• 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.

• 제어로봇시스템학회논문지
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• 제5권3호
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• pp.363-369
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• 1999

In this paper, we design the robust $H_{\infty}$ controller for water level control of steam generator using a mixed $H_{\infty}$ optimization with model-matching method. Firstly we choose the desired model which has good disturbance rejection performance. Secondly we design a stabilizing controller to keep the model-matching error small and also provide sufficiently large stability margin against additive perturbations of the nominal plant. Simulation results show that proposed robust $H_{\infty}$ controller at specific power operation has satisfactory performances against the variations of load power, steam flow rate, primary circuit coolant temperature, and feedwater temperature. It can be also observed that the proposed robust $H_{\infty}$ controller exhibits better robust stability than conventional PI controller.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 D
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• pp.2137-2139
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• 2003

본 논문에서는 초고속 비동기전송(ATM)망에서의 체증 문제를 풀기위해 $H_{\infty}$ 필터 사용을 제안한다. 많은 제어기들에 대한 초기 연구들은 가용 비트율이 망 체증이 제거될 수 있도록 버퍼에서의 원하는 셀들의 큐의 길이를 원하는 값 범위내에서 성공적으로 조절될 수 있음을 보이고 있다. 본 논문에서는 망의 노이즈를 가우시안 랜덤 열로 근사화하는 ATM망에 대하여 현대 제어 기법인 $H_{\infty}$ 필터를 적용한다. 따라서 제안한 $H_{\infty}$ 필터는 망의 외란으로 밭생하는 망의 출력의 영향을 미리 주어지는 $H_{\infty}$ 노옴값 이내로 유지시켜준다. 따라서 미리 주어지는 $H_{\infty}$ 노옴값이 작다면 제안한 $H_{\infty}$ 필터는 외란에 강인한 성능을 보여줄 수 있다. $H_{\infty}$ 필터 이득은 대수적인 리카티 방정식의 해로 구해진다.

• 한국정밀공학회지
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• 제14권2호
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• pp.160-168
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• 1997

A $H_{\infty}$self-tuning control scheme for the tip position of a flexible link robot handling unknown loads is presented here. The scheme essentially comprises a recursive least-squares identification algorithm and $H_{\infty}$self-tunning controller. The $H_{\infty}$control low is designed to be robust to uncertain parameters and the self-tunning action provides adaption to unknown parameters. Through numerical study, the performance comparison of the $H_{\infty}$self-tuning controller with a constant gain $H_{\infty}$controller as well as a LQG self-tuning controller clearly shows its superior ability in handling load changes in quiescent states.nt states.

• 융합신호처리학회논문지
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• 제2권1호
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• pp.101-107
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• 2001

본 연구는 유연한 빔의 위치를 제어하기 위한 강인한 제어기 설계를 위한 하나의 방법으로서 혼합 $H_2/H_{\infty}$과 $\mu$이론을 이용한 하나의 방법을 제시하고 있다. 먼저 제어기의 설계를 위한 유연한 빔의 수식모델을 얻기 위해 해석적인 방법과 실험을 통한 방법을 적용하였다. 이 결과로서 강인한 제어기의 설계를 위해 필요한 불확실성의 영역에 대한 정확한 정보를 얻을 수 있다. 다음, 혼합 $H_2/H_{\infty}$ 이론을 상기모델에 적용하여 강인한 제어기를 설계하고, 여기에 $\mu$이론을 적용하여 일반적으로 혼합 $H_{\infty}$ 제어기가 가질 수 있는 보수성을 완화시킨다 마지막으로 Simulation과 실험을 통하여 설계된 제어기의 유효성을 보인다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.322-322
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• 2000

This paper shows an application of H$_{\infty}$ control design for a magnetic suspension system which has strongly nonlinearity and parameter perturbation. The control design is evaluated by numerical simulations and experiments.

• 제어로봇시스템학회논문지
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• 제6권5호
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• pp.345-355
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• 2000

In this paper, the depth controller of an underwater vehicle based on an $H_\infty$ servo control is designed for the depth keeping of the underwater vehicle under wave disturbances. The depth controller is designed in the form of the $H_\infty$ servo controller, which has robust tracking property, and an $H_\infty$ servo problem is considered for the $H_\infty$ servo controller design. In order to solve the $H_\infty$ servo problem for the underwater vehicle, this problem is modified as an $H_\infty$ control problem for the generalized plant that includes a reference input mode, and a suboptimal solution that satisfies a given performance criteria is calculated with the LMI (Linear Matrix Inequality) approach. The $H_\infty$ servo controller is designed to have robust stability about the perturbation of the parameters of the underwater vehicle and the robust tracking property of the underwater vehicle depth under wave force and moment disturbances. The performance, robustness about the uncertainties, and depth tracking property, of the designed depth controller is evaluated by computer simulation, and finally these simulation results show the usefulness and applicability of the proposed $H_\infty$ depth control system.

• Journal of Advanced Marine Engineering and Technology
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• 제36권1호
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• pp.126-132
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• 2012

본 연구에서는 강인한 성능을 가지는 모델추종형 H${\infty}$ 제어기의 설계법을 제시한다. 이를 위해 강인한 성능을 보장하는 해집단내에서 기준모델의 출력을 최적으로 추종하도록 유전 알고리즘을 사용하여 가중치 함수와 설계 파라미터 ${\gamma}$를 동시에 최적화한다. 설계된 H${\infty}$ 제어기는 강인한 성능에 관한 필요충분조건식을 만족함은 물론 설계사양에 따른 만족스러운 응답특성을 가진다. 제시된 방법을 보일러-터빈 제어 시스템에 적용하여 그 유용성을 확인한다.

• 제어로봇시스템학회논문지
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• 제6권7호
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• pp.529-536
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• 2000

A robust controller to attenuate the various disturbances of tandem cold mills (TCM) is synthesized by measurement-feedback $H_{\infty}$ control techniques which can reflect the input direction of disturbances and the knowledge of entry thickness variation (disturbance) is synthesized by discrete-time measurement-feedback $H_{\infty}$ control theory. It is demonstrated that the $H_{\infty}$ preview control gain can be easily obtained by the seperation principle of the control and estimation problems in $H_{\infty}$ control. Finally the effectiveness of the proposed control method for TCM is evaluated by the computer simulation and compared to the other control methods which have been previously studied.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.560-564
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• 1996

A mixed H$^{2}$/$H^{\infty}$ controller design method for linear systems with time delay in all variables and parameter uncertainties in all system matrices is proposed. Robust $H^{\infty}$ performance and H$^{2}$ performance condition that accounts for model-matching of closed loop system and disturbance rejection is also derived. With expressing uncertain system with linear fractional transformation form, we transform the robust stability and performance problem to the H$^{2}$/$H^{\infty}$ optimization problem and design a mixed H$^{2}$/$H^{\infty}$ controller. Using the proposed method, mixed H$^{2}$/$H^{\infty}$ controller for underwater vehicle with time delay and parameter variations are designed. Simulations of a design example with hydrodynamic parameter variations and disturbance are presented to demonstrate the achievement of good robust performance.t performance.ance.