• 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.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.354-358
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• 1994

This study is concerned with H$_{\infty}$ control theory of nonlinear systems. Recently H$_{\infty}$ control theory has been developed to nonlinear systems, and especially nonlinear H$_{\infty}$ control theory based on the Hamilton-Jacobi inequality has been proposed. This corresponds to linear H$_{\infty}$ control theory based on the Riccati equation. In this paper, we apply it to a semi-active dynamic vibration absorber for multi-degree-of-freedom structure, and we design its state feedback controller via the Riccati equation. In the simulation, we show that it is effective for a vibration control.rol.

• 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.

• International Journal of Control, Automation, and Systems
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• 제4권6호
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• pp.689-696
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• 2006

This paper presents a new algorithm for the closed-loop $H_{\infty}$ composite control of weakly coupled bilinear systems with time-varying parameter uncertainties and exogenous disturbance using the successive Galerkin approximation(SGA). By using weak coupling theory, the robust $H_{\infty}$ control can be obtained from two reduced-order robust $H_{\infty}$ control problems in parallel. The $H_{\infty}$ control theory guarantees robust closed-loop performance but the resulting problem is difficult to solve for uncertain bilinear systems. In order to overcome the difficulties inherent in the $H_{\infty}$ control problem, two $H_{\infty}$ control laws are constructed in terms of the approximated solution to two independent Hamilton-Jacobi-Isaac equations using the SGA method. One of the purposes of this paper is to design a closed-loop parallel robust $H_{\infty}$ control law for the weakly coupled bilinear systems with parameter uncertainties using the SGA method. The other is to reduce the computational complexity when the SGA method is applied to the high order systems.

• 동력기계공학회지
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• 제7권1호
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• pp.60-67
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• 2003

This paper introduces basic study how to restrain the vibration of a four story shear structure. We have modeled a four story shear structure mathematically and have identified each parameters by experiment. We have gotten a reduced nominal model through modal analyzing method and the $H_{\infty}$ control theory is used in the control system design to get the robust controller. It's shown that the desirable performances is confirmed through the mathematical simulation. And a designed controller applying the $H_{\infty}$ control theory shows the good performance for the impulse disturbance through the simulation results. That is, the robustness of this control system is confirmed for the ability of disturbance rejection and modeling error.

• 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.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.93-99
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• 1998

Mathematical model can be obtained by physical law or engineering theory. However it is always incomplete expression of the real system. In active controls to suppress vibration due to earthquake or wind load, modeling errors can often cause the problems of instability and performance degradation. In this paper, robust optimal controller design method using H$\infty$ control theory is developed for the systems which have uncertain natural frequency and design constraints. Numerical results show that the proposed H$\infty$ controller can avoid the performance degradation due to several errors and has better performance than conventional LQR method.

• 동력기계공학회지
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• 제2권2호
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• pp.41-46
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• 1998

This paper presents the vibration control for the two degree-of-freedom which is a reduced model of multi-layer structure. This reduced model is designed for the first and second order resonance in the low frequency domain where the disturbance such as the earth quake has the large energy. And a designed controller using the LQ type $H_{\infty}$ control theory shows the good performance for the impulse disturbance through the experimental results and the simulation results respectively.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1994년도 Proceedings of the Korea Automatic Control Conference, 9th (KACC) ; Taejeon, Korea; 17-20 Oct. 1994
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• pp.512-517
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• 1994

The control system of a precise positioning mechanism with resonance and Coulomb friction has been designed using H$_{\infty}$ control theory, and the control performance has been verified by computer simulation and experimental analysis. The DGKF type H$_{\infty}$ control theory with scalar weighting factors was utilized for designing the control system. The followings have been confirmed from the present study: (1) The system with H$_{\infty}$ control presents better convergence and stability than the system with conventional control (PI-notch filter control). (2) The H$_{\infty}$ control system have good robustness properties for a wide range of operating conditions in the presence of external disturbances such as Coulomb friction and changing mechanical resonant frequency.ncy.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.391-395
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• 1996

This paper presents a robust force tracking control of a small-sized SMA gripper with two fingers using shape memory alloy(SMA) actuators. The mathematical governing equation of the proposed system is derived by Hamilton's principle and Lagrangian equation and then, the control system model is integrated with the first-order actuator dynamics. Uncertain system parameters such as time constant of the actuators are also included in the control model. A robust two degree of freedom(TDF) controller using H$_{\infty}$ control theory, which has inherent robustness to model uncertainties and external disturbances, is adopted to achieve end-point force tracking control of the two-finger gripper. Force tracking control performances for desired trajectories represented by sinusoidal and step functions are evaluated by undertaking both simulation and experimental works.