• 한국항행학회논문지
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• 제20권5호
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• pp.401-407
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• 2016

본 논문에서는 태양광 장기체공 무인기의 전력모델을 포함한 3차원 경로계획과 유도에 대하여 기술한다. 본 논문에서 사용한 Dubins curve는 계산속도가 빨라 경로계획에 곧바로 적용이 가능하다는 장점이 있다. 하지만 Dubins curve의 경로생성 문제는 2차원 평면에서 정의되기 때문에 실제 항공기의 경로계획을 위해 Randal W. Beard에 의해 수행된 비행 경로각의 한계를 고려하여, 고도 차이에 따라 선회경로를 추가하는 방식의 3차원 Dubins 경로생성 알고리즘을 활용하였다. 본 논문에서 사용한 항공기 모델은 Aileron이 없기 때문에 Rudder를 사용하여 횡축 방향 제어기를 설계하였으며, 비선형 경로추종 유도기법을 사용하여 경로추종 시뮬레이션을 수행하였다. 고도조건에 따른 예제를 생성하였으며, 시뮬레이션 결과 생성된 경로를 잘 추종하는 것을 확인하였다. 마지막으로 태양에너지 수율에 대한 계산식을 통해 태양광 장기체공 무인기의 전력 시스템을 모델링하여 48시간 연속비행 시뮬레이션을 실시하였고, 이에 대한 시뮬레이션 결과를 제시하였다.

• 항공우주시스템공학회지
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• 제14권2호
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• pp.1-11
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• 2020

Detecting obstacles and generating a suitable path to avoid obstacles in real time is a prime mission requirement for UAVs. In areas, close to buildings and people, detecting obstacles in the path and estimating its own position (egomotion) in GPS degraded/denied environments are usually addressed with vision-based Simultaneous Localization and Mapping (SLAM) techniques. This presents possibilities and challenges for the feasible path generation with constraints of vehicle dynamics in the configuration space. In this paper, a near real-time feasible path is shown to be generated in the ORB-SLAM framework using a chain-based path planning approach in a force field with dynamic constraints on path length and minimum turn radius. The chain-based path plan approach generates a set of nodes which moves in a force field that permits modifications of path rapidly in real time as the reward function changes. This is different from the usual approach of generating potentials in the entire search space around UAV, instead a set of connected waypoints in a simulated chain. The popular ORB-SLAM, suited for real time approach is used for building the map of the environment and UAV position and the UAV path is then generated continuously in the shortest time to navigate to the goal position. The principal contribution are (a) Chain-based path planning approach with built in obstacle avoidance in conjunction with ORB-SLAM for the first time, (b) Generation of path with minimum overheads and (c) Implementation in near real time.

• 로봇학회논문지
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• 제18권3호
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• pp.251-259
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• 2023

In the path traveling of differential-drive robots, the steering controller plays an important role in determining the path-following performance. When a robot with a pure-pursuit algorithm is used to continuously drive a right-angled driving path in an unstructured environment without turning in place, the robot cannot accurately follow the right-angled path and stops driving due to the ground and motor load caused by turning. In the case of pure-pursuit, only the current robot position and the steering angle to the current target path point are generated, and the steering component does not reflect the speed plan, which requires improvement for precise path following. In this study, we propose a driving algorithm for differentially driven robots that enables precise path following by planning the driving speed using the radius of curvature and fusing the planned speed with the steering angle of the existing pure-pursuit controller, similar to the Model Predict Control control that reflects speed planning. When speed planning is applied, the robot slows down before entering a right-angle path and returns to the input speed when leaving the right-angle path. The pure-pursuit controller then fuses the steering angle calculated at each path point with the accelerated and decelerated velocity to achieve more precise following of the orthogonal path.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2022년도 추계학술대회
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• pp.351-356
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• 2022

선박의 운항 경로를 생성하기 위해 사용되는 경로 계획 방법 중, 그래프 기반 탐색 방식은 간결하고 최적해를 보장한다는 장점이 있어 널리 사용되고 있다. 그래프 기반 탐색 방식을 접안 경로 계획에 적용하는 경우, 추종 적합성을 필수적으로 고려 해야 한다. 그 이유는 접안 시 경로 이탈은 접안 시설과의 충돌로 이어질 수 있으므로, 경로의 이탈이 최소화하는 결과를 생성하는 것이 필요하다. 하지만 그래프 탐색 기반 접안 경로 계획의 기존 연구는 접안 시설 직전의 변침이 많은 결과를 생성하기 때문에 실제 운항 환경에 적용하는데 위험이 존재한다. 따라서 본 논문에서는 경로 추종에 적합한 비용 함수를 개발하고, 이를 적용한 3D A* 알고리즘을 제안한다. 또, 실제 운항 환경에 대한 적합성을 평가하기 위해서 유인 운항으로 수집한 데이터의 항적과 알고리즘의 경로 생성 결과를 비교한다.

