Author: James Lanphier Patton
Publisher:
ISBN:
Category : Human locomotion
Languages : en
Pages : 308

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Author: Marco Iosa
Publisher: Frontiers Media SA
ISBN: 2889196143
Category : Human locomotion
Languages : en
Pages : 192

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Book Description
Locomotion involves many different muscles and the need of controlling several degrees of freedom. Despite the Central Nervous System can finely control the contraction of individual muscles, emerging evidences indicate that strategies for the reduction of the complexity of movement and for compensating the sensorimotor delays may be adopted. Experimental evidences in animal and lately human model led to the concept of a central pattern generator (CPG) which suggests that circuitry within the distal part of CNS, i.e. spinal cord, can generate the basic locomotor patterns, even in the absence of sensory information. Different studies pointed out the role of CPG in the control of locomotion as well as others investigated the neuroplasticity of CPG allowing for gait recovery after spinal cord lesion. Literature was also focused on muscle synergies, i.e. the combination of (locomotor) functional modules, implemented in neuronal networks of the spinal cord, generating specific motor output by imposing a specific timing structure and appropriate weightings to muscle activations. Despite the great interest that this approach generated in the last years in the Scientific Community, large areas of investigations remain available for further improvement (e.g. the influence of afferent feedback and environmental constrains) for both experimental and simulated models. However, also supraspinal structures are involved during locomotion, and it has been shown that they are responsible for initiating and modifying the features of this basic rhythm, for stabilising the upright walking, and for coordinating movements in a dynamic changing environment. Furthermore, specific damages into spinal and supraspinal structures result in specific alterations of human locomotion, as evident in subjects with brain injuries such as stroke, brain trauma, or people with cerebral palsy, in people with death of dopaminergic neurons in the substantia nigra due to Parkinson’s disease, or in subjects with cerebellar dysfunctions, such as patients with ataxia. The role of cerebellum during locomotion has been shown to be related to coordination and adaptation of movements. Cerebellum is the structure of CNS where are conceivably located the internal models, that are neural representations miming meaningful aspects of our body, such as input/output characteristics of sensorimotor system. Internal model control has been shown to be at the basis of motor strategies for compensating delays or lacks in sensorimotor feedbacks, and some aspects of locomotion need predictive internal control, especially for improving gait dynamic stability, for avoiding obstacles or when sensory feedback is altered or lacking. Furthermore, despite internal model concepts are widespread in neuroscience and neurocognitive science, neurorehabilitation paid far too little attention to the potential role of internal model control on gait recovery. Many important scientists have contributed to this Research Topic with original studies, computational studies, and review articles focused on neural circuits and internal models involved in the control of human locomotion, aiming at understanding the role played in control of locomotion of different neural circuits located at brain, cerebellum, and spinal cord levels.

Author: Mohammad Sharif Shourijeh
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Musculoskeletal dynamics is a branch of biomechanics that takes advantage of interdisciplinary models to describe the relation between muscle actuators and the corresponding motions of the human body. Muscle forces play a principal role in musculoskeletal dynamics. Unfortunately, these forces cannot be measured non-invasively. Measuring surface EMGs as a non-invasive technique is recognized as a surrogate to invasive muscle force measurement; however, these signals do not reflect the muscle forces accurately. Instead of measurement, mathematical modelling of the musculoskeletal dynamics is a well established tool to simulate, predict and analyse human movements. Computer simulations have been used to estimate a variety of variables that are difficult or impossible to measure directly, such as joint reaction forces, muscle forces, metabolic energy consumption, and muscle recruitment patterns. Musculoskeletal dynamic simulations can be divided into two branches: inverse and forward dynamics. Inverse dynamics is the approach in which net joint moments and/or muscle forces are calculated given the measured or specified kinematics. It is the most popular simulation technique used to study human musculoskeletal dynamics. The major disadvantage of inverse dynamics is that it is not predictive and can rarely be used in the cause-effect interpretations. In contrast with inverse dynamics, forward dynamics can be used to determine the human body movement when it is driven by known muscle forces. The musculoskeletal system (MSS) is dynamically under-determinate, i.e., the number of muscles is more than the degrees of freedom (dof) of the system. This redundancy will lead to infinite solutions of muscle force sets, which implies that there are infinite ways of recruiting different muscles for a specific motion. Therefore, there needs to be an extra criterion in order to resolve this issue. Optimization has been widely used for solving the redundancy of the force-sharing problem. Optimization is considered as the missing consideration in the dynamics of the MSS such that, once appended to the under-determinate problem, \human-like" movements will be acquired. \Human-like" implies that the human body tends to minimize a criterion during a movement, e.g., muscle fatigue or metabolic energy. It is commonly accepted that using those criteria, within the optimization necessary in the forward dynamic simulations, leads to a reasonable representation of real human motions. In this thesis, optimal control and forward dynamic simulation of human musculoskeletal systems are targeted. Forward dynamics requires integration of the differential equations of motion of the system, which takes a considerable time, especially within an optimization framework. Therefore, computationally efficient models are required. Musculoskeletal models in this thesis are implemented in the symbolic multibody package MapleSim that uses Maple as the leverage. MapleSim generates the equations of motion governing a multibody system automatically using linear graph theory. These equations will be simplified and highly optimized for further simulations taking advantage of symbolic techniques in Maple. The output codes are the best form for the equations to be applied in optimization-based simulation fields, such as the research area of this thesis. The specific objectives of this thesis were to develop frameworks for such predictive simulations and validate the estimations. Simulating human gait motion is set as the end goal of this research. To successfully achieve that, several intermediate steps are taken prior to gait modelling. One big step was to choose an efficient strategy to solve the optimal control and muscle redundancy problems. The optimal control techniques are benchmarked on simpler models, such as forearm flexion/extension, to study the efficacy of the proposed approaches more easily. Another major step to modelling gait is to create a high-fidelity foot-ground contact model. The foot contact model in this thesis is based on a nonlinear volumetric approach, which is able to generate the experimental ground reaction forces more effectively than the previously used models. Although the proposed models and approaches showed strong potential and capability, there is still room for improvement in both modelling and validation aspects. These cutting-edge future works can be followed by any researcher working in the optimal control and forward dynamic modelling of human musculoskeletal systems.

