Patents by Inventor Edgar De-Jia Sheh

Edgar De-Jia Sheh 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).

  • Patent number: 6204988
    Abstract: The invention is a method of characterizing the frequency response of the servo control system in a disk drive having a sampled servo system having a sampling rate and a nominal bandwidth, wherein the sampled servo system comprises a plant and a servo controller that controls the plant using a compensator and a gain element with a nominal open loop gain. The invention is, in more detail, a method for adaptively modifying the servo controller to compensate for plant variations which are incompatible with the nominal gain and bandwidth, including the steps of implementing a self-generated bode plot to determine a gain margin and a phase margin, and if the gain margin is not greater than a predetermined minimum, adjusting the open loop gain of the servo controller to provide a gain margin which is greater than the predetermined minimum at a bandwidth which is different than the nominal bandwidth; and adjusting the compensator to provide a phase margin which is greater than a predetermined minimum.
    Type: Grant
    Filed: August 24, 1998
    Date of Patent: March 20, 2001
    Assignee: Western Digital Corporation
    Inventors: Raffi Codilian, Edgar De-Jia Sheh, Jie Yu