$H_2$ Control for Head Positioning in Axial and Radial Dimensions for Self-Servo Track Writing

Du, Chunling; Xie, Lihua; Teoh, Jul Nee; Guo, Guoxiao

doi:10.1109/tcst.2007.903106

Cited by 16 publications

(12 citation statements)

References 7 publications

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“…The VCM actuator model involves two resonances at 4 and 8 kHz, and the controller is a proportional integral differential controller combined with notch filters. Assume that the disturbances and and noise in micrometers are generated by the models in [10] and scaled so that the track width is 0.23 m (track density 110 kTPI). RRO includes the first seven harmonics.…”

Section: Filtering Results and Impact On Servo Performancementioning

confidence: 99%

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Smoothing Position Error Signal Corrupted by Impulsive Disturbances

Gao

et al. 2009

IEEE Trans. Magn.

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This paper proposes a filtering method to smooth the position error signal (PES) contaminated by impulsive disturbances in hard disk drives. The impulsive disturbances, observed as sudden changes in PES, may be distributed separately or consecutively. A nonlinear switched filtering method is developed to remove the impulsive disturbances before the position error signal is fed into the servo controller. It turns out that the proposed filtering algorithm is able to effectively remove impulsive disturbances in the corrupted PES with no impact on the stability and the servo performance of the original servo loop.

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Section: Filtering Results and Impact On Servo Performancementioning

confidence: 99%

“…6, where . Suppose that the state-space representation of the open loop is given by (10) Let us have…”

Section: Impulsive Disturbance Filteringmentioning

confidence: 99%

Smoothing Position Error Signal Corrupted by Impulsive Disturbances

Gao

et al. 2009

IEEE Trans. Magn.

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“…Typically these servo sectors occupy about 10% of the total disk area. These patterns are written onto the disk on special machines (servo writers) before the disks are mounted onto the spindle of the disk drive, or they are written by the disk drive itself during the burn-in and test process [75]. This latter process is called "self-servo write," and can take many hours to format hundreds of thousands of data tracks.…”

Section: A Operation and Mechanical Specificationsmentioning

confidence: 99%

Control Methods in Data-Storage Systems

Cherubini

Chung

Messner

et al. 2012

IEEE Trans. Contr. Syst. Technol.

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Abstract-The recording performance of data-storage devices, in which write/read elements move relative to a storage medium to reliably store and retrieve information, depends on the capability of servo mechanisms to provide the necessary positioning accuracy. The desired characteristics of servo mechanisms for datastorage systems include robustness against variations of environmental parameters, high resolution, accuracy, stability, and fast response. This paper presents a comprehensive overview of advanced servo-control methods for data storage. The applications are to well-established recording technologies, including magnetic tape and magnetic disk systems as well as CD/DVD/Blue-Ray optical data-storage systems. Moreover, newer holographic and nearfield optical systems and the emerging probe-storage technology are also addressed. Emphasis is given to the potential exhibited by the technologies considered for achieving ultra-high storage capacity, as required by the exploding demand in data-storage capacity for archival systems and massive multimedia data storage.Index Terms-Control systems, hard-disk drive, holographic data storage, optical-disk drive, scanning-probe data storage, servomechanism, tape drive.

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“…However, all of the control techniques presented in [17][18][19] were formulated to satisfy sufficient rather than a sufficient and necessary conditions in order to convert the resulting optimization problems into semi-definite programs (SDP), involving linear matrix inequality (LMI) constraints by imposing some key matrices be block diagonal. Interested readers are referred to [17][18][19] for further details of this design technique. Moreover, because of the 2-D nature of the problem formulation, the controllers that are synthesized using this technique have a somewhat complicated structure, and are difficult to implement in actual applications.…”

Section: B Control Design Of Concentric Sstw Servo Systemsmentioning

confidence: 99%

Control design of concentric self-servo track writing systems for hard disk drives

Nie

Horowitz

2010

Proceedings of the 2010 American Control Conference

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Modern hard disk drives (HDDs) generate the head position error signal (PES) by reading special magnetic patterns called servo patterns, which are written in designated areas on the disk surface known as servo sectors, and measure the position of the head relative to the center of the data track. Servo sectors are typically created during the HDD manufacturing process and are not subsequently overwritten or erased. The process of writing servo sector patterns is known as servo track writing (STW). The accuracy and precision of the servo track writing process plays a crucial role in dictating the ultimate track density and areal storage density of the HDD. There are several mechanisms for performing servo track writing. Conventional servo track writing processes use additional sensing and positioning equipment external to the HDD. In contrast, self-servo track writing processes only use the HDD's reading and writing heads and servo system; thus avoiding many of the manufacturing cost increases and productivity losses associated with conventional servo track writing. This paper presents two novel controller synthesis methodologies for performing concentric self-servo track using a feedforward control structure. In the first methodology, it is assumed that a conventional track-following causal feedback compensator has been designed. A non-causal feedforward compensator, which utilizes the stored error signal that was created while writing the previous track, is subsequently designed using standard H ∞ control synthesis techniques, in order to achieve good disturbance attenuation while preventing the propagation of tracking errors from previous tracks. In the second methodology, both the track-following feedback compensator and the feedforward compensator are simultaneously designed via a mixed H 2 /H ∞ control scheme, which involves the solution of a set of linear matrix inequalities. Simulation results confirm that the two proposed control synthesis methodologies prevent error propagation from the previously written tracks and significantly improve self-servo track writing performance.

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$H_2$ Control for Head Positioning in Axial and Radial Dimensions for Self-Servo Track Writing

Cited by 16 publications

References 7 publications

Smoothing Position Error Signal Corrupted by Impulsive Disturbances

Smoothing Position Error Signal Corrupted by Impulsive Disturbances

Control Methods in Data-Storage Systems

Control design of concentric self-servo track writing systems for hard disk drives

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