scholarly journals Automatic Orientation Estimation of Inertial Sensors in C-Arm CT Projections

2019 ◽  
Vol 5 (1) ◽  
pp. 195-198 ◽  
Author(s):  
Mareike Thies ◽  
Jennifer Maier ◽  
Björn Eskofier ◽  
Andreas Maier ◽  
Marc Levenston ◽  
...  
Keyword(s):  
Coordinate System ◽  
Inertial Sensors ◽  
Local Coordinate System ◽  
Three Dimensional ◽  
Ground Truth ◽  
Radial Symmetry ◽  
Sift Algorithm ◽  
Position Data ◽  
Measurement Units ◽  
Three Dimensional Coordinate

AbstractTo obtain CT images of the knee joint in a more lifelike position, data acquisition can be performed with patients in standing rather than in lying position. However, in that situation, people tend to show involuntary motion. One possibility to compensate for that motion is the use of Inertial Measurement Units, that capture the accelerations during the scan. For this purpose, their local coordinate system needs to be known. An estimation based on the SIFT algorithm was implemented and compared to an existing approach that uses the Fast Radial Symmetry transform and to expert labels for evaluation. The SIFT method showed to be superior to the existing approach as it could extract stable feature points from the projections that were used to estimate the three-dimensional coordinate system in a reliable manner. The final algorithm achieved a mean euclidean distance of 2.61 mm between the calculated position of the origin and the assumed ground truth by the expert labels.

Influencing of Coordinate Transformation on Based CGCS2000 on Topographic Map with Large Scales

2014 ◽  
Vol 522-524 ◽  
pp. 1207-1210
Author(s):  
Qing Wu Meng ◽  
Lu Meng
Keyword(s):  
Coordinate System ◽  
Coordinate Transformation ◽  
Grid Point ◽  
Three Dimensional ◽  
Transformation Model ◽  
Topographic Maps ◽  
Topographic Map ◽  
Transformation Parameters ◽  
Coordinate Changes ◽  
Three Dimensional Coordinate

Using three dimensional coordinate transformation model with 7 parameters the coordinate transformation parameters are solved. Comparing the coordinates of the kilometer grid point on topographic maps in Beijing54, Xian80 and Urban Independent Coordinate System with the observation coordinates of same point inCGCS2000, Through watching their coordinate changes the moving changes regularity on topographic maps are discovered between Beijing54 and CGCS2000, between Xian 80 and CGCS2000, Urban Independent Coordinate System and CGCS2000

Chinese Geodetic Coordinate System 2000 and its Comparison with WGS84

2014 ◽  
Vol 580-583 ◽  
pp. 2793-2796 ◽  
Author(s):  
Hou Pu Li ◽  
Shao Feng Bian ◽  
Zhong Mei Li
Keyword(s):  
Coordinate System ◽  
Normal Gravity ◽  
Three Dimensional ◽  
Vertical Gradient ◽  
Coordinate Systems ◽  
Present Measurement ◽  
Three Dimensional Coordinate ◽  
Geodetic Coordinate System ◽  
International Measurement ◽  
Geocentric Coordinate System

It is a general trend to adopt the geocentric coordinate system as a geodetic datum for the international measurement community. The definition and realization of Chinese geocentric three-dimensional coordinate system (CGCS2000) which has been employed since July 1st, 2008 were introduced in detail. The defining parameters and derived constants of the reference ellipsoid used were given. The comparison between CGCS2000 and WGS84 was carried out. The differences of geodetic coordinates of a point between the two coordinate systems, normal gravity and vertical gradient of normal gravity on the two ellipsoids caused by the change of the flattening of the ellipsoid were analyzed. The results show that these differences could be neglected in view of present measurement accuracies.

Three Dimensional Absolute Nodal Coordinate Formulation for Beam Elements: Theory

2000 ◽  
Vol 123 (4) ◽  
pp. 606-613 ◽  
Author(s):  
Ahmed A. Shabana ◽  
Refaat Y. Yakoub
Keyword(s):  
Coordinate System ◽  
Absolute Nodal Coordinate Formulation ◽  
Mass Matrix ◽  
Local Coordinate System ◽  
Three Dimensional ◽  
Deformation Analysis ◽  
Large Element ◽  
Absolute Nodal Coordinate ◽  
Beam Elements ◽  
Highly Nonlinear

