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

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

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

Risk of falling assessment at home using an instrumented insole and Smartphone in One-Leg Standing (OLS) test

The risk of falling in elderly persons with neurodegenerative disease as Parkinson’s disease is generally assessed by clinical tests such as the Timed Up and Go test, the Tinetti test, the oneleg standing test, and others. Most of these tests are performed in a clinical environment, which could lead to spending time and money. Current studies have therefore shown that some clinical tests could be also made at home by using wearable devices based on inertial sensors. However, the experimental protocol used is not often straightforward and does not taken into account the environment conditions such as the type of soil. In addition, the clinical scores or gait abnormalities detection should be interpreted by a physiotherapist or by a house doctor. In this paper, we propose an automatic version of the one-leg standing (OLS) test for risk of falling assessment by using a smartphone and an instrumented insole over four types of ground. The instrumented insole and our application running on Android can be used at home as a diagnostic aid tool for analyzing the performance of elderly people in OLS test. Our work suggests that there is an inverse relationship between the OLS scores from the smartphone and the risk of falling. The score level can be used as a motivation in order to improve the physical condition of elderly