A sEMG-driven Musculoskeletal Model to Control Exoskeleton Robot Used in Lower Extremity Rehabilitation

A control system framework of lower extremity rehabilitation exoskeleton robot is presented. It is based on the Neuro-Musculo-Skeletal biological model. Its core composition module, the motion intent parser part, mainly comprises of three distinct parts. The first part is signal acquisition of surface electromyography (sEMG) that is the summation of motor unit action potential (MUAP) starting from central nervous system (CNS).sEMG can be used to decode action intent of operator to make the patient actively participate in specific training .As another composition part, a muscle dynamics model that is comprised of activation and contraction dynamic model is developed. It is mainly used to calculate muscle force. The last part is the skeletal dynamic model that is simplified as a linked segment mechanics. Combined with muscle dynamic model, the joint torque exerted by internal muscles can be exported, which can be used to do a exoskeleton controller design. The developed control framework can make exoskeleton offer assistance to operators during rehabilitation by guiding motions on correct training rehabilitation trajectories, or give force support to be able to perform certain motions. Though the presentation is orientated towards the lower extremity exoskeleton, it is generic and can be applied to almost any part of the human body

Rehabilitation Engineering

Population ageing has major consequences and implications in all areas of our daily life as well as other important aspects, such as economic growth, savings, investment and consumption, labour markets, pensions, property and care from one generation to another. Additionally, health and related care, family composition and life-style, housing and migration are also affected. Given the rapid increase in the aging of the population and the further increase that is expected in the coming years, an important problem that has to be faced is the corresponding increase in chronic illness, disabilities, and loss of functional independence endemic to the elderly (WHO 2008). For this reason, novel methods of rehabilitation and care management are urgently needed. This book covers many rehabilitation support systems and robots developed for upper limbs, lower limbs as well as visually impaired condition. Other than upper limbs, the lower limb research works are also discussed like motorized foot rest for electric powered wheelchair and standing assistance device

Otimização muscle-in-the-loop em tempo real para reabilitação física com um exosqueleto ativo: uma mudança de paradigma

