Patents by Inventor Mirmehdi L. Abrishamchian
Mirmehdi L. Abrishamchian has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 9275667Abstract: A disk drive has a servo control system that implements just-in-time (JIT) seeks with low power consumption for all long seeks. The servo controller receives a seek command to move the transducer to a target data track and sector, calculates rotational latency from the seek command, and limits the transducer velocity for seeks longer than a predetermined seek length. The servo controller then generates a JIT gain from the calculated rotational latency, modifies the transducer acceleration and deceleration using the JIT gain, and modifies the transducer velocity limit using the JIT gain. Positive current is applied to the actuator to move the transducer with the JIT gain-modified acceleration until the transducer reaches the modified velocity limit. The servo controller determines when to initiate deceleration of the transducer, and applies negative current to the actuator to move the transducer with the JIT gain-modified deceleration until the transducer reaches the target track.Type: GrantFiled: January 22, 2015Date of Patent: March 1, 2016Assignee: HGST Netherlands B.V.Inventors: MirMehdi L. Abrishamchian, Fred Feng Hong, Peyman Niazi
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Patent number: 7602572Abstract: 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.Type: GrantFiled: February 21, 2007Date of Patent: October 13, 2009Assignee: Seagate Technology LLCInventors: Mirmehdi L. Abrishamchian, Travis Hein
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Patent number: 7489472Abstract: 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.Type: GrantFiled: January 24, 2007Date of Patent: February 10, 2009Assignee: Maxtor CorporationInventors: Mirmehdi L. Abrishamchian, Travis Hein, Jihao Luo
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Publication number: 20080174900Abstract: 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.Type: ApplicationFiled: January 24, 2007Publication date: July 24, 2008Applicant: Maxtor CorporationInventors: Mirmehdi L. Abrishamchian, Travis Hein, Jihao Luo
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Publication number: 20080159105Abstract: 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.Type: ApplicationFiled: December 28, 2006Publication date: July 3, 2008Applicant: SEAGATE TECHNOLOGY LLCInventors: Hemmant Gopal, Bijan Tehrani, David J. Kaphammer, Mirmehdi L. Abrishamchian
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Publication number: 20070268797Abstract: 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.Type: ApplicationFiled: February 21, 2007Publication date: November 22, 2007Inventors: Mirmehdi L. Abrishamchian, Travis Hein
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Patent number: 7224543Abstract: 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.Type: GrantFiled: June 4, 2004Date of Patent: May 29, 2007Assignee: Maxtor CorporationInventors: Mirmehdi L. Abrishamchian, Orhan Beker, Kevin Blankespoor
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Patent number: 6819521Abstract: 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.Type: GrantFiled: June 8, 2001Date of Patent: November 16, 2004Assignee: Seagate Technology LLCInventors: Hai T. Ho, Justin Won, Mirmehdi L. Abrishamchian, Gregory A. Campbell
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Publication number: 20020012191Abstract: 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.Type: ApplicationFiled: June 8, 2001Publication date: January 31, 2002Applicant: SEAGATE TECHNOLOGY LLCInventors: Hai T. Ho, Justin Won, Mirmehdi L. Abrishamchian, Gregory A. Campbell