Design of a wearable active ankle-foot orthosis for both sides

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Biomateriais, Reabilitação e Biomecânica)Portugal is the west European country with the highest rate of stroke-related mortality, being that, of those who suffer cerebrovascular accidents, 40% feature an impairment which can manifest itself through motor sequelae, namely drop foot. An ankle-foot orthosis is often recommended to passively accommodate these motor problems; however, active/powered exoskeletons are also a suitable solution for post-stroke patients. Due to the high complexity of the human ankle joint, one of the problems regarding these active devices is the misalignment occurring between the rehabilitation device and the human joint, which is a cause of parasitic forces, discomfort, and pain. The present master dissertation proposes the development of an adjustable wearable active ankle-foot orthosis that is able to tackle this misalignment issue concerning commercially available lower limb orthotic devices. This work is integrated on the SmartOs – Smart, Stand-alone Active Orthotic System – project that proposes an innovative robotic technology (a wearable mobile lab) oriented to gait rehabilitation. The conceptual design of a standard version of the SmartOs wearable active orthosis was initiated with the analysis of another ankle-foot orthosis – Exo-H2 (Technaid) – from which the necessary design changes were implemented, aiming at the improvement of the established device. In order to achieve a conceptual solution, both the practical knowledge of the Orthos XXI design team and several design methods were used to ensure the accomplishment of the defined requirements. The detailed design process of the standard SmartOs wearable active orthosis prototype is disclosed. With the purpose of validating the design, the critical components were simulated with the resources available in SolidWorks®, and the necessary CAD model’s adaptations were implemented to guarantee a reliable and safe design. The presented design is currently set for further production in Orthos XXI, followed by the mandatory mechanical tests.Portugal é o país da Europa ocidental com maior taxa de mortalidade por acidente vascular cerebral (AVC), sendo que, dos que sofrem acidentes vasculares cerebrais, 40% apresentam uma deficiência que pode manifestar-se por sequelas motoras, nomeadamente o pé pendente. Uma ortótese do tornozelo é recomendada frequentemente para acomodar passivamente esses problemas motores; no entanto, exoesqueletos ativos são também uma solução adequada para pacientes pós-AVC. Devido à alta complexidade da articulação do tornozelo humano, um dos problemas associados a esses dispositivos ativos é o desalinhamento que ocorre entre o dispositivo de reabilitação e a articulação humana, que é uma causa de forças parasitas, desconforto e dor. A presente dissertação de mestrado propõe o desenvolvimento de uma ortótese ativa do tornozelo ajustável e vestível, que seja capaz de resolver esse problema de desalinhamento relativo aos dispositivos ortóticos de membros inferiores disponíveis comercialmente. Este trabalho está integrado no projeto SmartOs - Smart, Stand-alone Active Orthotic System - projeto que propõe uma tecnologia robótica inovadora (wearable mobile lab) direcionada para a reabilitação da marcha. O projeto conceptual de uma versão padrão da ortótese ativa vestível do projeto SmartOs foi iniciado com a análise de outra ortótese do tornozelo – Exo-H2 (Technaid) - a partir da qual foram implementadas as alterações de projeto necessárias, visando o aprimoramento do dispositivo estabelecido. Para se chegar a uma solução conceptual, tanto o conhecimento prático da equipa de projeto da Orthos XXI como os diversos métodos de projeto foram utilizados para garantir o cumprimento dos requisitos definidos. O processo do desenho detalhado da versão padrão da ortótese ativa SmartOs será também divulgado. Com o objetivo de validar o projeto, os componentes críticos foram simulados com os recursos disponíveis no SolidWorks® e as adaptações necessárias do modelo CAD foram implementadas para garantir um projeto fidedigno e seguro. O projeto apresentado está atualmente em preparação para produção na empresa Orthos XXI, depois do qual se seguem os ensaios mecânicos obrigatórios

Hybrid Neuroprosthesis for Lower Limbs

Assistive technologies have been proposed for the locomotion of people with spinal cord injury (SCI). One of them is the neuroprosthesis that arouses the interest of developers and health professionals bearing in mind the beneficial effects promoted in people with SCI. Thus, the first session of this chapter presents the principles of human motility and the impact that spinal cord injury causes on a person’s mobility. The second session presents functional electrical stimulation as a solution for the immobility of paralyzed muscles. It explains the working principles of constituent modules and main stimulatory parameters. The third session introduces the concepts and characteristics of neural prosthesis hybridization. The last two sessions present and discuss examples of hybrid neuroprostheses. Such systems employ hybrid assistive lower limb strategies to evoke functional movements in people with SCI, associating the motor effects of active and/or passive orthoses to a functional electrical stimulation (FES) system. Examples of typical applications of FES in rehabilitation are discussed

