• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.997_998
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• 2009

Nowadays DC-DC converter has been used widely in electronic production. It has a high requirement in wide input voltage, load variations, stability, providing a fast transient response and the most important thing is that it can be applied easily and efficiently. However, it is not easy to be controlled because of nonlinear system. This study introduces a fuzzy linear control design method for nonlinear systems with optimal $H^{\infty}$ robustness performance. First, the Takagi and Sugeno fuzzy linear model is employed to approximate a nonlinear system. Next, based on the fuzzy linear model, a fuzzy controller is developed to stabilize the nonlinear system, and at the same time the effect of external disturbance on control performance is attenuated to a minimum level. Thus based on the fuzzy linear model, ��$H^{\infty}$ performance design can be achieved in nonlinear control systems. Linear matrix inequality (LMI) techniques are employed to solve this robust fuzzy control problem. PI control structure is used and the control gains are determined based on $H^{\infty}$ control.

• 제어로봇시스템학회논문지
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• 제20권11호
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• pp.1142-1146
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• 2014

This paper addresses on a $H_{\infty}$ sampled-data stabilization of a Takagi-Sugeno (T-S) fuzzy system. The sampled-data stabilization problem is formulated as a discrete-time stabilization one via a direct discrete-time design approach. It is shown that the sampled-data fuzzy control system is asymptotically stable whenever its exactly discretized model is asymptotically stable. Based on an exact discrete-time model, sufficient design conditions are derived in the format of linear matrix inequalities (LMIs). An example is provided to illustrate the effectiveness of the proposed methodology.

• 한국소음진동공학회논문집
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• 제14권12호
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• pp.1330-1337
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• 2004

In this study, the equations of motion of a rigid rotor supported by magnetic bearings are derived via Hamilton's principle, and transformed to a state-space form for control purpose. The optimal motion control of rotor magnetic bearing system based on the LQR(linear quadratic regulator) theory is addressed. New schemes related to the selection of the state weighting matrix Q and the control weighting matrix R involved in the quadratic functional to be minimized are proposed. And the robust control of the system with an LMI(linear matrix inequality) based H$_{\infty}$ theory is dealt with in this paper. Loop shapings of TFM (transfer function matrix) are used to increase the performance of control capability of the system. The control abilities of LQR and H$_{\infty}$ controller are compared by simulation and experimental tests and show that the capability of H$_{\infty}$ controller is superior to that of LQR.

• International Journal of Naval Architecture and Ocean Engineering
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• 제11권1호
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• pp.606-623
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• 2019

The path following problem of a ship sailing in restricted waters under wind effect is investigated based on Robust $H_{\infty}$ Guaranteed Cost Control (RHGCC). To design the controller, the ship maneuvering motion is modeled as a linear uncertain system with norm-bounded time-varying parametric uncertainty. To counteract the bank and wind effects, the integral of path error is augmented to the original system. Based on the extended linear uncertain system, sufficient conditions for existence of the RHGCC are given. To obtain an optimal robust $H_{\infty}$ guaranteed cost control law, a convex optimization problem with Linear Matrix Inequality (LMI) constraints is formulated, which minimizes the guaranteed cost of the close-loop system and mitigates the effect of external disturbance on the performance output. Numerical simulations have confirmed the effectiveness and robustness of the proposed control strategy for the path following goal of a ship sailing in restricted waters under wind effect.

• 동력기계공학회지
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• 제12권6호
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• pp.42-49
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• 2008

