• Title/Summary/Keyword: Local Minimum

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Bus Reconfiguration Strategy Based on Local Minimum Tree Search for the Event Processing of Automated Distribution Substation (자동화된 변전소의 이벤트 발생시 준최적 탐색법에 기반한 모선 재구성 전략의 개발)

  • Ko Yun-Seok
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.53 no.10
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    • pp.565-572
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    • 2004
  • This paper proposes an expert system which can enhance the accuracy of real-time bus reconfiguration strategy by adopting local minimum tree search method and minimize the spreading effect of the fault by considering totally the operating condition when a main transformer fault occurs in the automated substation. The local minimum tree search method to expand the best-first search method. This method has an advantage which can improve the performance of solution within the limits of the real-time condition. The inference strategy proposed expert system consists of two stages. The first stage determines the switching candidate set by searching possible switching candidates starting from the main transformer or busbar related to the event. And, second stage determines the rational real-time bus reconfiguration strategy based on heuristic rules for the obtained switching candidate set. Also, this paper studies the generalized distribution substation modelling using graph theory and a substation database is designed based on the study result. The inference engine of the expert system and the substation database is implemented in MFC function of Visual C++. Finally, the performance and effectiveness of the proposed expert system is verified by comparing the best-first search solution and local minimum tree search solution based on diversity event simulations for typical distribution substation.

Bus Reconfiguration Strategy Based on Local Minimum Tree Search for the Event Processing of Automated Distribution Substations

  • Ko Yun-Seok
    • KIEE International Transactions on Power Engineering
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    • v.5A no.2
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    • pp.177-185
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    • 2005
  • This paper proposes an expert system that can enhance the accuracy of real-time bus reconfiguration strategy by adopting the local minimum tree search method and that can minimize the spreading effect of the fault by considering the operating condition when a main transformer fault occurs in an automated substation. The local minimum tree search method is used to expand the best-first search method. This method has the advantage that it can improve the solution performance within the limits of the real-time condition. The inference strategy proposed expert system consists of two stages. The first stage determines the switching candidate set by searching possible switching candidates starting from the main transformer or busbar related to the event. The second stage determines the rational real-time bus reconfiguration strategy based on heuristic rules from the obtained switching candidate set. Also, this paper proposes generalized distribution substation modeling using graph theory, and a substation database based on the study results is designed.

A trajectory plannings avoiding structural local minimum problem in robot path planning using potential field (전위장을 이용한 로봇 경로계획의 구조적 Local minimum을 극복하는 경로계획 방법)

  • Nam, Heon-Seong;Lee, Ji-Hong;Lyou, Joon
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.33B no.9
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    • pp.13-23
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    • 1996
  • When artificial potential field approach is used to avoid obstacle, the problem can be occurred in case that manipulator selects the path which across over an obstacle among paths. In thiscase manipulator can't reach the desired goal form obstacle. This problem is a case of structual local minimum. so this paper proposes the method to solve structual local minimum in this case. The method is that the manipulator goes via temporary goal. This paper proposes that visual region concept to select the temporary goal. The temporary goal is selected on the border of the visual region. To prove its effectiveness, two simulation examples are done by two link manipulator in two dimension and by three link manipulator in three dimension.

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A New Technique to Escape Local Minimum in Artificial Potential Field Based Path Planning

  • Park, Min-Gyu;Lee, Min-Cheol
    • Journal of Mechanical Science and Technology
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    • v.17 no.12
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    • pp.1876-1885
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    • 2003
  • The artificial potential field (APF) methods provide simple and efficient motion planners for practical purposes. However, these methods have a local minimum problem, which can trap an object before reaching its goal. The local minimum problem is sometimes inevitable when an object moves in unknown environments, because the object cannot predict local minima before it detects obstacles forming the local minima. The avoidance of local minima has been an active research topic in the potential field based path planing. In this study, we propose a new concept using a virtual obstacle to escape local minima that occur in local path planning. A virtual obstacle is located around local minima to repel an object from local minima. We also propose the discrete modeling method for the modeling of arbitrary shaped objects used in this approach. This modeling method is adaptable for real-time path planning because it is reliable and provides lower complexity.

