Os dispositivos robóticos bípedes tem um grande potencial de aplicações tanto comerciais como para pesquisa. Dentre as presentes lacunas existentes que limitam a sua aplicabilidade prática tem um destaque especial a incapacidade de realizar uma marcha estável, robusta, versátil e eficiente no ponto de vista energético. No presente estado da arte, existem três principais estratégias de abordagem para o problema e algumas de suas implementações obtiveram sucesso em satisfazer pelo menos um dos requisitos listados, porém nunca todos eles de forma simultânea. Dentro deste cenário, este trabalho se propôs desenvolver um novo critério de estabilidade para marcha bípede que possibilite marchas versáteis, robustas e eficientes. Inicialmente foi realizada uma avaliação de diversos simuladores de código aberto e o Simbody foi definido como o mais apropriado para ser utilizado no desenvolvimento das simulações dinâmicas realizadas nesta Tese. Uma toolbox de MATLAB para auxiliar nos cálculos cinemáticos e dinâmicos foi desenvolvida em conjunto com um módulo de Inter Process Communication para realizar a comunicação entre o MATLAB e o simulador. Foi realizado um estudo da marcha bípede, implementando e avaliando as estratégias do Zero Moment Point e do Limit CycleWalking. Este estudo resultou numa proposta de controlador não linear comutado para robôs em Ciclo Limite. Na procura de um novo critério de estabilidade foi abordado o estudo da marcha humana. Um procedimento para identificar os mecanismos que controlam a estabilidade da marcha humana é analisar a mesma sob perturbações, como tropeços, ou na ultrapassagem de obstáculos. Na literatura existiam bastantes referências sobre este tema, porém, faltou uma comparação da marcha humana sob diferentes condições de visão com a marcha de robôs que utilizam o ZMP. Foi descoberto que os seres humanos privados de visão têm uma estratégia de ultrapassagem de obstáculos semelhante a um robô com ZMP. A partir do conhecimento adquirido deste estudo é proposto e formulado um novo critério de estabilidade, o Step Viability, inspirado na marcha humana e no conceito de N-Step Capturability. O Step Viability baseia-se na definição de restrições que garantem a viabilidade de realizar passos futuros que garantam a convergência para um ponto fixo em tempo finito. O critério foi implementado utilizando-se uma otimização de trajetória multi-fase. Múltiplos testes foram realizados utilizando-se o modelo Compass Gait com diferentes parâmetros (distribuição de massa, torque máximo disponível), com diferentes inclinações e com vários padrões de marcha desejados (periódico, aumento uniforme e até aleatório não periódico). Adicionalmente o critério foi testado em um modelo de 5 segmentos, sintetizando uma marcha com variação tanto linear quanto aleatória. O critério foi bem-sucedido na geração de uma marcha estável em todos os testes e os resultados foram consistentes. A marcha pode ser sintetizada completamente desacoplada do critério de estabilidade, e o modelo renunciou automaticamente do padrão desenhado em favor da estabilidade. / Bipedal robots present a great potential for both commercial and research applications. However, there are some drawbacks that limit their applicability in the real world. The most prominent is the inability to perform a stable, robust, versatile and efficient gait. There are three main state of the art strategies to approach this problem. However, none of them has been successful in satisfying all the listed requirements simultaneously. In this context, this work conducted a study of bipedal gait, both in humans and robots, in order to implement and evaluate existing stability strategies. As a first step, an evaluation of several open source simulators was performed and Simbody was chosen as the most adequate for the dynamic simulations carried out in this Thesis. A MATLAB toolbox to help in the kinematic and dynamic calculations was developed in conjunction with a module of an Inter Process Communication to perform the communication between MATLAB and the simulator. A bipedal gait study was carried out, implementing and evaluating Zero Moment Point and Limit Cycle Walking strategies. This study resulted in a proposed nonlinear switched controller for Limit Cycle robots. In the search for a new stability criterion, human gait was analyzed. A procedure to identify the mechanisms controlling human gait stability is to analyze gait under disturbances such as stumbling or overcoming obstacles. In the literature, there were many references on this subject, however, there was a lack of comparison of the human gait under different vision conditions with the gait of robots that use the ZMP. It was found that vision-deprived humans have an obstacle crossing strategy similar to robots with ZMP. From the knowledge acquired from this study, it is proposed a novel stability criterion, the Step Viability, inspired on human gait and the N-Step Capturability concept. The Step Viability is based on the definition of constraints that ensure the viability of performing future steps that guarantee convergence to a fixed point in finite time. The criterion was implemented using a multi-phase trajectory optimization. Multiple tests were performed using the Compass Gait model with different parameters (mass distribution, maximum available torque), with different slopes and with several desired gait patterns (periodic, uniform increase and even random non-periodic). Additionally, the criterion was tested in a 5-links model, synthesizing a gait with both linear and random velocity variation. The criterion was successful on generating a stable gait in all the tests and the results presented consistent data. The gait could be designed completely uncoupled from the stability criterion, yet the model automatically renounced to follow the desired pattern in favor of maintaining stability.

