• Title/Summary/Keyword: Dynamic equation

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THE NUTATION DAMPING CONTROL OF A SPACECRAFT (인공위성의 미동현상 제어에 관한 연구)

  • 이창훈
    • Journal of Astronomy and Space Sciences
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    • v.11 no.2
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    • pp.281-295
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    • 1994
  • In this paper, the Variable Structure System(VSS) theory with new continuous switching dynamic equation is used to design an automatic controller for the active nutation damping in momentum bias stabilized spacecraft. In the application of VSS theory to a linearized multivariable system with the nutation damping systems, there exist some disadvantages such as how to determine the switching gains and how to reduce the chattering phenomina and reaching phase in input and state trajectories. To solve these drawbacks, this paper presents the continuous switching dynamic equation instead of the discontinuous switching logics to obtain the sliding mode. The new design approach is much simpler than the VSS theory. And there do not exist chattering phenomina in this method because the obtained control inputs are continuous. Simultaneously the reaching phase is reduced by a suitable choice of design factor.

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Vibration Analysis of the Beam Structure with a Moving Mass (이동물체에 의한 보 구조물의 진동 해석)

  • 이우식;임강민
    • Computational Structural Engineering
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    • v.8 no.4
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    • pp.57-64
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    • 1995
  • This paper introduced a simple numerical analysis algorithm for the calculation of the dynamic responses of the beam structure with a moving mass. The dynamic equation of motion of the Bernoulli-Euler beam is derived by considering the moving mass as a moving particle, and the dynamic equation of motion is transformed into an integro-differential equation by use of the structural influence function. The numerical solutions of the integro-differential equation are obtained by the modal analysis approach, and compared with those cited from well-known references. The proves that the numerical analysis algorithm proposed herein provide very reliable results, and thus it can be utilized in the design analysis of the beamlike structures exited by a mass which is traveling on it.

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Computer Simulation and Shape Design Sensitivity Analysis of the Valve inside the Reciprocal Compressor using Finite Element Model (유한 요소 모델을 이용한 왕복동식 압축기 밸브의 거동 해석 및 형상 설계 민감도 해석)

  • 이제원;왕세명;주재만;박승일;이성태
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.796-801
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    • 2002
  • The goal of this research is the shape design of the valve using a computer simulation. For an analysis a basic mathematical model describing compression cycle is considered as consisting of five sets of coupled equations. These are the volume equation (kinematics), valve dynamic equation (dynamics), ideal gas equation (thermodynamics), Bernoulli equation (fluid dynamics), and dynamic equation of fluid particle based on Helmholtz equation (acoustics). Valve motion is made by the superposition of free vibration modes obtained by the finite element method. That is, the eigenvalues and eigenvectors are the sufficient modeling factors fur the valve in the simulation program. Thus, to design a shape of the valve, shape design sensitivity through chain-ruled derivatives is considered from two sensitivity coefficients, one is the design sensitivity of the capability of compressor with respect to the eigenvalues of the valve, and the other is the design sensitivity of the eigenvalue with respect to the shape change of the valve. In this research, the continuum design sensitivity analysis concepts are used for the latter.

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An analytical solution for finitely long hollow cylinder subjected to torsional impact

  • Wang, X.;Wang, X.Y.;Hao, W.H.
    • Structural Engineering and Mechanics
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    • v.19 no.3
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    • pp.281-295
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    • 2005
  • An analytical method is presented to solve the elastodynamic problem of finitely long hollow cylinder subjected to torsional impact often occurs in engineering mechanics. The analytical solution is composed of a solution of quasi-static equation satisfied with the non-homogeneous boundary condition and a solution of dynamic equation satisfied with homogeneous boundary condition. The quasi-static solution is obtained directly by solving the quasi-static equation satisfied with the non-homogeneous boundary condition. The solution of the non-homogeneous dynamic equation is obtained by means of finite Hankel transform on the radial variable, r, Laplace transform on time variable, t, and finite Fourier transform on axial variable, z. Thus, the solution for finitely long, hollow cylinder subjected to torsion impact is obtained. In the calculating examples, the response histories and distributions of shear stress in the finitely long hollow cylinder subjected to an exponential decay torsion load are obtained, and the results have been analyzed and discussed. Finally, a dynamic finite element for the same problem is carried out by using ABAQUS finite element analysis. Comparing the analytical solution with the finite element solution, it can be found that two kinds of results obtained by means of two different methods agree well. Therefore, it is further concluded that the analytical method and computing process presented in the paper are effective and accurate.

