• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.2
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• pp.221-230
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• 1988

In the microcomputer-based velocity control for an electro-hydraulic servo system, the effects of control methods and control hardware on the performance of the system were investigated. Experiments were carried out with PID and deadbeat controllers using 8 or 16 bit microprocessor and 8 or 12 bit A/D and D/A converters. It is found that the transient response of the system is better with PID controller than with deadbeat controller. When the number of bits of the microprocessor and converters are small, it is also found that amplitude quantization due to limited word-length gives significant effects on transient responses of the system. Analytically predicted step responses are in good agreement with experimental ones.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.289-299
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• 2019

Attitude control modeling and simulation (M&S) can be extensively applied in overall development process, from simple algorithm design to on-board software verification. This paper introduces CMG-based attitude control M&S software, which consists of 6-DOF modeling (CMG and space environments modeling), and attitude control algorithm. The M&S software is divided into three modules, from an inner CMG motor control module to an outer earth observation mission module. While an application of this developed software is currently limited to the initial-phase attitude controller development, its application area can be extended to the later-phases by considering sophisticated model information in future.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.173-179
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• 2014

In this paper, a motor parameter identification system has been implemented to improve the performance of the position sensorless stroke controller for linear compressors. In order to control the cooling capability of a refrigerator or an air conditioner in which linear compressors are applied, the piston speed should be controlled. The piston speed control can be obtained by adjusting the frequency or the stroke of linear motors. The dynamic performance of linear compressors depends on how accurately the stroke or the piston amplitude is estimated. The merits and demerits of Constant method and PIM (Parameter Identification Method) concerning the needed memory space and the stroke error are discussed and verified via some experimental studies.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.1
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• pp.33-38
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• 2002

In this paper, a Two-Degree-of-Freedom-Controller(TDFC) for DC motors based on inverse dynamics and the fuzzy technique is presented. The proposed controller includes the inverse dynamic model of a DC motor system, a prefilter and a fuzzy compensator. The model of the system is characterized by a nonlinear equation with coulomb friction. The prefilter eliminates high frequency effects occurring when the inverse dynamic model is implemented. The fuzzy compensator is designed for tracking the change of the reference input and simultaneously regulating the error between the reference input and the system output which can be caused by disturbances. The optimal parameters of both the model and the compensator are identified by a real-coded genetic algorithm. An experimental work on a DC motor system is carried out to verify the performance of the proposed controller.

• Journal of Biosystems Engineering
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• v.25 no.5
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• pp.351-358
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• 2000

This study was conducted to develop a speed control system of a DC motor which drove a barley seeder mounted on a combine harvester. Barley seeder mounted on a combine has been known to reduce labor and cost of barley cultivation. However, development of the seeder has been unsuccessful because the combine, a dedicated rice and barley harvester has not enough space and proper power take-off for barley seeder. To develop a barley seeder, small powered motor speed controller was required. A proximity sensor for detecting working speed of the combine and a programmable one board microprocessor was used to develope a control system. Motor parameters and motor constant, relationship between seeding rate, motor speed, groove volumes of a tested roller, torque were measured. The proximity sensor sent a frequency signal to the microprocessor. In laboratory experiments, the excitation voltage of the motor was shown not to be proportional to the size of pulse width (duty ratio). A table transforming frequency signal, that represented for working speed to proper pulse width was developed from seeding rate experiments. However, seeding rate at low frequency signal was not proportional to the working speed. Seeding rate control proportional to the frequency signal was achieved by shifting of the frequency signal.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.8
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• pp.705-713
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• 2014

In this paper, we propose a novel velocity ripple controller using phase compensation feedforward control. Velocity ripples result in many kinds of performance degradations in manufacturing machines, especially such as ultra-precision roll lathes. The generation of velocity ripple in constant velocity control comes from various causes, such as electrical torque ripples, mechanical worn out, inconsistent mass center, etc. Conventional researches about ripple is mainly for reducing torque ripple in actuator level, which is only one of reasons for velocity ripples, so in this study, we focus on eliminating velocity ripples in upper level controller using phase compensation feedforward controller. The proposed algorithm is composed of several modules, such as ripple extractor, phase adjuster and phase follower etc. The suggested algorithm can be easily extended, and it shows a superior performance in the experiments of ultra-precision roll lathes.

