Pseudo-Weight: Making Tabletop Interaction with Virtual Objects More Tangible

International audienceIn this paper we show that virtual objects manipulated on a tabletop interaction device can be augmented to provide the illusion they have a weight. This weight offers a supplemental channel to provide information about graphical objects without cluttering the visual display. To create such a pseudo-weight illusion on a passive device, the pressure applied with the fingers during the interaction has to be captured. We show that this pressure can be estimated without hardware modification on some touch sensitive tabletop setups (e.g., MERL's DiamondTouch). Two controlled experiments show that pseudo-weight is perceived effectively. The first one demonstrates that users, without training and without previous knowledge of the system, can accurately rank virtual objects according to their pseudo-weights, provided they are sufficiently distinct. The second controlled experiment investigates more formally the relation between the pseudo-weight and the actual perception of the users

Short paper : Role of force-cues in path following of 3D trajectories in Virtual Reality.

International audienceThis paper examines the effect of adding haptic force cues (simulated inertia, compensation of gravity) during 3D-path following in large immersive virtual reality environments. Thirty-four participants were asked to follow a 3D ring-on-wire trajectory. The experiment consisted of one pre-test/control bloc of twelve trials with no haptic feedback; followed by three randomized blocs of twelve trials, where force feedbacks differed. Two levels of inertia were proposed and one level compensating the effect of gravity (No-gravity). In all blocks, participants received a real time visual warning feedback (color change), related to their spatial performance. Contrariwise to several psychophysics studies, haptic force cues did not significantly change the task performance in terms of time completion or spatial distance error. The participants however significantly reduced the time passed in the visual warning zone in the presence of haptic cues. Taken together, these results are discussed from a psychophysics and multi-sensory integration point of view

L'estimation kinesthésique des distances : études comportementales et analyse probabiliste

National audienceThe purpose of the present paper is to review studies examining the estimation of distances on the basis of kinesthetic cues. In this kind of task, blindfolded participant explores a path (target distance) with one arm-hand system and reproduces later its distance with the same arm-hand system. The analysis of data shows the estimations depend on three types of factor : 1) the geometrical cues ; 2) the force cues ; and 3) the cognitive factors. Moreover, the analysis about the different variables used by researchers to measure the performance shows that the different types of errors - constant, absolute and variable errors- have been processed either conjointly or independently. By casting these error measures in the probabilistic modeling framework, we show that none of these is inherently more adequate than the others; they differ in the underlying, implicit hypotheses they assume. Discussing the relevance of these error measures thus amounts to discussing the validity of these hypotheses, which fortunately, could be assessed experimentally.Cette revue critique concerne les processus psychologiques par lesquels nous estimons des distances en utilisant les indices kinesthésiques en l'absence d'informations visuelles. Le paradigme expérimental utilisé par les chercheurs consiste à demander à des sujets (sous occlusion visuelle momentanée) d'explorer avec le système bras-main une distance cible et puis de la reproduire avec la même main. L'analyse des données de la littérature scientifique montre que l'estimation kinesthésique des distances dépend de trois types de facteurs : 1) les indices géométriques, 2) les indices de force et 3) les facteurs cognitifs. De plus, l'analyse des mesures utilisées par les chercheurs pour quantifier cette estimation révèle que les différents types de mesure -l'erreur constante, l'erreur variable et l'erreur absolue- sont traités soit conjointement soit indépendamment. En replaçant ces mesures dans le cadre d'une analyse probabiliste, il apparaît qu'aucune de ces dernières n'est intrinsèquement meilleure que les autres. En réalité, elles font des hypothèses implicites différentes. Discuter de la pertinence de ces mesures d'erreurs revient donc à discuter de la validité de ces hypothèses sous-jacentes, ce qui, heureusement, peut être examiné expérimentalement

Haptic guidance improves the visuo-manual tracking of trajectories

BACKGROUND: Learning to perform new movements is usually achieved by following visual demonstrations. Haptic guidance by a force feedback device is a recent and original technology which provides additional proprioceptive cues during visuo-motor learning tasks. The effects of two types of haptic guidances-control in position (HGP) or in force (HGF)-on visuo-manual tracking ("following") of trajectories are still under debate. METHODOLOGY/PRINCIPALS FINDINGS: Three training techniques of haptic guidance (HGP, HGF or control condition, NHG, without haptic guidance) were evaluated in two experiments. Movements produced by adults were assessed in terms of shapes (dynamic time warping) and kinematics criteria (number of velocity peaks and mean velocity) before and after the training sessions. CONCLUSION/SIGNIFICANCE: These results show that the addition of haptic information, probably encoded in force coordinates, play a crucial role on the visuo-manual tracking of new trajectories

Evaluation des effets de l'ajout d'interfaces haptiques sur le suivi manuel de trajectoires

