Bipedal robots offer a uniquely flexible platform capable of navigating complex, human-centric environments. This makes them ideally suited for a variety of missions, including disaster response and relief, emergency scenarios, or exoskeleton systems for individuals with disabilities. This, however, requires significant advances in humanoid locomotion and control, as they are still slow, unnatural, inefficient, and relatively unstable. The work of this dissertation the state of the art with the aim was of increasing the robustness and efficiency of these bipedal walking platforms. We present a series of control improvements to enable reliable, robust, natural bipedal locomotion that was validated on a variety of bipedal robots using both hardware and simulation experiments. A huge part of reliable walking involves maximizing the robot's control authority. We first present the development of a model predictive controller to both control the ground reaction forces and perform step adjustment for walking stabilization using a mixed-integer quadratic program. This represents the first model predictive controller to include step rotation in the optimization and leverage the capabilities of the time-varying divergent component of motion for navigating rough terrain. We also analyze the potential capabilities of model predictive controllers for the control of bipedal walking. As an alternative to standard trajectory optimization-based model predictive controls, we present several optimization-based control schemes that leverage more traditional bipedal walking control approaches by embedding a proportional feedback controller into a quadratic program. This controller is capable of combining multiple feedback mechanisms: ground reaction feedback (the "ankle strategy"), angular momentum (the "hip strategy"), swing foot speed up, and step adjustment. This allows the robot to effectively shift its weight, pitch its torso, and adjust its feet to retain balance, while considering environmental constraints, when available. To enable the robot to walk with straightened legs, we present a strategy that insures that the dynamic plans are kinematically and dynamically feasible to execute using straight legs. The effects of timing on dynamic plans are typically ignored, resulting in them potentially requiring significantly bending the legs during execution. This algorithm modifies the step timings to insure the plan can be executed without bending the legs beyond certain angle, while leaving the desired footsteps unmodified. To then achieve walking with straight legs we then presented a novel approach for indirectly controlling the center of mass height through the leg angles. This avoids complicated height planning techniques that are both computationally expensive and often not general enough to consider variable terrain by effectively biasing the solution of the whole-body controller towards using straighter legs. To incorporate the toe-off motion that is essential to both natural and straight leg walking, we also present a strategy for toe-off control that allows it to be an emergent behavior of the whole-body controller. The proposed approach was demonstrated through a series of simulation and experimental results on a variety of platforms. Model predictive control for step adjustment and rough terrain is illustrated in simulation, while the other step adjustment strategies and straight leg walking approaches are presented recovering from external disturbances and walking over a variety of terrains in hardware experiments. We discuss many of the practical considerations and limitations required when porting simulation-based controller development to hardware platforms. Using the presented approaches, we also demonstrated a important concept: using whole-body control frameworks, not every desired motion need be directly commanded. Many of these motions, such as toe-off, may simply be emergent behaviors that result by attempting to satisfy other objectives, such as desired reaction forces. We also showed that optimization is a very powerful tool for walking control, able to determine both stabilizing inputs and joint torques. / Ph. D. / Bipedal robots offer a uniquely flexible platform capable of navigating the complex, humancentric environment that we live in. This makes them ideally suited for a variety of missions, including disaster response and relief, emergency scenarios, or exoskeleton systems for individuals with disabilities. This, however, requires significant advances in humanoid locomotion and control, as they are still slow, unnatural, inefficient, and relatively unstable. The work of this dissertation aims to increase the robustness and efficiency of these bipedal walking platforms. To increase the overall stability of the robot while walking, we aimed to develop new control schemes that incorporate more of the same balance strategies used by people. These include the adjustment of ground reaction forces (the “ankle strategy”, shifting weight), angular momentum (the “hip strategy”, pitching the torso and windmilling the arms), swing foot speed up, and step adjustment. Using these approaches, the robot is able to walk much more stably. With the ability to use human-like control strategies, the next step is to develop appropriate methods to allow it to walk with straighter legs. Without correct step timing, it may be necessary at times to significantly bend the knees to take the specified step. We develop an approach to adjust the step timing to decrease the required knee bend of the robot. We then present an approach for indirectly controlling the robot height through the knee angles. This avoids traditional complicated height planning techniques that are both computationally hard and not general enough to consider complex terrain. To incorporate the toe-off motion that is essential to both natural and straight leg walking, we also present a new strategy for toe-off that allows it to emerge natural from the controller. We present the proposed approach through a series of simulation and experimental results on several robots and in several environments. We discuss many of the practical considerations and limitations required when porting simulation-based controller development to hardware platforms. Using the presented approaches, we also demonstrated an important concept: using whole-body control frameworks, not every desired motion need be directly commanded. Many of these motions, such as toe-off, may simply be emergent behaviors that result by attempting to satisfy other objectives, such as desired reaction forces. We also showed that optimization is a very powerful tool for walking control, able to determine both stabilizing inputs and joint torques.

