Browse Prior Art Database

Sweep Down Method of Torque Amplification for Stiction

IP.com Disclosure Number: IPCOM000117959D
Original Publication Date: 1996-Jul-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 61K

Publishing Venue

IBM

Related People

Khanna, V: AUTHOR [+7]

Abstract

Hard Disk Drives (HDDs) fail to spin up due to excessive stiction between the slider and disk. 'Torque Amplification' is a microcode based procedure that is executed when the HDDs fail to start up normally. It is a complex that is used to drive the spindle motor in order to amplify the available torque via mechanical resonances.

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Sweep Down Method of Torque Amplification for Stiction

      Hard Disk Drives (HDDs) fail to spin up due to excessive
stiction between the slider and disk.  'Torque Amplification' is a
microcode based procedure that is executed when the HDDs fail to
start up normally.  It is a complex that is used to drive the spindle
motor in order to amplify the available torque via mechanical
resonances.

      There is one issue that can cause serious problems...the
present torque amplification algorithm uses a sweep-up method for
sweeping through it's range of frequencies.  Consider the case where
there are multipile sliders stuck to the disk.  The algorithm will
have to sweep the motor to a correspondingly high frequency before it
can excite the resonance, hence, the amplification that is needed to
overcome stiction.  There is the finite possibility that all the
stuck sliders will not break free at the same time.  In which case,
as the first slider breaks free, the resonance frequency of the
system and the remaining stuck sliders will suddenly drop to a lower
value.  The excitation frequency will then be higher or past that
resonance and subsequent execution of the algorithm will only push it
further away.  There will be no way to break free the remaining
sliders in that sweep.  Since subsequent sweeps will be needed to
break free the remaining sliders, the time needed to successfully
execute the algorithm will be greatly increased.  Then there is the
chance of a sli...