• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2379-2384
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• 2005

We propose a novel method for object recognition using the smart tag system with a stereo vision on a pan-tilt mechanism. We developed a smart tag which included IRED device. The smart tag is attached onto the object. We also developed a stereo vision system which pans and tilts for the object image to be the centered on each whole image view. A Stereo vision system on the pan-tilt mechanism can map the position of IRED to the robot coordinate system by using pan-tilt angles. And then, to map the size and pose of the object for the robot to coordinate the system, we used a simple model-based vision algorithm. To increase the possibility of tag-based object recognition, we implemented our approach by using as easy and simple techniques as possible.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.215-219
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• 1996

We developed a part of hydraulic stroke sensing cylinder for te purpose of position controlbyusing magnetic sensor and evaluated variously its performance its performance. In this paper, for the evaluation of the developed cylinder under various temperature change, thermal control systems are designed and controlled. It is composed of an heater case, temperature sensor, and interface circuits which included SCR(silicon controlled rectifier) for the control of the voltage's phase. To obtain various temperature conditions, the thermal systems are controlled by using Ziegler-Nichols PED tuning method. The thermalcontrol systems are used to experiment to evaluate whether the developed cylinder can obtain a stable output signal for detecting a stroke of the cylinder under the controlled temperature condition.

• Journal of Biosystems Engineering
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• v.23 no.2
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• pp.179-186
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• 1998

This study was conducted to sense posture of an autonomous tractor using a DGPS, a gyro compass, and a potentiometer. Posture sensing system was constructed and its accuracy was evaluated. The accuracy of DGPS was evaluated under stationary and moving conditions, and the performance of the gyro compass and the potentiometer was investigated by measuring bearing and steering angles, respectively. Also, the effect of DGPS interference by obstacles was evaluated experimentally. The position accuracy was about 6.6cm(95%) under the stationary condition and 10 cm at sharp turning condition. Steering angle of the tractor could be related linearly to the output of the potentiometer that was installed on the rotating center of a knuckle arm. The positioning accuracy of the DGPS varied significantly according to the number of visible GPS satellites, but was good with more than 7 satellites. The DGPS gave bad solutions for sensing the posture of tractor when signals from satellites or the correction data from the base were interfered by obstacles.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.885-887
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• 2003

The purpose of this investigation is to generate true orthophotos from high resolution satellite images. The major works of this research include 4 parts: (1) determination of orientation parameters, (2) generating traditional orthophotos using terrain model, (3) relief correction for buildings, and (4) process for hidden areas. To determine the position of satellites, we correct the onboard orientation parameters to fine tune the orbit. In the generation of traditional orthophotos, we employ orientation parameters and digital terrain model(DTM) to rectify tilt displacements and relief displacements for terrain. We, then, compute relief displacements for buildings with digital building model (DBM). To avoid double mapping, we detect hidden areas. Due to the satellite’s small field of view, an efficient method for the detection of hidden areas and building rectification will be proposed in this paper. Test areas cover the city of Kaohsiung in southern Taiwan. Test images are from the QuickBird satellite.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.212-216
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• 1998

For a Switched Reluctance Motor(SRM) drive, the important things are 1) reducing torque ripple, 2) improving efficiency, 3) sensorless speed control, 4) accurate position. The position information impotant for the efficiency and smoothness drives. Since SRMs characteristics are nonlinear. It is difficult to estimated phase current in saturation region. This paper describes a method for indirect sensing of the rotor position in SRM which use both voltage and current. The method obtains rotor position by using unconducting phase. The information about the rotor position is achieved by differentiating the unconducting phase current or the voltage gradient. And then, this paper presents a torque control with indirect rotor position detection methods. This torque control is achieved by developing a detailed nonlinear model of the motor.

