Dynamic Optimization of Human Walking

2001 ◽  
Vol 123 (5) ◽  
pp. 381-390 ◽  
Author(s):  
Frank C. Anderson ◽  
Marcus G. Pandy
Keyword(s):  
Dynamic Optimization ◽  
Gait Cycle ◽  
Three Dimensional ◽  
Optimization Theory ◽  
The Body ◽  
Metabolic Energy ◽  
Unit Distance ◽  
Terminal Constraints ◽  
Muscle Activations ◽  
The Right

A three-dimensional, neuromusculoskeletal model of the body was combined with dynamic optimization theory to simulate normal walking on level ground. The body was modeled as a 23 degree-of-freedom mechanical linkage, actuated by 54 muscles. The dynamic optimization problem was to calculate the muscle excitation histories, muscle forces, and limb motions subject to minimum metabolic energy expenditure per unit distance traveled. Muscle metabolic energy was calculated by summing five terms: the basal or resting heat, activation heat, maintenance heat, shortening heat, and the mechanical work done by all the muscles in the model. The gait cycle was assumed to be symmetric; that is, the muscle excitations for the right and left legs and the initial and terminal states in the model were assumed to be equal. Importantly, a tracking problem was not solved. Rather, only a set of terminal constraints was placed on the states of the model to enforce repeatability of the gait cycle. Quantitative comparisons of the model predictions with patterns of body-segmental displacements, ground-reaction forces, and muscle activations obtained from experiment show that the simulation reproduces the salient features of normal gait. The simulation results suggest that minimum metabolic energy per unit distance traveled is a valid measure of walking performance.

Investigation into effects of cooling rate on properties of polyamide 12 parts in the multi jet fusion process

2020 ◽  
Vol 26 (10) ◽  
pp. 1789-1795
Author(s):  
Mattia Mele ◽  
Giampaolo Campana ◽  
Gregorio Pisaneschi ◽  
Gian Luca Monti
Keyword(s):  
Cooling Rate ◽  
Three Dimensional ◽  
The Body ◽  
Scanning Calorimetry ◽  
Content Type ◽  
Polyamide 12 ◽  
Body Of Knowledge ◽  
Cooling Phase ◽  
The Right ◽  
High Building

Purpose Multi jet fusion is an industrial additive manufacturing technology characterised by high building speed and considerable properties of the parts. The cooling phase represents a crucial step to determine productivity, since it can take up to 4.5 times the building time. The purpose of this paper is to investigate into effects of cooling rate on parts manufactured by multi jet fusion. Crystallinity, density, distortions and mechanical properties of specimens produced through an HP multi jet fusion 4200 are examined. Design/methodology/approach An experimental activity is carried out on specimens cooled down at three different rates. Properties of the parts are analysed by means of differential scanning calorimetry, optical microscopy, three-dimensional scanning and tensile testing. Originality/value The present work makes a contribution to the body of knowledge providing correlations between the cooling phase of multi jet fusion and part properties. These results can be used to choose the right balance between production time and product quality.

scholarly journals Neuromuscular adjustments of gait associated with unstable conditions

2015 ◽  
Vol 114 (5) ◽  
pp. 2867-2882 ◽  
Author(s):  
G. Martino ◽  
Y. P. Ivanenko ◽  
A. d'Avella ◽  
M. Serrao ◽  
A. Ranavolo ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Gait Cycle ◽  
Activity Patterns ◽  
Human Locomotion ◽  
Support Surface ◽  
Muscle Activations ◽  
The Right ◽  
Weighting Coefficients ◽  
Synergistic Muscle ◽  
Non Negative Matrix Factorization

