La navigation repose en majeure partie sur la vision puisque ce sens nous permet de rassembler des informations spatiales de façon simultanée et de mettre à jour notre position par rapport à notre environnement. Pour plusieurs aveugles qui se fient à l’audition, le toucher, la proprioception, l’odorat et l’écholocation pour naviguer, sortir à l’extérieur de chez soi peut représenter un défi considérable. Les recherches sur le circuit neuronal de la navigation chez cette population en particulier s’avèrent donc primordiales pour mieux adapter les ressources aux handicapés visuels et réussir à les sortir de leur isolement. Les aveugles de naissance constituent aussi une population d’intérêt pour l’étude de la neuroplasticité. Comme leur cerveau s’est construit en absence d’intrant visuel, la plupart des structures reliées au sens de la vue sont réduites en volume par rapport à ceux de sujets voyants. De plus, leur cortex occipital, une région normalement dédiée à la vision, possède une activité supramétabolique au repos, ce qui peut représenter un territoire vierge pouvant être recruté par les autres modalités pour exécuter diverses tâches sensorielles. Plusieurs chercheurs ont déjà démontré l’implication de cette région dans des tâches sensorielles comme la discrimination tactile et la localisation auditive. D’autres changements plastiques de nature intramodale ont aussi été observés dans le circuit neuronal de la navigation chez ces aveugles. Par exemple, la partie postérieure de l’hippocampe, impliquée dans l’utilisation de cartes mentales, est réduite en volume alors que la section antérieure est élargie chez ces sujets. Bien que ces changements plastiques anatomiques aient bel et bien été observés chez les aveugles de naissance, il reste toutefois à les relier avec leur aspect fonctionnel. Le but de la présente étude était d’investiguer les corrélats neuronaux de la navigation chez l’aveugle de naissance tout en les reliant avec leurs habiletés spatio-cognitives. La première étude comportementale a permis d’identifier chez les aveugles congénitaux une difficulté d’apprentissage de routes tactiles construites dans des labyrinthes de petite échelle. La seconde étude, employant la technique d’imagerie par résonance magnétique fonctionnelle, a relié ces faiblesses au recrutement de régions cérébrales impliquées dans le traitement d’une perspective égocentrique, comme le lobule pariétal supérieur droit. Alors que des sujets voyants aux yeux bandés excellaient dans la tâche des labyrinthes, ces derniers recrutaient des structures impliquées dans un traitement allocentrique, comme l’hippocampe et le parahippocampe. Par ailleurs, la deuxième étude a confirmé le recrutement du cortex occipital dans une tâche de navigation chez les aveugles seulement. Ceci confirme l’implication de la plasticité intermodale dans des tâches cognitives de plus haut niveau, comme la navigation. / Navigation is predominately based on vision as it gathers spatial information simultaneously and allows a continuous update of our position relative to space. For many blind people who rely mainly on auditive, haptic, proprioceptive, olfactive and echolocating cues to navigate, leaving outside their home can be a challenge. Research on the navigational neural network in this particular population is therefore crucial to better adapt resources for visually impaired people and free them from isolation. Congenitally blind subjects are also an interesting population for the study of neuroplasticity. As their brain was built without any visual input, most structures related to vision are reduced in volume compared to those of seeing subjects. Moreover, their occipital cortex, a region normally dedicated to vision, has a suprametabolic activity at rest, which could represent a virgin territory that can be recruited by other modalities to accomplish various sensory tasks. Recently some researchers have demonstrated the involvement of this region in sensory tasks such as tactile discrimination and auditive localisation. Other intramodal plastic changes have also been observed in the blind’s navigational neural network. The posterior part of hippocampus, involved in cognitive mapping, is reduced in volume while the anterior section is enlarged in blind subjects. Although some anatomical plastic changes have been observed in congenitally blind’s brain navigational system, their functional aspect remains to be elucidated. The purpose of this study was to investigate the neural correlates of navigation in congenital blindness and to link them with the blinds’ spatio-cognitive skills. The first behavioral study identified route learning difficulties in congenitally blind participants when they were ask to navigate inside small-scaled tactile mazes. Using functional magnetic resonance imagery in the second study, these problems were associated with the recruitment of brain regions involved in an egocentric perspective processing, such as right superior parietal lobule. While blindfolded seeing subjects excelled in the maze task, they recruited structures involved in allocentric processing, such as hippocampus and parahippocampus. Moreover, the second study confirmed the recruitment of occipital cortex in a navigation task for blind subjects only. This strengthens the involvement of crossmodal plasticity in higher level cognitive tasks, such as navigation.

