Non-epipolar rigidity constraint over image-to-image correspondences under paraperspective projection

1997 ◽  
Author(s):  
Ronald Chung
Keyword(s):  
Rigidity Constraint

A Sliding-Mode Control Algorithm to Enhance In-Hand Motion Capabilities

2020 ◽  
Author(s):  
Rajesh Kumar ◽  
Joyjit Mukherjee ◽  
Sudipto Mukherjee
Keyword(s):  
Sliding Mode Control ◽  
Control Algorithm ◽  
Optimization Problems ◽  
Sliding Mode ◽  
Spherical Object ◽  
Relative Slip ◽  
Mode Control ◽  
Rigidity Constraint ◽  
Internal Forces ◽  
Robotic Fingers

Abstract This paper reports a method for regulating the internal forces during in hand manipulation of an unknown shaped object with soft robotic fingers. It is known that for the case of multifingered manipulation, a part of the forces applied by the fingers result in the motion of the object, whereas the other part is considered to be an internal force. The internal forces do not result in the motion of the object but are used to improve the grip on the object. For an object with unknown shape, the internal forces are regulated to ensure that the object does not slip off during manipulation. It is shown that if soft fingers show bounded conformity and the finger-object interface does not have relative slip (or a bounded slip), then the relative angular velocity between the object and the fingertip frame in contact is bounded. The proof is used to define of a new metric of relative slip. The metric is used to design a sliding mode control algorithm. The robotic fingers are assumed to be under virtual rigidity constraint, that is, the distance between the fingers do not change. The control algorithm is attractive as it skirts requirement of information of the shape of the object or to solve optimization problems. The control algorithm developed controls the internal forces and does not require the knowledge of the shape of the object. The methodology is simulated for the case of one spherical object and one conical object.

Bubbly Recessions

2020 ◽  
Vol 12 (4) ◽  
pp. 33-70
Author(s):  
Siddhartha Biswas ◽  
Andrew Hanson ◽  
Toan Phan
Keyword(s):  
Lower Bound ◽  
Wage Rigidity ◽  
Nominal Wage ◽  
Economic Activities ◽  
Financial Friction ◽  
Secular Stagnation ◽  
Trade Off ◽  
Rigidity Constraint ◽  
Ex Ante ◽  
Nominal Wage Rigidity

We develop a tractable bubbles model with financial friction and downward wage rigidity. Competitive speculation in risky bubbles can result in excessive investment booms that precede inefficient busts, where post-bubble aggregate economic activities collapse below the pre-bubble trend. Risky bubbles can reduce ex ante social welfare, and leaning-against-the-bubble policies that balance the boom-bust trade-off can be warranted. We further show that the collapse of a bubble can push the economy into a “secular stagnation” equilibrium, where the zero lower bound and the nominal wage rigidity constraint bind, leading to a persistent recession, such as the Japanese “lost decades.” (JEL E22, E24, E32, E44, L26)

Detecting moving objects using the rigidity constraint

1993 ◽  
Vol 15 (2) ◽  
pp. 162-166 ◽  
Author(s):  
W.B. Thompson ◽  
P. Lechleider ◽  
E.R. Stuck
Keyword(s):  
Moving Objects ◽  
Rigidity Constraint

Ambiguous Pictorial Depth Cues and Perceptions of Nonrigid Motion in the Three-Loop Figure

Perception ◽  
1994 ◽  
Vol 23 (9) ◽  
pp. 1049-1062
Author(s):  
Jack Broerse ◽  
Rongxin Li ◽  
Roderick Ashton
Keyword(s):  
Three Dimensional ◽  
Nonrigid Motion ◽  
Rigid Transformation ◽  
Shape Constancy ◽  
Depth Cues ◽  
Pictorial Depth ◽  
Rigidity Constraint ◽  
Invariance Hypothesis ◽  
Special Instance ◽  
Classical Size

