• 제어로봇시스템학회논문지
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• 제9권2호
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• pp.117-123
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• 2003

Rotational machines such as optical disk drives, hard disk drives, and so on are subject to periodic disturbances caused by their mechanical characteristics. In the meanwhile, it is well known that repetitive control rejects periodic disturbance effectively. This paper presents a practical application of repetitive control to the track-following servo of an optical disk drive. The repetitive control system is composed of two repetitive controllers which compensate for periodic disturbances generated by track geometry and eccentric rotation of disk and a feedback controller stabilizing the feedback loop. A robust stability for all plant uncertainties is proved using linear matrix inequalities (LMIs). In the controller design, a weighting function is introduced for the feedback controller to ensure a minimum loop gain and a sufficient phase margin. The repetitive controllers and the feedback controller are designed by solving an optimization problem which can consider the robust stability condition and the system performance. The developed repetitive control system is implemented in the digital control system with a 16-bit fixed-point digital signal processor (DSP). Through simulation and experiment. The feasibility of the proposed repetitive control system is verified.

• 한국지능시스템학회논문지
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• 제22권5호
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• pp.549-554
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• 2012

본 논문에서는 추정 분산 제약을 갖는 비선형 이산시간에 대한 최적의 퍼지 필터에 대한 내용을 다루고자 한다. 필터를 설계할 때, 추정오차의 분산값은 필터의 성능이 결정하는 변수중 하나다. 이런 분산값에 더욱 강인한 필터를 설계하고자, 분산 제약 조건을 주어 필터를 설계하고자 한다. 먼저, 비선형 모델을 Tagaki-Sugeno 퍼지 모델을 이용하여 선형 모델로 변형한 후, 이 모델을 기반으로 선형 필터를 디자인한다. 이때 필터설계 과정 중 필터의 각 파라미터값을 구하기 위해 상태 추정오차 값은 평균제곱에 제한되며, 상태오차의 정상상태 분산값은 각각의 미리 정한 상한 제한 값 보다 작은 조건에서 필터를 설계하여 선형행렬부등식과 대수 이차 행렬부등식을 이용하여 파라미터값을 구한다. 이렇게 설계된 퍼지 필터는 트럭트레일러 시뮬레이션을 통해 설계 과정과 성능을 보여준다.

• 한국지능시스템학회논문지
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• 제13권5호
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• pp.582-589
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• 2003

본 논문에서는 퍼지 피드백 선형화 제어 시스템에 대한 강인 안정성 해석과 제어기 설계에 대해서 말하고 있다. 제어 대상인 비선형 시스템을 모델링 하는데 있어서 Takagi-Sugeno (TS) 퍼지 모델 기법을 이용하였고, 이때 발생할 수 있는 모델 불화실성과 외란에 대해 그것의 최대 최소 범위를 안다고 가정하였다. 모델링을 통해서 얻어진 폐구간 시스템에 대한 안정성 판별은 Diagonal Norm based Linear Differential Inclusions (DNLDI) 구조를 이용하여 $L_2$ 강인 안정성 해석을 하였다. 또한, 퍼지 피드백 선형화 제어 시스템을 안정화 시키는 최대 이득을 얻기 위하여 LMI 최적화 계산법을 기반으로한 수치 해석법을 제시하였다. 제안된 방법의 효과를 확인하기 위해서 강인 안정성 해석 및 제어 설계에 대한 간단한 모의실험을 하였다.

• 전기학회논문지
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• 제56권3호
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• pp.600-603
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• 2007

We propose a method to estimate the asymptotic stability region(ASR) of a mismatched uncertain variable structure system with a bounded controller. The uncertain system under consideration may have mismatched parameter uncertainties in the state matrix. Using linear matrix inequalities(LMIs) we estimate the ASR and we show the quadratic stability of the closed-loop control system in the estimated ASR. We also give a simple LMI-based algorithm for estimating the ASR. Finally, we give a numerical example in order to show the effectiveness of our method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 D
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• pp.2687-2689
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• 2004

LMI(Linear Matrix Inequalities) technique is implemented to control hybrid bio system with electric element Biological materials such as muscle and tissue are modeled as electrically passive element in the system. State feedback controller for the hybrid system is designed with constrained control input. The hybrid bio electrical system is characterized in terms of the time and frequency.