Les interfaces haptiques sont des dispositifs relativement récents issus du monde de la robotique et de l'informatique, qui permettent de générer des retours sensoriels à destination de l'utilisateur. Or, il est difficile à l'heure actuelle d'identifier avec précision les influences de ces retours sensoriels sur la réalisation de tâches dans lesquelles ils se trouvent appliqués. Par exemple, pouvons nous utiliser ces dispositifs en vue de fournir une aide (ou un guidage) au geste réalisé ? Le fait d'ajouter des informations tactiles modifie-t-il notre perception de la tâche ? Comment le geste d'un chirurgien sera-t-il modifié en présence d'un dispositif haptique dans un simulateur de chirurgie ? Afin d'apporter des éléments de réponse à ces multiples interrogations, nous avons étudié les effets de l'ajout d'interfaces haptiques ou/et tactiles sur le suivi manuel de trajectoires bidimensionnelles ou tridimensionnelles au mode visuel classique de retour d'informations. Ce travail se situe à la frontière de plusieurs disciplines impliquant la compréhension des mécanismes cognitifs de traitement des informations somesthésique multi sensorielles (psychologie cognitive), l'étude du fonctionnement de ces dispositifs et donc la manière dont les informations numériques sont calculées (informatique et robotique) et la mise en œuvre de ces appareils dans une contexte de simulation (réalité virtuelle). Suite à une première partie bibliographique sur les caractéristiques du toucher, les dispositifs haptique et la problématique de guidage haptique, de nombreuses questions relatives à l'analyse de la performance humaine subsistent. Nos premières contributions quant au choix de méthodes d'analyses et des indices liés à la mesure de la performance du geste manuel sont exposées dans la seconde partie de ce rapport. L'étude proprement dite de l'influence des dispositifs haptique a été conduite dans la troisième partie de ce manuscrit, à travers une série d'expérimentations impliquant des trajectoires bidimensionnelles (geste d'écriture) ou tridimensionnelles (en réalité virtuelle ou dans l'utilisation au sein d'un simulateur de chirurgie), différents types de dispositifs haptiques (vibrotactiles ou à retour d'effort) et de multiples tâches (écriture, manipulation dans une configuration de réalité virtuelle ou encore chirurgie de la base du crâne). Ces expérimentations nous ont permis d'apporter une meilleure compréhension des implications des dispositifs haptiques sur le geste manuel en terme de modification des indices haptiques présents et de guidage haptique. La dernière partie de ce rapport intègre nos résultats de recherches dans une discussion transversale, apportant des tentatives de réponses à la problématique du sujet et un certain nombre de perspectives.to come soon..

Haptic guidances increase the visuomanual tracking of Japanese and Arabic letters

Haptic guidance by a force feedback device is a technology which provides additional proprioceptive cues during visuo-motor learning tasks. The effects of two types of haptic guidance - control in position (HGP) or in force (HGF) – on visuo-manual tracking (“following”) of trajectories are still under debate. Three training techniques of haptic guidance (HGP, HGF or NHG control condition without haptic guidance) were evaluated. Movements produced by adults were assessed in terms of shapes (dynamic time warping) and kinematics criteria (number of velocity peaks and mean velocity) before and after the training sessions. Trajectories consisted of two Arabic and two Japanese-inspired letters. Results revealed both types of haptic guidance do not influence the shape quality, mainly guided by visual feedbacks. Moreover, the use of HGF globally improves the fluidity of the four movements while no significant improvement was found for HGP or NHG.. These results suggest that learned information for this specific motor activity could be stored as internal inverse model andencoded in force coordinates

Haptic guidances increase the visuomanual tracking of Japanese and Arabic letters

Haptic guidance by a force feedback device is a technology which provides additional proprioceptive cues during visuo-motor learning tasks. The effects of two types of haptic guidance - control in position (HGP) or in force (HGF) – on visuo-manual tracking (“following”) of trajectories are still under debate. Three training techniques of haptic guidance (HGP, HGF or NHG control condition without haptic guidance) were evaluated. Movements produced by adults were assessed in terms of shapes (dynamic time warping) and kinematics criteria (number of velocity peaks and mean velocity) before and after the training sessions. Trajectories consisted of two Arabic and two Japanese-inspired letters. Results revealed both types of haptic guidance do not influence the shape quality, mainly guided by visual feedbacks. Moreover, the use of HGF globally improves the fluidity of the four movements while no significant improvement was found for HGP or NHG.. These results suggest that learned information for this specific motor activity could be stored as internal inverse model andencoded in force coordinates

Haptic guidance improves the visuo-manual tracking of trajectories, in "PLoS ONE

Background: Learning to perform new movements is usually achieved by following visual demonstrations. Haptic guidance by a force feedback device is a recent and original technology which provides additional proprioceptive cues during visuomotor learning tasks. The effects of two types of haptic guidances-control in position (HGP) or in force (HGF)–on visuomanual tracking (‘‘following’’) of trajectories are still under debate. Methodology/Principals Findings: Three training techniques of haptic guidance (HGP, HGF or control condition, NHG, without haptic guidance) were evaluated in two experiments. Movements produced by adults were assessed in terms of shapes (dynamic time warping) and kinematics criteria (number of velocity peaks and mean velocity) before and after the training sessions. Trajectories consisted of two Arabic and two Japanese-inspired letters in Experiment 1 and ellipses in Experiment 2. We observed that the use of HGF globally improves the fluency of the visuo-manual tracking of trajectories while no significant improvement was found for HGP or NHG. Conclusion/Significance: These results show that the addition of haptic information, probably encoded in force coordinates, play a crucial role on the visuo-manual tracking of new trajectories

Figure 1

<p>Schematic view of haptic guidances: (a) Haptic guidance in position (HGP); the force felt by the user at time <i>t</i> is proportional to displacement between the current user position and the theoretical position on the model trajectory; (b) Haptic guidance in force (HGF); the force felt by the user at time <i>t</i> is the same as the force existing for the theoretical trajectory at the same time.</p

Letters proposed in experiment 1: Letters 1 and 2 are Arabic and letters 3 and 4 are “Japanese-like” letters.

<p>Letters proposed in experiment 1: Letters 1 and 2 are Arabic and letters 3 and 4 are “Japanese-like” letters.</p