In this dissertation, we describe the development of a humanoid bipedal robot that fully physically models the human walking system, including the biomechanics of the leg, the sensory feedback pathways available in the body, and the neural structure of the central pattern generator (CPG). Using two different models of the CPG, we explore several issues in the neurobiology and robotics literature, including the role of reflexes in locomotion, the role of load reception and positive force feedback in generating the gait, and the degree to which central or peripheral control plays in human walking. We show that the walking pattern can be generated by a combination of a half-center CPG and reflex interactions phase modulated by the CPG, and that load receptors in the muscles can play a substantial role in generating the gait, using positive force feedback. We compare the gait of the robot to human subjects and show that this architecture produces human-like stepping. Varying the degree of direct central control of lower limb muscles by the CPG, we show that the most human-like gait is generated with a relatively weak central control signal, which modulates reflex responses that generate most of the muscle activation. These results allow us to conceive of locomotion as a series of nested loops, with a central CPG or rhythm generator modulating lower level reflex interactions, while higher centers modulate the CPG. Since locomotion is a primary mechanism by which animals interact with the world, this research is relevant to artificial intelligence researchers. Recent understanding of cognition holds that minds are embodied, situated relative to a set of goals, and exist in a feedback loop of interaction with the environment. In our robot, we model the dynamics of the body, the neural architecture and the sensory feedback channels in a complete dynamical feedback loop, and show that the robot entrains to the the natural dynamics of the world. We propose the concept of nested loops with descending phase modulation as a conceptual paradigm for a more general understanding of nervous system organization.

La perte d'équilibre chez l'humain est un phénomène courant de la vie quotidienne. Plusieurs causes peuvent être identifiées, dont notamment des perturbations extérieures. Le scénario qui nous intéresse particulièrement est celui des passagers debout dans les transports en commun. La combinaison de plusieurs études accidentologiques fait ressortir un risque de blessure important pour ce type de situations, surtout pour des passagers debout et/ou âgées. Ces incidents en gendrent des blessures qui coûtent très cher au niveau du budget de la santé. La sécurité de ces passagers est donc à l’origine de ce travail. La perte et/ou le rattrapage d’équilibre est une question complexe qui met en jeu un ensemble de phénomènes tels que la perception de la perturbation, le traitement de l’information, la prise de décision et la mise en œuvre d’actions correctrices. Bien que les connaissances théoriques sur chacun de ces phénomènes soient avancées, il n’existe pas, à l’heure actuelle, de modèle global permettant de représenter la réaction des personnes dans des situations aussi concrètes et complexes que celle des passagers debout de transport en commun.Dans ce contexte, l’objectif principal de ce travail était de développer un outil de simulation pour évaluer les risques associés à la perte d’équilibre des passagers de transport en commun. / Loss of balance is a common phenomenon in our society resulting in injuries and even deaths each year. Among other common sources of destabilization such as slips or trips from an obstacle, the public transportation vehicles are a major source of balance-related injuries to its passengers. Accidental data suggest that the passenger casualties in these vehicles are common, especially to the standing and the elderly passengers, mainly due to the sudden acceleration/deceleration changes of the vehicle. These injuries as well as associated discomfort may discourage people from using these means of transport resulting in adverse economic and societal effects. In this context, the security of the standing