• 대한전기학회논문지
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• 제37권12호
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• pp.884-893
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• 1988

Adaptive controllers for linear unknown coefficient system, that is corrupted by disturbance, are designed by parameter adaptation model reference adaptive control(MRAC). This design is stemmed from the Lyapunov direct method. To reduce the model following error and to improve the convergence rate of the design, an indirect-suboptimal control law is derived. Proper compensation for the effects of time-varying coefficients and plant disturbance are suggested. In the design procedure no complete identification of unknown coefficients are required.

• 대한전기학회논문지
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• 제37권10호
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• pp.733-739
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• 1988

Adaptive controllers for linear system whose nominal values of coefficients only are known, that is corrupted by disturbance, are designed by signal synthesis model reference adaptive control (MRAC). This design is stemmed from the Lyapunov direct method. To reduce the model following error and to improve the conrergence rate of the design, an indirect suboptimal control law is de rived using the Hamilton Jacobi Beellman equation. Proper compensaton for the effects of time varying coefficients and plant disturbance are suggested. In the design procedure no complete identification of unknown coefficients are required.

• 한국정밀공학회지
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• 제21권1호
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• pp.124-132
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• 2004

A hydraulic system is difficult to keep the performance due to non-linearity, load pressure which changes according to working condition and system parameter variation, the requirement of control algorithm has been risen in order to satisfy them. An adaptive control is a control method which is suggested to achieve a control object though plant characteristics change. In spite of the case that plant characteristics and the degree of variation are difficult to grasp, adaptive control can keep the characteristics of closed-loop system regularly. In this study GMVAC(generalized minimum variance adaptive control) combined with output error feedback is proposed in order to solve problems of non-minimum phase, vibration and overshoot in initial response of the plant. The control performance according to the variation of characteristics of the plant is evaluated by changing the supply pressure only.

• Journal of Advanced Marine Engineering and Technology
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• 제19권3호
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• pp.77-83
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• 1995

Recently, in the field of industrial servo-systems, several methods have been proposed for tracking the reference input fastly and finely without overshoot. These methods, however, are established under hypothesis that structure and parameters of the plant are known accurately and they are time invariant. In practice, it is difficult to obtain the values of plant's parameters accurately and usually plants change with time and operation conditions. In this paper a method to construct the nominal model tracking adaptive control system is proposed. The system is composed of the nomial model which produces a ideal response and the model tracking system with the fuzzy adaptive controller. If the actual plant is equal to the controlled object in the nominal model, the output of the plant is the same as that of the nominal model and the fuzzy adaptive controller becomes idle. However, when the plant changes, the fuzzy adaptive controller of the tracking system operates in order for the output of the plant to track the ideal response. Through the computer simulations under various conditions, it is confirmed that the proposed model tracking system is very effective.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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• pp.321-325
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• 1988

The objective of this study is to develop a microcomputer-based adaptive controller for an electro hydraulic velocity control system subjected to the variation of system parameters. The step response performance of the system with the adaptive controller is investigated for the variation of the external load torque, the moment of inertia and the reference inputs, and compared with that obtained by PID controller whose gains are constant. The experimental results show that this proposed model reference adaptive controller is robust to the variation of system parameters and yield much better control performance compared with the conventionel PID controller.

• Journal of Mechanical Science and Technology
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• 제15권10호
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• pp.1356-1368
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• 2001

In this paper, the model reference adaptive control (MRAC) of a flexible structure is investigated. Any mechanically flexible structure is inherently distributed parameter in nature, so that its dynamics are described by a partial, rather than ordinary, differential equation. The MRAC problem is formulated as an initial value problem of coupled partial and ordinary differential equations in weak form. The well-posedness of the initial value problem is proved. The control law is derived by using the Lyapunov redesign method on an infinite dimensional filbert space. Uniform asymptotic stability of the closed loop system is established, and asymptotic tracking, i. e., convergence of the state-error to zero, is obtained. With an additional persistence of excitation condition for the reference model, parameter-error convergence to zero is also shown. Numerical simulations are provided.

• 한국산학기술학회논문지
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• 제17권2호
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• pp.697-702
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• 2016

매입형 영구자석 동기전동기의 원활한 제어를 위해서는 전동기의 상수인 고정자 저항이나 각종 인덕턴스의 값, 그리고 쇄교 자속의 값 등을 정확하게 알아야 한다. 그러나 이러한 상수들은 전동기 운행에 따른 전동기 온도의 상승이나 각 작동점 등의 변화에 따라 계속적으로 변하기 때문에 이들의 값을 정확하게 추정하는 것은 매우 어렵다. 이러한 문제점을 극복하기 위해서 실시간으로 상수의 값을 추정하는 기법이 필요한데 본 논문에서는 MRAS(Model Reference Adaptive System) 기법을 이용한 상수의 추정 및 적응제어 기법을 제시한다. 시스템의 관계식이 이들 상수에 대해 비선형으로 구성되어 있어 일반적인 제어기법을 적용하는데 문제가 있어 일부 논문에서는 상수의 일부를 안다고 가정하였지만 본 논문에서는 이러한 가정 없이 모든 상수를 추정하는 제어기법을 제시하고 적응제어 기법의 수렴성을 입증하였다. 제시하는 알고리즘의 우수성은 시뮬레이션을 통해 입증하도록 한다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.418-423
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• 1992

In this paper, a model reference adaptive control algorithm is applied to the design of the normal acceleration controller for missiles with nonminimum-phase characteristics. The method used in this paper is due to Ohkubo. In this scheme, a feedforward compensator is designed first so that the extended system becomes minimum-phase and after that an adaptive control algorithms is designed for the extended system. The feedforwrd compensator is obtained by solving the robust stabilization problem. It is shown that the performance of the designed controller is satisfied via computer simulation.

• 전력전자학회논문지
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• 제7권5호
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• pp.413-418
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• 2002

본 연구는 관성의 변화에 견실한 피드포워드 적응 위치제어기를 제안한다. 제안된 피드포워드 적응 위치제어기는 PI 위치제어기에 피드포워드와 기준모델 적응제어기를 추가한 구조를 가진다. 제어기의 특징은 과도상태에서 적응제어기가 위치오차와 기준모델의 속도 정보를 이용하여 피드포워드 이득을 조정한다. 이것은 과도응답 특성을 향상시키고, 정상상태의 수렴 시간을 개선시킨다. 위치 오차에 속도의 정보를 받아들여 기존의 Pl 위치제어 및 기준모델 적응제어에 비하여 속응성이 우수하다. 그리고, 적응제어기에 규준화 함수를 사용하여 입력크기에 대해 출력신호가 일정한 응답특성을 가지도록 하였다. 시뮬레이션을 통하여 제안된 피드포워드 적응 위치제어기 동작의 타당성을 보였다.

• 대한전기학회논문지
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• 제32권6호
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• pp.219-224
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• 1983

The problem of model reference adaptive control for the discrete time system is considered and the global stability of the overall system is shown. It extends the results of Kreisselmeier's to more general reference models and the method presented here makes the output error and controller parameter error converge to zero. The scheme presented in this paper is simulated and the simulation gives the expected results.