Browse Prior Art Database

Track Follow Integrator Pre-Charge Prediction Utilizing an Averaged Integrator Value

IP.com Disclosure Number: IPCOM000115099D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 75K

Publishing Venue

IBM

Related People

Blank, TJ: AUTHOR [+2]

Abstract

A method to improve the seek/settle performance in disk drives by calculating an integrator pre-charge value from an averaged value of the integrator state is described. Utilizing the averaged integrator value instead of an instantaneous value as the means for the integrator pre-charge calculation improves the settle performance capability in the presence of disk runout.

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Track Follow Integrator Pre-Charge Prediction Utilizing an Averaged
Integrator Value

      A method to improve the seek/settle performance in disk drives
by calculating an integrator pre-charge value from an averaged value
of the integrator state is described.  Utilizing the averaged
integrator value instead of an instantaneous value as the means for
the integrator pre-charge calculation improves the settle performance
capability in the presence of disk runout.

      Bias force mapping is often used as a basis for the means to
improve the seek/settle performance in disk drives.  Bias force
mapping is accomplished by measuring the averaged integrator state
value in at least two reference locations such that the integrator
value can be computed for all of the other locations.  Due to certain
factors, such as thermal drift, the bias forces can change over time,
hence the mapping is usually updated periodically.  However, even
though the absolute values of the bias forces may change, the slope
of the line computed by the mapping does not change significantly.

      Until now, the integrator pre-charge calculation that is made
just prior to a seek operation was performed based on a function of
the current integrator value and the slope of the bias force line
determined by previous bias force mapping.  This calculation was used
to pre-charge the integrator value for the seek target location to
reduce the seek to settle mode hand-off transients.  However, as disk
drive track densities increase, the effects of disk runout also
increase, in terms of producing substantial errors in the integrator
pre-charge prediction computation.  This can lead to significantly
larger settle response transients and poorer settle performance.

      The Figure illustrates the ben...