Two Kinematic Synergies in Voluntary Whole-Body Movements During Standing

2006 ◽  
Vol 95 (2) ◽  
pp. 636-645 ◽  
Author(s):  
Sandra M.S.F. Freitas ◽  
Marcos Duarte ◽  
Mark L. Latash
Keyword(s):  
Joint Angle ◽  
Center Of Pressure ◽  
Uncontrolled Manifold ◽  
Whole Body ◽  
Joint Angles ◽  
Body Movements ◽  
Uncontrolled Manifold Hypothesis ◽  
Kinematic Synergies ◽  
Trunk Orientation ◽  
Speed Accuracy

We used a particular computational approach, the uncontrolled manifold hypothesis, to investigate joint angle covariation patterns during whole-body actions performed by standing persons. We hypothesized that two kinematic synergies accounted for the leg/trunk joint covariation across cycles during a rhythmic whole-body motion to stabilize two performance variables, the trunk orientation in the external space and the horizontal position of the center of mass (COM). Subjects stood on a force plate and performed whole-body rhythmic movements for 45 s under visual feedback on one of the four variables, the position of the center of pressure or the angle in one of the three joints (ankle, knee, or hip). The Fitts-like paradigm was used with two target amplitudes and six indices of difficulty (ID) for each of the four variables. This was done to explore the robustness of kinematic postural synergies. A speed-accuracy trade-off was observed in all feedback conditions such that the movement time scaled with ID and the scaling differed between the two movement amplitudes. Principal-component (PC) analysis showed the existence of a single PC in the joint space that accounted for over 95% of the joint angle variance. Analysis within the uncontrolled manifold hypothesis has shown that data distributions in the joint angle space were compatible with stabilization of both trunk orientation and COM location. We conclude that trunk orientation and the COM location are stabilized by co-varied changes of the major joint angles during whole-body movements. Despite the strong effects of movement amplitude and ID on performance, the structure of the joint variance showed only minor dependence on these task parameters. The two kinematic synergies (co-varied changes in the joint angles that stabilized the COM location and trunk orientation) have proven to be robust over a variety of tasks.

scholarly journals Kinematic synergies during saccades involving whole-body rotation: A study based on the uncontrolled manifold hypothesis

2010 ◽  
Vol 29 (2) ◽  
pp. 243-258 ◽  
Author(s):  
Adriana M. Degani ◽  
Alessander Danna-Dos-Santos ◽  
Thomas Robert ◽  
Mark L. Latash
Keyword(s):  
Uncontrolled Manifold ◽  
Whole Body ◽  
Body Rotation ◽  
Uncontrolled Manifold Hypothesis ◽  
Kinematic Synergies

Emotional State Impacts Center of Pressure Displacement Before Forward Gait Initiation

2015 ◽  
Vol 31 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Bradley Fawver ◽  
Garrett F. Beatty ◽  
Kelly M. Naugle ◽  
Chris J. Hass ◽  
Christopher M. Janelle
Keyword(s):  
Center Of Pressure ◽  
Emotional Reactions ◽  
Quiet Standing ◽  
Whole Body ◽  
Gait Initiation ◽  
Emotional States ◽  
Body Movements ◽  
Planning Period ◽  
Postural Changes ◽  
The Impact

Emotional states influence whole-body movements during quiet standing, gait initiation, and steady state gait. A notable gap exists, however, in understanding how emotions affect postural changes during the period preceding the execution of planned whole-body movements. The impact of emotion-induced postural reactions on forthcoming posturomotor movements remains unknown. We sought to determine the influence of emotional reactions on center of pressure (COP) displacement before the initiation of forward gait. Participants (N = 23, 14 females) stood on a force plate and initiated forward gait at the offset of an emotional image (representing five discrete categories: attack, sad faces, erotica, happy faces, and neutral objects). COP displacement in the anteroposterior direction was quantified for a 2 second period during image presentation. Following picture onset, participants produced a posterior postural response to all image types. The greatest posterior displacement was occasioned in response to attack or threat stimuli compared with happy faces and erotica images. Results suggest the impact of emotional states on gait behavior begins during the motor planning period before the preparatory phase of gait initiation, and manifests in center of pressure displacement alterations.

scholarly journals Principal components of hand kinematics and neurophysiological signals in motor cortex during reach to grasp movements

2014 ◽  
Vol 112 (8) ◽  
pp. 1857-1870 ◽  
Author(s):  
Mohsen Mollazadeh ◽  
Vikram Aggarwal ◽  
Nitish V. Thakor ◽  
Marc H. Schieber
Keyword(s):  
Motor Cortex ◽  
Joint Angle ◽  
Principal Component ◽  
Field Potentials ◽  
Joint Angles ◽  
Reach To Grasp ◽  
Lower Accuracy ◽  
Neurophysiological Data ◽  
Kinematic Synergies ◽  
Cross Correlations

