scholarly journals Does the margin of stability measure predict stability of gait with a constrained base of support?

2019 ◽  
Author(s):  
Lakshdeep Gill ◽  
Andrew H. Huntley ◽  
Avril Mansfield
Keyword(s):  
Motion Capture ◽  
Three Dimensional ◽  
Centre Of Mass ◽  
Narrow Beam ◽  
Margin Of Stability ◽  
Stability Measure ◽  
Subsequent Step ◽  
Base Of Support ◽  
Mass Position ◽  
Healthy Participants

ABSTRACTThis study aimed to determine the validity of the centre of mass position (COM) position and extrapolated COM (XCOM), relative to the base of support, for predicting stability during a walking task where the base of support is constrained. Nine young healthy participants walked on a narrow beam. Three-dimensional motion capture was used to calculate the COM and XCOM relative to the base of support. Steps were classified as having either the COM or XCOM inside or outside the base of support, and were classified as successful (stable – foot placed on the beam) or failed (unstable – foot stepped off the beam). If the COM or XCOM are valid measures of stability, they should be within the base of support for successful steps and outside the base of support for failed steps. Classifying the COM and XCOM inside or outside the base of support correctly predicted successful or failed steps in 69% and 58% of cases, respectively. When the COM or XCOM were outside the base of support, walking faster seemed to help participants to maintain stability. The further the COM or XCOM were outside the base of support during a successful step, the more likely participants were to fail on a subsequent step. The results of this study suggest that both COM and XCOM are valid measures of stability during a beam walking task, but that classifying COM and XCOM as inside or outside the base of support may be over-simplistic.

scholarly journals A Three-Dimensional Skeletal Reconstruction of the Stem Amniote Orobates pabsti (Diadectidae): Analyses of Body Mass, Centre of Mass Position, and Joint Mobility

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0137284 ◽  
Author(s):  
John A. Nyakatura ◽  
Vivian R. Allen ◽  
Jonas Lauströer ◽  
Amir Andikfar ◽  
Marek Danczak ◽  
...  
Keyword(s):  
Body Mass ◽  
Three Dimensional ◽  
Joint Mobility ◽  
Centre Of Mass ◽  
Mass Centre ◽  
Mass Position ◽  
Skeletal Reconstruction

scholarly journals An investigation of the spatio-temporal parameters of gait and margins of stability throughout adulthood

2020 ◽  
Vol 17 (166) ◽  
pp. 20200194
Author(s):  
Nolan Herssens ◽  
Tamaya van Criekinge ◽  
Wim Saeys ◽  
Steven Truijen ◽  
Luc Vereeck ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Lateral Margin ◽  
Leg Length ◽  
Temporal Characteristics ◽  
Margin Of Stability ◽  
Temporal Parameters ◽  
Age Related ◽  
Support Domain ◽  
Spatio Temporal ◽  
Base Of Support

Age-related changes in the way of walking may induce changes in dynamic stability. Therefore, the relationship between age, spatio-temporal characteristics and margins of stability was examined. One hundred and five healthy adults aged between 20 and 89 years old were analysed on spatio-temporal characteristics and margins of stability using three-dimensional motion analysis. Subjects walked barefoot over a 12-m-long walkway at their preferred walking speed. Covariance among gait characteristics was reduced using a factor analysis, identifying domains of gait. The influence of age, gender, body mass index (BMI) and leg length on domains of gait and margins of stability was investigated using linear mixed models. A stepwise linear regression identified domains of gait predicting the variance in margins of stability. Four domains of gait explaining 74.17% of the variance were identified. Age had a significant influence on the medio-lateral margin of stability and the ‘variability', ‘pace' and ‘base of support' domain. BMI significantly influenced the medio-lateral margin of stability; gender and leg length had no influence on either of the margins of stability. The ‘base of support’ domain predicted 26% of the variance in the medio-lateral margin of stability. When considering the margins of stability, especially when comparing multiple groups, age, BMI and spatio-temporal parameters should be taken into account.

scholarly journals A novel Movement Amplification environment reveals effects of controlling lateral centre of mass motion on gait stability and metabolic cost