A compact description of coordinated muscle activity is provided by the factorization of electromyographic (EMG) signals. With the use of this approach, it has consistently been shown that multimuscle activity during human locomotion can be accounted for by four to five modules, each one comprised of a basic pattern timed at a different phase of gait cycle and the weighting coefficients of synergistic muscle activations. These modules are flexible, in so far as the timing of patterns and the amplitude of weightings can change as a function of gait speed and mode. Here we consider the adjustments of the locomotor modules related to unstable walking conditions. We compared three different conditions, i.e., locomotion of healthy subjects on slippery ground (SL) and on narrow beam (NB) and of cerebellar ataxic (CA) patients on normal ground. Motor modules were computed from the EMG signals of 12 muscles of the right lower limb using non-negative matrix factorization. The unstable gait of SL, NB, and CA showed significant changes compared with controls in the stride length, stride width, range of angular motion, and trunk oscillations. In most subjects of all three unstable conditions, >70% of the overall variation of EMG waveforms was accounted for by four modules that were characterized by a widening of muscle activity patterns. This suggests that the nervous system adopts the strategy of prolonging the duration of basic muscle activity patterns to cope with unstable conditions resulting from either slippery ground, reduced support surface, or pathology.

scholarly journals Use of a Single Wearable Sensor to Evaluate the Effects of Gait and Pelvis Asymmetries on the Components of the Timed Up and Go Test, in Persons with Unilateral Lower Limb Amputation

Sensors ◽  
2021 ◽  
Vol 22 (1) ◽  
pp. 95
Author(s):  
Maria Stella Valle ◽  
Antonino Casabona ◽  
Ilenia Sapienza ◽  
Luca Laudani ◽  
Alessandro Vagnini ◽  
...  
Keyword(s):  
Gait Cycle ◽  
Inertial Sensor ◽  
Three Dimensional ◽  
The Body ◽  
Limb Amputation ◽  
Control Group ◽  
Timed Up And Go ◽  
Physical Mobility ◽  
Group A ◽  
First Time

The Timed Up and Go (TUG) test quantifies physical mobility by measuring the total performance time. In this study, we quantified the single TUG subcomponents and, for the first time, explored the effects of gait cycle and pelvis asymmetries on them. Transfemoral (TF) and transtibial (TT) amputees were compared with a control group. A single wearable inertial sensor, applied to the back, captured kinematic data from the body and pelvis during the 10-m walk test and the TUG test. From these data, two categories of symmetry indexes (SI) were computed: One SI captured the differences between the antero-posterior accelerations of the two sides during the gait cycle, while another set of SI quantified the symmetry over the three-dimensional pelvis motions. Moreover, the total time of the TUG test, the time of each subcomponent, and the velocity of the turning subcomponents were measured. Only the TF amputees showed significant reductions in each SI category when compared to the controls. During the TUG test, the TF group showed a longer duration and velocity reduction mainly over the turning subtasks. However, for all the amputees there were significant correlations between the level of asymmetries and the velocity during the turning tasks. Overall, gait cycle and pelvis asymmetries had a specific detrimental effect on the turning performance instead of on linear walking.

Stratified rotating flow over and around isolated three-dimensional topography

1987 ◽  
Vol 322 (1564) ◽  
pp. 213-241 ◽  
Keyword(s):  
Numerical Model ◽  
Three Dimensional ◽  
Wave Pattern ◽  
The Body ◽  
Lee Waves ◽  
Lee Wave ◽  
Long Time ◽  
Dynamical Parameters ◽  
The Right ◽  
Eddy Shedding

