human-human physical touch; preliminary stiffness perception assessment for a tele-palpation haptic interface; passive probing perception: Effect of latency in visual-haptic feedback; perceived frequency of aperiodic vibrotactile stimuli depends on temporal encoding; haptic tracing of midair linear trajectories presented by ultrasound bessel beams; is cross-modal matching necessary? A bayesian analysis of individual reference cues; asymmetric cooling and heating perception; haptic scene analysis: Mechanical property separation despite parasitic dynamics; influence of scanning velocity on skin vibration for coarse texture; judged roughness as a function of groove frequency and groove width in 3D-printed gratings; using spatiotemporal modulation to draw tactile patterns in mid-air; discovering articulations by touch: A human study for robotics applications; a multimodal illusion of force improves control perception in above-surface gesture: Elastic zed-zoom; pseudohaptic feedback for teleoperated gripping interactions; a pilot study: Introduction of time-domain segment to intensity-based perception model of high-frequency vibration; haptic human-human interaction through a compliant connection does not improve motor learning in a force field; differences in beta oscillation of the middle frontal cortex with or without tactile stimulation in active touch task; relative sensation of wetness of different materials