• 대한전기학회논문지:시스템및제어부문D
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• 제50권3호
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• pp.143-148
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• 2001

A lot of robot trajectory tracking methods are proposed to enhance the tracking error, but irregular tracking errors are always accompanied and very hard to reduce it. Up to now, these irregular tracking errors are reduced by introducing more complicated control algorithms. But, it is intuitively obvious to reduce only the big errors selectively in the irregular ones for the better performance instead of using more complicated control algorithms. By the characteristics of the robot, big tracking errors of the end-effector are generated mostly due to the fast moving of joint. So, in this paper, we introduce a new method which reduce the big tracking errors by clippings the joint velocity with the constraint of given path. Using this method, desired trajectory tracking is obtained within the far reduced error bound. Also, this method is successfully applied to generate the path-constrained error reducing trajectories for 2-axis SCARA type robot.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1496-1499
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• 2004

In this paper, we deal with a novel path planning algorithm to find collision-free path for a moving robot to find an appropriate path from initial position to goal position. The robot should make progress by avoiding obstacles located at unknown position. Such problem is called the path planning. We propose so called the subgoal generation algorithm to find an effective collision-free path. The generation and selection of the subgoal are the key point of this algorithm. Several subgoals, if necessary, are generated by analyzing the map information. The subgoal is the candidate for the final path to be pass through. Then selection algorithm is executed to choose appropriate subgoal to construct a correct path. Deep and through explanations are given for the proposed algorithm. Simulation example is given to show the effectiveness of the proposed algorithm.

• 한국전문물리치료학회지
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• 제12권4호
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• pp.12-19
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• 2005

The purpose of this study was to investigate the possibility of virtual moving surround (VMS) on static balance in the patients with balance dysfunction. Eighty three subjects who were admitted or treated as an outpatient, or a family member, at the department of rehabilitation unit of university hospital were recruited to participate. Subjects were three groups based on their overall medical status: healthy, diabetic neuropathy and stroke. Each group was tested for static balance with a forceplate during static standing with VMS. The virtual movement was simulated with a head mounted display. The parameters for static balance were total sway path. In this study, the parameters of postural control for patients with diabetic neuropathy and stroke subjects were significantly increased in conditions elicited with the VMS. In the healthy elderly participants, the total sway path was not significantly different under virtual movement conditions. Therefore, VMS could be used in the evaluation and treatment of the patients with balance dysfunction.

• International Journal of Control, Automation, and Systems
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• 제3권3호
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• pp.444-452
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• 2005

A new scheme for a mobile robot to track and capture a moving object using camera images is proposed. The moving object is assumed to be a point-object and is projected onto an image plane to form a geometrical constraint equation that provides the position data of the object based on the kinematics of the active camera. Uncertainties in position estimation caused by the point-object assumption are compensated for using the Kalman filter. To generate the shortest time path to capture the moving object, the linear and angular velocities are estimated and utilized. In this paper, the experimental results of the tracking and capturing of a target object with the mobile robot are presented.

• 융합신호처리학회논문지
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• 제3권3호
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• pp.6-13
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• 2002

본 논문에서는 신호 교차로에서 red-time 및 green-time의 backward moving 충격파 속도를 자동 측정하는 영상처리 기반 방법을 제안한다. 충격파(shockwave)란 서로 다른 교통류 상태가 만나는 불연속적인 경계선을 의미하며, 충격파 속도는 충격파가 움직이는 속도 즉, 경계선의 기울기로 구해진다. 본 논문에서는 충격파 속도를 자동 측정하기 위해 거리-시간 다이어그램(distance-time diagram)을 작성하였다. 차량의 전역 추적을 통해서 모든 개별 차량의 이동 경로를 거리-시간 다이어그램에 나타내었고, 이동 경로 곡선의 기울기 변화 패턴을 분석하여 red-time 및 green-time의 backward moving 충격파 속도를 계산하였다. 제안된 방법을 신호 교차로에서 실험하였고 red-time 및 green-time backward moving 충격파 속도의 측정 결과를 얻었다. 충격파 속도를 측정하게 되면 차량 진행 방향의 교통 혼잡 상황을 쉽게 파악할 수 있으므로 고속 도로의 진입차선 제어, 교차로의 자동 신호제어에 효과적으로 응용할 수 있다.

