Patents Represented by Attorney, Agent or Law Firm Mark A. Hillingsworth
  • Patent number: 6417982
    Abstract: A method and apparatus for identifying and filtering a resonance frequency of a support structure supporting a read/write head in proximity with a data storage medium involves obtaining a particular sample of a position error signal (PES) frequency transform, preferably using Goertzel's algorithm. The velocity of the data storage medium is varied, and the magnitude of a particular PES frequency transform sample is computed at each of the velocities. A resonance frequency of the support structure is calculated using the velocity associated with the particular sample having a maximum magnitude. The effects of one or more resonance frequencies associated with a read/write head suspension may be canceled in a position error signal using one or more programmable filters provided in each servo loop. A processor programs the filters using the calculated resonance frequencies and adjusts to compensate for the additional lag introduced into the respective servo loops by the selected programmable filters.
    Type: Grant
    Filed: December 2, 1998
    Date of Patent: July 9, 2002
    Assignee: International Business Machines Corporation
    Inventors: Hal Hjalmar Ottesen, Gordon James Smith