Anticipatory Vibrotactile Cueing Facilitates Grip Force Adjustment during Perturbative Loading

Grip force applied to an object held between the thumb and index finger is automatically and unconsciously adjusted upon perception of an external disturbance to the object. Typically, this adjustment occurs within approximately 100 ms. Here, we investigated the effect of anticipatory vibrotactile cues prior to a perturbative force, which the central nervous system may use for rapid grip re-stabilization. We asked participants to grip and hold an instrumented, actuated handle between the thumb and index finger. Under computer control, the handle could suddenly be pulled away from a static grip and could independently provide vibration to the gripping fingers. The mean latency of corrective motor action was 139 ms. When vibrotactile stimulation was applied 50 ms before application of tractive force, the latency was reduced to 117 ms, whereas the mean latency of the conscious response to vibrotactile stimuli alone was 229 ms. This suggests that vibrotactile stimulation can influence reflex-like actions. We also examined the effects of anticipatory cues using a set of perturbative loads with different rising rates. As expected, facilitation of grip force adjustment was observed for moderate loads. In contrast, anticipatory cues had an insignificant effect on rapid loads that evoked an adjustment within 60-80 ms, which approaches the minimum latency of human grip adjustment. Understanding the facilitative effects of anticipatory cues on human reactive grip can aid the development of human-machine interfaces to enhance human behavior

Travelling Ultrasonic Wave Enhances Keyclick Sensation

International audienceA realistic keyclick sensation is a serious challenge for haptic feedback since vibrotactile rendering faces the limitation of the absence of contact force as experienced on physical buttons. It has been shown that creating a keyclick sensation is possible with stepwise ultrasonic friction modulation. However, the intensity of the sensation is limited by the impedance of the fingertip and by the absence of a lateral force component external to the finger. In our study, we compare this technique to rendering with an ultrasonic travelling wave, which exerts a lateral force on the fingertip. For both techniques, participants were asked to report the detection (or not) of a keyclick during a forced choice one interval procedure. In experiment 1, participants could press the surface as many time as they wanted for a given trial. In experiment 2, they were constrained to press only once. The results show a lower perceptual threshold for travelling waves. Moreover, participants pressed less times per trial and exerted smaller normal force on the surface. The subjective quality of the sensation was found similar for both techniques. In general, haptic feedback based on travelling ultrasonic waves is promising for applications without lateral motion of the finger

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon

ViPong: Probabilistic haptic feedback for eyes-free interaction

Conference of 2013 IEEE World Haptics Conference, WHC 2013 ; Conference Date: 14 April 2013 Through 17 April 2013; Conference Code:98366International audienceWe describe a mechanism for the delivery of haptic feedback to users of a simple game via the use of probabilistic inference. This not only enables the creation of dynamically changing game conditions but also a more adaptable, accessible and enjoyable haptic gaming environment for potential use by visually impaired users. The ViPong proof of concept application uses a mouse instrumented with a custom built lateral vibrator to enable a person to compete eyes-free in a game of pong using only haptic feedback linked to the position of the ball. A preliminary user study shows that it is possible to build eyes-free games using such a mechanism for haptic feedback generation. It also shows that there is some effect on the game play from varying levels of uncertainty injected into the algorithm, with participants performing less well under condition where the uncertainty added to the position of the game ball is high

A High-Fidelity Surface-Haptic Device for Texture Rendering on Bare Finger

We present the design and evaluation of a high fidelity surfacehaptic device. The user slides a finger along a glass plate while friction is controlled via the amplitude modulation of ultrasonic vibrations of the plate. A non-contact finger position sensor and low latency rendering scheme allow for the reproduction of fine textures directly on the bare finger. The device can reproduce features as small as 25 μm while maintaining an update rate of 5 kHz. Signal attenuation, inherent to resonant devices, is compensated with a feedforward filter, enabling an artifact-free rendering of virtual textures on a glass plate

Overcoming the Variability of Fingertip Friction with Surface-Haptic Force-Feedback

International audienceTouch screens have pervaded our lives as the most widely used human-machine interface, and much research has focused recently on producing vivid tactile sensations on these flat panels. One of the main methods used for this purpose is based on ultrasonic vibration to controllably reduce the friction experienced by a finger touching a glass plate. Typically, these devices modulate the amplitude of the vibration in order to control the frictional force that the finger experiences without monitoring the actual output. However, since friction is a complex physical process, the open-loop transfer function is not stationary and varies with a wide range of external parameters such as the velocity of exploration or the ambient moisture. The novel interface we present here incorporates a force sensor which measures subtle changes of the frictional force on a wide frequency bandwidth including static forces. This force sensor is the basis for real time control of the frictional force of the finger, which reduces significantly the inherent variability of ultrasonic friction modulation while maintaining a noise level below human perception thresholds. The interface is able to render of precise and sharp frictional patterns directly on the user's fingertip

Assessing the cumulative effects of disease-modifying therapies on the current risk of irreversible disability in patients with relapsing-remitting multiple sclerosis

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Developing tools to evaluate quality of care management for patients living with multiple sclerosis: An original French initiative

International audienceINTRODUCTION: Assessing the quality of care management for patients with a chronic disease such as multiple sclerosis (MS) is a major challenge for healthcare systems around the world. It needs to be carried out using tools that are recognized by professionals and patients alike, and should concern practices, systems, and scientific data. No such tools are currently available in Europe. The purpose of the present study was to develop indicators to contribute to assess the quality of care management for patients with MS in France. METHODS: An expert panel comprising 25 professionals from well known teams across France selected the indicators on the basis of consensus. In accordance with the Rand/UCLA Appropriateness Method, each expert had to agree with the recommendations, and there had to be agreement among the experts. RESULTS: The expert panel selected 48 indicators representing seven domains of care management for patients with MS: physical and rehabilitation medicine, disease progression, access to care, magnetic resonance imaging (MRI) management, relapse management, management of disease-modifying treatments, and management of the symptoms of disability progression. Some of these quality indicators (notably pertaining to MRI management) had not previously been identified in the literature. CONCLUSION: These indicators may allow professionals to comprehensively assess and compare their practices and cooperation, thereby contributing to improve the quality of care management for patients with MS in France

Discontinuation of high- versus middle-efficacy disease-modifying treatment in middle-aged patients with multiple sclerosis

International audienceMeeting Abstract EP116338th Congress of the European-Committee-for-Treatment-and-Research-in-Multiple-SclerosisAmsterdam, NETHERLANDSOCT 26-28, 202