Nordic walking multibody analysis and experimental identification

2020 ◽  
pp. 175433712091926
Author(s):  
Caterina Russo ◽  
Francesco Mocera ◽  
Aurelio Somà
Keyword(s):  
Reaction Force ◽  
Standard Technique ◽  
The Body ◽  
Body Motion ◽  
Body Segment ◽  
Nordic Walking ◽  
Cycle Frequency ◽  
Experimental Identification ◽  
Body Model ◽  
Multi Body

The widespread diffusion of Nordic walking as a trending sport discipline has increased the need for a tool to study the movement, both at the beginner and professional level. This article presents a methodology for the analysis of the body motion during Nordic walking. The main goal was to design a numerical tool able to replicate human body behaviour when performing this sport. With this approach, it is possible to study several biomechanical aspects, like the kinematics of each body segment, estimating loads applied to the joints for given tasks. Results can be used to compare the user movements with a standard technique implemented in the virtual environment. In fact, using a specific monitoring device developed in previous works, different parameters like the pole angle, arms cycle frequency and synchronization, as well as the pushing force applied to the ground, can be measured during the activity. This acquisition system can be used to save data to be compared with results from the standard numerical model, evaluating the user performance. In this work, numerical results were compared and discussed with measurements from the aforementioned device in terms of pole force and pole angle. The ground reaction force obtained with the multi-body model during Nordic walking was then compared with results from the literature.

A Finite Element Investigation of a Functional Spine Unit in Conjunction With a Multi-Body Model of the Lumbar Spine for Impact Dynamics

Volume 2 ◽  
2004 ◽  
Author(s):  
Volkan Esat ◽  
Memis Acar
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Reaction Force ◽  
Element Model ◽  
Fe Model ◽  
Body Model ◽  
Spine Model ◽  
Spinal Segments ◽  
Whole Spine ◽  
Multi Body

In this study, the finite element (FE) technique was used in conjunction with multi-body modelling to simulate and analyse the dynamic behaviour of the spinal segments in order to investigate the effects of impact loadings on the lumbar spine. A 3-D multi-body model of the lumbar spine and an FE model of the L2-L3 motion segment were developed. Both models were validated for flexion and compression loadings, showing good agreements with a previously validated lumbar spine model. The predictions of the multi-body model under dynamic impact loading conditions such as reaction forces at lumbar motion segments were employed as force boundary conditions for the finite element model of the selected functional spine unit (FSU). Stress and pressure in the intervertebral disc element and the reaction force at a specific vertebral level were presented. This approach has the potential to more realistically simulate the dynamics of spinal segments and whole spine, and study the effects on spinal elements.

scholarly journals Six-DOF CFD Simulations of Underwater Vehicle Operating Underwater Turning Maneuvers

2021 ◽  
Vol 9 (12) ◽  
pp. 1451
Author(s):  
Kunyu Han ◽  
Xide Cheng ◽  
Zuyuan Liu ◽  
Chenran Huang ◽  
Haichao Chang ◽  
...  
Keyword(s):  
Great Influence ◽  
Underwater Vehicle ◽  
The Body ◽  
Body Motion ◽  
Thrust Distribution ◽  
Turning Motion ◽  
Computational Fluid Dynamics Cfd ◽  
Six Dof ◽  
Cfd Method ◽  
Multi Body

Maneuverability, which is closely related to operational performance and safety, is one of the important hydrodynamic properties of an underwater vehicle (UV), and its accurate prediction is essential for preliminary design. The purpose of this study is to analyze the turning ability of a UV while rising or submerging; the computational fluid dynamics (CFD) method was used to numerically predict the six-DOF self-propelled maneuvers of submarine model BB2, including steady turning maneuvers and space spiral maneuvers. In this study, the overset mesh method was used to deal with multi-body motion, the body force method was used to describe the thrust distribution of the propeller at the model scale, and the numerical prediction also included the dynamic deflection of the control planes, where the command was issued by the autopilot. Then, this study used the published model test results of the tank to verify the effectiveness of the CFD prediction of steady turning maneuvers, and the prediction of space spiral maneuvers was carried out on this basis. The numerical results show that the turning motion has a great influence on the depth and pitch attitude of the submarine, and a “stern heavier” phenomenon occurs to a submarine after steering. The underwater turning of a submarine can not only reduce the speed to brake but also limit the dangerous depth. The conclusion is of certain reference significance for submarine emergency maneuvers.

