• Journal of Advanced Marine Engineering and Technology
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• v.36 no.1
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• pp.126-132
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• 2012

This paper suggests a design method of the model-following H${\infty}$ control system having robust performance. This H${\infty}$ control system is designed by applying genetic algorithm(GA) with reference model to the optimal determination of weighting functions and design parameter ${\gamma}$ that are given by Glover-Doyle algorithm which can design H${\infty}$ controller in the state space. These weighting functions and design parameter ${\gamma}$ are optimized simultaneously in the search domain guaranteeing the robust performance of closed-loop system. The effectiveness of this H${\infty}$ control system is verified by applying to the boiler-turbine control system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.5
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• pp.198-202
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• 2004

This thesis proposes a robust controller introducing the H$_{\infty}$ control theory, one of the robust control theories that can obtain desired control performance while ensuring robustness for the uncertainty and disturbance contained in the power system. The performance of the designed controller is examined by extensive non-linear time domain simulation. Results show that the proposed H$_{\infty}$ controller is superior to that of the conventional controller.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.6
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• pp.820-828
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• 2011

Energy saving is one of the most important factors for profits in marine transportation. In order to reduce the specific fuel oil consumption, the ship's propulsion efficiency must be increased as much as possible. The propulsion efficiency depends upon a combination of propulsion engine and propeller that has better efficiency as lower rotational speed. As the engine has lower speed the variation of rotational torque become larger because of the longer delay time in fuel oil injection process. In this study, robust control theory is applied to the design of engine speed controllers which are sub-optimal $H_{\infty}$ controller, $H_{\infty}$ loop-shaping controller and ${\mu}$-synthesis controller considering robust stability and robust performance. And the validity of these three controllers is investigated through the results of computer simulation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.316-321
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• 2007

[ $H{\infty}$ ] controller, which shows robustness for disturbances and noises, can not be used in the case of uncertain system parameters. Even if the $H{\infty}$ controller can be designed for the parameter uncertain system, its performance can be deteriorated. Therefore, in this paper, the robustness of $H{\infty}$ controller is improved by using the SMC(Sliding Mode Control). The LMI based $H{\infty}$ controller is designed first and then SMC controller is added.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.3
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• pp.41-49
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• 1999

In this paper, we design a controller using the $\mu$-synthesis method and apply it for the spring-mass system with noncollocated sensors and actuators. We assume that the values of the spring stiffness and load mass of the plant are uncertain. The plant is modeled with parametric uncertainty by using the state space equation, especially the descriptor form. The $H_\infty$ controller designed by the $\mu$-synthesis method is compared with the standard $H_\infty$ controller To compare performances of two $H_\infty$ controllers, it is assumed that both controllers were designed with same weighting functions except that the $\mu$-synthesis controller has structured uncertainties. By compared with the standard $H_\infty$ controller, we show that the designed controller has satisfactory robust performance as well as robust stability by simulations and experiments.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.39 no.2
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• pp.95-103
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• 2002

This paper deals with the H$_{\infty}$ control problems for discrete-time linear systems with time-varying delays in states. The existence condition and the design method of the H$_{\infty}$ state feedback controller are given. In this paper, the H$_{\infty}$ control law is assumed to be a memoryless state feedback, and the upper-bound of time-varying delay and S-procedure are used. Through some changes of variables and Schur complement, the obtained sufficient condition can be rewritten as an LMI(linear matrix inequality) form in terms of all variables.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.89-98
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• 2015

This paper provides a robust and non-fragile $H_{\infty}$ controller design algorithm for time-delayed systems with randomly occurring polytopic uncertainties and disturbances. First, we design time-delayed system considering randomly occurring uncertainties and disturbances. Next, The sufficient condition for the existence of robust and non-fragile $H_{\infty}$ controller is presented by LMI(linear matrix inequality) using Lyapunov stability analysis and $H_{\infty}$ performance measure. Since the obtained condition can be expressed as a PLMI(parameterized linear matrix inequality) by changes of variables and Schur complement, all solutions including controller gain, degrees of controller satisfying non-fragility, $H_{\infty}$ norm bound ${\gamma}$ can be calculated simultaneously. Finally, numerical examples are given to illustrate the performance and the effectiveness of the proposed robust and non-fragile $H_{\infty}$ controller compared with the deterministic uncertainty model even though there exists randomly occurring uncertainties, disturbances and time delays.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.4
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• pp.29-37
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• 2004

This paper provides a reliable H$_{\infty}$ state feedback controller design method for delayed singular systems with actuator failures occurred within the prescribed subset. The sufficient condition for the existence of a reliable H$_{\infty}$ controller and the controller design method are presented by linear matrix inequality(LMI), singular value decomposition, Schur complements, and changes of variables. The proposed controller guarantees not only asymptotic stability but also H$_{\infty}$ norm bound in spite of existence of actuator failures. Since the obtained sufficient condition can be expressed as an LMI fen all variables can be calculated simultaneously. Moreover, the controller design method can be extended to the problem of robust reliable H$_{\infty}$ controller design method for singular systems with parameter uncertainties, time-varying delay, and actuator failures. A numerical example is given to illustrate the validity of the result.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.3
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• pp.13-18
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• 2005

This paper presents a design of a multi-objective $H_2/H_{\infty}$ controller of an inverted pendulum with polytopic model by the stabilizing regulator and tracking performances. Multi-objective controllers are designed for polytopic models by the LMI design technique with convex algorithms. It is observed that the inverted pendulum controlled by any controller designed for each polytopic model is stably restored to the vertical angle position for initial values of larger tilt angles.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.888-891
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• 1996

The objective of a mixed H$_{2}$/H$_{\infty}$ controller of active suspension system is to achieve not only the general performance improvement(H$_{2}$) but also the worst case disturbance rejection(H$_{\infty}$). In this paper, a mixed H$_{2}$/H$_{\infty}$ controller for an active suspension system, comparing the performance with that of an H$_{2}$ controller and of an H$_{\infty}$ controller.ler.EX> controller.