• 해양환경안전학회지
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• 제25권3호
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• pp.259-268
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• 2019

Even if only two ships are encountered, a collision may occur due to the mistaken judgment of the positional relationship. In other words, if an officer does not know a target ship's intention, there is always a risk of collision. In this paper, the experiments are conducted to investigate how the intention affects the action of collision avoidance in cooperative and non-cooperative situations. In non-cooperative situation, each ship chooses a course that minimizes costs based on the current situation. That is, it always performs a selfish selection. In a cooperative situation, the information is exchanged with a target ship and a course is selected based on this information. Each ship uses the Distributed Stochastic Search Algorithm so that a next-intended course can be selected by a certain probability and determines the course. In the experimental method, four virtual ships are set up to analyze the action of collision avoidance. Then, using the actual AIS data of eight ships in the strait of Dover, I compared and analyzed the action of collision avoidance in cooperative and non-cooperative situations. As a result of the experiment, the ships showed smooth trajectories in the cooperative situation, but the ship in the non-cooperative situation made frequent big changes to avoid a collision. In the case of the experiment using four ships, there was no collision in the cooperative situation regardless of the size of the safety domain, but a collision occurred between the ships when the size of the safety domain increased in cases of non-cooperation. In the case of experiments using eight ships, it was found that there are optimal parameters for collision avoidance. Also, it was possible to grasp the variation of the sailing distance and the costs according to the combination of the parameters, and it was confirmed that the setting of the parameters can have a great influence on collision avoidance among ships.

• 한국통신학회논문지
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• 제33권8B호
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• pp.657-666
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• 2008

The intersection collision avoidance service among various telematics application services is regarded as one of the most critical services with regard to safety. In such safety applications, real-time, correct transmission of service is required. In this paper, we study on efficient infrastructure architecture for intersection collision avoidance using a cooperative mechanism between vehicles and wireless infrastructure. In particular, we propose an infrastructure, called CISN (Cooperative Infrastructure associated with Sensor Networks), in which proper numbers of sensor nodes are deployed on each road, surrounding the intersection. In the proposed architecture, overall service performance is influenced by various parameters consisting of the infrastructure, such as the number of deployed sensor nodes, radio range and broadcast interval of base station, and so on. In order to test the feasibility of the CISN model in advance, and to evaluate the correctness and real-time transmission ability, an intersection sensor deployment simulator is developed. Through various simulations on several environments, we identify optimal points of some critical parameters to build the most desirable CISN.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1927-1932
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• 2003

In a previous study, the authors have proposed the Cooperative Collision Avoidance (CCA) method which enables mobile robots to cooperatively avoid collisions, by extending the concept of the Velocity Obstacle to multiple robot systems. The method introduced an evaluation function considering an operation objective so that each robot can choose the velocity which optimizes the function. As the evaluation function could be of an arbitrary type, this method is applicable to a wide variety of tasks. However, it complicates the optimization of the function especially in real-time. In addition, construction of the evaluation function requires an operation objective of the other robot which is very hard to obtain without communication. In this paper, the CCA method is improved considering such problems for implementation. To decrease computational costs, the previous method is simplified by introducing two essential assumptions. Then, by treating the desired direction of locomotion for each robot as the operation objective, an operation objective estimator which estimates the desired direction of the other robot is introduced. The only measurement required is the other robot's relative position, since the other information can be obtained through the estimation. Hence, communicational devices that are necessary for most other cooperative methods are not required. Moreover, mobile robots employing the method can avoid collisions with uncooperative robots or moving obstacles as well as with cooperative robots. Consequently, this improved method can be applied to general dynamic environments consisting of various mobile robots.

• 자동차안전학회지
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• 제11권3호
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• pp.19-29
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• 2019

Recently, autonomous vehicles have been studied actively. Autonomous vehicles can detect objects around them using their on board sensors, estimate collision probability and maneuver to avoid colliding with objects. Many algorithms are suggested to prevent collision avoidance. However there are limitations of complex and diverse environments because algorithm uses only the information of attached environmental sensors and mainly depends on TTC (time-to-Collision) parameter. In this paper, autonomous driving algorithm using I2V communication-based cooperative sensing information is developed to cope with complex and diverse environments through sensor fusion of objects information from infrastructure camera and object information from equipped sensors. The cooperative sensing based autonomous driving algorithm is implemented in autonomous shuttle bus and the proposed algorithm proved to be able to improve the autonomous navigation technology effectively.

• 한국전자파학회논문지
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• 제23권10호
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• pp.1173-1179
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• 2012

본 논문에서는 협력 무선 통신 시스템의 순방향 링크에서 각 이동국의 제한된 피드백 정보를 이용하여, 인접한 기지국들에서 동시에 전송되는 빔성형된 순방향 링크들 간의 간섭을 효과적으로 억제하는 충돌 회피 빔성형 기술을 제안한다. 제안하는 충돌 회피 빔성형 기술에서, 각 이동국은 서비스 기지국이 신호 전송을 위해 사용할 신호 가중치 벡터와 간섭 기지국이 해당 이동국에게 최대 간섭을 주는 주 간섭 가중치 벡터들에 대한 정보를 피드백한다. 또한, 클러스터 스케줄러는 각 기지국에서 사용하는 가중치들에 의해 성형되는 빔들 간의 충돌을 억제하도록, 동시에 데이터를 전송할 이동국들과 해당 이동국들이 사용할 빔성형 가중치들을 동시에 결정한다. 시뮬레이션을 통해 제안하는 충돌 회피 빔성형 기술이 기존의 기지국별로 빔성형을 수행하는 비 협력 빔성형 기술보다 높은 시스템 전송 용량을 제공할 수 있음을 보인다. 또한, 협력 공간 분할 다중 접속 기술과의 전송용량을 비교하여, 제안하는 충돌 회피 빔성형 기술과의 장단점을 비교 분석한다.