INTRODUCTION - The ability to maintain stability while standing given by function of multisenzory system consists of vision, somatosensory and vestibular system and integration of the CNS. Due to aging there is a decrease of functional capacity of the organism, including these systems, resulting in a deterioration of the balance. Examination of subjective visual and haptic vertical is sensitive diagnostic criterion for functionality of these systems. OBJECTIVE - To compare the ability of verticality perception in young and elderly. METHODS - We examined 64 probands in visual and haptic subjective vertical. The first group consisted of 30 subjects aged 20 to 30 years. In the second group there were 34 people aged over 60. RESULTS - The values of the subjective visual vertical not differ between groups (0.1 ± 0.75 ř for the young and 0.1 ± 1.91 ř for seniors). Results of subjective haptic vertical differed on the significance level of p = 0.004 (0.8 ± 3.67 in the young and 3.7 ± 4.15 for seniors). CONCLUSION - Because subjective haptic vertical is diagnostic criterion mainly for the somatosensory system, we can assume that this particular system is responsible for a decrease in functional capacity and deterioration of stability in the elderly.

This thesis investigates cinema’s attempts to engage in a dialogue with the trace of the physical body. My concern is with the on-screen presentation of the body rather than its treatment as a representation of gender, sexuality, race, age, or class. I examine specifically The Elephant Man (Lynch, 1980), Crash (Cronenberg, 1996), Attenberg (Tsangari, 2010), Taxidermia (Pálfi, 2006), and Sokurov’s family trilogy (Mother and Son, 1997; Father and Son, 2003; and Alexandra, 2007). The recurring tropes in these seven films include references to the medical gaze (both objective and objectifying) and haptic visuality which privileges sensual, close engagement with the image of the material object. I consider the medical and the haptic as metaphors for depictions of the body in cinema. To develop my analysis, I draw on the works of Michel Foucault, Laura U. Marks and Vivian Sobchack amongst others. I conclude that the discussed films, preoccupied with images of corporeal forms, criticise cinema’s conventional treatment of the body as simply a vessel for a goal-driven character and portray bodies which appear to consciousness in their own right.

Le docking moléculaire est une tâche complexe, difficile à appréhender pour une personne seule. C’est pourquoi, nous nous proposons d’étudier la distribution cognitive des charges de travail à travers la collaboration. Une plate-forme distribuée de déformation moléculaire interactive a été mise en place afin d’étudier les avantages mais aussi les limites et les contraintes du travail collaboratif étroitement couplé. Cette première étude, basée sur trois expérimentations, a permis de valider l’intérêt d’une approche collaborative pour des tâches complexes à fort couplage. Cependant, elle a mis en évidence des conflits de coordination ainsi que des problématiques liées à la dynamique d’un groupe. Suite à cette première étude, nous avons proposés une nouvelle configuration de travail associée à des métaphores de communication haptiques afin d’améliorer la communication et les interactions entre les différents collaborateurs. Une dernière expérimentation avec des biologistes a permis de montrer l’utilité de la communication haptique pour le travail collaboratif sur des tâches complexes à fort couplage. / Molecular docking is a very complex task that can not be deal by only one user. Based on this observation, we propose to study the cognitive workload distribution on group of users in collaboration. For this purpose, we implement a distributed platform to interactively manipulate and deform structures of the molecules. With this platform, we want to study the assets of the closely coupled collaboration but also highlight the constraints and the drawbacks. Based on three experimentations, the study validate the concept of workload distribution in the closely coupled collaboration. However, it highlights limits with coordination conflicts through communication problem. Moreover, some difficulties have been encountered with the dynamic in a group of collaborators.Based on these results, we proposed a new working configuration coupled with new haptic communication metaphors to improve the communication and the coordination between the members of the group. These propositions have been evaluated in a fourth experimentation introducing biologists. The results show the importance of the haptic communication to improve the coordination in closely coupled collaboration.

