• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 학술대회 논문집 정보 및 제어부문
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• pp.235-236
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• 2008

This paper is concerned with the stabilization problem of Markovian jump nonlinear systems with time-delay via Takagi-Sugeno (T-S) fuzzy control approach. The T-S fuzzy models are employed to represent nonlinear systems with Markovian jump parameters and time-delay. The purpose of this paper is to design a mode-independent fuzzy controller such that the closed-loop Markovian jump fuzzy system is stochastically stable. Based on a stochstic Lyapunov function, stabilization sufficient conditions using a mode-independent fuzzy controller are derived for the Markovian jump fuzzy system in terms of Linear Matrix Inequalities (LMIs). Finally, a simulation example is presented to illustrate the effectiveness of the proposed method.

• International Journal of Control, Automation, and Systems
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• 제4권3호
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• pp.293-301
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• 2006

A new discretization method for calculating a sampled-data representation of a nonlinear continuous-time system is proposed. The proposed method is based on the well-known Taylor series expansion and zero-order hold (ZOH) assumption. The mathematical structure of the new discretization method is analyzed. On the basis of this structure, a sampled-data representation of a nonlinear system with a time-delayed input is derived. This method is applied to obtain a sampled-data representation of a non-affine nonlinear system, with a constant input time delay. In particular, the effect of the time discretization method on key properties of nonlinear control systems, such as equilibrium properties and asymptotic stability, is examined. 'Hybrid' discretization schemes that result from a combination of the 'scaling and squaring' technique with the Taylor method are also proposed, especially under conditions of very low sampling rates. Practical issues associated with the selection of the method parameters to meet CPU time and accuracy requirements are examined as well. The performance of the proposed method is evaluated using a nonlinear system with a time-delayed non-affine input.

• 제어로봇시스템학회논문지
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• 제8권7호
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• pp.578-583
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• 2002

This paper presents a method for designing fuzzy $H_2/H_{\infty}$ controllers of nonlinear systems with time varying delay. Takagi-Sugeno fuzzy model is employed to represent nonlinear systems with time varying delay. Using a single quadratic Lyapunov function, the globally exponential stability and $H_2/H_{\infty}$ performance problem are discussed. A sufficient condition for the existence of fuzzy $H_2/H_{\infty}$ controllers is then presented in terms of linear matrix inequalities(LMls). The proposed fuzzy $H_2/H_{\infty}$ controllers minimizes the upper bound on the linear quadratic performance measure.

• 제어로봇시스템학회논문지
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• 제15권4호
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• pp.413-419
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• 2009

A decentralized adaptive control method is proposed for large-scale systems with unknown time-delayed nonlinear interconnections unmatched in control inputs. It is assumed that the time-delayed interaction terms are bounded by unknown nonlinear bounding functions. The nonlinear bounding functions and uncertain nonlinear functions of large-scale systems are compensated by the function approximation technique using neural networks. The dynamic surface control method is extended to design the proposed memoryless local controller for each subsystem of uncertain nonlinear large-scale time delay systems. Therefore, although the interconnected systems consist of a large number of subsystems, the proposed controller can be designed simply. We prove that all the signals in the total closed-loop system are semiglobally uniformly bounded and the control errors converge to an adjustable neighborhood of the origin. Finally, an example is given to demonstrate the effectiveness and applicability of the proposed scheme.

• Transactions on Control, Automation and Systems Engineering
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• 제1권1호
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• pp.22-31
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• 1999

In this paper, a robust observer design method for nonlinear multi input multi-output(MINO) plants is presented. This method enables the extension of the time delay observer (TDO) for nonlinear SISO plants in the phase variable form to MIMO plants. The designed TDO reconstructs the states of the plant expressed in the generalized observability canonical form (GOBCF), yet requiring neither the transformation of a plant, nor the real time computation coordinates, the observer turned out to be computationally efficient and easy to design for nonlinear MIMO plants. In a simulation of a two-link manipulator with flexible joints, the control performances using TDO appeared to be similar to those using actual states and superior to those using numerical differentiation. Finally, in an experiment with a robot, it was confirmed that the TDO reconstructs the states reliability and TDO can be effectively used in a real closed-loop system.

• 한국지능시스템학회논문지
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• 제15권3호
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• pp.324-329
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• 2005

본 논문에서는 시간 지연을 갖는 이산 시간 비선형 시스템을 $H\infty$ 의미에서 안정하게 하는 정적 출력 제한 퍼지 제어기 설계를 제시한다. 먼저 대상이 되는 비선형 시스템은 Takagi-Sugeno 퍼지 모델로 표현 되어진다. 그리고 parallel distributed compensation technique을 이용하여 퍼지 제어기의 형태를 만든다. 하나의 Lyapunov 함수를 정하여서 폐루프 시스템의 전역 점근적 안정성과 외란에 대한 강인성을 bilinear matrix inequality 형태로 제시한다. 그리고 합동변환법과 동질성 변환법을 통해 이것을 선형 행렬 부등식 (linear matrix inequality) 으로 표현한다. 제안된 방법의 효율성과 가능성을 보여주기 위해 한 예제를 포함한다.

• 한국지능시스템학회논문지
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• 제18권6호
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• pp.762-767
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• 2008

본 논문에서는 TS 퍼지 모델로 표현되는 시간 지연 비선형 시스템에 대한 $L_{\infty}$ 이득 상태 제한 퍼지 제어기를 제안한다. 이 위해 먼저 TS 퍼지 모델을 이용하여 시간 지연 비선형 시스템을 모델링한다. 다음 이 퍼지 모델을 기본으로 $L_{\infty}$ 이득을 얻기위해 퍼지 상태 궤환 제어기를 설계한다. 마지막으로 $L_{\infty}$ 이득을 얻기 위한 충분조건을 유도한다. 충분조건은 선형 행렬 부등식의 형태로 공식화 한다. 마지막으로 몇 가지 예제를 통하여 제안된 제어기의 효율성을 증명한다.

• International Journal of Control, Automation, and Systems
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• 제2권1호
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• pp.76-82
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• 2004

A robust fuzzy controller is designed to stabilize a class of solvable nonlinear descriptor systems with time-varying delay. First, a new modeling and control method for nonlinear descriptor systems is presented with a fuzzy descriptor model. A sufficient condition for the existence of the fuzzy controller is given in terms of a series of LMIs. Then, a less conservative fuzzy controller design approach is obtained based on the fuzzy rules and weights. This method includes the interactions of the different subsystems into one matrix. The effectiveness of the presented approach and the design procedure of the fuzzy controller are illustrated by way of an example.

• 전자공학회논문지
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• 제50권7호
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• pp.253-257
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• 2013

본 논문은 지연된 출력과 미지의 외란을 갖는 비선형 시스템에 대한 강인 관측기 설계방법을 제안한다. 지연된 출력의 존재에도 불구하고 관측기의 추정오차에 대한 외란의 효과를 원하는 수준까지 줄일 수 있음을 보인다. 강인 관측기의 존재조건은 시간 지연 값에 의존적인 선형행렬 부등식을 이용하여 제시한다. 마지막으로 제안한 결과의 유효성을 증명하기 위하여 수치 예제를 제공한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1414-1417
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• 2003

In this paper, sliding mode controller for discrete-time nonlinear systems with uncertainties and disturbances are proposed. The concept of time-delay control (TDC) which consists of estimating the uncertain dynamics of the system through past observations of the system response is used. The proposed controller guarantees that the closed-loop system states are globally uniformly ultimately bounded (GUUB). It is also shown that the closed-loop system states are globally uniformly asymptotically stable (GUAS) if uncertainties are constant.