The three-loop figure is a two-dimensional (2-D) pattern that generates (mis)perceptions of nonrigid three-dimensional (3-D) structure when rotated about its centre. Such observations have been described as counterexamples to the principle whereby a moving object is presumed to be rigid, provided that a rigid interpretation is possible (ie the ‘rigidity constraint’). In the present investigation we demonstrated that stationary three-loop figures exhibit many of the classic properties of multistable/ambiguous figures, with any one of several possible 3-D configurations being reported at any one instant. Further investigation revealed that perceived nonrigidity during rotation was markedly reduced (and rigidity enhanced) when the figure was modified with static pictorial depth cues (eg shading, interposition). These cues had no effect on the overall proportion of time that observers reported 3-D organisations in stationary versions of the figure, but significantly reduced the frequency of perceptual reorganisation, and increased the duration for reporting a particular organisation. Since each of the perceived 3-D structures in a stationary ambiguous 2-D figure has a unique kinetic counterpart (ie rigid transformation), we attribute the nonrigid structure perceived when the figure rotates to the integration of these otherwise inconsistent kinetic components; and have further illustrated this with modified versions of a Penrose impossible triangle. Under kinetic versions of the classical size/distance invariance hypothesis, the rigidity constraint may be considered to represent a special instance of size/shape constancy, in which case counterexamples involving (mis)perceptions of nonrigid structure are comparable to other well-known exceptions to such principles of minimum object change (eg classical illusions).

Nonrigid registration using a rigidity constraint

2006 ◽  
Author(s):  
Marius Staring ◽  
Stefan Klein ◽  
Josien P. W. Pluim
Keyword(s):  
Nonrigid Registration ◽  
Rigidity Constraint

scholarly journals HEISENBERG SPINS ON A CYLINDER SECTION

2000 ◽  
Vol 14 (19n20) ◽  
pp. 2093-2100 ◽  
Author(s):  
J. BENOIT ◽  
R. DANDOLOFF ◽  
A. SAXENA
Keyword(s):  
Boundary Conditions ◽  
Finite Length ◽  
Continuum Limit ◽  
Elastic Cylinder ◽  
Physical Realization ◽  
Topological Soliton ◽  
Geometric Effect ◽  
Rigidity Constraint ◽  
Cylinder Model ◽  
The Continuum

Classical Heisenberg spins in the continuum limit (i.e. the nonlinear σ-model) are studied on an elastic cylinder section with homogeneous boundary conditions. The latter may serve as a physical realization of magnetically coated microtubules and cylindrical membranes. The corresponding rigid cylinder model exhibits topological soliton configurations with geometrical frustration due to the finite length of the cylinder section. Assuming small and smooth deformations allows to find shapes of the elastic support by relaxing the rigidity constraint: an inhomogeneous Lamé equation arises. Finally, this leads to a novel geometric effect: a global shrinking of the cylinder section with swellings.

scholarly journals Reduced-order modeling by POD-multiphase approach for fluid-structure interaction

2010 ◽  
pp. 41-52
Author(s):  
Erwan Liberge ◽  
Marie Pomarede ◽  
Aziz Hamdouni
Keyword(s):  
Rigid Body ◽  
High Viscosity ◽  
Reduced Order Modeling ◽  
Weak Formulation ◽  
Reduced Order ◽  
Fixed Domain ◽  
Rigidity Constraint ◽  
Moving Domains ◽  
Reference Domain ◽  
Proper Orthogonal

This paper describes the Reduced Order Modeling (ROM) for fluid rigid body interaction problem and discusses Proper Orthogonal Decomposition (POD) utilisation. The principal difficulty for using POD being the moving domains, a referenced fixed domain has been introduced. The POD has been applied for the velocity field obtained on the fixed domain. Then a method to reduce dynamical system for rigid body fluid interaction has been developed. This method consists in treating the entire fluid-solid domain as a fluid. The rigid body has then been considered as a fluid, by using a high viscosity which can play the role of a penalisation factor of the rigidity constraint. The fluid flow problem is then formulated on the reference domain and POD modes have been used in the weak formulation.

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