• 산업경영시스템학회지
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• 제34권3호
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• pp.24-34
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• 2011

An Unmanned Aerial Vehicle (UAV) is a powered pilotless aircraft, which is controlled remotely or autonomously. UAVs are an attractive alternative for many scientific and military organizations. UAVs can perform operations that are considered to be risky or uninhabitable for human. UA V s are currently employed in many military missions such as reconnaissance, surveillance, enemy radar jamming, decoying, suppression of enemy air defense (SEAD), fixed and moving target attack, and air-to-air combat. UAVs also are employed in a number of civilian applications such as monitoring ozone depletion, inclement weather, traffic congestion, and taking images of dangerous territory. For accomplishing the UAV's missions, guarantee of survivability should be preceded. The main objective of this study is to suggest a mathematical programming model and a $A^*PS$-PGA (A-star with Post Smoothing-Parallel Genetic Algorithm) for an UAV's path planning to maximize survivability. A mathematical programming model is composed by using MRPP (Most Reliable Path Problem) and TSP (Traveling Salesman Problem). A path planning algorithm for UAV is applied by transforming MRPP into SPP (Shortest Path Problem).

• Journal of Information Processing Systems
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• 제16권6호
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• pp.1324-1342
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• 2020

Various modified algorithms of rapidly-exploring random tree (RRT) have been previously proposed. However, compared to the RRT algorithm for collision avoidance with global and static obstacles, it is not easy to find a collision avoidance and local path re-planning algorithm for dynamic obstacles based on the RRT algorithm. In this study, we propose boundary-RRT*, a novel-algorithm that can be applied to aerial vehicles for collision avoidance and path re-planning in a three-dimensional environment. The algorithm not only bounds the configuration space, but it also includes an implicit bias for the bounded configuration space. Therefore, it can create a path with a natural curvature without defining a bias function. Furthermore, the exploring space is reduced to a half-torus by combining it with simple right-of-way rules. When defining the distance as a cost, the proposed algorithm through numerical analysis shows that the standard deviation (σ) approaches 0 as the number of samples per unit time increases and the length of epsilon ε (maximum length of an edge in the tree) decreases. This means that a stable waypoint list can be generated using the proposed algorithm. Therefore, by increasing real-time performance through simple calculation and the boundary of the configuration space, the algorithm proved to be suitable for collision avoidance of aerial vehicles and replanning of local paths.

• 한국멀티미디어학회논문지
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• 제25권2호
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• pp.237-246
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• 2022

Among the technologies of the 4th industrial revolution, drones that have grown rapidly and are being used in various industries can be operated by the pilot directly or can be operated automatically through programming. In order to be controlled by a pilot or to operate automatically, it is essential to predict and analyze the optimal path for the drone to move without obstacles. In this paper, after securing and analyzing the pilot training dataset through the unmanned aerial vehicle piloting training platform designed through prior research, the profile of the dataset that should be preceded to search and derive the optimal route of the unmanned aerial vehicle was designed. The drone pilot training data includes the speed, movement distance, and angle of the drone, and the data set is visualized to unify the properties showing the same pattern into one and preprocess the properties showing the outliers. It is expected that the proposed big data-based profile can be used to predict and analyze the optimal movement path of an unmanned aerial vehicle.

• 한국가시화정보학회지
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• 제17권1호
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• pp.85-92
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• 2019

Numerical visualization is conducted to confirm the variation of flow characteristics and pressure drop by the shape of channels on the cathode flow path in hydrogen fuel cells for unmanned aerial vehicles(UAVs). Generally, a light-weight fan is commonly used rather than a heavy air compressor at UAVS. However, in case of blower fan, a large pressure drop in the flow path causes the blocking of the oxygen supply to the fuel cell. Therefore, the uniformity of flow inside the cathode has to be achieved by changing the shape of the cathode. The flow channel, the duct shape, and the diameter of the fan are changed to optimize the flow path. As a result, it is confirmed that the optimal flow path can decrease the velocity difference between the center and outer flow by 1.8%. However, It should be noted that the channel size can increase the pressure drop.

• ETRI Journal
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• 제43권4호
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• pp.580-593
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• 2021

When operating in confined spaces or near obstacles, collision-free path planning is an essential requirement for autonomous exploration in unknown environments. This study presents an autonomous exploration technique using a carefully designed collision-free local planner. Using LiDAR range measurements, a local end-point selection method is designed, and the path is generated from the current position to the selected end-point. The generated path showed the consistent collision-free path in real-time by adopting the Euclidean signed distance field-based grid-search method. The results consistently demonstrated the safety and reliability of the proposed path-planning method. Real-world experiments are conducted in three different mines, demonstrating successful autonomous exploration flights in environment with various structural conditions. The results showed the high capability of the proposed flight autonomy framework for lightweight aerial robot systems. In addition, our drone performed an autonomous mission in the tunnel circuit competition (Phase 1) of the DARPA Subterranean Challenge.