passengers in these vehicles constitutes the main motivation of this work.Recovering balance from an external disturbance is a complex process which involves a set of phenomenon such as the perception of the disturbance, information processing, decision making and its implementation. Even though experimental research in the fields of biomechanics and neurosciences provide us with a fair understanding of these phenomena separately, we are unaware of a global model which represents the reaction of people in response to the external disturbances to their equilibrium. In this context, the objective of this work is to develop such a numerical tool which can be used for the assessment of risks associated with the loss of balance of the standing passengers. The essential feature of this tool is the prediction of the post-disturbance kinematics of the subjects depending upon the disturbance characteristics (magnitude, duration etc.) as well as the active recovery response. Another key feature is the representation of the reaction of different populations, especially the elderly, by integrating age effects in the model. For the development of the tool, mathematical modeling (e.g. simplified body representations) and control ideas are borrowed from the field of biped robotics which explicitly deals with the balance issues of bipeds. Further development is done in view of human balance recovery (BR) characteristics. The resulting BR tool shows reasonable predictive capacity of a human balance recovery response confirmed by the comparison of model predictions with experimental balance recovery data.

A análise da marcha humana é um dos principais recursos que podem ser utilizados no estudo e tratamento de patologias que envolvem o aparelho locomotor. O presente trabalho visa o projeto e a construção de um robô bípede antropomórfico para ser, juntamente com um laboratório de marcha, uma ferramenta de auxílio aos profissionais da saúde na análise da marcha humana. O robô construído é capaz de reproduzir, de uma forma assistida, padrões de marcha reais, cujos dados são previamente adquiridos por um laboratório de marcha. As características dimensionais e cinemáticas desse robô são semelhantes às de um corpo humano. Dessa forma, a escolha das dimensões dos membros do robô e das faixas de movimentação de suas articulações foi baseada em dados provenientes de corpos humanos. Além disso, para garantir uma semelhança ainda maior com o corpo humano, um mecanismo paralelo foi selecionado para ser o responsável pelos movimentos das articulações do tornozelo e do quadril. Um sistema de sensoriamento barato, baseado em sensores de inclinação e de contato, foi desenvolvido para avaliar a reprodução da marcha humana por parte do robô. Agora, para acionar o robô, servo motores controlados por sinais PWM foram utilizados. Esse trabalho também apresenta o desenvolvimento de um modelo dinâmico tridimensional do robô que considera a sua interação com o solo. / The analysis of the human gait is one of the main resources that can be used in studies and treatment of pathologies which involve the locomotor system. The goal of this research is to design and to build an anthropomorphic biped robot to be used as a tool that could help health professionals to study the human gait. Once built, the robot can reproduce in an assisted way, real gait patterns based on datas that were previously acquired by a gait laboratory. The dimensionals and kinematics traits of this robot are alike to the human body. Therefore the choice of the limb dimensions from the robot and the bustle ranges of its articulations were based on datas originated in human bodies. Beyond this and to guarantee a great similarity to the human body a parallel mechanism was selected to be the responsible for the articulations movements of the ankle and hip. A cheap sensor system based on tilt and contact sensors was developed to evaluate the reproduction of the human gait by the robot. To operate the robot servo-motors controlled by PWM signals were used. This study also presents the development of a three-dimensional dynamic model of the robot that considers its interaction with the ground.

