• 대한조선학회논문집
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• 제60권6호
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• pp.473-481
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• 2023

In this study, a simulation system was developed to verify autonomous navigation algorithm in complex maritime traffic areas. In particular, real-world maritime traffic scenario was applied by considering near real-time maritime traffic information provided by Korean e-Navigation service. For this, a navigation simulation system of Unmanned Surface Vehicle (USV) was integrated with an e-Navigation equipment, called Electronic Chart System (ECS). To verify autonomous navigation algorithm in the simulation system, initial conditions including initial position of an own ship and a set of paths for the ship to follow are assigned by an operator. Then, considering real-world maritime traffic information obtained from the service, the simulation is implemented in which the ship repeatedly travels by avoiding surrounding obstacles (e.g., approaching ships). In this paper, the developed simulation system and its application on verification of the autonomous navigation algorithm in complex maritime traffic areas are introduced.

• Journal of Positioning, Navigation, and Timing
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• 제12권4호
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• pp.335-342
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• 2023

Lunar Navigation Satellite System refers to a constellation of satellite providing PNT services on the moon. LNSS consists of main satellite and navigation satellites. Navigation satellites orbiting around the moon and a main satellite moves the area between the moon and the L2 point. The navigation satellite performs the same role as the Earth's GNSS satellite, and the main satellite communicates with the Earth for time synchronization. Due to the effect of the non-uniform shape of the moon, it is necessary to focus on the influence of the lunar gravitational field when designing the orbit simulation for navigation satellite. Since the main satellite is farther away from the moon than the navigation satellite, both the earth's gravity and the moon's gravity must be considered simultaneously when designing the orbit simulation for main satellite. Therefore, the main satellite orbit simulation must be designed through the three-body problem between the Earth, the moon, and the main satellite. In this paper, the orbit simulation tool for main satellite and navigation satellite required for LNSS was designed. The orbit simulation considers the environment characteristics of the moon. As a result of comparing long-term data (180 days) with the commercial program GMAT, it was confirmed that there was an error of about 1 m.

• 한국시뮬레이션학회논문지
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• 제19권3호
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• pp.127-135
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• 2010

최근의 현대화된 다양한 항해장비들로 인해 선박에 있는 항해사들은 위험상황 인식에 도움이 될 수 있는 정보들을 획득할 수 있게 되었다. 하지만, 이러한 유용한 도구들에도 불구하고 항해사들은 여전히 안전항행을 위한 의사결정에 어려움을 겪고 있는데, 이는 다양한 장비들이 제공하는 선박 내 외 상황에 관한 많은 양의 데이터를 지속적으로 관찰해야 한다는 항해사의 부담과 여러 장비 간 정보의 불일치성 때문이다. 실제로, 많은 해양 사고가 항해사의 부주의에 의해 일어나고 있다는 것이 이미 잘 알려져 있다. 따라서, 항행 상황의 일부 정보만을 제공하는 보조 장비를 넘어서 항해사의 의사결정을 도울 수 있는 지원도구가 요구되고 있다. 시뮬레이션은 의사결정을 지원 할 수 있는 기술 중 하나며, 선박에서의 실시간 주변상황에 대한 종합적인 평가 및 예측 가능한 시스템은 항해사의 안전항행에 대한 의사결정에 도움을 줄 수 있다. 이 논문은 선박을 위한 항행안전정보 시스템에서의 위험 상황 예측을 위한 시뮬레이션 방안에 관한 연구로서, 다양한 지식 베이스 및 이산 사건 시뮬레이션 방식을 활용한 시스템 전체 구성 방법을 제안하고 제한된 항행상황 시나리오에서의 구성 요소들의 예시를 통해 시스템의 타당성을 보인다.

• 한국해양공학회지
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• 제28권6호
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• pp.566-573
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• 2014

This paper presents the results of an integrated navigation performance analysis for selecting the sensor of an unmanned underwater vehicle (UUV) using Monte Carlo numerical simulation. An inertial measurement unit (IMU) and Doppler velocity log (DVL) are considered to build the integrated navigation system. The position error and price of the sensor are selected as performance indices to evaluate the volunteer integrated navigation systems. Monte-Carlo simulation is introduced to analyze the circular error probability (CEP) and its variance. Simulation results provide the proper sensor combination for integrated navigation in relation to the performance and price.

• 한국군사과학기술학회지
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• 제21권3호
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• pp.349-360
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• 2018

This paper proposes various methods for constructing a HWIL simulation system including Inertial Navigation System(INS) and Guidance Control Unit(GCU) under the assumption that the INS identifies the initial attitude of an aviation body through its own alignment and that it is a package consisting of an inertial sensor and a navigation computation module. This paper also presents a real-time computing technology and a way to calculate the command of the Flight Motion System(FMS) analogous to the acutal flight environment. The proposed HWIL simulation system is constructed by applying the above-mentioned methods and the results of running a series of simulations confirm high effectiveness and usefulness of the system. Finally, minor error factors that could be acquired only in HWIL simulation Environment are analyzed.

