• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 B
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• pp.627-629
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• 1999

The research fields of mobile robot consist of three parts. The first is path planning, the second is the application of new sensors, and the last is a combination of the communication technology and mobile robot. In this paper we treat the path-planning. We use a Bayesian probability map, Distance Transform and Fuzzy logic for a path-planning. DT and Fuzzy logic algorithms search for path in entire, continuous free space and unifies global path planning and local path planning. It is efficient and effective method when compared with navigators using traditional approaches.

• 전자공학회논문지S
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• 제34S권2호
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• pp.21-32
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• 1997

This paper proposes an elliptical world-modeling mehtrod in order to secure the safety of the mobile robot from the unreliability of ultrasonic sensors and to estimate the lateral orientation of the detected objects. This method is advnatageous because the total amount of data that the robot utilizes is reduced when historical and new data are clusterd during each sensing period and also because the objects in the environment can be almost exactly recognized. This paper also proposes a new local path planning algorithm which is divided into four different situations and gudies the robot through the safe local path using dat acollected in elliptical form. This algorithm can help the AMR navigate by allowing it to sum up the virtual vector forces made form the ellipses in order to select a safe subgoal. This local path plannin gmehtod using the elliptical world model has been proved by several navigation experiments.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2018년도 춘계학술대회
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• pp.415-418
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• 2018

기존 AODV의 플러딩 오버헤드를 줄이기 위하여 목적지에서 개시하는 지역적인 플러딩 방식을 제안한다. 제안 라우팅 프로토콜은 엿듣기 동작을 통하여 소스-목적지 최단 경로 주변의 1-홉 이웃 노드를 결정하고 토폴로지 변화에 대처하기 위하여 주기적으로 목적지에서 플러딩을 발생시킨다. 이 플러딩 과정은 최단 경로 주변의 1-홉 이웃 노드들만 참여시켜 플러딩 오버헤드를 줄이면서 최단 경로 주변에 다수의 대체 경로를 형성시킨다. 이를 통하여 사용 중인 전송 경로의 단절시 주변의 새로운 최단 경로로의 끊김 없는 라우팅이 가능하게 해준다.

• 전기전자학회논문지
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• 제13권2호
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• pp.150-158
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• 2009

로봇의 자율적 이동을 위해서는 현재지점에서부터 목표지점까지를 연결하는 최적 경로의 계획이 필수적이다. 그리고 이동 로봇의 최적 경로는 장애물과의 충돌 없이 목표물까지 최단 이동 거리로 이동 할 수 있도록 하는 경로를 뜻한다. 실제 많은 이동 로봇은 주위 장애물에 대한 정보 없이, 미지의 환경에서도 자율적 이동이 가능해야 한다. 이에, 본 논문에서는 미지 환경에 적합한 새로운 형태의 경로 계획 및 장애물 회피 방법을 제안한다. 이 경로 계획 방법은 매 순간 최적이라 예측되는 지역적 목표를 지정하여 추적하며, 이러한 추적의 연속들의 결과가 로봇의 1차적 이동 경로가 된다. 하지만 이 경로는 장애물과의 충돌이 배제된 경로이다. 이에, 본 논문에서는 Potential Field 방법을 모방한 새로운 방법의 장애물 회피 방법을 제안한다. 그리고 위의 본 논문에서 제안한 경로 계획과 장애물 회피 방법의 성능 및 정확성을 모의실험을 통해 검증한다.

• 대한전기학회논문지:전력기술부문A
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• 제48권11호
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• pp.1448-1456
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• 1999

In this paper, we propose a new technique for path-following of the wheeled mobile robot systems with nonholonomic constraints using a path-observer. We discuss the path-following problems of the nonholonomic mobile robot systems which have two nonsteerable, independently driven wheels with the various initial conditions such as a position, a heading angle, and a velocity. It is shown that the performance of dynamic path-following importantly is affected by the intial conditions. Particularly, if the initial conditions become more distant from the desired path and the desired velocity become faster, the system is shown to have worse performance and small time local stable. To find the controllable and stable control for path-following with various initial configuration, we propose the path-observer which can be used for control of the stable path-following of nonholonomic mobile robot system with the various initial conditions. The proposed scheme exhibits the efficient path-following properties for nonholonomic mobile robot in any intial conditions. The simulation results demonstrate the effectiveness of the proposed method for dynamic path-following tasks with the various initial conditions.