• 한국산업융합학회 논문집
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• 제19권2호
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• pp.75-80
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• 2016

This study proposes a efficient technology to control the optimal trajectory planning and real-time implementation method which can perform autonomous travelling for unmaned factory automation. Online path planning should plan and execute alternately in a short time, and hence it enables the robot avoid unknown dynamic obstacles which suddenly appear on robot's path. Based on Route planning and control algorithm, we suggested representation of edge cost, heuristic function, and priority queue management, to make a modified Route planning algorithm. Performance of the proposed algorithm is verified by simulation test.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2011년도 추계학술대회
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• pp.188-191
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• 2011

Path finding and path planning is crucial in today's world where time is an extremely valuable element. It is easy to plan the optimum path to a destination if provided a map but the same cannot be said for an unknown and unexplored environment. It will surely be exhaustive to search and explore for paths to reach the destination, not to mention planning for the optimum path. This is very much similar to finding for an exit of a maze. A very popular competition designed to tackle the maze solving ability of autonomous called Micromouse will be used as a guideline for us to design our maze. There are numerous ways one can think of to solve a maze such as Dijkstra's algorithm, flood fill algorithm, modified flood fill algorithm, partition-central algorithm [1], and potential maze solving algorithm [2]. We will analyze these algorithms from various aspects such as maze solving ability, computational complexity, and also feasibility to be implemented.

• 한국군사과학기술학회지
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• 제16권6호
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• pp.719-725
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• 2013

In this paper, we propose a local path planning method based on RANGER algorithm and autonomy manager for autonomous navigation of UGV in urban environment. LPP method is designed to generate the local path in sensing area by using lane and curb of pavement and autonomy manager is designed to make a decision which transit the status of LPP component to a proper status for current navigation environment. A field test is conducted with scenarios in real urban environment in which crossroad, crosswalk and pavement are included and the performance of proposed method is validated.

• 국제학술발표논문집
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.111-113
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• 2015

Floats are used by the parties involved in a construction project. The owner may use float by changing order(s) or by executing risk avoidance plan; the contractor may use it for leveling resources or substituting activities' construction methods to reduce costs. Floats are accepted either just as by-product obtained by critical path method(CPM) scheduling or as asset having significant value. Succinctly, existing studies involved in float value does not consider its' changes on project time domain. It is important to identify float ownership and to quantify its' corresponding values. This paper presents a method that quantifies float value of money that changes over project execution. The method which accurately computes the monetary value of float may contributes to resolve conflicts relative to float ownership and/or delay issues among project participants. It compares the difference between the monetary value of total float - on non-critical path in each and every schedule update. It makes use of critical path method (CPM) and commercial software with which practitioners are already familiar.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(5)
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• pp.161-164
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• 2001

In this paper, we has been studied self controlled mobile robot system with CCD camera. This system consists of TMS320F240 digital signal processor, step motor, RF module and CCD camera. we used wireless RF module for movable command transmitging between robot and host PC. This robot go straight until 95 percent filled screen from input image. And the robot recognizes obstacle about 95 percent filled something, so it could avoid the obstacle and conclude new path plan.

• 융합정보논문지
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• 제8권5호
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• pp.251-261
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• 2018

중국은 ICT 기술의 발전에 힘입어 스마트 농업분야에서 선진국을 급격히 추격하고 있다. 본 논문에서는 추격이론을 이용하여, 중국의 양대 국가 전략인 중국제조2025와 일대일로 전략이 스마트농업을 발전시키는데 있어서 어떻게 "기회의 창"을 제공하는지 분석하고자 한다. 시간 차원의 기술 선진화 전략인 '중국제조2025'와 공간 차원의 시장 확대 전략인 '일대일로' 정책이 T자형 상승 작용을 이루어 스마트 농업의 발전을 이끌고 있음을 단계 생략형, 경로 창출형, 경로 추종형 3가지 유형으로 나누어 설명하였다. 한국 스마트 농업의 주요 수출 시장이며, 글로벌 시장에서 강력한 경쟁자인 중국 스마트 농업에 대한 이해를 통해 한국 스마트 농업의 해외진출 전략에 대한 시사점을 도출하였다.