• 한국자동차공학회논문집
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• 제19권4호
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• pp.8-15
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• 2011

This paper proposes a real-time navigation algorithm which integrates the artificial potential field (APF) for an unmanned vehicle in the unknown environment. This approach uses repulsive potential function around the obstacles to force the vehicle away and an attractive potential function around the goal to attract the vehicle. In this research, laser range finder is used as range sensor. An obstacle detected by the sensor creates repulsive vector. Differential global positioning system (DGPS) and digital compass are used to measure the current vehicle position and orientation. The measured vehicle position is also used to create attractive vector. This paper proposes a new concept of potential field based navigation which controls unmanned vehicle's speed and steering. The magnitude of repulsive force based on the proposed algorithm is designed not to be over the magnitude of attractive force while the magnitude is increased linearly as being closer to obstacle. Consequently, the vehicle experiences a generalized force toward the negative gradient of the total potential. This force drives the vehicle downhill towards its goal configuration until the vehicle reaches minimum potential and it stops. The effectiveness of the proposed APF for unmanned vehicle is verified through simulation and experiment.

• 산업경영시스템학회지
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• 제47권2호
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• pp.147-154
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• 2024

This study focuses on the path planning algorithm for large-scale autonomous delivery using drones and robots in urban environments. When generating delivery routes in urban environments, it is essential that avoid obstacles such as buildings, parking lots, or any other obstacles that could cause property damage. A commonly used method for obstacle avoidance is the grid-based A* algorithm. However, in large-scale urban environments, it is not feasible to set the resolution of the grid too high. If the grid cells are not sufficiently small during path planning, inefficient paths might be generated when avoiding obstacles, and smaller obstacles might be overlooked. To solve these issues, this study proposes a method that initially creates a low-resolution wide-area grid and then progressively reduces the grid cell size in areas containing registered obstacles to maintain real-time efficiency in generating paths. To implement this, obstacles in the operational area must first be registered on the map. When obstacle information is updated, the cells containing obstacles are processed as a primary subdivision, and cells closer to the obstacles are processed as a secondary subdivision. This approach is validated in a simulation environment and compared with the previous research according to the computing time and the path distance.

• International Journal of Aeronautical and Space Sciences
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• 제18권4호
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• pp.719-728
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• 2017

This paper proposes a synthesis of new guidance law to generate an evasive maneuver against enemy's missile interception while considering its impact angle, acceleration, and field-of-view constraints. The first component of the synthesis is a new function of repulsive Artificial Potential Field to generate the evasive maneuver as a real-time dynamic obstacle avoidance. The terminal impact angle and terminal acceleration constraints compliance are based on Time-to-Go Polynomial Guidance as the second component. The last component is the Logarithmic Barrier Function to satisfy the field-of-view limitation constraint by compensating the excessive total acceleration command. These three components are synthesized into a new guidance law, which involves three design parameter gains. Parameter study and numerical simulations are delivered to demonstrate the performance of the proposed repulsive function and guidance law. Finally, the guidance law simulations effectively achieve the zero terminal miss distance, while satisfying an evasive maneuver against intercept missile, considering impact angle, acceleration, and field-of-view limitation constraints simultaneously.

• 대한임베디드공학회논문지
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• 제7권5호
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• pp.227-239
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• 2012

Recent advances in electronics have enabled various conventional products to incorporate with numerous powerful microcontroller. Generally, an embedded system is a computer system designed for specific control functions within a larger system, often with real-time computing constraints. The growing performance and reliability of hardware components and the possibilities brought by various design method enabled implementing complex functions that improve the comport of the system's occupant as well as their safety. A cyber physical system (CPS) is a system featuring a tight combination of, and coordination between, the system's computational and physical elements. The concept of cyber physical system, including physical elements, cyber elements, and shared networks, has been introduced due to two general reasons: design flexibility and reliability. This paper presents a cyber physical system where system components are connected to a shared network, and control functions are divided into small tasks that are distributed over a number of embedded controllers with limited computing capacity. In order to demonstrate the effectiveness of cyber physical system, an unmanned forklift with autonomous obstacle avoidance ability is implemented and its performance is experimentally evaluated.