Chaos in body–vortex interactions

2010 ◽  
Vol 466 (2119) ◽  
pp. 1871-1891 ◽  
Author(s):  
Johan Roenby ◽  
Hassan Aref
Keyword(s):  
Body Shape ◽  
Mass Density ◽  
Relative Equilibrium ◽  
Large Body ◽  
Point Vortex ◽  
Cylindrical Body ◽  
The Body ◽  
Body Motion ◽  
Single Vortex ◽  
Vortex Interactions

The model of body–vortex interactions, where the fluid flow is planar, ideal and unbounded, and the vortex is a point vortex, is studied. The body may have a constant circulation around it. The governing equations for the general case of a freely moving body of arbitrary shape and mass density and an arbitrary number of point vortices are presented. The case of a body and a single vortex is then investigated numerically in detail. In this paper, the body is a homogeneous, elliptical cylinder. For large body–vortex separations, the system behaves much like a vortex pair regardless of body shape. The case of a circle is integrable. As the body is made slightly elliptic, a chaotic region grows from an unstable relative equilibrium of the circle-vortex case. The case of a cylindrical body of any shape moving in fluid otherwise at rest is also integrable. A second transition to chaos arises from the limit between rocking and tumbling motion of the body known in this case. In both instances, the chaos may be detected both in the body motion and in the vortex motion. The effect of increasing body mass at a fixed body shape is to damp the chaos.

scholarly journals Small changes in ball position at address cause a chain effect in golf swing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sung Eun Kim ◽  
Jangyun Lee ◽  
Sae Yong Lee ◽  
Hae-Dong Lee ◽  
Jae Kun Shim ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
Reaction Force ◽  
Statistical Parametric Mapping ◽  
Golf Swing ◽  
Whole Body ◽  
Centre Of Mass ◽  
Body Segment ◽  
A Chain ◽  
Professional Golfers ◽  
The Right

AbstractThe purpose of this study was to investigate how the ball position along the mediolateral (M-L) direction of a golfer causes a chain effect in the ground reaction force, body segment and joint angles, and whole-body centre of mass during the golf swing. Twenty professional golfers were asked to complete five straight shots for each 5 different ball positions along M-L: 4.27 cm (ball diameter), 2.14 cm (ball radius), 0 cm (reference position at preferred ball position), – 2.14 cm, and – 4.27 cm, while their ground reaction force and body segment motions were captured. The dependant variables were calculated at 14 swing events from address to impact, and the differences between the ball positions were evaluated using Statistical Parametric Mapping. The left-sided ball positions at address showed a greater weight distribution on the left foot with a more open shoulder angle compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. These trends disappeared during the backswing and reappeared during the downswing. The whole-body centre of mass was also located towards the target for the left-sided ball positions throughout the golf swing compared to the reference ball position, whereas the trend was reversed for the right-sided ball positions. We have concluded that initial ball position at address can cause a series of chain effects throughout the golf swing.

scholarly journals Validation method for body-mounted sensor attachments

2020 ◽  
Vol 6 (2) ◽  
Author(s):  
Katharina Schmidt ◽  
David Hochmann
Keyword(s):  
Evaluation Method ◽  
Tracking System ◽  
The Body ◽  
Exploratory Research ◽  
Body Segment ◽  
Validation Method ◽  
Sensor Position ◽  
Validation Parameters ◽  
Measurement Units ◽  
Soft Tissue Artifact

