• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.75-78
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• 2004

In an optical disk drive, a feeding system which is used to move the optical pick-up system to the target position and the proper control scheme of it are important in random access performance. Since the effect of control is directly affected by the modeling precision of the real system, the precise modeling to the real system should be acquired. Although a simple linear order modeling to the feeding system of an optical disk drive is useful in understanding of the overall dynamic characteristics, the dynamic characteristics which are belongs to the nonlinear area cannot be predicted correctly. Furthermore, the feeding system of an optical disk drive has many nonlinear characteristics such as a nonlinear friction and backlash. For this reason, the understanding of the nonlinear properties in the feeding system is very important. In this paper, the nonlinear items of the feeding system, friction and backlash, are introduced and the effect of it are investigated. Finally, the mathematical model considering the nonlinear properties is compared to the real system, and some comments of it are given.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.160.2-160.2
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• 2005

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.131-138
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• 1996

This paper suggests a servo control algorithm to reduce the repeatable tracking error which is not explicitly taken into account in the design of a conventional PID controller of a computer hard disk drive. The robust stability of the repetitive control system with multiplicative modelling error is analyzed, and the controller was implemented using a fixed point DSP(Digital Signal Processor). Experimental results show that the repetitive errors are suppressed effectively by the proposed controller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.227-232
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• 1998

This work focuses on the analysis of dynamic characteristics of an optical disk drive, Dynamic performance of the drive plays an important role in the design of a mechanism where the quality of servo mainly affected by the quality of controlling focus error and tracking error, A finite element model of the optical disk drive is presented to demonstrate its dynamic behaviors. Experimental results for the drive are presented and compared to predictions from the finite element model for verification. Using the finite element model, dynamic responses are predicted under internal and external excitations. Some design parameters of the vibration isolators are presented, satisfying the requirements of DVD drive system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.829-832
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• 2002

With the increase of storage density, high rotational speed and high access technologies in optical disk drive, mechanical issues, mainly noise and vibration, become critical. Up to now the researches of rubber mount for anti-vibration focused on how to calculate the static and the dynamic stiffness of rubber mount and leaved out of consideration of the dimensional tolerance of rubber mount for anti-vibration. This paper presents the effects of dimensional tolerance of rubber mount for anti-vibration on the dynamic characteristics of optical disk drive by finite element analysis and dynamic test. The relation between dimensional tolerance and dynamic characteristics of optical disk drive is observed and discussed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.1
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• pp.60-67
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• 2000

An improved disturbance rejection control scheme is presented for minimizing the position error due to the repeatable runout disturbances in high density disk drive systems The proposed control algorithm is capable of attenuating repeatable disturbances which is one of the major detractors to hard disk drive quality and performance. This is achieved by a sys-tematic combination of an optimal feedback component and a feedforward preview component. The feedback component is designed where the emphasis is placed on robustness. The feedforward component is on the basis of a preview control comprised of a measured disturbance signals which leads to better disturbance rejection capabilites. The designed con-troller is applied as a plug-in module to a high density hard disk drive with a pre-existing conventional servo controller. Simulations have been carried out to demonstrate the effectiveness of this control scheme in the reduction of the periodic disturbances.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.580-584
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• 1997

As the optical disk drive is getting applied to wider ranges, higher density of media and higher velocity of spindle motor are demanded and therefore its design criterion is becoming more strict. Especially, the vibration problem is one of the most important factors to be considered for reliable performance. In this study, the possibility of the application of the vibration absorber using rubber mount was investigated by 3 dimensional modeling and analysis by Recurdyn program. The model chosen was a vibration absorber using rubber mount installed on the sled base of the optical disk drive.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.127-133
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• 2002

After the vibration source is searched in optical disk drive as an information storage device broadly used the influence of it against FES(Focusing Error Signal) which is a kind of positioning error of pick up from the circuit is carefully examined. For that Purpose, partial coherence function method is applied on a simple multi-degree of freedom model made for the theoretical verification and it is practically introduced in optical disk drive for analyzing the effect of vibration source. Finally, partial coherence output spectrum is attentively observed in order to know which vibration source is a great influence on FES.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.755-761
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• 2003

Recently, the development of mobile devices demands information storage systems to use micro drive devices and cheap media. These should have several characteristics, for example, the subminiature of size, the robustness of shock, the minimum of cost and power consumption, and the removability of multiple applications. A conventional optical disk drive is more suitable for these specifications than the others. The optical storage system of the new generation to use a blue laser and a high numerical aperture (NA) is the perfect candidate for micro optical disk drives. In this paper, the micro actuator that can be applied to a micro optical disk drive is designed by response surface methodology to use a structural analysis and an electro-magnetic analysis. Based on above results, the coarse actuator and fine actuator are designed and improved from the point of view of the size and the power. Consequently, the designs of a micro actuator are proposed through these courses.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.54 no.6
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• pp.383-389
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• 2005

This paper proposes a pattern classification algorithm for the defect distribution of Hard Disk Drive (HDD). In the HDD production, the defect pattern of defective HDD set is important information to diagnosis of defective HDD set. In this paper, 5 characteristics are determined for the classification to six standard defect pattern classes. A fuzzy inference system is proposed, the inputs of which are 5 characteristic values and the outputs are the possibilities that the input pattern is classified to standard patterns. Therefore, classification result is the pattern with maximum possibility. The proposed algorithm is implemented with the PC system for defective HDD sets and shows its effectiveness.