Assisting human locomotion with a wearable robotic orthosis is still quite challenging, largely due to the complexity of the neuromusculoskeletal system, the time-varying dynamics that accompany motor adaptation, and the uniqueness of every individual’s response to the assistance given by the robot. To this day, these devices have not met their well-known promise yet, mostly due to the fact that they are not perfectly suitable for the rehabilitation of neuropathologic patients. One of the main challenges hampering this goal still relies on the interface and co-dependency between the human and the machine. Nowadays, most commercial exoskeletons replay pre-defined gait patterns, whereas research exoskeletons are switching to controllers based on optimized torque profiles. In most cases, the dynamics of the human musculoskeletal system are still ignored and do not take into account the optimal conditions for inducing a positive modulation of neuromuscular activity. This is because both rehabilitation strategies are still emphasized on the macro level of the whole joint instead of focusing on the muscles’ dynamics and activity, which are the actual anatomical elements that may need to be rehabilitated. Strategies to keep the human in the loop of the exoskeleton’s control laws in real-time may help to overcome these challenges. The main purpose of the present dissertation is to make a paradigm shift in the approach on how the assistance that is given to a subject by an exoskeleton is modelled and controlled during physical rehabilitation. Therefore, in the scope of the present work, it was intended to design, concede, implement, and validate a real-time muscle-in-the-loop optimization model to find the best assistive support ratio that would induce optimal rehabilitation conditions to a specific group of impaired muscles while having a minimum impact on the other healthy muscles. The developed optimization model was implemented in the form of a plugin and was integrated on a neuromechanical model-based interface for driving a bilateral ankle exoskeleton. Experimental pilot tests evaluated the feasibility and effectiveness of the model. Results of the most significant pilots achieved EMG reductions up to 61 ± 3 % in Soleus and 41 ± 10 % in Gastrocnemius Lateralis. Moreover, results also demonstrated the efficiency of the optimization’s specific reduction on rehabilitation by looking into the muscular fatigue after each experiment. Finally, two parallel preliminary studies emerged from the pilots, which looked at muscle adaptation, after a new assistive condition had been applied, over time and at the effect of the lateral positioning of the exoskeleton’s actuators on the leg muscles.Auxiliar a locomoção humana com uma ortose robótica ainda é bastante desafiante, em grande parte devido à complexidade do sistema neuromusculoesquelético, à dinâmica variável no tempo que acompanha a adaptação motora e à singularidade da resposta de cada indivíduo à assistência dada pelo robô. Até hoje, está por cumprir a promessa inicial destes dispositivos, principalmente devido ao facto de não serem perfeitamente adequados para a reabilitação de pacientes neuropatológicos. Um dos principais desafios que dificultam esse objetivo foca-se ainda na interface e na co-dependência entre o ser humano e a máquina. Hoje em dia, a maioria dos exoesqueletos comerciais reproduz padrões de marcha predefinidos, enquanto que os exoesqueletos em investigação estão só agora a mudar para controladores com base em perfis de binário otimizados. Na maioria dos casos, a dinâmica do sistema musculoesquelético humano ainda é ignorada e não tem em consideração as condições ideais para induzir uma modulação positiva da atividade neuromuscular. Isso ocorre porque ambas as estratégias de reabilitação ainda são enfatizadas no nível macro de toda a articulação, em vez de se concentrar na dinâmica e atividade dos músculos, que são os elementos anatómicos que realmente precisam de ser reabilitados. Estratégias para manter o ser humano em loop nos comandos que controlam o exoesqueleto em tempo real podem ajudar a superar estes desafios. O principal objetivo desta dissertação é fazer uma mudança de paradigma na abordagem em como a assistência que é dada a um sujeito por um exosqueleto é modelada e controlada durante a reabilitação física. Portanto, no contexto do presente trabalho, pretendeu-se projetar, conceder, implementar e validar um modelo de otimização muscle-in-the-loop em tempo real para encontrar a melhor relação de suporte capaz de induzir as condições ideais de reabilitação para um grupo específico de músculos fragilizados, tendo um impacto mínimo nos outros músculos saudáveis. O modelo de otimização desenvolvido foi implementado na forma de um plugin e foi integrado numa interface baseada num modelo neuromecânico para o controlo de um exoesqueleto bilateral de tornozelo. Testes experimentais piloto avaliaram a viabilidade e a eficácia do modelo. Os resultados dos testes mais significativos demonstraram reduções de EMG de até 61 ± 3 % no Soleus e 41 ± 10 % no Gastrocnemius Lateral. Adicionalmente, os resultados demonstraram também a eficiência em reabilitação da redução específica no EMG devido à otimização tendo em conta a fadiga muscular após cada teste. Finalmente, dois estudos preliminares paralelos emergiram dos testes piloto, que analisaram a adaptação muscular após uma nova condição assistiva ter sido definida ao longo do tempo e o efeito do posicionamento lateral dos atuadores do exoesqueleto nos músculos da perna.Mestrado em Engenharia Biomédic