• 한국소음진동공학회논문집
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• 제14권9호
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• pp.827-836
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• 2004

In this paper, we design a robust multi-objective track-following controller that satisfies transient response specifications and diminishes the influence of sinusoidal disturbance. To this end, a robust control problem with the multiple constraints is considered. We show that a sufficient condition satisfying the robust control problem can be expressed by linear matrix inequalities. Finally, the robust track-following controller can be designed by solving an LMI optimization problem. The effectiveness of the proposed controller design method is verified though experiments.

• Advances in concrete construction
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• 제9권4호
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• pp.407-412
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• 2020

Due to the influence of nonlinearity and time-variation, it is difficult to establish an accurate model of concrete frame structures that adopt active controllers. Fuzzy theory is a relatively appropriate method but susceptible to human subjective experience to decrease the performance. To guarantee the stability of multi-time delays complex system with multi-interconnections, a delay-dependent criterion of evolved design is proposed in this paper. Based on this criterion, the sector nonlinearity which converts the nonlinear model to multiple rule base of the linear model and a new sufficient condition to guarantee the asymptotic stability via Lyapunov function is implemented in terms of linear matrix inequalities (LMI). A numerical simulation for a three-layer reinforced concrete frame structure subjected to earthquakes is demonstrated that the proposed criterion is feasible for practical applications.

• 대한전기학회논문지:시스템및제어부문D
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• 제53권9호
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• pp.622-629
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• 2004

In practical control systems, the capacity of actuators is limited and this degrades the system performances and it is often a source of instability. To use full capacity of actuators, we adopt the gain scheduled control permitting the over saturation in controls. The basic idea of gain scheduled control is to use a higher gain control when the state variables are smaller and a lower gain control when the state variables are larger. First, we derive a constant H control and a reachable set while satisfying the degree of over saturation. Next, we divide this set into nested subsets and find $H_{\infty}$ controls at rack subsets while satisfying the degree of over saturation. Finally, the control gain is applied according to the status of states. Note that all procedures are done by solving linear matrix inequalities(LMI). Finally, we show the validity and applicability of our proposed control using the simulations of a six-story building subjected to the earthquake excitation.

• 한국정밀공학회지
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• 제21권10호
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• pp.109-114
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• 2004

A combined optimal design problem of structural and control systems is discussed by taking a 3-D flexible structure as an object. We consider a minimum weight design problem for structural system and disturbance suppression problem for the control system. The conditions for the existence of controller are expressed in terms of linear matrix inequalities (LMI). By minimizing the linear sum of the normalized structural objective function and control objective function, it is possible to make optimal design by which the balance of the structural weight and the control performance is taken. We showed in this paper the validity of combined optimal design of structural and control systems.

• 전자공학회논문지SC
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• 제40권2호
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• pp.10-18
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• 2003

본 논문은 시간지연을 갖는 퍼지 시스템에 대한 보장 비용과 H/sub ∞/ 외란감쇄 성능을 갖는 퍼지 필터링 문제를 다룬다. 본 연구는 외란감쇄에 대한 확장 L₂ 노옴 제한조건과 LQ 비용함수의 성능 상한치 제한조건을 만족하는 필터링 설계 방법이다. Lyapunov 함수를 이용하여 필터의 존재성에 대한 충분조건을 유도하고 선형행렬부등식(LMI: linear matrix inequality)으로 나타낸다. 필터 설계는 LMI 해를 구함으로써 바로 구할 수 있다. 제안한 방법의 설계 과정을 설명하기 위한 시뮬레이션 예제를 또한 나타낸다.