• 정보저장시스템학회논문집
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• 제7권2호
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• pp.47-52
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• 2011

This paper presents a method to improve vibration characteristics of servo track write (STW) fixture. STW fixtures supported by flexible mounts are subject to various vibration sources. Using Finite element analysis (FEA) vibration modes of the fixture are identified. The FEA results suggest certain vibration modes be reduced through design change of flexible mounts to improve vibration responses of the fixture. Based on layered flexible mounts theory a parametric study on shear and bending stiffness is performed to obtain a suitable flexible mount design leading to increased resistance to rocking motion. Experiments confirm improvement of vibration characteristics and drive performance through new mounts design.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.694-699
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• 2002

As the demand for slim laptops requires ion'-height optical disc drives, vibration problems of optical disc drives are of great concern. Additionally, with the decrease of a track width and a depth of focus in high density drives, studies on vibration resonance between mechanical parts become more important. From the vibration point of view, the performance of optical disc drives is closely related with the relative displacement between a disc and an objective lens which is controlled by servo mechanism. In other words, to read and write data properly, the relative displacement between an optical disc and an objective lens should be within a certain limit. The relative displacement is dependent on not only an anti-vibration mechanism design but also servo control capability. Good servo controls can make compensation for poor mechanisms, and vice versa. In a usual development process, robustness of the anti-vibration mechanism is always verified with the servo control of an objective lens. Engineers partially modify servo gain margin in case of a data reading error. This modification cannot correct the data reading error occasionally and the mechanism should be redesigned more robustly. Therefore it is necessary to verify a mechanism with respect to the possible servo gain plot. In this study we propose the experimental verification method far anti-vibration mechanism with respect to the existing servo gain plot. This method verifies axial vibration characteristics of optical disc drives on the basis of transmissibility. Using this method, we verified our mechanism and modified the mechanism for better anti-vibration characteristics.

• 한국소음진동공학회논문집
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• 제12권11호
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• pp.833-839
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• 2002

As the demand for slim laptops requires low-height optical disc drives, vibration problems of optical disc drives are of great concern. Additionally, with the decrease of a track width and a depth of focus in high density drives, studies on vibration resonance between mechanical parts become more important. From the vibration point of view, the performance of optical disc drives is closely related with the relative displacement between a disc and an objective lens which is controlled by servo mechanism. In other words, to read and write data properly, the relative displacement between an optical disc and an objective lens should be within a certain limit. The relative displacement is dependent on not only an anti-vibration mechanism design but also servo control capability. Good servo controls can make compensation for poor mechanisms, and vice versa. In a usual development process, robustness of the anti-vibration mechanism is always verified with the servo control of an objective lens. Engineers partially modify servo gain margin in case of a data reading error. This modification cannot correct the data reading error occasionally and the mechanism should be redesigned more robustly. Therefore it is necessary to verify a mechanism with respect to the possible servo gain plot. In this study we propose the experimental verification method for anti-vibration mechanism with respect to the existing servo gain plot. Thismethod verifies axial vibration characteristics of optical disc drives on the basis of transmissibility. Using this method, we verified our mechanism and modified the mechanism for better anti-vibration characteristics.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.316-320
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• 2003

This paper introduces an autonomous underwater vehicle (AUV) model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the AUV docking test.

• 정보저장시스템학회논문집
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• 제1권1호
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• pp.99-107
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• 2005

According to recent trend, hard disk drive(HDD) has been smaller and less weight. Therefore, it needs new method of writing position information. In this thesis, a new controller that is suitable for SSW is proposed. The controller accepted SSW technology that is used to write position information in current HDD industry. The important condition to perform SSW is to reach constant velocity decided from the head velocity profile as fast as possible. The constant velocity decides the positional accuracy of spiral pattern and setup time decides the capacity of HDD. The head velocity profile as a reference signal must be designed not to cause resonance mode. The proposed controller was designed with consideration of these 3 elements, and it properly works for SSW. The velocity profile designed with SMART control not only minimizes the jerk, but also does not cause the resonance mode of a plant. After designing a conventional PID controller, it compared with electrical spring technique and ZPET technique.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1871-1874
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• 2005

The direct write FIB technology has several advantages over contemporary micro-machining technology, including better feature resolution with low lateral scattering and capability of maskless fabrication. Therefore, the application of FIB technology in micro fabrication has become increasingly popular. In recent model of FIB, however the feeding system has been a very coarse resolution of about a few ${\mu}m$. Our research is the development of nano stage of 200mm strokes and 10nm resolutions. Also, this stage should be effectively operating in ultra high vacuum of about $1x10^{-7}$ torr. This paper presents the discussion and results of CAE of the 2 axes stages. we have estimated the stable static and dynamic characteristics for dual servo system. Therefore the 2 axes stages developed and future work are introduced at the end of the paper.

