Mirmehdi L Abrishamchian

7224543, May 29, 2007

Jun 4, 2004

10/861101

Mirmehdi L. Abrishamchian - Shrewsbury MA, US
Orhan Beker - Shrewsbury MA, US
Kevin Blankespoor - Framingham MA, US

Maxtor Corporation - Scotts Valley CA

G11B 15/04

360 60

The present invention is directed to a method and apparatus for reducing off-track writes in a data storage device. In one embodiment, a command is received to perform a write operation using a write head at a first location on a disk surface. A determination is made as to whether to perform or inhibit the write operation using an equation having a tunable acceleration coefficient. The equation is used to predict a position error signal (PES) value for a write head at a servo sector that immediately circumferentially follows the first location (i. e. , there are no intervening servo sectors between the servo sector and the first location). If the predicted PES value is outside of (e. g. , greater than or less than) a predetermined threshold, an off-track write is likely to occur and the write operation is inhibited.

7489472, Feb 10, 2009

Jan 24, 2007

11/657161

Mirmehdi L. Abrishamchian - Shrewsbury MA, US
Travis Hein - Holliston MA, US
Jihao Luo - Shrewsbury MA, US

Maxtor Corporation - Longmont CO

G11B 5/596

360 7809, 360 7804

A method of providing a control output by selecting a controller to an actuator is discussed. A first controller having an estimator-compensator architecture is selected if the actuator is in a settle stage. A second controller having an architecture other than that of the first controller is selected when the actuator is in a track follow stage. The control output is provided from the selected controller to the actuator. The control output is indicative of the control signal.

7602572, Oct 13, 2009

Feb 21, 2007

11/709184

Mirmehdi L. Abrishamchian - Shrewsbury MA, US
Travis Hein - Holliston MA, US

Seagate Technology LLC - Scotts Valley CA

G11B 5/596
G11B 21/02

360 75

Adjusting a servo control system includes identifying a gain crossover frequency for the servo control system, generating a sensitivity function for the servo control system, measuring a sensitivity peak in the sensitivity function, comparing a frequency of the sensitivity peak to the gain crossover frequency, and adjusting the servo control system in response to the comparison of the frequency of the sensitivity peak to the gain crossover frequency.

20020012191, Jan 31, 2002

Jun 8, 2001

09/877053

Hai Ho - Broomfield CO, US
Justin Won - Longmont CO, US
Mirmehdi Abrishamchian - Marlborough MA, US
Gregory Campbell - Lyons CO, US

SEAGATE TECHNOLOGY LLC

G11B027/36
G11B005/596

360/077040, 360/077080, 360/031000

An apparatus and method for compensating repeated runout position error in a disc drive data handling system having an actuator assembly which supports a head adjacent a recording surface. A servo loop generates a position error signal (PES) to control the position of the head. A digital filter is configured to place a notch in an error sensitivity function relating the PES to the repeated runout position error, with the notch being nominally centered at a frequency of rotation of the recording surface. The filter thereafter filters the PES to generate compensation signals that are injected into the servo loop. At least selected filter parameters are determined by measuring the frequency response of the servo loop and used as a priori knowledge to produce a loop matching effect that results in a consistent convergence rate for any targeted frequency to be filtered.

20080159105, Jul 3, 2008

Dec 28, 2006

11/617522

Hemmant Gopal - Newton MA, US
Bijan Tehrani - Shrewsbury MA, US
David J. Kaphammer - Lyons CO, US
Mirmehdi L. Abrishamchian - Shrewsbury MA, US

SEAGATE TECHNOLOGY LLC - Scotts Valley CA

G11B 20/18

369 5343

Systems and methods are disclosed for detecting spindle motor degradation. A method includes issuing an alert if a difference between feed forward compensation signals of repeatable runout determined at a first time and feed forward compensation signals of repeatable runout determined at a second time satisfies a first threshold condition. A method may further include issuing an alert if a delta difference between a first difference and a second difference satisfies a second threshold condition. The first difference represents a difference between the feed forward compensation signals of repeatable runout at the first time and the feed forward compensation signals of repeatable runout at the second time. The second difference represents a difference between the feed forward compensation signals of repeatable runout at the first time and feed forward compensation signals of repeatable runout at a third time.