• 제목/요약/키워드: Obstacle problems

검색결과 237건 처리시간 0.033초

수중비행체의 자율제어를 위한 지능형 3-D 장애물회피 알고리즘 (Intelligent 3-D Obstacle Avoidance Algorithm for Autonomous Control of Underwater Flight Vehicle)

  • 김현식;진태석;서주노
    • 한국지능시스템학회논문지
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    • 제21권3호
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    • pp.323-328
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    • 2011
  • 실제 시스템 적용에 있어서, 수중비행체(Underwater Flight Vehicle : UFV)의 자율제어(autonomous control)를 위한 3-D 장애물회피(obstacle avoidance) 시스템은 다음과 같은 문제점들을 가지고 있다. 즉, 소나(sonar)는 지역적 탐색영역 내에서 장애물의 거리(range)/방위(bearing) 정보를 제공하며, 자율수중운동체(Autonomous Underwater Vehicle : AUV) 관점에서 에너지 소비 및 음향학적 소음이 적은 시스템을 필요로 하며, 최대 피치 및 심도와 같은 UFV 운용 제약조건을 가진다. 나아가, 구조와 파라메터의 관점에 있어서 용이한 설계 절차를 요구한다. 이 문제를 해결하기 위해서 진화 전략(Evolution Strategy : ES) 및 퍼지논리 제어기(Fuzzy Logic Controller : FLC)를 이용하는 지능형 3-D 장애물회피 알고리즘이 제안되었다. 제안된 알고리즘의 성능을 검증하기 위해 UFV의 3-D 장애물회피가 수행되었다. 시뮬레이션 결과는 제안된 알고리즘이 실제 시스템에 존재하는 문제점들을 효과적으로 해결하고 있음을 보여준다.

Virtual Bumper를 이용한 장애물감지에 관한 연구(I) (A Study of the Obstacle Detection System Using Virtual Bumper(1))

  • 최성락;김선호;박경택;유득신
    • 한국항해항만학회:학술대회논문집
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    • 한국항해항만학회 1999년도 추계학술대회논문집
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    • pp.315-320
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    • 1999
  • Obstacle Detection System(ODS) is a essential system for automated vehicle, such as AGV(Automatic Guided Vehicle), mobile robot. Automated vehicle must have a capability to detect and to avoid obstacles to guarantee a safe driving condition. To implement obstacle detection system, virtual bumper concept adapted. Like real bumper in a car, such as in the truck, it protects vehicle from collision using laser distance sensor. When an obstacle(such as other vehicle, building, etc) intrudes this virtual bumper area, a virtual force is calculated and produces necessary strategy to be able to avoid collision. In this paper, simplified virtual bumper concept is presented, and various problems when happens to implement are discussed.

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UAM 수직이착륙장(Vertiport)의 장애물제한표면 적용 기준에 대한 연구 (A Study on the Criteria for Applying the Obstacle Limitation Surface of the UAM Vertiport)

  • 유태정
    • 한국항공운항학회지
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    • 제31권1호
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    • pp.18-25
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    • 2023
  • In recent years, UAM (Urban Air Mobility) has emerged as a solution to these urbanization problems, and many related reports and diverse prospects have been reported. UAM flights are planned to take off and land at a Vertiport located in the city center and fly along a pre-established corridor. In order for UAM to operate safely in the city center, it must ensure a safe flight path that avoids the buildings in the city center and many surrounding obstacles. Therefore, in this study, we compared and examined the installation standards of the obstacle limitation surface necessary for UAM to take off and land safely at the Vertiport. First, we analyzed the helicopter obstacle limitation surfaces in Japan and overseas, and the UAM Vertiport installation standards and obstacle limitation surface application standards recently announced at the FAA and EASA. It identified differences and similarities between heliport and Vertiport, and considered improvements to domestic helicopter obstacle limitation surfaces and criteria that could meet FAA and EASA standards.

AGV 시스템의 장애물 검출을 위한 고속 스테레오 영상처리 기법 (Fast Stereo Image Processing Method for Obstacle Detection of AGV System)

  • 전성재;조연상;박흥식
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2004년도 추계학술대회 논문집
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    • pp.454-457
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    • 2004
  • AGV for FMS must be detected an obstacle. Therefore, many studies have been advanced, and recently, the ultra sonic sensor is used for this. However, the new method has to be developed because the ultra-sonic-sensor has many problems as a noise in factory, an directional error and detection of the obstacle size. So, we study the fast stereo vision system that can give more information to obstacles for intelligent AGV system. For this, the simulated AGV system was made with two CCD cameras in front to get the stereo images, and the threshold process by color information (intensity and chromaticity) and structure stereo matching method were constructed.

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가변트랙형 주행로봇의 장애물 탐지와 주행모드제어 (Obstacle Detection and Driving Mode Control for a Mobile Robot with Variable Single-tracked Mechanism)

  • 최근하;정해관;현경학;곽윤근
    • 한국정밀공학회지
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    • 제25권2호
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    • pp.65-71
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    • 2008
  • In this paper, we propose a new driving mode control algorithm for a mobile robot based on obstacle detection. The robot has a variable geometry single-tracked mechanism, so it can maximize a contact length with ground for the adaptability to off-road and puesue a stable system due to the lower center of gravity. However this robot system embodied passive type according to operator. In this reason, several problems are detected. So, this research presents a new method of obstacle detection using PSD infrared sensors and translates the variable tracks on the best suited driving mode actively. And experimental results about mentioned are presented.

