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Bias Compensation for Direct Access Storage Devices with Magnetic Actuator Latch

IP.com Disclosure Number: IPCOM000113712D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Eddy, KK: AUTHOR [+4]

Abstract

Compensation for nonlinear bias force in Direct Access Storage Devices (DASD) with a magnetic actuator lock is described. The bias force compensation method improves settle performance, and can tolerate variation in the magnetic latch strength.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 53% of the total text.

Bias Compensation for Direct Access Storage Devices with Magnetic
Actuator Latch

      Compensation for nonlinear bias force in Direct Access Storage
Devices (DASD) with a magnetic actuator lock is described.  The bias
force compensation method improves settle performance, and can
tolerate variation in the magnetic latch strength.

      Actuator control system bias force, resulting from a
combination of sources including flex cable spring force and actuator
driver electronics current offsets, varies as a function of actuator
position, temperature, and other effects.  The servo controller
seek/settle performance can be improved by accurately compensating
for bias force expected at the target (settle) cylinder through
matching the controller's integrator steady-state value at the same
cylinder.  The integrator is preloaded with the bias force prior to
settling on the target track.  This results in a smoother settle
response by reducing the dynamic effects induced when the integrator
charges to match the bias at the target track.

      Increasingly higher density track pitch necessitates greater
accuracy for the integrator bias preload.  Until the introduction of
a magnetic actuator latch, the bias force was approximately linear.

      The method used to identify the bias force involves capturing
integrated position values at various locations across the servo
surface, and is performed at power-up and periodically thereafter.
The actuator is movee to si...