scholarly journals Hand posture comparison in Synergy Space

2017 ◽  
Author(s):  
Nayan Bhatt ◽  
Varadhan SKM
Keyword(s):  
Degrees Of Freedom ◽  
Joint Angle ◽  
Similarity Index ◽  
Movement Control ◽  
Human Movement ◽  
Hand Posture ◽  
Joint Angles ◽  
Angle Space ◽  
The Central Nervous System ◽  
Kinematic Transformation

In studies of human movement control, an important question is how the central nervous system (CNS) controls movements in the presence of a large number of degrees of freedom (DoFs) at all levels of the control architecture. It is known that CNS groups the multiple DoFs into representative functional units also called synergies for simplification of the task. Hence, comparing two different hand postures in the synergy space, rather than joint angle space may provide insightful information about efforts needed (in terms of synergy components) to transform from one hand posture to another hand posture. Working with synergy space may also provide information about how CNS deals with system with multiple DoFs. We developed an index called posture similarity index (PSI) which measures the similarity of two postures by projecting hand posture from the joint angles into the synergy space. A large value of PSI represents high similarity between postures whereas a lower value represents less similarity between postures. This index uses principle of synergies and nicely captures effort required for kinematic transformation. Using this index as a feature, possible set of representative postures can be identified. The other hand postures can be derived from a possible set of representative postures with relatively less efforts for kinematic transformation.

scholarly journals Perspective on musculoskeletal modelling and predictive simulations of human movement to assess the neuromechanics of gait

2021 ◽  
Vol 288 (1946) ◽  
pp. 20202432
Author(s):  
Friedl De Groote ◽  
Antoine Falisse
Keyword(s):  
Musculoskeletal System ◽  
Degrees Of Freedom ◽  
Human Movement ◽  
Human Gait ◽  
Complex Interactions ◽  
Musculoskeletal Models ◽  
The Central Nervous System ◽  
Fundamental Insight ◽  
Insight Into ◽  
Predictive Simulations

Locomotion results from complex interactions between the central nervous system and the musculoskeletal system with its many degrees of freedom and muscles. Gaining insight into how the properties of each subsystem shape human gait is challenging as experimental methods to manipulate and assess isolated subsystems are limited. Simulations that predict movement patterns based on a mathematical model of the neuro-musculoskeletal system without relying on experimental data can reveal principles of locomotion by elucidating cause–effect relationships. New computational approaches have enabled the use of such predictive simulations with complex neuro-musculoskeletal models. Here, we review recent advances in predictive simulations of human movement and how those simulations have been used to deepen our knowledge about the neuromechanics of gait. In addition, we give a perspective on challenges towards using predictive simulations to gain new fundamental insight into motor control of gait, and to help design personalized treatments in patients with neurological disorders and assistive devices that improve gait performance. Such applications will require more detailed neuro-musculoskeletal models and simulation approaches that take uncertainty into account, tools to efficiently personalize those models, and validation studies to demonstrate the ability of simulations to predict gait in novel circumstances.

scholarly journals Prediction of Limb Joint Angles Based on Multi-Source Signals by GS-GRNN for Exoskeleton Wearer

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 1104
Author(s):  
Hualong Xie ◽  
Guanchao Li ◽  
Xiaofei Zhao ◽  
Fei Li
Keyword(s):  
Neural Network ◽  
Lower Limb ◽  
Prediction Accuracy ◽  
Joint Angle ◽  
Golden Section ◽  
Human Movement ◽  
Lower Limbs ◽  
General Regression Neural Network ◽  
Joint Angles ◽  
Prediction Result

To enable exoskeleton wearers to walk on level ground, estimation of lower limb movement is particularly indispensable. In fact, it allows the exoskeleton to follow the human movement in real time. In this paper, the general regression neural network optimized by golden section algorithm (GS-GRNN) is used to realize prediction of the human lower limb joint angle. The human body hip joint angle and the surface electromyographic (sEMG) signals of the thigh muscles are taken as the inputs of a neural network to predict joint angles of lower limbs. To improve the prediction accuracy in different gait phases, the plantar pressure signals are also added into the input. After that, the error between the prediction result and the actual data decreases significantly. Finally, compared with the prediction result of the BP neural network, GRNN shows splendid prediction performance for its less processing time and higher prediction accuracy.