Laboratory and numerical experiments have been conducted on the flow of a linearly stratified rotating fluid past isolated obstacles of revolution (conical and cosinesquared profiles). Laboratory experiments are considered for a range of Rossby, Ekman and Burger numbers, the pertinent dynamical parameters of the system. In these experiments, inertial, Coriolis, pressure, viscous and buoyancy forces all play a significant role. Emphasis is given to examining the nature of the time development of the flow fields as well as its long-time behaviour, including eddy shedding. It is shown, for example, that increased stratification tends to diminish the steering effect of the obstacle, other parameters being fixed, at elevation levels above the topography. At levels below the top of the obstacle, increased stratification tends to force the fluid around rather than over the body and this, in turn, tends to develop vortex shedding at smaller Reynolds numbers than would occur in corresponding lower stratification cases. Data for the cone reveal that the Strouhal number for the eddy-shedding regime is relatively insensitive to the values of Ro , Ek and S for the range of parameters investigated. Stratification tends to induce lee waves in the topography wake, and the nature of this lee-wave pattern is modified by the presence of rotation. For example, it is demonstrated that for vertically upward rotation, the lee waves on the right, facing downstream, have a larger amplitude than their counterparts at the same location on the left. The steering effects, as predicted by a three-level quasigeostrophic numerical model, are shown to be in good agreement with the laboratory results for a narrow range of parameter space. The numerical model is used to examine the effects of rotation, friction and stratification in modifying the flow. The quasigeostrophic numerical simulations do not produce eddy shedding, and it is concluded that a full, primitive equation numerical model would be needed to explore this phenomenon.

The Effect of Task Asymmetry and Number of Hands on Spinal Loading

1997 ◽  
Vol 41 (1) ◽  
pp. 647-651
Author(s):  
Kermit G. Davis ◽  
William S. Marras ◽  
Kevin P. Granata
Keyword(s):  
Sagittal Plane ◽  
Three Dimensional ◽  
The Body ◽  
Lateral Shear ◽  
Spinal Loads ◽  
Trade Offs ◽  
Hands On ◽  
Asymmetric Lifting ◽  
The Right ◽  
Anterior Posterior

This study documented three-dimensional spine loading associated with asymmetric lifting while using either one or two hands to perform the task. Lift asymmetry was defined as a function of the load origin relative to the sagittal plane of the body. Lifts occurred at 0, 30, or 60 degrees off the sagittal plane on both sides of the body (lifting from the right and from the left relative to the sagittal plane). Ten subjects lifted a 13.7 kg box from one of these origins to a sagittally symmetric destination. Spinal loads were estimated through the use of a validated EMG-assisted model. Spine compression and lateral shear forces increased as the lift origin became more asymmetric. However, spine compression and lateral shear increased by about twice the rate when lifting from origins to the left of the sagittal plane compared to lifting from origins to the right of the sagittal plane. Anterior-posterior spinal shear decreased as asymmetry increased with larger decreases occurring when lift origins occurred to the right of the sagittal plane. One-hand lifting changed the compression and shear profiles significantly. One-hand lifts using the hand on the same side of the body as the load resulted in compression forces that were approximately equal to those observed when lifting with two hands in a sagittally symmetric position. Anterior -posterior shear decreased and lateral shear increased under these conditions. These results reflect the trade-offs that must be considered among spinal forces during asymmetric lifting while using one or two hands.

scholarly journals Implementasi Metode Euclidean Distance untuk Rekomendasi Ukuran Pakaian pada Aplikasi Ruang Ganti Virtual

2018 ◽  
Vol 5 (2) ◽  
pp. 129
Author(s):  
Rezky Rizaldi ◽  
Arik Kurniawati ◽  
Cucun Very Angkoso
Keyword(s):  
Augmented Reality ◽  
Euclidean Distance ◽  
Recommendation System ◽  
Three Dimensional ◽  
Positive Influence ◽  
The Body ◽  
Online Store ◽  
3 Dimensional ◽  
Potential Buyer ◽  
The Right