• 한국정보통신학회논문지
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• 제23권12호
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• pp.1700-1709
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• 2019

최근, 선박의 안전항해를 지원하기 위한 시스템(서비스)의 개발을 위해 여러 연구가 진행되고 있으며, 이들 연구에서는 개발한 시스템의 유용성 검증 및 효과도 평가에 공통적인 어려움을 겪고 있다. 본 논문에서는 이러한 문제를 해결하기 위해 DEVS 형식론 기반 선박 항해 모델링 및 시뮬레이션 기법을 제안한다. 선행연구에 이어 국제해상충돌예방규칙과 관련된 내용을 분석 및 도출하여 의사결정을 위한 항해사 및 조타수 에이전트를 모델링하고, 실제 선박의 운동특성을 반영하기 위한 추정 및 보간 기법을 제안한다. 또한, 설계한 내용을 반영하여 선박 항해 시뮬레이션 시스템을 구현하고, 개발한 시스템의 유용성을 검증하기 위한 다섯 가지 충돌회피 시나리오를 개발한다. 그 후, 각 시나리오에 따른 시뮬레이션을 수행하고 결과를 재구성하여 제시한다. 이를 통해 시뮬레이션 아키텍처 내에서 선박 구성요소 및 에이전트 모델이 유기적으로 결합하여 충돌회피 의사결정 및 항해 시뮬레이션이 가능함을 확인하였다.

• Journal of Positioning, Navigation, and Timing
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• 제5권2호
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• pp.97-107
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• 2016

Military Autonomous Underwater Vehicle (AUV) is utilized to search a mine under the sea. This paper presents design and performance verification of real-time hybrid navigation system for AUV. The navigation system uses Doppler Velocity Log (DVL) integration method to correct INS error in underwater. When the AUV is floated on the water, the accumulated error of navigation algorithm is corrected using position/velocity of GPS. The navigation algorithm is verified using 6 Degree Of Freedom (DOF) simulation, Program In the Loop Simulation (PILS). Finally, the experiments are performed in real sea environment to prove the reliability of real-time hybrid navigation algorithm.

• 전기학회논문지
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• 제61권3호
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• pp.479-484
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• 2012

Geometric effect of landmarks to the navigation error is investigated in the two-dimensional line-of-sight measurement based vision navigation system. DOP is derived between line-of-sight measurement error and navigation solution error. For cases of three landmarks in an area, variations of the DOP were observed through computer simulations. Vision navigation system experiments were performed for the cases. Simulation and experimental results show that navigation solution errors have similar trend to DOP values of the simulation.

• 전기학회논문지
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• 제63권1호
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• pp.123-131
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• 2014

An INS/vision integrated navigation algorithm is proposed for environments with insufficient number of landmarks. In the proposed algorithm, the raw measurements on the focal plane are directly used in order to cope with the situation where the number of landmarks are not sufficient. In addition to this, the combination of landmarks, which has smallest value of DOP, is used in the update of measurement in order to improve navigation performance. In order to evaluate the performance of the proposed integrated navigation system, Monte-Carlo simulation and van test was performed. The results of the simulation and experiment show that the proposed navigation system gives better navigation performance than an INS/vision integrated navigation system which does not use the raw measurements on the focal plane and the navigation system provides navigation solutions even in environments with insufficient number of landmarks.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.968-974
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• 2006

We are moving into the era of ubiquitous computing. Ubiquitous Sensor Network (USN) is a base of such computing paradigm, where recognizing the identification and the position of objects is important. For the object identification, RFID tags are commonly used. For the object positioning, use of sensors such as laser and ultrasonic scanners is popular. Recently, there have been a few attempts to apply RFID technology in robot localization by replacing the sensors with RFID readers to achieve simpler and unified USN settings. However, RFID does not provide enough sensing accuracy for some USN applications such as robot navigation, mainly because of its inaccuracy in distance measurements. In this paper, we describe our approach on achieving accurate navigation using RFID. We solely rely on RFID mechanism for the localization by providing coordinate information through RFID tag installed floors. With the accurate positional information stored in the RFID tag, we complement coordinate errors accumulated during the wheel based robot navigation. We especially focus on how to distribute RFID tags (tag pattern) and how many to place (tag granularity) on the RFID tag-floor. To determine efficient tag granularities and tag patterns, we developed a simulation program. We define the error in navigation and use it to compare the effectiveness of the navigation. We analyze the simulation results to determine the efficient granularities and tag arrangement patterns that can improve the effectiveness of RFID navigation in general.