• 한국지능시스템학회논문지
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• 제26권4호
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• pp.308-315
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• 2016

본 논문은 이산시간 장주기모델로 구성된 다개체시스템의 타카기-수게노(Takagi-Sugeno: T-S) 퍼지 군집제어 기법을 제안한다. 이산시간 모델은 오일러(Euler) 방법을 이용하여 유도한다. 이에 대한 T-S 퍼지 모델은 피드백 선형화 기법을 통해 구성하며, 이를 점근적으로 안정화하기 위한 퍼지제어기를 설계한다. 제어기 설계조건은 선형행렬부등식의 형태로 표현된다.

• Journal of Power Electronics
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• 제16권3호
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• pp.1025-1035
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• 2016

Luenberger observer (LO)-based sensorless multi-loop control of a converter requires an iterative trial-and-error design process, considering that many parameters should be determined, and loop gains are indirectly related to the closed-loop characteristics. Robust H∞ control adopts a compact sensorless controller. The algebraic Riccati equation (ARE)-based and linear matrix inequality (LMI)-based H∞ approaches need an exhaustive procedure, particularly for a low-order controller. Therefore, in this study, a novel robust H∞ synthesis approach is proposed to design a low-order sensorless controller for boost converters, which need not solve any ARE or LMI, and to parameterize the controller by an adjustable parameter behaving like a "knob" on the closed-loop characteristics. Simulation results show the straightforward closed-loop characteristics evaluation and better dynamic performance by the proposed H∞ approach, compared with the LO-based sensorless multi-loop control. Practical experiments on a digital processor confirmed the simulation results.

• 제어로봇시스템학회논문지
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• 제6권1호
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• pp.25-34
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• 2000

In this paper, we design a H^\infty servo controller for gauge control of tandem cold mill. To improve the performance of the AGC(Aotomatic Gauge Control) system based on the Taylor linearized model of tandem cold mill, the H^\infty servo controller is designed to satisfy robust stability, disturbance attenuation and robust tracking properties. The H^\infty servo controller problem is modified as an usual H^\infty control problem, and the solvability condition of the H^\infty servo problem depends on the solvability of the modified H^\infty control problem. Since this modified problem does not satisfied standard assumptions for the H^\infty control problem, it is solved by an LMI(Linear Matrix Inequality) technique. Consequently, the comparison between the H^\infty servo controller and the existing PID/FF(FeedForward) controller shows the usefulness of this study.

• Structural Engineering and Mechanics
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• 제56권3호
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• pp.385-407
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• 2015

This paper deals with the problem of the global stabilization for a class of tension leg platform (TLP) nonlinear control systems. It is well known that, in general, the global asymptotic stability of the TLP subsystems does not imply the global asymptotic stability of the composite closed-loop system. Finding system parameters for stabilizing the control system is also an issue need to be concerned. In this paper, we give additional sufficient conditions for the global stabilization of a TLP nonlinear system. In particular, we consider a class of NN based Takagi-Sugeno (TS) fuzzy TLP systems. Using the so-called parallel distributed compensation (PDC) controller, we prove that this class of systems can be globally asymptotically stable. The proper design of system parameters are found by a swarm intelligence algorithm called Evolved Bat Algorithm (EBA). An illustrative example is given to show the applicability of the main result.

• 한국지능시스템학회논문지
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• 제25권6호
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• pp.615-620
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• 2015

본 논문에서는 화력발전소 보일러-터빈 제어시스템의 고장검출 시스템을 설계한다. 이를 위하여 보일러-터빈의 비선형 동특성을 측정 가능한 시변 파라메터를 갖는 T-S 퍼지시스템으로 나타내고 관측기 기반의 고장검출 필터를 사용하여 오차발생기를 설계한다. 고장발생 측정기를 식별하기 위하여 고장검출 필터 출구에 근사적인 역시스템을 연결하였다. 제시한 방법의 효용성을 컴퓨터 모의실험을 통하여 입증한다.

• 한국정보통신학회논문지
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• 제11권2호
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• pp.316-321
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• 2007

[ $H{\infty}$ ] 제어기는 외란이나 잡음에 대해서 강인한 성능을 가지고 있지 만 파라미터 불확실성이 존재하면 제어입력을 구하기가 쉽지 않으며 불확실성의 영향에 따라서 제어 성능에 큰 차이를 보인다. 하지 만 슬라이딩 모드제어는 파라미터 불확실성에 대하여 우수한 강인성을 가지고 있는 제어 기법이다. 그러므로 본 논문에서는 슬라이딩 모드 제어기법을 도입하여 LMI를 이용한 $H{\infty}$ 제어기의 강인성을 향상시킬 수 있는 제어 기법을 제안한다.

