• 제목/요약/키워드: Boundedness

검색결과 352건 처리시간 0.024초

선체주위 자유수면 유동 해석을 위한 VOF법 연구 (A VOLUME OF FLUID METHOD FOR FREE SURFACE FLOWS AROUND SHIP HULLS)

  • 박일룡
    • 한국전산유체공학회지
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    • 제20권1호
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    • pp.57-64
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    • 2015
  • This paper describes a volume of fluid(VOF) method, mRHRIC for the simulation of free surface flows around ship hulls and provides its validation against benchmark test cases. The VOF method is developed on the basis of RHRIC method developed by Park et al. that uses high resolution differencing schemes to algebraically preserve both the sharpness of interface and the boundedness of volume fraction. A finite volume method is used to solve the governing equations, while the realizable ${\kappa}-{\varepsilon}$ model is used for turbulence closure. The present numerical results of the resistance performance tests for DTMB5415 and KCS hull forms show a good agreement with available experimental data and those of other free surface methods.

A FORCE/POSITION CONTROL FOR TWO-ARM MOTION COORDINATION AND STABILITY ROBUSTNESS ANALYSIS

  • 최형식
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1992년도 추계학술대회 논문집
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    • pp.215-219
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    • 1992
  • This paper presents a motion coordination of two robot manipulators coordinating an object. To coordinate the object, a force/position control scheme in a mode of leaer/follower is devised. The dynamics of the object are incorporated into the dynamics of the leader arm, which yields a reduced order model of two arm system. In order to regulate interaction forces between two arm, the dynamics of the follower arm are expressed as force dynamic equations such that a novel direct forces between two arms and two different type of bounded input disturbances, boundedness and asymptotic stability results based on a proposed Lyapunov function are shown. Also, a sufficient condition for a stability robustness is derived based on the Lyapunov approach.

반복된 스칼라 블록 파라미터를 포함한 불확실성을 갖는 선형 시스템의 가인 양실 제어 (Robust Positive Real Control of Linear Systems with Repeated Scalar Block Parameter Uncertainty)

  • 이보형;심덕선;이장규
    • 제어로봇시스템학회논문지
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    • 제4권5호
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    • pp.574-578
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    • 1998
  • This paper considers the robust positive real problem for linear systems with linear fractional-type norm-bounded repeated scalar block parameter uncertainty. It is shown that the robust positive real problem can be converted into the standard positive real problem without uncertainty that can be used for the analysis of the given uncertain linear system and the synthesis of a controller that robustly stabilizes and achieves the extended strict positive realness property of the closed-loop transfer function. These results can be also applied to the linear system with general structured uncertainty containing repeated scalar block parameters and are extensions of the previous works that consider only norm-boundedness of the affine unstructured uncertainty.

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불확실성의 Fredholm 적분 수식화를 통한 적응가변구조제어기 설계 (Design of an Adaptive Variable Structure Control using Fredholm Integral Formulae for the Uncertainties)

  • 유동상
    • 제어로봇시스템학회논문지
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    • 제9권9호
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    • pp.658-663
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    • 2003
  • In deterministic design of feedback controllers for uncertain dynamic systems, the upper bound of the uncertainty is very important to guarantee the stability of the closed loop system. In this paper, we assume that the upper bound of the uncertainty is formulated using a Fredholm integral equation of the first kind, that is, an integral of the product of a predefined kernel with an unknown influence function. We propose an adaptation law that is capable of estimating this upper bound. Using this adaptive upper bound, we design an adaptive variable structure control (AVSC), which guarantees asymptotic stability/ultimate boundedness of uncertain dynamic systems. The illustrative example shows the proposed AVSC is effective for uncertain dynamic systems.

신경회로망을 이용한 틸트로터 항공기 SCAS 설계 (Tiltrotor Aircraft SCAS Design Using Neural Networks)

  • 한광호;김부민;김병수
    • 제어로봇시스템학회논문지
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    • 제11권3호
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    • pp.233-239
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    • 2005
  • This paper presents the design and evaluation of a tiltrotor attitude controller. The implemented response type of the command augumentation system is Attitude Command Attitude Hold. The controller architecture can alleviate the need for extensive gain scheduling and thus has the potential to reduce development time. The control algorithm is constructed using the feedback linearization technique. And an on-line adaptive architecture that employs a neural network compensating the model inversion error caused by the deficiency of full knowledge tiltrotor aircraft dynamics is applied to augment the attitude control system. The use of Lyapunov stability analysis guarantees boundedness of the tracking error and network parameters. The performance of the controller is evaluated against ADS-33E criteria, using the nonlinear tiltrotor simulation code for Bell TR301 developed by KARI. (Korea Aerospace Research Institute)

