• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.8 no.3
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• pp.88-95
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• 1994

A scheme of IESFVSC(Integral Error State Feedback Variable Structure Controller) is proposed for a DC servo position control system with the disturbances which do not satisfy the matching condition. The proposed control system is composed of servo compensator and state feedback VSC. The servo compensator enhances the robustness of the control system against various types of disturbance, and makes effective tracking possible without using error dynamics. The IESFVSC is applied to the practical design of a robust DC servo control system and the control performances are verified through theoretical analyses and simulations.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.395-403
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• 2006

This paper has proposed a new dead time compensation method for a voltage-fed PMW inverter. In the voltage-fed PMW inverter, a voltage distortion is generated by the dead time effect and the nonlinear characteristics of the switching devices. Especially, the distorted voltage causes 5th and 7th harmonics in the stationary phase currents, and 6th harmonic in the synchronous phase currents. As a result, the integrator output of the synchronous PI current regulator has the ripple corresponding to six times of the inverter output frequency. In this paper, the signal of the integrator output of the d-axis current regulator is used as the control signal for the dead time compensation. The experimental and simulation results are presented to verify the validity of the proposed method.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.3
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• pp.20-29
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• 2008

In this paper, we propose a do-interlacing algorithm using integral projection-based motion estimation considering Region Of Interest(ROI). The proposed motion estimation method finds the motion of the given ROI accurately with low computational cost. In order to incorporate the motion estimation in do-interlacing, an entire image is first segmented into multiple ROIs according to the temporally predicted block-wise motion types and spatial positions. Then, motion vectors of respective ROIs are obtained by the integral projection method. In this paper, totally five ROIs, one for the global motion and four for the local motions, are made, and therefore, five motion vectors are produced for each field. By using the estimated motion vectors, motion compensation is performed for increasing the vortical resolution of the converted frames. Finally, do-interlaced frames are obtained by effectively combining the results of motion compensation and stable intra-field do-interlacing according to the reliability of motion compensation. Experimental results show that the proposed algorithm provides better image quality than existing algorithms in both subjective and objective measures.

• Journal of Internet of Things and Convergence
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• v.10 no.2
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• pp.51-60
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• 2024

Aiming at the problem of low contrast and difficult to recognize video images in low-light environment, we propose an adaptive contrast compensation enhancement algorithm based on human visual perception. First of all, the video image characteristic factors in low-light environment are extracted: AL (average luminance), ABWF (average bandwidth factor), and the mathematical model of human visual CRC(contrast resolution compensation) is established according to the difference of the original image's grayscale/chromaticity level, and the proportion of the three primary colors of the true color is compensated by the integral, respectively. Then, when the degree of compensation is lower than the bright vision precisely distinguishable difference, the compensation threshold is set to linearly compensate the bright vision to the full bandwidth. Finally, the automatic optimization model of the compensation ratio coefficient is established by combining the subjective image quality evaluation and the image characteristic factor. The experimental test results show that the video image adaptive enhancement algorithm has good enhancement effect, good real-time performance, can effectively mine the dark vision information, and can be widely used in different scenes.

• Journal of the Institute of Convergence Signal Processing
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• v.8 no.3
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• pp.217-221
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• 2007

This paper deals with the robust nonlinear controller design using output feedback for a Chua circuit which is one of the well-known nonlinear models. First, an exosystem for reference signal tracking is defined, and error dynamic equations are derived from the differentiation of the output tracking error equation. The normal sliding surface is modified using the integral type servo compensator. The parameters in the equations of the modified sliding surface and servo compensator are determined by using the Hurwitz condition of stability. Especially the error signals can't be obtained directly from the output because all parameters are assumed unknown. So instead, a high gain observer is designed. From this estimated error signals, a stabilizing controller is designed. Simulation is done for demonstrating the effectiveness of the suggested algorithm.

• Journal of the Korean Institute of Telematics and Electronics
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• v.17 no.4
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• pp.45-52
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• 1980

In order to eliminate the phase errors caused by the finite GB product of operational amplifiers, novel integnator circuits are proposed. These circuits are characterized by their positive phase error angles and integrator selectivity. The positive sign of the Q and of the circuits compensates the negative selectivity and phase error angles, inherent in the integrated operational amplifiers. Miller inverting intergrator of a biquad circuit realized by Thomas is replaced by the proposed circuit and the band-pass frequency response of the modified biquad network is experimentally analyzed. A considerable improvement is recognized to such extent that the center frequency of the band-pass filter is allowed to be shifted up to 20KHz, which has been infeasible with conventional biquad networks.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.5
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• pp.859-866
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• 2022

Active disturbance rejection control is a method in which the disturbance is removed from the controller by estimating the state variable using the Luenberger observer. The Luenberger observer is estimated by defining a nonlinear term including disturbance with constant characteristics in a steady state as a state variable. It can be shown that the speed tracking performance is improved by compensating the estimated state variable to the PI controller and the IP controller. The disturbance removal performance of the tracking control can be confirmed by observing that the estimated state error is within 1.9 [%] in the case of load fluctuation and the steady-state state tracking error converges to zero.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.2
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• pp.139-148
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• 1997

본 논문에서는 비선형 마찰이 존재하는 조준경 안정화 시스템에 대해서 마찰력 보상과 성능개선을 위한 신경망제어기의 설계방법을 제시한다. 제안한 신경망제어기는 비례, 적분, 진상(PI/LEAD) 제어기와 신경회로망과의 병렬로 구성되며, 제어 목적은 비선형 마찰과 외란이 존재하여도 안정거울의 각속도 추적성능과 안정화 성능의 향상에 있다. 신경회로망의 입력으로 안정거울의 각속도 추적오차와 추적오차의 적분, 제어입력이 필터를 통과한 신호가 사용되며, 신경호로망은 간접학습구조에 의해 학습된다. 조준경 시스템의 비선형 마찰력인 쿨롱마찰력의 크기가 외부환경에 따라 변하는 경우와 시스템으로 외란이 인가되는 경우에 대하여도 제안한 병렬제어기는 기존의 PI/LEAD 제어기보다 추적과 안정화 성능면에서 우수함을 컴퓨터 모의 실험으로 확인한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.2
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• pp.125-130
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• 1998

This paper describes a novel flux calculator for the estimation of real rotor flux angle which is indispensable to the field oriented control of induction motors. A pure integrator is used to estimate the real rotor flux precisely from voltage and current information. The proposed flux calculator adopts the new drift compensation method to overcome the drift problem of pure integrator. The motor speed is calculated using estimated flux angle and estimated slip frequency. The performance of this approach is verified through the experiment. The experimental results shows stable operation of proposed system even below 1/100 of rated speed.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.509-513
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• 1999

본 논문은 유도전동기의 직접벡터제어 시스템에서 전동기가 기동 시 토크 충격없이 부드럽게 기동할 수 있는 기동기법을 제시한다. 직접 벡터제어에서 고정자 자속을 계산 시 사용되는 적분기 문제를 해결하기 위하여, 인버터주파수에 따라 시정수를 제어하는 프로그램어블 3-단계 저역필터를 적용한다. 이 3-단계 저역필터는 거의 완벽한 적분기능을 수행 할 수 있으나, 이 저역필터는 고정자 자속의 시간지연을 유발하므로 기동 시 전동기 토크의 충격을 발생된다는 문제점이 있다. 따라서, 기동시 고동자 자속의 시간지연을 보상하는 고장자 자속의 피이드포워드 기법을 제시하여, 전동기 기동 시 토크 충격을 방지한다. 시뮬레이션을 통하여, 이 기동기법의 타당성을 확인한다.