2020 ◽  
Vol 7 (1) ◽  
pp. 190889
Author(s):  
Mengnan/Mary Wu ◽  
Geoffrey L. Brown ◽  
Jane L. Woodward ◽  
Sjoerd M. Bruijn ◽  
Keith E. Gordon
Keyword(s):  
Metabolic Cost ◽  
Mass Motion ◽  
Step Width ◽  
Centre Of Mass ◽  
Cost Of Transport ◽  
Gait Patterns ◽  
Gait Stability ◽  
Foot Placement ◽  
Base Of Support ◽  
Healthy Participants

During human walking, the centre of mass (COM) laterally oscillates, regularly transitioning its position above the two alternating support limbs. To maintain upright forward-directed walking, lateral COM excursion should remain within the base of support, on average. As necessary, humans can modify COM motion through various methods, including foot placement. How the nervous system controls these oscillations and the costs associated with control are not fully understood. To examine how lateral COM motions are controlled, healthy participants walked in a ‘Movement Amplification’ force field that increased lateral COM momentum in a manner dependent on the participant's own motion (forces were applied to the pelvis proportional to and in the same direction as lateral COM velocity). We hypothesized that metabolic cost to control lateral COM motion would increase with the gain of the field. In the Movement Amplification field, participants were significantly less stable than during baseline walking. Stability significantly decreased as the field gain increased. Participants also modified gait patterns, including increasing step width, which increased the metabolic cost of transport as the field gain increased. These results support previous research suggesting that humans modulate foot placement to control lateral COM motion, incurring a metabolic cost.

A fast methodology to determine the characteristics of thousands of grains using three-dimensional X-ray diffraction. I. Overlapping diffraction peaks and parameters of the experimental setup

2012 ◽  
Vol 45 (4) ◽  
pp. 693-704 ◽  
Author(s):  
Hemant Sharma ◽  
Richard M. Huizenga ◽  
S. Erik Offerman
Keyword(s):  
Data Analysis ◽  
Three Dimensional ◽  
Experimental Setup ◽  
Centre Of Mass ◽  
X Ray Diffraction ◽  
X Ray ◽  
Overlapping Peaks ◽  
Diffraction Peaks ◽  
Mass Position

A data-analysis methodology is presented for the characterization of three-dimensional microstructures of polycrystalline materials from data acquired using three-dimensional X-ray diffraction (3DXRD). The method is developed for 3DXRD microscopy using a far-field detector and yields information about the centre-of-mass position, crystallographic orientation, volume and strain state for thousands of grains. This first part deals with pre-processing of the diffraction data for input into the algorithms presented in the second part [Sharma, Huizenga & Offerman (2012).J. Appl. Cryst.45, 705–718] for determination of the grain characteristics. An algorithm is presented for accurate identification of overlapping diffraction peaks from X-ray diffraction images, which has been an issue limiting the accuracy of experiments of this type. The algorithm works in two stages, namely the identification of overlapping peaks using a seeded watershed algorithm, and then the fitting of the peaks with a pseudo-Voigt shape function to yield an accurate centre-of-mass position and integrated intensity for the peaks. Regions consisting of up to six overlapping peaks can be successfully fitted. Two simulations and an experiment are used to verify the results of the algorithms. An example of the processing of diffraction images acquired in a 3DXRD experiment with a sample consisting of more than 1600 grains is shown. Furthermore, a procedure for the determination of the parameters of the experimental setup (global parameters) without the need for a calibration sample is presented and validated using simulations. This is immensely beneficial for simplifying experiments and the subsequent data analysis.

scholarly journals Estimation of the Centre of Mass From Motion Capture and Force Plate Recordings: A Study on the Elderly

2011 ◽  
Vol 8 (1) ◽  
pp. 67-84 ◽  
Author(s):  
S. Cotton ◽  
M. Vanoncini ◽  
P. Fraisse ◽  
N. Ramdani ◽  
E. Demircan ◽  
...  
Keyword(s):  
Motion Capture ◽  
Force Plate ◽  
The Elderly ◽  
The Body ◽  
Estimation Methods ◽  
Centre Of Mass ◽  
Joint Angles ◽  
Biomechanical Models ◽  
The Subject ◽  
Mass Position