• 한국소음진동공학회논문집
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• 제19권6호
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• pp.614-619
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• 2009

The STW(servo track writing) system which is the process of writing servo signals on disks before assembling in drives uses the spindle motor-chuck mechanism to realize low cost because the spindle motor-chuck mechanism has merit which can simultaneously write multi-disk by piling up disks in hub. Therefore, when the spindle motor-chuck mechanism of horizontal type operates in high rotation speed it is necessary to reduce the effect of RRO(repeatable run-out) and NRRO(non-repeatable run-out) to achieve the high precision accuracy of nano-meter level during the STW process. In this paper, we analyzed that the slip in assembly surfaces can be caused by the mechanical tolerance and clamping force in hub-chuck mechanism and can affect NRRO performance. We designed springs for centering and clamping considering centrifugal force by the rotation speed and assembly condition. The experimental result showed NRRO performance improves about 30 % than case of weak clamping force. The result shows that the optimal design of the spindle motor-chuck mechanism can effectively reduce the effect of NRRO and RRO in STW process.

• 한국산학기술학회논문지
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• 제22권2호
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• pp.781-788
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• 2021

본 논문은 K56 탄약운반장갑차의 주제어기와 서보제어기간의 통신에서 발생하는 통신오류를 개선하기 위한 설계에 관한 연구이다. K56 탄약운반장갑차는 K-55A1 자주포의 탄약 보급 및 적재를 자동화하여 운용을 보조하기 위한 장비이다. 탄약운반차의 캔통신보드는 주제어기의 내부에 탑재되어 서보제어기와의 통신을 위해 장착되는 핵심적인 기능품이다. 기존의 캔통신보드에서 정의되지 않은 오류가 간헐적으로 발생하는 문제점이 확인되었으며, 이로 인하여 탄적재 과정 중 탄약보급시스템 운용 중단 현상이 발생한 바가 있다. 본 논문은 발생된 문제를 해결하기 위하여 주제어기, 서보제어기간의 통신신호의 분석 및 기능시험을 통하여 고장 원인을 식별하였다. 또한 Read/Write 알고리즘 개선을 통한 재설계를 수행하여 오류 발생 현상을 해소하였다. 마지막으로, 제안된 원인 분석 및 설계의 유효성을 캔통신보드 단품 시험을 통하여 입증하였다. 이 연구가 캔통신보드의 신뢰성 향상을 통한 방위력 증진과 더불어, DPRAM을 이용하는 전자장치 전반의 신뢰성 향상에도 참고자료가 될 것으로 기대한다.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2003년도 춘계학술대회 논문집
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• pp.89-93
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• 2003

The Korea Research Institute of Ships and Ocean Engineering (KRISO), the ocean engineering branch of KORDI, has designed and manufactured a model of an autonomous underwater vehicle (AUV) to test underwater docking. This paper introduces the AUV model, ASUM, equipped with a visual servo control system to dock into an underwater station with a camera and motion sensors. To make a visual servoing AUV, this paper implemented the visual servo control system designed with an augmented state equation, which was composed of the optical flow model of a camera and the equation of the AUV's motion. The system design and the hardware configuration of ASUM are presented in this paper. A small long baseline acoustic positioning system was developed to monitor and record the AUV's position for the experiment in the Ocean Engineering Basin of KRISO, KORDI. ASUM recognizes the target position by processing the captured image for the lights, which are installed around the end of the cone-type entrance of the duct. Unfortunately, experiments are not yet conducted when we write this article. The authors will present the results for the docking test of the AUV in near future.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제11권1호
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• pp.65-70
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• 2011

The increased disk rotational velocity to improve the data transfer rate has raised up many serious problems in its servo control system which should control the position and velocity of a spot relative to a rotating disk. This paper proposes gain-scheduling-based track-seek control for single stage actuator of hard disk drives. Gain scheduling is a technique that can extend the validity of the linearization approach to a range of operating points and one of the most popular approaches to nonlinear control design. The proposed method schedules controller gains to improve the transient response and minimize overshoot during the functions of the read/write head positioning servomechanism for the seek control. The validity of the proposed method is demonstrated through stability analysis and simulation results.