La perception de la verticale repose sur l’intégration des informations vestibulaires, visuelles et somesthésiques. Elle est généralement étudiée dans la modalité visuelle (VVS) ou haptique (VHS) et plus rarement dans la modalité visuo-haptique (VVHS). Cette modalité pose la question de l’intégration des informations mises en jeu par ces deux modalités dans la perception multimodale et du modèle cognitif sous-jacent. Se pose également la question de l'effet des lésions cérébrales perturbant la perception spatiale (hémi-négligence) dans la perception de la verticale.Une comparaison des VVS, VHS et VVHS est réalisée dans les quatre premières études de cette thèse, chez des participants sains jeunes et plus âgés et chez des patients cérébro-lésés droits avecou sans troubles visuo-spatiaux. Les performances observées sont proches de la verticale gravitaire chez les participants sains pour les VVS et VVHS. La VHS (avec la main droite) est déviée, dans le sens horaire chez les jeunes participants et anti-horaire pour les participants plus âgés. La présence d’un cadre visuel perturbe les VVS et VVHS chez les participants dépendants à l'égard du champ.Les patients cérébro-lésés droits présentent une déviation anti-horaire des trois verticales, plus marquée pour la VHS. Les VVHS mesurées sont correctement prédites, dans toutes les conditions,par la somme des VVS et VHS pondérées par leurs précisions relatives. La variance de la VVHS est moindre que les variances des VVS et VHS. La VHS, systématiquement déviée dans ces quatre premières études, fait l’objet d’une évaluation détaillée dans les deux dernières études de cette thèse. Les résultats montrent que la VHS est déviée dans le sens horaire avec la main droite, dans le sens anti-horaire avec la main gauche chez les participants sains jeunes ; les déviations s’inversent avec l’âge. Par ailleurs, les performances sont systématiquement déviées dans le sens des positions initiales. Considérés ensemble, ces résultats montrent que la perception de la verticale implique les informations mises en jeu par les modalités visuelle et haptique mais avec une prépondérance de la première. Ce travail de thèse montre ainsi que la perception de la verticale subjective repose sur une intégration multimodale pondérée des informations sensorielles en accord avec le modèle statistique bayésien du maximum de vraisemblance. Ce mode d'intégration multi-sensorielle n'est pas altéré par l’âge ou la présence de lésions cérébrales affectant la perception visuo-spatiale. Plusieurs pistes restent à explorer, notamment, le poids de la contribution des informations vestibulaires dans la verticale subjective. / The perception of the vertical direction is achieved through vestibular, visual and somatosensory information integration. It is studied in the visual (SVV), haptic (SHV) and less often in the visuo-haptic modality (SVHV). The latter raises the question of the integration of visual the information involved in the visual and haptic modalities and of the cognitive model underlying this integration. SVV, SHV and SVHV were compared in the first four studies of this thesis, inhealthy young and older subjects and in right-brain damaged patients with or without visuo-spatial disorders. Performances were closed to the gravity in healthy participants, for SVV as well as forSVHV. VHS, assessed with the right hand, was tilted clockwise in young participants and anticlockwise in older participants. The presence of a visual frame disrupted SVV and SVHV. The right-brain damaged patients had an anti-clockwise deviation of SVV and SVHV and the SHV was even more tilted. SVHV was well predicted from the sum of the SVV and SHV weighted by their relative variances in all conditions and the SVHV variances were lesser. SHV was evaluated in detail in the two last studies of this thesis because of the systematic tilt in the first four studies. The results show that the SHV is tilted clockwise with the right hand and anti-clockwise with the left hand in young healthy subjects. Moreover, deviations reversed in older group and performances are systematically tilted toward the initial positions in the two groups. Taken together, these results show that the way participants integrate visual and haptic information fits the maximum like lihoodmodel with a greater weighting of information available in visual modality and that ageing and right-brain lesions does not alter the multisensory integration. The weight of vestibular information in the subjective vertical, which has not been evaluated per se in this thesis, needs further investigations.