AbstractSmall sensor devices like inertial measurement units enable mobile movement and gait analysis, whereby existing systems differ in data acquisition, data processing, and gait parameter calculation. Concerning the validation, recent studies focus on the captured motion and the influence of sensor positioning with respect to the accuracy of the computed biomechanical parameters in comparison to a reference system. Although soft tissue artifact is a major source of error for skin-mounted sensors, there are no investigations regarding the relative movement between the body segment and sensor attachment itself. The aim of this study is to find an evaluation method and to determine parameters that allow the validation of various sensor attachment types and different sensor positionings. The analysis includes the comparison between an adhesive and strap attachment variant as well as the frontal and lateral sensor placement. To validate different attachments, an optical marker-based tracking system was used to measure the body segment and sensor position during movement. The distance between these two positions was calculated and analyzed to determine suitable validation parameters. Despite the exploratory research, the results suggest a feasible validation method to detect differences between the attachments, independent of the sensor type. To have representative and statistically validated results, further studies that involve more participants are necessary.

scholarly journals Self-rechargeable cardiac pacemaker system with triboelectric nanogenerators

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hanjun Ryu ◽  
Hyun-moon Park ◽  
Moo-Kang Kim ◽  
Bosung Kim ◽  
Hyoun Seok Myoung ◽  
...  
Keyword(s):  
Medical Devices ◽  
Mechanical Energy ◽  
Cardiac Pacemaker ◽  
Operation Time ◽  
Lithium Ion ◽  
The Body ◽  
Body Motion ◽  
Triboelectric Nanogenerator ◽  
Implantable Medical Devices ◽  
Energy Harvesters

AbstractSelf-powered implantable devices have the potential to extend device operation time inside the body and reduce the necessity for high-risk repeated surgery. Without the technological innovation of in vivo energy harvesters driven by biomechanical energy, energy harvesters are insufficient and inconvenient to power titanium-packaged implantable medical devices. Here, we report on a commercial coin battery-sized high-performance inertia-driven triboelectric nanogenerator (I-TENG) based on body motion and gravity. We demonstrate that the enclosed five-stacked I-TENG converts mechanical energy into electricity at 4.9 μW/cm3 (root-mean-square output). In a preclinical test, we show that the device successfully harvests energy using real-time output voltage data monitored via Bluetooth and demonstrate the ability to charge a lithium-ion battery. Furthermore, we successfully integrate a cardiac pacemaker with the I-TENG, and confirm the ventricle pacing and sensing operation mode of the self-rechargeable cardiac pacemaker system. This proof-of-concept device may lead to the development of new self-rechargeable implantable medical devices.

A Parametric Study of Low-Frequency Damping of Mooring System

2014 ◽  
Author(s):  
Minglu Chen ◽  
Shan Huang ◽  
Nigel Baltrop ◽  
Ji Chunyan ◽  
Liangbi Li
Keyword(s):  
Low Frequency ◽  
Structure Design ◽  
The Body ◽  
Body Motion ◽  
Mooring Line ◽  
Offshore Structure ◽  
Frequency Oscillation ◽  
Low Frequency Oscillation ◽  
Line System ◽  
Irregular Wave

Mooring line damping plays an important role to the body motion of moored floating platforms. Meanwhile, it can also make contributions to optimize the mooring line system. Accurate assessment of mooring line damping is thus an essential issue for offshore structure design. However, it is difficult to determine the mooring line damping based on theoretical methods. This study considers the parameters which have impact on mooring-induced damping. In the paper, applying Morison formula to calculate the drag and initial force on the mooring line, its dynamic response is computed in the time domain. The energy dissipation of the mooring line due to the viscosity was used to calculate mooring-induced damping. A mooring line is performed with low-frequency oscillation only, the low-frequency oscillation superimposed with regular and irregular wave-frequency motions. In addition, the influences of current velocity, mooring line pretension and different water depths are taken into account.

