• 제목/요약/키워드: closed-form analysis

검색결과 687건 처리시간 0.022초

A STUDY ON THE RELATION BETWEEN CLOSED-FORM DESCRIPTION AND RECURSIVE-FORM REALIZATION OF ASAPTIVE CONTROL OF MANIPULATORS

  • Kubozono, Takeshi;Yamakita, Masaki;Furuta, Katsuhisa
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국제학술편); KOEX, Seoul; 22-24 Oct. 1991
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    • pp.1785-1789
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    • 1991
  • Recently, a number of papers on adaptive control scheme of manipulators are proposed. Slotine and Li[1] showed an adaptive control scheme for robot manipulator. The controller was described in closed form. And later Niemeyer and Slotine discussed about a computational implementation of the controller in recursive form[2]. Walker proposed another adaptive control scheme which can be implemented by a recursive-form controller[4]. Closed-form description is used for the analysis or design of adaptive control systems while recursive-form realization is used for implementation of the controller. The relation between the closed-form realization and the recursive-form one seems to be inadequately referred. Hence, it makes sense to consider the relation between the closed-form description and the recursive-form one. In this paper, first, we make a simple derivation of an closed-form dynamics description of a robot arm from its recursive-form description. And then we derive the closed-form realization of Walker's scheme applied to manipulators having no kinematic loop. We clarify the difference between the Walker's scheme and Slotine's and evaluate the convergence under the controllers.

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Analysis of Attenuation Poles using Closed-form Solutions for Bandpass Filters

  • Shin, Yoon-mi;Lee, Bom-Son
    • Journal of electromagnetic engineering and science
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    • 제1권2호
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    • pp.156-160
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    • 2001
  • Very convenient equivalent circuits fur the design of bandpass filters with an attenuation pole in the lower or upper stopband are provided together with necessary closed-form solutions. The proposed approach gives us much flexibility and simplifies the design of inserting attenuation poles.

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해석적인 기구학을 이용한 다물체계의 동력학해석 (Dynamics of multibody systems with analytical kinematics)

  • 이돈용;염영일;정완균
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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    • pp.289-292
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    • 1994
  • In this paper, the equations of motion are constructed systematically for multibody systems containing closed kinematic loops. For the displacement analysis of the closed loops, we introduce a new mixed coordinates by adding to the reference coordinates, relative coordinates corresponding to the degrees of freedom of the system. The mixed coordinates makes easy derive the explicit closed form solution. The explicit functional relationship expressed in closed form is of great advantages in system dimension reduction and no need of an iterative scheme for the displacement analysis. This forms of equation are built up in the general purpose computer program for the kinematic and dynamic analysis of multiboty systems.

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Can finite element and closed-form solutions for laterally loaded piles be identical?

  • Sawant, Vishwas A.;Shukla, Sanjay Kumar
    • Structural Engineering and Mechanics
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    • 제43권2호
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    • pp.239-251
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    • 2012
  • The analysis of laterally loaded piles is generally carried out by idealizing the soil mass as Winkler springs, which is a crude approximation; however this approach gives reasonable results for many practical applications. For more precise analysis, the three- dimensional finite element analysis (FEA) is one of the best alternatives. The FEA uses the modulus of elasticity $E_s$ of soil, which can be determined in the laboratory by conducting suitable laboratory tests on undisturbed soil samples. Because of the different concepts and idealizations in these two approaches, the results are expected to vary significantly. In order to investigate this fact in detail, three-dimensional finite element analyses were carried out using different combinations of soil and pile characteristics. The FE results related to the pile deflections are compared with the closed-form solutions in which the modulus of subgrade reaction $k_s$ is evaluated using the well-known $k_s-E_s$ relationship. In view of the observed discrepancy between the FE results and the closed-form solutions, an improved relationship between the modulus of subgrade reaction and the elastic constants is proposed, so that the solutions from the closed-form equations and the FEA can be closer to each other.

