• Journal of Institute of Control, Robotics and Systems
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• v.9 no.4
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• pp.284-295
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• 2003

The servo tracks of disk drives are constructed at the time of manufacture with the equipment of servo track writer. Because of the imperfection of servo track writer, disk vibrations and head fluctuations during servo track writing process, the constructed servo tracks might deviate from perfect circles and take eccentric shapes. The servo track writing error should be corrected because it might cause interference with adjacent tracks and irrecoverable operation error of disk drives. The servo track writing error is repeated every disk rotation and so is periodic time function. In this paper, we propose a new correction algorithm of servo track writing error based on iterative teaming approach. Our correction algorithm can learn iteratively the servo track writing error as accurately as is desired. Furthermore, our algorithm is robust to system model errors, is computationally simple, and has fast convergence rate. In order to demonstrate the generality and practical use of our work, we present the convergence analysis of our correction algorithm and some simulation results.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.11 no.1
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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.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.287-294
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• 2004

Dynamic Load/unload (L/UL) mechanism is an alternative to the contact start stop (CSS) technology which eliminates striction and wear failure modes associated with CSS. Inertia latch mechanism becomes important for mobile disk drives because of non operating shock performance. Various types of latch designs have been introduced in hard disk drives to limit a rotary actuator from sudden uncontrolled motion. In this paper, a single spring inertia latch is introduced for a small form optical disk drive, which uses a rotary actuator for moving an optical pick-up. A new small inertia latch with sin91e spring is designed to ensure both feasible and small size. The shock performance of the new inertia latch is experimentally verified.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.183-188
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• 2004

Nowadays optical disc drives have become necessary. As the equipment is popular to use, competition of price and rotating rate have been harder and harder. Shock response analysis for the optical disk drives is rarely studied. In this paper the optical disk drive has 5-DOF system and each motion is presented by using Lagrange Equation. As the motion of the Pick up lens is important to read and write data, it needs to consider the pickup and disk. The lumped parameter model is compared with finite element model in order to make sure of the result. Results of the shock response analysis from various shock inputs are gotten.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.222-225
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• 2001

Optical disk drives read information by replacing a laser beam on the disk track. As information has become larger, the more accurate position control of a laser beam is necessary. In this paper, we report the analysis and fabrication of the micro mirror for optical disk drivers. The mirror was fabricated by using MEMS technology and it's characteristics investigated. Also, electrode structure for reducing squeeze effect was discussed.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.958-961
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• 2002

The optical disk drive is a basic option on the PC now. So the lower price and higher read/write speed goods are now on market. These trends make many difficulties to produce more reliable drives, comparing when they are treated as high price stuff. In mechanical terms, the lower price and higher read/write speed drive make higher vibration and noise, lower stiffness, even severe fracture of cheap and low quality disk, problems. Due to the internal crash of P/U inside of the drive, the failure of drives, inferior drives, increase more and more by the careless transportation and the originated low stiffness parts. This report is the introduction of the FE simple model to decrease the internal P/U crash problems, and the results.

• Proceedings of the Korean Magnestics Society Conference
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• 1994.03a
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• pp.12-13
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• 1994

Magnetic recording is still considered to be a.leader in storage industries in general. The rigid disk drive, in particular, has an advantage over tape, optical, magneto-optical, or flash memories, because of high areal density and fast access time with reasonably low cost per Mbyte. However, to be competitive in the market and to keep an edge over other storage devices, head and media in rigid disk drives require better performance per cost and more aggressive improvement in areal density, as shown in Fig. 1, than before. In this review paper, the future trend in head/media technologies of the rigid disk drive has been reviewed. Thin film media and thin film inductive/MR heads will be mainly discussed, since they are expected to be dominant in the future high-end drives over other technologies, such as particulate media or MIG heads.(omitted)mitted)

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.2
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• pp.104-112
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• 2002

Controllers for acoustic noise reduction in disk drives have been developed but they have slower seek time performance than time-optimal controllers. We propose a new seek servo controller that has acoustic noise reduction benefit and faster seek time performance than conventional controllers. The proposed controller is designed to make sure that head is moved with maximized acceleration and deceleration under the voltage limitation imposed on head-positioning motor and so it provides faster seek time than conventional controllers designed by considering the current limitation. The experimental results using a commercially available disk drive confirm that the use of the proposed controller results in foster seek time than conventional controllers for acoustic noise reduction.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.492-498
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• 2000

As the disk rotation speed increases in information storage devices, aerodynamically excited disk vibration is induced by airflow around the disk. This paper investigates theoretical and experimental studies on the disk flutter instability in CD-ROM drives. The effect of airflow on the disk vibration is modeled as the distributed damping and lift forces. By analyzing the eigenvalue problem of the aero-elastic coupling model, we introduces a novel technique to predict the flutter speed by comparing experimental natural frequencies with analytical ones of a disk rotating in vacuum. The new method predicts that the vibration mode with two nodal diameters in a CD disk experiences the first flutter instability at 12,000 rpm.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.7
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• pp.539-546
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• 2002

This paper presents a new direct seek control scheme that provides fast data access capability and robust performance for high-speed rotational optical disk drives (ODD). When a disk is rotating at a high speed to obtain fast data transfer in ODD, the magnitude and frequency of velocity disturbance caused by eccentric rotation of the disk increase in proportion to the rotational speed of the disk. Such disturbances make it almost impossible for the conventional seek control scheme to achieve stable and satisfactory seek performance. We analyze the problems that may arise when the conventional seek control scheme is applied to the high-speed rotational ODD and propose a new direct seek control scheme that will solve such problems. In the proposed scheme, a seek control system is designed such that its performance is guaranteed for a set of plants with parameter perturbations. The performance of the proposed seek control scheme is shown by experiments using a high-speed rotational ODD.