Seagate Technology Incorporated

Xiang Lu

Xiong Liu

Qiang Bi

MingZhong Ding

KianKeong Ooi

Kian Keong Ooi

Lihong Zhang

GuoQing Zhang

Chan Fan Lau

Hoang Dung Vu

Jin Quan Shen

Lou Supino

JiaHong Shu

WenJun Cao

Hui Wang

A device includes a servo controller that includes or that is coupled to memory. The memory stores multiple distinct disturbance control schemes. The servo controller is configured to select and implement one of the disturbance control schemes in response to receiving a command from a host. The servo controller can be implemented on a system on a chip.

Adaptable servo controllers

Gain values used by a variable gain amplifier (VGA) to read servo marks of a heat-assisted recording medium are measured. Sector-specific, repeatable gain values that indicate an expected VGA gain at a desired clearance are determined based on the measured gain values. The sector-specific, repeatable gain values are used as input to a closed-loop clearance controller together with measured values of servo VGA gain while writing data to the recording medium.

Closed-loop fly height control using transfer function between harmonic response and heater input

Systems and methods for compensating for magnetoresistive (MR) jog offset direct current (DC) drift in a disc drive are described. In one embodiment, a method may include determining an occurrence of NOS, for example, by monitoring disc slip, to determine when the method should proceed. An MR jog offset DC drift amount is determined for each head of the disc drive. One of several approaches may be employed for determining the MR jog offset DC drift amount. By determining an MR jog offset DC drift amount for each head, a compensation profile is determined for the drive. The determined compensation profile may then be used during operation of the disc drive to compensate for the DC drift. One of several approaches may be employed for compensating based on the compensation profile.

Direct current magnetoresistive jog offset compensation

Closed-loop fly height control using sector-specific, repeatable VGA values

An apparatus includes a frequency analyzer circuitry, filter circuitry, and voice coil motor (VCM) control circuitry. The frequency analyzer circuitry is configured to detect one or more dominant frequencies of a position error signal (PES). The filter circuitry is configured to identify one or more filters in response to detecting the one or more dominant frequencies, apply the one or more identified filters to at least one of a microactuator control signal and PES, and generate a VCM compensation signal in response to the filtered PES or the microactuator control signal. The VCM control circuitry is configured to generate a VCM control signal in response to the VCM compensation signal.

Adaptive attenuation for disturbance compensation

An apparatus includes a microactuator controller configured to generate a microactuator control signal, a feedforward microactuator compensator configured to generate a microactuator compensation signal, and a microactuator model filter configured to filter a modified microactuator control signal. The microactuator compensation signal is configured to be injected into the microactuator control signal to generate the modified microactuator control signal. The microactuator model filter generates a filtered modified microactuator control signal and injects the filtered modified microactuator control signal into a position error signal to generate a modified position error signal.

Disturbance compensation for dual-stage servo system using vibration sensor

Technologies are described herein for temporarily writing data to a buffer zone on a recording medium of a storage device when the device is operating in a vibration condition. A vibration condition is detected in the storage device, and upon detecting the vibration condition, data of a current write operation is written to a buffer zone on a recording medium of the storage device, the buffer zone being configured with a lower areal density of storage than primary storage zones on the recording medium. At a later time, an idle condition may be detected in the device, and upon detecting the idle condition, it may be determined whether the vibration condition exists. If it is determined that the vibration condition no longer exists, the data is transferred from the buffer zone to the primary storage zones on the recording medium.

HDD write buffer zone for vibration condition

An apparatus includes a controller configured to be coupled to a read/write head. The controller is configured to perform various operations including detecting a change in a time interval difference between servo sectors of a servo marked recording medium, converting the change to an offset signal that compensates for the change, and positioning the read/write head relative to the servo mark recording medium in response to the offset signal. The change in the time interval difference is representative of disk slip.

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Singapore, Singapore

Xiang Lu