scholarly journals Physics of martial arts: Incorporation of angular momentum to model body motion and strikes

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0255670
Author(s):  
Alexis Merk ◽  
Andrew Resnick
Keyword(s):  
Angular Momentum ◽  
Classroom Environment ◽  
Martial Arts ◽  
Kinematic Model ◽  
Time Lapse ◽  
The Body ◽  
Body Motion ◽  
Deformable Solid ◽  
Mechanics Model ◽  
Improved Model

We develop a physics-based kinematic model of martial arts movements incorporating rotation and angular momentum, extending prior analyses. Here, our approach is designed for a classroom environment; we begin with a warm-up exercise introducing counter-intuitive aspects of rotational motion before proceeding to a set of model collision problems that are applied to martial arts movements. Finally, we develop a deformable solid-body mechanics model of a martial arts practitioner suitable for an intermediate mechanics course. We provide evidence for our improved model based on calculations from biomechanical data obtained from prior reports as well as time-lapse images of several different kicks. In addition to incorporating angular motion, our model explicitly makes reference to friction between foot and ground as an action-reaction pair, showing that this interaction provides the motive force/torque for nearly all martial arts movements. Moment-of-inertia tensors are developed to describe kicking movements and show that kicks aimed high, towards the head, transfer more momentum to the target than kicks aimed lower, e.g. towards the body.

scholarly journals A novel six-legged walking machine tool for in-situ operations

2020 ◽  
Vol 15 (3) ◽  
pp. 351-364
Author(s):  
Jimu Liu ◽  
Yuan Tian ◽  
Feng Gao
Keyword(s):  
Machine Tool ◽  
Motion Planning ◽  
Kinematic Model ◽  
The Body ◽  
Body Motion ◽  
Walking Distance ◽  
Walking Machine ◽  
Planning Scheme ◽  
Increasing Demand

Abstract The manufacture and maintenance of large parts in ships, trains, aircrafts, and so on create an increasing demand for mobile machine tools to perform in-situ operations. However, few mobile robots can accommodate the complex environment of industrial plants while performing machining tasks. This study proposes a novel six-legged walking machine tool consisting of a legged mobile robot and a portable parallel kinematic machine tool. The kinematic model of the entire system is presented, and the workspace of different components, including a leg, the body, and the head, is analyzed. A hierarchical motion planning scheme is proposed to take advantage of the large workspace of the legged mobile platform and the high precision of the parallel machine tool. The repeatability of the head motion, body motion, and walking distance is evaluated through experiments, which is 0.11, 1.0, and 3.4 mm, respectively. Finally, an application scenario is shown in which the walking machine tool steps successfully over a 250 mm-high obstacle and drills a hole in an aluminum plate. The experiments prove the rationality of the hierarchical motion planning scheme and demonstrate the extensive potential of the walking machine tool for in-situ operations on large parts.

scholarly journals Application of the Craig-Bampton method to blade rotation

2021 ◽  
Vol 258 ◽  
pp. 09075
Author(s):  
Jose Leoro ◽  
Vladislav Borisenko ◽  
Egor Degilevich ◽  
Anton Didenko
Keyword(s):  
Computing Time ◽  
Large Body ◽  
Element Model ◽  
Practical Experience ◽  
The Body ◽  
Body Motion ◽  
Deformable Solid ◽  
Engineering Software ◽  
Blade Rotation ◽  
Computational Resources

The Craig-Bampton method has repeatedly shown its effectiveness in modelling the deformable solid body motion and in practical experience of implementing this approach in engineering software. It reduces the motion equations system which is obtained by approximating small elastic displacements of the body finite element model with a set of acceptable modes. The application of this method in engineering improves the computing time performance and requires less computational resources. In this article the effectiveness of using the Craig-Bampton method for the blade rotation is evaluated. The need to consider the inertial relationship between large body displacements and elastic deformations was investigated. As a result of the numerical solution, it was obtained that the method works correctly for the investigated task. It allows us to conclude that the Craig-Bampton method is applicable for the blade rotation process.

scholarly journals Digital Biomimetic Architecture between Art and Dynamic Structure: Case Study—Wings in Flight

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Shi-Yen Wu ◽  
Felicia Wagiri ◽  
Yen-Fen Huang ◽  
Shen-Guan Shih
Keyword(s):  
Dynamic Structure ◽  
Time Lapse ◽  
The Body ◽  
Digital Design ◽  
Body Motion ◽  
Advanced Technology ◽  
Alternative Position ◽  
The Aesthetic ◽  
Dynamic Structures ◽  
Over Time

Architecture as a multirelated field is influenced and connected by many subjects. Among those subjects, the role of art and natural science is the most dominant frame without ignoring the development of advanced technology. By using technology, the impossible becomes possible such as to capture the body motion of humans as the subject of art and science at the same time. Body motion is a potential research of movement over the time. This does not only involve the aesthetic, but also even more the scientific aspect of a dynamic motion of an organism that can be investigated through a biomimetic approach. In order to understand the biomimetic term, we investigated the physical morphogenesis and geometrical principle of an organism. The term morphogenesis is a process in which the natural system produces and regulates the configuration of a material in space and over time. Based on that, we tried to design a dynamic structure using butterfly’s motion as a subject of study with morphological and biomimetic approaches. Butterflies show a simultaneous aspect of movement over time characterized by fragmentation. This idea also summarizes many aspects of modern art such as portrayal of body movements by futurists, space-time continuum, cinematic freeze frame, and time-lapse photography. A futurist represents a movement that is emphasized on the factors of speed, technology, modernisms, and objects. This indicates an alternative position that may be relevant to the system of butterfly wings. This can only be achieved by utilizing a digital design and its parametric tools that help generate functions and form dynamic structures with high complexity and precision. Throughout the development of the system, there will be many changes to the form which will be constantly tested and evaluated using a series of prototype and visual digital design.

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 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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