scholarly journals Wireless Manipulation Mechanism and Analysis for Actively Assistive Pinch Movements

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6216
Author(s):  
Dong-Min Ji ◽  
Won-Suk Jung ◽  
Sung-Hoon Kim
Keyword(s):  
Index Finger ◽  
3D Printer ◽  
Hand Rehabilitation ◽  
Rubber Sheet ◽  
Driving System ◽  
Magnetic Forces ◽  
Mechanical Elements ◽  
Training Exercises ◽  
Finger Model ◽  
The Magnetic Field

Pinching motions are important for holding and retaining objects with precision. Therefore, training exercises for the thumb and index finger are extremely important in the field of hand rehabilitation. Considering the need for training convenience, we developed a device and a driving system to assist pinching motions actively via a lightweight, simple, and wireless mechanism driven by the magnetic forces and torques generated by magnets attached to the tip of these two fingers. This device provides accurate pinching motions through the linking structures connecting the two magnets. The fabricated device has minimal mechanical elements with an ultralightweight of 57.2 g. The magnetic field, the intensity of which is based on the time variant, generates a pinching motion between the thumb and index finger, thus rendering it possible to achieve repetitive training. To verify the generation of an active pinching motion, we fabricated a finger model using a 3D printer and a rubber sheet and observed the active motions generated by the newly developed device. We also verified the performance of the proposed mechanism and driving method via various experiments and magnetic simulations. The proposed mechanism represents an important breakthrough for patients requiring hand rehabilitation and wearable assistive motion devices.

scholarly journals Dynamical Galactic Halos

1993 ◽  
Vol 157 ◽  
pp. 415-419
Author(s):  
D. Breitschwerdt ◽  
H.J. Völk ◽  
V. Ptuskin ◽  
V. Zirakashvili
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
The Other ◽  
Galactic Rotation ◽  
Galactic Halos ◽  
Magnetic Forces ◽  
Dynamical Coupling ◽  
Field Lines ◽  
The Magnetic Field ◽  
Open Magnetic Field

It is argued that the description of the magnetic field in halos of galaxies should take into account its dynamical coupling to the other major components of the interstellar medium, namely thermal plasma and cosmic rays (CR's). It is then inevitable to have some loss of gas and CR's (galactic wind) provided that there exist some “open” magnetic field lines, facilitating their escape, and a sufficient level of self-generated waves which couple the particles to the gas. We discuss qualitatively the topology of the magnetic field in the halo and show how galactic rotation and magnetic forces can be included in such an outflow picture.

scholarly journals A First Optimal Control Solution for a Complex, Nonlinear, Tendon Driven Neuromuscular Finger Model

2010 ◽  
Author(s):  
Evangelos A. Theodorou ◽  
Emo Todorov ◽  
Francisco J. Valero-Cuevas
Keyword(s):  
Optimal Control ◽  
Muscle Force ◽  
Index Finger ◽  
Feedback Controller ◽  
Extensor Mechanism ◽  
High Dimensionality ◽  
Control Solution ◽  
Force Velocity ◽  
Finger Model ◽  
Robust To Noise

In this work we present the first constrained stochastic optimal feedback controller applied to a fully nonlinear, tendon driven index finger model. Our model also takes into account an extensor mechanism, and muscle force-length and force-velocity properties. We show this feedback controller is robust to noise and perturbations to the dynamics, while successfully handling the nonlinearities and high dimensionality of the system. By extending prior methods, we are able to approximate physiological realism by ensuring positivity of neural commands and tendon tensions at all times.

A general method for calculating the self-induced magnetic force of an axisymmetric toroidal current

1984 ◽  
Vol 31 (3) ◽  
pp. 415-421
Author(s):  
S. Bobbio ◽  
G. Rubinacci
Keyword(s):  
Approximate Formula ◽  
Magnetic Force ◽  
The Self ◽  
Large Aspect Ratio ◽  
Magnetic Forces ◽  
Correct Calculation ◽  
Peripheral Surface ◽  
Ratio Limit ◽  
The Magnetic Field ◽  
General Method

A method is presented for computing the class of axisymmetric current distributions flowing in a torus whose peripheral surface is a flux surface for the magnetic field produced by the current itself. The method allows the correct calculation of the ‘self-induced’ magnetic forces arising from the interaction between these currents and their own field. The general expression for the self-induced force is given and an approximate formula is presented in the large aspect-ratio limit.

