• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.7-14
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• 2000

This paper describes the synthesis of robust decentralized controllers for uncertain large-scale discrete-time systems with time-delays in subsystem interconnections. Based on the Lyapunov method, a sufficient condition for robust stability, is derived in terms of a linear matrix inequality (LMI). The solutions of the LMI can be easily obtained using various efficient convex optimization techniques. A numerical example is given to illustrate the proposed method.

• Journal of the Korean Institute of Telematics and Electronics
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• v.19 no.2
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• pp.31-37
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• 1982

A practical and robust control scheme is suggested for MIMO disciete time processes with real simple poles. This type of control scheme, having the advantages of both the adaptiveness and optimality, maybe successfully applicable to structured dynamic controllers for plants whose paiameters are slowly timevaiying. The identiflcation of the process paiameters is undertaken in ARMA form and the optimization of the feedback gain matrix is performed in the state space representation with respect to a standard quadratic criterion.

• Journal of Advanced Marine Engineering and Technology
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• v.31 no.4
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• pp.462-467
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• 2007

The design and synthesis of a state feedback controller assumes the feedback of all state variables of the system. However, some state variables are not physical quantifies so that sensors may not be available, or may be too expensive to measure. Hence, a state observer can be an alternative to estimate unmeasurable state variables. This paper therefore presents a scheme for state observer-based stabilization control of inverted pendulum systems. The feedback gain matrices of both the state feedback controller and the state observer are tuned by real-coded genetic algorithms(RCGAs) such that the given performance indices are minimized. The proposed method is demonstrated through simulations.

• Proceedings of the KIEE Conference
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• 2008.10b
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• pp.458-459
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• 2008

이 논문은 자기부상열차 속력에 따른 부상제어기 성능을 분석한다. 현재 실용화 사업은 시속 110km/h 속력으로 부상공극 8 mm 기준으로 상하 3 mm 이하 변화를 목표로 개발 중에 있다. 부상제어기의 안정성에 영향을 미치는 외란으로는 가이드웨어 처짐, 크로스아암에 의한 레일 처짐, 레일 불균일, 레일 연결부 단차 등이 있다. 이러한 외란이 복합적으로 작용하지만, 설계 단계에서 각각의 영향을 단순화하여 독립적으로 그 영향을 분석할 필요가 있다. 본 논문에서는 차량속력에 따른 가이드웨어 처짐이 부상제어기에 미치는 영향을 분석한다. 하나의 전자석과 유연레일을 모델링하고 상태궤환을 갖는 제어기를 제안하여 속력에 따른 부상공극 변화를 관찰한다. 모의시험 결과 12 mm 레일의 휘어짐 상황에서 속력에 따라 부상 공극 변화가 커지지만, 실용화 사업의 목표를 달성함을 알 수 있었다.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.5 no.3
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• pp.64-71
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• 1991

본 논문에서는 계장제어 터어보 발전기 시스템에 대한 강인제어 문제가 연구되었다. Riccati형 행렬 방정식과 상태궤환을 이용해 센서 고장시 고장된 루프에 관계없이 2입력 2출력터어보-발전기 시스템이 안정하게 제어될 수 있는 방법을 제안하고 보전성을 갖지 않는 경우와 시뮬레이션을 통해 이를 비교 입증하였다. 그 결과 보전성을 고려하지 않고 설계된 이득에 의한 폐 루프 시스템은 고장에 대해 매우 불안정한 응답을 보인 반면 제안된 기법에 의해 보전성을 갖도록 설계한 이득에 의한 폐 루프 시스템에서는 고장에 관계없이 안정한 응답을 나타내어 구조가 복잡한 다변수 시스템의 강인 제어에 응용될 수 있음을 잘 입증하고 있었다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.05a
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• pp.420-424
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• 2006

본 논문에서는 외란을 갖는 불확실한 비선형 시스템을 제어하기 위하여 $H^{\infty}$ 제어를 이용한 강인 간접 적응 퍼지 관측기를 설계하여 상태변수를 관측하고 외란관측기를 설계하여 시스템의 외란을 제거하는 강인한 제어기를 구성한다. 제안된 외란관측기는 시스템과 외란의 대역폭보다 큰 궤환 이득을 가짐으로써 기존의 역플랜트 모델 또는 퍼지 기반의 외란관측기 보다 간단한 구조를 가지고 외란과 시스템 모델링 오차의 합을 관측해 낼 수 있다. 본 논문에서는 도립진자 시스템의 모의실험을 통하여 관측기, 외란관측기와 제어기의 성능을 평가한다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.947-959
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• 2001

We propose a control scheme to control the indoor zone temperature via variable air volume (VAV) unit. To control the room temperature, state space model of the conditioned zone which is partitioned into nine artificial sectional regions is derived. The nonlinearity of the damper motion and actuator are considered for the practical use in the state space system description. The temperature control of the room temperature is performed by manipulating the degree of openness of the damper in relation to the local room temperature and the supplied air flow rate. In general, since a local temperature in the conditioned zone is measured, it is required to estimate the temperature values in each regions for the precise temperature control. We thus design a state observer to estimate the regional temperature, and use these values in the controller. The overall control system consists of the state observer based state feedback with the integral control. We compared the control results of the proposed scheme with those of cascade proportional and integral (PI) control, and showed that the scheme achieved precise control of the conditioned system.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.7
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• pp.539-548
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• 1989

This paper describes an instantaneous reactive power compensator aimed at the compensation of reactive power and current harmonics of a thyristor load. A new definition of the instantaneous reactive power consisting of both displacement of fundamental current and harmonic distortion current is proposed and the physical meaning is investigated from the viewpoint of an instantaneous power flow. The instantaneous reactive power is calculated from the feedback of instantaneous voltage, current and is compensated by the current controlled PWM converter connected in parallel with the load. The PWM converter operates as a high performance current control scheme, because adopts the excellent current controlled PWM technique based on the current deviation vector. Both simulation and experimental results show good compensating performances in steady and transient state.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.332-335
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• 1997

In the industrial motor drive system, a shift torsional vibration si often generated when a motor and a load are connected with a flexible shaft. This paper treats the vibration suppression control of such a system. In this paper, the state feedback controller of the two-mass resonant system using the H$\infty$ filter is proposed. The H$\infty$ filter is robust in noise and disturbance. Simulation results show the validity proposed controller.

• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.273-275
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• 1992

A dynamic system containing uncertain elements is considered. The upper bound of the values of these uncertainties is estimated. Using the estimated value a bounded error state feedback control is proposed based on Corless and Leitmann's result [1].