• 제어로봇시스템학회논문지
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• 제17권9호
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• pp.902-907
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• 2011

In this paper, we deal with performance evaluation of visual path following using 2D and 3D information. Visual path follow first teaches driving path by selecting milestone images then follows the same route by comparing the milestone image and current image. We follow the visual path following algorithm of [8] and [10]. In [8], a robot navigated with 2D image information only. But in [10], local 3D geometries are reconstructed between the milestone images in order to achieve fast feature prediction which allows the recovery from tracking failures. Experimental results including diverse indoor cases show performance of each algorithm.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.387-392
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• 1992

This paper presents a local trajectory generation method which is based on a sequence of reference posture-velocities and the efficient low level control algorithm which constructs the complete smooth curve from the trajectory specification. The reference trajectory generator(RTG) which is in between the local path planner(LPP) and the robot motion controller(RMC) generates a sequence of set-points for each path segments from the LPP and pass it to the RMC. The RMC controls the motions of vehicle which should follow the sequence. In the feedback controller of VMC, the method which compensates robot posture-velocity error correctly is used. These methods are implemented on indoor autonomous vehicle, 'ALIVE' mobile robot. The ALIVE mobile robot system is implemented on the 32bit VME bus system: the two VME CPU's are used for RTG and RMC, while the 80C196KC-based VME board is used for motor controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 D
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• pp.2401-2403
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• 2002

Given a certain target point, the mobile robot's navigation could be mainly considered about two areas, 'how fast and accurate' and 'how safe'. Such problems regarding the velocity and stability possess close relationship with the path in which the mobile robot navigates in. Thus, the system proposed in this research paper was constructed so the mobile robot can obtain the optimum path by utilizing the information according to the environmental map, based on the Global Path Planning. Also by inducing the Local Path Planning method, it was constructed so that the robots can avoid the obstacles, which were not shown in the environmental map on-line. Particularly, by fusing the Local and Global Path Planning together, it is possible for the robots to plan similar path. At the same time, the focus was on the materialization of effective mobile robot's navigation. It was made possible by utilizing the Fuzzy Logic Control. Also, the validity of the algorithm proposed was proven through the trial experiment.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1386-1391
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• 2004

It is known that an aircraft with delta-wings which are attached to the body at a large angle like a kite or a hang glider has a measure of maneuverability and stability. Aircrafts of this kind can fly stably. Even if engine trouble occurs, it will not fall and might be able to land. In this paper, one of the conventional control methods, PID control, is applied to the aircraft with LQ local control block. This is based on an idea that the aircraft flies so stably that the automatic control system might be realized by a simple controller. The proposed PID controller consists of several sub-controllers which are constructed to each system neglecting the interference. In addition, the LQ control is involved as a local loop of the aileron and rudder control in order to increase stability of the attitude when circling. The effectiveness of the proposed method is shown through 3D computer simulations and experiments of the flight path control.

• International Journal of Control, Automation, and Systems
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• 제2권1호
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• pp.107-117
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• 2004

A new algorithm for planning a collision-free path based on an algebraic curve as well as the concept of path space is developed. Robot path planning has so far been concerned with generating a single collision-free path connecting two specified points in a given robot workspace with appropriate constraints. In this paper, a novel concept of path space (PS) is introduced. A PS is a set of points that represent a connection between two points in Euclidean metric space. A geometry mapping (GM) for the systematic construction of path space is also developed. A GM based on the 2$^{nd}$ order base curve, specifically Bezier curve of order two is investigated for the construction of PS and for collision-free path planning. The Bezier curve of order two consists of three vertices that are the start, S, the goal, G, and the middle vertex. The middle vertex is used to control the shape of the curve, and the origin of the local coordinate (p, $\theta$) is set at the centre of S and G. The extreme locus of the base curve should cover the entire area of actual workspace (AWS). The area defined by the extreme locus of the path is defined as quadratic workspace (QWS). The interference of the path with obstacles creates images in the PS. The clear areas of the PS that are not mapped by obstacle images identify collision-free paths. Hence, the PS approach converts path planning in Euclidean space into a point selection problem in path space. This also makes it possible to impose additional constraints such as determining the shortest path or the safest path in the search of the collision-free path. The QWS GM algorithm is implemented on various computer systems. Simulations are carried out to measure performance of the algorithm and show the execution time in the range of 0.0008 ~ 0.0014 sec.