• 제목/요약/키워드: isotropy

검색결과 142건 처리시간 0.032초

Local and Global Isotropy Analysis of Caster Wheeled Omnidirectional Mobile Robot

  • Kim Sung-bok;Moon Byoung-kwon
    • 융합신호처리학회논문지
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    • 제7권1호
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    • pp.38-44
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    • 2006
  • The omnidirectional mobility of a mobile robot may lose significance in motion control, unless the isotropy characteristics of the mechanism is maintained well. This paper investigates the local and global isotropy of an omnidirectional mobile robot with three caster wheels. All possible actuations with different number and combination of rotating and steering joints are considered. First, the kinematic model based on velocity decomposition and the algebraic conditions for the local isotropy are obtained. Second, the geometric conditions for the local isotropy are derived and all isotropic configurations are fully identified. Third, the global isotropy index is examined to determine the optimal parameters in terms of actuation set, characteristic length, and steering link length.

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Complete Identification of Isotropic Configurations of a Caster Wheeled Mobile Robot with Nonredundant/Redundant Actuation

  • Kim, Sung-Bok;Moon, Byung-Kwon
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2005년도 ICCAS
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    • pp.2356-2361
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    • 2005
  • In this paper, we present a complete isotropy analysis of a caster wheeled omnidirectional mobile robot(COMR) with nonredundant/redundant actuation. The motivation of this work is that the omnidirectional mobility loses significance in motion control unless the isotropy characteristics is maintained well. First, with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, a general form of the isotropy conditions of a COMR is given in terms of physically meaningful vector quantities which describe the wheel configurations. Third, for all possible nonredundant and redundant actuation sets, the algebraic expressions of the isotropy conditions are derived to completely identify the isotropic configurations of a COMR. Fourth, the number of the isotropic configurations and the characteristic length required for the isotropy are discussed.

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가변 조향링크 옵셋을 갖는 캐스터 바퀴 이동로봇의 등방성 분석 (Isotropy Analysis of Caster Wheeled Mobile Robot with Variable Steering Link Offset)

  • 김성복;문병권
    • 제어로봇시스템학회논문지
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    • 제12권12호
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    • pp.1235-1240
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    • 2006
  • Previous isotropy analysis of a caster wheeled omnidirectional mobile robot(COMR) has been made under the assumption that the steering link offset is equal to the caster wheel radius. Nevertheless, many practical COMR's in use take advantage of the steering link offset different from the wheel radius, mainly because of improved stability. This paper presents the isotropy analysis of a fully actuated COMR with variable steering link offset, which can be considered as the generalization of the previous analysis. First, the kinematic model of a COMR under full actuation is obtained based on the orthogonal decomposition of the wheel velocities. Second, the necessary and sufficient conditions for the isotropy of a COMR are derived and examined to categorize three different groups, each of which can be dealt with in a similar way. Third, for each group, the isotropy conditions are further explored so as to identify all possible isotropic configurations completely.

Systematic Isotropy Analysis of Caster Wheeled Mobile Robot with Steering Link Offset Different from Wheel Radius

  • 김성복
    • 융합신호처리학회논문지
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    • 제7권4호
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    • pp.214-220
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    • 2006
  • This paper presents the systematic isotropy analysis of a fully actuated caster wheeled omnidirectional mobile robot (COMR) with the steering link offset different from the wheel radius, which can be considered as the generalization of the previous analysis. First with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, the necessary and sufficient conditions for the isotropy of a COMR are derived and examined to categorize there different groups, each of which can be dealt with in a similar way. Third, for each group, the isotropy conditions are further explored so as to identify four different sets of all possible isotropic configurations. Fourth, for each set the expressions of the isotropic characteristic length required for the isotropy of a COMR are elaborated.

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Complete Identification of Isotropic Configurations of a Caster Wheeled Mobile Robot with Nonredundant/Redundant Actuation

  • Kim Sung-Bok;Moon Byung-Kwon
    • International Journal of Control, Automation, and Systems
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    • 제4권4호
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    • pp.486-494
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    • 2006
  • In this paper, we present the complete isotropy analysis of a caster wheeled omnidirectional mobile robot (COMR) with nonredundant/redundant actuation. It is desirable for robust motion control to keep a COMR close to the isotropy but away from the singularity as much as possible. First, with the characteristic length introduced, the kinematic model of a COMR is obtained based on the orthogonal decomposition of the wheel velocities. Second, a general form of the isotropy conditions of a COMR is given in terms of physically meaningful vector quantities which specify the wheel configuration. Third, for all possible nonredundant and redundant actuation sets, the algebraic expressions of the isotropy conditions are derived so as to identify the isotropic configurations of a COMR. Fourth, the number of the isotropic configurations, the isotropic characteristic length, and the optimal initial configuration are discussed.

