Western Digital Technologies, Inc.

Hitachi, Ltd.

Hitachi Global Storage Technologies Japan, Ltd.

Hitachi Global Storage Technologies Netherlands B.v.

Hidehiko Numasato

Masahito Kobayashi

Takashi Yamaguchi

Shrey Khanna

Hiroshi Uchida

Katsuhiro Tsuneta

Shinsuke Nakagawa

Yosuke Hamada

Yoshikatsu Fujii

Tsuyoshi Arai

Katsumoto Onoyama

Kexiu Liu

Atsushi Okuyama

Zaifeng Chen

Shigeo Nakamura

Tetsuo Semba

Jianguo Zhou

Takenori Atsumi

Marutomo Goto

Kevin Tzou

Masaki Odai

Kei Yasuna

Jiro Abe

Yoshio Soyama

Peyman Niazi

Feng Hong

Akira Yokozuka

Various illustrative aspects are directed to a data storage device, method, and one or more processing devices that are configured to: select a seek time model from a plurality of seek time models based at least in part on an operational characteristic of an access command, the operational characteristic relating to an off-track susceptibility of executing the access command; determine an access time for the access command using the selected seek time model; and select a next access command for execution based on the determined access time for the access command and determined access times for other ones of a plurality of access commands.

Data storage device sorting access commands based on performance and off-track mitigation optimization

A Data Storage Device (DSD) includes a disk to store data, at least one head to read and write data on the disk, and a Voice Coil Motor (VCM) to move the at least one head over the disk. An upper velocity limit is reduced for moving the at least one head to perform a command to read or write data at a target location on the disk as a precautionary measure against damaging the at least one head during an Emergency Power Off (EPO) state. The upper velocity limit is reduced in response to the target location being in an Outer Diameter (OD) region of the disk, a direction needed to move the at least one head being in an Inner Diameter (ID) to OD direction, and a starting position being at least as radially far from an OD region position as a predetermined threshold.

Head velocity derating for data storage devices including disk media

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The one or more processing devices are configured to: output a multi-rate excitation to at least one multi-rate notch filter of the actuator mechanism control system; detect a frequency response of the actuator mechanism in response to the multi-rate excitation; and calibrate the at least one multi-rate notch filter of the actuator mechanism control system, based at least in part on the detected frequency response of the actuator mechanism.

Data storage device with notch filter calibration based on multi-rate excitation and error rejection

Various illustrative aspects are directed to a data storage device, comprising one or more disks; an actuator mechanism configured to position one or more heads proximate to one or more disk surfaces of the one or more disks; and one or more processing devices, comprising an actuator mechanism control system configured for controlling the actuator mechanism. The processing devices are configured to: apply coefficients for a multi-rate notch filter to a servo control loop; measure a multi-rate error rejection transfer function; determine whether a peak of the multi-rate error rejection transfer function is greater than a multi-rate error rejection transfer function threshold; and modify, responsively to determining that the peak of the multi-rate error rejection transfer function is not greater than the multi-rate error rejection transfer function threshold, the parameters of the multi-rate notch filter based at least in part on the peak of the multi-rate error rejection transfer function.

A data storage device comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configured to actuate a second head over a second disk surface. A plurality of access commands are received from a host, and a cost metric is computed for executing a seek to execute each access command of the plurality of access commands, wherein the cost metric is based on an access latency of the seek, a power consumption of the seek, and an estimated combined current draw of the first and second actuators during the seek. The access commands are sorted into an execution order based on the cost metrics computed for the access commands.

Data storage device sorting access commands based on peak current for multiple actuators

A data storage device is disclosed comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configure to actuate a second head over a second disk surface. A first seek of the first head over the first disk surface is initiated during a first seek time based on a first seek profile. A second seek of the second head over the second disk surface is initiated during a second seek time based on a second seek profile. When the second seek time at least partially overlaps the first seek time and at least the second seek profile is a de-rated seek profile, the second seek profile is adjusted to avoid an overcurrent condition.

Data storage device managing peak current for multiple actuators

A data storage device is disclosed comprising a first actuator configured to actuate a first head over a first disk surface, and a second actuator configured to actuate a second head over a second disk surface. A seeking control signal is generated and used to control the first actuator to seek the first head over the first disk surface. The seeking control signal is filtered with a decoupler to generate a decoupler control signal, wherein the decoupler comprises a nominal decoupler and an adaptive decoupler. A tracking control signal is generated based on the decoupler control signal, and the tracking control signal is used to control the second actuator in order to access the second disk surface using the second head.