• Journal of Aerospace System Engineering
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• v.12 no.1
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• pp.17-26
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• 2018

The interaction model between variable-speed control moment gyros and a satellite has been studied based on the multi-body dynamics. Using the interaction model, we could obtain data for the design of VCMG motors and the strength design of structure. The interaction effects of flexible modules such as solar panels were included. Flexible modes are excited by the satellite's maneuver, and these modes cause perturbations in the satellite attitude. We developed a simulation program by Modelica and verified the proposed model.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2005.04a
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• pp.229-232
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• 2005

본 논문에서는 다수의 로봇이 협동 제어 및 분산 제어를 목적으로 고안된 DARS 로봇의 마이크로 컨트롤러가 적은 메모리를 내장하여 영상 처리와 같은 많은 데이터를 처리하는 부분에서는 여러 제약이 생기는 문제점을 해결하기 위하여 DARS 로봇의 영상 처리 및 전송에 있어 데이터의 전송량을 줄이는 방법으로 영상 압축 방식을 사용하여 영상 압축 데이터의 전송을 구현하였다. 또한 DARS 로봇이 이동하면서 특정 미션의 수행이 가능하도록 배터리로 정전압을 공급하고, 물체를 감지하는데 있어 사각이 없이 $360^{\circ}$전 방향을 감지하도록 적외선 센서부를 설계하였다. DARS 로봇의 이동이 용이하도록 설계된 모터 구동부는 센서에 감지되는 물체의 거리에 따라 DARS 로봇이 속도를 정밀하게 가$\cdot$감속 제어를 하고, 마이컴 제어부는 카메라로부터 입력되 영상 신호를 압축 알고리즘을 이용하여 압축하고, 압축된 데이터를 컴퓨터로 전송한다. 컴퓨터에서는 입력된 영상을 Visual c++을 사용하여 화면 표시 및 DARS 로봇을 제어 할 수 있도록 구현하였다.

• 기계와재료
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• v.25 no.3
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• pp.6-15
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• 2013

유압프레스의 단점을 극복하기 위해서 서보모트를 장착하여 성형속도를 높인 서보 유압프레스를 개발하게 되었으며, 특히나 서보모터를 국내산으로 적용하여 듀얼형으로 유압시스템의 효율성을 높여 최종적으로 개발함으로써 서보 유압프레스를 완전 국산화하였다. 또한 하사점 위치 제어의 용이성을 확보하기 위해 프레스 램용 메인 실린더에 톱니나사부를 만들어 임의의 위치에 정지할 수 있는 정지정도 및 하사점 위치 제어정밀도를 향상시켰으며, 유량의 미세 제어를 통해 프레스 램의 동작성을 개선코자 하였다. 다이쿠션은 메인 실린더와의 연계 제어를 통해 제품의 손상 방지 및 제품 추출의 용이성을 확보하였으며, 소재의 종류나 제품의 형상 특성에 따라 프리모션 제어가 가능한 지식기반형 자율제어 시스템을 적용하였다. 듀얼 서보시스템과 유압펌프가 연계구동함에 따라 기존 유압프레스 보다 약 40%이상의 에너지절감을 달성할 수 있을 것으로 예측되며, 현재 에코머신 인증제도에 대한 논의가 활발한 시점에서 매우 적합하고 필요한 하이브리드형 서보 유압프레스의 국산화 개발 사례라고 하겠다.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2218-2220
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• 2003

현대 산업현장에서 80%이상 사용되는 PID(proportional integral derivative) 제어기는 제어성, 적응성, 제어이득 조정 등의 특정이 있어나 제어 대상에 대한 PID 제어 계수를 경험적 방법인 수동으로 동조해야하는 문제점이 있다. 이를 개선하기 위해 본 논문에서 PID제어기의 최적 자동동조를 위한 릴레이 동조 방법을 제안한다. 기존의 한계감도법과 과도응답 법으로 초기계수를 결정하는 방법보다 유연성과 적용성이 높고, 이를 마이크로프로세서(DSP : TMS-320C32)에 적용하여 소프트웨어적으로 릴레이의 기능이 이루어지도록 설계했다. 이는 Ziegler-Nichols 계수조정법이 갖는 적용대상의 제약성을 극복한 방법이며, 릴레이에 의해 출력을 강제 진동시키고 출력의 진폭과 주기를 이용하여 PID 계수를 조정하고, 또 상대안정성의 척도인 위상여유를 고려하므로 시스템의 상대안정성과 견실성을 향상시킬 수 있음을 확인하였다.