Exploitation of haptic renderings to communicate risk levels of falling

Falls represent a major cause of injury that could lead to death. This observation is even more accentuated in the elderly. Indeed, with aging comes some deterioration (gait disturbances, balance disorders, and sensory motor impairments) that may lead to falls. The research project presented in this thesis is focused on the problem of reducing the risk level of falling. This study proposes a solution for the communication of haptic information to reduce the risk of falling. This solution is part of the design of a haptic communication system in a controlled environment. This new system introduces the notion of haptic perception through the communication of information by touch using the foot, which the literature does not generally mention. For the design of this system, we first studied the use of tactile stimuli to evaluate the possibility of communicating a risk level through a haptic modality. Then, having hypothesized that some factors could influence the communication of stimuli representing the risk levels of falling, we conducted a second study to evaluate the effect of auditory disturbances during the communication of these stimuli. Third, to determine whether the user had the necessary time to act after the perception of the risk level, we analyzed a variation of the simple reaction time when walking on different types of soil. These results encouraged us to do a fourth assessment of reaction time using a new device coupled with a smartphone that can be positioned at different locations on the body. Several experiments have been done to validate each of the steps. With this, we can now communicate a risk level of falling to users through the haptic channel using an active device and easily differentiable stimuli. In addition, we can evaluate auditory factors during such a haptic perception. Finally, we can evaluate the physiological characteristics of the users (response time) while seated and while walking on different types of soil. Les chutes représentent une cause majeure de blessures pouvant entraîner la mort. Cette observation est encore plus accentuée chez les personnes âgées. En effet, avec le vieillissement, certaines détériorations (troubles de la démarche, troubles de l’équilibre, troubles sensorimoteurs) peuvent entraîner des chutes. Le projet de recherche présenté dans cette thèse fait partie du problème de la réduction du risque de chute. En particulier, cette étude propose une solution au problème de la réduction du risque de chute par la perception haptiques. Cette solution intègre la conception d’un système de communication haptique dans un environnement contrôlé. Ce nouveau système introduit la notion de perception haptique à travers la communication de l’information par le toucher avec le pied, que la littérature ne mentionne généralement pas. Pour cela nous avons d’abord étudié l’utilisation de stimuli tactiles pour évaluer la possibilité de communiquer un niveau de risque par la modalité haptique. Puis, ayant émis l’hypothèse que certains facteurs pourraient influencer la communication de ces stimuli, nous avons mené une deuxième étude pour évaluer l’impact des perturbations auditives lors de la perception haptique du niveau de risque. Troisièmement, afin de savoir si l’utilisateur avait le temps nécessaire pour agir après la perception du niveau de risque, nous avons analysé la variation du temps de réaction simple en marchant sur différents types de sols. Les résultats obtenus dans cette dernière étude nous ont motivé à faire une quatrième évaluation du temps de réaction mais en utilisant un nouveau dispositif couplé à un smartphone qui peut être positionné à différents endroits du corps. Plusieurs expériences ont été réalisées pour valider chacune des étapes. Avec toutes ces études, nous pouvons maintenant communiquer aux utilisateurs un niveau de risque à travers le canal haptique en utilisant un dispositif actif et des stimuli facilement différentiables. En outre, nous pouvons évaluer les facteurs externes (auditifs) au cours d’une telle perception haptique. Enfin, nous pouvons évaluer les caractéristiques physiologiques des utilisateurs (temps de réponse) en position assise et en marchant sur différents types de sols

Impact of auditory distractions on haptic messages presented under the foot

When compared to vision and audition, communication capabilities of the haptic channel remain underexploited. In this paper, we investigate the impact of auditory distractions on the learning of haptic messages presented under the foot plantar. From a set of six haptic messages that have been designed in order to be easily differentiable one from another, participants have to select four. With and without the presence of auditory distractions, we evaluate the completion time and the number of iteration required to reach an identification rate greater than 95%. For both measures, we observed that having auditory distractions was detrimental to the performances of users

Reaction time to vibrotactile messages on different types of soil

This study investigates the Reaction Time (RT) to vibrotactile messages presented under the foot plantar on different types of soil. We determine whether reaction time varies while walking on different types of soil (mobile situation). A total of six young participants (n=6) aged between 21 and 28 took part firstly in this study where they had to walk on five types of soil (concrete, carpet, foam, gravel, and sand). The methodology includes 360 repeated measures. The findings have consistently revealed a decrease of reaction time to vibrotactile messages when walking on the three deformable soils (foam, gravel, and sand)

Response time to a vibrotactile stimulus presented on the foot at rest and during walking on different surfaces