MIMO 비선형 시스템의 로컬 관측기 설계 (Local Observer Design for MIMO Nonlinear Systems)

  • 이성렬
    • 전자공학회논문지SC
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    • 제45권1호
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    • pp.9-14
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    • 2008
  • 본 논문에서는 다입력 다출력 비선형 시스템에 대한 관측기 설계 방법을 제안한다. 먼저 관측기 설계를 위한 삼각구조를 갖는 비선형 시스템을 정의한다. 또한 제안한 관측기의 안정도를 증명하는데 중요한 역할을 하는 가관측성 행렬을 다입력 다출력 시스템으로 확장한다. 확장된 가관측성 행렬을 이용하여 상태변수와 시스템 입력의 유계 조건하에서 제안한 관측기가 로컬 영역에서 지수 함수적 수렴성을 가짐을 증명한다. 마지막으로 제안한 결과의 유효성을 증명하기 위하여 모의실험 예제를 제공한다.

BOUNDEDNESS IN FUNCTIONAL PERTURBED DIFFERENTIAL SYSTEMS VIA t-SIMILARITY

  • Im, Dong Man;Choi, Sang Il;Goo, Yoon Hoe
    • 충청수학회지
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    • 제30권3호
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    • pp.291-304
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    • 2017
  • This paper shows that the solutions to the perturbed differential system $$y^{\prime}=f(t,y)+{{\displaystyle\smashmargin{2}{\int\nolimits_{t_0}}^{t}}g(s,y(s),T_1y(s))ds+h(t,y(t),T_2y(t))$$, have bounded properties by imposing conditions on the perturbed part ${\int}_{t_0}^{t}g(s,y(s),T_1y(s))ds,h(t,y(t),T_2y(t))$, and on the fundamental matrix of the unperturbed system y' = f(t, y) using the notion of h-stability.

다입력 다출력 비선형 시스템의 관측기 설계 및 인덕션 모터에 응용 (An Observer Design for MIMO Nonlinear Systems and Its Application to Induction Motor)

  • 이성렬
    • 제어로봇시스템학회논문지
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    • 제14권1호
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    • pp.42-48
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    • 2008
  • This paper presents an observer design method for a special class of multi input multi output(MIMO) nonlinear systems. First, we characterize the class of MIMO nonlinear systems with a block triangular structure. Also, the observability matrices for SISO nonlinear systems are extended to MIMO systems. By using the generalized observability matrices, it is shown that under the boundedness conditions of system state and input, the proposed observer guarantees the local exponential stability of error dynamics. Finally, its application to induction motor is given to verify the proposed method.

A Robust Adaptive Controller for Markovian Jump Uncertain Nonlinear Systems with Wiener Noises of Unknown Covariance

  • Zhu, Jin;Xi, Hong-Sheng;Ji, Hai-Bo;Wang, Bing
    • International Journal of Control, Automation, and Systems
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    • 제5권2호
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    • pp.128-137
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    • 2007
  • A robust adaptive controller design for a class of Markovian jump parametric -strict-feedback systems is given. The disturbances considered herein include both uncertain nonlinearities and Wiener noises of unknown covariance. And they satisfy some bound-conditions. By using stochastic Lyapunov method in Markovian jump systems, a switching robust adaptive controller was obtained that guarantees global uniform ultimate boundedness of the closed-loop jump system.

새로운 $\sigma$-변형 알고리즘을 사용한 강인한 기준모델 적응제어 (A Robust Model Reference Adaptive Control with a Modified $\sigma$-modification algorithm)

  • 이호진;정종대;최계근
    • 대한전자공학회논문지
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    • 제26권9호
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    • pp.1322-1331
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    • 1989
  • This paper proposes a new adaptation algorithm with which a model reference adaptive control can give a local boundedness of the tracking error applied to a continuous-time linear time-invariant single-input single-output plant whose reduced-order model is of relative degree 1 and whose unmodeled dynamics may be represented in a sigular perturbation form. With the addition of an offset term and an extra adaptation structure, this algorithm is shown to have a robustness property in the sense that this gives zero residual tracking errors when the unmodeled dynamics are disappeared.

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