An Exact Optimization of Interaction Forces in Three-Fingered Manipulation

1992 ◽  
Vol 114 (1) ◽  
pp. 48-54 ◽  
Author(s):  
S. Mukherjee ◽  
K. J. Waldron
Keyword(s):  
Frictional Contact ◽  
Three Dimensional ◽  
Friction Angle ◽  
Interaction Force ◽  
Dimensional Problem ◽  
Minimum Norm Solution ◽  
Interaction Forces ◽  
Maximum Value ◽  
Solution Field ◽  
Exact Optimization

Manipulation with three fingers in frictional contact is known to be an underspecified problem. The minimum norm solution, also referred to as the equilibrating solution field, can be modified by superimposing a linear combination of the resulting null solutions, called the interaction force field. The modification proposed here, applicable to the three-dimensional problem, minimizes the maximum value of the friction angle at the points of contract. A grasp of maximum possible stability under a set of contact and loading conditions is hence achieved.

Image Forces on 3D Dislocation Structures in Crystals of Finite Volume

1998 ◽  
Vol 538 ◽  
Author(s):  
A. El-Azab
Keyword(s):  
Finite Volume ◽  
Three Dimensional ◽  
Direct Interaction ◽  
Interaction Force ◽  
Infinite Domain ◽  
Range Interaction ◽  
Interaction Forces ◽  
Long Range Interaction ◽  
Order Of Magnitude ◽  
Crystal Volume

AbstractThe present work aims at studying the image stress and image Peach-Koehler force fields for three-dimensional dislocation configurations in a single crystal of finite volume. It is shown that the image stress field is significant within the entire crystal volume, and that the image Peach-Koehler force can be of the same order of magnitude as the direct interaction force calculated from the infinite domain solution. The results demonstrate that image stress gives rise to long-range interaction forces that are important in meso-scale dynamics of dislocation structures.

scholarly journals An Efficient Three-Dimensional Convolutional Neural Network for Inferring Physical Interaction Force from Video

Sensors ◽  
2019 ◽  
Vol 19 (16) ◽  
pp. 3579 ◽  
Author(s):  
Dongyi Kim ◽  
Hyeon Cho ◽  
Hochul Shin ◽  
Soo-Chul Lim ◽  
Wonjun Hwang
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Three Dimensional ◽  
Interaction Force ◽  
Temporal Information ◽  
Video Frame ◽  
Physical Interaction ◽  
Interaction Forces ◽  
Contact Type ◽  
Proposed Model

Interaction forces are traditionally predicted by a contact type haptic sensor. In this paper, we propose a novel and practical method for inferring the interaction forces between two objects based only on video data—one of the non-contact type camera sensors—without the use of common haptic sensors. In detail, we could predict the interaction force by observing the texture changes of the target object by an external force. For this purpose, our hypothesis is that a three-dimensional (3D) convolutional neural network (CNN) can be made to predict the physical interaction forces from video images. In this paper, we proposed a bottleneck-based 3D depthwise separable CNN architecture where the video is disentangled into spatial and temporal information. By applying the basic depthwise convolution concept to each video frame, spatial information can be efficiently learned; for temporal information, the 3D pointwise convolution can be used to learn the linear combination among sequential frames. To validate and train the proposed model, we collected large quantities of datasets, which are video clips of the physical interactions between two objects under different conditions (illumination and angle variations) and the corresponding interaction forces measured by the haptic sensor (as the ground truth). Our experimental results confirmed our hypothesis; when compared with previous models, the proposed model was more accurate and efficient, and although its model size was 10 times smaller, the 3D convolutional neural network architecture exhibited better accuracy. The experiments demonstrate that the proposed model remains robust under different conditions and can successfully estimate the interaction force between objects.

Mathematical Theory of Transversally Isotropic Shells of Arbitrary Thickness at Static Load

2019 ◽  
Vol 968 ◽  
pp. 496-510
Author(s):  
Anatoly Grigorievich Zelensky
Keyword(s):  
Mathematical Theory ◽  
Three Dimensional ◽  
Nonlinear Problems ◽  
Theory Of Elasticity ◽  
Elastic Plates ◽  
Dimensional Problem ◽  
Boundary Problems ◽  
Complex Boundary ◽  
Plates And Shells ◽  
Basic Equations

Classical and non-classical refined theories of plates and shells, based on various hypotheses [1-7], for a wide class of boundary problems, can not describe with sufficient accuracy the SSS of plates and shells. These are boundary problems in which the plates and shells undergo local and burst loads, have openings, sharp changes in mechanical and geometric parameters (MGP). The problem also applies to such elements of constructions that have a considerable thickness or large gradient of SSS variations. The above theories in such cases yield results that can differ significantly from those obtained in a three-dimensional formulation. According to the logic in such theories, the accuracy of solving boundary problems is limited by accepted hypotheses and it is impossible to improve the accuracy in principle. SSS components are usually depicted in the form of a small number of members. The systems of differential equations (DE) obtained here have basically a low order. On the other hand, the solution of boundary value problems for non-thin elastic plates and shells in a three-dimensional formulation [8] is associated with great mathematical difficulties. Only in limited cases, the three-dimensional problem of the theory of elasticity for plates and shells provides an opportunity to find an analytical solution. The complexity of the solution in the exact three-dimensional formulation is greatly enhanced if complex boundary conditions or physically nonlinear problems are considered. Theories in which hypotheses are not used, and SSS components are depicted in the form of infinite series in transverse coordinates, will be called mathematical. The approximation of the SSS component can be adopted in the form of various lines [9-16], and the construction of a three-dimensional problem to two-dimensional can be accomplished by various methods: projective [9, 14, 16], variational [12, 13, 15, 17]. The effectiveness and accuracy of one or another variant of mathematical theory (MT) depends on the complex methodology for obtaining the basic equations.

