• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.711-719
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• 2010

Heliostat, as a concentrator reflecting the incident solar energy to the receiver located at the tower, is the most important system in the tower-type solar thermal power plant, since it determines the efficiency and performance of solar thermal plower plant. Thus, a good sun tracking ability as well as its good optical property are required. In this paper, we propose a method to compensate the heliostat sun tracking error. We first model the sun tracking error, which could be measured using BCS (Beam Characterization System), by multilayered neural network. Then the extended Kalman filter was employed to train the neural network. Finally the model is used to compensate the sun tracking errors. Simulated result shows that the method proposed in this paper improve the heliostat sun tracking performance dramatically. It also shows that the training of neural network by the extended Kalman filter provides faster convergence property, more accurate estimation and higher measurement noise rejection ability compared with the other training methods like gradient descent method.

• Journal of the Semiconductor & Display Technology
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• v.14 no.3
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• pp.73-77
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• 2015

This paper proposes an object tracking system according to reliability assessment of learning in mobile environments. The proposed system is based on markerless tracking, and there are four modules which are recognition, tracking, detecting and learning module. Recognition module detects and identifies an object to be matched on current frame correspond to the database using LSH through SURF, and then this module generates a standard object information that has the best reliability of learning. The standard object information is used for evaluating and learning the object that is successful tracking in tracking module. Detecting module finds out the object based on having the best possible knowledge available among the learned objects information, when the system fails to track. The experimental results show that the proposed system is able to recognize and track the reliable objects with reliability assessment of learning for the use of mobile platform.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.2B
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• pp.171-177
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• 2002

As speed and capacity of optical communication system increase dramatically, polarization-mode-dispersion compensation(PMDC) becomes a hot issue in these days. In this paper, we introduce a new state-of-polarization (SOP) tracking algorithm that can be used in a PMDC system. The new SOP tracking algorithm is also based on optical heterodyne coherent detection technique like the previous algorithm that we have reported before. However, unlike the previous algorithm, the new algorithm requires only three times of measurement in any circumstances to find the exact SOP information so that it can effectively be applied to PMDC system where very fast and stable operation is indispensible.

• Journal of Institute of Control, Robotics and Systems
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• v.21 no.1
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• pp.7-13
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• 2015

Unmanned air vehicles (UAVs) are getting popular not only as a private usage for the aerial photograph but military usage for the surveillance, reconnaissance and supply missions. For an UAV to successfully achieve these kind of missions, geolocation (localization) must be implied to track an interested target or fly by reference. In this research, we adopted multi-sensor fusion (MSF) algorithm to increase the accuracy of the geolocation and verified the algorithm using two multicopter UAVs. One UAV is equipped with an optical camera, and another UAV is equipped with an optical camera and a laser range finder. Throughout the experiment, we have obtained measurements about a fixed ground target and estimated the target position by a series of coordinate transformations and sequential Kalman filter. The result showed that the MSF has better performance in estimating target location than the case of using single sensor. Moreover, the experimental result implied that multi-sensor geolocation algorithm is able to have further improvements in localization accuracy and feasibility of other complicated applications such as moving target tracking and multiple target tracking.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.11
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• pp.2733-2737
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• 2014

Motion detection according to the movement and the change area detection method according to the background difference and the motion history image for use in a motion estimation technique using a real-time image, the motion detection method according to the optical flow, the back-projection of the histogram of the object to track for motion tracking At the heart of MeanShift center point of the object and the object to track, while used, the size, and the like due to the motion tracking algorithm CamShift, Kalman filter to track with direction. In this paper, we implemented the motion detection algorithm based on color and shape information of the object and verify.