• International Journal of Control, Automation, and Systems
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• v.2 no.4
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• pp.485-493
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• 2004

Open-loop position estimation methods are commonly used in mobile robot applications. Their strength lies in the speed and simplicity with which an estimated position is determined. However, these methods can lead to inaccurate or unreliable estimates. Two position estimation methods are developed in this paper, one using a single optical flow sensor and a second using two optical sensors. The first method can accurately estimate position under ideal conditions and also when wheel slip perpendicular to the axis of the wheel occurs. The second method can accurately estimate position even when wheel slip parallel to the axis of the wheel occurs. Location of the sensors is investigated in order to minimize errors caused by inaccurate sensor readings. Finally, a method is implemented and tested using a potential field based navigation scheme. Estimates of position were found to be as accurate as dead-reckoning in ideal conditions and much more accurate in cases where wheel slip occurs.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.1
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• pp.10-18
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• 2007

In this paper, we address the node positioning method for minimizing the overlap sensing areas in wireless sensor networks with adjustable sensing ranges. To find a optimal node position, we derive a optimal equations by using the overlapped areas, each node's radiuses and expended angles of opposite neighboring nodes. Based on it, we devise a new node positioning method, called as ASRC(Adjustable Sensing Ranges Control). Unlike existing condition based model, our proposed method is derived from mathematical formula, and we confirm its validity through various simulations.

• Journal of Astronomy and Space Sciences
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• v.16 no.1
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• pp.69-78
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• 1999

We have developed an attitude sensing S/W system, one of modules of Mission Analysis System(MAS), which simulates attitude sensing data as almost the same as the real sensor of a satellite in orbit. When attitude elements($alpha,delta$) of a satellite and positions of Earth, Moon, and Sun are given, the S/W system calculates look angles and dihedral angles of each celestial bodies relative to the rotations axis of the satellite. It consists of two sub-modules : One is ephemeris service module which consider the perturbations of four planets(Venus, Mars, Jupiter, Saturn) for positions of Sun and Moon and 4 $\times$4 earth gravitational potential terms for a satellite's position. The other is attitude simulation module which generates attitude sensing data. Varying the rotational axis of a satellite and it's orbital elements, we simulated the generating attitude sensing data with this S/W system and discussed their results.

• Journal of the Korean Society of Safety
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• v.5 no.2
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• pp.6-16
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• 1990

In this paper, the natural convection in a square enclosure, partly heated from below, with two adiabatic vertical wall and one upper horigental wall is studied nomerically. In numerical study, SIMPLE(Semi-Implicit for Pressure Linked Equation) algorithems are applied for the integration of momentum and energy equation. The grid size used in this study is the coordinates of size (22$\times$22). As a result of numerical analysis, the initial fluid flow depends on the thermal diffusion, but, as time passes, the fluid flow depends on convection and buoyancy of the enclosure. In Case 1, the heating region was been in the central position of the bottom wall. In case 2, the heating region was in the left position of the bottom. In case of Case 1, the lapse time of sensing the temperature of 72$^{\circ}C$ is approximately 15 sec almost at the same time in the coordinates (6, 22), (11, 22). In case of Case 2, the lapse time in the coordinates (6, 22), (11, 22) was 27 sec, 25 sec repectively. Also in case of Case 1 or Case 2, the gradients of y-position of the two sensors are transposed each other.

• Korean Journal of Remote Sensing
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• v.26 no.3
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• pp.335-346
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• 2010

Recently, ESA (European Space Agency) has launched CryoSAT-2 for polar ice observations. CryoSAT-2 is equipped with a SIRAL (SAR/interferometric radar altimeter), which is a high spatial resolution radar altimeter. Conventional altimeters cannot measure a precise three-dimensional ground position because of the large footprint diameter, while SIRAL altimeter system accomplishes a precise three-dimensional ground positioning by means of interferometric synthetic aperture radar technique. In this study, we developed an efficient SIRAL SARIn mode processing technique to measure a precise three-dimensional ground position. We first simulated SIRAL SARIn RAW data for the ideal target by assuming the flat Earth and linear flight track, and second accessed the precision of three-dimensional geopositioning achieved by the proposed algorithm. The proposed algorithm consists of 1) azimuth processing that determines the squint angle from Doppler centroid, and 2) range processing that estimates the look angle from interferometric phase. In the ideal case, the precisions of look and squint angles achieved by the proposed algorithm were about -2.0 ${\mu}deg$ and 98.0 ${\mu}deg$, respectively, and the three-dimensional geopositioning accuracy was about 1.23 m, -0.02 m, and -0.30 m in X, Y and Z directions, respectively. This means that the SIRAL SARIn mode processing technique enables to measure the three-dimensional ground position with the precision of several meters.