Browse Prior Art Database

Adaptive Seek Control of a Disk Drive

IP.com Disclosure Number: IPCOM000105060D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 87K

Publishing Venue

IBM

Related People

Semba, T: AUTHOR

Abstract

Method for track-access of a disk drive is described that achieves fast access even when the gain of an actuator changes by the temperature dependency or the variation among individuals.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Adaptive Seek Control of a Disk Drive

      Method for track-access of a disk drive is described that
achieves fast access even when the gain of an actuator changes by the
temperature dependency or the variation among individuals.

      The embodiment of the invention is explained with reference to
the figure.  In general, to end a track access on a target track
securely, the absolute value of acceleration of the  actuator at the
time of deceleration is set to a value that is smaller than the
nominal maximum acceleration.  This margin is determined by taking
account of the disturbance applied to the actuator, the reduction of
the drive force by the temperature dependency of the actuator gain,
variation among individual actuators in maximum acceleration, and
other factors.  For example, if the variation among individual
actuators in maximum acceleration is 5G  10% and the fluctuation
according to temperature dependency is  10%, the maximum
acceleration of the actuator will be 4G (G stands for gravitational
acceleration) in the worst-case scenario.  Furthermore, if it is
assumed that the disturbance is 0.5G, a reference velocity and other
values must be set so that the acceleration will be 3.5G or less.
Even if a certain individual actuator can have an acceleration of 6G
at a certain point, the time required for track access will not be
improved, because control is performed at a reference velocity that
is set low.  At present, therefore, the reference velocity and other
values must be set so that the gain of an actuator varies, and the
smaller the maximum acceleration is, the longer the track access time
is.  In other words, in order to shorten the track access time, the
variation in the gain of individual actuators and the fluctuation
according to temperature dependency have to be made small, making it
difficult to design an actuator.

      Therefore, this invention allows high-speed access, even if
there is a fluctuation in the gain of actuator 26, by adding
averaging device 70 and comparator 72 to the conventional servo
controller and by enabling the gain of integrator 40 to be varied by
output signal 104 of comparator 72.  More specifically, signal 96,
which actually drives actuator 26, is supplied by an...