• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.1002-1012
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• 2003

An algorithm is suggested for collision avoidance of two-arm robot manipulator using redundancy. End-effectors of each redundant arm should move along each prescribed straight path to complete the given task, while avoiding collision with each other. Self-motion, considered as motion of each axis not to change the position and orientation of end-effector, is utilized in order to solve this problem. At each sampling time, self-motion is executed with the view to making farther between the links of each arm. Simulation results for two-arm robot manipulator, which has 9-d.o.f. respectively, are illustrated to show the performance of the algorithm.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.11a
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• pp.278-280
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• 2000

본 논문에서는 경로계획 알고리즘으로 사용한 거리변환 경로곡선상에 중간경유점을 설정한후 이를 최적화시켜 각 이동로봇의 주행경로를 최적화 하였고, 로봇간의 우선 순위를 설정하여 원활한 충돌회피가 이루어지도록 하였으며, 각 로봇은 충돌회피 후에도 중간 경유점 까지 최단거리로의 주행이 이루어지도록 하였다. 또한 기존에 제시된 방법에 외길 입구에 경고 지점을 지정함으로써 외길에서의 상호충돌을 방지하는 효과를 주었다. 이로써 로봇간의 우선 순위의 설정으로 인하여 생기는 시간 지연을 해소시키는 효과를 가져올 수 있었다. 로봇간의 우선순위를 설정함에 있어서 또다른 변수를 추가시킴으로 로봇이외의 움직이는 장애물에 대해서도 고려하도록 하였다. 위와 같이, 본 논문에서는 여러대의 이동로봇을 고정된, 움직이는 장애물이 있는 환경하에서 장애물 회피시마다 최단경로로 주행하여 주어진 목표점까지 이동시키는 경로계획에 관하여 연구하였다.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1833-1834
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• 2008

본 논문에서는 다수의 AGV를 운용하는 물류자동화창고에서 최단경로가 배정된 AGV의 주행도중 발생하는 충돌 및 교착 상태를 예측하고 이를 회피하는 알고리즘을 개발하고자 한다. 충돌 및 교착 상태는 최단 경로와 경로 점유시간을 비교함으로써 예측하고 이를 경로 선입에 따른 우선권 및 지연시간에 따른 우선권에 따라 회피할 AGV를 선정함으로써 충돌 회피에 따른 AGV의 총 운행시간을 최소화한다.

• Journal of Advanced Navigation Technology
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• v.16 no.2
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• pp.197-203
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• 2012

In this paper, study the substantial issues which occurs upon free flight environment by performing separation assurance under multiple conflict(over 3 Aircraft), recovery en route under the terms of time constrains and fixed way point after the conflict avoidance, correlations between conflict detection distance and separation assurance by utilizing Autonomous flight algorithm. Result of this experiment demonstrates that the extension of detection distance is advantageous to solution of separation assurance and enhancing of flight efficiency, choose to maneuver by applying time constrain terms and fixed way point according to the situation of conflict prediction in case of recovery maneuver after the conflict avoidance. And separation assurance can be solved by applying 2 degrees or more of bank angle. When choosing the optimal bank angle could be drastically improved flight efficiency.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.05a
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• pp.311-313
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• 2018

해양안전심판원의 해양사고 통계자료에 따르면 기관손상 등을 제외한 해양사고 중 충돌사고의 비중은 가장 높고, 대부분의 충돌사고는 경계소흘 등 운항과실이 약 90%를 차지한다. 본 연구에서는 운항자의 항행 안전을 지원하고자 육상 무선 통신기술을 이용하여 중소형 선박의 충돌예방 시스템을 최종적으로 개발하기 위해 먼저 소형어선(30톤미만) 운항자의 요구분석을 수행하였다. 분석을 통해 충돌회피거리, 당직자 배치, 긴급피항시 필요시간, 충돌 및 경보시스템 개발에 필요한 사항 등을 도출하였다. 향후 이를 바탕으로 해상에서의 선박충돌 예방을 위한 신뢰성 높은 충돌경보 알고리즘을 개발 적용하는 등 사용자 편의적인 충돌경보 시스템을 개발하고자 한다.

