Seagate Technology Incorporated

Bin Huang

Wenzhong Zhu

Kenneth A Haapala

Raye Abdoulie Sosseh

Tzung-Sz Shen

Ying Qi

Jason Wayne Riddering

Jeffrey Vincent DeRosa

Dustin Mark Cvancara

Gary Ernest Hillukka

Peng Yan

Eric John McCalla

Chiyun Xia

John Lowell Zeller

Implementations disclosed herein include a method to synthesize the controller of a multi-stage servo control system with multiple actuators in a hard disk drive by dividing controller synthesis into multiple dual-stage steps. The method includes measuring a first output of a first plant corresponding to a first actuator, measuring a second output of a second plant corresponding to a second actuator, designing a first controller responsive to the first output, designing a second controller responsive to the second output, and combining the first output and the second output to obtain a first combined output in a first dual-stage. The method also includes designing a third controller responsive to the first combined output, measuring a third output from a third plant corresponding to a third actuator, designing a fourth controller responsive to the third output, and combining the first combined output and the third output to obtain a second combined output.

Multi-stage servo control design system

A clearance heater of a write head is engaged with a boosted current that exceeds a steady-state current. The steady-state current causes the write head to maintain a desired clearance over a disk during writing, the boosted current being applied before a start of the writing. The boosted current is monotonically decreased before the start of the writing and the steady-state current is applied to the heater after the start of the writing.

Boosted preheat trajectory to obtain desired clearance before writing to disk

Systems and methods for determining a relationship between write fault threshold and temperature are described. The systems and methods include measuring an operating temperature of the storage device, determining a current operating temperature of the storage device, determining whether the current operating temperature of the storage device satisfies a temperature threshold, and upon determining the current operating temperature of the storage device satisfies the temperature threshold, modifying a write fault threshold associated with a data track of the storage device.

Adaptive write fault thresholds

A system may compensate for skew in a patterned medium, such as but not limited to a self-assembling bit patterned medium, with a write pole separated from a data storage medium by an air bearing. The write pole being connected to a controller. The data storage medium can have a plurality of magnetic islands arranged in data tracks with each data track having a track center. The write pole may be selectively shifted from the track center by the controller to compensate for a skewed write pole configuration.

Skew compensation in a patterned medium

A plurality of sensors are used to sense disturbances in a data storage system. An adaptive gain component is associated with each of the sensors and provides a gain for each of the sensor signals. The gain of each sensor signal is adapted, individually, based on a correlation of each given sensor signal to the position error signal. This adaptation produces a position correction signal. The position correction signal is applied to a position signal that is used to position the reading and writing components and the storage medium relative to one another. This compensates for both rotary and linear vibration disturbances at the same time.

Compensation for vibration in a data storage system

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Savage, MN, United States of America

Bin Huang