Le développement rapide des nouvelles technologies numériques est en passe de révolutionner l’enseignement classique de l’odontologie comme dans de nombreuses spécialités médicales. En effet, l’avènement de nouveaux dispositifs alliant réalité virtuelle et dispositif haptique permettant de simuler au plus juste les gestes techniques de l’odontologie, laisse entrevoir la possibilité d’évaluer plus objectivement les compétences des futurs Chirurgiens-Dentistes et de renforcer la formation traditionnelle. Au travers de différentes expérimentations pédagogiques dans les domaines de l’implantologie, de la dentisterie restauratrice et de la chirurgie orale, nous avons voulu : (i) évaluer l’impact de la simulation haptique sur la formation en odontologie en nous focalisant sur l’implantologie et la dentisterie restauratrice ; (ii) définir de nouveaux paramètres pédagogiques pour essayer de les évaluer objectivement et estimer l’importance de la vision 3D en simulation / The rapid development of new digital technologies is revolutionizing the classical teaching of dentistry as in many medical specialties. Indeed, the advent of new devices combining virtual reality with a haptic device allowing to simulate the technical gestures of odontology, suggests the possibility to evaluate the skills of future Dentists more objectively and to strengthen traditional training. Through various educational experiments in the fields of implantology, restorative dentistry and oral surgery, we wanted to: (i) assess the impact of haptic simulation on odontology training by focusing on implantology and restorative dentistry ; (ii) define new objectively evaluable pedagogical parameters and to estimate the importance of 3D vision in simulation

Les robots humanoïdes sont les plus appropriés pour travailler en coopération avec l'homme. En effet, puisque les humains sont naturellement habitués à collaborer entre eux, un robot avec des capacités sensorielles et de locomotion semblables aux leurs, sera le plus adapté. Cette thèse vise à rendre les robot humanoïdes capables d'aider l'homme, afin de concevoir des 'humanoïdes collaboratifs'. On considère ici la tâche de transport collaboratif d'objets. D'abord, on montre comment l'utilisation simultanée de vision et de données haptiques peut améliorer la collaboration. Une stratégie combinant asservissement visuel et commande en admittance est proposée, puis validée dans un scénario de transport collaboratif homme/humanoïde.Ensuite, on présente un algorithme de génération de marche, prenant intrinsèquement en compte la collaboration physique. Cet algorithme peut être spécifié suivant que le robot guide (leader) ou soit guidé (follower) lors de la tâche. Enfin, on montre comment le transport collaboratif d'objets peut être réalisé dans le cadre d'un schéma de commande optimale pour le corps complet. / Humanoid robots provide many advantages when working together with humans to perform various tasks. Since humans in general have alot of experience in physically collaborating with each other, a humanoid with a similar range of motion and sensing has the potential to do the same.This thesis is focused on enabling humanoids that can do such tasks together withhumans: collaborative humanoids. In particular, we use the example where a humanoid and a human collaboratively carry and transport objectstogether. However, there is much to be done in order to achieve this. Here, we first focus on utilizing vision and haptic information together forenabling better collaboration. More specifically the use of vision-based control together with admittance control is tested as a framework forenabling the humanoid to better collaborate by having its own notion of the task. Next, we detail how walking pattern generators can be designedtaking into account physical collaboration. For this, we create leader and follower type walking pattern generators. Finally,the task of collaboratively carrying an object together with a human is broken down and implemented within an optimization-based whole-bodycontrol framework.

