Open-loop speed calculation in stator-fixed reference frame

2007 ◽  
Vol 6 (2) ◽  
pp. 125-130
Author(s):  
M. Németh-Csóka
Keyword(s):  
Reference Frame ◽  
Open Loop ◽  
Fixed Reference

A Neural Network Model of Flexible Spatial Updating

2004 ◽  
Vol 91 (4) ◽  
pp. 1608-1619 ◽  
Author(s):  
Robert L. White ◽  
Lawrence H. Snyder
Keyword(s):  
Neural Network ◽  
Reference Frame ◽  
Spatial Information ◽  
Target Location ◽  
Target Position ◽  
Spatial Location ◽  
Spatial Updating ◽  
Gaze Shift ◽  
Fixed Reference ◽  
Gaze Position

Neurons in many cortical areas involved in visuospatial processing represent remembered spatial information in retinotopic coordinates. During a gaze shift, the retinotopic representation of a target location that is fixed in the world (world-fixed reference frame) must be updated, whereas the representation of a target fixed relative to the center of gaze (gaze-fixed) must remain constant. To investigate how such computations might be performed, we trained a 3-layer recurrent neural network to store and update a spatial location based on a gaze perturbation signal, and to do so flexibly based on a contextual cue. The network produced an accurate readout of target position when cued to either reference frame, but was less precise when updating was performed. This output mimics the pattern of behavior seen in animals performing a similar task. We tested whether updating would preferentially use gaze position or gaze velocity signals, and found that the network strongly preferred velocity for updating world-fixed targets. Furthermore, we found that gaze position gain fields were not present when velocity signals were available for updating. These results have implications for how updating is performed in the brain.

scholarly journals On Manipulation of Objects in Three-Fingered Grasp

1995 ◽  
Vol 117 (4) ◽  
pp. 561-565 ◽  
Author(s):  
D. P. Chevallier ◽  
S. Payandeh
Keyword(s):  
Reference Frame ◽  
New Method ◽  
Inner Product ◽  
Product Spaces ◽  
End Effector ◽  
Inner Product Spaces ◽  
Contact Points ◽  
Fixed Reference ◽  
Fine Manipulation

Manipulation of the grasped object is defined as the ability of the mechanical end-effector to create an instantaneous motion of the object with respect to a fixed reference frame (e.g., palm reference frame). This class of manipulation is usually referred to as the fine manipulation whereas a collection of all these instantaneous motions of the object is referred to as the gross manipulation. This paper presents a new method where for a given desired twist of the grasped object, the instantaneous motions of the fingertips can be determined. The results of the paper are divided into two parts. First, for the case where the motion of the object is created through motions of the fingertip in off-tangent planes to the object at the contact points. Second, where a class of motion of the grasped object is achieved through motions of the fingertips which are restricted to the tangent planes. The method of this paper utilizes screw geometry, inner product spaces and information regarding grasp configuration. The method is also illustrated through examples.

scholarly journals Dynamics of an Artificial Satellite in an Earth-Fixed Reference Frame: Effects of Polar Motions

1980 ◽  
Vol 56 ◽  
pp. 271-274
Author(s):  
P. Farinella ◽  
A. Milani ◽  
A.M. Nobili ◽  
F. Sacerdote
Keyword(s):  
Reference Frame ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Earth Satellite ◽  
Unknown Parameters ◽  
Fixed Frame ◽  
Long Period ◽  
Fixed Reference ◽  
Orbital Data ◽  
Free Nutation

AbstractIn an Earth-fixed reference frame, polar motions (precession, lunisolar nutation, free nutation) introduce small apparent forces in the equations of motion of an Earth satellite. We discuss the possibilities (a) of integrating the orbit in an Earth-fixed frame when tracking data are used for geophysical applications, and (b) of determining from orbital data a set of unknown parameters describing the long-period wandering of the pole.