Low obstacles avoidance for lower limb exoskeletons

Gli esoscheletri motorizzati per gli arti inferiori (LLEs) sono robot indossabili che permettono a soggetti con disabilità degli arti inferiori di camminare indipendentemente, e persino migliorare le prestazioni degli arti inferiori nel caso di soggetti sani. Nonostante i recenti sviluppi, l'uso di questa promettente tecnologia è relegato agli ambiti clinici e di ricerca; il suo utilizzo come strumento per camminare in modo indipendente in ambienti non controllati è ancora mancante. Il motivo principale di questa limitazione è dovuto alla mancanza di adattabilità degli LLE ai diversi ambienti che possono essere incontrati durante il cammino: la maggioranza degli LLE sfrutta traiettorie predefinite degli arti inferiori senza valutare l'ambiente circostante. Questo implica che ogni tipo di controllo addizionale è a carico dell'utente, e risulta in un sovraccarico fisico e cognitivo da parte di quest'ultimo. Questa tesi si pone l'obbiettivo di superare le limitazioni sopracitate, proponendo un approccio innovativo per aumentare l'autonomia degli LLE. In particolare, il metodo proposto ha lo scopo di stimare la traiettoria degli arti inferiori ottimale, così da poter superare in modo autonomo gli ostacoli bassi che potrebbero essere incontrati lungo il cammino. Tramite l'uso di una stereo camera unita ad un algoritmo di Computer Vision, l'ambiente viene percepito in modo da identificare il pavimento e gli ostacoli che potrebbero influenzare il cammino con l'obbiettivo di selezionare il punto d'appoggio ottimale per il piede. Successivamente, un algoritmo iterativo per la generazione della traiettoria del piede senza collisioni (CFFTG) permette di ottenere i dati necessari a calcolare la cinematica inversa dell'esoscheletro, ed infine gli angoli ai giunti ottenuti da quest'ultima vengono forniti ai controllori dei motori per effettuare il movimento desiderato. Test sperimentali in simulazione (basati su dati reali) sono stati eseguiti per valutare il comportamento dell'algoritmo di Computer Vision e del CFFTG, mostrando ottimi risultati in diversi scenari. Inoltre, le assunzioni su cui si basa la soluzione proposta permettono la sua compatibilità con la maggioranza degli esoscheletri commerciali e di ricerca attualmente disponibili. Credo che pensare agli esoscheletri come degli agenti semi autonomi, piuttosto che come dei dispositivi controllati unicamente dall'utente, rappresenti non solo un percorso che porterà alla simbiosi tra uomo ed esoscheletro, ma anche all'uso di questa tecnologia nella vita di tutti i giorni.Powered lower limb exoskeletons (LLEs) are innovative wearable robots that allow independent walking in people with severe gait impairments, or even to augment lower limb capabilities of able-bodied users. Despite the recent advancements, the use of this promising technology is still restricted to controlled research/clinical settings; uptake in real-life conditions as a device to promote user independence is still lacking. The main reason behind this limitation can be traced back to the lack adaptability of LLEs to the different walking conditions that may be encountered in real world settings: the majority of LLEs relies on predefined gait trajectories and is generally unaware of the environment in which gait occurs. This means that the control burden is entirely on the user, resulting in an increased physical and cognitive workload. This thesis aims at overcoming the aforementioned limitations by proposing a novel approach to enhance the autonomy of the LLEs. In particular, the proposed method has the purpose of estimating the optimal gait trajectory of the exoskeleton in order to autonomously avoid low obstacles on the ground. By using a depth camera coupled with Computer Vision software module, the environment is sensed to detect the ground plane and obstacles that might interfere with the forward motion, in order to predict the following foothold. Then, an iterative-based collision-free foot trajectory generator (CFFTG) algorithm is proposed to calculate the optimal foot motion and the joints’ angles to be sent to the exoskeleton low-level controllers. Experimental tests have been carried out in simulation to evaluate both the CV module and the CFFTG based on real data, showing successful performance in different scenarios. In addition, the assumptions that have been considered in this work make the proposed approach compatible with the majority of exoskeletons in research and on the market. I believe that re-thinking exoskeletons as semi-autonomous agents will represent not only the cornerstone to promote a more symbiotic human-exoskeleton interaction but may also pave the way for the use of this technology in the everyday life

Design and evaluation of a quasi-passive robotic knee brace : on the effects of parallel elasticity on human running

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2012.Cataloged from PDF version of thesis.Includes bibliographical references (p. 103-106).While the effects of series compliance on running biomechanics are documented, the effects of parallel compliance are known only for the simpler case of hopping. As many practical exoskeleton and orthosis designs act in parallel with the leg, it is desirable to understand the effects of such an intervention. Spring-like forces offer a natural choice of perturbation, as they are both biologically motivated and energetically inexpensive to implement. To this end, this thesis investigates the hypothesis that the addition of an external elastic element at the knee during the stance phase of running results in a reduction in knee extensor activation so that total joint quasi-stiffness is maintained. To test this, an exoskeleton is presented, consisting of a leaf spring in parallel with the knee joint and a clutch which engages this spring only during stance. The design of a custom interference clutch, made necessary by the need for high holding torque but low mass, is discussed in detail, as are problems of human attachment. The greater applicability of this clutch design to other problems in rehabilitation and augmentation is also addressed. Motion capture of four subjects is used to investigate the consequences of running with this exoskeleton. Leg stiffness is found to increase with distal mass, but no significant change in leg stiffness or total knee stiffness is observed due to the activation of the clutched parallel knee spring. However, preliminary evidence suggests differing responses between trained marathon runners, who appear to maintain biological knee torque, and recreational runners, who appear to maintain total knee torque. Such a relationship between degree of past training and effective utilization of an external force is suggestive of limitations on the applications of assistive devices.by Grant A. Elliott.Ph.D

Joint Trajectory Generation and High-level Control for Patient-tailored Robotic Gait Rehabilitation

This dissertation presents a group of novel methods for robot-based gait rehabilitation which were developed aiming to offer more individualized therapies based on the specific condition of each patient, as well as to improve the overall rehabilitation experience for both patient and therapist. A novel methodology for gait pattern generation is proposed, which offers estimated hip and knee joint trajectories corresponding to healthy walking, and allows the therapist to graphically adapt the reference trajectories in order to fit better the patient's needs and disabilities. Additionally, the motion controllers for the hip and knee joints, mobile platform, and pelvic mechanism of an over-ground gait rehabilitation robotic system are also presented, as well as some proposed methods for assist as needed therapy. Two robot-patient synchronization approaches are also included in this work, together with a novel algorithm for online hip trajectory adaptation developed to reduce obstructive forces applied to the patient during therapy with compliant robotic systems. Finally, a prototype graphical user interface for the therapist is also presented