<p class="Abstrak">Perkembangan jual beli garmen secara <em>online</em>, dihadapkan pada kenyataan adanya 70% pengembalian produk oleh pembeli, akibat ketidaksesuaian antara harapan dan kenyataan model serta ukuran garmen. Kehadiran <em>virtual fitting room</em> secara <em>online</em>, diharapkan mampu mengurangi adanya pengembalian produk, memberikan pengaruh positif terhadap keistimewaan suatu produk, keinginan untuk membeli dan kepastian membeli secara <em>online</em>. <em>Virtual Fitting Room</em> ini bisa diimplementasikan pada toko <em>online</em> ataupun toko baju seperti biasa. Tahapan penelitian meliputi : penerapan teknologi <em>kinect</em> untuk mendapatkan data <em>skeleton</em> dari calon pembeli yang digunakan sebagai dasar untuk memberikan rekomendasi ukuran pakaian, selanjutnya perhitungan <em>euclidean distance</em> digunakan untuk menghitung ukuran punggung calon pembeli dan terakhir penerapan teknologi <em>augmented reality</em> untuk menampilkan pakaian <em>virtual</em> 3 dimensi yang melekat tepat di badan calon pembeli. Sistem rekomendasi ini mampu menampilkan calon pembeli dengan menggunakan baju virtual 3 dimensi yang sesuai dengan ukuran rekomendasi dari sistem (S,M,L, atau XL). Sistem ini juga memberikan fitur bagi calon pembeli untuk mencoba model pakaian lainnya. Sistem dapat memperlihatkan baju virtual 3 dimensi yang tetap melekat pada badan calon pembeli, ketika melakukan rotasi ke kanan 90<sup>0</sup>, ke kiri 90<sup>0</sup>, balik kanan 180<sup>0</sup> dan balik kiri 180<sup>0</sup>. Hasil uji coba sistem rekomendasi ukuran pakaian ini akan berjalan secara optimal jika pengaturan ketinggian <em>kinect</em> sebesar 55 cm dari tanah. Untuk ketinggian <em>kinect</em> 55cm, 65cm dan 75 cm dari tanah, sistem ini mampu menyajikan kesesuaian rekomendasi ukuran dibandingkan dengan ukuran asli dari calon pembeli sebesar 70%.</p><p class="Abstrak"> </p><p><strong>Kata kunci</strong>: <em>k</em><em>inect, augmented reality, euclidean distance</em><em>, virtual fitting room</em><strong></strong></p><p class="Judul2"> </p><p class="Judul2"><em>Abstract</em></p><p class="Judul2"><em>The development of online garment sale, faced with the fact that there is 70% return of product by the buyer, due to a mismatch between expectation and reality of model and garment size. The presence of virtual fitting room in the online store is expected to reduce the return of products, give a positive influence on the privilege of a product, the desire to buy and certainty to buy online. Virtual Fitting Room can be implemented in the online store or clothing store as usual. The research stages include the application of Kinect technology to obtain skeleton data from prospective buyers used as a basis for providing system recommendations, then euclidean distance calculation is used to calculate the size back potential buyers, and lastly application of augmented reality technology to display the right three-dimensional virtual clothing in potential buyer body. This recommendation system can present potential buyers by using 3-dimensional virtual shirts attached to their bodies by the recommended size of the system (S, M, L, or XL). This system also provides features for potential buyers to try other clothing models. The system can show a 3-dimensional virtual shirt that remains attached to the body of potential buyers, while rotating right 90<sup>0</sup>, left 90<sup>0</sup>, right turn 180<sup>0</sup> and left turn 180<sup>0</sup>. The test results of this clothing size recommendation system will run optimally if the Kinect height setting of 55 cm from the ground. For the Kinect height of 55cm, 65cm and 75cm from the ground, the system can present the recommended size with the original size of the potential buyer of 70%.</em></p><p class="Judul2"> </p><p><strong>Keywords</strong>: <em>kinect, augmented reality, euclidean distance, virtual fitting room</em></p>

scholarly journals Kinematics of male Eupalaestrus weijenberghi (Araneae, Theraphosidae) locomotion on different substrates and inclines

PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7748 ◽  
Author(s):  
Valentina Silva-Pereyra ◽  
C Gabriel Fábrica ◽  
Carlo M. Biancardi ◽  
Fernando Pérez-Miles
Keyword(s):  
The Body ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Time Lags ◽  
External Work ◽  
Gait Patterns ◽  
Unit Distance ◽  
Body Segments ◽  
Gait Parameters