Non-linear actuators and simulation tools for rehabilitation devices

Mención Internacional en el título de doctorRehabilitation robotics is a field of research that investigates the applications of robotics in motor function therapy for recovering the motor control and motor capability. In general, this type of rehabilitation has been found effective in therapy for persons suffering motor disorders, especially due to stroke or spinal cord injuries. This type of devices generally are well tolerated by the patients also being a motivation in rehabilitation therapy. In the last years the rehabilitation robotics has become more popular, capturing the attention at various research centers. They focused on the development more effective devices in rehabilitation therapy, with a higher acceptance factor of patients tacking into account: the financial cost, weight and comfort of the device. Among the rehabilitation devices, an important category is represented by the rehabilitation exoskeletons, which in addition to the human skeletons help to protect and support the external human body. This became more popular between the rehabilitation devices due to the easily adapting with the dynamics of human body, possibility to use them such as wearable devices and low weight and dimensions which permit easy transportation. Nowadays, in the development of any robotic device the simulation tools play an important role due to their capacity to analyse the expected performance of the system designed prior to manufacture. In the development of the rehabilitation devices, the biomechanical software which is capable to simulate the behaviour interaction between the human body and the robotics devices, play an important role. This helps to choose suitable actuators for the rehabilitation device, to evaluate possible mechanical designs, and to analyse the necessary controls algorithms before being tested in real systems. This thesis presents a research proposing an alternative solution for the current systems of actuation on the exoskeletons for robotic rehabilitation. The proposed solution, has a direct impact, improving issues like device weight, noise, fabrication costs, size an patient comfort. In order to reach the desired results, a biomechanical software based on Biomechanics of Bodies (BoB) simulator where the behaviour of the human body and the rehabilitation device with his actuators can be analysed, was developed. In the context of the main objective of this research, a series of actuators have been analysed, including solutions between the non-linear actuation systems. Between these systems, two solutions have been analysed in detail: ultrasonic motors and Shape Memory Alloy material. Due to the force - weight characteristics of each device (in simulation with the human body), the Shape Memory Alloy material was chosen as principal actuator candidate for rehabilitation devices. The proposed control algorithm for the actuators based on Shape Memory Alloy, was tested over various configurations of actuators design and analysed in terms of energy eficiency, cooling deformation and movement. For the bioinspirated movements, such as the muscular group's biceps-triceps, a control algorithm capable to control two Shape Memory Alloy based actuators in antagonistic movement, has been developed. A segmented exoskeleton based on Shape Memory Alloy actuators for the upper limb evaluation and rehabilitation therapy was proposed to demosntrate the eligibility of the actuation system. This is divided in individual rehabilitation devices for the shoulder, elbow and wrist. The results of this research was tested and validated in the real elbow exoskeleton with two degrees of freedom developed during this thesis.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Eduardo Rocón de Lima.- Secretario: Concepción Alicia Monje Micharet.- Vocal: Martin Stoele