Validation of a non-linear hinge model for tensile behavior of UHPFRC using a Finite Element Model

  • Mezquida-Alcaraz, Eduardo J.;Navarro-Gregori, Juan;Lopez, Juan Angel;Serna-Ros, Pedro
    • Computers and Concrete
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    • 제23권1호
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    • pp.11-23
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    • 2019
  • Nowadays, the characterization of Ultra-High Performance Fiber-Reinforced Concrete (UHPFRC) tensile behavior still remains a challenge for researchers. For this purpose, a simplified closed-form non-linear hinge model based on the Third Point Bending Test (ThirdPBT) was developed by the authors. This model has been used as the basis of a simplified inverse analysis methodology to derive the tensile material properties from load-deflection response obtained from ThirdPBT experimental tests. In this paper, a non-linear finite element model (FEM) is presented with the objective of validate the closed-form non-linear hinge model. The state determination of the closed-form model is straightforward, which facilitates further inverse analysis methodologies to derive the tensile properties of UHPFRC. The accuracy of the closed-form non-linear hinge model is validated by a robust non-linear FEM analysis and a set of 15 Third-Point Bending tests with variable depths and a constant slenderness ratio of 4.5. The numerical validation shows excellent results in terms of load-deflection response, bending curvatures and average longitudinal strains when resorting to the discrete crack approach.

Time-dependent analysis of cable trusses -Part I. Closed-form computational model

  • Kmet, S.;Tomko, M.
    • Structural Engineering and Mechanics
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    • 제38권2호
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    • pp.157-169
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    • 2011
  • In this paper the time-dependent closed-form static solution of the suspended pre-stressed biconcave and biconvex cable trusses with unmovable, movable and elastic or viscoelastic yielding supports subjected to various types of vertical load is presented. Irvine's forms of the deflections and the cable equations are modified because the effects of the rheological behaviour needed to be incorporated in them. The concrete cable equations in the form of the explicit relations are derived and presented. From a solution of a vertical equilibrium equation for a loaded cable truss with rheological properties, the additional vertical deflection as a time-function is determined. The time-dependent closed-form model serves to determine the time-dependent response, i.e., horizontal components of cable forces and deflection of the cable truss due to applied loading at the investigated time considering effects of elastic deformations, creep strains, temperature changes and elastic supports. Results obtained by the present closed-form solution are compared with those obtained by FEM. The derived time-dependent closed-form computational model is used for a time-dependent simulation-based reliability assessment of cable trusses as is described in the second part of this paper.

정위치 해석해를 가지는 병렬 메카니즘에 관한 분석과 혼합구조 매니퓰레이터로의 활용 (Analysis of Parallel Mechanisms with Forward Position Closed-Form Solution with Application to Hybrid Manipulator)

  • 김희국;이병주
    • 제어로봇시스템학회논문지
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    • 제5권3호
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    • pp.324-337
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    • 1999
  • In this work, a new 3-PSP type spatial 3-degree-of-freedom parallel mechanism is proposed. And a 6 DOF hybrid manipulator which consists of a 3-PPR type planar 3 DOF parallel mechanism and a new 3-PSP type spatial 3-degree-of-freedom parallel mechanism is proposed. Both 3 DOF mechanism modules have closed-form forward position solutions and particularly, 3-PSP spatial module has unique forward position solution. Firstly, the closed-form position analysis and first-order kinematic analysis for the proposed 3-PSP type module are carried out, and the first-order kinematic characteristics are examined via maximum singular value and the isotropic index of the mechanism. It is shown through these analyses that the mechanism has excellent isotrpic property throughout the workspace. Secondly, position and kinematic analysis of the 3-PPR planar module are briefly described. Thirdly, the forward position analysis for the 3-PPR 3-PSP type 6 degree-of-freedom hybrid mechanism consisting of a 3-PPR planar module and a 3-PSP spatial module is performed along with the analysis of the workspace size and first-order kinematic characteristics. The kinematic characteristics of the proposed hybrid manipulator are compared to those of geometrically similar Stewart manipulator.

