Cette thèse présente l'importance des exosquelettes évolutifs des membres inférieurs pour les adolescents handicapés souffrant de troubles neuromusculaires et autres pathologies. Le nouveau terme " évolutif" décrit la capacité de l'exosquelette à grandir physiquement avec l'utilisateur, et à s'adapter à sa morphologie.Une analyse distincte des manifestations physiques qui subissent a été faite, en ce qui concerne la poussée de croissance pubertaire et les effets secondaires éventuelles. L'étude de la littérature montre qu'il n'existe pas de dispositif de réadaptation suffisamment adapté aux besoins d'un adolescent en pleine croissance en raison de la croissance rapide de ses membres et de la nature progressive de ses maladies. Comme c'est la première fois que le terme «évolutivité» est utilisé pour les exosquelettes, ses exigences fonctionnelles sont définies. Le développement mécatronique d'un exosquelette évolutif est aussi présenté, incluant le développement de son actionneur articulaire et sa structure mécanique.Enfin, les résultats préliminaires des performances de l'actionneur articulaire lors de la simulation des mouvements fonctionnels liés à la croissance montrent une grande capacité de suivi et d'exécution des mouvements basés sur les couples, tandis que les résultats liés à la structure évolutive montrent la capacité du système à s'adapter aux différents utilisateurs. / This thesis introduces the importance of the scalable lower limb exoskeletons for disabled teenagers suffering from neuromuscular disorders & other pathological conditions. The new term "scalable" describes the ability of the exoskeleton to physically grow up with the user and to be adapted to his/her morphology.A distinctive analysis of the physical manifestations that the patients experience has been done concerning the pubertal growth spurt and to the future secondary effects. The study of the literature shows that no rehabilitation device is customized enough to the needs of a growing teenagers due to the fast growth of their bodies and to the progressiveness nature of their diseases. As this is the first time the term "scalability" is brought up for exoskeletons, its functional requirements are defined in order to determine the constraints imposed on the design of the new exoskeleton. The mechatronics development of a scalable exoskeleton is presented, including the development of its joint actuator, its mechanical structure and attachments.Finally, the preliminary results of the joint actuator performance when simulating functional movements related to the growth show a high capability of trajectory following and executing torques based motions, while the findings associated with the scalable structure show the system able to be adapted to the different user sizes and ages.

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Recent technological developments have ushered in an exciting era for collaborative robots (cobots), which can operate in close proximity with humans, sharing and supporting task goals. While there is increasing research on the biomechanical and ergonomic consequences of using cobots, there is relatively little work on the potential motor-cognitive demand associated with these devices. These cognitive demands primarily stem from the need to form accurate internal (mental) models of robot behavior, while also dealing with the intrinsic motor-cognitive demands of physical co-manipulation tasks, and visually monitoring the environment to ensure safe operation. The primary aim of this work was to investigate the viability of eye-tracking measures for characterizing mental workload during the use of cobots, while accounting for the potential effects of learning, task-type, expertise, and age-differences. While eye-tracking is gaining traction in surgical/rehabilitation robotics domains, systematic investigations of eye tracking for studying interactions with industrial cobots are currently lacking. We conducted three studies in which participants of different ages and expertise levels learned to perform upper- and lower-limb tasks using a dual-armed cobot and a whole-body powered exoskeleton respectively, over multiple trials. Robot-control difficulty was manipulated by changing the joint impedance on one of the robot arms (for the dual-armed cobot). The first study demonstrated that when individuals were learning to interact with a dual-armed cobot to perform an upper-limb co-manipulation task simulated in a virtual reality (VR) environment, pupil dilation (PD) and stationary gaze entropy (SGE) were the most sensitive and reliable measures of mental workload. A combination of eye-tracking measures predicted performance with greater accuracy than experimental task variables. Measures of visual attentional focus were more sensitive to task difficulty manipulations than typical eye-tracking workload measures, and PD was most sensitive to changes in workload over learning. The second study showed that compared to walking freely, walking while using a complex whole-body powered exoskeleton: a) increased PD of novices but not experts, b) led to reduced SGE in both groups and c) led to greater downward focused gaze (on the walking path) in experts compared to novices. In the third study using an upper-limb co-manipulation task similar to Study 1, we found that the PD of younger adults reduced at a faster rate over learning, compared to that of older adults, and older adults showed a significantly greater drop in gaze transition entropy with an increase in task difficulty, compared to younger adults. Also, PD was sensitive to learning and robot-difficulty but not environmental-complexity (collisions with objects in the task environment), and