The purpose of this study was to evaluate the functional effectiveness of a selection of women's walking shoes with particular attention being directed towards an assessment of specific shoe modifications which were included in a prototype model to theoretically reduce the undesirable characteristics associated with flexible shoes. Nine female subjects performed three trials for each of five shoe conditions. The prototype model decreased the encountered pressures and pressure integrals in the region of the second metatarsal-phalangeal joint. The use of the prototype shoe did not appear to unduly affect the gait of the subject.

This diploma thesis presents a new form of outdoor activity called Priessnitz Walking, which means a connection of nordic walking, cooling limbs in a cold water and a yoga breathing exercises. A physiological grounds of each of its parts has been explained in the theoretical part of the thesis as well as its benefits for older people. Next to this, the thesis concerns about a physiology of aging and the importance of regular physical activity in later life. Our clinical experiment investigated an effect of PW during six-week training programe in older women attending Cardio Club Motol. A significant change in cardiorespiratory function and a positive subjective evaluation of the participates has been shown. Besides, we have found Priessnitz walking to be a save kind of endurance training for older people. A long-term adherance, which we also focused on, was not confirmed. Powered by TCPDF (www.tcpdf.org)

The Ph.D. thesis is focused on using the reinforcement learning for four legged robot control. The main aim is to create an adaptive control system of the walking robot, which will be able to plan the walking gait through Q-learning algorithm. This aim is achieved using the design of the complex three layered architecture, which is based on the DEDS paradigm. The small set of elementary reactive behaviors forms the basis of proposed solution. The set of composite control laws is designed using simultaneous activations of these behaviors. Both types of controllers are able to operate on the plain terrain as well as on the rugged one. The model of all possible behaviors, that can be achieved using activations of mentioned controllers, is designed using an appropriate discretization of the continuous state space. This model is used by the Q-learning algorithm for finding the optimal strategies of robot control. The capabilities of the control unit are shown on solving three complex tasks: rotation of the robot, walking of the robot in the straight line and the walking on the inclined plane. These tasks are solved using the spatial dynamic simulations of the four legged robot with three degrees of freedom on each leg. Resulting walking gaits are evaluated using the quantitative standardized indicators. The video files, which show acting of elementary and composite controllers as well as the resulting walking gaits of the robot, are integral part of this thesis.

Author: Bc. Zuzana Vacková Title: Effect of Barefoot shoes on the footprint loading Objectives: The aim of this experiment is to evaluate if barefoot shoes affect the size of vertical component of contact force during walking on a smooth non- abrasive surface during normal conditions. Furthermore to find out which parameters can be used to monitor the degree of convergence foot behaviour during the stance phase of gait cycle with the barefoot and barefoot shoes. Methods: Seven probands (4 women, 3 men) aged 23 to 25 years participated at the study. The dynamic gait parameters (reaction forces from the pad) were measured using Kistler force plates in the extreme load laboratory at FTVS UK. Probands after introduction to the experiment went repeatedly over the power plate subjectively comfortable speed. The first measurement were done while walking in the barefoot type of shoes. The second measurement was barefoot walking. It was a one-time measurement. The obtained data were exported from BioWare® program into MS Excel. The final data processing was carried out in the MatLab program, where the necessary graphs of reaction forces and their evaluation were created. Results: All contact forces and their resultant and CoP coordinates were recorded during measurements. Only the vertical contact force...