This study investigates the simple reaction time (SRT) and response time (RT) to a vibrotactile stimulus presented on two body locations at the lower extremity of the foot on different types of surface during walking. We determined RTs while walking on Concrete, Foam, Sand, and gravel surface. Also, for RT, we evaluated two vibrotactile stimulus (VS) locations on the lower extremity: the ankle (AL) and under the foot plantar (FP). A total of 21 young adult participants (n = 21), aged mean 24 ± 2.9 years, took part in a two-session experiment with two main conditions (at rest and while walking on four types of surface). The control session included 2016 repeated measures, with one-way and two-way ANOVA analyses. The findings have consistently revealed slowness of RT to VS, in particular on sand and gravel surface. In addition, we found that body location has a significant effect on RT in certain surfaces. These results showed that RTs increased with environment changes during the performance of dual tasks

Design and Effect of Continuous Wearable Tactile Displays

Our sense of touch is one of our core senses and while not as information rich as sight and hearing, it tethers us to reality. Our skin is the largest sensory organ in our body and we rely on it so much that we don\u27t think about it most of the time. Tactile displays - with the exception of actuators for notifications on smartphones and smartwatches - are currently understudied and underused. Currently tactile cues are mostly used in smartphones and smartwatches to notify the user of an incoming call or text message. Specifically continuous displays - displays that do not just send one notification but stay active for an extended period of time and continuously communicate information - are rarely studied. This thesis aims at exploring the utilization of our vibration perception to create continuous tactile displays. Transmitting a continuous stream of tactile information to a user in a wearable format can help elevate tactile displays from being mostly used for notifications to becoming more like additional senses enabling us to perceive our environment in new ways. This work provides a serious step forward in design, effect and use of continuous tactile displays and their use in human-computer interaction. The main contributions include: Exploration of Continuous Wearable Tactile Interfaces This thesis explores continuous tactile displays in different contexts and with different types of tactile information systems. The use-cases were explored in various domains for tactile displays - Sports, Gaming and Business applications. The different types of continuous tactile displays feature one- or multidimensional tactile patterns, temporal patterns and discrete tactile patterns. Automatic Generation of Personalized Vibration Patterns In this thesis a novel approach of designing vibrotactile patterns without expert knowledge by leveraging evolutionary algorithms to create personalized vibration patterns - is described. This thesis presents the design of an evolutionary algorithm with a human centered design generating abstract vibration patterns. The evolutionary algorithm was tested in a user study which offered evidence that interactive generation of abstract vibration patterns is possible and generates diverse sets of vibration patterns that can be recognized with high accuracy. Passive Haptic Learning for Vibration Patterns Previous studies in passive haptic learning have shown surprisingly strong results for learning Morse Code. If these findings could be confirmed and generalized, it would mean that learning a new tactile alphabet could be made easier and learned in passing. Therefore this claim was investigated in this thesis and needed to be corrected and contextualized. A user study was conducted to study the effects of the interaction design and distraction tasks on the capability to learn stimulus-stimulus-associations with Passive Haptic Learning. This thesis presents evidence that Passive Haptic Learning of vibration patterns induces only a marginal learning effect and is not a feasible and efficient way to learn vibration patterns that include more than two vibrations. Influence of Reference Frames for Spatial Tactile Stimuli Designing wearable tactile stimuli that contain spatial information can be a challenge due to the natural body movement of the wearer. An important consideration therefore is what reference frame to use for spatial cues. This thesis investigated allocentric versus egocentric reference frames on the wrist and compared them for induced cognitive load, reaction time and accuracy in a user study. This thesis presents evidence that using an allocentric reference frame drastically lowers cognitive load and slightly lowers reaction time while keeping the same accuracy as an egocentric reference frame, making a strong case for the utilization of allocentric reference frames in tactile bracelets with several tactile actuators

Use of tactons to communicate a risk level through an enactive shoe

The use of the haptic channel in multimodal interfaces holds several advantages for communication, one of them being that it allows decreasing the load of the visual and auditory channels. Tactons are abstract messages that can be used to communicate non-visually. In this paper we describe a study in which we tested if a set of four tactons can be used to convey a risk level (four states) through an enactive shoe. To this end, two experiments have been run. In the first experiment with 14 participants, we used a multidimensional scale analysis to identify the six most different tactons from an initial set of 30 tactons. In the second experiment (with 38 participants), we evaluated participants’ ability to recognize four preselected tactons among these six. For each trial, participants had to perform 12 identifications (three times for each tacton) until they reached a score greater than 95%. The number of trials required and the completion time are analyzed. We found that the repetition significantly improves the recognition rate of tactons but does not speed up the completion time

Proceedings of the 6th international conference on disability, virtual reality and associated technologies (ICDVRAT 2006)

The proceedings of the conferenc