A informação háptica fornecida pelo toque leve (TL) e pelas âncoras reduz a oscilação postural durante a postura em pé. No entanto, não está claro se esse benefício permaneceria na presença de tarefas cognitivas em adultos jovens e em idosos com e sem histórico de quedas. Assim, os objetivos foram: 1) investigar os efeitos das âncoras e de tarefas cognitivas visuais e auditivas no controle postural em adultos jovens em uma tarefa postural desafiadora (Estudo 1); 2) investigar o efeito das dicas hápticas fornecidas pelo TL e pelas âncoras durante a realização de uma tarefa cognitiva visual idosos com e sem histórico de quedas quando na postura em pé (Estudo 2). Sessenta e quatro indivíduos foram distribuídos em três grupos: adultos jovens (n=20), idosos caidores (n=22) e idosos não caidores (n=22). Para os adultos jovens (Estudo 1), a tarefa consistiu em permanecer em pé em uma trave de equilíbrio com pés distantes na largura dos ombros sem e com o uso das âncoras, sem e com tarefas cognitivas (teste visual de Stroop adaptado e tarefa auditiva de monitoramento de dígitos). Para os idosos (Estudo 2), a tarefa consistiu em permanecer na postura ereta com os pés unidos desempenhando seis condições experimentais combinando dicas hápticas (sem contato, TL e âncoras) e na presença ou ausência da tarefa cognitiva visual (teste visual de Stroop adaptado). Os resultados do estudo 1 mostraram que para os adultos jovens os benefícios do uso das âncoras não foram influenciados pelas tarefas cognitivas. Mesmo em superfície desafiadora, a oscilação postural foi reduzida para facilitar a execução das tarefas cognitivas. Os resultados do estudo 2 revelaram que os idosos com e sem histórico de quedas se beneficiaram igualmente da adição de dicas hápticas. A presença da tarefa cognitiva-visual reduziu a oscilação postural em ambos os grupos. De maneira geral, tanto o TL quanto as âncoras foram eficazes na redução da oscilação postural em adultos jovens e idosos com e sem histórico de quedas, sugerindo que a informação háptica foi capaz de beneficiar o controle postural mesmo em condições de tarefas cognitivas, demonstrando que jovens e idosos, particularmente aqueles com histórico de quedas, foram capazes de modular funcionalmente o controle postural de forma a facilitar a execução das tarefas cognitivas. / Haptic information provided by the light touch (LT) and the anchors reduce the postural sway during upright standing. It is unclear whether this benefit would remain in the presence of cognitive tasks in young and older adults with and without a history of falls. Thus, the aims were: 1) to investigate the effects of the anchors and the visual and auditory cognitive tasks on postural control in young adults in a challenging balancing task (Study 1); 2) to investigate the effect of haptic input provided by LT and anchors while performing a cognitive-visual task in older adults with and without a history of falls when standing upright (Study 2). Sixtyfour individuals were divided into three groups: young adults (n=20), faller older adults (n=22) and non-faller older adults (n=22). For the young adults (Study 1), the task consisted in standing upright on a balance beam with feet apart at shoulders width while performing 6 experimental conditions combining the anchors (with or without) and the cognitive tasks (none, the adapted visual Stroop test and the auditory digit monitoring task). For the older adults (Study 2), the task consisted in standing upright with feet together while performing six experimental conditions combining haptic cues (none, LT, and anchors) and the presence/absence of the cognitive-visual task (the adapted visual Stroop test). The results of the study 1 showed that the cognitive tasks did not affect the benefits of the anchors for the young adults. Even on a challenging surface, the postural sway reduced to facilitate the execution of the cognitive tasks. The results of the study 2 revealed that the older adults benefited similarly from the haptic cues, independently their history of falls. The presence of the cognitive-visual task reduced the postural sway in both groups. In general, both LT and anchors were effective to reduce postural sway in young and older (fallers and non-fallers) adults, suggesting that the haptic information was able to benefit the postural control even with cognitive tasks, demonstrating that young and older adults, particularly those with a history of falls, were able to functionally modulate their postural control to facilitate the execution of the cognitive tasks.

