• Journal of the Korean Institute of Intelligent Systems
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• v.22 no.1
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• pp.28-35
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• 2012

This paper presents the method for $H_{\infty}$ fuzzy controller design of discrete-time fuzzy Markovian jump systems with state and input time delays. The Takagi and Sugeno fuzzy model is employed to represent a delayed nonlinear system that possesses Markovian jump parameters. A stochastic mode dependent Lyapunov function is employed to analyze the stability and $H_{\infty}$ disturbance attenuation performance of the fuzzy Markovian jump systems with state and input time delays. A sufficient condition for the existence of fuzzy $H_{\infty}$ controller is given in terms of matrix inequalities. Also numerical example is presented to illustrate the efficiency of the proposed design method.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.121-128
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• 2000

The scope of this paper is focused to the systems which have the time period and they should be necessarily studied in the sense of stability and design method of controller to stabilize the orignal unstable systems. In general, the time periodic systems or the systems having same motions during certain time interval are easily found in rotating motion device, i.e., satellite or helicopter and widely used in factory automation systems. The characteristics of the selected dynamic systems are analyzed with the new stability concept and stabilization control method based on Lyapunov direct method. The new method from Lyapunov stability criteria which satisfies the energy convergence is studied with linear algebraic method. And the numerical procedures are developed with computational programming method to apply to the practical linear periodic systems. The results from this paper demonstrate the usefulness in analysis of the asymptotic stability and stabilization of the unstable linear periodic system by using the developed simulation procedures.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.171-179
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• 2001

The purpose of this paper is the derivation and development of the new definitions and methods for the new estimation of robustness for the systems having structured uncertainties. This proposition adopts the theoretical analysis of the Lyapunov direct methods, that is, the sign properties of the Lyapunov function derivative integrated along finite intervals of time, in place of the original method of the sign properties of the time derivative of the Lyapunov function itself. This is the new sufficient criteria to relax the stability condition and is used to generate techniques for the robust design of control systems with structured perturbations. The systems considered are assumed to be nominally linear, with time-variant, nonlinear bounded perturbations. This new techniques demonstrate the improvement of robustness bounds from the numerical results.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.443-444
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• 2008

본 논문에서는 비행기 모델을 대상으로 invariance and immersion방법을 적용하여 비선형 제어기를 설계한다. 이 방법을 사용하면 추정오차에 대한 추정식 형태로 off-the-manifold 좌표축을 정의하고, dynamics를 구하고, 이로부터 파라미터 적응규칙을 유도한다. 제어기는 이와 관련된 파라미터로부터 선형 화하지 않고 직접 설정하며, 마지막으로 리아프노프 함수를 통하여 알고리즘의 안정성을 증명한다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2926-2934
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• 2000

This study presents a direct adaptive controller which is derived by using Lyapunovs direct methods for trajectory tracking control of a pneumatic cylinder. The structure of the controller is very simple and computationally efficient because it does not use either the dynamic model or the parameter values of the pneumatic system. The bounded stability of the system is shown in the presence of the bounded unmodeled dynamics. The bounded size of tracking errors can be made arbitrarily small without giving andy influences on either input or output variables. The trajectory tracking performance and the stability of the control system is verified experimentally. The results of the experiments show that the proposed controller tracks the given trajectories, sine function and cycloidal function trajectories, more accurately than PD controller does, and it stabilizes the system and adaptive variables.

• Journal of Institute of Control, Robotics and Systems
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• v.1 no.1
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• pp.1-3
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• 1995

결합된 시변 상미분 방정식의 해외 점근적 성질에 관한 연구이다. 리아프노프 직접 방법에 의하면 평등 안정성(uniform stability)만 얻어졌을 경우이지만, 추가적으로 상태 벡터 중 일부가 0으로 점근적 수렴함을 보이는데 있다. 얻어진 결과는 특히 불변원리(invariance principle)가 성립하지 않는 시변 시스템에 유용하다.