Simulation of Three-Dimensional Stress Distribution in Compression Dies

2008 ◽  
Vol 575-578 ◽  
pp. 449-454
Author(s):  
Chu Yun Huang ◽  
Sai Yu Wang ◽  
Tao Yang ◽  
Xu Dong Yan
Keyword(s):  
Stress Distribution ◽  
Computer Aided Design ◽  
Three Dimensional ◽  
Distribution Model ◽  
Extrusion Dies ◽  
Maximum Value ◽  
Multiple Unit ◽  
Stress Freezing Method ◽  
Experimental Values ◽  
Aided Design

The stress fields of rectangular and T shape compression dies were simulated by three dimensional photo-elasticity of stress freezing method. The rules of stress distribution of σx, σy, σz on the surface of rectangular and T-shaped dies were discovered, and the rules were also found inside the dies. The results indicate that the stress distribution of rectangular die is similar to that of T shape die. Obvious stress concentration in corner of die hole was observed. σz rises from die hole to periphery until it achieves maximum value then it diminishes gradually, and σz between die hole and fix diameter zone is higher than it is in other position. At the same time, the equations of stress field of extrusion dies were obtained by curved surface fitting experimental values in every observed point with multiple-unit regression analysis method and orthogonal transforms. These works can provide stress distribution model for die computer aided design and make.

Some Remarks on the Behaviour of Surface Source Distributions near the Edge of a Body

1973 ◽  
Vol 24 (1) ◽  
pp. 25-33
Author(s):  
J W Craggs ◽  
K W Mangler ◽  
M Zamir
Keyword(s):  
Flow Direction ◽  
Three Dimensional ◽  
Cross Flow ◽  
Symmetric Case ◽  
The Body ◽  
Dimensional Problem ◽  
Surface Source ◽  
Asymmetric Case ◽  
Main Flow Direction ◽  
Flow Plane

SummaryWhen the incompressible potential flow past a three-dimensional body is represented by source distributions on the body surface, these source distributions have singularities near an edge or corner, for example á trailing edge of a wing or the (unfaired) intersection of a body and a wing. The nature of these singularities is discussed. When assuming slow variations of the geometry in the main flow direction we can consider a two-dimensional problem in the cross-flow plane. Here the tangential velocities and source distributions are proportional to certain powers of the distance from the corner. For example at a convex right-angled corner these powers are − ⅓ in the asymmetric case (the bisector is a potential line) and ⅓ in the symmetric case (the bisector is a streamline) for both sources and tangential velocities. At a concave right-angled corner the corresponding values for the source distributions are ⅓ (asymmetric case) and − ⅓ (symmetric case) whereas they are 1 and 3 respectively for the tangential velocities.

Three-Dimensional Analysis on the Performance of the Thermoelectric Micro-Cooler

2005 ◽  
Author(s):  
Kong Hoon Lee ◽  
Ook Joong Kim
Keyword(s):  
Temperature Difference ◽  
Three Dimensional ◽  
Coefficient Of Performance ◽  
Thermoelectric Cooler ◽  
Small Temperature ◽  
Small Current ◽  
Thermoelectric Element ◽  
Maximum Value ◽  
Column Type ◽  
P Type

Three-dimensional numerical analysis has been carried out using the FEMLAB software package to figure out the performance of the thermoelectric micro-cooler. A small-size and column-type thermoelectric cooler is considered and Bi2Te3 and Sb2Te3 are selected as the n- and p-type thermoelectric materials, respectively. The thickness of the thermoelectric element considered is 5 to 20 μm and the thickness affects the performance of the cooler. The effect of parameters such as the temperature difference, the current, and the thickness of the thermoelectric element on the performance of the cooler has also been investigated. The coefficient of performance (COP) is the primary factor to evaluate the performance of the cooler and the COP varies with the parameters. The COP has the maximum value at a certain current and the value decreases with the temperature difference or the thickness. The predicted results also show that the performance can be improved for thick thermoelectric element at the small temperature difference and small current.

Research about Slider Three-Dimensional Frictional Contact Problem of the Polygonal and Similar-Oval Jib

2013 ◽  
Vol 385-386 ◽  
pp. 85-88
Author(s):  
Shi Lin Shen ◽  
Zhong Peng Zhang ◽  
Bin Gu ◽  
Rong Chen
Keyword(s):  
Boundary Condition ◽  
Stress Distribution ◽  
Traditional Method ◽  
Frictional Contact ◽  
Contact Region ◽  
Three Dimensional ◽  
Supporting Function ◽  
Partial Stability ◽  
Contact Situation ◽  
Actual Response

The existence of boundary condition and friction are difficult to predict which makes the sliders contact situation extremely complex. The actual response of the contact region becomes a tough research by using traditional method. Taking the cylinder supporting function into account, the polygonal and similar-oval Jib models are established. Research of the stress distribution and the stress concentration phenomenon is analyzed. The results indicate that stress distribution of the sliders of the similar-oval Jib is more uniform in comparison with the polygonal Jib that it can ameliorate the stress state of the contact region and enhance the partial stability of the Jib.

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