Introdução. Os pacientes com DPOC apresentam capacidade de exercício reduzida e limitação funcional para realização de suas atividades diárias, impactando a qualidade de vida desses indivíduos. Além disso, foi demonstrado para esses indivíduos um maior risco de queda em comparação a indivíduos saudáveis da mesma idade. Contudo, não se sabe o papel da intolerância ao exercício em variáveis relacionadas a locomoção dos pacientes com DPOC como o custo de transporte (C), a velocidade autosselecionada (VAS) e a estabilidade dinâmica, que podem auxiliar na dimensão da influência dessa intolerância na vida diária desses indivíduos. Objetivo. O presente estudo se propôs a investigar o comportamento do C, da eficiência ventilatória, do conforto ventilatório e da estabilidade dinâmica em diferentes velocidades de caminhada de indivíduos com DPOC e comparar com indivíduos sem a doença, além de verificar a possível correspondência entre a VAS e a velocidade ótima. Materiais e Métodos. Onze participantes com DPOC fizeram parte desse estudo e foram comparados com onze controles pareados por sexo e idade. Eles foram primeiramente submetidos a um teste de exercício cardiopulmonar e, em um segundo momento, a uma avaliação do C. No protocolo submáximo, os participantes caminharam em cinco velocidades diferentes, sendo uma a VAS e outras quatro ±20% e ±40% da VAS. Além disso, os participantes foram avaliados em uma velocidade pré-determinada igual a todos (isovelocidade). Para todas as velocidades do protocolo os participantes caminharam durante cinco minutos. A partir dos valores de consumo de oxigênio (VO2) obtidos, foram calculados os valores de C. Simultaneamente, foram realizados registro de vídeos dos participantes para posterior análise cinemática da marcha. Foram calculados a frequência de passada (FP), o comprimento de passada (CP) e o coeficiente de variação (CoV) referente a FP, como medida da estabilidade dinâmica. Resultados. Não houve diferença do C dos pacientes com DPOC em relação aos controles, nem mesmo quando caminhavam em isovelocidade (p=0,623). Em todas as velocidades, os pacientes demonstraram menor eficiência ventilatória. A VAS dos pacientes foi menor, no entanto observou-se menor valor de C nas velocidades mais altas de caminhada. Apesar de os indivíduos com DPOC apresentarem menor FP e CP, a estabilidade dinâmica não demonstrou-se prejudicada na amostra estudada. Conclusão. Pacientes com DPOC caminham em velocidades reduzidas, em relação aos controles, especialmente devido à dispneia acompanhada de uma menor eficiência ventilatória. Embora o C seja semelhante ao de indivíduos saudáveis, os participantes com DPOC apresentaram o índice de reabilitação inferior, sugerindo, portanto, que o mecanismo pendular não esteja otimizado na VAS. Além de não encontrar diferenças na economia de caminhada, foram observadas alterações mínimas na estabilidade dinâmica da marcha destes indivíduos. Terapias que tratem do conforto ventilatório são potenciais ferramentas para a melhora da locomoção de pacientes com DPOC. / Background. Subjects with COPD present reduced exercise capacity and functional limitation to perform daily activities, which affects their quality of life. Furthermore, it is known that this population has increased risk of falls when compared to health subjects. However, it is still unknown the role of exercise intolerance on important variables to assess locomotion, as the cost of transport (C), the self-selected speed (VAS) and the dynamic stability, which might be able to help to dimension the exercise intolerance on their daily life. Objective. To investigate the behaviour of C ventilatory efficiency, ventilatory comfort and dynamic stability at different walking speeds in COPD subjects and compare them to healthy controls, as well as to verify the possible correspondence of VAS and optimal speed. Methods and Materials. 11 patients with COPD participated in this study and were matched with 11 control subjects in terms of gender and age. They underwent a cardiopulmonary exercise test and an evaluation of C. In this last evaluation, participants walked at five different walking speeds, among them VAS and the others ±20% and ±40% of the VAS. There was also a sixth predetermined walking speed (isovelocity). The participants walked during five minutes in each speed. The C values were calculated from the oxygen consumption (VO2) values. Simultaneously, the subjects were filmed for later analysis of gait kinematics. The stride frequency (FP), stride length (CP) and the coefficient of variation (CoV) from FP as a measure of dynamic stability, were calculated. Results. There was no significant difference between the C of participants with COPD and control subjects, not even when walking at isovelocity (p=0,623). For all speeds investigated, the ventilatory efficiency of COPD subjects was impaired when compared to healthy individuals. The participants in COPD group walked at a slower VAS, but the lower value of C was found during faster walking speeds. Even though the COPD group had less FP and shorter strides, their dynamic stability showed minimal impairment. Conclusion. The patients with COPD walked at a reduced walking speed when compared to control subjects, specially caused by dyspnea and a lower ventilatory efficiency. In spite of a similar C between groups, the COPD subjects presented an inferior rehabilitation index, therefore suggesting that their pendulum-like mechanism is not optimal at VAS. Furthermore, besides a walking economy with no differences between groups, minimal impairments were found for dynamic stability in COPD group. Therapies that treat ventilatory comfort are a potential tool to improve locomotion of COPD subjects.