• 제어로봇시스템학회논문지
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• 제15권1호
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• pp.105-110
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• 2009

In this paper, we proposed a navigation algorithm of the mobile robot for obstacle avoidance using a circular path planning method. The proposed method makes circular paths in order to avoid obstacles in the front side of the mobile robot. An optimal path for approaching to the target is selected and the linear and angular speeds for stable moving of the mobile robot are controlled. Obstacles are detected by image processing which reduce image data obtained from a web camera. Performance of the proposed algorithm is shown by experiments with application to the Pioneer-2DX mobile robot.

• 제어로봇시스템학회논문지
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• 제17권5호
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• pp.405-411
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• 2011

This paper presents a hierarchical trajectory planning method which can handle a collision-free of the planned path in complex and dynamic environments. A PV (Path & Velocity profile) planning method minimizes a sharp change of orientation and waiting time to avoid a collision with moving obstacle through detour path. The path generation problem is solved by three steps. In the first step, a smooth global path is generated using $A^*$ algorithm. The second step sets up the velocity profile for the optimization problem considering the maximum velocity and acceleration. In the third step, the velocity profile for obtaining the shortest path is optimized using the fuzzy and genetic algorithm. To show the validity and effectiveness of the proposed method, realistic simulations are performed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 B
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• pp.843-845
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• 1995

There are a variety of trajectory and control algorithms available for robot trajectory tracking. Before using the enhanced trajectory and control algorithms to reduce the tracking error, we introduce the new method which reduces the tracking error by clipping the joint velocity. A lot of robot trajectory tracking methods are proposed to enhance the robot tracking, but irregular tracking errors are always accompanied. Up to now, these irregular tracking errors are gradually but uniformly reduced by introducing more complicated control algorithms. It is intuitively obvious to reduce only the big errors selectively in the irregular ones for the better performance. By heuristic method, big tracking errors in these irregular ones are assumed mostly due to the fast moving of joint with respect to the same tracking and control method. So, in this paper, we introduce a new method which reduce the big tracking errors by clippings the joint velocity with the constraint of given path. Using this method, desired trajectory tracking is obtained within the far reduced error bound. Also, this method is successfully applied to generate the path-constrained error reducing trajectories for 2-axis SCARA type robot.

• 정보처리학회논문지:컴퓨터 및 통신 시스템
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• 제2권10호
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• pp.427-436
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• 2013

본 논문에서는 실내에서 비전센서를 이용한 마커 영상 인식을 통해 무인이송차량(AGV)의 주행 경로를 제어하는 방안을 제안한다. 적외선센서와 랜드마크를 이용한 AGV 주행 제어 시스템의 경우 실내로 투과되어 들어 온 햇빛으로 인해 적외선 센싱 결과를 제대로 인식하지 못하는 공간이 발생하는 점과 작업 공간이 협소할 경우 랜드마크를 이용한 주행 경로 제어가 어려운 상황이 발생하였다. 이처럼 WSN 환경에서 센싱정보를 획득하지 못하는 상황을 보완할 수 있는 방안으로 마커와 AGV 간 상대 거리 정보를 지문 정보로 활용하는 방안을 제안한다. 무선신호 수신세기(RSS)를 지문으로 사용하는 방식에 비해 마커 영상 이미지 크기를 지문으로 사용하면 상대적으로 신뢰도가 높은 위치 정보를 획득할 수 있다. 모형 AGV를 이용한 다양한 실험을 통해 상대 거리 정보를 지문으로 사용하는 방안의 타당성을 입증하였다. 본 논문의 연구 결과는 화장장에서 시신을 운구하는 무인이송차량 시스템에 적용될 것이다.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제19권3호
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• pp.235-252
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• 2015

Optimal impact angle control guidance law and its variants for intercepting a maneuvering target are introduced in this paper. The linear quadratic(LQ) optimal control theory is reviewed first to setup framework of guidance law derivation, called the sweep method. As an example, the inversely weighted time-to-go energy optimal control problem to obtain the optimal impact angle control guidance law for a fixed target is solved via the sweep method. Since this optimal guidance law is not applicable for a moving target due to the angle mismatch at the impact instant, the law is modified to three different biased proportional navigation(PN) laws: the flight path angle control law, the line-of-sight(LOS) angle control law, and the relative flight path angle control law. Effectiveness of the guidance laws are verified via numerical simulations.