• 전기학회논문지
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• 제64권4호
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• pp.578-585
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• 2015

Electromagnetic levitation system(EMLS) is one of the well known nonlinear systems. Often, it is not easy to control an EMLS due to its high nonlinearity. In this paper, we first apply two linearization method(jacobian and input-output feedback linearization) to design two feedback controllers for an EMLS. Then, by observing the advantages of each controller, we design a switching control algorithm which engage two controllers depending on the position of the steel ball in order to achieve the improved performance over each controller. The validity of our switching control approach is verified via both simulation and actual experimental results.

• 전기학회논문지
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• 제59권2호
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• pp.411-416
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• 2010

In this paper, an integral variable structure static output feedback controller with an integral-augmented sliding surface is designed for the improved robust control of a uncertain system under unmatched system uncertainty and matched input matrix uncertainty and disturbance satisfying some conditions. To effectively remove the reaching phase problems, an output dependent integral augmented sliding surface is proposed. Its equivalent control and ideal sliding mode dynamics are obtained. The previous some limitations is overcome in this systematic design. A stabilizing control with the closed loop exponential stability is designed for all unmatched system matrix uncertainties and proved together with the existence condition of the sliding mode on S=0. To show the usefulness of the algorithm, a design example and computer simulations are presented.

• 전기학회논문지
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• 제65권12호
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• pp.2053-2056
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• 2016

In this paper, we propose an output feedback tracking control method for the wheeled mobile robots with kinematic disturbances. The kinematic disturbances should be compensated to avoid the performance degradation. Also, the unavailable velocity of the mobile robot should be estimated. These should be estimated together by designing the nonlinear observer. Based on these estimates, the output feedback controller can be designed. The stability of the mobile robot control systems using the proposed method is rigorously analyzed and the simulation results are also provided to validate the proposed method.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 춘계학술대회
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• pp.154-156
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• 2016

본 논문에서는 기존 위상고정루프의 아날로그 루프 필터 형태와 달리 전압제어발진기의 출력 신호로 동작하는 이산 루프 필터를 사용하여 크기는 작으면서 안정하게 동작하는 위상고정루프를 제안하였다. 샘플링과 부궤환 역할을 하는 스위치와 결합된 작은 크기의 커패시터로 하나의 칩으로 집적화가 가능한 위상고정루프는 1.8V 0.18um CMOS 공정을 이용하여 설계 하였다.

• 대한전기학회논문지
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• 제40권7호
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• pp.706-717
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• 1991

In order to remove the assumption of full state availability which is one of the major difficulties with the practical realization of variable structure control systems,a new switching function with a dynamic structure is proposed. And the control performances of the output feedback variable structure control systems with the dynamic switching function are evaluated through simulation studies. The proposed dynamic switching function is driven by small number of measured output and input variables while conventional static switching function requires full state information. Therefore, the proposition of the dynamic swiching function makes practical implementation of output feedback variable structure control scheme possible for the systems with unmeasurable state variables, high order systems and large scale systems that the conventional variable structure control schemes with static switching function cannot be applied. In the variable structure control systems with the dynamic switching function, desired control performance can be guaranteed by proper choice of design parameters such as poles of switching function dynamic equation and switching control gains even though small number of measured output and input variables are provided as shown in simulation resuls.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2002년도 추계학술대회 및 정기총회
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• pp.122-125
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• 2002

This paper proposes a stability condition in switched system and then, introduce design method of fuzzy-model-based controller which guarantees the stability. Takagi-Sugeno(75) fuzzy model is employed to design a switching-type fuzzy-model-based ,controller. Furthermore, it is proposed that the design method stabilizing continuous and discrete-time 75 fuzzy model respectively. Each controller in each subspace stabilize the subsystem respectively. In order to guarantee the stability of the global system, it is required to guarantee the stability condition in boundaries with subsystems. The condition which guarantees the stability in boundaries is presented in this paper. Inverted Pendulum system is employed to execute computer simulations. In this computer simulation, the performance of the proposed controller is verified by the control result.

• 전기학회논문지
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• 제60권3호
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• pp.625-631
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• 2011

This paper presents a discrete-time output feedback consensus algorithm for Multi-Agent Systems (MAS). Under the assumption that an agent is aware of the relative state information about its neighbors, a state feedback consensus algorithm is designed based on Linear Matrix Inequality (LMI) method. In general, however, it is possible to obtain its relative output information rather than the relative state information. To reconcile this problem, an Unknown Input Observer (UIO) is employed in this paper. To this end, first it is shown that the relative state information can be estimated using the UIO and the measured relative output information. Then a certainty-equivalence type output feedback consensus algorithm is proposed by combining the LMI-based state feedback consensus algorithm with the UIO. Finally, simulation results are given to illustrate that the proposed method successfully achieves the state consensus.

• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2004년도 추계학술대회
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• pp.145-147
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• 2004

LED(light emitting diode)는 처리속도, 전력소모, 수명 등에서 큰 장점이 있기 때문에 첨단조명의 광원으로 각광받고 있다. LED는 전원의 변동에 따라 광출력이 변동되므로 일정한 전압, 전류를 유지하는 기술이 필요하다. 따라서 본 논문에서는 LED 조명의 안정된 동작을 위한 전원장치로서 일정한 전압과 전류를 유지해주는 PWM(pulse width modulation) 궤환제어 방식의 부스트 컨버터를 제안하였다.

• 대한전기학회논문지
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• 제41권8호
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• pp.883-892
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• 1992

In order to remove the assumption of full state availability which is one of the major difficulties with the practical realization of variable structure control system (VSCS), an output feedback variable structure control scheme for multivariable systems is proposed. The proposed output feedback VSCS is composed of a switching surfaces with dynamic structure and a new output feedback control input that can be constructed by using conventional output feedback control input design methodologies. With the proposed scheme, the practical realization of VSCS for the systems with unmeasurable states and for high order systems that conventional schemes cannot be applied is possible. Simulation results show that proposed scheme is a viable method to achieve the desired control performance, for example, good transient response, robustness against process parameter variations and external disturbance without measuring all the state variables.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.996-998
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• 1996

This paper shows how the $H_{\infty}$ control problem of singular nonlinear systems via output feedback can be solved. The solution of the problem is shown to be related to the existence of solutions of a pair of Hamilton-Jacobi inequalities in n independent variables, which are associated with slate feedback and output injection design. Our approach yields to a set of sufficient conditions under an extra assumption. This conditions are in terms of a set of Hamilton-Jacobi Inequalities parameterized by adequately small parameters.