• The KIPS Transactions:PartB
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• v.12B no.3 s.99
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• pp.301-312
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• 2005

Three different cases should be considered for motion tracking: moving object with fixed camera, fixed object with moving camera and moving object with moving camera. Two methods are widely used for motion tracking: the optical flow method and the difference frame method. The optical new method is mainly used when either one, object or camera is fixed. This method tracks object using time-space vector which compares object position frame by frame. This method requires heavy computation, and is not suitable for real-time monitoring system such as DVR(Digital Video Recorder). The different frame method is used for moving object with fixed camera. This method tracks object by comparing the difference between background images. This method is good for real-time applications because computation is small. However, it is not applicable if the camera is moving. This thesis proposes and implements the motion tracking system using the difference frame method with PTZ(Pan-Tilt-Zoom) control. This system can be used for moving object with moving camera. Since the difference frame method is used, the system is suitable for real-time applications such as DVR.

• Transactions of the Society of Information Storage Systems
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• v.1 no.1
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• pp.67-72
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• 2005

This study proposes a design methodology to determine the optimum configurations of the optical flying head (OFH) for near-field recording systems. Since the OFH requires stricter static and dynamic characteristics of slider air-bearings within an optical tilt tolerance over the entire recording band, an optimum design to keep the focusing and tracking ability stable is essential. The desired flying characteristics considered in this study are to minimize the variation in flying height between the SIL and the disk from a target value, satisfying the restriction of the minimum flying height, to keep the pitch and roll angles within an optical tilt tolerance, and to ensure a higher air-bearing stiffness. Simulation results demonstrate the effectiveness of the proposed design methodology by showing that the static and dynamic flying characteristics of the optimally designed OFH are enhanced in comparison with those of the initial. The gap between the SIL and the disk can be kept at less than 100 nm even if the optical tilt tolerance of the SIL is considered.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.62-76
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• 2002

This paper describes the design of a Coordinates Tracking algorithm for EOTS and its error analysis. EOTS stabilizes the image sensors such as FLIR, CCD TV camera, LRF/LD, and so on, tracks targets automatically, and provides navigation capability for vehicles. The Coordinates Tracking algorithm calculates the azimuth and the elevation angle of EOTS using the inertial navigation system and the attitude sensors of the vehicle, so that LOS designates the target coordinates which is generated by a Radar or an operator. In the error analysis in this paper, the unexpected behaviors of EOTS that is due to the time delay and deadbeat of the digital signals of the vehicle equipments are anticipated and the countermeasures are suggested. This algorithm is verified and the error analysis is confirmed through simulations. The application of this algorithm to EOTS will improve the operational capability by reducing the time which is required to find the target and support especially the flight in a night time flight and the poor weather condition.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.547-552
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• 1989

Single mode optical fiber interferometeric sensors using phase tracking homodyne detection are typically susceptible to environmentally induced temperature fluctuations and other types of disturbances. In this paper compensator is described, which is a simple and effective phase tracking feedback electronic circuit must be output signal stabilized to achieve maximln sensitivity and linearity of Mach-Zehnder fiber-optic interferomter in the presence of differential phase drift. The phase tracking range of the piezoelectric cylinder in the reference arm is .+-.3.7.pi.rad, and the probe mass about 1 gram in the sensing ann was used for measurements of the gravity acceleration.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.568-574
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• 2004

On-line phase tracking of an extrinsic Fabry-Perot interferometer (EFPI) and experimental vibration control of a composite beam with a sensing-patch are investigated. We propose a sensing-patch for the compensation of the interferometric non-linearity. In this paper, a sensing-patch that comprises an EFPI and a piezo ceramic(PZT) is fabricated and the characteristics of the sensing-patch are experimentally investigated. A simple and practical logic is applied for the real-time tracking of optical phase of an interferometer. Experimental results show that the proposed sensing-patch does not have the non-linear behavior of conventional EFPI and hysteresis of piezoelectric material. Moreover, it has good strain resolution and wide dynamic sensing range. Finally, the vibration control with the developed sensing-patch has been performed using Fuzzy logic controller, and the possibility of sensing-patch as a sensoriactuator is considered.