A informação háptica fornecida pelo toque leve (TL) e pelas âncoras reduz a oscilação postural durante a postura em pé. No entanto, não está claro se esse benefício permaneceria na presença de tarefas cognitivas em adultos jovens e em idosos com e sem histórico de quedas. Assim, os objetivos foram: 1) investigar os efeitos das âncoras e de tarefas cognitivas visuais e auditivas no controle postural em adultos jovens em uma tarefa postural desafiadora (Estudo 1); 2) investigar o efeito das dicas hápticas fornecidas pelo TL e pelas âncoras durante a realização de uma tarefa cognitiva visual idosos com e sem histórico de quedas quando na postura em pé (Estudo 2). Sessenta e quatro indivíduos foram distribuídos em três grupos: adultos jovens (n=20), idosos caidores (n=22) e idosos não caidores (n=22). Para os adultos jovens (Estudo 1), a tarefa consistiu em permanecer em pé em uma trave de equilíbrio com pés distantes na largura dos ombros sem e com o uso das âncoras, sem e com tarefas cognitivas (teste visual de Stroop adaptado e tarefa auditiva de monitoramento de dígitos). Para os idosos (Estudo 2), a tarefa consistiu em permanecer na postura ereta com os pés unidos desempenhando seis condições experimentais combinando dicas hápticas (sem contato, TL e âncoras) e na presença ou ausência da tarefa cognitiva visual (teste visual de Stroop adaptado). Os resultados do estudo 1 mostraram que para os adultos jovens os benefícios do uso das âncoras não foram influenciados pelas tarefas cognitivas. Mesmo em superfície desafiadora, a oscilação postural foi reduzida para facilitar a execução das tarefas cognitivas. Os resultados do estudo 2 revelaram que os idosos com e sem histórico de quedas se beneficiaram igualmente da adição de dicas hápticas. A presença da tarefa cognitiva-visual reduziu a oscilação postural em ambos os grupos. De maneira geral, tanto o TL quanto as âncoras foram eficazes na redução da oscilação postural em adultos jovens e idosos com e sem histórico de quedas, sugerindo que a informação háptica foi capaz de beneficiar o controle postural mesmo em condições de tarefas cognitivas, demonstrando que jovens e idosos, particularmente aqueles com histórico de quedas, foram capazes de modular funcionalmente o controle postural de forma a facilitar a execução das tarefas cognitivas. / Haptic information provided by the light touch (LT) and the anchors reduce the postural sway during upright standing. It is unclear whether this benefit would remain in the presence of cognitive tasks in young and older adults with and without a history of falls. Thus, the aims were: 1) to investigate the effects of the anchors and the visual and auditory cognitive tasks on postural control in young adults in a challenging balancing task (Study 1); 2) to investigate the effect of haptic input provided by LT and anchors while performing a cognitive-visual task in older adults with and without a history of falls when standing upright (Study 2). Sixtyfour individuals were divided into three groups: young adults (n=20), faller older adults (n=22) and non-faller older adults (n=22). For the young adults (Study 1), the task consisted in standing upright on a balance beam with feet apart at shoulders width while performing 6 experimental conditions combining the anchors (with or without) and the cognitive tasks (none, the adapted visual Stroop test and the auditory digit monitoring task). For the older adults (Study 2), the task consisted in standing upright with feet together while performing six experimental conditions combining haptic cues (none, LT, and anchors) and the presence/absence of the cognitive-visual task (the adapted visual Stroop test). The results of the study 1 showed that the cognitive tasks did not affect the benefits of the anchors for the young adults. Even on a challenging surface, the postural sway reduced to facilitate the execution of the cognitive tasks. The results of the study 2 revealed that the older adults benefited similarly from the haptic cues, independently their history of falls. The presence of the cognitive-visual task reduced the postural sway in both groups. In general, both LT and anchors were effective to reduce postural sway in young and older (fallers and non-fallers) adults, suggesting that the haptic information was able to benefit the postural control even with cognitive tasks, demonstrating that young and older adults, particularly those with a history of falls, were able to functionally modulate their postural control to facilitate the execution of the cognitive tasks.