gaze-behavior measures were generally more sensitive to environmental-complexity. This research is the first to conduct a comprehensive analysis of mental workload in physical human-robot interaction using eye-tracking measures. PD was consistently found to show larger effects over learning, compared to task difficulty. Gaze-behavior measures quantifying visual attention towards environmental areas of interest were found to show relatively large effects of task difficulty and should continue to be explored in future research. While walking in a powered exoskeleton, both novices and experts exhibited compensatory gaze strategies. This finding highlights potentially persistent effects of using cobots on visual attention, with potential implications to safety and situational awareness. Older adults were found to apply greater mental effort (indicated by sustained PD) and followed more constrained gaze patterns in order to maintain similar levels of performance to younger adults. Perceived workload measures could not capture these age-differences, thus highlighting the advantages of eye-tracking measures. Lastly, the differential sensitivity of pupillary- and gaze behavior metrics to different types of task demands highlights the need for future research to employ both kinds of measures for evaluating pHRI. Important questions for future research are the potential sensitivity of eye-tracking workload measures over long-term adaptations to cobots, and the potential generalizability of eye-tracking measures to real-world (non-VR) tasks. / Doctor of Philosophy / Collaborative robots (cobots) are an exciting and novel technology that may be used to assist human workers in manual industrial work, reduce physical demand, and potentially enable older adults to re-enter the workforce. However, relatively little is known about the potential cognitive demands that cobots may impose on the human user. Although intended to assist humans, some cobots have been found to be difficult to use, because of the time and effort that is needed to learn their control dynamics (i.e. to learn how to physically control them to perform a complex manual task). Thus, it is important to better understand the potential mental demand/workload that a human operator may experience, while using a cobot, and how this demand may vary over time and learning to use the cobot. Eye-tracking is a promising technique to measure a cobot-operators' mental workload, since it can provide various measures that correlate with the involuntary physiological response to mental workload (e.g. pupil dilation - PD), as well as voluntary gaze strategies (e.g. the durations and patterns of where people look) in order to perform a physical/motor task. Eye-tracking measures may be used to continuously and precisely evaluate whether a cobot imposes excessive workload on the human operator, and if high workload is observed, the cobot may be programmed to adapt its behavior to reduce workload. Although eye-tracking is gaining traction in surgical/rehabilitation robotics domains, systematic investigations of eye tracking for studying interactions with industrial cobots are currently lacking. We designed three studies in which we investigated 1) the ability of eye-tracking measures to measure changes in mental workload while participants learned to use a cobot under different difficulty-levels 2) the changes in pupil diameter and gaze behavior when participants walked while wearing a whole-body powered exoskeleton as opposed to walking freely, and potential differences between novice- and expert exoskeleton-users 3) the differences in mental workload and visual attention between younger and older adults while learning to use a cobot. The first and third studies used virtual reality (VR) to simulate the task environment, to allow for precise control over the presentation of stimuli. In study 1, we found that in higher difficulty-levels, participants' pupils were significantly more dilated, i.e., participants experienced higher mental workload, than in lower-difficulty levels. Also, PD gradually reduced as participants learned to better perform the task. In difficult task-conditions, participants gazed more frequently at the robot, and showed higher randomness (entropy) in their gaze patterns. The proportion of gaze falling on certain objects was at least as sensitive an indicator of task-difficulty, as PD and gaze entropy. In study 2, we found that walking in a whole-body exoskeleton was cognitively demanding, but only for novice participants. However, both novice and expert participants showed changes in their gaze patterns while walking in the exoskeleton – both groups lowered their gaze and focused on the walking path to a greater extent, compared to walking freely. Lastly, in study 3, we also found that older adults applied greater mental effort for maintaining similar levels of performance as younger adults. Older adults also exhibited more repetitive scanning patterns compared to younger adults, when task difficulty increased. This may have been due to potential reduction in the capacity to control attention with age. Our work demonstrates that eye-tracking measures are sensitive and reliable metrics of workload, and that different metrics are sensitive to different sources of workload. Specifically, PD was sensitive to robot-difficulty, and measures of visual attention were generally more sensitive to the complexity of the task environment. Important questions for future research are the potential changes in eye-tracking workload measures over longer time periods of learning to use cobots, and how these results generalize to real-world tasks that are not performed in virtual reality.

