151 research outputs found
Gait-Behavior Optimization Considering Arm Swing and Toe Mechanisms for Biped Robot on Rough Road
čęµ¦å·„ę„大å¦2019幓
Study of Biped Robot Walking Behavior: an Analysis of Toe Effect by Using the Gait Generation Method
čęµ¦å·„ę„大å¦201
Feedback Control of an Exoskeleton for Paraplegics: Toward Robustly Stable Hands-free Dynamic Walking
This manuscript presents control of a high-DOF fully actuated lower-limb
exoskeleton for paraplegic individuals. The key novelty is the ability for the
user to walk without the use of crutches or other external means of
stabilization. We harness the power of modern optimization techniques and
supervised machine learning to develop a smooth feedback control policy that
provides robust velocity regulation and perturbation rejection. Preliminary
evaluation of the stability and robustness of the proposed approach is
demonstrated through the Gazebo simulation environment. In addition,
preliminary experimental results with (complete) paraplegic individuals are
included for the previous version of the controller.Comment: Submitted to IEEE Control System Magazine. This version addresses
reviewers' concerns about the robustness of the algorithm and the motivation
for using such exoskeleton
LocomoĆ§Ć£o bĆpede adaptativa a partir de uma Ćŗnica demonstraĆ§Ć£o usando primitivas de movimento
Doutoramento em Engenharia EletrotĆ©cnicaEste trabalho aborda o problema de capacidade de imitaĆ§Ć£o da locomoĆ§Ć£o
humana atravĆ©s da utilizaĆ§Ć£o de trajetĆ³rias de baixo nĆvel codificadas com
primitivas de movimento e utilizĆ”-las para depois generalizar para novas
situaƧƵes, partindo apenas de uma demonstraĆ§Ć£o Ćŗnica. Assim, nesta linha de
pensamento, os principais objetivos deste trabalho sĆ£o dois: o primeiro Ć©
analisar, extrair e codificar demonstraƧƵes efetuadas por um humano, obtidas
por um sistema de captura de movimento de forma a modelar tarefas de
locomoĆ§Ć£o bĆpede. Contudo, esta transferĆŖncia nĆ£o estĆ” limitada Ć simples
reproduĆ§Ć£o desses movimentos, requerendo uma evoluĆ§Ć£o das capacidades
para adaptaĆ§Ć£o a novas situaƧƵes, assim como lidar com perturbaƧƵes
inesperadas. Assim, o segundo objetivo Ć© o desenvolvimento e avaliaĆ§Ć£o de
uma estrutura de controlo com capacidade de modelaĆ§Ć£o das aƧƵes, de tal
forma que a demonstraĆ§Ć£o Ćŗnica apreendida possa ser modificada para o robĆ“
se adaptar a diversas situaƧƵes, tendo em conta a sua dinĆ¢mica e o ambiente
onde estĆ” inserido.
A ideia por detrĆ”s desta abordagem Ć© resolver o problema da generalizaĆ§Ć£o a
partir de uma demonstraĆ§Ć£o Ćŗnica, combinando para isso duas estruturas
bƔsicas. A primeira consiste num sistema gerador de padrƵes baseado em
primitivas de movimento utilizando sistemas dinĆ¢micos (DS). Esta abordagem
de codificaĆ§Ć£o de movimentos possui propriedades desejĆ”veis que a torna ideal
para geraĆ§Ć£o de trajetĆ³rias, tais como a possibilidade de modificar determinados
parĆ¢metros em tempo real, tais como a amplitude ou a frequĆŖncia do ciclo do
movimento e robustez a pequenas perturbaƧƵes. A segunda estrutura, que estƔ
embebida na anterior, Ć© composta por um conjunto de osciladores acoplados
em fase que organizam as aƧƵes de unidades funcionais de forma coordenada.
MudanƧas em determinadas condiƧƵes, como o instante de contacto ou
impactos com o solo, levam a modelos com mĆŗltiplas fases. Assim, em vez de
forƧar o movimento do robƓ a situaƧƵes prƩ-determinadas de forma temporal, o
gerador de padrƵes de movimento proposto explora a transiĆ§Ć£o entre diferentes
fases que surgem da interaĆ§Ć£o do robĆ“ com o ambiente, despoletadas por
eventos sensoriais. A abordagem proposta Ć© testada numa estrutura de
simulaĆ§Ć£o dinĆ¢mica, sendo que vĆ”rias experiĆŖncias sĆ£o efetuadas para avaliar
os mƩtodos e o desempenho dos mesmos.This work addresses the problem of learning to imitate human locomotion actions
through low-level trajectories encoded with motion primitives and generalizing
them to new situations from a single demonstration. In this line of thought, the
main objectives of this work are twofold: The first is to analyze, extract and
encode human demonstrations taken from motion capture data in order to model
biped locomotion tasks. However, transferring motion skills from humans to
robots is not limited to the simple reproduction, but requires the evaluation of
their ability to adapt to new situations, as well as to deal with unexpected
disturbances. Therefore, the second objective is to develop and evaluate a
control framework for action shaping such that the single-demonstration can be
modulated to varying situations, taking into account the dynamics of the robot
and its environment.
