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A Study on the N-Path SC Tracking Filter using PLL (PLL을 이용한 N-Path SC추적여파기에 관한 연구)

  • Jung, Sung-Hwan;Son, Hyun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.8 no.3
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    • pp.83-90
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    • 1983
  • N-path SC tracking filter is studied beyond the audio frequency range. First, the SC filter Cell which would determine total SC filter characteristics is analyzed by the two methods, charge equation method and difference equation method. Second, 4-path and 8-path SC filter are presented, including only capacitors and switches. Then, 4-path and 8-path SC tracking filter are constructed by conisting of SC filter block and PLL block. In this experiment, maximum response shift is confirmed. With respect to the capacitor ratios and the number of path, Q and Gain(dB) is considered. Also tracking range is measured.

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Redundancy Path Routing Considering Associativity in Ad Hoc Networks (Ad Hoc Network에서 Associativity을 고려한 Redundancy 경로 라우팅)

  • 이학후;안순신
    • Proceedings of the Korean Information Science Society Conference
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    • pp.199-201
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    • 2003
  • Ad hoc network은 stationary infrastructure의 도움 없이 이동 노드들이 필요 시 network 형태을 구성하여 통신이 이루어지게 하는 network으로 ad hoc network 환경에 맞는 다양한 라우팅 프로토콜들이 개발되었고 크게는 table­driven, on­demand 방식으로 나눌 수 있는데 on­demand 방식의 AODV 프로토콜은 routing overhead가 적다는 장점이 있는 반면 single path로 data forwarding을 진행하여 중간노드의 이동에 의한 path가 broken되는 경우 local routing을 하거나 새로이 source­initialed route rediscovery을 수행하여 전송 delay 및 control traffic overhead 등을 높이는 결과를 발생 시켰다. 본 논문은 single path로 구성되는 AODV 프로토콜의 route failures시 문제점을 보완한 Associativity Based Redundancy path Routing(ABRR) 및 Alternate Redundancy path Routing(ARR) schemes을 제안한다. 첫째, ABRR은 main path상에 있는 각 노드들은 associativity based stable node 정보를 이용하여 path broken 이전에 local redundancy path을 구성하여 path broken시 local routing없이 route을 복구할 수 있게 하고 둘째, ARR은 source­initialed route discovery에 의해 alternate path을 구성하여 ABRR 그리고 local routing에 의해 main route recovery 실패 시 alternate path을 main path로 전환하여 control traffic overhead 및 전송 delay을 줄이게 한다.

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Real-time Hybrid Path Planning Algorithm for Mobile Robot (이동로봇을 위한 실시간 하이브리드 경로계획 알고리즘)

  • Lee, Donghun;Kim, Dongsik;Yi, Jong-Ho;Kim, Dong W.
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.63 no.1
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    • pp.115-122
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    • 2014
  • Mobile robot has been studied for long time due to its simple structure and easy modeling. Regarding path planning of the mobile robot, we suggest real-time hybrid path planning algorithm which is the combination of optimal path planning and real-time path planning in this paper. Real-time hybrid path planning algorithm modifies, finds best route, and saves calculating time. It firstly plan the route with real-time path planning then robot starts to move according to the planned route. While robot is moving, update the route as the best outcome which found by optimal path planning algorithm. Verifying the performance of the proposed method through the comparing real-time hybrid path planning with optimal path planning will be done.

NURBS Post-processing of Linear Tool Path (미소직선 공구경로의 NURBS 변환)

  • Kim, Su-Jin;Choi, In-Hugh;Yang, Min-Yang
    • Proceedings of the KSME Conference
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    • pp.1111-1117
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    • 2003
  • NURBS (Non Uniform Rational B-Spline) is widely used in CAD system and NC data for high speed machining. Conventional CAM system changes NURBS surface to tessellated meshes or Z-map model, and produces linear tool path. The linear tool path is not good for precise machining and high speed machining. In this paper, an algorithm to change linear tool path to NURBS one was studied, and the machining result of NURBS tool path was compared with that of linear tool path. The N-post, post-processing and virtual machining software was developed. The N-Post post-processes linear tool path to NURBS tool path and quickly shades machined product on OpenGL view and compares a machined product with original CAD surface. A virtual machined model of original tool path and post-processed tool path was compared to original CAD model. The machining error of post-processed NURBS tool path was reduced to 43%. The original tool path and NURBS tool path was used to machine general model using same machine tool and machining condition. The machining time of post-processed NURBS tool path was reduced up to 38%.