Kinematic Study of a Soft-and-Rigid Robotic Digit for Rehabilitation and Assistive Applications

2016 ◽  
Author(s):  
Mahdi Haghshenas-Jaryani ◽  
Wei Carrigan ◽  
Muthu B. J. Wijesundara ◽  
Rita M. Patterson ◽  
Nicoleta Bugnariu ◽  
...  
Keyword(s):  
Range Of Motion ◽  
Index Finger ◽  
Proper Function ◽  
Kinematic Parameters ◽  
Hand Rehabilitation ◽  
Molding Process ◽  
Center Of Rotation ◽  
Kinematic Study ◽  
Pip Joint ◽  
Human Finger

This paper presents the kinematic study of a pneumatically actuated soft-and-rigid robotic digit designed to be used in exoskeleton-based hand rehabilitation and assistive applications. The soft-and-rigid robotic digit is comprised of three inflatable bellow-shaped structure sections (soft sections) and four semi-rigid sections in an alternating order which correspond to the anatomy of a human finger. The forward and backward bending motions at each soft section (joint) are generated by pressure and vacuum actuation, respectively. The goal here is to investigate the compatibility of the soft robotic digit’s kinematic parameters such as range of motion, center of rotation, and lengthening at the joints with the required anatomical motion of the human finger to ensure proper function and safe interaction. The soft robotic digits were fabricated using silicone rubber materials in a compression molding process for the experimental study. The kinematic parameters of both a human and soft robotic index finger were measured using a motion capture system. The obtained results show that the robotic digit was able to provide the required range of motion: 0–90° at the metacarpophalangeal (MCP) joint, 0–100° at the proximal interphalangeal (PIP) joint, and 0–70° at the distal interphalangeal (DIP) joint. Furthermore, the data show the center of rotation of each soft section (robotic joint) was remotely coincident with that of the corresponding index finger. The lengthening of the three soft sections of the robotic digit were measured to be 7mm, 7mm, and 2mm for the MCP, PIP, and DIP, respectively. The corresponding values for the dorsal skin lengthening of a human index finger is 11mm, 15mm, and 5mm and are longer than the achieved lengthening in the robotic digit.

The magneto-hydrodynamics of a rotating fluid and the earth’s dynamo problem

1963 ◽  
Vol 274 (1357) ◽  
pp. 274-283 ◽  
Keyword(s):  
Magnetic Force ◽  
Necessary Conditions ◽  
Fluid Velocity ◽  
Rotating Fluid ◽  
Rigid Boundary ◽  
Viscous Forces ◽  
Magnetic Forces ◽  
The Earth ◽  
The Magnetic Field

This paper discusses a rotating, incompressible fluid enclosed within a rigid boundary which is a surface of revolution. It is shown that if viscous forces are negligible, then, in the presence of magnetic fields, the fluid can execute slow, steady relative motions only if the magnetic force satisfies a constraint. In cylindrical polar co-ordinates this constraint can be written that is, the couple exerted by the magnetic forces on any cylinder of fluid coaxial with the axis of rotation must vanish. Furthermore, subject to certain restrictions on the shape of the container (which, for example, are fulfilled by a sphere but not by a cylinder), it is shown that if the field satisfies the above condition then the fluid velocity is completely determined by the instantaneous value of the magnetic field (together with that of the density if buoyancy forces are important). This velocity is such that the necessary conditions on the field will continue to be satisfied. An algorithm for the determination of the velocity is given and its application to the earth ’s dynamo problem is indicated.

