• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1752-1753
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• 2007

이동하고자 하는 경로에 자석 마커를 설치하고 마커의 자계를 인식하여 경로를 추종하는 이동 로봇의 경로 제어시스템이다. 마커설치 간격 확장에 따른 센서 배치를 제안하였다. 마커의 극성을 서로 약속된 방법으로 코드화 하여 설치하고, 경로 추적 중에도 마커의 자계 방향을 2진 코드로 인식하여 자계 경로로부터 경로 정보를 수신할 수 있도록 하였다. 소형 이동 로봇 실험 장치를 설계 제작하고 실험을 한 결과 제작된 이동 로봇은 마커로 만들어진 이동 경로를 중앙으로부터 오차 범위 이내에서 이동함을 확인하였고, 이동 경로의 일부 구간에서는 마커의 극배치를 이용한 코드를 주행 중에 정확히 인식함을 확인하였다.

• Journal of Ocean Engineering and Technology
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• v.23 no.6
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• pp.146-155
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• 2009

This paper considers the path tracking problem in a horizontal plane for underactuated (or non-holonomic) autonomous underwater vehicles (AUVs). Underwater mapping has been an important mission for AUVs. Recently, underwater docking has also become a main research field of AUVs. These kinds of missions basically require accurate attitude and trajectory control performance. However, the non-holonomic problem should be solved to achieve accurate path tracking for the torpedo-type of AUVs. In this paper, resolved motion and acceleration control (RMAC) is considered as a path tracking controller for an underactuated torpedo-shaped AUV, ISiMi. A set of numerical simulations is carried out to illustrate the effectiveness of the proposed RMAC scheme, and experimental data with ISiMi100 and discussions are presented.

• Journal of Auto-vehicle Safety Association
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• v.11 no.2
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• pp.17-22
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• 2019

This paper describes the tracking algorithm performance evaluation for autonomous vehicle using a safety envelope based path. As the level of autonomous vehicle technologies evolves along with the development of relevant supporting modules including sensors, more advanced methodologies for path generation and tracking are needed. A safety envelope zone, designated as the obstacle free regions between the roadway edges, would be introduced and refined for further application with more detailed specifications. In this paper, the performance of the path tracking algorithm based on the generated path would be evaluated under safety envelop environment. In this process, static obstacle map for safety envelope was created using Lidar based vehicle information such as current vehicle location, speed and yaw rate that were collected under various driving setups at Seoul National University roadways. A level of safety was evaluated through CarSim simulation based on paths generated with two different references: a safety envelope based path and a GPS data based one. A better performance was observed for tracking with the safety envelop based path than that with the GPS based one.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.1
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• pp.61-69
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• 2021

Recently, autonomous navigation technology is actively being developed due to the increasing demand of an unmanned surface vehicle(USV). Local planning is essential for the USV to safely reach its destination along paths. the dynamic window approach(DWA) algorithm is a well-known navigation scheme as a local path planning. However, the existing DWA algorithm does not consider path line tracking, and the fixed weight coefficient of the evaluation function, which is a core part, cannot provide flexible path planning for all situations. Therefore, in this paper, we propose a new DWA algorithm that can follow path lines in all situations. Fixed weight coefficients were trained using reinforcement learning(RL) which has been actively studied recently. We implemented the simulation and compared the existing DWA algorithm with the DWA algorithm proposed in this paper. As a result, we confirmed the effectiveness of the proposed algorithm.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.12
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• pp.981-988
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• 2021

This paper presents a decentralized guidance algorithm for swarm flight of fixed-wing UAVs (Unmanned Aerial Vehicles). Considering swarm flight missions, we assume four representative swarm tasks: gathering, loitering, waypoint/path following, and individual task. Those tasks require several distinct maneuvers such as path following, flocking, and collision avoidance. In order to deal with the required maneuvers, this paper proposes an integrated guidance algorithm based on vector field, augmented Cucker-Smale model, and potential field methods. Integrated guidance command is synthesized with heuristic weights designed for each guidance method. The proposed algorithm is verified through flight tests using up to 19 small fixed-wing UAVs.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.3
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• pp.264-273
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• 2010