The idea behind the approach is to address the problem of generalization from
a single-demonstration by combining two basic structures. The first structure is
a pattern generator system consisting of movement primitives learned and
modelled by dynamical systems (DS). This encoding approach possesses
desirable properties that make them well-suited for trajectory generation, namely
the possibility to change parameters online such as the amplitude and the
frequency of the limit cycle and the intrinsic robustness against small
perturbations. The second structure, which is embedded in the previous one,
consists of coupled phase oscillators that organize actions into functional
coordinated units. The changing contact conditions plus the associated impacts
with the ground lead to models with multiple phases. Instead of forcing the robotās
motion into a predefined fixed timing, the proposed pattern generator explores
transition between phases that emerge from the interaction of the robot system
with the environment, triggered by sensor-driven events. The proposed approach
is tested in a dynamics simulation framework and several experiments are
conducted to validate the methods and to assess the performance of a humanoid
robot
Climbing and Walking Robots
Nowadays robotics is one of the most dynamic fields of scientific researches. The shift of robotics researches from manufacturing to services applications is clear. During the last decades interest in studying climbing and walking robots has been increased. This increasing interest has been in many areas that most important ones of them are: mechanics, electronics, medical engineering, cybernetics, controls, and computers. Todayās climbing and walking robots are a combination of manipulative, perceptive, communicative, and cognitive abilities and they are capable of performing many tasks in industrial and non- industrial environments. Surveillance, planetary exploration, emergence rescue operations, reconnaissance, petrochemical applications, construction, entertainment, personal services, intervention in severe environments, transportation, medical and etc are some applications from a very diverse application fields of climbing and walking robots. By great progress in this area of robotics it is anticipated that next generation climbing and walking robots will enhance lives and will change the way the human works, thinks and makes decisions. This book presents the state of the art achievments, recent developments, applications and future challenges of climbing and walking robots. These are presented in 24 chapters by authors throughtot the world The book serves as a reference especially for the researchers who are interested in mobile robots. It also is useful for industrial engineers and graduate students in advanced study
Using Model-based Optimal Control for Conceptional Motion Generation for the Humannoid Robot HRP-2 14 and Design Investigations for Exo-Skeletons
The research field of bipedal locomotion has been active since a few decades now. At one hand, the legged locomotion principle comprises highly flexible and robust mobility for technical applications. At the other hand, a thorough technical understanding of bipedalism supports efforts of clinicians and engineers to help people, suffering from reduced locomotion capabilities caused by fatal incidents.
Since the technology enabled the construction of numerous robotic devices, among them: various humanoids, researchers started to investigate bipedalism by abstraction and adoption for technical applications. Findings from humanoid robotics are further exploited for the construction of devices for human performance augmentation and mobility support or gait rehabilitation, among them: orthosis and exo-skeletons.
Although this research continuously progresses, the motion capacities of humanoid robots still lack far behind those of humans in terms of forward velocity, robustness and appearance of the overall motion. Generally, it is claimed that the difference of performance between humans and robotics is not only due to the limiting characteristics of the employed technology, e.g. constructive lack of specific determinants of gait for bipedalism or dynamic limits of the actuation system, but as well to the adopted methods for motion generation and control.
For humanoid robotics, methods for motion generation are classified into optimization-based methods and those that employ heuristics, that are mostly distinguished based on the problem complexity (computation time) and the resulting dynamic error between the generated motion and the dynamics of the real robot. The implementation of the dynamic motion on the robotic platform is usually comprised with an on-line stabilizing control system. This control system must then identify and resolve instantaneously the dynamic error to maintain a continuously stable operation of the device. A large dynamic error and breach of the dynamic limits of the actuation system can quickly lead to a fatal destabilization of the device.
This work proposes a contribution to the model computation and the strategy of the problem formulation of direct multiple-shooting based optimal control (Bock et. al.) for dynamically stable optimization-based motion generation. The computation of the whole-body dynamic model inside the optimization relies either on forward or inverse dynamics approach. As the inverse dynamics approach has frequently been perceived as less resource intensive than the forward dynamics approach, a new generic algorithm for insufficiently constrained, under-actuated dynamic systems has been developed and thoroughly tested to comply with all numerical restrictions of the enveloping optimization algorithm.
Based on this contribution, various optimal control problems for the humanoid platform HRP-2 14 have been formulated to assess the influence of different biologically inspired optimization criteria on the final motion characteristics of walking motions. From thorough bibliographic researches a dynamically more accurate model was comprised, by taking into account the impact absorbing element in the ankle joint complex. Based on the experiences of the previous study, a problem formulation for the limiting case of, dynamically overstepping an obstacle of 20cm x 11cm (height x width) with only two steps, while maintaining its stable operation was accomplished. This is a new record for this platform.
In a further part, this work proposes an iterative comprehensive model-based optimal control approach for the conception of a lower limb exo-skeleton that respects the integrated nature of such a mechatronic device. In this contribution, a human effectively wearing such a lower limb exo-skeleton is modeled. The approach then substantiates all system components in an iterative procedure, based on the complete system model, effectively resolving all complex inter-dependencies between the different components of the system. The study in this work is conducted on an important benchmark motion, walking, of a healthy human being. From this study the limiting characteristics of the system are determined and substantial propositions to the realization of various system components are formulated
Bio-Inspired Robotics
Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensoryāmotor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field
Benchmarking Stability of Bipedal Locomotion Based on Individual Full Body Dynamics and Foot Placement StrategiesāApplication to Impaired and Unimpaired Walking
The principles underlying smooth and effortless human walking while maintaining stability as well as the ability to quickly respond to unexpected perturbations result from a plethora of well-balanced parameters, most of them yet to be determined. In this paper, we investigate criteria that may be useful for benchmarking stability properties of human walking. We perform dynamic reconstructions of human walking motions of unimpaired subjects and subjects walking with transfemoral prostheses from motion capture recordings using optimal control. We aim at revealing subject-specific strategies in applying dynamics in order to maintain steady gait considering irregularities such as deviating gait patterns or asymmetric body segment properties. We identify foot placement with respect to the Instantaneous Capture Point as the strategy globally applied by the subjects to obtain steady gait and propose the Residual Orbital Energy as a measure allowing for benchmarking human-like gait toward confident vs. cautious gait
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