Formation Algorithm with Local Minimum Escape for Unicycle Robots (유니사이클 로봇을 위한 지역최소점 탈출을 갖춘 포메이션 알고리즘)

  • Jung, Hahmin;Kim, Dong Hun
    • Journal of Institute of Control, Robotics and Systems
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    • v.19 no.4
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    • pp.349-356
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    • 2013
  • This paper presents formation control based on potential functions for unicycle robots. The unicycle robots move to formation position which is made from a reference point and neighboring robots. In the framework, a local minimum case occurred by combination of potential repulsed from neighboring robots and potential attracted from a formation line is presented, in which the robot escapes from a local minimum using a virtual escape point after recognizing trapped situation. As well, in the paper, potential functions are designed to keep the same distance between neighboring robots on a formation line, i.e. the relative distance between neighboring robots on a formation line is controlled by a potential function parameter. The simulation results show that the proposed approach can effectively construct straight line, V, and polygon formation for multiple robots.

Sensor-Based Motion Planning for Mobile Robots

  • Park, Jong-Suk;Lee, Chong-won
    • 제어로봇시스템학회:학술대회논문집
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    • 2002.10a
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    • pp.37.3-37
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    • 2002
  • $\textbullet$ Mobile robots $\textbullet$ Sensor-based motion planning $\textbullet$ Potential field $\textbullet$ Local minimum-free motion $\textbullet$ Virtual target point $\textbullet$ Set of linked line segments $\textbullet$ We build a sensor-based motion planning using virtual target point for free of local minimum

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Global Optimization Using a Sequential Algorithm with Orthogonal Arrays in Discrete Space (이산공간에서 순차적 알고리듬(SOA)을 이용한 전역최적화)

  • Cho, Bum-Sang;Lee, Jeong-Wook;Park, Gyung-Jin
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.858-863
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    • 2004
  • In the optimized design of an actual structure, the design variable should be selected among any certain values or corresponds to a discrete design variable that needs to handle the size of a pre-formatted part. Various algorithms have been developed for discrete design. As recently reported, the sequential algorithm with orthogonal arrays(SOA), which is a local minimum search algorithm in discrete space, has excellent local minimum search ability. It reduces the number of function evaluation using orthogonal arrays. However it only finds a local minimum and the final solution depends on the initial value. In this research, the genetic algorithm, which defines an initial population with the potential solution in a global space, is adopted in SOA. The new algorithm, sequential algorithm with orthogonal arrays and genetic algorithm(SOAGA), can find a global solution with the properties of genetic algorithm and the solution is found rapidly with the characteristics of SOA.

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Mobile Robot Navigation For Recovering Local Minimum Using Ultrasonic Sensor (초음파센서를 이용한 이동 로봇의 지역 최소 회복을 위한 주행 알고리즘)

  • Myung, Ki-Ho;Yang, Dong-Hoon;Yoo, Young-Dong;Hong, Suk-Kyo
    • Proceedings of the KIEE Conference
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    • 1999.07g
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    • pp.3086-3088
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    • 1999
  • An ultrasonic sensor is one of most popular sensor used to navigate mobile robots within environments containing obstacles. But many navigation algorithm have studied because of the drawback of ultrasonic sensor such that poor directionality, frequent misreadings, specular reflections. Also, the most crucial drawback of this algorithm, that is VFF, VFM, EDM, PFM, WFM, GFM etc. has been that the mobile robot may become trapped in a local minimum. In this paper, we present a theoretical study of a navigation algorithm which integrals a heuristic-search local minimum (or trap) recovery method with a vector-field based method to maneuver cylindric mobile robots in unknown of unstructured environments. Also, an autonomous mobile robot uses dead-reckoning to estimate the current position and orientation of a mobile robot.

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Rank-based PSO Using Clustering (순위-기반 클러스터링 이용한 PSO)

  • Kang, Shinho;Lim, Dong-Hyun;Ahn, Chan-Wook
    • Proceedings of the Korea Information Processing Society Conference
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    • 2009.11a
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    • pp.295-296
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    • 2009
  • 본 논문은 기존 PSO의 문제점으로 지적되는 Local minimum에의 고착을 해결하여 평균적인 성능을 향상시킬 수 있는 방법을 제안한다. 이를 위해 기존에는 하나의 Best Value만을 향해서 이동하는 것에서 벗어나, 각 Particle들을 Cluster로 나누고 각각의 Best Value를 중심으로 이동하며, 각 Cluster Leader들은 다른 Cluster Leader와 통신하며 순위에 따라 이동한다. 제안 방법으로 수렴속도와 Local minimum 회피에 대해 실험을 통해 비교 분석한다. 실험 결과로부터 제안 방법이 Local minimum 회피에서 성능 향상이 있음을 고찰하였다.

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