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Robotic exoskeletons are important tools in medicine for characterizing certain aspects of diseases, enabling physical therapy treatments, or providing assistance to those with impairments. One area in particular where these devices can make an impact is the study and treatment of scoliosis. First, I adapt a design of a robotic torso exoskeleton to serve the population most susceptible to scoliosis, female adolescents. I used the device to compare the torso stiffness of members of this group with and without scoliosis, and found an interaction effect of degree of freedom (DOF) and torso segment on translational stiffness, and an interaction effect of DOF and group on rotational stiffness. These results can inform the models used to create rigid orthoses for conservative treatment or to simulate the effects of surgical procedures. Second, I explore the effects of different types of augmented sensory feedback commonly used in scoliosis physical therapy. I compare visual and force feedback provided by the exoskeleton on one’s ability to replicate static poses and dynamic movements. I find that while force feedback leads to faster initial improvement, visual feedback may enable the user to learn finer details of the movement. Third, I design a torso exoskeleton for people with neuromotor impairments. People who are not able to sit up independently are at a high risk of developing neuromuscular scoliosis, and must balance the benefits of treatment with rigid orthoses, with the limits that these devices place on functional movements. The device allows users four degrees of freedom, to support functional movements such as reaching and pressure relief maneuvers, but prevents lateral translation and axial rotation, which can contribute to neuromuscular scoliosis. Together, these results demonstrate the potential for robotic exoskeletons in torso study, training, and assistance.

Knee osteoarthritis (KOA) is the primary cause of chronic immobility in populations over the age of 65. It is a joint degenerative disease in which the articular cartilage in the knee joint wears down over time, leading to symptoms of pain, instability, joint stiffness, and misalignment of the lower extremities. Without intervention, these symptoms gradually worsen over time, decreasing the overall knee range of motion (ROM) and ability to walk. Current clinical interventions include offloading braces, which mechanically realign the lower extremities to alleviate the pain experienced in the medial compartment of the knee joint. Though these braces have proven effective in pain management, studies have shown a significant decrease in knee ROM while using the brace. Concurrently, development of active exoskeletons for rehabilitative gait has increased within recent years in efforts to provide patients with a more effective intervention for dealing with KOA. Though some developed exoskeletons are promising in their efficacy of fostering gait therapy, these devices are heavy, tethered, difficult to control, unavailable to patients, or costly due to the number of complicated components used to manufacture the device. However, the idea that an active component can improve gait therapy for patients motivates this study. This study proposes the design of an adjustable lower extremity exoskeleton which features a single linear actuator adapted onto a commercially available offloading brace. This design hopes to provide patients with pain alleviation from the brace, while also actively driving the knee through flexion and extension. The design and execution of this exoskeleton was accomplished by 3D computer simulation, 3D CAD modeling, and rapid prototyping techniques. The exoskeleton features 3D printed, ABS plastic struts and supports to achieve successful adaptation of the linear actuator to the brace and an electromechanical system with a rechargeable operating capacity of 7 hours. Design validation was completed by running preliminary gait trials of neutral gait (without brace or exoskeleton), offloading brace, and exoskeleton to observe changes between the different gait scenarios. Results from this testing on a single subject show that there was an observed, significant decrease in average knee ROM in the offloading brace trials from the neutral trials and an observed, significant increase in average knee ROM in the exoskeleton trials when compared to the brace trials as hypothesized. Further evaluation must be completed on the clinical efficacy of this device with a larger, and clinically relevant sample size to assess knee ROM, pain while using the device, and overall comfort level. Further development of this design could focus on material assessment, cost analysis, and risk mitigation through failure mode analysis.

