• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.370-372
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• 2004

This paper addresses the wavelet-based fuzzy PI/PD controller design using DNA coding method. A structure of fuzzy controller model is adopted as the wavelet transform of which the coefficients are identified. The proposed method overcomes some mathematical limits of conventional methods by using the fuzzy logic that is optimized by DNA coding method. The feasibility of the proposed fuzzy controller design scheme is verified by applying to the servo control of the optical disk drive.

• 정보저장시스템학회:학술대회논문집
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• 2005.10a
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• pp.2-3
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• 2005

Air gap control method using a conventional actuator for near field recording technology has been reported. To achieve good performance in the air gap servo and further experiments, the assembling between OL and SIL is the critical procedure. A lens set with NA 1.45 at 405 m has been assembled and tested by using a Twyman-Green interferometer. The tolerance of assembling is very tight and the designing and adjusting procedure must be carefully controlled.

• Current Optics and Photonics
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• v.5 no.3
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• pp.289-297
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• 2021

We describe a comb-mode resolving spectroscopic technique by direct time-domain phase correction of unstable interferograms obtained from loosely locked two femtosecond lasers. A low-cost continuous wave laser and conventional repetition rate stabilization method were exploited for locking carrier and envelope phase of interferograms, respectively. We intentionally set the servo control at low bandwidth, resulting in severe interferograms' fluctuation to demonstrate the capability of the proposed correction method. The envelope phase of each interferogram was estimated by a quadratic fit of carrier peaks to correct timing fluctuation of interferograms in the time domain. After envelope phase correction on individual interferograms, we successfully demonstrated 1 Hz linewidth of RF comb-mode over 200 GHz optical spectral-bandwidth with 10-times signal-to-noise ratio (SNR) enhancement compared to the spectrum without correction. Besides, the group delay difference between two femtosecond pulses is successfully estimated through a linear slope of phase information.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.1332-1335
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• 1996

It is very important to predict the future position for the heavy vehicle with evasive maneuvering. In this paper, we considered for the manual image tracking system. The vehicle images are received from gyro stabilized mirror system, pass through the optical lens, processed, and displayed on the TV monitor. The operator try to lay the reticle to the center of vehicle image. When the vehicle is moving, the mirror platform (actually the line of sight) should follow the vehicle and the angular rate information is picked up from the mirror stabilized system. This rate signal should be used to predict the future vehicle position. The problem is that the visual system of the human operator is in the closed loop system. The rate signals are disturbed by the operator. In addition, there are some non linearities concerned with the control handle bar and the servo control system. The proposed Kalman filter, combined with some modifications for operator disturbance rejection, improved the predication of the future vehicle position when compared with the conventional passive filter used.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.5
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• pp.432-438
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• 2005

In this paper, the high precision position control of AC Servo motor for semiconductor equipment is studied. The control system was implemented using TI DSP TMS320F2812 which has 150 MIPS speed for next generation motor control. The controlled 100W PMSM motor has 2,500 ppr optical incremental encoder. The control system has speed controller and current controller to control the motor position. The encoder pulses are divided into 4 times, which has 10,000 ppr and the motor system has the position accuracy of 1/10,000. If the resolution of the encoder is increased, the resolution of the position control will be increased.

• 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.1276-1286
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• 2005

In this paper, the dual stage interaction between the coarse actuator and the fine actuator of an optical disk drive is studied, and the new control method to enhance the track pull-in performance using fine actuator control is proposed. First, the dynamic analysis for the dual stage and the experiments to find the each actuator dynamics are performed. From the experiments, some physical parameters of the actuators were derived, then, some simulations are performed to find the interaction effect of the fine actuator during seek motion. Second, the center servo which suppresses the vibration of fine actuator during seek motion is designed and evaluated. And the fine actuator control to reduce the relative velocity between the target track and beam spot is proposed. From simulations, we show that fine actuator control which has same frequency and same phase of the disturbance is effective to reduce the relative velocity, and this result leads to track pull-in enhancement. Hence, the proposed control method is good approach to improve the track pull-in performance. Finally, the realization of the proposed method and some comments of it are briefly discussed.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.218-223
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• 2002