• 유통과학연구
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• 제13권6호
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• pp.11-15
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• 2015

Purpose - Robot path planning, a constrained optimization problem, has been an active research area with many methods developed to tackle it. This study proposes the use of a Rapidly-exploring Random Tree and Particle Swarm Optimizer algorithm for path planning. Research design, data, and methodology - The grid method is built to describe the working space of the mobile robot, then the Rapidly-exploring Random Tree algorithm is applied to obtain the global navigation path and the Particle Swarm Optimizer algorithm is adopted to obtain the best path. Results - Computer experiment results demonstrate that this novel algorithm can rapidly plan an optimal path in a cluttered environment. Successful obstacle avoidance is achieved, the model is robust, and performs reliably. The effectiveness and efficiency of the proposed algorithm is demonstrated through simulation studies. Conclusions - The findings could provide insights to the validity and practicability of the method. This method makes it is easy to build a model and meet real-time demand for mobile robot navigation with a simple algorithm, which results in a certain practical value for distribution environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.270-286
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• 2012

In this paper, we propose a novel routing protocol called the Cartography Enhanced OLSR (CE-OLSR) for multi hop mobile ad hoc networks (multi hop MANETs). CE-OLSR is based on an efficient cartography gathering scheme and a stability routing approach. The cartography gathering scheme is non intrusive and uses the exact OLSR reduced signaling traffic, but in a more elegant and efficient way to improve responsiveness to the network dynamics. This cartography is a much richer and accurate view than the mere network topology gathered and used by OLSR. The stability routing approach uses a reduced view of the collected cartography that only includes links not exceeding a certain distance threshold and do not cross obstacles. In urban environments, IEEE 802.11 radio signals undergo severe radio shadowing and fading effects and may be completely obstructed by obstacles such as buildings. Extensive simulations are conducted to study the performances of CE-OLSR and compare them with those of OLSR. We show that CE-OLSR greatly outperforms OLSR in delivering a high percentage of route validity, a much higher throughput and a much lower average delay. In particular the extremely low average delay exacerbated by CE-OLSR makes it a viable candidate for the transport of real time data traffic in multi hop MANETs.

• 한국통신학회논문지
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• 제19권8호
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• pp.1503-1517
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• 1994

형상의 제한이 없는 장애물들로 구성된 미지의 2차원 환경에서 주어진 목표점을 향하는 로보트의 효율적인 경로를 생성하기 위한 지능적인 경로를 생성하기 위한 지능적 운동 계획 시스템을 제안하였다. 지능적 운동 계획 시스템은 지능적인 운동을 만들어 내기 위한 세 가지의 성분으로 이루어져 있으며, 불연속 경계 방식에 기초한 실시간 경로계획 알고리즘과, 경험적인 지식을 표현하기 위한 퍼지 신경회로망 판단 시스템, 그리고 기억의 손실과 보장 기능이 있는 외부 지도 생성 기술로 나뉘어진다. 먼저 실시한 경로 계획 알고리즘 부분에서는 중간 목표점을 생성하기 위한 행동 기준 구성 방식을 이용한다. 각 행동약식은 새롭게 제안된 실시간 충돌회피 얄고리즘인 불연속경계 방식을 이용하여 독립적으로 중간 목표점을 생성할 수 있다. 중간 목표점을 수행하기 위하여 퍼지 신경회로망 판단 시스템을 이용하였으며 지능적인 판단을 위한 경험적인 규칙들은 퍼지 신경회로망 내에 삽입되어 있다. 마지막 부분은 외부 환경 지도를 생성하기 위한 기억의 손실과 보강기능이 있는 기억 기술로서, 격자 공간 내에서 활성된 모든 기억 소자들의 활성 값은 점진적으로 감소하며 결국에는 모든 기억이 사라진다. 그러나 기억 소자가 재활성 되었을 때는 퍼지 규칙을 이용하여 더욱 길어진 활성 시간을 갖게 되므로 충분한 이동 후에는 동적인 장애물들이 존재하여도 고정적인 외부 환경 지도를 생성한다. 다양한 예제를 통하여 제안된 지능적 운동 계획 시스템이 여러 형태의 장애물들로 구성된 미지의 환경속에서 주어진 목표점에 효율적으로 도달할 수 있음을 보였다.