The description of a beam element by only the displacement of its centerline leads to some difficulties in the representation of the torsion and shear effects. For instance such a representation does not capture the rotation of the beam as a rigid body about its own axis. This problem was circumvented in the literature by using a local coordinate system in the incremental finite element method or by using the multibody floating frame of reference formulation. The use of such a local element coordinate system leads to a highly nonlinear expression for the inertia forces as the result of the large element rotation. In this investigation, an absolute nodal coordinate formulation is presented for the large rotation and deformation analysis of three dimensional beam elements. This formulation leads to a constant mass matrix, and as a result, the vectors of the centrifugal and Coriolis forces are identically equal to zero. The formulation presented in this paper takes into account the effect of rotary inertia, torsion and shear, and ensures continuity of the slopes as well as the rotation of the beam cross section at the nodal points. Using the proposed formulation curved beams can be systematically modeled.

scholarly journals Periodic orbits in the restricted problem of three bodies in a three-dimensional coordinate system when the smaller primary is a triaxial rigid body

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Awadhesh Kumar Poddar ◽  
Divyanshi Sharma
Keyword(s):  
Perturbation Theory ◽  
Rigid Body ◽  
Coordinate System ◽  
Periodic Orbits ◽  
Restricted Problem ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
General Perturbation ◽  
Triaxial Rigid Body ◽  
Three Dimensional Coordinate

AbstractIn this paper, we have studied the equations of motion for the problem, which are regularised in the neighbourhood of one of the finite masses and the existence of periodic orbits in a three-dimensional coordinate system when μ = 0. Finally, it establishes the canonical set (l, L, g, G, h, H) and forms the basic general perturbation theory for the problem.

THREE-DIMENSIONAL GEOMETRY WITHIN A DRIVING SIMULATOR

2005 ◽  
Vol 16 (06) ◽  
pp. 909-920 ◽  
Author(s):  
T. JANSE VAN RENSBURG ◽  
M. A. VAN WYK ◽  
W.-H. STEEB
Keyword(s):  
Coordinate System ◽  
Programming Language ◽  
Driving Simulator ◽  
Three Dimensional ◽  
Visual Display ◽  
Mathematical Framework ◽  
Coordinate Transformations ◽  
Flight Simulators ◽  
Three Dimensional Coordinate

Three-dimensional coordinate transformations are an essential part of the realistic visual display within a driving simulator. They are also used in other simulators such as flight simulators and for robotics. In this paper, the mathematical framework for implementing three-dimensional coordinate transformations is presented, provided with more detail for implementing it in a programming language such as C++. The realistic positioning of an observer for the "behind and above" view in a driving simulator will be discussed as an application of coordinate system transformations.

scholarly journals Uncertainty Analysis of Three-Dimensional Coordinate Measuring Machines

1997 ◽  
Vol 9 (2) ◽  
pp. 140-145 ◽  
Author(s):  
Jiro Matsuda ◽  
Keyword(s):  
Uncertainty Analysis ◽  
Coordinate System ◽  
Three Dimensional ◽  
Coordinate Measuring Machines ◽  
Uncertainty Of Measurement ◽  
Expanded Uncertainty ◽  
Systematic Experiment ◽  
Orthogonal Coordinate System ◽  
Three Dimensional Coordinate

On the basis of the condition that the distances between planes be measured in accordance with the ISO guide ""Uncertainty of Measurement"", the uncertainty of measurement of a CMM in the orthogonal coordinate system has been obtained by carrying out a systematic experiment. So the expanded uncertainty is given as 4.4μm.

scholarly journals Using a Gauge Block for Derivation of Parameters of Four Laser Triangulation Sensors in a Local Coordinate System

2020 ◽  
Vol 20 (5) ◽  
pp. 210-217
Author(s):  
Ján Buša ◽  
Miroslav Dovica ◽  
Mikhail Zhabitsky
Keyword(s):  
Coordinate System ◽  
Local Coordinate System ◽  
Three Dimensional ◽  
Identification Accuracy ◽  
Measuring System ◽  
Laser Triangulation ◽  
Gauge Block ◽  
Numerical Simulation Methods ◽  
Least Squares Minimization ◽  
Evolution Approach

AbstractThe paper discusses the derivation of an accurate coordinate measuring system consisting of two, three, or four sensors based on the records of four fixed laser triangulation sensors done for a gauge block in movement. Three-dimensional case is considered. In the simulations, using a set of distances quadruplets, parameters of sensors in a local sensors coordinate system are determined through a least squares minimization process using the Differential Evolution approach. The influence of the measurement and rounding inaccuracy on the identification accuracy using numerical simulation methods are assessed.

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