Background The mechanics and energetics of spider locomotion have not been deeply investigated, despite their importance in the life of a spider. For example, the reproductive success of males of several species is dependent upon their ability to move from one area to another. The aim of this work was to describe gait patterns and analyze the gait parameters of Eupalaestrus weijenberghi (Araneae, Theraphosidae) in order to investigate the mechanics of their locomotion and the mechanisms by which they conserve energy while traversing different inclinations and surfaces. Methods Tarantulas were collected and marked for kinematic analysis. Free displacements, both level and on an incline, were recorded using glass and Teflon as experimental surfaces. Body segments of the experimental animals were measured, weighed, and their center of mass was experimentally determined. Through reconstruction of the trajectories of the body segments, we were able to estimate their internal and external mechanical work and analyze their gait patterns. Results Spiders mainly employed a walk-trot gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected regarding the different planes or surfaces with respect to duty factor, time lags, stride frequency, and stride length. However, postural changes were observed on slippery surfaces. The mechanical work required for traversing a level plane was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all of the total mechanical work. The internal work was extremely low and did not rise as the gradient increased. Discussion Our results support the idea of considering the eight limbs functionally divided into two quadrupeds in series. The anterior was composed of the first two pairs of limbs, which have an explorative and steering purpose and the posterior was more involved in supporting the weight of the body. The mechanical work to move one unit of mass a unit distance is almost constant among the different species tested. However, spiders showed lower values than expected. Minimizing the mechanical work could help to limit metabolic energy expenditure that, in small animals, is relatively very high. However, energy recovery due to inverted pendulum mechanics only accounts for only a small fraction of the energy saved. Adhesive setae present in the tarsal, scopulae, and claw tufts could contribute in different ways during different moments of the step cycle, compensating for part of the energetic cost on gradients which could also help to maintain constant gait parameters.

scholarly journals Kinematics of males Eupalaestrus weijenberghi (Araneae, Theraphosidae) locomotion on different substrates and inclines

2019 ◽  
Author(s):  
Valentina Silva-Pereyra ◽  
C Gabriel Fábrica ◽  
Carlo M Biancardi ◽  
Fernando Pérez-Miles
Keyword(s):  
Energy Saving ◽  
The Body ◽  
Mechanical Work ◽  
Metabolic Energy ◽  
Energetic Cost ◽  
Time Lags ◽  
Gait Patterns ◽  
Unit Distance ◽  
Body Segments ◽  
Gait Parameters

Background: For males of several terrestrial spiders the reproductive success depends to their locomotors performances. However, their mechanics of locomotion has been scarcely investigated. Aim of this work was to describe the gait patterns, analyse the gait parameters, the mechanics of locomotion and the energy saving mechanisms of Eupalaestrus weijenberghi (Araneae, Theraphosidae) on different inclinations and surfaces. Methods: Tarantulas were collected and marked for kinematic analysis. Free displacements, both at level and on incline, were recorded using two different experimental surfaces: glass and Teflon. Body segments of the experimental animals have been measured, weighted and their centre of mass experimentally determined. Through the reconstruction of trajectories of the body segments, we estimate the mechanical internal and external works and analysed the gait patterns. Results: Four gait patterns have been described, but spiders mainly employed a walk-trot-like gait. Significant differences between the first two pairs and the second two pairs were detected. No significant differences were detected among different planes or surfaces in duty factor, time lags, stride frequency and stride length. However, postural changes were observed on slippery surfaces. The mechanical work at level was lower than expected. In all conditions, the external work, and within it the vertical work, accounted for almost all the total mechanical work. The internal work was extremely low, and did not increase with gradient. Discussion: Our results support the idea of the two quadrupeds in series: the anterior composed by the first two pairs of limbs, with more explorative and steering purpose, and the posterior more involved in supporting the body weight. The mechanical work to move one unit mass a unit distance is almost constant among the different species. However spiders show lower values than expected. Minimizing the mechanical work could help to limit the metabolic energy expenditure that, in small animals, is relatively very high. However, the energy recovery due to the inverted pendulum mechanics only account for a small part of energy saving. Adhesive setae present in the tarsal, scopulae and claw tufts, would participate in different ways during different moments of the step cycle, compensating part of the energetic cost on gradient, and helping to maintain constant the gait parameters.