The most important job in the container terminal area is to handle the cargo effectively in the limited time. To achieve this object, many strategies have been introduced and applied to. If we consider the automated container terminal, it is necessary that the cargo handling equipments are equipped with more intelligent control systems. From the middle of the 1990's, an automated rail-mounted gantry crane(RMGC) and rubber-tired gantry crane(RTG) have been developed and widely used to handle containers in the yards. Recently, in these cranes, the many equipments like CCD cameras and sensors are mounted to cope with the automated terminal environment. In this paper, we try to support the development of more intelligent automated cranes which make the cargo handling be performed effectively in the yards. For this plant, the modelling, tracking control, anti-sway system design, skew motion suppressing and complicated motion control and suppressing problems must be considered. Especially, in this paper, the system modelling and tracking control approach are discussed. And, we design the tracking control system incorporating an observer based on the 2DOF servo system design approach to obtain the desired state informations. In the case of observer design, a weighted $H_{\infty}$ error bound approach for a state estimator is considered. Based on an algebraic Riccati equation(inequality) approach, a necessary and sufficient condition for the existence of a full-order estimator which satisfies the weighted $H_{\infty}$ error bound is introduced. Where, the condition for existence of the estimator is denoted by a Linear Matrix Inequality(LMI) which gives an optimized solution and observer gain. Based on this result, we apply it to the tracking control system design for the transfer crane.

• 전자공학회논문지SC
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• 제37권4호
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• pp.1-10
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• 2000

본 논문은 상태변수와 입력변수에 커멘슈레이트 시간지연을 갖는 선형시스템의 출력궤환 H/sub ∞/ 제어문제를 취급한다. 본 연구에서 제시한 출력궤환 제어기도 역시 제어기의 상태변수에 커멘슈레이트 시간지연항을 갖는다. 제어기는 컨벡스 최적화 기법을 사용하여 쉽게 풀 수 있는 선형행렬 부등식의 해를 이용하여 합성할수 있다. 제안하는 방법의 효용성을 예시하기 위하여 수치예를 제시한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.37.6-37
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• 2001

In this paper, a robust levitation controller for an attractive MAGLVE system is designed. The design of an H$\infty$ controller based on LMI method is proposed for the control of a simple magnetic levitation system. Attractive MAGLEV system is highly nonlinear and open-loop unstable, and has a very restricted equilibrium region, Also, this system has to tolerate various disturbances caused by propulsion. Thus a robust feedback controller is needed to control the system efficiently. We first formulate a mathematical model for the single magnet levitation system. Then we set up an H$\infty$ control problem as a mixed sensitivity problem where the augmented plant is constructed with frequency weighting function ...

• 한국정밀공학회지
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• 제15권9호
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• pp.33-42
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• 1998

If a ship diesel engine is operated by consolidated control with Controllable Pitch Propeller(CPP), the minimum fuel consumption is achieved together with the demanded ship speed. For this, it is necessary that the ship is operated on the ideal operating line which satisfies the minimum fuel consumption and that the pitch angle of CPP and throtle valve angle are controlled simultaneously. In this point of view, this paper presents a controller design method for a ship propulsion system with CPP based on the decoupling control theory. To do this, Linear Matrix Inequality(LMI) approach is introduced for the control system to satisfy the given $H_\infty$ control performance and robust stability in the presence of physical parameter perturbations. The validity and applicability of this approach are illustrated by simulation in the all operating ranges.

• 한국지능시스템학회논문지
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• 제20권5호
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• pp.617-623
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• 2010

본 논문에서는 차륜형 역진자에 적용되는 LMI 제어기 설계와 그 수치 시뮬레이션이 수행되었다. 차륜형 역진자는 2개의 평형점을 갖고 있는 역진자의 일종이다. 불안정한 평형점에 대하여 평형을 유지하기 위하여 차륜형 역진자는 지속적으로 제어되어야 한다. 경사면을 고려하여 차륜형 역진자의 동역학 방정식이 유도되었다. 경사면을 적극적으로 고려하여 차륜형 역진자를 안정화 시킬 수 있는 제어기를 구성하는데 선형행렬부등식 기법이 적용되었다. LMI 기반 제어기가 평면과 경사면에 대해서 유효함을 보이기 위해서 다양한 수치 시뮬레이션이 수행되었다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1725_1726
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• 2009

The purpose for this paper is to obtain the ��$H_{\infty}$ LMI with fuzzy PI controller for induction motor which is nonlinear system. The controller type is PI and the control gains are obtained based on $H_{\infty}$ control problem. The PI controller is considered a part of a plant and the problem is changed to get controller with static gains. The nonlinear system is approximated as several linear systems and combined by using fuzzy technique.