In this work, autonomous formation flight tests of multiple UAVs are experimentally studied. After a guidance and control system for a UAV is designed and tested, PID formation controller for follower UAV is tested using longitudinal and lateral distance feedback. It is shown that more stable and efficient formation guidance system is obtained by using position and attitude of the leader aircraft, which is exploited to calculate virtual waypoint for follower. In order to improve transient response during turn, part of roll command of the leader is added to the guidance command. Finally, autonomous formation flight test results of 3 UAVs are shown by using the best guidance algorithm suggested.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1750-1751
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• 2007

이동하고자 하는 경로에 자석 마커를 설치하고 마커의 자계를 인식하여 경로를 추종하는 이동 로봇의 경로 제어시스템이다. 자석마커 간격 확장과 여러 환경에 따른 자계를 분석하기 위해 자동 자계 측정 장치를 제작하였고, 이를 이용한 실측을 통하여 지자기 제거를 확인하였다. 지자기가 제거된 마커 자기장 값의 정규화와 선형화를 통하여 이동 경로 상에서 위치 인식이 수월하도록 하였으며, 인식된 경로 정보로 이동 로봇의 경로 제어가 가능하도록 하였다.

• Tunnel and Underground Space
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• v.32 no.5
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• pp.298-311
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• 2022

Some problems, such as aging workers, a decreased population due to a low birth rate, and shortage of skilled workers, are rising in construction sites. Therefore research for smart construction technology that can be improved for productivity, safety, and quality has been recently developed with government support by replacing traditional construction technology with advanced digital technology. In particular, the motor grader that mainly performs road surface flattening is a construction machine that requires the application of automation technology for repetitive construction. It is predicted that the construction period will be shortened if the construction automation technology such as trajectory tracking, automation work, and remote control technology is applied. In this study, we introduce the hardware and software architecture of the smart motor grader to apply unmanned and automation technology and then analyze the traditional earthwork method of the motor grader. We suggested the application plans for the path pattern and blade control method of the smart motor grader based on this. In addition, we verified the performance of waypoint-based path-following depending on scenarios and the blade control's performance through tests.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.79-80
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• 2023

본 연구에서는 자율운항선박이 복잡한 항계 내에서 다양한 해상 객체와의 충돌을 회피하기 위하여 계층적 경로 생성 기법을 연계하는 프레임워크를 제안한다. 항계 내에는 항로를 항행하는 선박 외에도 정박 영역 내 정박 또는 묘박 중인 선박뿐만 아니라 항로 표지나 부표와 같은 정적 객체들이 다양하게 분포되어 있다. 자율운항선박의 효율적 운항을 위해서는 운항 중에 조우하게 되는 객체의 정적/동적 속성에 따라 경로 생성 기법이 달리 적용되어야 한다. 본 연구에서 제안한 경로 생성 프레임워크는 항계 내의 정적 객체나 항행 가항 영역 및 항행 불가항 영역 등에 대한 위치 정보들은 사전적 정보로 활용 가능하므로, 샘플링 기반의 전역 경로 생성 기법을 적용하여, 초기 출발지에서 최종 목적지까지의 예상 경로를 생성한다. 그리고 생성된 전역 경로를 추종하며 운항하는 과정에서 조우하게 되는 동적 객체들과의 조우 상황별 국제해상 충돌예방규칙(COLREGs)을 고려한 지역 경로를 생성한다. 샘플링 기반의 전역 경로와 국소 영역에서의 충돌 회피를 위한 지역 경로를 연계하기 위한 계층적 경로 생성 프레임워크를 설계하고, 수치 시뮬레이션을 통해 제안한 프레임워크의 유용성을 검증하였다.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.383-385
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• 1996

In this paper, the dynamic path-following using the path-observer is proposed to improve the stability when initial position errors are considered. The dynamic path-following without the path-observer cannot follow reference path when initial position errors are large, so we propose the path-observer method. Finally, the results of simulation will be described.