광 디스크 드라이브에서의 서보 제어시스템에는 광 픽업에서 발생된 레이저 빔을 디스크 기록면의 데이터 트랙에 정확히 위치시키기 위한 제어 계를 갖고 있다. 광 디스크의 고배속화에 따른 외란의 주파수 대역의 증가에 따라 더욱 더 높은 샘플링 주파수로 레이저 빔의 위치 제어를 필요로 하게 되고, 여러 가지 알고리즘의 증가로 인해 DSP의 연산 부담은 증가하게 된다. 본 논문에서는 서보 제어에 필요한 알고리즘의 최적화된 하드웨어/소프트웨어 시스템을 구현하고 이를 이용한 실험 결과를 제시한다.

• Proceedings of the KSRS Conference
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• 2004.10a
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• pp.448-451
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• 2004

MSC (Multi-Spectral Camera) system is an electro-optical camera system which is being developed to be installed on KOMPSAT-2 satellite. High resolution image data from MSC system will be transmitted to the ground-station through x-band antenna called APS (Antenna Pointing System). APS is a directional antenna which will point to the receiving antenna at ground station while the satellite is passing over it. The APS needs to be controlled accurately to provide the reliable communication with big RF link margin. The APS is controlled by ATS (Antenna Tracking Software) which is included in the MSC software. ATS uses the closed loop control algorithm which will use TPF (Tracking Parameter File) as an input for antenna position, and will use two resolve readings from APS as a feedback. ATS has been developed and verified using APS QM (Qualification Model) and all the control parameters for ATS have been tested and verified. Various kinds of maximum, nominal and realistic dynamics for the APS movement have been simulated and verified. In this paper, closed loop servo control algorithm and obtained APS position error from the verification test with APS QM will be presented in detail

• Journal of Welding and Joining
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• v.8 no.3
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• pp.60-69
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• 1990

Plasma arc cutting is a fusion cutting process in which a gas-constricted arc is employed to produce a high-temperature, high-velocity plasma jet on the workpiece. This process provides some advantages such as increased cutting velocity, excellent working accuracy and the ability to cut special materials (widely used stainless steels and Al-alloys, for example), when compared with iconventional oxyfuel gas cutting. From the view point of price and reliability of the power source, plasma arc cutting has also some distinct advantages over laser beam cutting. High-speed machines with NC or CNC systems are needed for the plasma arc or laser beam cutting process, while for oxyfuel gas cutting, low-speed machines with copying templates or optical-shape tracking sensors can be applied. The low price and high flexibility of the microprocessor arc contributing more and more the application of CNC system in the plasma arc cutting process, as in other manufacturing fields. From these points of view, a microprocessor-based plasma arc cutting system was developed by using a reference-pulse system, and its performance was tested. The interpolating routines were programmed in the assembly language for saving the memory volume and improving the compouting speed, which has an intimate relationship with the available cutting velocity.

• Journal of the Korea Society of Computer and Information
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• v.18 no.12
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• pp.55-64
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• 2013

In this paper, the HILS (Hardware In-the-Loop Simulation) system to analyze and to verify the performance of the targeting pod is addressed. The main functions of the targeting pod is acquiring and tracking targets to guide a LGB (Laser Guided Bomb) to the targets. For the analysis of targeting pod, the real time simulate images generation of IR and daylight cameras, sever control technology, and the analysis of laser transfer characteristics are necessary. For the real time image generation and the laser transfer characteristics analysis, off-the-shelf SDK(Software Development Kit) OKTAL-SE is used. For the servo controller, well-proven mechanism in the previous program is applied to increase servo control accuracy. To analyze the performance of a targeting pod in a realistic environment, 1553B, ARINK818 interface and etc. which are actually implemented in real combat aircrafts are applied in the system. By using the developed HILS system, the performance of currently operating targeting pods in real combat aircrafts can be analyzed and predicted. Additionally, the relationship between overall system performance and each module performance can be analyzed, the currently developed HILS system is expected to be a very useful tool to generate system development requirements of targeting pods and to reduce any possible future development risks.