• Journal of Astronomy and Space Sciences
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• 제29권4호
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• pp.351-362
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• 2012

We made a study on real-time determination method for relative position using the laser-measured distance data between satellites. We numerically performed the determination of relative position in accordance with extended Kalman filter algorithm using the vectors obtained through nonlinear equation of relative motion, laser simulator for distance measurement, and attitude determination of chief satellite. Because the spherical parameters of relative distance and direction are used, there occur some changes in precision depending on changes in relative distance when determining the relative position. As a result of simulation, it was possible to determine the relative position with several millimeter-level errors at a distance of 10 km, and sub-millimeter level errors at a distance of 1 km. In addition, we performed the determination of relative position assuming the case that global positioning system data was not received for long hours to see the impact of determination of chief satellite orbit on the determination of relative position. The determination of precise relative position at a long distance carried out in this study can be used for scientific mission using the satellite formation flying.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1609-1614
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• 2003

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. To implement the concept in collision avoidance of multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.1231-1233
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• 1996

This paper presents an estimation of relative distance and angle from a mobile robot to an object. From the number of pulses required to make the mobile robot move to the feature point, we find the relative distance and angle between the mobile robot and the object. The proposed method shows a practical way of measuring the relative distance and angle between the mobile robot and an object without setting up real world coordinate system.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.132-144
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• 2004

This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning method for multiple robots to do a collaborative job.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.37.2-37
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• 2002

1. Introduction 2. Problem Formulation 3. Avoidability Measure And Relative Distance 4. Artificial Potential Field in Terms of Relative Distance 5. Simulation Results 6. Conclusions 7. Reference

• 한국자동차공학회논문집
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• 제6권5호
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• pp.222-227
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• 1998

Collision warning systems have been an active research and development area as the interests and demands for ASV's (Advanced Safety Vehicles) have increased. This paper presents an experimental investigation of a collision warning system for automobiles. A collision warning HiLS(Hardware-in-the-Loop Simulation) system has been designed and used to test the collision warning algorithm, radar sensors, and warning displays under realistic operating conditions in the laboratory. the collision warning algorithm is operated by a warning index, which is a function of the warning distance and the braking distance. The computer calculates velocities of the preceding vehicle and following vehicle, relative distance and relative velocity of the vehicles using vehicle simulation models. The relative distance and the relative velocity are applied to the vehicle simulator controlled by a DC motor.

• 수산해양기술연구
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• 제33권1호
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• pp.1-8
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• 1997

To find the tooth selectivity of the dredge for catching the ark shell Scapharca broughtonii, the probabilities of the ark shells which are not sifting through the gaps between teeth were calculated for the various shell lengths. Considering that these probabilities are in proportion to the relative catching efficiencies, selectivity curves for the ark shell dredge were estimated for the various gaps between teeth. The ratio of the shell length of ark shell to the distance between teeth indicating the relative catching efficiencies of 0%, 50%, 100% respectively, were calculated by using these selectivity curves, and the values were 1.00, 1.32, 1.54 in the distance of 4.0cm between teeth and then, the ratios showed a slight tendency to decrease as the distance between teeth increased in the relative catching efficiency of 100%, In addition, the range of shell length for catching, that is, the range of selective shell length by the distance between teeth was 0.54 in the distance of 4.0cm between teeth.

• 한국전자통신학회논문지
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• 제11권12호
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• pp.1175-1186
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• 2016

무선 통신 환경에서 위치기반서비스를 이용하기 위해서는 상대거리 측정기술이 중요하다. 본 논문에서는 비동기식 주파수 다중 분할(: FDD) 방식을 사용하는 통신환경에서 위치측정을 위한 내 외부 인프라 사용이 불가할 때, 물리계층의 프레임 구조를 활용한 상대거리 측정을 위한 방안을 제시한다. 제안된 방식은 연속적인 거리측정이 가능하며, 실험을 통해 평균 10m 이하의 측정 정확도를 확인하였다.

• 설비공학논문집
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• 제9권1호
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• pp.14-22
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• 1997

The position of propeller fan from duct inlet is one of basic parameters for the design of propeller fan. To investigate the effect of its position on fan characteristics, the inlet flow fields and relative flow angles were measured by a 5-hole pitot tube. The experimental results indicate that the ratio of radial flow introduced from propeller circumference to total inlet flow increases with the increase of propeller distance from duct inlet. When fan operates without duct, the total flow rate and the radial flow ratio are higher than those of any other positions of propeller relative to duct inlet. The radial flow ratio decreases as a flow coefficient and the propeller distance decrease. Therefore the front flow fields can be adjusted in some extent by varying the propeller distance according to a fan loading. The inlet flow angles are decreasing a little as a rotational speed and the propeller distance decrease. In the present case it was judged that the deviation angle of outlet flow became negative owing to a flow separation near a trailing edge.

• 한국광학회지
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• 제14권2호
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• pp.200-207
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• 2003

본 논문에서는 기존의 위상천이 디지털 홀로그래피에서 기준빔으로 사용되는 평면파 대신 보다 일반적인 구면파를 이용하여 3차원 공간상에 위치한 두 물체점들 사이의 상대적인 거리를 측정하는 새로운 시스템 및 알고리듬을 제안한다. 본 논문에서는 이러한 시스템에 대한 모의실험 및 광학실험을 실시하였다. 이러한 시스템에서는 홀로그램 기록에 사용된 기준빔의 정확한 정보를 알고 있지 않더라도 3차원 공간상의 두 물체점들 사이의 상대적인 거리를 정확하게 측정할 수 있다. 본 논문에서는 광학실험을 통하여 약 300 cm 거리에서 서로 0.5 cm 떨어진 두 물체점들 사이의 상대적인 거리를 10% 미만의 오차로 측정하였다.