• Journal of the Korean Society for Railway
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• v.10 no.3 s.40
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• pp.337-342
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• 2007

소형궤도 차량 시스템(PRT: Personal Rapid Transit)은 짧은 거리에 비교적 많은 승객을 수송하기 위하여 매우 짧은 차간 간격을 요구하며 또한 차량 간의 충돌을 피하기 위해서 매우 정확한 차량 속도제어 알고리즘을 필요로 한다. 본 논문에서는 소형궤도차량 시스템의 차량의 충돌회피 알고리즘 개발을 위한 장치의 구성에 대해서 다룬다. 개발 장치는 모의 차량, 중앙제어 시스템, 모의지상설비, 모니터링 장치로 구성되며, 설계된 알고리즘의 모의시험을 위해서 Labview Simulation Interface Toolkit과 Matlab/Simulink가 결합된 모의시험 환경을 이용한다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1939-1946
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• 2012

USNs (Ubiquitous Sensor Networks) such as IEEE 802.15.4 ZigBee network share ISM (Industrial, Scientific, and Medical) frequency band with WiFi networks. Once both networks operate in a region, packet collision may happen because of frequency overlapping. To assure this possibility, we conducted experiments where WiFi and ZigBee communication networks had been installed in an area. As a result of the test, successful data transmission rate were reduced due to the frequency overlapping between a WiFi communication channel and a ZigBee communication band. To cope with this problem, we propose a collision avoidance algorithm. In the proposed algorithm, if frequency collision is sensed, new communication channel with different frequency band is allocated to each node. Performance of the proposed frequency collision avoidance algorithm was tested and the results were described.

• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.475-480
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• 2004

Author presented some study with regard to “automatic control for ship collision avoidance system” before. Those papers are to deal with unsolved problem,; in the previous study. In this paper, two issues relating to ship collision avoidance were investigated. One is to suggest a new algorithm of avoidance of a group ship. This algorithm is useful when a ship takes avoiding action for a group fish boats and a group of merchant vessels. In the stage of taking avoidance action, newly-developed algorithm was used. the other is to develop a unified model of collision risk. Generally collision risk changes according to various type of encounters. The new model is to take into account of these situations. The above-mentioned algorithm and model were verified through simulation under various encounters between ships.

• Journal of Advanced Navigation Technology
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• v.15 no.6
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• pp.986-993
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• 2011

In this paper we consider the problem of the existing TCAS-II systems that fail to be satisfactory solution to mid-air collisions (MACs) and near mid-air collisions (NMACs or near misses). This is attributed to the fact that the earlier studies on the collision avoidance mainly have focused on determination logic of avoidance direction and vertical speed, reversal of the avoidance direction, multiple aircraft geometry, and availability in certain air spaces. But, the influence of sensor measurement errors on the performance of collision avoidance was not properly taken into account. Here we propose a new TCAS algorithm by using Kalman filter instead of '${\alpha}-{\beta}$' tracker to improve the avoidance performance under the influence of barometric sensor errors due to air-temperature, pressure leaks, static source error correction, etc.

• Journal of Aerospace System Engineering
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• v.15 no.1
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• pp.102-110
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• 2021

Recently, multi-copters equipped with various collision avoidance sensors have been introduced to improve flight stability. LiDAR is used to recognize a three-dimensional position. Multiple cameras and real-time SLAM technology are also used to calculate the relative position to obstacles. A three-dimensional depth sensor with a small process and camera is also used. In this study, a small collision-avoidance multi-copter system capable of in-door flight was developed as a platform for the development of collision avoidance software technology. The multi-copter system was equipped with LiDAR, 3D depth sensor, and small image processing board. Object recognition and collision avoidance functions based on the YOLO algorithm were verified through flight tests. This paper deals with recent trends in drone collision avoidance technology, system design/manufacturing process, and flight test results.