A few kinematic synergies identified by principal component analysis (PCA) account for most of the variance in the coordinated joint rotations of the fingers and wrist used for a wide variety of hand movements. To examine the possibility that motor cortex might control the hand through such synergies, we collected simultaneous kinematic and neurophysiological data from monkeys performing a reach-to-grasp task. We used PCA, jPCA and isomap to extract kinematic synergies from 18 joint angles in the fingers and wrist and analyzed the relationships of both single-unit and multiunit spike recordings, as well as local field potentials (LFPs), to these synergies. For most spike recordings, the maximal absolute cross-correlations of firing rates were somewhat stronger with an individual joint angle than with any principal component (PC), any jPC or any isomap dimension. In decoding analyses, where spikes and LFP power in the 100- to 170-Hz band each provided better decoding than other LFP-based signals, the first PC was decoded as well as the best decoded joint angle. But the remaining PCs and jPCs were predicted with lower accuracy than individual joint angles. Although PCs, jPCs or isomap dimensions might provide a more parsimonious description of kinematics, our findings indicate that the kinematic synergies identified with these techniques are not represented in motor cortex more strongly than the original joint angles. We suggest that the motor cortex might act to sculpt the synergies generated by subcortical centers, superimposing an ability to individuate finger movements and adapt the hand to grasp a wide variety of objects.

scholarly journals Physically Consistent Whole-Body Kinematics Assessment Based on an RGB-D Sensor. Application to Simple Rehabilitation Exercises

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2848
Author(s):  
Jessica Colombel ◽  
Vincent Bonnet ◽  
David Daney ◽  
Raphael Dumas ◽  
Antoine Seilles ◽  
...  
Keyword(s):  
Kalman Filter ◽  
Extended Kalman Filter ◽  
Joint Angle ◽  
Statistical Parametric Mapping ◽  
Biomechanical Model ◽  
Practical Method ◽  
Covariance Matrices ◽  
Whole Body ◽  
Joint Angles ◽  
Optimal Tuning

This work proposes to improve the accuracy of joint angle estimates obtained from an RGB-D sensor. It is based on a constrained extended Kalman Filter that tracks inputted measured joint centers. Since the proposed approach uses a biomechanical model, it allows physically consistent constrained joint angles and constant segment lengths to be obtained. A practical method that is not sensor-specific for the optimal tuning of the extended Kalman filter covariance matrices is provided. It uses reference data obtained from a stereophotogrammetric system but it has to be tuned only once since it is task-specific only. The improvement of the optimal tuning over classical methods in setting the covariance matrices is shown with a statistical parametric mapping analysis. The proposed approach was tested with six healthy subjects who performed four rehabilitation tasks. The accuracy of joint angle estimates was assessed with a reference stereophotogrammetric system. Even if some joint angles, such as the internal/external rotations, were not well estimated, the proposed optimized algorithm reached a satisfactory average root mean square difference of 9.7 ∘ and a correlation coefficient of 0.8 for all joints. Our results show that an affordable RGB-D sensor can be used for simple in-home rehabilitation when using a constrained biomechanical model.

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.

Multi-Objective Optimization of Human Gait With a Discomfort Function

2016 ◽  
Author(s):  
Hyun-Jung Kwon ◽  
Hyun-Joon Chung ◽  
Yujiang Xiang
Keyword(s):  
Joint Torque ◽  
Upper Body ◽  
Whole Body ◽  
Human Gait ◽  
Multi Objective Optimization ◽  
Joint Angles ◽  
Backward Walking ◽  
Multi Objective ◽  
Body Model ◽  
Neutral Angle

The objective of this study was to develop a discomfort function for including a high DOF upper body model during walking. A multi-objective optimization (MOO) method was formulated by minimizing dynamic effort and the discomfort function simultaneously. The discomfort function is defined as the sum of the squares of deviation of joint angles from their neutral angle positions. The dynamic effort is the sum of the joint torque squared. To investigate the efficacy of the proposed MOO method, backward walking simulation was conducted. By minimizing both dynamic effort and the discomfort function, a 3D whole body model with a high DOF upper body for walking was demonstrated successfully.

Postural Preparation to Making a Step: Is There a “Motor Program” for Postural Preparation?

2007 ◽  
Vol 23 (4) ◽  
pp. 261-274 ◽  
Author(s):  
Adriana M. Degani ◽  
Alessander Danna-Dos-Santos ◽  
Mark L. Latash
Keyword(s):  
Reaction Time ◽  
Simple Reaction Time ◽  
Center Of Pressure ◽  
Motor Program ◽  
Whole Body ◽  
Single Motor ◽  
Simple Reaction ◽  
Specific Manner ◽  
Young Subjects ◽  
Straight Ahead

We tested the hypothesis that a sequence of mechanical events occurs preceding a step that scales in time and magnitude as a whole in a task-specific manner, and is a reflection of a “motor program.” Young subjects made a step under three speed instructions and four tasks: stepping straight ahead, down a stair, up a stair, and over an obstacle. Larger center-of-pressure (COP) and force adjustments in the anteriorposterior direction and smaller COP and force adjustments in the mediolateral direction were seen during stepping forward and down a stair, as compared with the tasks of stepping up a stair and over an obstacle. These differences were accentuated during stepping under the simple reaction time instruction. These results speak against the hypothesis of a single motor program that would underlie postural preparation to stepping. They are more compatible with the reference configuration hypothesis of whole-body actions.

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