• Journal of Sensor Science and Technology
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• v.28 no.1
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• pp.30-35
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• 2019

Inertial measurement units (IMUs) are widely used for wearable motion-capturing systems in the fields of biomechanics and robotics. When the IMUs are combined with optical motion sensors (hereafter, OPTs) for their complementary capabilities, it is necessary to align the coordinate system orientations between the IMU and OPT. In this study, we compare the application of two coordinate transformation-based orientation alignment methods between two coordinate systems. The first method (M1) applies angular velocity coordinate transformation, while the other method (M2) applies gyroscopic angle coordinate transformation. In M1 and M2, the angular velocities and angles, respectively, are acquired during random movement for a least-square algorithm to determine the alignment matrix between the two coordinate systems. The performance of each method is evaluated under various conditions according to the type of motion during measurement, number of data points, amount of noise, and the alignment matrix. The results show that M1 is free from drift errors, while drift errors are present in most cases where M2 is applied. Thus, this study indicates that M1 has a far superior performance than M2 for the alignment of IMU and OPT coordinate systems for motion analysis.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.309-315
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• 2003

This study is aimed to research the precise and efficient method for coordinate transformation. In Korea, it is necessary to convert existing digital maps in TM coordinates to that in KTRF from 2007. In this study, coordinate transformation methods and conversion area are tested and analyzed. In the results of experiment, it shows that Affine method is preciser than Helmert method. But Affine method is have more distortion than Helmert method.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.26 no.1
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• pp.1-14
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• 1998

Various numerical methods for the two dimensional shallow water equations have been applied to the problems of flood routing, tidal circulation, storm surges, and atmospheric circulation. These methods are often based on the Alternating Direction Implicity(ADI) method. However, the ADI method results in inaccuracies for large time steps when dealing with a complex geometry or bathymetry. Since this method reduces the performance considerably, a fully implicit method developed by Wilders et al. (1998) is used to improve the accuracy for a large time step. Finite Difference Methods are defined on a rectangular grid. Two drawbacks of this type of grid are that grid refinement is not possibile locally and that the physical boundary is sometimes poorly represented by the numerical model boundary. Because of the second deficiency several purely numerical boundary effects can be involved. A boundary fitted curvilinear coordinate transformation is used to reduce these difficulties. It the curvilinear coordinate transformation is used to reduce these difficulties. If the coordinate transformation is orthogonal then the transformed shallow water equations are similar to the original equations. Therefore, an orthogonal coorinate transformation is used for defining coordinate system. A multigrid (MG) method is widely used to accelerate the convergence in the numerical methods. In this study, a technique using a MG method is proposed to reduce the computing time and to improve the accuracy for the orthogonal to reduce the computing time and to improve the accuracy for the orthogonal grid generation and the solutions of the shallow water equations.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.11a
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• pp.9-16
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• 2004

Performing adjustments where the observation equations involve more than a single measurement are General Least Squares(GLS) and Total Least Squares(TLS). This paper introduces theory of the GLS and TLS and compared experimentally accuracy and efficiency of those through 2D conformal coordinate transformation and 2D affine coordinate transformation. In conclusion, in case of 2D coordinate transformation, GLS can produce a little more accurate and efficient than TLS. In survey fields, The GLS and TLS can be used cooperatively for adjusting the actual coordinate measurements.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.11
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• pp.99-109
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• 2004

This paper proposes precision evaluation method for the positioning error of three-DOF translational parallel mechanism. The proposed method uses conventional CMM as metrology equipment to measure the position of end-effector. In order to obtain accurate measurement data from CMM, the transform relationship between the coordinate system of the parallel mechanism and the CMM coordinate system must be identified. For this purpose, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate error components at any arbitrary position of the end-effector is derived. In addition, mathematical fitting models to represent the position error components in the two-dimensional workspace of the parallel mechanism are also constructed based on response surface methodology. The proposed error evaluation method proves its effectiveness through the experimental results and its application to real three-DOF parallel mechanism.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.3
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• pp.44-52
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• 2004

This paper proposed a error compensation methodology for three-DOF translational parallel manipulator. The proposed method uses CMM (coordinate measuring machine) as metrology equipment to measure the position of end-effector. To identify the transform relationships between the coordinate system of the parallel manipulator and the CMM coordinate system, a new coordinate referencing (or coordinate system identification) technique is presented. By using this technique, accurate coordinate transformation relationships are efficiently established. According to these coordinate transformation relationships, an equation to calculate the compensating error components at any arbitrary position of the end-effector is derived. In this paper, Monte Carlo simulation method is applied to simulate the compensation process. Through the simulation results, the proposed error compensation method proves its effectiveness and feasibility.

• Journal of the Korean Society for Precision Engineering
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• v.6 no.4
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• pp.119-125
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• 1989

This paper presents a method of analog signal processing for a coordinate transformation. Through the proposed method, two-dimensional position information obtanided from any type of null-detector can be transformed into the information with repect to world coordinate system. In order to implement the method, a null- detection device which consists of four optical proximity sensor is developed. Through the experiments for performance evaluation, the effectiveness of the proposed method has been demonstrated.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.224-229
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• 2012

In this paper, we propose a correction method for astronomical telescope using recursive least square method. There are two ways to move a telescope : equatorial operation and altazimuth operation. We must align polar axis of a equatorial telescope with the north celestial pole and adjust the horizontal axis of a altazimuth telescope exactly to match the celestial coordinate system with the telescope coordinate system. This process needs time and expertise. We can skip existing process and correct a tracking error easily by deriving the relationship of the celestial coordinate system and the telescope coordinate system using the proposed correction method. We obtain the coordinate of a celestial body in the celestial coordinate system and the telescope coordinate system and derive a transformation matrix through the obtained coordinate. We use recursive least square method to estimate the unknown parameters of a transformation matrix. Finally, we implement a telescope control system using a microprocessor and verify the performance of the correction method. Through an experiment, we show the validity of the proposed correction method.

• 제어로봇시스템학회:학술대회논문집
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• 1987.10b
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• pp.109-114
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• 1987

In this thesis, we work on the curve recognition with real time processing and the Robot tracking method on recognized curve. Image information of segment curve is supplied to computer to run to a Robot so that it is a feedback system. Image coordinate frame to world coordinate transformation represents in this paper and curve matching algorithm subscribes by two method, first transformation matching algorithm, second image coordinate matching algorithm. Also Robot running time to computer image processing time relationships finally includes.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.279-289
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• 2021

GNSS receivers capable of tracking multiple Global Navigation Systems (GNSSs) simultaneously are widely used. In order to estimate accurate user position and velocity, it is necessary to consider the key elements that contribute to the interoperability of the different GNSSs. Typical examples are the time system and the coordinate system. Each GNSS is operated based on its own reference time system depending on when the system was developed and whether the leap seconds are applied. In addition, each GNSS is designed based on its own coordinate system based on earth model constant values. This paper addresses the interoperability issues from the viewpoint of Single Point Positioning (SPP) users utilizing multiple GNSS signals from GPS, GLONASS, BeiDou, and Galileo. Since the broadcast ephemerides of each GNSS are based on their own time and coordinate systems, the time and the coordinate systems should be unified for any user algorithm. For this purpose, this paper proposes a method of converting each GNSS coordinate system into the reference coordinate system through Helmert transformation. The error of the broadcast ephemerides was calculated with the precise ephemerides provided by the International GNSS Service (IGS). The effectiveness of the proposed multi-GNSS correction and transformation method is verified using the Multi-GNSS Experiment (MGEX) station data.