The estimation of the centre of mass position in humans is usually based on biomechanical models developed from anthropometric tables. This method can potentially introduce errors in studies involving elderly people, since the ageing process is typically associated with a modification of the distribution of the body mass. In this paper, an alternative technique is proposed, and evaluated with an experimental study on 9 elderly volunteers. The technique is based on a virtual chain, identified from experimental data and locating the subject's centre of mass. Its configuration defines the location of the centre of mass, and is a function of the anatomical joint angles measured on the subject. This method is a valuable investigation tool in the field of geronto-technology, since it overcomes some of the problems encountered with other CoM estimation methods.

A fast methodology to determine the characteristics of thousands of grains using three-dimensional X-ray diffraction. II. Volume, centre-of-mass position, crystallographic orientation and strain state of grains

2012 ◽  
Vol 45 (4) ◽  
pp. 705-718 ◽  
Author(s):  
Hemant Sharma ◽  
Richard M. Huizenga ◽  
S. Erik Offerman
Keyword(s):  
Crystallographic Orientation ◽  
Strain State ◽  
Strain Tensor ◽  
Three Dimensional ◽  
Centre Of Mass ◽  
X Ray Diffraction ◽  
Computation Efficiency ◽  
Experimental Errors ◽  
Mass Position

This second part of the paper on an analysis strategy for data acquired using three-dimensional X-ray diffraction (3DXRD) describes the procedure for the determination of the grain characteristics for thousands of grains. The approach developed here is orders of magnitude faster than those presently available for indexing thousands of grains. Using information obtained from the steps described in Part I [Sharma, Huizenga & Offerman (2012).J. Appl. Cryst.45, 693–704], the volume, crystallographic orientation, centre-of-mass position and strain state of grains in the sample can be determined. The algorithms dealing with the determination of the orientation, centre-of-mass position and strain state of the grains are divided into two parts. The first deals with indexing,i.e.it assigns diffraction spots to individual grains assuming an unstrained lattice, and the second deals with the refinement of the crystallographic orientation, centre-of-mass position and strain state of the grains using the diffraction spots assigned during indexing. The different approaches to indexing that exist in the literature are presented and compared with the novel approach developed here. Indexing can be run in two modes depending on the number of grains. For large numbers of grains, the approach employs a novel sample `surface' scanning technique, in combination with a reduced number of search orientations, to achieve high robustness and computation efficiency. For small numbers of grains, the approach neglects the position of the diffracting grains in the sample in order to improve the computation efficiency. For unstrained samples, both modes of indexing and the subsequent process of refinement are validated using simulated data for 60 and 3000 grains. In both cases, the centre-of-mass position of the grains was determined with a mean error of 0.7 µm and the orientation was determined with a mean error of 0.0003°. Furthermore, an experiment was `mimicked' by introducing experimental errors into the simulation for 3000 grains. The resulting mean errors in the centre-of-mass position (2.1 µm) and orientation (0.008°) of the grains are higher than those for the ideal simulations, and the errors in an experiment will depend on the `true' experimental errors. The algorithms dealing with strained samples are validated using a simulation for 3000 grains with mimicked experimental errors. The centre-of-mass position, crystallographic orientation, normal strain tensor components and shear strain tensor components of the grains were determined with mean errors of 8 µm, 0.006°, 5.2 × 10−5and 2.8 × 10−5, respectively. The possibility of obtaining grain-level information for thousands of grains with a high speed of acquisition makes the technique very attractive forin situstudies of thermomechanical processes in polycrystalline materials.

scholarly journals A Novel Suture Training System for Open Surgery Replicating Procedures Performed by Experts Using Augmented Reality

2021 ◽  
Vol 45 (5) ◽  
Author(s):  
Yuri Nagayo ◽  
Toki Saito ◽  
Hiroshi Oyama
Keyword(s):  
Augmented Reality ◽  
Motion Capture ◽  
Open Surgery ◽  
Three Dimensional ◽  
Training System ◽  
Surgical Skills ◽  
Surgical Instruments ◽  
Interrupted Suture ◽  
Education Environment ◽  
Surgical Field

