• 전기학회논문지
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• 제64권7호
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• pp.1096-1103
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• 2015

Electromagnetic levitation system(EMLS) is one of the well known nonlinear systems due to its high degree of nonlinearities. Moreover, when there are uncertain parameters in EMLS, it is not easy to have an accurate control of EMLS. In this paper, we first apply a standard input-output feedback linearzing controller to EMLS and investigate the possible control error caused by uncertain coil resistor. Then, as a remedy, we design and apply a robust controller using Lyapunov redesign technique to deal with this uncertain coil resistor in the system. The validity of our robust controller is verified via system analysis and experimental results.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.498-501
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• 1998

This paper deals with the design and evaluation of the robust controller for a synchronous generator excitation system to improve the steady state and transient stability. The nonlinear characteristics of the system is treated as model uncertainties, and then the robust control techniques are introduced into the power system stability design to take into account these uncertainties at the controller design stage. The performance of the designed controller is examined by extensive non-linear time domain simulation. It is shown that the performance of the robust controller is superior to that of the conventional PI controller.

• 한국통신학회논문지
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• 제28권11C호
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• pp.1062-1069
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• 2003

본 논문에서는 요구된 성능을 만족시키는 강인한 최적 PID 제어기 설계를 위한 새로운 루프 형성 기법을 제안 하고자 한다. 설계하고자 하는 PID 제어기의 영점들을 플랜트의 최대 극점에 근접하도록 가중치 요소 Q와 R을 선택하면 루프 형상이 고주파수 영역의 센서잡음 장벽으로부터 최대한 멀어지게 된다. 2차 시스템에 대하여 강인한 최적 PTD 제어기 설계가 가능한 새로운 루프 형성 기법은 LQR 방법에서 발전되었다.

• 제어로봇시스템학회논문지
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• 제9권1호
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• pp.82-89
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• 2003

A robust motion control method is proposed fur the point-to-point position control of a XY positioning system which consists of a base cart, elastic ben and moving mass. The horizontal motion controller consists of the feedforward controller to suppress the single mode vibration of the elastic beam and the feedback controller to get the high-accuracy positioning performance of the base cart. Input preshaping vibration suppression method based on system modeling with analytic frequency equation is proposed and integrated into the robust internal-loop compensator(RIC) to increase the robustness of the whole closed-loop system The vertical motion controller is proposed based on the dual RIC structure. Through experiments, it is shown that the proposed method can stabilize the system and suppress the vibration in the presence of uncertainties and disturbances.

• 제어로봇시스템학회논문지
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• 제16권1호
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• pp.77-82
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• 2010

An analytical method for robust design of the multi-loop proportional-integral (PI) controller is proposed for various types of multi-delay processes. On the basis of the direct synthesis and generalized IMC-PID approach, the analytical tuning rules of the multi-loop PI controller are firstly derived for achieving the desired closed-loop response, and the structured singular value synthesis is then utilized for the tradeoffs between the robust stability and performance by adjusting only one design parameter (i.e., the closed-loop time constant). To verify the superiority of the proposed method, the simulation studies have been conducted on a wide variety of multivariable processes. The multi-loop PI controller designed by the proposed method shows a fast, well-balanced and robust response with the minimum integral absolute error (IAE) in compared with other renowned methods.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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• pp.466-468
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• 1998

This paper designs a robust controller with improved stability of a system. Robust control theory has been developed by many researchers. The controller derived in that using robust control theory has an assumption that it will be exactly implementation. But, It is very hard because of truncation errors, D-A, A-D transformation, and finite resolution, etc. Such perturbations would make problems in the stability of the system. Recently, Keel's paper presents some examples which shows controllers based on the robust controller design method are very fragile on its own perturbation. In this paper, we try to improve the stability of the closed-loop system in which there exist perturbation in the plant as well as in the controller. The results shows that the stability is improved and the performance is still satisfied.

• KIEE International Transactions on Power Engineering
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• 제4A권3호
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• pp.109-114
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• 2004

In this paper, the H$\infty$ control method is applied in the control of SPFC and generators in order to obtain the robust stability performance of the power system. Moreover, a SPFC H$\infty$ controller based on loop shaping is designed to achieve first-rate tracking properties in addition to the robust stability. This robust control method is applied to a Ward and Hale 6-bus power system and the effects are analyzed. The MATLAB program is used for simulation of the robust controller.

• The Journal of the Acoustical Society of Korea
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• 제28권1E호
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• pp.16-22
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• 2009

In this paper, the new robust active noise controller was proposed to be applied for attenuating the noises when the nonlinear distortion in the secondary path exists. Through computer simulations as well as the analytical analysis, it could be shown that it is possible for both conventional LMS controller and proposed controller, to be applied for actively controlling the noises and linearizing the nonlinear distortion in the secondary path. Also, the simulations results demonstrated that the proposed controller may have faster convergence speed and better capability of controlling the noises and compensating the nonlinear distortion than the conventional LMS controller.

• 한국소음진동공학회논문집
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• 제25권5호
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• pp.361-368
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• 2015

This paper deals with a robust fine seek controller design problem with multiple constraints using a genetic algorithm. A robust $H\infty$ constraint is introduced to attenuate effectively velocity disturbance caused by the eccentric rotation of the disk. A weighting function is optimally selected based on the estimation of velocity disturbance and the estimated minimum velocity loop gain. A robust velocity loop constraint is considered to minimize the variances of the velocity loop gain and bandwidth against the uncertainties of fine actuator. Finally, a robust fine seek controller is obtained by solving a genetic algorithm with an LMI condition and an appropriate objective function. The proposed controller design method is applied to the fine seek control system of a DVD recording device and is evaluated through the experimental results.

• 전력전자학회논문지
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• 제16권4호
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• pp.317-325
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• 2011

본 논문에서는 단상 UPS 인버터의 강인한 전압제어기를 제안하고 설계한다. 제안된 전압제어기는 부하 변동에 대해서 강인 안정성과 강인 추종 성능을 얻기 위해 ${\mu}$-합성에 기초한 강인 제어 이론을 이용하여 설계되었다. 설계된 전압제어기의 강인 제어 성능은 ${\mu}$-해석을 통해 이론적으로 확인하였다. 그리고 단상 인버터에 대해 선형 부하와 비선형 부하로 시뮬레이션 및 실험을 수행하여 제안된 전압제어기가 안정된 전압제어 성능과 빠른 동특성을 가지는 향상된 제어성능을 제공하는 것을 확인하였다.