정수압하에서 박판 정방벌지의 변형특성과 불안정에 관한 연구 (A study on the characteristic and instability of the diaphram square bulge under hydraulic pressure)

  • 강대민
    • 한국안전학회지
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    • 제12권3호
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    • pp.52-59
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    • 1997
  • Hill's anisotropy theory and isotropy theory under the deformed profile assumed two separate cases(that is circular and ellipitical) are applied to predict the plastic deformation characteristics of bulge, the strain and polar height under instability condition, using thin square diaphragms of stainless steel, mild steel, brass, copper and aluminum. In this study it was found that the pressure-polar height curves, and the polar height-the polar radius of curvature curve, under anisotropy theory and isotropy theory, assuming a circle profile, agree well with the experimental results, and the equivalent strains of the instability condition under anisotropy theory are better good agreement with the experimental results than those of the instability condition under isotropy theory. Beside, FLCo(plane Strain Intercept) obtained by Bethlehem FLC method and standard FLC method (modified) agree well with the experimental result.

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기구학적 등방성을 고려한 특정작업경로를 가진 6-DOF 병렬형 매니퓰레이터 (The 6-DOF Parallel Manipulator Having the Specific Trajectory Based on the Kinematic Isotropy)

  • 양현익;허원혁
    • 대한기계학회논문집A
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    • 제28권5호
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    • pp.495-502
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    • 2004
  • In this paper, kinematic structure of parallel manipulator having 6-DOF is determined to follow the specific trajectory represented by several curves expressed by the parametric variable functions. In addition, the parallel manipulator is designed to have a high dexterity by considering a kinematic isotropy which can stabilize the motion of the moving platform in the restricted workspace.

CLASSIFICATION OF EQUIVARIANT VECTOR BUNDLES OVER REAL PROJECTIVE PLANE

  • Kim, Min Kyu
    • 충청수학회지
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    • 제24권2호
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    • pp.319-335
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    • 2011
  • We classify equivariant topoligical complex vector bundles over real projective plane under a compact Lie group (not necessarily effective) action. It is shown that nonequivariant Chern classes and isotropy representations at (at most) three points are sufficient to classify equivariant vector bundles over real projective plane except one case. To do it, we relate the problem to classification on two-sphere through the covering map because equivariant vector bundles over two-sphere have been already classified.

공간자료의 기하학적 비등방성 연구 (On the Geometric Anisotropy Inherent In Spatial Data)

  • 고혜지;박만식
    • 응용통계연구
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    • 제27권5호
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    • pp.755-771
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    • 2014
  • 등방성(isotropy)은 공분산 모형(covariance model)에 기반으로 공간 예측(spatial prediction)이라 불리우는 크리깅(kriging) 을 용이하게 수행하기 위한 주요 가정 중의 하나로 알려져있다. 공간 과정에서 등방성이 충족되지 않는 경우에는, 보다 신뢰성 예측을 생성하기 위해 비등방성 공분산 모형(covariance model)과 관련된 모수들(각도 및 비율)를 추정해야 한다. 본 논문에서는 여러 방향의 기하학적 비등방성 모형(geometrically anisotropic covariance models)의 가중 평균으로 표현되는 확장된 형태의 기하학적 비등방성(geometrically extended anisotropic) 공분산모형을 제안한다. 연구에 관심이 되는 모수를 추정하기 위해 최대우도추정법(maximum likelihood estimation method)을 이용하였다. 제안한 모형의 성능을 평가하기 위해 등방성 공분산모형과 기하학적 비등방성 모형을 고려한 모의실험을 수행하였다. 또한 확장된 기하학적 비등방성 모형을 적용한 미세먼지 농도자료 분석을 실시하였다.

2차모멘트 난류모형을 이용한 정사각 단면 곡덕트 내 발달하는 난류유동 변화에 대한 고찰 (Investigation on the Developing Turbulent Flow In a Curved Duct of Square Cross-Section Using a Low Reynolds Number Second Moment Turbulence Closure)

  • 전건호;최영돈;신종근
    • 대한기계학회논문집B
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    • 제23권8호
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    • pp.1063-1071
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    • 1999
  • Fine grid calculations are reported for the developing turbulent flow in a curved duct of square cross-section with a radius of curvature to hydraulic diameter ratio ${\delta}=Rc/D_H=3.357 $ and a bend angle of 720 deg. A sequence of modeling refinements is introduced; the replacement of wall function by a fine mesh across the sublayer and a low Reynolds number algebraic second moment closure up to the near wall sublayer in which the non-linear return to isotropy model and the cubic-quasi-isotropy model for the pressure strain are adopted; and the introduction of a multiple source model for the exact dissipation rate equation. Each refinement is shown to lead to an appreciable improvement in the agreement between measurement and computation.