scholarly journals Electromyographic analysis of the gait cycle phases of boxer dogs

2016 ◽  
Vol 68 (4) ◽  
pp. 931-937 ◽  
Author(s):  
J.F. Araújo ◽  
F.B. Rodrigues ◽  
F.G. Abadia ◽  
F.M. Gervásio ◽  
G.B.N. Mendonça ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Gait Cycle ◽  
Biceps Brachii ◽  
Rectus Femoris ◽  
The Body ◽  
Triceps Brachii ◽  
Muscle Groups ◽  
Electromyographic Analysis ◽  
The Right ◽  
Boxer Dogs

ABSTRACT Systematic studies involving technologies such as surface electromyography (sEMG) may provide important data that enable veterinarians to recognize musculoskeletal, ligamentous, and neurological alterations. The aim of this study was to describe the gait cycle phases and the timing of muscle activation in healthy Boxer dogs during gait by means of sEMG. The gait cycle of seven Boxer dogs was evaluated and sEMG was recorded from the biceps brachii, triceps brachii, brachiocephalic, rectus femoris, semitendinosus, semimembranosus, and superficial gluteal muscles of the right hemibody. Circular monopolar Ag/AgCl electrodes were attached to the mean point between the motor point and the muscle insertion. The electromyographic signals were collected by an active interface with 20-fold gain in a bipolar differential configuration using a 16-channel signal conditioner (EMG Systems Brasil), while the dogs walked on a treadmill at a speed of 2m/s. Pearson's correlation was used for the statistical analysis. A positive correlation was found between the rectus femoris and biceps brachii (r= 0.81); superficial gluteal and triceps brachii (r= 0.69); semitendinosus-semimembranosus and biceps brachii (r= 0.76); and rectus femoris and semitendinosus and semimembranosus muscle groups (r=0.99). The biceps brachii and brachiocephalic muscles work in tandem to position the thoracic limb during the gait cycle, while the semitendinosus-semimembranosus group flexes the knee and, simultaneously with the quadriceps that flexes the hip, prevents the contact of the pelvic limb with the ground during the swing phase. The body is propelled forward by the triceps brachii muscle, which extends the elbow and flexes the shoulder at the final contact, while the superficial gluteal muscle extends the hip.

scholarly journals Mechanosensitivity of amoeboid cells crawling in 3D

2021 ◽  
Author(s):  
Florian Gaertner ◽  
Patricia Reis-Rodrigues ◽  
Ingrid de Vries ◽  
Miroslav Hons ◽  
Juan Aguilera ◽  
...  
Keyword(s):  
Three Dimensional ◽  
The Body ◽  
Three Dimensions ◽  
Cortical Actin ◽  
Actin Networks ◽  
Motile Cells ◽  
Spatio Temporal ◽  
Adhesive Interactions ◽  
The Right ◽  
Amoeboid Cells

Efficient immune-responses require migrating leukocytes to be in the right place at the right time. When crawling through the body amoeboid leukocytes must traverse complex three-dimensional tissue-landscapes obstructed by extracellular matrix and other cells, raising the question how motile cells adapt to mechanical loads to overcome these obstacles. Here we reveal the spatio-temporal configuration of cortical actin-networks rendering amoeboid cells mechanosensitive in three-dimensions, independent of adhesive interactions with the microenvironment. In response to compression, Wiskott-Aldrich syndrom protein (WASp) assembles into dot-like structures acting as nucleation sites for actin spikes that in turn push against the external load. High precision targeting of WASp to objects as delicate as collagen fibers allows the cell to locally and instantaneously deform its viscoelastic surrounding in order to generate space for forward locomotion. Such pushing forces are essential for fast and directed leukocyte migration in fibrous and cell-packed tissues such as skin and lymph nodes.

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