• Proceedings of the KSME Conference
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• 2000.04a
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• pp.475-480
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• 2000

A new positioning mechanism with Parallel type actuator using piezoelectric material and with dual type actuators using voice coil motor (VCM) and piezoactuator is proposed for optical disk drive or near-field recording type drive, and high speed position and vibration control are investigated. Parallel type bimorph piezoactuator is used as a fine motion actuator with self-sensing technique, which allows a piezoelectric material to concurrently sense and actuate in a closed loop frame work, and positive position feedback control algorithm is adopted to further control residual vibration. For positioning control of VCM, PID control algorithm is adopted.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.775-779
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• 2003

Recently, a new type actuator using multi-pole magnet has been developed for high-density and high-speed disk drive, which can be achieved higher sensitivity than a conventional actuator for applying one-pole magnet. However, it is very difficult for the actuator of multi-pole magnet to meet simultaneously the optimal design condition for reducing rolling mode effect and improving driving sensitivity because the force center is different from the mass center In this paper, First We propose the new shape coil for tracking which can reverse moment additionally in tracking motion, Next we achieve the optimal design to reduce phase disturbance and peak gain at the rolling mode frequency. Finally, the validity of the proposed methods is proved from experimental results.

• Transactions of the Society of Information Storage Systems
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• v.7 no.1
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• pp.13-18
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• 2011

As a standard of optical disk drive (ODD) was determined to Blu-ray diks (BD), researches for securing slim drive thickness, high data transfer rate and high capacity have been progressed. The actuator for applying BD is also required to have high performances, such as compatibility, slim thickness and 3-axis motion. In this paper, an asymmetric dual lens actuator is proposed to satisfy abovementioned performances. To design the actuator in a limited space, stress analysis and design of experiment (DOE) are performed to reduce weight of moving part and increase driving force and flexible mode frequency. Consequently, the final model, which is satisfied with specifications, is secured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.65-69
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• 2004

The small form factor optical data storage devices are developing rapidly nowadays. Since it is designed for portable and compatibility with flash memory, its components such as disk, head, focusing actuator, and spindle motor should be assembled within 5 m thickness. The thickness of focusing actuator is within 2 mm and the total working range is $+/-100{\mu}m$, with the resolution of less than $1{\mu}m$. Since the thickness is limited tightly, it is hard to place the yoke that closes the magnetic circuit and hard to make strong flux density without yoke. Therefore, Halbach array is adopted to increase the magnetic flux of one side without yoke. The proposed Halbach array type focusing actuator has the advantage of thin actuation structure with sacrificing less flux density than conventional magnetic array. The optical head unit is moved on the swing arm type tracking actuator. Focusing coil is attached to swing arm, and Halbach magnet array is positioned at the bottom of deck along the tracking line, and focusing actuator exerts force by the Fleming's left hand rule. The working range and resolution of focusing actuator are analyzed with FEM and experiment.

• Journal of Institute of Convergence Technology
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• v.1 no.2
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• pp.6-15
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• 2011

This paper reports the design and fabrication of a micro-electro-mechanical-system(MEMS)-based electrostatic angular microactuator for a dual-stage servo. The proposed actuator employs a novel electrode pattern named "skewed electrode array(SEA)" scheme. It is shown that SEA has better linearity than a parallel plate type actuator and stronger force than a comb-drive based actuator. The moving and the fixed electrodes are arranged to make the driving force perpendicular to the rotating moment of arm. By changing the electrode overlap length, the magnitude of electrostatic force and stable displacement will be changed. In order to optimize the design, an electrostatic FE analysis was carried out and an empirical force model was established for SEA. A new assembly method which will allow the active electrodes to be located beneath the slider was developed. The active electrodes are connected by inner and outer rings lifted on the base substrate, and the inner and outer rings are connected to platform on which the slider locates. Electrostatic force between active electrodes and platform can be used for exiting out of plane modes, so this provides the possibility of the flying height control. A microactuator that can position the pico-slider over ${\pm}0.5{\mu}m$ using under 20 volts for a 2 kHz fine-tracking servo was designed and fabricated using SoG process.

• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.243-250
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• 2007

This paper presents a systematic method of estimating a velocity disturbance occurring in the fine seek control system of an optical disk drive. A fine seek loop gain adjustment algorithm is introduced to accurately estimate the velocity disturbance in spite of the uncertainties of the fine actuator. The velocity disturbance can be estimated from a measurable velocity, a fine seek controller output, and a compensated fine actuator model. A robust fine seek controller can be designed by considering a minimum fine seek open-loop gain, calculated by the estimated velocity disturbance. The proposed controller design method is applied to the fine seek control system of a DVD rewritable drive and is evaluated through the experimental results.

• Proceedings of the KIEE Conference
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• 2004.05a
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• pp.26-28
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• 2004

The sliding mode control law provides a robust solution for general control problems. Most real systems which use a portable hard disk drive have to overcome disturbances and model uncertainties for proper operation. The chattering effect caused from unexpected oscillation can make the system be unstable. Therefore, we propose a robust control algorithm for the nonlinear second order systems with model uncertainties and disturbances. The proposed algorithm is designed following a sliding mode and observer based control. Thus the proposed algorithm has more expanded bounded region of control. Simulation results show the robustness of the proposed controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.742-747
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• 2000

The optical storage device has recently experienced significant improvements, especially for the aspects of high capacity and fast transfer rate. However, it is the fact that the optical storage device has the lower access time for the randomly scattered data compared to the hard disk drives. It is, therefore, necessary to develop a new type of optical storage system. In this study, we investigate the air bearing characteristics for the optical disk drives which have the swing arm actuator similarly to the hard disk drives. Considering the requirements of the optical disk drives, we parametrize the shape of the air bearing surface and investigate its sensitivity to the flying characteristics for further optimized design outputs.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.178.1-178.1
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• 2007

• Journal of Mechanical Science and Technology
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• v.17 no.5
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• pp.679-690
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• 2003

As the rate of increase in areal density of the HDD has accelerated, dynamic characteristics of the HDD actuator need to be improved with respect to the performance of the tracking servo and shock transmission. Therefore, it is important to analyze the vibration characteristic of the HDD actuator that consists of the VCM part, E-block and pivot bearing. In this paper, vibration modes of the HDD actuator are investigated the using finite element and experimental modal analyses methods. To develop a detailed finite element model, finite element models of each components of the actuator assembly are constructed and tuned to the results of the EMA. The VCM coil is modeled as an equivalent finite element model that has an orthotropic material property using auto-model updating program. Auto-model updating program with improved sensitivity based iterative method is applied to build a detailed finite element model using the result of the EMA. A detailed finite element model of the HDD actuator is then constructed and analyzed.