Application of multibody dynamics techniques to the analysis of human gait

La tesi que es presenta tracta l’estudi cinemàtic i dinàmic de la marxa humana mitjançant tècniques de dinàmica de sistemes multisòlid. Per a aquest propòsit, s’utilitzen dos models biomecànics: un model pla format per 11 segments i 14 graus de llibertat i un model tridimensional format per 18 segments i 57 graus de llibertat. La formulació dinàmica multisòlid ha estat desenvolupada en coordenades mixtes (naturals i relatives). La marxa de l’individu s’enregistra al laboratori utilitzant un sistema de captura del moviment mitjançant el qual s’obté la posició de cadascun dels 37 marcadors situats sobre el cos del subjecte. Les dades de posició es filtren utilitzant un algorisme basat en el singular spectrum analysis (SSA) i les coordenades naturals del model es calculen mitjançant relacions algebraiques entre les posicions dels marcadors. Posteriorment, un procés de consistència cinemàtica assegura les restriccions de sòlid rígid. El processament cinemàtic continua amb l’aproximació de les posicions mitjançant corbes B-spline d’on se n’obtenen, per derivació analítica, els valors de velocitat i acceleració. En una anàlisi dinàmica inversa de la marxa humana, s’acostumen a utilitzar com a dades d’entrada els paràmetres antropomètrics (geomètrics i inercials) dels segments, les dades cinemàtiques i les mesures de les plaques de força. En contraposició al que fan la majoria d’autors, en aquesta tesi, les mesures de les plaques de força no són utilitzades directament en l’anàlisi sinó que només s’usen per solucionar el problema del repartiment del torsor resultant de les forces de contacte durant la fase de doble suport. En aquesta fase, els dos peus es recolzen sobre el terra i les mesures cinemàtiques són insuficients per determinar el torsor en cada peu. El nou mètode de repartiment que es proposa (anomenat contact force plate sharing, CFP) és una de les aportacions de la tesi i destaca pel fet que permet determinar un conjunt de forces i moments dinàmicament consistents amb el model biomecànic, sense haver de modificar-ne les coordenades cinemàtiques ni afegir forces o moments residuals en algun dels segments. Encara dins l’àmbit de l’estudi dinàmic invers, s’ha analitzat la sensitivitat dels parells articulars a errors comesos en estimar els paràmetres antropomètrics, a errors que poden contenir les mesures de les plaques de força i a errors que es poden cometre en el processament cinemàtic de les mesures. L’estudi permet concloure que els resultats són molt sensibles als errors cinemàtics i a les forces mesurades per les plaques, sent els errors en els paràmetres antropomètrics menys influents. La tesi també presenta un nou model tridimensional de contacte peu-terra basat en el contacte esfera-pla i els seus paràmetres s’estimen mitjançant dos enfocaments diferents basats en tècniques d’optimització. El model s’utilitza com un mètode alternatiu per solucionar el problema del repartiment durant la fase de doble suport en dinàmica inversa, i també s’utilitza en simulacions de dinàmica directa per estimar les forces de contacte entre el model biomecànic i el seu entorn. En l’anàlisi dinàmica directa és necessària la implementació d’un controlador que està basat, en aquest cas, en el filtre de Kalman estès. Les contribucions més importants de la tesi, en el cas de l’anàlisi dinàmica inversa, es centren en el mètode CFP i en l’ús del model de contacte per solucionar el repartiment de forces de contacte en la fase de doble suport. Referent a l’anàlisi de la influència dels errors en les dades d’entrada del problema dinàmic invers, la modelització estadística dels errors conjuntament amb la pertorbació conjunta de més d’un paràmetre antropomètric a la vegada (mantenint constant l’alçada i el pes de la persona) és també una novetat. Per altra banda, el model de contacte presentat és també una contribució original. En l’estat de l’art actual no es troben models que usin dades reals capturades al laboratori i que a la vegada s’utilitzin per solucionar el problema de repartiment en el doble suport i per simular el contacte peu-terra en una anàlisi dinàmica directa. Finalment, el fet de desenvolupar un model que s’utilitzi tant per a l’anàlisi dinàmica directa com inversa és també una de les aportacions d’aquesta tesi. Tot i que les dues anàlisis, per separat, són temes de recerca comuns en l’àmbit de la Biomecànica, es troben a faltar estudis que comprovin la validesa dels resultats que se n’obtenen. En aquesta tesi, els resultats de la dinàmica inversa s’han utilitzat com a dades d’entrada de l’anàlisi dinàmica directa, el resultat de la qual (el moviment) ha pogut ser comparat amb el que s’obté de la captura del laboratori (entrada de la dinàmica inversa). D’aquesta manera, el cercle es tanca i es pot verificar la validesa tant dels models com dels resultats obtinguts.This thesis presents the kinematic and dynamic study of human motion by means of multibody system dynamics techniques. For this purpose, two biomechanical models are used: a 2D model formed by 11 segments with 14 degrees of freedom, and a 3D model that consists of 18 segments with 57 degrees of freedom. The movement of the subject is recorded in the laboratory using a motion capture system that provides the position along time of 37 markers attached on the body of the subject. Position data are filtered using an algorithm based on singular spectrum analysis (SSA) and the natural coordinates of the model are calculated using algebraic relations between the marker positions. Afterwards, a kinematic procedure ensures the kinematic consistency and the data processing continues with the approximation of the position histories using B-spline curves and obtaining, by analytical derivation, the velocity and acceleration values. This information is used as input of an inverse dynamic analysis. Differing to most published works, in this thesis the force plates measurements are not used directly as inputs of the analysis. When both feet contact the ground, kinematic measurements are insufficient to determine the individual wrench at each foot. One of the contributions of the thesis is a new strategy that is proposed to solve the this indeterminacy (called corrected force plate sharing, CFP) based on force plates data. Using this method, a set of two contact wrenches dynamically consistent with the movement are obtained with no need neither to add residual wrenches nor to modify the original motion. Also in the IDA field, the sensitivity of the joint torques to errors in the anthropometric parameters, in the force plate measurements and to errors committed during the kinematic data processing is studied. The analysis shows that the results are very sensitive to errors in force measurements and in the kinematic processing, being the errors in the body segment parameters less influential. A new 3D foot-ground contact model is presented and its parameters are estimated using optimization techniques. The model is used as an alternative method to solve the mentioned sharing problem during the double support phase and it is also used, in a forward dynamic analysis, to estimate the contact forces between the biomechanical model and its environment. The forward dynamic simulation requires the implementation of a controller that is based, in this case, on the extended Kalman filter. The most important contributions of the thesis in IDA are focused on the CFP sharing method and regarding the analysis of the influence of errors in input data on the inverse dynamics results, the statistical modelling of the uncertainties together with the perturbation of more than one parameter at same time (remaining height and weight as a constant parameters) is also new in the literature. Moreover, the presented foot-ground contact model is also original. In the current state of the art, there are no models that use real data captured in the laboratory to solve the contact wrench sharing problem during the double support phase. Furthermore, there are few studies simulating the foot-ground interaction in a forward dynamic analysis using a continuous foot-ground contact model. Finally, developing a model that is used for both forward and inverse dynamic analysis is a relevant aspect of the methodology used. Although the two approaches separately are common research topics in the field of biomechanics, a small number of studies prove the validity of the obtained results. In this thesis, the results of the inverse dynamics are used as input data for the forward dynamic analysis, and the results of the latter (the motion) have been compared with the motion capture in the laboratory (input of the inverse dynamics analysis). Thus, the circle has been closed which allows us to validate the accuracy of both the models and the obtained results

