• 제어로봇시스템학회:학술대회논문집
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• 1994.10a
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• pp.289-292
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• 1994

In this paper, the equations of motion are constructed systematically for multibody systems containing closed kinematic loops. For the displacement analysis of the closed loops, we introduce a new mixed coordinates by adding to the reference coordinates, relative coordinates corresponding to the degrees of freedom of the system. The mixed coordinates makes easy derive the explicit closed form solution. The explicit functional relationship expressed in closed form is of great advantages in system dimension reduction and no need of an iterative scheme for the displacement analysis. This forms of equation are built up in the general purpose computer program for the kinematic and dynamic analysis of multiboty systems.

• Journal of Mechanical Science and Technology
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• v.17 no.8
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• pp.1133-1139
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• 2003

In this paper, a numerical algorithm for the kinematic analysis of a multi-link five-point suspension system is presented. The kinematic analysis is carried out in terms of the rectangular Cartesian coordinates of some defined points in the links and at the joints. Geometric constraints are introduced to fix the relative positions between the points belonging to the same rigid body. Position, velocity and acceleration analyses are carried out. The presented formulation in terms or this system of coordinates is simple and involves only elementary mathematics. The results of the kinematic analysis are presented and discussed.

• Spatial Information Research
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• v.13 no.2 s.33
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• pp.129-138
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• 2005

In this paper, a 3D position tracking algorithm for a moving objects using a stereo CCD cameras was proposed. This paper purposed the method to extract the coordinates of the moving objects. That is improve the operating and data processing efficiency. We were applied the relative orientation far the stereo CCD cameras and image coordinates extraction in the left and right images after the moving object segmentation. Also, it is decided on 3D position far moving objects using an acquired image coordinates in the left and right images. We were used independent relative orientation to decide the relative location and attitude of the stereo CCD cameras and RGB pixel values to segment the moving objects. To calculate the coordinates of the moving objects by space intersection. And, We conducted the experiment the system and compared the accuracy of the results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.11
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• pp.3398-3407
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• 1996

In this paper, we derive an algorithm and develope a computer program which analyze rapidly and precisely the inverse kinematics of robotic mechanism with spatial complex chain structure based on the relative coordinates. We represent the inverse kinematic problem as an optimization problem with the kinematic constraint equations. The inverse kinematic analysis algorithm, therefore, consists of two algorithms, the main, an optimization algorithm finding the motion of independent joints from that of an end-effector and the sub, a forward kinematic analysis algorithm computing the motion of dependent joints. We accomplish simulations for the investigation upon the accuracy and efficiency of the algorithm.

• Journal of Astronomy and Space Sciences
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• v.15 no.1
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• pp.183-196
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• 1998

The Synthetic Aperture Radar(SAR) image and the Digital Elevation Model(DEM) of an target area are put into use to generate three dimensional image map. An method of image map generation is explained. The orbit and attitude determination of satellite makes it possible to model signal acquisition configuration precisely, which is a key to mapping image coordinates to geographic coordinates of concerned area. An application is made to RADARSAT in the purpose of testing its validity. To determine the orbit, zero Doppler range is used. And to determine the attitude, Doppler centroid frequency, which is the frequency observed when target is put in the center of antenna's view, is used. Conventional geocoding has been performed on the basis of direct method(mapping image coordinates to geographic coordinates), but in this reserch the inverse method(mapping from geographic coordinates to image coordinates) is taken. This paper shows that precise signal acquisition modeling based on the orbit and attitude determination of satellite as a platform leads to a satellite-centered accurate geocoding process. It also shows how to model relative motion between space-borne radar and target. And the relative motion is described in ECIC(earth-centered-initial coordinates) using Doppler equation and signal acquisition geometry.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.28 no.6
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• pp.637-643
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• 2010

