Browse Prior Art Database

Dynamic Adaptive Veolcity Profile for Direct Access Storage Devices

IP.com Disclosure Number: IPCOM000106409D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Kittilson, GB: AUTHOR [+3]

Abstract

A method for direct access storage device (DASD) coil warm-up compensation is disclosed. Dynamic adaptation of a fixed velocity profile is achieved by detecting a change in coil resistivity through monitoring requested coil current.

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Dynamic Adaptive Veolcity Profile for Direct Access Storage Devices

      A method for direct access storage device (DASD) coil warm-up
compensation is disclosed.  Dynamic adaptation of a fixed velocity
profile is achieved by detecting a change in coil resistivity through
monitoring requested coil current.

      A great deal of power is used in moving the actuator and much
of this is dissipated as heat in the voice coil.  Each access results
in current applied to the voice coil on the actuator.  The access
rate determines the average coil current, which affects voice coil
resistivity.

      A velocity profile is used during arrival on a target track to
provide a controlled velocity as a function of distance to the target
track.  The difference between the velocity profile and the actual
velocity is used to determine the amount of requested coil current.
A single velocity profile is developed for a known coil resistance.
However, if the coil resistance or supply voltage changes
dynamically, the velocity profile is no longer able to provide
reliable access control during the arrival (deceleration) portion of
the seek.  The difference between the velocity profile and the actual
velocity has increased resulting in greater requested coil current
or, better termed, excessive arrival current.

      The excessive arrival current is detected and used to reduce a
velocity profile by an adjustment factor, (Figure).  Each time
excessive arrival current is detec...