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정확한 Closed-Form 그린함수를 이용한 코플래너 도파로 불연속 해석 (Analysis of Coplanar Waveguide Discontinuities Using Accurate Closed-Form Green's function)

  • 강연덕;송성찬;이택경
    • 한국항행학회논문지
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    • 제7권2호
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    • pp.180-190
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    • 2003
  • 실수축 상의 적분 방법에 의한 정확한 closed-form 그린함수를 이용하여 코플래너 도파로의 불연속에 대한 공간영역 full-wave 해석을 하였다. MPIE(Mixed Potential Integral Equation)를 풀기 위한 수치계산 방법으로는 삼각형 요소를 이용한 갤러킨 방법을 사용하였다. 경계면에서 삼각형 요소상의 기저함수로는 선형함수를 사용하였으며, 관측점과 전원점이 일치하는 특이점 근방의 적분 계산을 위해 면적분을 선적분 형태로 바꾸어 피적분 함수의 특이점이 사라지도록 하는 해석적인 방법을 사용하였다. 실수축 적분방법에 의한 그린함수를 이용함으로써 불연속에 대한 정확한 특성을 구하였다.

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Load-carrying capacities and failure modes of scaffold-shoring systems, Part II: An analytical model and its closed-form solution

  • Huang, Y.L.;Kao, Y.G.;Rosowsky, D.V.
    • Structural Engineering and Mechanics
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    • 제10권1호
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    • pp.67-79
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    • 2000
  • Critical loads and load-carrying capacities for steel scaffolds used as shoring systems were compared using computational and experimental methods in Part I of this paper. In that paper, a simple 2-D model was established for use in evaluating the structural behavior of scaffold-shoring systems. This 2-D model was derived using an incremental finite element analysis (FEA) of a typical complete scaffold-shoring system. Although the simplified model is only two-dimensional, it predicts the critical loads and failure modes of the complete system. The objective of this paper is to present a closed-form solution to the 2-D model. To simplify the analysis, a simpler model was first established to replace the 2-D model. Then, a closed-form solution for the critical loads and failure modes based on this simplified model were derived using a bifurcation (eigenvalue) approach to the elastic-buckling problem. In this closed-form equation, the critical loads are shown to be function of the number of stories, material properties, and section properties of the scaffolds. The critical loads and failure modes obtained from the analytical (closed-form) solution were compared with the results from the 2-D model. The comparisons show that the critical loads from the analytical solution (simplified model) closely match the results from the more complex model, and that the predicted failure modes are nearly identical.

동축선으로 급전되는 마이크로스트립 패치 안테나의 효율적인 수치해석 (Numerically Efficient Analysis of a Coaxial-fed Microstrip Patch Antenna)

  • 이강렬;이영순
    • 한국전자파학회논문지
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    • 제11권1호
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    • pp.124-135
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    • 2000
  • 본 논문에서는 공간영역 closed -form 그런함수를 사용하여 마이크로스트립 구조를 효율적으로 수치해석할 수 있는 방법을 고려해 보고자 한다, 모벤트법을 가용하여 임피던스 행렬의 요소를 구할 때 closed -form 그린함수 를 사용하여 그 계산시간을 현저히 줄일 수 있다는 것은 이미 잘 알려진 사실이다. 그러나 행렬의 대각요소를 구하는 과정에서 그 계산결과가 여전히 느리게 수렴한다는 문제점이 발견되었고, 그 이유는 closed -form 그런함 수에 포함되어 있는 복소지수의 작은 항때문인 것으로 사료된다. 따라서 대각요소 계산시 느린 수렴도의 문제점 을 해소하기 위해 좌표계 변환에 의한 수치적분기법을 고려해 보고자 한다. 본 논문에서 제시한 수치기법들의 타당성을 확인하기 위해 동축선 급전에 의한 마이크로스트립 안테나 산란문제의 해석에 적용하여 기존 논문의 결과와 비교해 볼 때 비교적 잘 일치함을 확인할 수 있었다.

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