In this study, we developed a Portable Multi-sensor System, which consists of a video camera, a GPS/MEMS IMU and a UMPC to acquire video images and position/attitude data. We performed image georeferencing based on the bundle adjustment without ground control points using the acquired data and then evaluated the effectiveness of our system through the accuracy verification. The experimental results showed that the RMSE of relative coordinates on the ground point coordinates obtained from our system was several centimeters. Our system can be efficiently utilized to obtain the 3D model of object and their relative coordinates. In future, we plan to improve the accuracy of absolute coordinates through the rigorous calibration of the system and camera.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.2
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• pp.576-590
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• 2023

Machine learning is widely used in various academic fields, and recently it has been actively applied in the medical research. In the medical field, machine learning is used in a variety of ways, such as speeding up diagnosis, discovering new biomarkers, or discovering latent traits of a disease. In the respiratory field, a relative regional air volume change (RRAVC) map based on quantitative inspiratory and expiratory computed tomography (CT) imaging can be used as a useful functional imaging biomarker for characterizing regional ventilation. In this study, we seek to predict RRAVC using various regular machine learning models such as extreme gradient boosting (XGBoost), light gradient boosting machine (LightGBM), and multi-layer perceptron (MLP). We experimentally show that MLP performs best, followed by XGBoost. We also propose several relative coordinate systems to minimize intersubjective variability. We confirm a significant experimental performance improvement when we apply a subject's relative proportion coordinates over conventional absolute coordinates.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.2
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• pp.71-78
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• 2003

This research proposes an implementation method of linearized equations of motion for multibody systems with closed loops. The null space of the constraint Jacobian is first pre-multiplied to the equations of motion to eliminate the Lagrange multiplier and the equations of motion are reduced down to a minimum set of ordinary differential equations. The resulting differential equations are functions of all relative coordinates, velocities, and accelerations. Since the variables are tightly coupled by the position, velocity, and acceleration level coordinates, direct substitution of the relationships among these variables yields very complicated equations to be implemented. As a consequence, the reduced equations of motion are perturbed with respect to the variations of all variables, which are coupled by the constraints. The position velocity and acceleration level constraints are also perturbed to obtain the relationships between the variations of all relative coordinates, velocities, and accelerations and variations of the independent ones. The Perturbed constraint equations are then simultaneously solved for variations of all variables only in terms of the variations of the independent variables. Finally, the relationships between the variations of all variables and these of the independent ones are substituted into the variational equations of motion to obtain the linearized equations of motion only in terms of the independent variables variations.

• Journal of Astronomy and Space Sciences
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• v.35 no.4
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• pp.287-293
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• 2018

This paper presents a satellite relative navigation strategy for formation flying, which chooses an appropriate navigation algorithm according to the operating environment. Not only global positioning system (GPS) measurements, but laser measurements can also be utilized to determine the relative positions of satellites. Laser data is used solely or together with GPS measurements. Numerical simulations were conducted to compare the relative navigation algorithm using only laser data and laser data combined with GPS data. If an accurate direction of laser pointing is estimated, the relative position of satellites can be determined using only laser measurements. If not, the combined algorithm has better performance, and is irrelevant to the precision of the relative angle data between two satellites in spherical coordinates. Within 10 km relative distance between satellites, relative navigation using double difference GPS data makes more precise relative position estimation results. If the simulation results are applied to the relative navigation strategy, the proper algorithm can be chosen, and the relative position of satellites can be estimated precisely in changing mission environments.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.465-470
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• 2001

This paper presents an algorithm which seeks steady-state equilibrium positions of constrained multibody systems driven by constant generalized speeds. Since the relative coordinates are employed, the constraint equations at cut joints are incorporated into the formulation. The proposed algorithm leads to nonlinear equations that need to be solved iteratively. This algorithm should satisfy both types of conditions: the force equilibrium equations and the kinematic constraint equations. To verify the effectiveness of the proposed algorithm, two numerical examples are solved and the results are compared with those of a commercial program. This method, compared to the conventional method of using dynamic analysis, has the advantage of computational efficiency and stability.