Fixed-Reference-Frame Phase-Locked Loop for Grid Synchronization Under Unbalanced Operation

2011 ◽  
Vol 58 (5) ◽  
pp. 1943-1951 ◽  
Author(s):  
Gerardo Escobar ◽  
Misael F. Martinez-Montejano ◽  
Andres A. Valdez ◽  
Panfilo R. Martinez ◽  
Michael Hernandez-Gomez
Keyword(s):  
Reference Frame ◽  
Phase Locked Loop ◽  
Grid Synchronization ◽  
Fixed Reference

A Technical Note on the appropriate CFD boundary conditions for the prediction of ground effect aerodynamics

1999 ◽  
Vol 103 (1029) ◽  
pp. 545-547 ◽  
Author(s):  
T. J. Barber ◽  
E. Leonardi ◽  
R. D. Archer
Keyword(s):  
Reference Frame ◽  
Real Life ◽  
Ground Effect ◽  
Technical Note ◽  
Wind Tunnel Testing ◽  
Life Situation ◽  
Moving Vehicle ◽  
Real Life Situation ◽  
Fixed Reference ◽  
Computational Fluid Dynamics Cfd

The accurate prediction of ground effect aerodynamics is an important aspect of wing-in-ground effect vehicle (WIG) design. Computational fluid dynamics (CFD) solutions are useful alternatives to expensive (especially in the case of ground effect) wind-tunnel testing. However, the incorporation of the rigid surface effects often leads to confusion due to such a model being in a vehicle fixed reference frame (air moving, vehicle fixed) rather than the real-life situation of a ground fixed reference frame (air fixed, vehicle moving).

scholarly journals Pose Changes From a Different Point of View

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
Gregory S. Chirikjian ◽  
Robert Mahony ◽  
Sipu Ruan ◽  
Jochen Trumpf
Keyword(s):  
Rigid Body ◽  
Reference Frame ◽  
Semidirect Product ◽  
Group Structure ◽  
Linear Part ◽  
Point Of View ◽  
Affine Transformations ◽  
Fixed Reference ◽  
New Perspective ◽  
Direct Product Group

For more than a century, rigid-body displacements have been viewed as affine transformations described as homogeneous transformation matrices wherein the linear part is a rotation matrix. In group-theoretic terms, this classical description makes rigid-body motions a semidirect product. The distinction between a rigid-body displacement of Euclidean space and a change in pose from one reference frame to another is usually not articulated well in the literature. Here, we show that, remarkably, when changes in pose are viewed from a space-fixed reference frame, the space of pose changes can be endowed with a direct product group structure, which is different from the semidirect product structure of the space of motions. We then show how this new perspective can be applied more naturally to problems such as monitoring the state of aerial vehicles from the ground, or the cameras in a humanoid robot observing pose changes of its hands.

scholarly journals Video analysis using a shaking camera

2021 ◽  
Vol 43 ◽  
Author(s):  
V. L. B. de Jesus ◽  
D. G. G. Sasaki
Keyword(s):  
Fixed Point ◽  
Reference Frame ◽  
Video Analysis ◽  
Analysis Software ◽  
Fixed Reference ◽  
Handheld Camera

To perform a reliable video analysis, it is mandatory to avoid shaking the camera while taking the video, normally using a tripod for smartphones/cameras. But there are some situations which the only chance to make the video is using your hands and it is almost impossible to avoid shaking the camera even trying your best. Imagine the following situation: a volleyball is obliquely launched, and the video is filmed by hand. Then, a point that is fixed in relation to the ground is chosen as the origin of a ground fixed reference frame. Despite being a ground fixed point, it will appear shaky in images captured by the handheld camera. Thereby, two standard video analyses are performed, one from the ground fixed point random shaking and one from the ball’s trajectory, both in relation to the default reference frame of the video analysis software. Lastly, to implement the video analysis of the relative ball movement it is enough to subtract the position coordinates of the ball’s movement by the position coordinates of the ground fixed point tremble, at each instant of time. The graphs of the position and velocity components versus time are presented, and the results are discussed.

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