• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.477-481
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• 1993

The aim of this paper is to analyze via computer simulation the robust performance of TDF(Two Degree of Freedom) H.$_{\infty}$ controller for uncertain systems having parameter uncertainty. We apply the TDF H$_{\infty}$ controller to autopilot design. We evaluate the robust performance of the TDF H$_{\infty}$ controller for uncertain systems and present the guaranteed bound of robust performance via computer simulation.on.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.541-546
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• 2005

In this paper, the various uncertainties, which are generated in working of an optical disk drive, are discussed in details and the robust servo design considering the uncertainties are discussed. First, the classification of the uncertainties and the modeling process including that are treated. Then, the robust servo designs using QFT and $H_{\infty}$ theory are performed. Finally, the designed servo loops realized by DSP are applied to the real system. From these experiments, we proved that the robust servo design using QFT and $H_{\infty}$ have a good performance and a good robust stability when it compared with the conventional servo loop.

• 융합신호처리학회 학술대회논문집
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• 한국신호처리시스템학회 2000년도 하계종합학술대회논문집
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• pp.133-136
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• 2000

The objective of this paper is to present a method for designing robust positioning control systems of a flexible arm using $H_2/H_{\infty}$ and $\mu$ theory. We begin with a description of the flexible arm based on the model identification method and discuss the derivation of the model uncertainty. The validity of the obtained model is confirmed experimentally Next, a robust controller is designed based on the $H_2/H_{\infty}$ and $\mu$ theory by which we can improve robustness of the entire system. On this occasion, we also propose a general plant formation suitable to $H_2/H_{\infty}$ control. Finally, the effectiveness of the proposed design method is verified through experimentation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.936-938
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• 1996

The $H_{\infty}$ robust controller is designed for on-line adaptive control application by using polynomial approach. The $H_{\infty}$ robust controllers for adaptive system were designed first by Grimble. But they have a problem that two minimum costs can exist and did not minimize the conventional $H_{\infty}$ cost function which is the $H_{\infty}$ sum of weighted sensitivity and complementary sensitivity terms. In this paper, the two minimum costs problem can be avoided and the conventional $H_{\infty}$ cost function is minimized by employing the Youla parameterization and polynomial approach at the same time. In addition pole placement is possible without any relation with weighting function.

• 제어로봇시스템학회논문지
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• 제8권5호
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• pp.373-384
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• 2002

This paper presents a robust PID controller design technique using the concept of model matching method in the frequency domain. To design the robust PID controller satisfying disturbance attenuation and robust tracking property for a reference input, first an H$\infty$ controller satisfying given performance is designed using the H$\infty$ control method. And then, the parameters(proportional, integral, and derivative gains) of the robust PID controller are determined using the model matching at frequency domain. The proposed technique is applied to a position controller design of the web. The simulation results show that the proposed robust PID controller satisfies disturbance attenuation and tracking property.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.328-330
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• 1993

In this paper, we present a robust $H^{\infty}$ controller for a state delayed system with uncertainties. The unstructured and norm bounded uncertainties enter into both the state and the input matrix, where the matching condition of the uncertainties is not assumed. A robust stabilization condition and also a robust $H^{\infty}$ stabilization condition are suggested. The robust $H^{\infty}$ controller is obtained by solving a Riccati equation which is derived from the suggested robust $H^{\infty}$ stabilization condition.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2599-2601
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• 2000

A helicopter control problem has been researched with many control theory. Especially, study of the hovering flight attitude control of a helicopter has been brisked since 60s with multivariable control theory. In this paper, the modeling is interpreted through the 6-freedom equation. To getting a entire equation, species of parameters and charts are adapted. The $H_2/H_{\infty}$ controller is acquired by mixing the $H_2$ control theory and the $H_{\infty}$ control theory. The $H_2$ control theory is reasonable one to increase the performance of a plant, and the $H_{\infty}$ control theory secures the robust stability. The simulation shows that the helicopter system is being controlled while maintaining performance and robust stability against perturbation.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.401-405
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• 1996

A new method of nonlinear robust controller synthesis is introduced which is an extension of linear mixed $H_2/H_{\infty}$ control. This method guarantees robust stability fur hard nonlinearity and uncertainty of the plant. The method is applied to the control of a flexible link of robot with Coulomb friction. Simulation shows good performances with respect to the response and the robustness.

• 한국항공우주학회지
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• 제44권1호
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• pp.57-69
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• 2016

폐루프 기준으로 $H_{\infty}$ 제어기를 설계하는 알고리즘에는 3가지(2-ARE, mu-synthesis, LMI) 방법이 있다. 본 논문에서 3가지 $H_{\infty}$ 제어기 설계 알고리즘에 대한 기초 이론을 종합하고, Matlab$^{TM}$에 구현된 함수가 사용될 경우, 실무입장에서 가장 적절하다고 판단되는 $H_{\infty}$ 제어기 설계 알고리즘 제시를 위해 인공위성 자세 제어기 설계 후 결과를 비교 분석하였다: 2-ARE 방법과 LMI 방법은 robust stability, robust performance 및 control authority 측면에서 거의 유사하였으나, LMI 방법에 비해 2-ARE 방법이 weighting 함수설계에 더 민감하였고, mu-synthesis 방법은 다른 2가지 설계 방법에 비해 성능면에서 다소 떨어지고, control authority가 크게 나타났다. 따라서 인공위성 자세제어 설계를 위해 실무 관점에서 LMI 방법이 더 편리한 설계 알고리즘이라는 결론을 얻었다.

• Transactions on Control, Automation and Systems Engineering
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• 제2권1호
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• pp.31-39
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• 2000

We present a robust and reliable H$\infty$ state-feedback controller design for linear uncertain systems, which have norm-bounded time-varying uncertainty in the state matrix, and their prespecified sets of actuators are susceptible to failure. These controllers should guarantee robust stability of the systems and H$\infty$ norm bound against parameter uncertainty and/or actuator failures. Based on the linear matrix inequality (LMI) approach, two state-feedback controller design methods are constructed by formulating to a set of LMIs corresponding to all failure cases or a single LMI that covers all failure cases, with an additional costraint. Effectiveness and geometrical property of these controllers are validated via several numerical examples. Furthermore, the proposed LMI frameworks can be applied to multiobjective problems with additional constraints.