A numerically stable algorithm for analytic inverse kinematics of 7-DoF S-R-S manipulators with joint limit avoidance

2021 ◽  
pp. 1-15
Author(s):  
Junchen Wang ◽  
Chunheng Lu ◽  
Yinghao Zhang ◽  
Zhen Sun ◽  
Yu Shen
Keyword(s):  
Inverse Kinematics ◽  
Joint Angle ◽  
State Of The Art ◽  
Joint Angles ◽  
Stable Algorithm ◽  
Angle Space ◽  
Joint Limits ◽  
Self Motion ◽  
Configuration Control ◽  
Joint Limit

Abstract This paper presents a numerically stable algorithm for analytic inverse kinematics of 7-DoF S-R-S manipulators with joint limit avoidance. The arm angle is used to represent the self-motion manifold within a global arm configuration. The joint limits are analytically mapped to the arm angle space for joint limit avoidance. To profile the relation between the joint angle and arm angle, it is critical to characterize the singular arm angle for each joint. In the-state-of-the art methods, the existence of the singular arm angle is triggered by comparing a discriminant with zero given a threshold. We will show this leads to numerical issues since the threshold is inconsistent among different target poses, leading to incorrect range of the arm angle. These issues are overcome by associating indeterminate joint angles of tangent joints with angles of 0 or pi of cosine joints, rather than using an independent threshold for each joint. The closed-form algorithm in C++ code to perform numerically stable inverse kinematics of 7-DoF S-R-S manipulators with global arm configuration control and joint limit avoidance is also given.

A Nonlinear Dynamics Approach to Human Movement

2004 ◽  
Vol 20 (4) ◽  
pp. 396-420 ◽  
Author(s):  
Richard E.A. Van Emmerik ◽  
Michael T. Rosenstein ◽  
William J. McDermott ◽  
Joseph Hamill
Keyword(s):  
Nonlinear Dynamics ◽  
Dynamical Systems ◽  
Degrees Of Freedom ◽  
Movement Control ◽  
Human Movement ◽  
Human Locomotion ◽  
Nonlinear Dynamical ◽  
Control Structures ◽  
Systems Approaches ◽  
Level Of Understanding

Nonlinear dynamics and dynamical systems approaches and methodologies are increasingly being implemented in biomechanics and human movement research. Based on the early insights of Nicolai Bernstein (1967), a significantly different outlook on the movement control “problem” over the last few decades has emerged. From a focus on relatively simple movements has arisen a research focus with the primary goal to study movement in context, allowing the complexity of patterns to emerge. The approach taken is that the control of multiple degrees-of-freedom systems is not necessarily more difficult or complex than that of systems only comprising a few degrees of freedom. Complex patterns and dynamics might not require complex control structures. In this paper we present a tutorial overview of the mathematical underpinnings of nonlinear dynamics and some of its basic analysis tools. This should provide the reader with a basic level of understanding about the mathematical principles and concepts underlying pattern stability and change. This will be followed by an overview of dynamical systems approaches in the study of human movement. Finally, we discuss recent progress in the application of nonlinear dynamical techniques to the study of human locomotion, with particular focus on relative phase techniques for the assessment of coordination.

Influence of Varied Human Movement Control on Task Performance and Feeling of Telepresence

2010 ◽  
Vol 19 (5) ◽  
pp. 463-481 ◽  
Author(s):  
Angelika Peer ◽  
Helena Pongrac ◽  
Martin Buss
Keyword(s):  
Task Performance ◽  
Degrees Of Freedom ◽  
Haptic Feedback ◽  
Full Range ◽  
Movement Control ◽  
Human Movement ◽  
Design Guidelines ◽  
Feedback Systems ◽  
Range Of Movement ◽  
High Degree

One of the main objectives in telerobotics is the development of a telemanipulation system that allows a high task performance to be achieved by simultaneously providing a high degree of telepresence. Specific mechatronic design guidelines and appropriate control algorithms as well as augmented visual, auditory, and haptic feedback systems are typical approaches adopted in this context. This work aims at formulating new design guidelines by incorporating human factors in the development process and analyzing the effects of varied human movement control on task performance and on the feeling of telepresence. While it is well known that humans are able to coordinate and integrate multiple degrees of freedom (DOF), the focus of this work is on how humans utilize rotational degrees of freedom provided by a human-system interface and if and how varied human movement control affects task performance and the feeling of telepresence. For this analysis, a telemanipulation experiment with varying degrees of freedom has been conducted. The results indicate that providing the full range of movement, even though this range is not necessary to accomplish a task, has a beneficial effect on the feeling of telepresence and task performance in terms of measured interaction forces. Further, increasing visual depth cues provided to the human operator also had a positive effect.

scholarly journals Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses

Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 370 ◽  
Author(s):  
Annik Imogen Gmel ◽  
Thomas Druml ◽  
Rudolf von Niederhäusern ◽  
Tosso Leeb ◽  
Markus Neuditschko
Keyword(s):  
Joint Angle ◽  
Association Studies ◽  
Genome Wide Association ◽  
Cranial Morphology ◽  
Genome Wide Association Studies ◽  
Joint Angles ◽  
Mineral Density ◽  
Mixed Effect ◽  
Stifle Joint ◽  
Genome Wide