During the last few years, wearable technologies or body-worn assistive devices have become very popular within the occupational field. Among them, there are the so-called exoskeletons which have shown a promising potential in several areas ranging from medical care, military to, particularly during the last five years, industrial applications. In this sense, exoskeleton could represent a novel technical solution, with the potential to tackle the perennial problem of work-related musculoskeletal disorders. However, within the industrial field, there are still issues to be addressed such as exoskeletons’ long-term effects and adaptation to multiple tasks. This should be done through multiyear and extensive studies in real-life scenarios, to avoid that any issues pertaining to the individual, group or organizational level, could be overlooked. This thesis aimed to investigate factors that can promote or hinder the implementation of exoskeletons from a ‘‘whole system approach’’. To achieve this, first, a literature review was conducted in order to provide an overview of key findings from ongoing research about industrial exoskeletons. These key findings, which included current trends and knowledge gaps, formed the theoretical basis of this study. This was used in the development of an interview guide, which was used in semi-structured interviews. Thus, through qualitative interviewing, the key findings from the theoretical basis were further investigated. Moreover, once the data was gathered, the interviews were analyzed in depth and a content analysis of the interviews was systematically carried out, in order to find emerging “themes”. Furthermore, these ‘‘themes’’ were used to investigate underlying norms, contextual factors and challenges that exoskeletons may pose. Finally, the main ‘‘themes’’ and the key findings from the theoretical basis, were integrated into an intervention framework, the development of which was the secondary aim of this study. The new framework was designed aiming to guide policy makers, management, and personnel in planning, designing, and implementing ergonomic interventions through exoskeletons. The results of this study showed that safety, comfort, and fit are major factors in driving the adoption and acceptance of occupational exoskeletons. At the center of this suggested trifecta, there is productivity. However, when productivity is prioritized over the safety and the well-being of the workers, an “ergonomic pitfall” could be the consequence. It means the risk to add new constraints and challenges in the work environment, instead of reducing the physical workload and the muscle fatigue of the worker. Further, in terms of adoption barriers, the interviewees, in line with research in the field, stressed the importance to give enough time to the employees to familiarize themselves with the exoskeleton technology. In addition, since exoskeletons are introduced from the management side, it is key to effectively communicate the value proposition of exoskeletons, namely to protect worker’s health status rather than enable them to work at a higher pace or to handle heavier loads. In addition, based on the results of this study, practitioners should consider engaging in more inclusive dialogues with academia and policymakers to overcome the fragmentation of the exoskeletons’ market. Only by working in close collaboration with these stakeholders, and making full use of their experience and expertise, it can be possible in the near future to develop exoskeletons which are both aligned with workers’ and society needs, as well as with companies’ demands.