No description available.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第18946号 / 工博第3988号 / 新制||工||1614 / 31897 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 泉田 啓, 教授 藤本 健治, 教授 松野 文俊 / 学位規則第4条第1項該当

The field of autonomous walking robots has been dominated by the trajectory-control approach, which rigidly dictates joint angle trajectories at the expense of both energy efficiency and stability, and the passive dynamics approach, which uses no actuators, relying instead on natural mechanical dynamics as the sole source of control. Although the passive dynamics approach is energy efficient, it lacks the ability to modify gait or adapt to disturbances. Recently, minimally actuated walkers, or dynamic walkers, have been developed that use hip or ankle actuators---knees are always passive---to regulate mechanical energy variations through the timely application of joint torque pulses. Despite the improvement minimal actuation has provided, energy efficiency remains below target values and perturbation rejection capability (i.e., stability) remains poor. In this dissertation, we develop and analyze a simplified robotic system to assess biologically inspired methods of improving energy efficiency and stability in dynamic walkers. Our system consists of a planar, dynamically swinging leg with hip and knee actuation. Neurally inspired, nonlinear oscillators provide closed-loop control without overriding the leg's natural dynamics. We first model the passive stiffness of muscles by applying stiffness components to the joints of a hip-actuated swinging leg. We then assess the effect active knee control has on unperturbed and perturbed leg swinging. Our results indicate that passive joint stiffness improves energy efficiency by reducing the actuator work required to counter gravitational torque and by promoting kinetic energy transfer between the shank and thigh. We also found that active knee control 1) is detrimental to unperturbed leg swinging because it negatively affects energy efficiency while producing minimal performance improvement and 2) is beneficial during perturbed swinging because the perturbation rejection improvement outweighs the reduction in energy efficiency. By analyzing the effects of applying passive joint stiffness and active knee control to dynamic walkers, this work helps to bridge the gap between the performance capability of trajectory-control robots and the energy-efficiency of passive dynamic robots.

A análise da marcha humana é um dos principais recursos que podem ser utilizados no estudo e tratamento de patologias que envolvem o aparelho locomotor. O presente trabalho visa o projeto e a construção de um robô bípede antropomórfico para ser, juntamente com um laboratório de marcha, uma ferramenta de auxílio aos profissionais da saúde na análise da marcha humana. O robô construído é capaz de reproduzir, de uma forma assistida, padrões de marcha reais, cujos dados são previamente adquiridos por um laboratório de marcha. As características dimensionais e cinemáticas desse robô são semelhantes às de um corpo humano. Dessa forma, a escolha das dimensões dos membros do robô e das faixas de movimentação de suas articulações foi baseada em dados provenientes de corpos humanos. Além disso, para garantir uma semelhança ainda maior com o corpo humano, um mecanismo paralelo foi selecionado para ser o responsável pelos movimentos das articulações do tornozelo e do quadril. Um sistema de sensoriamento barato, baseado em sensores de inclinação e de contato, foi desenvolvido para avaliar a reprodução da marcha humana por parte do robô. Agora, para acionar o robô, servo motores controlados por sinais PWM foram utilizados. Esse trabalho também apresenta o desenvolvimento de um modelo dinâmico tridimensional do robô que considera a sua interação com o solo. / The analysis of the human gait is one of the main resources that can be used in studies and treatment of pathologies which involve the locomotor system. The goal of this research is to design and to build an anthropomorphic biped robot to be used as a tool that could help health professionals to study the human gait. Once built, the robot can reproduce in an assisted way, real gait patterns based on datas that were previously acquired by a gait laboratory. The dimensionals and kinematics traits of this robot are alike to the human body. Therefore the choice of the limb dimensions from the robot and the bustle ranges of its articulations were based on datas originated in human bodies. Beyond this and to guarantee a great similarity to the human body a parallel mechanism was selected to be the responsible for the articulations movements of the ankle and hip. A cheap sensor system based on tilt and contact sensors was developed to evaluate the reproduction of the human gait by the robot. To operate the robot servo-motors controlled by PWM signals were used. This study also presents the development of a three-dimensional dynamic model of the robot that considers its interaction with the ground.

