• Journal of KSNVE
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• v.3 no.4
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• pp.373-382
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• 1993

Active micro-vibration control of a structure, which simulates a stepper device, is performed using a pair of piezolectric actuators. The control aims at reducing the translational and rotational vibrations of the upper plate when the base is subject to seismic disturbance and the upper plate undergoes impulsive transient motion. Using the experimentally determined model, derivative control scheme is adopted so that the damping of the closed-loop system is effectively increased. It is found that the predicted control performance is in good agreement with the experimental results. Finally, the limit cycle phenomenon due to the controller voltage saturation is compared with the simulation.

• International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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• v.5 no.1
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• pp.46-52
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• 2002

A robust nonlinear observer, utilizing the sliding mode concept, is developed for the dynamic positioning of ships. The observer provides the estimates of linear velocities of the ship and bias from slowly varying environmental loads. It also filters out wave frequency motion to avoid wear of actuators and excessive fuel consumption. The main advantage of the proposed observer is in its robustness. Especially, the observer structure with a saturation function makes the proposed observer robust against neglected nonlinearties, disturbances and uncertainties. Since the mathematical model of DP ships is difficult to obtain and includes uncertainties and disturbances, it is very important for the observer to be robust. A nonlinear output feedback controller is derives based on the developed observer using the observer backstepping technique, and the global stability of the observer and control law is shown by Lyapunov stability theory.. A set of simulation was carried out to investigate the performance of the proposed observer for dynamic positioning of ships.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.05a
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• pp.293-297
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• 2002

본 연구는 파장 분할 다중화(WDM： Wavelength Division Multiplexing) 방식 전송 시스템 (Transmission System)에 사용되는 어븀 첨가 광섬유 증폭기(EDFA： Erbium-Doped Fiber Amplifier)의 이득 제어(Cain Control) 방법에 관한 것으로 어븀 첨가 광섬유에서 상호 이득 포화 (Cross Cain Saturation) 현상, 이득 비동질(Cain In-homogeneity) 특성, 그리고 어븀 이온의 밀도. 반전(Population Inversion)의 변화에 의해 출력되는 다 파장 광 신호들의 광세기가 각기 다르게 출력되는 현상을 고출력을 내도록 구성된 어븀 첨가 광섬유 증폭기와 고속 제어기를 구성하여 위 현상들을 억제하며 이득을 제어하기 위한 레이저 다이오드(Laser Diode : LD)의 제어전압 조사하고, 얻어 진 결과들을 토대로 이득 제어에 적합한 방법을 제시하고 제어기를 설계한다.

• Proceedings of the KIEE Conference
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• 1995.07b
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• pp.773-776
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• 1995

Sliding Mode Controller is largely used to control holy nonlinear system such as robot manipulator. This paper simulate the SCARA robot with sliding mode control algorithm and its applied form with saturation term to reduce chattering. In addition, hardware system using DSP board which operates with high speed is constructed.

• KIEE International Transaction on Systems and Control
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• v.12D no.1
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• pp.43-50
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• 2002

In the recent years neural networks have fulfilled the promise of providing model-free learning controllers for nonlinear systems; however, it is very difficult to guarantee the stability and robustness of neural network control systems. This paper proposes an adaptive neural network control for robot manipulators based on the radial basis function netwo.k (RBFN). The RBFN is a branch of the neural networks and is mathematically tractable. So we adopt the RBFN to approximate nonlinear robot dynamics. The RBFN generates control input signals based on the Lyapunov stability that is often used in the conventional control schemes. The saturation function is also chosen as an auxiliary controller to guarantee the stability and robustness of the control system under the external disturbances and modeling uncertainties.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2341-2344
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• 2001

In recent years the neural network known as a sort of the intelligent control strategy is used as a powerful tool for designing control system since it has learning ability. But it is difficult for neural network controllers to guarantee the stability of control systems. In this paper we try connecting a radial basis function network to an adaptive control strategy. Radial basis function networks are simpler and easier to handle than multilayer perceptrons. We use the radial basis function network to generate control input signals that are similar to the control inputs of adaptive control using linear reparameterization of the robot manipulator. We adopt the saturation function as an auxiliary controller. This paper also proves mathematically the stability of the control system under the existence of disturbances and modeling errors.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.2125-2133
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• 2018

To achieve high performance speed regulation, a robust adaptive speed controller is proposed for the permanent magnet synchronous motor (PMSM) subject to parameter uncertainties and input saturations in this paper. A nonlinear adaptive control is introduced to compensate the PMSM speed tracking errors due to uncertainties, disturbances and control input saturation constraints. By combining the adaptive control and the nonlinear robust control based on the interconnection and damping assignment (IDA) strategy, a new robust adaptive control is designed for speed regulation of PMSM. Stability and robustness of the closed-loop control system involved with the constrained control inputs rather than unconstrained control inputs are validated. Simulations for PMSM control in the presence of uncertainties and saturations nonlinearities show that the proposed approach is effective to regulate speed, and the average tracking error using the proposed approach is at least 32% smaller than the compared methods.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.38 no.11
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• pp.905-912
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• 1989

An adaptive control scheme is presented for uncertain systems whose uncertainties are upper-bounded by a linear combination of unknown constants and known continuous functions. The state of the closed-loop system is proven to be ultimately bounded. The proposed method modifies the method of Corless and Leitmann in the following two respects. First, the linear region of the saturation function in controller is fixed. Second, the intergration from in parameter estimator is replaced by a low pass filter form. These modifications prevent performance degradation and destabilization of the control system more effectively. The norm of the system states can be made sufficiently small by an appropriate choice of design parameters in the control law. The applicability of the proposed scheme is demonstrated in the position control of a simple pendulum via simulation.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.12
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• pp.1218-1229
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• 1991

The time optimal position control design can be repeatedly taken from the initial state of a dynamic system to a desired one as fast as possible in the industrial drives. In this case, an induction machine parameters will vary due to temperature, frequency, and saturation effects. In particular, the rotor resistance changes critically with temperature and frequency. These changes affect the command values of the stator current components and slip speed. There is a mismatch between the commanded variables and actual ones of the induction motor drive, and this situation leads to coupling of the vector controller from the plant, i.e. the induction motor . Consequences of such a coupling include the initiation of oscillations of the rotor flux and unsuitable switching of electromagnetic torque for the induction motor servo drive. Therefore, this paper describes a rotor resistance parameter compensating method for the induction motor, And the validity of the proposed design method is confirmed by simulation studies and experiment results.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.211-213
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• 2007

The electrical parameters are used to calculate gains in the current regulator as well as to determine the reference currents of speed controller in various control strategies of Synchronous Reluctance Motors (SynRMs). Many methods of measuring or estimating the electrical parameters of SynRM have been proposed by other authors. But almost papers only measure or estimate in the limited conditions without fully considering the effects of inverter, connecting wire and magnetic saturation. The parameter results are usually different from the real system parameters. The drive performance, therefore, can not be good if using inaccurate parameters. In this paper, several methods used to measure the electrical parameters are introduced. The first method is LCR meter. And then, a method determining inductances by measuring AC current and voltage from AC power supply is presented. A new method with high reliability is proposed to measure the electrical parameters of SynRM. The experiment results verify the effectiveness of the new proposed method.