• 대한수학회지
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• 제58권6호
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• pp.1385-1405
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• 2021

Let A be a positive bounded linear operator acting on a complex Hilbert space (𝓗, ⟨·,·⟩). Let ω_A(T) and ║T║_A denote the A-numerical radius and the A-operator seminorm of an operator T acting on the semi-Hilbert space (𝓗, ⟨·,·⟩_A), respectively, where ⟨x, y⟩_A := ⟨Ax, y⟩ for all x, y ∈ 𝓗. In this paper, we show with different techniques from that used by Kittaneh in [24] that $$\frac{1}{4}{\parallel}T^{{\sharp}_A}T+TT^{{\sharp}_A}{\parallel}_A{\leq}{\omega}^2_A(T){\leq}\frac{1}{2}{\parallel}T^{{\sharp}_A}T+TT^{{\sharp}_A}{\parallel}_A.$$ Here T^#_A denotes a distinguished A-adjoint operator of T. Moreover, a considerable improvement of the above inequalities is proved. This allows us to compute the 𝔸-numerical radius of the operator matrix $\(\array{I&T\\0&-I}\)$ where 𝔸 = diag(A, A). In addition, several A-numerical radius inequalities for semi-Hilbert space operators are also established.

• Smart Structures and Systems
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• 제24권1호
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• pp.67-81
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• 2019

Rows of closely adjacent buildings with similar dynamic characteristics are common building arrangements in residential areas. In this paper, we present a vibration control strategy for the seismic protection of this kind of multibuilding systems. The proposed approach uses an advanced Linear Matrix Inequality (LMI) computational procedure to carry out the integrated design of distributed multiactuation schemes that combine interbuilding linking devices with interstory actuators implemented at different levels of the buildings. The controller designs are formulated as static output-feedback H-infinity control problems that include the interstory drifts, interbuilding approachings and control efforts as controlled-output variables. The advantages of the LMI computational procedure are also exploited to design a fully-decentralized velocity-feedback controller, which can define a passive control system with high-performance characteristics. The main ideas are presented by means of a system of three adjacent five-story identical buildings, and a proper set of numerical simulations are conducted to demonstrate the behavior of the different control configurations. The obtained results indicate that interstory-interbuilding multiactuation schemes can be used to design effective vibration control systems for adjacent buildings with similar dynamic characteristics. Specifically, this kind of control systems is able to mitigate the vibrational response of the individual buildings while maintaining reduced levels of pounding risk.

• Smart Structures and Systems
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• 제31권1호
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• pp.69-78
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• 2023

The purpose of this paper is to develop a scalable grey predictive controller with unavoidable random delays. Grey prediction is proposed to solve problems caused by incorrect parameter selection and to eliminate the effects of dynamic coupling between degrees of freedom (DOFs) in nonlinear systems. To address the stability problem, this study develops an improved gray-predictive adaptive fuzzy controller, which can not only solve the implementation problem by determining the stability of the system, but also apply the Linear Matrix Inequality (LMI) law to calculate Fuzzy change parameters. Fuzzy logic controllers manipulate robotic systems to improve their control performance. The stability is proved using Lyapunov stability theorem. In this article, the authors compare different controllers and the proposed predictive controller can significantly reduce the vibration of offshore platforms while keeping the required control force within an ideal small range. This paper presents a robust fuzzy control design that uses a model-based approach to overcome the effects of modeling errors. To guarantee the asymptotic stability of large nonlinear systems with multiple lags, the stability criterion is derived from the direct Lyapunov method. Based on this criterion and a distributed control system, a set of model-based fuzzy controllers is synthesized to stabilize large-scale nonlinear systems with multiple delays.

• 한국지능시스템학회논문지
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• 제11권6호
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• pp.477-486
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• 2001

본 논문은 TS(Takagi-Sugeno) 퍼지 모델로 근산 혹은 표현될 수 있는 비선형 시스템을 위한 TS 퍼지 제어기의 설계를 다룬다 본 논문에서 사용하는 주된 전략은, 안정도, 감쇠률 및 불확실성에 대한 강인성등의 설계요건을 만족시키는 리아푸노프 함수와 그에 대응하는 제어입력이 먼저결정된 후에 비용함수가 결정되는 역최적화 방법이다. 이러한 설계방법은, 설계요건뿐만 아니라 최적제어기 고유의 강인성까지 만족시키는 제어기를 제공하므로 매우 유용하다. 본 논문에서 확립되는 설계절차는 모두 선형행렬분등식을 푸는 형태로 이루어진다. 선형행렬부등식 문제는 내부점 방법에 의하여 주어진 허용 오차 이내에서 풀릴수 있으므로, 본 논문에서 제시하는 설계방법은 실용적인 특성을 갖는다. 제안된 설계 절차의 적용 방법은 설계 예제를 통하여 예시된다.