Alors que de nombreux exosquelettes destinés à la rééducation neuromotrice ont été développés ces dernières années, ces dispositifs n'ont pas encore permis de vrai progrès dans la prise en charge des patients cérébrolésés. Une des clés pour améliorer les faibles résultats thérapeutiques obtenus serait de constamment adapter la thérapie robotisée en fonction de l'évolution du patient et de sa récupération, en adaptant l'assistance fournie par le robot pour maximiser l'engagement du patient. L'objectif de cette thèse est donc de comprendre les processus d'adaptations réciproques dans un contexte d'interaction physique Homme-Exosquelette. Dans un premier temps nous avons donc développé un nouveau type de contrôleur adaptatif qui assiste le sujet "au besoin", en modulant l'assistance fournie; et évalué différent signaux pour piloter cette adaptation afin de suivre au mieux la récupération du patient. Dans un deuxième temps, nous avons étudié l'adaptation de sujets sains à l'application de champs de forces distribués par un exosquelette sur leur bras durant la réalisation de mouvements dans l'espace. En effet, lors d'une interaction physique homme-robot, le sujet adapte aussi son comportement aux contraintes exercées par le robot. D'importantes différences inter-individuelles ont été observées, avec une adaptation à la contrainte imposée chez seulement 21% des sujets, mais avec des effets à-posteriori persistants mesurés chez 85% d'entre eux; ainsi qu'une généralisation dans l'espace de ces effets et un transfert à des contextes différents (hors du robot). Ces premiers résultats devraient permettre à terme d'améliorer la rééducation neuromotrice robotisée. / While many robotic exoskeletons have been developed for stroke rehabilitation in recent years, there were not yet improvements to the traditional therapy. A key to unleash the potentiality of robotics is to adapt the assistance provided by the robot in order to maximize the subject engagement and effort, by having the robotic therapy evolving with the patient recovery. For this reason, we aim at better understanding the process of reciprocal adaptation in a context of physical Human-Robot Interaction (pHRI). We first developed a new adaptive controller, which assists the subject "as-needed", by regulating its interaction to maximize the human involvement. We further compared different signals driving this adaptation, to better following the functional recovery level of the patients. While the control is performed by the robot, the subject is also adapting his movements, and this adaptation has not yet been studied when dealing with 3D movements and exoskeletons. Therefore, we exposed human motions to distributed force fields, generated by the exoskeleton at the joint level, to produce specific inter-joint coordination and to analyse the effects of this exposition. With healthy participants, we observed important inter-individual difference, with adaptation to the fields in 21% of the participants, but post-effects and persisting retention of these in time in 85% of the subjects, together with spatial generalization, and, preliminarily, transfer of the effects outside of the exoskeleton context. This work towards understanding pHRI could provide insights on innovative ways to develop new controllers for improving stroke motor recovery with exoskeletons.

Les problèmes neurologiques dus aux AVC et aux lésions de la moelle épinière ainsi que la faiblesse des muscles squelettiques peuvent considérablement affecter les capacités motrices des personnes infirmes ou âgées. Les solutions traditionnellement utilisées pour l’assistance et le traitement de ces personnes dépendantes, sont relativement coûteuses; en termes de prise charge, elles impliquent, pour les aidants et les services de santé, des efforts humains et des moyens financiers importants. Dans ce cadre, la robotique apparaît comme une solution bien adaptée et prometteuse pour développer des systèmes d’assistance permettant d’améliorer l’autonomie des personnes dépendantes. Les exosquelettes des membres inférieurs sont des robots portables, destinés à être utilisés en tant que dispositifs d’aide à la mobilité pour augmenter les capacités motrices des sujets porteurs, ou comme auxiliaires de rééducation neuromusculaire. Ce domaine de recherche a fait l’objet, ces dernières années, d’un intérêt grandissant au sein de la communauté robotique. Du fait qu’un exosquelette est caractérisé par une interaction physique et cognitive directe avec son porteur, sa fonction principale est de fournir une assistance adaptée aux capacités sensorimotrices du sujet porteur. Il est, par conséquent, nécessaire de développer des stratégies de commande basées sur l’intention de mouvement du porteur. Du point de vue de l’exosquelette, les contacts physiques avec le sujet porteur ou l’environnement sont considérés comme des perturbations affectant la bonne réalisation des mouvements désirés du porteur. Ces perturbations doivent être également être prises en compte lors de la conception des stratégies de commande.Dans cette thèse, nous proposons trois stratégies de commandes assistives pour les exosquelettes des membres inférieurs. Deux modes d’assistance sont étudiés ici: le mode passif où le sujet dispose de capacités motrices très limitées et ne développe quasiment