• 한국멀티미디어학회논문지
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• 제25권8호
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• pp.1007-1021
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• 2022

Autonomous driving of unmanned aerial vehicles may have to pay expensive cost to create and switch new routes if unexpected obstacles exist or local map updates occured by the control system due to incorrect route information. Integrating digital twins into the path-following process requires more computing resources to quickly switch the wrong path to an alternative path, but it can quickly update the path during flight. In this study, we design a DEVS-based simulation environment which can modify optimized paths through short-term simulation of multi-virtual UAVs for applying digital twin concepts to path follow. Through simulation, we confirmed the possibility of increasing the mission stability of UAV.

• 대한임베디드공학회논문지
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• 제18권6호
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• pp.327-333
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• 2023

Existing studies on the UAV (Unmanned Aerial Vehicle)-based CPS (Cyber Physical System) environment lack forest fire monitoring and forest fire reconnaissance using real-world UAVs. So, it is necessary to monitor forest fires early through CPS based on real-world UAVs with high reliability and resource management efficiency. In this paper presents an MFG (Misstion File Generater) that automatically generates a flight path of an UAV for forest fire monitoring in a CPS environment. MFG generates flight paths based on a hiking trail with a high fire probability due to a true story of an entrant. We have confirmed that the flight path generated by MFG can be applied to the UAV. Also, we have verified that the UAV flies according to the flight path generated by MFG in simulation, with a negligible error rate.

• Journal of Information Processing Systems
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• 제14권6호
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• pp.1457-1463
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• 2018

In recent times, Natural User Interface/Natural User Experience (NUI/NUX) technology has found widespread application across a diverse range of fields and is also utilized for controlling unmanned aerial vehicles (UAVs). Even if the user controls the UAV by utilizing the NUI/NUX technology, it is difficult for the user to easily control the UAV. The user needs an autopilot to easily control the UAV. The user needs a flight path to use the autopilot. The user sets the flight path based on the waypoints. UAVs normally fly straight from one waypoint to another. However, if flight between two waypoints is in a straight line, UAVs may collide with obstacles. In order to solve collision problems, flight records can be utilized to adjust the generated path taking the locations of the obstacles into consideration. This paper proposes a natural path generation method between waypoints based on flight records collected through UAVs flown by users. Bayesian probability is utilized to select paths most similar to the flight records to connect two waypoints. These paths are generated by selection of the center path corresponding to the highest Bayesian probability. While the K-means algorithm-based straight-line method generated paths that led to UAV collisions, the proposed method generates paths that allow UAVs to avoid obstacles.

• 한국정보통신학회논문지
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• 제10권5호
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• pp.890-896
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• 2006

GPS 측량은 Multi-path 오차가 발생하기 때문에 도심지역이나 숲이 있는 항공사진에서는 지상기준점을 잡기 위해 GPS측량이 어렵다. 본 논문은 소규모 지역에서 3차원 정사사진 구현을 위한 GPS와 EDM의 적용에 관한 연구이다. 삼각점에서 연구대상지역에 대한 기준점을 내린 다음 EDM으로 정밀삼각측량으로 지상기준점을 선정하였다. 그리고 항공사진을 정사투영사진으로 변환하기 위해 획득된 지상기준점을 적용하였다. 그리고 연구대상지역에 대하여 항공정사사진을 이용한 3차원 모델링을 구현하여 향 후 추진될 3차원 GIS 구축을 위한 항공사진의 활용방안에 대해서 연구하였다. Multi-path 오차로 기인하는 GPS수신이 어려운 지점을 EDM을 이용하여 영상에서 균등히 분포된 지상기준점의 획득이 가능하였고 3차원 공간정보 자료구축에서 가장 기본이 되는 소규모 지역에서 항공사진의 활용이 가능할 것으로 판단되었다.

• 한국항행학회논문지
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• 제27권4호
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• pp.365-373
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• 2023

무인 항공기는 다양한 분야에서 널리 활용되고 있으며, 실시간 경로 재계획은 이들 기기의 안전성과 효율성을 향상하는 핵심 요소이다. 본 논문에서는 RRT*와 LOSPO를 기반으로 한 실시간 경로 재계획 기법을 제안한다. 제안된 기법은 먼저 RRT* 알고리즘을 활용하여 초기 경로를 생성하고, LOSPO를 이용하여 경로를 최적화한다. 또한 최적화된 경로를 궤적으로 변경하여 실제 시간과 항공기의 동적한계를 고려할 수 있다. 이 과정에서 환경 변화와 충돌 위험을 실시간으로 감지하고, 필요한 경우 경로를 재계획함으로써 안전한 운행을 유지한다. 이 방법은 시뮬레이션을 통한 실험을 통해 검증되었다. 본 논문의 결과는 무인 항공기의 실시간 경로 재계획에 관한 연구에 중요한 기여할 것으로 기대한다. 또한 이 기법을 다양한 상황에 적용함으로써 무인 항공기의 안전성과 효율성을 향상시킬 수 있다.