• Journal of the Korea Institute of Military Science and Technology
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• v.26 no.1
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• pp.72-82
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• 2023

The EOTS(Electro Optical Tracking System) must have stabilization performance to provide high-quality images under disturbance environment. In this paper, we present a controller that can minimize the LOS error and has a simple structure. Hence, to evaluate the performance of this controller, analysis in the frequency domain and LOS error measurement are performed. In order to measure the LOS error without a 'rate table' that requires a lot of facility investment, we propose a design method for disturbance model that considers the operating environment of the EOTS. Finally, the performance of the stabilization algorithm is evaluated by the proposed disturbance model.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.1
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• pp.89-93
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• 2000

Robust control for DC motor is needed according to the highest precision of industrial automation. However, when a motor control system has an effect of load disturbance, it is very difficult to guarantee the robustness of control system. Generally, it is known that sliding mode controller has robustness. But, after it is assumed that we known the disturbance uncertainty, sliding mode controller is designed. Thereafter, if we are not known th disturbance uncertainty then controller design is difficult. As a method solving this problem, in this paper, Expert sliding mode control method for motor control system is presented.The proposed controller can eliminate load disturbance effectively. The effectiveness of the control scheme is verified by simulation results.

• Journal of Power Electronics
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• v.16 no.4
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• pp.1578-1586
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• 2016

A power quality improvement scheme for grid connected inverters, even in the presence of the disturbances in grid voltages due to harmonic distortions and three-phase imbalance, is presented for distributed generation (DG) power systems. The control objective is to force the inverter currents to follow their references with robustness even under external disturbances in grid voltages. The proposed scheme is realized by a disturbance observer (DOB) based current control scheme. Since the uncertainty in a system can be effectively canceled out using an estimated disturbance by the DOB, the resultant system behaves like a closed-loop system consisting of a disturbance-free nominal model. For experimental verification, a 2 kVA laboratory prototype of a grid connected inverter has been built using a digital signal processor (DSP) TMS320F28335. Through comparative simulations and experimental results under grid disturbances such as harmonic distortion and imbalance, the effectiveness of the proposed DOB based current control scheme is demonstrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.609-612
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• 2008

The solid immersion lens (SIL) based near-field recording (NFR) system is considered as one of the high density optical data storage system. For the NFR servo system, tracking servo control is a difficult technology to maintain extremely small gap between SIL and media within one twentieth. This is because the track pitch is decreased for increasing the recording density. In this paper, we propose disturbance observer (DOB) and internal model principle (IMP) for disturbance rejection due to eccentricity of disk. The performance of tracking controller using DOB is increased by about 85%, 94%, 97% using Q filters that have bandwidths of 50Hz, 125Hz, 250Hz, respectively. Moreover, IMP based controller is effectively reduced the residual error.

• 제어로봇시스템학회:학술대회논문집
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• 1990.10b
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• pp.852-857
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• 1990

The purpose of this paper is to design a robust controller for a class of time-varying systems with bounded disturbance described by the differential equation. The robust desiging method proposed in this paper, called "incentive design method" is different from developed designing methods in the past, and has following properties. The robust control law designed by this method can guarantee a certain value of the cost functional no matter how the disturbance vary within the given bounds. Here, the certain value of the cost functional may not be a saddle-point value, but is the value selected by a system designer. Therefore, the bounded disturbance has at least no bad effect on the value of the cost functional during finite interval of time. The method is based on the theory of incentive differential games. In addition, the form of control law is constructed by the system designer ahead of time. A numerical illustrative example is given in this paper. It is shown from this derivation and this numerical example that the approach developed in this paper is effective and feasible for some practical control problem.l problem.

• Proceedings of the KSR Conference
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• 2006.11a
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• pp.189-197
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.5
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• pp.352-360
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• 2010

This paper proposes a precise position control of an automatic door using a disturbance observer. Although the conventional PID controller is usually used for an automatic door system, the demand of the robust controller considering the parameter deviations and disturbances is increasing due to the various size and weight of a door. The linear model for an automatic door system is presented. Based on this model, the LQR controller using a state feedback controller and an observer are suggested. A disturbance observer to compensate the undesirable factors is also proposed. Simulation and Experimental results are presented to illustrate the feasibility of the proposed control strategy.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1071-1072
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.81-89
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• 1997

In order to achieve the zero voltage regulation of the output voltage, the function control law will be used. In the previous function control law, only the proportional controller is used and the stability of the closed loop system was not analyzed. In this paper, for the realization of the control law, a new method to retrieve the low frequency component of the inductor voltage is proposed and analyzed. The large signal closed loop characteristics are alos analyzed to ensure the stable operation of the system disturbances. By using the function control law in the control system, the effect of the disturbance of the supply voltage is reduced in 93.3% for the direct dusty ration method. Also, in the effect of the disturbance of the load current, the output voltage has a logn recovery-time and is changed proportionally in the direct duty ratio method, but has stable in the function control law. Finally, the analysis shows that the disturbance of the output voltage being due to the supply voltage variation can be eliminated completely and the closed loop output voltage is insensitive to the disturbance of the load current. Therefore, it is proved that by using the function control law, the switching power supply with zero-voltage regulation output voltage can be realized.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.