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Temporal Waypoint Revision Method to Solve Path Mismatch Problem of Hierarchical Integrated Path Planning for Mobile Vehicle (이동 차량의 계층적 통합 경로 계획의 경로 부조화 문제 해결을 위한 임시 경유점 수정법)

  • Lee, Joon-Woo;Seok, Joon-Hong;Ha, Jung-Su;Lee, Ju-Jang;Lee, Ho-Joo
    • Journal of Institute of Control, Robotics and Systems
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    • v.18 no.7
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    • pp.664-668
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    • 2012
  • Hierarchical IPP (Integrated Path Planning) combining the GPP (Global Path Planner) and the LPP (Local Path Planner) is interesting the researches who study about the mobile vehicle in recent years. However, in this study, there is the path mismatch problem caused by the difference in the map information available to both path planners. If ever a part of the path that was found by the GPP is available to mobile vehicle, the part may be unavailable when the mobile vehicle generates the local path with its built-in sensors while the vehicle moves. This paper proposed the TWR (Temporal Waypoint Reviser) to solve the path mismatch problem of the hierarchical IPP. The results of simulation provide the performance of the IPP with the TWR by comparing with other path planners.

Application of Quadratic Algebraic Curve for 2D Collision-Free Path Planning and Path Space Construction

  • Namgung, Ihn
    • International Journal of Control, Automation, and Systems
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    • v.2 no.1
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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.

The Study of Algorithm for the Path generation in the Obstacles Environment (장애물 환경에서 경로 생성을 위한 알고리즘 연구)

  • 황하성;양승윤;이만형
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.430-433
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    • 1996
  • In This paper, we design the developed path generation method which is named that CBPM(Continuous path generation method Based artificial Potential field) that is able to be used in the obstacles environment. This CBPM is designed so that it puts together two obstacle avoidance algorithm-the continuous path generation method and the artificial potential field method. Here, the continuous path generation method generate the safety path using continuous path curvature. But, this method has demerits when used in obstacles environment in which are closely located. Another method which is named the artificial potential field method generates the path with the artificial potential field in the obstacles environment. But, APFM has local minima in certain places and unnecessarily calculates the path in which obstacles are not located. So, the developed path generation method, CBPM, is suggested and performances in many different obstacles environments are shown by using computer simulation.

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G2 Continuity Smooth Path Planning using Cubic Polynomial Interpolation with Membership Function

  • Chang, Seong-Ryong;Huh, Uk-Youl
    • Journal of Electrical Engineering and Technology
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    • v.10 no.2
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    • pp.676-687
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    • 2015
  • Path planning algorithms are used to allow mobile robots to avoid obstacles and find ways from a start point to a target point. The general path planning algorithm focused on constructing of collision free path. However, a high continuous path can make smooth and efficiently movements. To improve the continuity of the path, the searched waypoints are connected by the proposed polynomial interpolation. The existing polynomial interpolation methods connect two points. In this paper, point groups are created with three points. The point groups have each polynomial. Polynomials are made by matching the differential values and simple matrix calculation. Membership functions are used to distribute the weight of each polynomial at overlapped sections. As a result, the path has $G^2$ continuity. In addition, the proposed method can analyze path numerically to obtain curvature and heading angle. Moreover, it does not require complex calculation and databases to save the created path.

Determination of Cutting Direction for Tool Path Minimization in Zigzag Milling Operation (Zigzag 밀링가공에서 공구경로 최소화를 위한 가공방향 결정방법)

  • Kim, Byoung-Keuk;Park, Joon-Young
    • Journal of Korean Institute of Industrial Engineers
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    • v.27 no.1
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    • pp.69-88
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    • 2001
  • In the zigzag milling operation, an important issue is to design a machining strategy which minimizes the cutting time. An important variable for minimization of cutting time is the tool path length. The tool path is divided into cutting path and non-cutting path. Cutting path can be subdivided into tool path segment and step-over, and non-cutting path can be regarded as the tool retraction. We propose a new method to determine the cutting direction which minimizes the length of tool path in a convex or concave polygonal shape including islands. For the minimization of tool path length, we consider two factors such as step-over and tool retraction. Step-over is defined as the tool path length which is parallel to the boundary edges for machining area and the tool retraction is a non-cutting path for machining any remaining regions. In the determination of cutting direction, we propose a mathematical model and an algorithm which minimizes tool retraction length in complex shapes. With the proposed methods, we can generate a tool path for the minimization of cutting time in a convex or concave polygonal shapes including islands.

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Path-Following using Path-Observer for Wheeled Mobile Robots (경로 관측기를 이용한 차륜형 이동 로봇의 경로 추종)

  • Lim, Mee-Seub;Lim, Joon-Hong
    • The Transactions of the Korean Institute of Electrical Engineers A
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    • v.48 no.11
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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.

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