scholarly journals Self-magnetic field calculations in ray-tracing codes

2000 ◽  
Vol 18 (4) ◽  
pp. 601-610 ◽  
Author(s):  
STANLEY HUMPHRIES ◽  
JOHN PETILLO
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Ray Tracing ◽  
Field Calculation ◽  
Two Dimensional ◽  
Magnetic Forces ◽  
Iteration Cycle ◽  
Simple Rules ◽  
The Magnetic Field ◽  
Limited Accuracy

Beam-generated magnetic fields strongly influence the behavior of relativistic electron guns. Existing methods used in ray-tracing codes have limited accuracy and may not correctly represent nonlaminar beams. We describe a technique for the magnetic field calculation in a two-dimensional code based on the assignment of particle currents to the faces of elements in the mesh used for the electrostatic calculation. The balanced calculation of electric and magnetic forces in the same iteration cycle reduces the possibility of numerical filamentation instabilities. With simple rules of assignment on boundary faces, the method also handles field contributions of electrode currents. Several benchmark calculations performed on conformal meshes illustrate the versatility of the technique.

Hydrodynamics and Warmth Trade in Cycles of Cooling of an Attractive Plate in an Attractive Fluid in the Attractive Field

2021 ◽  
Vol 19 (11) ◽  
pp. 32-39
Author(s):  
S.A.A. Alsaati ◽  
Qasim Shakir Kadhim ◽  
Maher Hassan Rashid ◽  
Tuqa Mohammed Jawad Abd UlKadhim
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Exchange ◽  
Cooling Rate ◽  
Steel Plate ◽  
Lower Intensity ◽  
Transfer Processes ◽  
Magnetic Forces ◽  
Air Cavities ◽  
The Magnetic Field

The effect of the magnetic field on heat transfer processes of a magnetized steel plate cooled in a magnetic fluid is experimentally studied. Thermocouples were installed at six points on the surface of the plate along its length. The plots of temperature versus time are obtained in the absence of a magnetic field and in magnetic fields of different intensity. It is found that the intensity of heat exchange depends to a large extent on the magnitude of the magnetic field and on the location of points on the surface of the plate. In a magnetic field, cooling of the central part of the plate occurs with the same intensity as in the absence of a magnetic field and with a lower intensity in comparison with other points on the surface of the plate. Near the plate ends, the cooling rate of the surface is much greater in the magnetic field than in the absence of it. With increasing magnetic field strength, the cooling rate of points in the central part of the plate decreases and is less than in the absence of a magnetic field. The dependence of heat transfer on the magnitude of the magnetic field is explained by the distribution of the magnetic forces acting on the liquid surrounding the plate and the nature of the vapor-air cavities formed near its surface. Experiments on simulation of formation and the shape of vapor-air cavities in a liquid surrounding a magnetizing plate are described.

scholarly journals Distribution of the Magnetic Force in the Surface Layers of Sunspots

1971 ◽  
Vol 43 ◽  
pp. 505-511
Author(s):  
J. Jakimiec
Keyword(s):  
Magnetic Field ◽  
Magnetic Force ◽  
Vertical Structure ◽  
Three Dimensional ◽  
Suitable Method ◽  
Surface Layers ◽  
Magnetic Forces ◽  
Photospheric Level ◽  
The Magnetic Field

At the beginning the problem of constructing the three-dimensional magnetohydrostatic models of the photospheric layers in sunspots is discussed in some detail. It is pointed out that the construction of such models by solving the set of equations of magnetohydrostatics cannot be effectively carried out.In order to solve the difficulties a suitable method of determining the distribution of the magnetic force in sunspots from measurements of the magnetic field has been worked out. Tentative results of the computations are presented.General features of the distribution of the magnetic force in the photospheric layers of stable sunspots are discussed. It is pointed out that significant magnetic forces are necessary in the penumbra; they secure its transversal equilibrium, but are rather unimportant for its vertical structure. And it is quite probable that the magnetic field in the umbras of stable spots is nearly potential or force-free down to the photospheric level.

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