This thesis is about control and balance stability of leggedlocomotion. It also presents a combination of tools that makesit easier to design controllers for large and complicated robotsystems. The thesis is divided into four parts. The first part studies and analyzes how walking machines arecontrolled, examining the literature of over twenty machinesbriefly, and six machines in detail. The goal is to understandhow the controllers work on a level below task and pathplanning, but above actuator control. Analysis and comparisonis done in terms of: i) generation of trunk motion; ii)maintaining balance; iii) generation of leg sequence andsupport patterns; and iv) reflexes. The next part describes WARP1, a four-legged walking robotplatform that has been builtwith the long term goal of walkingin rough terrain. First its modular structure (mechanics,electronics and control) is described, followed by someexperiments demonstrating basic performance. Finally themathematical modeling of the robot’s rigid body model isdescribed. This model is derived symbolically and is general,i.e. not restricted to WARP1. It is easily modified in case ofa different number of legs or joints. During the work with WARP1, tools for model derivation,control design and control implementation have been combined,interfaced and augmented in order to better support design andanalysis. These tools and methods are described in the thirdpart. The tools used to be difficult to combine, especially fora large and complicated system with many signals and parameterssuch as WARP1. Now, models derived symbolically in one tool areeasy to use in another tool for control design, simulation andfinally implementation, as well as for visualization andevaluation—thus going from equation to action. In the last part we go back to“equation”wherethese tools aid the study of balance stability when complianceis considered. It is shown that a legged robot in a“statically balanced”stance may actually beunstable. Furthermore, a criterion is derived that shows when aradially symmetric“statically balanced”stance on acompliant surface is stable. Similar analyses are performed fortwo controllers of legged robots, where it is the controllerthat cause the compliance. <b>Keywords</b>legged locomotion, control, balance, leggedmachines, legged robots, walking robots, walking machines,compliance, platform stability, symbolic modeling

<p>This thesis is about control and balance stability of leggedlocomotion. It also presents a combination of tools that makesit easier to design controllers for large and complicated robotsystems. The thesis is divided into four parts.</p><p>The first part studies and analyzes how walking machines arecontrolled, examining the literature of over twenty machinesbriefly, and six machines in detail. The goal is to understandhow the controllers work on a level below task and pathplanning, but above actuator control. Analysis and comparisonis done in terms of: i) generation of trunk motion; ii)maintaining balance; iii) generation of leg sequence andsupport patterns; and iv) reflexes.</p><p>The next part describes WARP1, a four-legged walking robotplatform that has been builtwith the long term goal of walkingin rough terrain. First its modular structure (mechanics,electronics and control) is described, followed by someexperiments demonstrating basic performance. Finally themathematical modeling of the robot’s rigid body model isdescribed. This model is derived symbolically and is general,i.e. not restricted to WARP1. It is easily modified in case ofa different number of legs or joints.</p><p>During the work with WARP1, tools for model derivation,control design and control implementation have been combined,interfaced and augmented in order to better support design andanalysis. These tools and methods are described in the thirdpart. The tools used to be difficult to combine, especially fora large and complicated system with many signals and parameterssuch as WARP1. Now, models derived symbolically in one tool areeasy to use in another tool for control design, simulation andfinally implementation, as well as for visualization andevaluation—thus going from equation to action.</p><p>In the last part we go back to“equation”wherethese tools aid the study of balance stability when complianceis considered. It is shown that a legged robot in a“statically balanced”stance may actually beunstable. Furthermore, a criterion is derived that shows when aradially symmetric“statically balanced”stance on acompliant surface is stable. Similar analyses are performed fortwo controllers of legged robots, where it is the controllerthat cause the compliance.</p><p><b>Keywords</b>legged locomotion, control, balance, leggedmachines, legged robots, walking robots, walking machines,compliance, platform stability, symbolic modeling</p>