AbstractThe surgical education environment has been changing significantly due to restricted work hours, limited resources, and increasing public concern for safety and quality, leading to the evolution of simulation-based training in surgery. Of the various simulators, low-fidelity simulators are widely used to practice surgical skills such as sutures because they are portable, inexpensive, and easy to use without requiring complicated settings. However, since low-fidelity simulators do not offer any teaching information, trainees do self-practice with them, referring to textbooks or videos, which are insufficient to learn open surgical procedures. This study aimed to develop a new suture training system for open surgery that provides trainees with the three-dimensional information of exemplary procedures performed by experts and allows them to observe and imitate the procedures during self-practice. The proposed system consists of a motion capture system of surgical instruments and a three-dimensional replication system of captured procedures on the surgical field. Motion capture of surgical instruments was achieved inexpensively by using cylindrical augmented reality (AR) markers, and replication of captured procedures was realized by visualizing them three-dimensionally at the same position and orientation as captured, using an AR device. For subcuticular interrupted suture, it was confirmed that the proposed system enabled users to observe experts’ procedures from any angle and imitate them by manipulating the actual surgical instruments during self-practice. We expect that this training system will contribute to developing a novel surgical training method that enables trainees to learn surgical skills by themselves in the absence of experts.

scholarly journals The Effect of Lateral Column Lengthening on Subtalar Motion: Are We Trading Deformity for Stiffness?

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0004
Author(s):  
Brittany Hedrick ◽  
Anthony Riccio ◽  
Danielle M. Thomas ◽  
Claire Shivers ◽  
Matthew Siebert ◽  
...  
Keyword(s):  
Motion Capture ◽  
Three Dimensional ◽  
Deformity Correction ◽  
Porous Titanium ◽  
Testing System ◽  
Materials Testing ◽  
Lateral Column ◽  
Fresh Frozen ◽  
Lateral Column Lengthening ◽  
Paired T Test

Category: Hindfoot; Other Introduction/Purpose: While lengthening of the lateral column through a calcaneal neck osteotomy is an integral component of flatfoot reconstruction in younger patients with flexible planovalgus deformities, concern exists as to the effect of this intra- articular osteotomy on subtalar motion. The purpose of this study is to quantify the alterations in subtalar motion following lateral column lengthening (LCL). Methods: The subtalar motion of 14 fresh frozen cadaveric feet was assessed using a three-dimensional motion capture system and materials testing system (MTS). Following potting of the tibia and calcaneus, optic markers were placed into the tibia, calcaneus and talus. The MTS was used to apply a rotational force across the subtalar joint to a torque of 5Nm. Abduction/adduction, supination/pronation, and plantarflexion/dorsiflexion about the talus was recorded. Specimens then underwent LCL via a calcaneal neck osteotomy which was maintained with a 12mm porous titanium wedge. Repeat subtalar motion analysis was performed and compared to pre-LCL motion using a paired t-test. Results:: No statistically significant differences in subtalar abduction/adduction (10.9O vs. 11.8O degrees, p=.48), supination/pronation (3.5O vs. 2.7O, p=.31), or plantarflexion/dorsiflexion (1.6O vs 1.0O, p=.10) were identified following LCL. Conclusion:: No significant changes in subtalar motion were observed following lateral column lengthening in this biomechanical cadaveric study. While these findings do not obviate concerns of clinical subtalar stiffness following planovalgus deformity correction, they suggest that diminished postoperative subtalar motion may be due to soft tissue scarring rather than alterations of joint anatomy.

scholarly journals Three-Dimensional Body and Centre of Mass Kinematics in Alpine Ski Racing Using Differential GNSS and Inertial Sensors

2016 ◽  
Vol 8 (8) ◽  
pp. 671 ◽  
Author(s):  
Benedikt Fasel ◽  
Jörg Spörri ◽  
Matthias Gilgien ◽  
Geo Boffi ◽  
Julien Chardonnens ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Three Dimensional ◽  
Centre Of Mass
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