• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.7
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• pp.680-687
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• 2008

This paper presents map creation algorithm and initial attitude estimation method for the proposed optical head tracker system. The optical head tracker system consists of the IR stereo cameras and infrared LEDs as features on the helmet. In order for the stereo camera to track the luminous LEDs, it must take in to account the light radiation from the LEDs to determine the position of the center points. The proposed map creation algorithm makes map data about the position of features center points on the helmet frame. Also, initial attitude estimation method is proposed to estimate the initial attitude and position of a pilot head from the camera frame by the use of the feature pattern on the helmet. Therefore, the head motion can be expressed with respect to the body frame of a flight.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.3
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• pp.260-265
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• 2003

The energy of PV system is different as the elevation and aximuth of the sun. This paper deals with the economical position tracking system development for the stand alone PV system. We have made more economical solar position tracking system which is used a tracking program than other similar systems. It is applied to the solar lighting lamp. We have made a comparative study of the energy amount between the fixed type and the tracking type during some period. The improved efficiency of the system is about 86 %.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1034-1036
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• 2006

In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and, composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.3
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• pp.243-249
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• 2021

The star tracker detects microscopic star light in space and compares it with a stored list of stars to calculate the satellite's position in the inertial coordinate system. If other light, such as the sun or the earth, enters the optical head, the star cannot be recognized and the star tracker cannot be operated. In particular, strong light such as the sun affects not only operation but also the performance of the star tracker. The sun exclusion angle of the star tracker is one of the important factors determining the performance of the star tracker. This paper performs the verification of the star tracker's sun exclusion angle. In order to verify the sun exclusion angle, we predict the sun exclusion time of the star tracker and compare it to the actual sun exclusion time of the GEO-KOMPSAT-2A star tracker. In addition, the performance of the star tracker is analyzed for normal operations against the sun exclusion in the optical head. It shows that the actual sun exclusion is maintained under the range of 26 degrees, the performance requirement of the star tracker, and the star tracker operates normally in spite of the sun exclusion.

• Journal of the Korea Computer Graphics Society
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• v.3 no.2
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• pp.35-43
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• 1997

In monitor-based AR(Augmented Reality) systems, it is required to know the position and direction of a camera in order to combine real images from a camera with virtual images exactly_ Because a tracker is parted from a camera, however, there is a registration error caused by the inconsistency of a tracker with a camera. In this paper, we describe the error correction method using genetic algorithm. This method looks for the position and direction of a camera using genetic algorithm and solves the error correction matrix of it. And then it is registered of the real images and the revised virtual image. It has an effect on the error correction caused by the misalignment of a tracker with a camera in complex AR systems.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.7
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• pp.693-701
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• 2010

In this paper, it is proposed that an attitude and position estimation algorithm based on a stereo camera system for a helmet tracker. Stereo camera system consists of two CCD camera, a helmet, infrared LEDs and a frame grabber. Fifteen infrared LEDs are feature points which are used to determine the attitude and position of the helmet. These features are arranged in triangle pattern with different distance on the helmet. Vision-based the attitude and position algorithm consists of feature segmentation, projective reconstruction, model indexing and attitude estimation. In this paper, the attitude estimation algorithm using UQ (Unit Quaternion) is proposed. The UQ guarantee that the rotation matrix is a unitary matrix. The performance of presented algorithm is verified by simulation and experiment.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.559-562
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• 2002

In the photovoltaic power system, it is required that we obtain as much as generated power as possible. This paper describes improved stand-alone photovoltaic system efficiency(SPVS) using the sun position tracker for the solar lighting lamp through the comparison test of the power efficiency between the tacking type and the non-tacking type one.

• International Journal of Aeronautical and Space Sciences
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• v.11 no.1
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• pp.31-40
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• 2010

For weapon cueing and Head-Mounted Display (HMD), it is essential to continuously estimate the motion of the helmet. The problem of estimating and predicting the position and orientation of the helmet is approached by fusing measurements from inertial sensors and stereo vision system. The sensor fusion approach in this paper is based on nonlinear filtering, especially expended Kalman filter(EKF). To reduce the computation time and improve the performance in vision processing, we separate the structure estimation and motion estimation. The structure estimation tracks the features which are the part of helmet model structure in the scene and the motion estimation filter estimates the position and orientation of the helmet. This algorithm is tested with using synthetic and real data. And the results show that the result of sensor fusion is successful.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.7
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• pp.1000-1003
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• 2021

In this paper, we investigate how to track illegal drones by using communication signal received from illegal drones, which is a promising candidate position tracking scheme for anti-drone systems, and is particularly effective in tracking small illegal drones in urban areas. We propose an enhanced tracking scheme using multiple antennas to improve the performance of tracking by reducing the error of position tracking. In the proposed tracking scheme, a tracker is equipped with four receive antennas that are evenly spaced 90 degrees apart, and received signal strength indicators (RSSIs) received by four receive antennas are pre-averaged before being used to calculate the distance between tracker and target. Our numerical results show that the proposed scheme outperforms the conventional scheme in terms of accuracy.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.82-86
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• 2004

A fuzzy rule-based hand-motion estimation algorithm is proposed for a 6 dimensional spatial tracker in which low cost accelerometers and gyros are employed. To be specific, beginning and stopping of hand motions needs to be accurately detected to initiate and terminate integration process to get position and pose of the hand from accelerometer and gyro signals, since errors due to noise and/or hand-shaking motions accumulated by integration processes. Fuzzy rules of yes or no of hand-motion-detection are here proposed for rules of accelerometer signals, and sum of derivatives of accelerometer and gyro signals. Several experimental results and shown to validate our proposed algorithms.