Submitted by PPG Ci?ncia da Computa??o (ppgcc@pucrs.br) on 2018-07-26T19:57:26Z No. of bitstreams: 1 THOMAS VOLPATO DE OLIVEIRA_DIS.pdf: 2340160 bytes, checksum: a77fc7c024da22cb1ea18eec69501d7e (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-08-02T12:22:16Z (GMT) No. of bitstreams: 1 THOMAS VOLPATO DE OLIVEIRA_DIS.pdf: 2340160 bytes, checksum: a77fc7c024da22cb1ea18eec69501d7e (MD5) / Made available in DSpace on 2018-08-02T12:38:03Z (GMT). No. of bitstreams: 1 THOMAS VOLPATO DE OLIVEIRA_DIS.pdf: 2340160 bytes, checksum: a77fc7c024da22cb1ea18eec69501d7e (MD5) Previous issue date: 2017-08-23 / Realidade virtual ? uma tecnologia que permite aos seus usu?rios visualizar e interagir com ambientes virtuais (AV) 3D em tempo real. Um ambiente virtual colaborativo (AVC) ? um tipo de AV que permite que dois ou mais usu?rios estejam juntos no mesmo ambiente virtual. Ambientes virtuais colaborativos t?m algumas dificuldades que AV comuns n?o t?m. Por exemplo, diferentes t?cnicas s?o necess?rias a fim de permitir a dois usu?rios a manipula??o (mover ou girar) conjunta de um objeto virtual. Algumas dessas t?cnicas podem levar os usu?rios a realizarem movimentos n?o naturais. Este trabalho avalia o retorno h?ptico para deixar os usu?rios cientes de movimentos errados durante a manipula??o colaborativa de objetos. A t?cnica SkeweR foi utilizada como teste. Esta t?cnica ? baseada em crushing points, onde os usu?rios pegam o objeto pela primeira vez para simultaneamente mover e girar o objeto. Uma vez que os usu?rios mant?m a posi??o da m?o sobre o crushing point durante a manipula??o do objeto, a intera??o se torna mais natural, no sentido de que se torna mais similar ao processo real de segurar um objeto. Entretanto, devido ? falta de restri??es f?sicas de movimento, frequentemente, durante a intera??o, a m?o do usu?rio se move para fora do crushing point. Para solucionar este problema, este trabalho prop?e o uso de retorno t?til para informar os usu?rios sobre a dist?ncia entre a posi??o da m?o e o crushing point. O retorno t?til ? fornecido por um minimotor de vibra??o preso no polegar do usu?rio. Para validar o m?todo, fez-se um estudo com usu?rios em que estes deveriam realizar a manipula??o 3D de um objeto virtual. Este objeto precisava ser transladado e girado atrav?s de um caminho virtual ao longo de um fio virtual, do in?cio deste at? o fim. Durante a intera??o, os usu?rios manipularam um rastreador de posi??o com tr?s graus de liberdade (3DOF) e deveriam manter a posi??o do rastreador na mesma posi??o do crushing point. Durante as rodadas do experimento, os participantes testaram tr?s modalidades de intera??o: sem nenhum retorno, com retorno visual e com retorno t?til. O resultado dos testes mostrou que usu?rios realizaram manipula??es mais naturais quando estavam usando o retorno t?til. / Virtual reality is a technology that allows users to view and interact with a 3D virtual environment (VE) in real time. A collaborative virtual environment (CVE) is a type of VE that allows two or more users to be in the same virtual environment together. Collaborative virtual environments have some issues that simple VEs do not have. For example, different techniques are required in order to allow two users to manipulate (move or rotate) a virtual object together. Some of these techniques can lead users to do unnatural movements. This study evaluates haptic feedback to let users aware of wrong movements during a cooperative object manipulation. The SkeweR technique was used as a testbed. This technique is based on the use of crushing points, where the users grab the object for the first time, to simultaneously move/rotate an object. Once the users have their hands positioned on the crushing point during the object manipulation, the interaction becomes more natural, in the sense that it is more similar to the real process. However, due to the lack of any physical constraint to the users? movements, it is often noticed that the users? hands move away from the crushing point during the interaction. To solve this problem, this work proposes the usage of tactile feedback to inform the user about the distance between his hand and the crushing point. The tactile feedback is provided by a vibration micromotor attached to the user?s thumb. To validate the method, a user study based on the 3D manipulation of a virtual object was performed. The virtual object had to be translated and rotated through a virtual path along a virtual wire, from the beginning to the end of it. During the interaction, users manipulated a three degrees of freedom (3DOF) position tracker and were requested to keep this tracker in the same position of the crushing point. During the trials, the participants used three modalities of interaction: without any feedback, with a visual feedback and with tactile feedback. Results showed that the users do more natural manipulations when using tactile feedback.