Image-based Subway Security System by Histogram Projection Technology

  • Bai, Zhiguo;Jung, Sung-Hwan
    • 한국멀티미디어학회논문지
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    • 제18권3호
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    • pp.287-297
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    • 2015
  • A railway security detection system is very important. There are many safety factors that directly affect the safe operation of trains. Security detection technology can be divided into passive and active approaches. In this paper, we will first survey the railway security systems and compare them. We will also propose a subway security detection system with computer vision technology, which can detect three kinds of problems: the spark problem, the obstacle problem, and the lost screw problem. The spark and obstacle detection methods are unique in our system. In our experiment using about 900 input test images, we obtained about a 99.8% performance in F- measure for the spark detection problem, and about 94.7% for the obstacle detection problem.

퍼지 포텐셜 필드를 이용한 이동로봇의 동적 경로 계획 (Dynamic Path Planning for Mobile Robots Using Fuzzy Potential Field Method)

  • 우경식;박종훈;허욱열
    • 전기학회논문지
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    • 제61권2호
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    • pp.291-297
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    • 2012
  • In this paper, potential field algorithm was used for path planning in dynamic environment. This algorithm is used to plan a robot path because of its elegant mathematical analysis and simplicity. However, there are some problems. The problems are problem of collision risk, problem of avoidance path, problem of time consumption. In order to solve these problems, we fused potential field with fuzzy system. The input of the fuzzy system is set using relative velocity and location of robot and obstacle. The output of the fuzzy system is set using the weighting factor of repulsive potential function. The potential field algorithm is improved by using fuzzy potential field algorithm and, path planning in various environment has been done.

철도건널목 지장물·진입위반차량 검지시스템 및 4분할 차단 알고리즘 개발 (Development of Algorithms for Four-quadrant Gate System and Obstacle Detection Systems at Crossings)

  • 오주택;조한선;이재명;심규돈
    • 대한토목학회논문집
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    • 제26권3D호
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    • pp.367-374
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    • 2006
  • 본 연구에서는 국내 철도건널목의 지장물 검지 시스템 및 차단제어 시스템의 운영현황을 살펴봄으로써 기존 시스템의 문제점을 보완할 수 있는 새로운 건널목 제어시스템 및 알고리즘을 제시한다. 국내 건널목 제어시스템의 경우 차량 및 지장물 검지를 통해 단순 입구측 및 출구측을 제어하는 방식으로서 도로 교통과는 연계를 하지 못하고 있는 실정이다. 또한 검지시스템과 차단시스템의 신호연계체계의 미비로 인하여 비효율적이며 안전성이 결여된 건널목 운영을 보이고 있다. 본 연구에서는 보다 효율적인 건널목 운영을 위하여 지자계 검지센서와 레이저 검지센서를 통합한 철도 건널목 지장물 진입위반차량 검지시스템과 4분할차단기 알고리즘을 제시하였고, 현장시험을 통하여 본 연구에서 제시한 알고리즘의 신뢰성을 검증하였다. 그 결과 본 연구에서 개발되어진 시스템들은 철도 건널목 제어기기들간의 상호연계가 가능하며, 동시에 차량운전자의 운행 형태를 고려한 차단제어 방식으로 열차와의 충돌사고를 예방할 수 있으리라 기대되어진다.

APPROXIMATED SEPARATION FORMULA FOR THE HELMHOLTZ EQUATION

  • Lee, Ju-Hyun;Jeong, Nayoung;Kang, Sungkwon
    • 호남수학학술지
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    • 제41권2호
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    • pp.403-420
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    • 2019
  • The Helmholtz equation represents acoustic or electromagnetic scattering phenomena. The Method of Lines are known to have many advantages in simulation of forward and inverse scattering problems due to the usage of angle rays and Bessel functions. However, the method does not account for the jump phenomena on obstacle boundary and the approximation includes many high order Bessel functions. The high order Bessel functions have extreme blow-up or die-out features in resonance region obstacle boundary. Therefore, in particular, when we consider shape reconstruction problems, the method is suffered from severe instabilities due to the logical confliction and the severe singularities of high order Bessel functions. In this paper, two approximation formulas for the Helmholtz equation are introduced. The formulas are new and powerful. The derivation is based on Method of Lines, Huygen's principle, boundary jump relations, Addition Formula, and the orthogonality of the trigonometric functions. The formulas reduce the approximation dimension significantly so that only lower order Bessel functions are required. They overcome the severe instability near the obstacle boundary and reduce the computational time significantly. The convergence is exponential. The formulas adopt the scattering jump phenomena on the boundary, and separate the boundary information from the measured scattered fields. Thus, the sensitivities of the scattered fields caused by the boundary changes can be analyzed easily. Several numerical experiments are performed. The results show the superiority of the proposed formulas in accuracy, efficiency, and stability.

비례항법을 이용한 무인 항공기의 최적 충돌 회피 기동 (Proportional Navigation-Based Optimal Collision Avoidance for UAVs)

  • 한수철;방효충
    • 제어로봇시스템학회논문지
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    • 제10권11호
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    • pp.1065-1070
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    • 2004
  • Optimal collision avoidance algorithm for unmanned aerial vehicles based on proportional navigation guidance law is investigated this paper. Although proportional navigation guidance law is widely used in missile guidance problems, it can be used in collision avoidance problem by guiding the relative velocity vector to collision avoidance vector. The optimal navigation coefficient can be obtained if an obstacle if an obstacle moves at constant velocity vector. The stability of the proposed algorithm is also investigated. The stability can be obtained by choosing a proper navigation coefficient.