• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1133-1135
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• 2000

In the industrial motor drive system which is composed of a motor and load connected with a flexible shaft, a torsional vibration is often generated because of the elastic elements in torque transmission. To solve this problem, the two-degrees-of-freedom $H_{\infty}$ controller was designed. But it is difficult to realize that controller. In this paper, a new partial state feedback $H_{\infty}$ controller with resonance ratio control is proposed. Proposed controller has simple structure but satisfies the attenuation of disturbances and vibrations.

• ICROS
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• v.1 no.2
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• pp.21-29
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• 1995

이 글에서는 H/sub .inf./ 설계법의 장단점에 대해서 알아보았다. H/sub .inf./ 제어기법은 이론적인 연구와 함께 산업응용에 관한 연구도 활발하여, 자동차 제어, 항공우주 제어(고성능 헬리콥터의 비행제어, 비행체의 핏치축 제어, 우주구조물체의 제어), 공정제어(발전소에서의 핵반응로 제어), 및 기계제어 등에 광범위하게 응용되고 있다. H/sub .inf./ 제어기법은 여타의 다른 제어기 설계기법에 비해 많은 수학적 지식을 필요로 하고 제어이론 및 설계과정이 복잡한 것으로 인식돼 우리나라에서는 그다지 많은 관심을 끌지 못하고 있는 것 같다. 그러나, 응용사례에서 알 수 있는 것처럼 그 응용대상이 광범위하고, 또한 고성능의 제어목적을 달성하기 위해 필요한 제어기법으로 자리잡아가고 있으므로 보다 더한 관심을 기울일 필요가 있을 것으로 사료된다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.2
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• pp.500-510
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• 1996

This paper presents a new prototype of an engine mount for a passenger vehicle featuring ER(elector-rheological) fluids and piezoactuators. Conventional rubber mounts and various types of passive or semi-active hydraulic engine mounts have their own functional aims on the limited frequency band in the board engine operating frequency range. However, the proposed engine mount covers all frequency range of the engine operation. A mathematical model of the proposed engine mount is derived using the bond graph method which is inherently domain, the ER fluid is activated upon imposing electric field for vibration isolation while the piezoactuator. Computer control electric fluid for the ER fluid H.inf. cotrol technique is adopted for the piezoactuator. Computer simulation is undertaken in order to demonstrate isolation efficiency of the engine mount over wide operating frequency range.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.1973-1975
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• 2001

In this paper, we consider the problem of robust peak-to-peak controller design of linear system. The goal is to design a controller which minimizes the maximum peak value of the measured output subjects to the peak bounded disturbance. The control is obtained by checking the feasibility of the derived matrix inequalities. Finally, we shows the usefulness of our result comparing to $H_{\infty}$ and $H_{2}$ control by an example.

• Journal of Electrical Engineering and information Science
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• v.2 no.5
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• pp.27-32
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• 1997

This paper presents an H\ulcorner controller design method for linear time-invariant systems with delayed state and control. Using the second method of Lyapunov, the stability for delayed systems is discussed. For delayed systems, we derive a sufficient condition of the bounded real lemma(BRL) which is similar to GBRL for nondelayed systems. And the sufficent conditions for the existence of an H\ulcorner controller of any order are given in terms of three linear matrix inequalities(LMIs). Further, we briefly explain how to construct such controllers from the positive definite solutions of their LMIs and gie a simple example to illustrate the validity of the proposed design procedure.

• Journal of Power Electronics
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• v.18 no.1
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• pp.251-265
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• 2018

To enable a master-slave control independent microgrid system (MSCIMGS) to supply electricity continuously, the microgrid inverter should perform mode transfer between grid-connected and islanding operations. Transient oscillations should be reduced during transfer to effectively conduct a seamless mode transfer. This study uses a typical MSCIMGS as an example and improves the mode transfer strategy in three aspects: (1) adopts a status-tracking algorithm to improve the switching strategy of the outer loop, (2) uses the voltage magnitude and phase pre-synchronization algorithm to reduce transient shock at the time of grid connection, and (3) applies the hybrid-sensitivity $H_{\infty}$ robust controller instead of the current inner loop to improve the robustness of the controller. Simulations and experiments show that the proposed strategy is more practical than the traditional proportional-derivative control mode transfer and effective in reducing voltage and current oscillations during the transfer period.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.100.2-100
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• 2001

In this paper, we presented a switching-based control algorithm for improving the speed of response on temperature control of an extruder. We proposed a switching actuating value method in a temperature control of extruder and showed the effect of H$\infty$ control and PID control. Recently, the memoryless feedback control had proposed, which was not only the real time integration element, but also the memory elements. We examined the application of a switching actuating value method to a memoryless feedback, in a unit barrel temperature control of an extruder.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.513-522
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• 2006

This paper considers a robust output feedback $H\infty$ controller design method for singular systems with time-varying delay in state and parameter uncertainty in system matrix by an LMI approach and observer based technique, which can be solved efficiently by convex optimization. The sufficient condition for the existence of controller and the controller design method are presented by strict LMI(linear matrix inequality) approach. Since the obtained condition can be expressed as an LMI form, all variables including feedback gain and observer gain can be calculated simultaneously by Schur complement and changes of variables.

• Journal of Electrical Engineering and information Science
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• v.3 no.3
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• pp.306-315
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• 1998

In this paper, a unified approach to the H\ulcorner controller design is proposed under the $\delta$-form for both continuous and discrete systems. Most of important basic concepts of H\ulcorner control, such as inner, co-inner, GCARE and GFARE, are reformulated by the unified form. The NLCF(Normalized left Comprime Factor) plant description has been reviewed in the $\delta$-form, and some corresponding results are proposed. And the unified H\ulcorner controller is designed which is based on the McFarlane and Glover{1]. The state-space parameterization for all suboptimal controllers is given under the NLCF model which may not be strictly proper, and the central controller is derived by using the solution to Hankel norm approximation problem[2]. The unified controller is applied to the industrial boiler control problem to exemplify the performance of the controller.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.442-449
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• 2003

This paper presents a robust hybrid control system for seismic response control of a cable-stayed bridge. Because multiple control devices are operating, a hybrid control system could alleviate some of restirctions and limitations that exist when each system is acting alone. A LQG algorithm with on-off control scheme, H$_2$ and H$_{\infty}$ control algorithms with various frequency weighting filters are used to improve the controller robustness of the active control part in the hybrid control system. The numerital simulation results show that control performances of robust hybrid control systems are similar to those of the hybrid control system with LQG algorithm. Furthermore, it is verified that robust hybrid control systems are more robust than the hybrid control system with LQG algorithm and there are no signs of instabilities in the $\pm$5％ stiffness matrix perturbed system. Therefore, the proposed hybrid control system have a good robustness for stiffness matrix perturbation without loss of control effectiveness.