• 대한기계학회논문집
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• 제18권2호
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• pp.278-291
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• 1994

A computer-aided robust design (CARD) technique is developed to search for the design variables, optimal as well as robust in the sense of Taguchi method. The CARD technique can effectively handle inequality problems by employing the variable penalty method, and dynamic problems with many design variables and/or with mixed discrete and continuous variables. It is also capable of providing contributions of each design variables to the object funtion and information for future designs. As the illustrative examples, two dynamic systems, engine mounting system and in-line feeder, are treated.

• Kyungpook Mathematical Journal
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• 제49권4호
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• pp.595-603
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• 2009

We show that for an algebraic Riccati equation $X^*B^{-1}X-T^*X-X^*T=C$, its solutions are given by X = W + BT for some solution W of $X^*B^{-1}X$ = $C+T^*BT$. To generalize this, we give an equivalent condition for $\(\array{B&W\\W*&A}\)\;{\geq}\;0$ for given positive operators B and A, by which it can be regarded as Riccati inequality $X^*B^{-1}X{\leq}A$. As an application, the harmonic mean B ! C is explicitly written even if B and C are noninvertible.

• Journal of Power Electronics
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• 제12권2호
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• pp.294-304
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• 2012

This paper proposes a fuzzy speed tracking controller and a fuzzy rotor angular acceleration observer for a surface-mounted permanent magnet synchronous motor (SPMSM) based on the Takagi-Sugeno (T-S) fuzzy model. The proposed observer-based controller is robust to load torque variations since it utilizes rotor angular acceleration information instead of the load torque value. Linear matrix inequality (LMI) sufficient conditions are given to compute the gain matrices of the speed tracking controller and the observer. In addition, it is mathematically verified that the proposed observer-based control system is asymptotically stable. Simulation and experimental results are presented to confirm that the proposed control algorithm assures a better transient behavior and less sensitivity under model parameter variations than the conventional PI control method.

• Journal of Electrical Engineering and information Science
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• 제3권2호
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• pp.163-169
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• 1998

In this paper, we consider the problem of designing H$\infty$ state feedback controller for the generalized time systems with delayed states and control inputs in continuous and discrete time cases, respectively. The generalized time delay system problems are solved on the basis of LMI(linear matrix inequality) technique considering time delays. The sufficient condition for the existence of controller and H$\infty$ state feedback controller design methods are presented. Also, using some changes of variables and Schur complements, the obtained sufficient condition can be rewritten as a LMI form in terms of transformed variables. The propose controller design method can be extended into the problem of robust H$\infty$ state feedback controller design method easily.

• 제어로봇시스템학회논문지
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• 제20권10호
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• pp.995-1001
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• 2014

In the aftermath of the financial crisis of 2008, while numerous members of the general public lost their homes and jobs, many of the largest banks held responsible for the crisis have been successfully rescued by bailouts. In this paper, through the analysis of income inequality, unemployment, tax cuts, and bailouts, we show that the interests of the general public are different from the interests of politicians and bankers. While the small elite group of politicians and bankers could set the deregulation policies with inordinate power based on full information, most people were ignorant and unconcerned about the policies, and hence did not oppose them. Specifically, we model the credit change in the financial markets of the United States by a finite state machine, and design three local supervisors representing three groups with different interests. It is then shown that the deregulation policies were adopted according to the difference of the supervisors' powers.

• 전자공학회논문지S
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• 제36S권5호
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• pp.30-41
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• 1999

본 논문에서는 연속시간과 이산시간에서 파라미터 불확실성과 시간지연을 가지는 비선형시스템에 대한 퍼지 견실 H∞ 제어기 설계방법을 제시한다. 비선형시스템은 변형한 T-S(Takagi- Sugeno) 퍼지모델을 사용하여 나타내고, 퍼지제어는 PDC(parallel distributed compensation) 개념을 이용한다. 또한 Lyapunov 접근방법을 이용하여 불확실성, 외란과 시간지연을 가지는 변형한 T-S 퍼지모델의 H∞ 노옴 한계를 가지는 자승적 안정성을 언급하고, LMI(linear matrix inequality) 기법을 이용하여 퍼지 견실 H∞ 제어기의 존재 조건과 제어기 설계방법을 제시한다. 그러므로 제시한 기법은 구하여진 충분조건을 만족하는 해를 찾음과 동시에 제어기를 한번에 설계할 수 있다. 마지막으로 예제를 통하여 제시한 방법의 타당성을 확인한다.

• 전자공학회논문지SC
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• 제40권5호
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• pp.326-332
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• 2003

본 연구에서는 상태변수에 시변 시간지연을 가진 선형시스템의 모델 차수축소를 취급한다. 이를 위하여 시간지연 시스템의 일반화 가제어성/가관측성 그래미안을 선형행렬 부등식의 해를 이용하여 정의하고 균형화된 상태공간 구현을 정의한다. 균형화된 상태공간 구현으로부터 상태변수론 절삭하여 차수축소된 시간지연 시스템을 구하고 모델 축소오차의 상한치를 제시한다. 수치예를 통하여 제시된 방법의 효용성을 입증한다.

• 전자공학회논문지SC
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• 제47권4호
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• pp.1-6
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• 2010

본 논문에서는 상태에 시변 시간지연과 폴리토픽 변수 불확실성을 가지는 특이시스템을 위한 새로운 지연 종속 및 변수 종속 강인 안정성 조건을 제시한다. 새로운 변수종속 리아푸노프 함수를 기반으로 구한 강인 안정성 조건은 볼록최적화가 가능한 선형행렬부등식으로 나타난다. 제안하는 조건은 비특이시스템과 특이시스템의 강인 안정성 문제에 동시에 적용가능한 일반적인 알고리듬이다. 수치예제를 통하여 제시한 강인 안정성 조건의 타당성을 보이고, 기존의 비특이시스템의 결과들과의 비교를 통하여 제안한 조건이 덜 보수적임을 확인한다.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2005년도 춘계학술대회 학술발표 논문집 제15권 제1호
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• pp.378-381
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• 2005

This paper presents a new linear-matrix-inequality-based intelligent digital redesign (LMI-based IDR) technique to match the states of the analog and the digital T-S fuzzy control systems at the intersampling instants as well as the sampling ones. The main features of the proposed technique are: 1) the fuzzy-model-based periodic control is employed, and the control input is changed n times during one sampling period; 2) The proposed IDR technique is based on the approximately discretized version of the T-S fuzzy system, but its discretization error vanishes as n approaches the infinity. 3) some sufficient conditions involved in the state matching and the stability of the closed-loop discrete-time system can be formulated in the LMIs format.

• KIEE International Transaction on Systems and Control
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• 제2D권2호
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• pp.72-77
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• 2002

Delay and noise in networked control systems are inevitable and can degrade system performance or stability This paper propose a compensation method for networked control systems with network-induced delay and noise using LMI(linear matrix inequality)-based H_\infty optimization. The H_\infty optimization methods have adapted to account for both the time delay and noise effects. Some simulations applied to inverted pendulum with networked control show that the proposed method works well.