Orientador: Douglas Eduardo Zampieri / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-04T03:12:52Z (GMT). No. of bitstreams: 1 Goncalves_JoaoBosco_D.pdf: 9689870 bytes, checksum: db2fb279a1080765ab5bddf9068a356d (MD5) Previous issue date: 2004 / Resumo: Este trabalho concebeu um robô bípede composto por uma sucessão de elos rígidos interconectados por 12 articulações rotativas, permitindo movimentos tridimensionais. O robô bípede é constituído por dois subsistemas: tronco e membros inferiores. A modelagem matemática foi realizada em separado para cada um dos subsistemas, que são integrados pelas forças reativas de vínculo. Nossa proposta permite ao robô bípede executar a andadura dinâmica utilizando o tronco para fornecer o balanço dinâmico (estabilidade postural). De forma inédita, foi desenvolvido um gerador automático de trajetória para o tronco que processa as informações de posições e acelerações impostas aos membros inferiores, dotando o robô bípede de reflexos. Foi desenvolvido um gerador de marcha que utiliza a capacidade do robô bípede de executar movimentos tridimensionais, implicando andadura dinamicamente estável sem a efetiva utilização do tronco. O gerador automático de trajetória para o tronco entra em ação se a marcha gerada não mantiver o balanço dinâmico, restabelecendo uma marcha estável. Foi projetado um sistema de controle adaptativo por modelo de referência que utiliza redes neurais artificiais. A avaliação de estabilidade é feita segundo o critério de Lyapunov. O sistema de controle e o gerador automático de trajetórias para o tronco são integrados, compondo os mecanismos adaptativos desenvolvidos para solucionar o modo de andar dinâmico / Abstract: The main objective of this work is to project a biped robot machine with a trunk. The mathematical model was realized by considering two sub-systems: the legs and the trunk. The trajectories of the trunk are planned to compensate torques inherent to the dynamic gait, permitting to preserve the dynamic balance of the biped robot. An automatic generator of trajectory for the trunk was developed that processes the infonnation of positions and accelerations imposed to the legs. A gait generator was developed that uses the capacity of the biped robot to execute three-dimensional movements, causing a steady dynamic gait without the effective use of the trunk. The automatic generator of trajectory for the trunk actuates, if the generated do not keep the dynamic balance, reestablishing he steady dynamic gait. A neural network reference model for the adaptive control was projected, which utilizes an RBF neural network and a stability evaluation is based on the criterion of Lyapunov. The system of control and the automatic generator of trajectories for the trunk are integrated, composing the adaptive mechanisms developed to solve the way of dynamic walking / Doutorado / Mecanica dos Sólidos e Projeto Mecanico / Doutor em Engenharia Mecânica

Rhythmic motion is ubiquitous in nature and technology. Various motions of organisms like the heart beating and walking require stable periodic execution. The stability of the rhythmic execution of human movement can be altered by neurological or orthopedic impairment. In robotics, successful development of legged robots heavily depends on the stability of the controlled limit-cycle. An accurate measure of the stability of rhythmic execution is critical to the diagnosis of several performed tasks like walking in human locomotion. Floquet multipliers have been widely used to assess the stability of a periodic motion. The conventional approach to extract the Floquet multipliers from actual data depends on the least squares method. We devise a new way to measure the Floquet multipliers with reduced bias and estimate orbital stability more accurately. We show that the conventional measure of the orbital stability has bias in the presence of noise, which is inevitable in every experiment and observation. Compared with previous method, the new method substantially reduces the bias, providing acceptable estimate of the orbital stability with fewer cycles even with different noise distributions or higher or lower noise levels. The new method can provide an unbiased estimate of orbital stability within a reasonably small number of cycles. This is important for experiments with human subjects or clinical evaluation of patients that require effective assessment of locomotor stability in planning rehabilitation programs. / Graduate / 2018-11-22