• 한국지능시스템학회논문지
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• 제21권2호
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• pp.268-275
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• 2011

본 논문에서는 uDEAS(Univariate Dynamic Encoding Algorithm for Searches)를 이용하여 두 가지의 이동 로봇 최적 전역 경로 계획을 제안한다. 이동 로봇의 자율 주행을 위해서는 빠른 시간 내에 작업 공간에서의 최적 경로를 생성해야 한다. 따라서 본 논문에서는 이동 로봇의 실시간 최적 경로 계획을 위해 전역 경로 계획을 도입하여 장애물 지역과 비장애물 지역을 확인하고, 지도상의 노드점과 노트점을 이용하여 출발 지점과 도착 지점 사이의 기본 경로를 생성한다. 그리고 기본 경로를 사용하여 두 가지의 방법으로 경로를 생성하게 된다. 첫 번째 방법은 기본 경로에서 세 개의 노드점을 이용하여 대각선 경로를 생성하는 방법이다. 두 번째는 혼합 다항식의 파라미터를 uDEAS를 이용하여 탐색하고, 곡선 궤적을 생성하는 방법이다. 시뮬레이션을 통해 두개의 방법에 대해 비교 분석하였다.

• 제어로봇시스템학회논문지
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• 제18권10호
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• pp.970-976
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• 2012

In this paper, a single LRF has been used to produce a 3D map for the mobile robot navigation. The 2D laser scanners are used for mobile robots navigation, where the laser scanner is applied to detect a certain level of area by the straight beam. Therefore it is limited to the usages of 2D obstacle detection and avoidance. In this research, it is designed to complement a mobile robot system to move up and down a single LRF along the yaw axis. During the up and down motion, the 2D data are stacked and manipulated to build a 3D map. Often a single LRF data are mixed with Gaussian and impulse noises. The impulse noises are removed out by the hybrid median filter designed in this research. The 2D data which are improved by deleting the impulse noises are layered to build the 3D map. Removing impulse noises while preserving the boundary is a main advantages of the hybrid median filter which has been used widely to improve the quality of images. The effectiveness of this hybrid median filter for rejecting the impulse noises has been verified through the real experiments. The performance of the hybrid median filter is evaluated in terms of PSNR (Peak Signal to Noise Ratio) and the processing time.

• 한국인터넷방송통신학회논문지
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• 제24권3호
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• pp.77-85
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• 2024

본 논문에서는 열화상 카메라, 스피드돔 카메라, PTZ 카메라, 레이더, 라이다 센서와 스마트폰을 통합한 순찰 로봇을 설계하고 구현하였다. 이 로봇은 복잡한 환경에서도 효율적으로 감시하고 대응할 수 있는 능력을 갖추고 있으며, 특히 야간이나 가시성이 낮은 조건에서도 높은 성능을 발휘할 수 있도록 설계되었다. 로봇의 이동성을 위해 궤도 이동체계를 선택하였고, 실시간 데이터 처리와 의사결정을 위해 스마트폰 기반의 제어 시스템을 개발하였다. 다양한 센서의 조합은 로봇이 환경을 포괄적으로 인식하고 위험 요소를 신속하게 감지할 수 있게 해준다. 열화상 카메라는 야간 감시에, 스피드돔과 PTZ 카메라는 광범위한 영역 모니터링에, 레이더와 라이다는 장애물 탐지와 회피에 활용된다. 스마트폰 기반 제어 시스템은 사용자 친화적인 인터페이스를 제공한다. 제안된 로봇 시스템은 보안, 감시, 재난 대응 등 다양한 분야에서 활용 가능하다. 향후 연구에서는 로봇의 자율 순찰 알고리즘 개선, 다중 로봇 협업 시스템 개발, 실제 환경에서의 장기 테스트 등이 수행되어야 할 것이다. 본 연구는 지능형 감시 로봇 분야의 발전에 기여할 것으로 기대된다.