Distortion effects on servo position error transfer function

Ho, H.T.; Doan, T.

doi:10.1109/20.595916

Cited by 4 publications

(2 citation statements)

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“…As the track density of HDD can achieve 200 000 tracks per inch (TPI) and is increasing towards a target density of 10 Tb/in 2 , it is essential to improve the tracking performance of STW to support writing of qualified servo patterns at such a high track density. One of the major factors is the written-in repeatable runout (RRO), which has a direct effect on linear characteristics of the PES transfer curve and therefore the PES sensing noise (Ho and Doan, 1997;.…”

Section: Introductionmentioning

confidence: 99%

Measurement and modelling of disturbances in a servo track writer and advanced loop shaping to achieve higher track density

Zhang

Jiang

2009

Transactions of the Institute of Measurement and Control

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In this paper we present the idea of hybrid servo track writing and give a complete description of the developed hybrid servo track writer platform including its main functions and servo mechanism. The major disturbances and noise level in media-level servo track writing are identified based on the position error signal measured on the hybrid servo track writer platform. A dual-stage servo system, which is applicable in servo writing, is proposed and implemented on the experimental platform. With the disturbances and noise models, an advanced loop-shaping scheme based on Kalman—Yakubovic—Popov lemma is used to optimize the controller for the micro-actuator servo loop. The experimental results show that the tracking accuracy can reach 6 nm, which is able to support a track density of more than 400 000 tracks per inch.

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Section: Introductionmentioning

confidence: 99%

Measurement and modelling of disturbances in a servo track writer and advanced loop shaping to achieve higher track density

Zhang

Jiang

2009

Transactions of the Institute of Measurement and Control

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“…The detailed null burst pattern is shown in Figure 5 in [176]. Patent by Nazarian et al [172] shows a method to measure the burst nonlinearity and construct the correction values.…”

Section: Introductionmentioning

confidence: 99%

Servo pattern enhancements for high areal density hard disk drives

Kun¹

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The growth of areal density (AD) in hard disk drive (HDD), which measures the data bits per unit area, has slowed down considerably in recent years from the average of 30% annual increase rate achieved in past decades. The main reason is that the current perpendicular magnetic recording (PMR) technology has reached its bottleneck of the so-called superparamagnetism. In the meantime, HDD is facing a strong competition and high market share challenge from solid state drive (SSD). As a result, HDD industry is striving to improve the AD with a few technologies such as shingled magnetic recording (SMR), two-dimensional magnetic recording (TDMR), heat-assisted magnetic recording (HAMR) and bit patterned media (BPM). Among all of these, HAMR is the most viable and promising technology to bring the AD beyond a few terabyte/in 2 level in the coming decade. When the AD is > 1 terabyte/in 2 , the track width is expected to be smaller than a few tens of nanometers. Being a mechanical device, ever decreasing track width has imposed more stringent requirements on the servo system for the better track-following performance of read and write operations. This thesis first focuses on writing good quality servo patterns such as burst field and repeatable run-out (RRO) compensation field under HAMR writing conditions. The HAMR writing mechanism is fundamentally different from the PMR. For PMR, the written-in signal quality is mainly determined by the strength and the gradient of the writing magnetic field. However, for HAMR, although the writing magnetic field is important, the dominating factor for recording quality is determined by the media thermal profile. The media thermal profile is in turn determined by the thermal properties of the media stack and the thermal power delivered to the media. Given the write head design, and especially the near field transducer (NFT), the thermal power delivered to the media can be controlled through input laser power and the spacing between the NFT and the media. Unfortunately, the NFT-to-media

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Adaptive compensation for position error signal nonlinearity

Cooper

Hampshire²

2002

IEEE Trans. Magn.

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Distortion effects on servo position error transfer function

Cited by 4 publications

References 4 publications

Measurement and modelling of disturbances in a servo track writer and advanced loop shaping to achieve higher track density

Measurement and modelling of disturbances in a servo track writer and advanced loop shaping to achieve higher track density

Servo pattern enhancements for high areal density hard disk drives

Adaptive compensation for position error signal nonlinearity

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