Author: Juan Carlo Garcia Orden
Publisher: Springer Science & Business Media
ISBN: 1402056842
Category : Technology & Engineering
Languages : en
Pages : 297

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Book Description
The ECCOMAS Thematic Conference Multibody Dynamics 2005 was held in Madrid, representing the second edition of a series which began in Lisbon 2003. This book contains the revised and extended versions of selected conference communications, representing the state-of-the-art in the advances on computational multibody models, from the most abstract mathematical developments to practical engineering applications.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
The purpose of the Phase 1 research was to investigate and prototype methods to simulate realistic human activities utilizing physics based motions and limb trajectory control strategies. Under the Phase 1 work, researchers successfully simulated dynamic motion, impacts, and control schemes utilizing an advanced human model and 3D computer graphics program (Transom Jack). A comprehensive survey of potential control schemes was completed and documented, and the most promising control method was further developed. Potential applications for this work include dynamic simulation of human movement and locomotion under varying timing and loading conditions. The combination of 3D graphics, a realistic human biomechanical model, physics based motion, and dynamic control capabilities will allow assessment of energy expenditure, joint loading, and man equipment interface issues.

Author: Matthew Joseph Camilleri
Publisher:
ISBN:
Category :
Languages : en
Pages : 300

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Author: Olga Pätkau
Publisher:
ISBN:
Category :
Languages : en
Pages :

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In this thesis, two different control strategies are applied to the forward dynamic simulation of multibody systems in order to track a given reference motion. For this purpose, two different computational models are presented: a four-bar linkage model with one degree of freedom; and a two-dimensional human body model that consists of 12 segments with 14 degrees of freedom. The forward dynamic analysis of the two models is implemented using the matrix-R formulation and carried out by means of a variablestep integration solver. Furthermore, an analysis and comparison of different numerical integration methods are carried out. The joint forces and torques, which are applied to the multibody systems in order to drive their motion, are provided through an inverse dynamic analysis. In order to stabilize the simulation and to enable the tracking of a reference motion, two control methods are introduced: a proportional derivative control and a computed torque control using feedback linearization. The design of both control approaches is developed and applied to the forward dynamic simulation of both models. The system performance is evaluated by comparing the results with the reference motion. The reference human motion of a healthy subject was captured previously in a biomechanics laboratory. Moreover, the robustness of the computed torque control approach is analysed. In addition, environmental and social impacts of this thesis are outlined and an economical consideration is included.

Author: Paul Allard
Publisher: Champaign, IL : Human Kinetics
ISBN:
Category : Education
Languages : en
Pages : 392

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Book Description
Researchers, graduate students, and practitioners alike will benefit from this state-of-the-art reference. It's the first book to explain in a single volume the essential components of three-dimensional analysis of human movement. Readers will gain a fundamental understanding of methods and technology used to capture, reconstruct, and process 3-D data; concepts and techniques of mechanical and neuromuscular modeling, including robotics; and the application of 3-D analysis. The editors have brought together contributions from international experts to create a technical manual that demonstrates the possibilities and potential pitfalls of 3-D analysis of human movement. More than 140 tables, diagrams, and photos throughout the book illustrate essential content.

Author: Gary T. Yamaguchi
Publisher: Springer Science & Business Media
ISBN: 0387287507
Category : Technology & Engineering
Languages : en
Pages : 262

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Book Description
Dynamic Modeling of Musculoskeletal Motion introduces biomechanists to modern methods of modeling and analyzing dynamic biomechanical systems in three dimensions. Using vector kinematics, the reader is taught a systematic method which significantly reduces the complexity of working with multiple, moving limb segments in three dimensions. Operations which usually require the application of differential calculus are replaced by simple algebraic formulae. To derive dynamical equations of motion, a practical introduction to Kane's Method is given. Kane's Method builds upon the foundation of vector kinematics and represents one of the most exciting theoretical developments of the modern era. Together, these techniques enable biomechanists to decipher and model living systems with great realism, efficiency and accuracy. Interwoven with the theoretical presentation are chapters and examples which highlight the subtle differences between inanimate linkages and the biomechanical systems we seek to understand.

Author: Vladimir Medved
Publisher: CRC Press
ISBN: 142003698X
Category : Medical
Languages : en
Pages : 262

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Book Description
The importance of measurements for the proper assessment of human locomotion is increasingly being recognized. The fields of application encompass both healthy and pathological locomotion as encountered in rehabilitation medicine, orthopedics, kinesiology, sports medicine, and the like. Measurement of Human Locomotion provides an up-to-date des