• 한국운동역학회지
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• 제29권2호
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• pp.97-104
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• 2019

Objective: The aim of this study was to investigate the strategies for avoiding moving and stationary walker using body segments during walking. Method: Ten healthy young adults (10 males, age: $24.40{\pm}0.49yrs$, height: $175.80{\pm}5.22cm$, body mass: $70.30{\pm}5.22kg$) participated in this study. Each participant was asked to perform a task to avoid collisions with another walker who was moving or stationary during walking on the 10 m walkway. Both walkers were performed at natural self-selected walking speed. Results: Medio-lateral avoidance displacement of the trunk and the pelvis were significantly increased when avoiding a stationary walker (p<.05). There were no significant differences in medio-lateral center of mass trajectory. Rotation angle of trunk, pelvis and foot on the vertical axis were significantly increased when avoiding a stationary walker (p<.05). Conclusion: Based on our results, when another walker moves continuously, the walker recognizes another walker as the object of social interaction and performs the avoidance strategies while expecting the cooperative distance. On the other hand, when another walker is stopped, it is determined that the walker has an obligation to avoid, and the walker performs a relatively safer avoidance strategy.

• 산업경영시스템학회지
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• 제22권50호
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• pp.33-44
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• 1999

This paper describes the Autonomous Vehicles (AV) which are operated for their own tasks. There are chances of conflict resolution such as sharing the same path which can lead to the risk of a collision. This research represents some ways of negotiating the conflict resolution by generating cooperative actions. Negotiation while traveling the path is accomplished by using priority and by announcing the start time of the task. When there is a risk of collision, the AV tries to dissolve the situation of conflict resolution by concurrently adjusting mutual speed and by performing the algorithm of passing. If the speed of the AV cannot be adjusted, it measures the distance between the counterpart of the AV and an obstacle along the path. Then it judges either to proceed by passing the counterpart of the AV or to turn back after observing the current circumstances. The performance of the algorithm described above was proven by a simulator.

• 한국ITS학회 논문지
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• 제18권6호
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• pp.176-190
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• 2019

최근 횡단보도 및 교차로에서 보행자 충돌사고 예방의 중요성이 증가하고 있다. C-ITS 서비스에서 이러한 사고를 줄이기 위하여 보행자 충돌방지 경고 서비스를 제시하고 있다. 그러나 현재 C-ITS 표준에 따른 보행자 충돌방지 경고 서비스는 현장의 카메라에서 보행자를 바로 검출하여 서비스를 제공하는 것이 아니라 관제 센터의 영상분석 서버에서 보행자를 검출하고 ITS 시스템과 연계하여 서비스를 제공하기 때문에 실시간성을 만족하기 어렵다. 본 논문에서는 엣지 카메라를 이용하여 현장에서 보행자를 검출하고 검출결과를 V2X 인프라를 통해 바로 운전자에게 제공하는 보행자 충돌방지 경고 시스템을 제안하고, 구현한 후 성능 평가를 시행하였다. 평가 결과, 최악의 상황에서도 보행자 충돌방지 경고 메시지를 C-ITS 표준에서 요구하고 있는 300ms 이내의 지연시간을 만족하여 전달할 수 있음을 확인하였다.

• 한국통신학회논문지
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• 제37권1B호
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• pp.1-8
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• 2012

차량 사용이 증가함에 따라 교통안전에 관한 문제가 심각해지고 있다. 이러한 문제점을 해결하기 위해 근래에는 차량에 통신 기술을 접목한 ITS (Intelligent Transportation System)기술로 차량의 안전성을 강화하려는 연구가 진행되고 있다. 차량 안전 네트워크 규격인 WAVE는 방송형 멀티홉으로 전송하고 다중접속방법으로 CSMA/CA를 사용하므로 차량 수가 증가하면 빈번한 전송 시도로 인해 성능이 급격히 저하되는 특징이 있다. 본 연구에서는 이러한 문제를 해결하기 위해 메시지 전송차량과 수신차량의 위치관계를 이용하여 불필요한 메시지 전송을 줄이는 양방향 묵시적 수신확인 방안(TWIA: Two-Way Implicit Acknowledgement)을 제안한다. 제안한 TWIA는 전방과 후방의 차량으로부터 같은 메시지를 받으면 메시지 전달이 성공적인 것으로 간주하여 더 이상 재전송하지 않으므로 불필요한 메시지 전송을 줄인다. 실험을 통해 기존의 위험 경고 메시지 전송방안과 성능비교를 하였으며, 100대 차량을 기준으로 맨 뒤 차량까지의 전송 지연은 9%의 성능 개선이 되었고, 일정 구간 내에 모든 차량의 메시지 수신 성능은 0.7초 이내 수신 성공률이 12%가 개선되었다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 1996년도 추계학술대회발표논문집; 고려대학교, 서울; 26 Oct. 1996
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• pp.99-102
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• 1996

Research regarding the Autonomous Distributed & Cooperated System has not yet been defined because we need to apply the interdisciplinary approach before so. In this paper, we use a clear definition, compare characteristics of the Autonomous Distributed & Cooperated System and examine the possibility of an actualization through path planning of Autonomous AGV. We propose a new algorithm about the generation method of a moving path at the first stage and a cooperative action generation for a collision avoidance. Lastly, we performed simulation analysis of these two in order to confirm efficiency.