Doctor of Philosophy

dissertationMost humans have difficulty performing precision tasks, such as writing and painting, without additional physical support(s) to help steady or offload their arm's weight. To alleviate this problem, various passive and active devices have been developed. However, such devices often have a small workspace and lack scalable gravity compensation throughout the workspace and/or diversity in their applications. This dissertation describes the development of a Spatial Active Handrest (SAHR), a large-workspace manipulation aid, to offload the weight of the user's arm and increase user's accuracy over a large three-dimensional workspace. This device has four degrees-of-freedom and allows the user to perform dexterous tasks within a large workspace that matches the workspace of a human arm when performing daily tasks. Users can move this device to a desired position and orientation using force or position inputs, or a combination of both. The SAHR converts the given input(s) to desired velocit

Simulating a Flexible Robotic System based on Musculoskeletal Modeling

Humanoid robotics offers a unique research tool for understanding the human brain and body. The synthesis of human motion is a complex procedure that involves accurate reconstruction of movement sequences, modeling of musculoskeletal kinematics, dynamics and actuation, and characterization of reliable performance criteria. Many of these processes have much in common with the problems found in robotics research, with the recent advent of complex humanoid systems. This work presents the design and development of a new-generation bipedal robot. Its modeling and simulation has been realized by using an open-source software to create and analyze dynamic simulation of movement: OpenSim. Starting from a study by Fuben He, our model aims to be used as an innovative approach to the study of a such type of robot in which there are series elastic actuators represented by active and passive spring components in series with motors. It has provided of monoarticular and biarticular joint in a very similar manner to human musculoskeletal model. This thesis is only the starting point of a wide range of other possible future works: from the control structure completion and whole-body control application, to imitation learning and reinforcement learning for human locomotion, from motion test on at ground to motion test on rough ground, and obviously the transition from simulation to practice with a real elastic bipedal robot biologically-inspired that can move like a human bein