aucun effort, et le mode actif-aidé où le sujet possède certaines capacités motrices mais qui sont insuffisantes pour réaliser de manière autonome un mouvement désiré. Dans la première stratégie de commande, le sujet est supposé être en mode passif. Une commande robuste par modes glissants, basée sur un observateur non-linéaire de perturbations (Nonlinear Disturbance Observer (NDO)), est développée pour garantir un suivi précis des mouvements désirés de l’articulation du genou. Dans la deuxième stratégie de commande, nous proposons une structure de commande en impédance active non-linéaire où le sujet est supposé être en mode actif-aidé. Cette stratégie de commande assistive est utilisée pour assister le porteur dans la réalisation d’activités physiques mono-tâche. L’évaluation des performances de la structure proposée sont étudiées dans le cadre de deux activités: la flexion/extension du genou et le transfert assis-debout. Enfin, la troisième stratégie de commande proposée est une commande contextualisée pour assister le porteur dans ses activités de marche. Nous proposons une approche permettant de détecter le mode de marche dès le début d’un nouveau pas, en utilisant les caractéristiques cinématiques du porteur, à savoir la position et la vitesse des pieds lors de la marche. L’approche de détection du mode de marche rend possible la sélection des modèles cinématique et cinétique appropriés pour chaque mode. Différentes stratégies d’assistance sont développées: compensation partielle de la gravité, assistance basée impédance de type ressort/amortisseur virtuel et assistance de type impédance nulle. Ces stratégies sont combinées différemment selon le mode de marche estimé. Pour évaluer les performances des stratégies de commande proposées, deux prototypes d’exosquelettes des membres inférieurs ont été développés: l’exosquelette de l’articulation du genou EICOSI, et l’exosquelette des membres inférieurs E-ROWA / Neurological problems caused by stroke and spinal cord injury as well as the weakness of skeletal muscles may considerably affect the motor ability of the elderly and infirm. Traditional solutions of assistance and treatment for these dependent people are relatively costly; they generally need significant human efforts and financial resources from caregivers and national healthcare centers. In this context, robotics appears as a convenient and promising solution to develop assistive systems for improving the autonomy of dependent people. Lower limb exoskeletons are wearable robots that can be used as assistive devices for augmenting the wearer’s motor ability and/or improving the effectiveness of neuromuscular rehabilitation. Recently, they have attracted increasing interest in the robotics community. As lower limb exoskeletons exhibit close cognitive and physical interactions with the wearer, a fundamental function is to provide appropriate power assistance by taking into account the wearer’s sensor-motor ability. Consequently, it is of great importance to develop human intention based control strategies. Meanwhile, from the exoskeleton’s viewpoint, the physical contacts with the wearer and the environment are both considered disturbances affecting the accomplishment of the wearer’s desired movements. These disturbances should also be taken into account during the design of control strategies.In this thesis, we develop three assistive control strategies for lower limb exoskeletons. In the meantime, two modes of assistance are studied: the passive mode in which the wearer has very limited motor ability as well as the active-assisted mode in which the wearer has certain motor ability but that is insufficient to perform autonomously a desired physical movement. In the first control strategy, the wearer is assumed to be in passive mode. A robust sliding mode control approach is developed based on the use of a nonlinear disturbance observer, in order to guarantee accurate tracking performance of desired knee joint movements. In the second control strategy, we propose a human intention based nonlinear active impedance control structure, in which the wearer is in an active-assisted mode. This assistive strategy is used to assist the wearer in single-task physical activities, for instance, the knee joint flexion/ extension movement. We investigate the performance of the proposed control structure based on two case studies: knee-joint flexion/extension movements and sit-to-stand movements. Finally, the third control strategy is developed to assist the wearer during walking activities. We propose a new approach that is able to detect the gait mode at the early beginning of a new step using the kinematic features namely velocity and position of the wearer’s feet during walking. The proposed gait mode detection approach makes it possible to select appropriate kinematic and kinetic models for each gait mode. Different assistive strategies are developed: partial gravity compensation, virtual-spring/damper based impedance assistance and zero impedance assistance. These strategies are combined differently according to the estimated wearer’s gait mode. To evaluate the proposed control strategies, two lower limb exoskeleton prototypes are developed: a knee joint lower limb exoskeleton, called EICOSI, and a full lower limb exoskeleton, called E-ROWA