Data storage device employing nominal and adaptive multi-actuator decoupler

In one embodiment, a magnetic disk apparatus comprises a magnetic disk for recording information; a magnetic head that reads information from, or writes information to, the magnetic disk; an actuator device that drives the magnetic head; and a control system that controls the driving of the actuator device. The actuator device is configured by a dual stage actuator comprising a fine actuator that drives the head and a coarse actuator that drives the magnetic head together with the fine actuator. The control system includes a fine controller that generates an operational value for driving the fine actuator and a coarse controller that generates an operational amount for driving the coarse actuator. The control system includes a mechanism for smoothly changing the operational amount generated by the fine controller immediately before saturation resulting from an applied voltage limit of the fine actuator or at the time the fine actuator returns to a control range from the saturation.

Magnetic disk apparatus with dual stage actuator

A seek controller corresponds to a velocity control system which produces a target value based upon a target track, a present position, and a remaining distance from a commencement of a seek operation up to a time instant when a sign of an operating amount is changed; and the seek controller corresponds to a Two Degree of Freedom control system which sets an waveform by a function of time as a target value after the time instant when the sign of the operating amount is changed. The hard disk drives applies a velocity control system based upon a deviation of head positions as to a VCM voltage saturation and a uniform velocity mode, and also, applies a Two Degree of Freedom control system with employment of a function of time having a smooth locus in a decelerated velocity mode so as to suppress residual vibrations.

Magnetic disk apparatus

In a positioning control device for a two-stage actuator having a coarse-movement actuator and a fine-movement actuator, a notch filter having a cutoff frequency fn is provided to a coarse-movement control loop, and the fine-movement actuator is driven by a sine wave of the frequency fn. At the frequency fn, a head position signal becomes identical with an output signal of the fine-movement actuator, by which the gain of the fine-movement actuator can be estimated by an adaptive identification unit with high accuracy based on the control input to the fine-movement actuator and the head position signal.

Positioning control device for two-stage actuator

The magnetic disk apparatus includes a magnetic disk for storing thereinto information; a head equipped with a recording conversion element for writing information into the magnetic disk and a reproducing conversion element for reading information from the magnetic disk; an actuator arranged by a suspension for supporting the head so as to move the head on the magnetic disk, and also a drive apparatus for driving the suspension; and a stopper for limiting a movable range of the actuator, whereby a distance between a reproduction element and a recording element is measured and also a track width of the magnetic disk is measured in order to execute a self-servo write operation.

Magnetic disk apparatus and servo signal recording method

A magnetic disk device comprises at least a disk having information, at least a head for reading or writing information from or into the disk, at least a micro actuator for supporting the head and positioning the head, a coarse actuator for carrying the micro actuator and positioning the head, a controller for controlling the micro actuator and the coarse actuator based on the servo information read by the head, and a host controller for determining that information is to be read. In the case where the host controller determines that the operation is in a wait mode, the positioning operation of the micro actuator is stopped.

Magnetic disk device including coarse and micro actuators

A sector servo type magnetic disk apparatus is provided with, in addition to servo signals, a sensor such as an accelerometer for detecting a state of a magnetic head or a support for the magnetic head at a period shorter than a sampling period of the servo signals. Since an accelerometer mounted on the magnetic head or the support for the magnetic head detects an acceleration, the control performance of a servo control system can be improved, such as reduction of generation of mechanism resonance vibrations of a carriage and improvement on detection precision of a speed signal.

Magnetic disk apparatus having an accelerometer for detecting acceleration in the positioning direction of the magnetic head

An apparatus for positioning a magnetic head includes a servo signal detection circuit for detecting a servo signal recorded on a magnetic disk in a predetermined first period, an acceleration measuring portion which is fitted to a part of a mechanism for mounting a magnetic head, outputs an acceleration signal in a direction of positioning the magnetic head, and samples the acceleration signal in a second period shorter than the first period, a comparison processing portion for comparing a deviation value computed from at least either one of the acceleration signal and the servo signal with a predetermined value, a write inhibit signal generating portion for generating a signal inhibiting write of data on a magnetic disk in accordance with the result of comparison in the comparison processing portion, and a manipulated variable compensation portion for generating manipulated variable for adjusting the position of the magnetic head from at least either one of the servo signal and the acceleration signal and a target value of the position of the magnetic head, whereby to prevent erroneous write operation of data onto a magnetic disk due to unsteady positioning error of the magnetic head.

Growing community of inventors

Odawara, Japan

Hidehiko Numasato