Post-stroke hemiparesis usually leads to slow and asymmetric gait. Improving walking ability, specifically walking speed, is a common goal post-stroke. To develop effective post-stroke rehabilitation interventions, the underlying mechanisms that lead to changes in walking ability need to be fully understood. The overall goal of this research was to investigate the deficits that limit hemiparetic walking ability and understand the influence of post-stroke rehabilitation on walking ability in persons with post-stroke hemiparesis. Forward dynamics walking simulations of hemiparetic subjects (and speed-matched controls) with different levels of functional walking status were developed to investigate the relationships between individual muscle contributions to pre-swing forward propulsion, swing initiation and power generation subtasks and functional walking status. The analyses showed that muscle contributions to the walking subtasks are indeed related to functional walking status in the hemiparetic subjects. Increased contributions from the paretic leg muscles (i.e., plantarflexors and hip flexors) and reduced contributions from the non-paretic leg muscles (i.e., knee and hip extensors) to the walking subtasks were critical in obtaining higher functional walking status. Changes in individual muscle contributions to propulsion during rehabilitation were investigated by developing a large number of subject-specific forward dynamics simulations of hemiparetic subjects (with different levels of pre-training propulsion symmetry) walking pre- and post-locomotor training. Subjects with low paretic leg propulsion pre-training increased contributions to propulsion from both paretic leg (i.e., gastrocnemius) and non-paretic leg muscles (i.e., hamstrings) to improve walking speed during rehabilitation. Subjects with high paretic leg propulsion pre-training improved walking speed by increasing contributions to propulsion from the paretic leg ankle plantarflexors (i.e., soleus and gastrocnemius). This study revealed two primary strategies that hemiparetic subjects use to increase walking speed during rehabilitation. Experimental analyses were used to determine post-training biomechanical predictors of successful post-stroke rehabilitation, defined as performance over a 6-month follow-up period following rehabilitation. The strongest predictor of success was step length symmetry. Other potential predictors of success were identified including increased paretic leg hip flexor output in late paretic leg single-limb stance, increased paretic leg knee extensor output from mid to late paretic leg stance and increased paretic leg propulsion during pre-swing. / text

In recent years, there has been a noticeable rise in the use of walking in artistic practice. Artists explore, map, narrate, draw, follow and procrastinate through the use of pedestrianism. This rise in an artistic output that uses the walking body has coincided with a burgeoning literature in this field; a literature that, I argue, has yet to find its feet, frequently repeating, and so depoliticising, the dominant narrative that casts walking as a strategy of resistance to the high-speed technological demands of late capitalism. Beyond its role as emancipatory gesture, I show, walking is enmeshed in histories of gender, labour, punishment, power and protest; something that a focus on the art of the 1960s and ‘70s can help to uncover. Accordingly, this thesis seeks to place the recent rise of ‘walking art’ in a specific historical context, positing that the uses of walking by artists today find the key to their legitimation in moving image and performance work of the 1960s and ‘70s. Through chapters on the work of the Judson Dance Theater (1962-7) and Trisha Brown (early 1970s), Bruce Nauman’s studio films and videos (1967-9) and Agnes Martin’s only film Gabriel (1976), I argue that these artists used walking not only to deconstruct the mediums out of which they worked (dance, sculpture, painting), but also to negotiate the wider socio-political issues of the era, from protest marching and the moon landings to much more clandestine concerns such as surveillance and controlled viewership. These chapters reveal a walking body as supported by technology, subject to self-discipline, and negotiating a new relationship with the natural world. A final chapter on Janet Cardiff’s audio walks, which she first developed in the late 1990s, makes explicit a feminist problematic, as I ask where the female body resides in a long history of male walkers, and explore the broader question of how we write the history of ‘walking art’. Via Cardiff, I reflect on the place of the 1960s and ‘70s in our historical imagination today, arguing for a more uneasy reading of the art of these decades than we have previously been used to.