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10−7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10−7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10−7); the poll on ECA1 (p = 6.83 × 10−7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10−7); and the carpal joint angle on ECA3 (p = 6.24 × 10−7), ECA4 (p = 6.07 × 10−7), and ECA7 (p = 8.83 × 10−7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.

scholarly journals Experimental and Numerical Study of Fracture Behavior of Rock-Like Material Specimens with Single Pre-Set Joint under Dynamic Loading

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2690
Author(s):  
Bo Pan ◽  
Xuguang Wang ◽  
Zhenyang Xu ◽  
Lianjun Guo ◽  
Xuesong Wang
Keyword(s):  
Crack Initiation ◽  
Crack Propagation ◽  
Joint Angle ◽  
Simulation Software ◽  
Dissipated Energy ◽  
Energy Structure ◽  
Joint Angles ◽  
Crack Penetration ◽  
Before And After ◽  
The Impact

The Split Hopkinson Pressure Bar (SHPB) is an apparatus for testing the dynamic stress-strain response of the cement mortar specimen with pre-set joints at different angles to explore the influence of joint attitudes of underground rock engineering on the failure characteristics of rock mass structure. The nuclear magnetic resonance (NMR) has also been used to measure the pore distribution and internal cracks of the specimen before and after the testing. In combination with numerical analysis, the paper systematically discusses the influence of joint angles on the failure mode of rock-like materials from three aspects of energy dissipation, microscopic damage, and stress field characteristics. The result indicates that the impact energy structure of the SHPB is greatly affected by the pre-set joint angle of the specimen. With the joint angle increasing, the proportion of reflected energy moves in fluctuation, while the ratio of transmitted energy to dissipated energy varies from one to the other. NMR analysis reveals the structural variation of the pores in those cement specimens before and after the impact. Crack propagation direction is correlated with pre-set joint angles of the specimens. With the increase of the pre-set joint angles, the crack initiation angle decreases gradually. When the joint angles are around 30°–75°, the specimens develop obvious cracks. The crushing process of the specimens is simulated by LS-DYNA software. It is concluded that the stresses at the crack initiation time are concentrated between 20 and 40 MPa. The instantaneous stress curve first increases and then decreases with crack propagation, peaking at different times under various joint angles; but most of them occur when the crack penetration ratio reaches 80–90%. With the increment of joint angles in specimens through the simulation software, the changing trend of peak stress is consistent with the test results.

A Model of the Human Spine: Forward and Inverse Kinematics

1992 ◽  
Author(s):  
Sunil Kumar Agrawal ◽  
Siyan Li ◽  
Glen Desmier
Keyword(s):  
Range Of Motion ◽  
Inverse Kinematics ◽  
Degrees Of Freedom ◽  
Kinematic Model ◽  
Joint Angles ◽  
Human Spine ◽  
Forward And Inverse Kinematics ◽  
Position And Orientation ◽  
Three Degrees Of Freedom ◽  
Adjacent Vertebra

Abstract The human spine is a sophisticated mechanism consisting of 24 vertebrae which are arranged in a series-chain between the pelvis and the skull. By careful articulation of these vertebrae, a human being achieves fine motion of the skull. The spine can be modeled as a series-chain with 24 rigid links, the vertebrae, where each vertebra has three degrees-of-freedom relative to an adjacent vertebra. From the studies in the literature, the vertebral geometry and the range of motion between adjacent vertebrae are well-known. The objectives of this paper are to present a kinematic model of the spine using the available data in the literature and an algorithm to compute the inter vertebral joint angles given the position and orientation of the skull. This algorithm is based on the observation that the backbone can be described analytically by a space curve which is used to find the joint solutions..

Alternative Inverse Kinematic Equations for General RRP and RRR Regional Structures of Manipulators

1996 ◽  
Author(s):  
Peregrine E. J. Riley
Keyword(s):  
Degrees Of Freedom ◽  
Joint Angle ◽  
Inverse Kinematic ◽  
Intersection Point ◽  
Degree Polynomial ◽  
Six Degrees Of Freedom ◽  
Common Intersection ◽  
Position And Orientation ◽  
Spatial Positioning ◽  
Orientational Structure

Abstract Many manipulators with six degrees of freedom are constructed with two distinct sections, a regional structure for spatial positioning, and an orientational structure having a common intersection point for the joint axes. With this arrangement, inverse kinematic solutions for position and orientation may be found separately. While solutions for general three link manipulators have been available since the work of Pieper in 1969, this paper presents new forms of the inverse kinematic equations for general RRP and RRR regional structures. Cartesian coordinates of the F-surface (generated by movement of the outer two joints) together with the outer joint angle are used as the equation variables. In addition, a second degree polynomial approxiamation of the equation may be used for quick iteration to a solution. It is hoped that these new equations will be useful by themselves and in workspace regions where solutions using equations in terms of the joint variables are numerically inaccurate or impossible.

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