Robust feedback error learning neural networks control of robot systems with guaranteed stability

  • Kim, Sung-Woo
    • 제어로봇시스템학회:학술대회논문집
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    • pp.197-200
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    • 1996
  • This paper considers feedback error learning neural networks for robot manipulator control. Feedback error learning proposed by Kawato [2,3,5] is a useful learning control scheme, if nonlinear subsystems (or basis functions) consisting of the robot dynamic equation are known exactly. However, in practice, unmodeled uncertainties and disturbances deteriorate the control performance. Hence, we presents a robust feedback error learning scheme which add robustifying control signal to overcome such effects. After the learning rule is derived, the stability is analyzed using Lyapunov method.

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Linearity and Nonlinearity of Rotor System Analysis (로터 시스템 회전운동 선형 및 비선형성)

  • Yun, Seong-Ho;Ren, Li-Min
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.190-196
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    • 2008
  • The dynamical rotor system is investigated through the derivation and formulations of the dynamic equation of the rotating system in terms of both inertial and fixed frame of the system as well as quaternion. The investigation is aimed at analyzing the dynamical rotating system precession speed. The resulting equations of motion consist of the consistent mass matrix and gyroscopic matrix. The formulation shows its features and difference between its linearity and nonlinearity.

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Design of Attitude Estimator and Controller for Multi-Purpose Satellite under Torque Disturbance (Torque Disturbance를 받는 다목적 위성의 자세추정기 및 제어기 설계)

  • Kim, Min-Sung;Choi, Wan-Shik;Oh, Hwa-Suk;Heo, Hoon
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.113-118
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    • 1996
  • Nonlinear Attitude Dynamic Equation for rigid-body satellite is derived and linearzed. Estimator using Kalman filter and controller are designed. Controller using LQR technique implemented on satellite under torque disturbance shows much better performance than those by using of Bang-Bang technique.

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Fuzzy Modelling and Control of Nonlinear Systems Using a Genetic Algorithm (유전알고리즘을 이용한 비선형시스템의 퍼지 모델링 및 제어)

  • Lee, Hyun-Sik;Jin, Gang-Gyoo
    • Proceedings of the KIEE Conference
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    • pp.581-584
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    • 1998
  • This paper presents a scheme for fuzzy modelling and control of continuous-time nonlinear systems using a genetic algorithm. A fuzzy model is characterized by fuzzy "if-then" rules whose consequence part has a linear dynamic equation as subsystem of the system. The parameters of the fuzzy model are adjusted by a genetic algorithm. Then a tracking controller which guarantees stability of the overall system is designed. The simulation result demonstrates the effectiveness of the proposed method.

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Dynamic Characteristics Simulation for Magnetically-Levitated Vehicle (자기부상열차의 동특성 시뮬레이션)

  • Kim, Jong-Moon;Kim, Choon-Kyung;Park, Min-Kook
    • Proceedings of the KIEE Conference
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    • pp.1134-1135
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    • 2006
  • In this paper, dynamic simulation results for magnetically-levitated vehicles are resented. The dynamic equation and models for a half-bogie system are derived. The system includes primary suspension system, magnet module, spring-damper system and cabin. Also, the dynamic characteristics for the derived models are analysed. Using the results, levitation control algorithm can be designed to meet the performance requirements.

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GA-based Fuzzy Modelling of Nonlinear Systems (비선형시스템의 유전알고리즘에 기초한 퍼지 모델링)

  • 이현식;진강규
    • Proceedings of the Korean Institute of Intelligent Systems Conference
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    • pp.368-373
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    • 1998
  • This paper presents a GA-based fuzzy modelling scheme of nonlinear systems. The fuzzy model is a type of the Sugeno-Tagaki's fuzzy model whose consequence parts are described by a linear continuous dynamic equation as subsystem of a nonlinear system. The centers and width of the membership functions of the fuzzy sets defined over the input space and the orders and parameters of subsystems in the consequence parts are adjusted by a genetic algorithm. The effectiveness of the proposed method is verified

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