A Semi-Autonomous Quadruped Robot for Performing Disinfection in Cluttered Environments

2021 ◽  
Author(s):  
Yiyu Chen ◽  
Abhinav Pandey ◽  
Zhiwei Deng ◽  
Anthony Nguyen ◽  
Ruiqi Wang ◽  
...  
Keyword(s):  
Vision System ◽  
Quadruped Robot ◽  
Simulation Software ◽  
The Body ◽  
Body Motion ◽  
Daily Routine ◽  
Public And Private ◽  
Cluttered Environments ◽  
Integrated Simulation ◽  
Human Labor

Abstract The global COVID-19 pandemic has inevitably made disinfection a daily routine to ensure the safety of public and private spaces. However, the existing disinfection procedures are time-consuming and require intensive human labor to apply chemical-based disinfectant onto contaminated surfaces. In this paper, a robot disinfection system is presented to increase the automation of the disinfection task to assist humans in performing routine disinfection safely and efficiently. This paper presents a semi-autonomous quadruped robot called LASER-D for performing disinfection in cluttered environments. The robot is equipped with a spray-based disinfection system and leverages the body motion to control the spray action without an extra stabilization mechanism. The spraying unit is mounted on the robot’s back and controlled by the robot computer. The control architecture is designed based on force control, resulting in navigating rough terrains and the flexibility in controlling the body motion during standing and walking for the disinfection task. The robot also uses the vision system to improve localization and maintain desired distance to the disinfection surface. The system incorporates image processing capability to evaluate disinfected regions with high accuracy. This feedback is then used to adjust the disinfection plan to guarantee that all assigned areas are disinfected properly. The system is also equipped with highly integrated simulation software to design, simulate and evaluate disinfection plans effectively. This work has allowed the robot to successfully carry out effective disinfection experiments while safely traversing through cluttered environments, climb stairs/slopes, and navigate on slippery surfaces.

The Global Motion of a Rigid Body Subject to Periodic Body-Fixed Torques

1995 ◽  
Author(s):  
X. Tong ◽  
B. Tabarrok
Keyword(s):  
Rigid Body ◽  
Equations Of Motion ◽  
Melnikov Method ◽  
The Body ◽  
Body Motion ◽  
Heteroclinic Orbits ◽  
Coordinate Frame ◽  
Global Motion ◽  
Stable And Unstable Manifolds ◽  
Body Subject

Abstract In this paper the global motion of a rigid body subject to small periodic torques, which has a fixed direction in the body-fixed coordinate frame, is investigated by means of Melnikov’s method. Deprit’s variables are introduced to transform the equations of motion into a form describing a slowly varying oscillator. Then the Melnikov method developed for the slowly varying oscillator is used to predict the transversal intersections of stable and unstable manifolds for the perturbed rigid body motion. It is shown that there exist transversal intersections of heteroclinic orbits for certain ranges of parameter values.

LIKE TRAJECTORIES OF THE BODY MOTION IN THE MEDIUM, THE RESISTANCE OF WHICH IS PROPORTIONAL TO THE SQUARE OF RELATIVE VELOCITY

2020 ◽  
pp. 77-83
Author(s):  
A.Y. Peretyatko ◽  
Keyword(s):  
Relative Velocity ◽  
The Body ◽  
Body Motion ◽  
Huge Number ◽  
History Of ◽  
Number Of Publications

For the pre-revolutionary Don historiography, complaints about the lack of a full-fledged generalizing work of the history of the Cossacks were extremely characteristic. As shown in the article, a similar situation is observed in our time: the article has again become the main genre of Cossack historiography, and the understanding of a huge number of publications on the history of various Cossack troops is extremely difficult. The author proves that in these conditions, works that claim to generalize become especially important, but it is extremely difficult to summarize all the facts, developments and research concepts on any broad topic of Cossack history. In his opinion, the search for other methods of scientific generalization and perception by historians of the developments of their colleagues looks promising. One of these ways he sees the organization of round tables on specifically Cossack topics, especially dedicated to new discoveries.

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