Browse Prior Art Database

Fast Settling Time for Hard Disk File

IP.com Disclosure Number: IPCOM000100092D
Original Publication Date: 1990-Mar-01
Included in the Prior Art Database: 2005-Mar-15
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Kisaka, M: AUTHOR

Abstract

Disclosed is an algorithm to get faster settling time for a hard disk file. A settling mode is usually used between a velocity-control mode and a track-following mode to achieve smooth trajectory. To get faster settling time, a new position error calculation in settling mode is described.

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Fast Settling Time for Hard Disk File

       Disclosed is an algorithm to get faster settling time for
a hard disk file.  A settling mode is usually used between a
velocity-control mode and a track-following mode to achieve smooth
trajectory.  To get faster settling time, a new position error
calculation in settling mode is described.

      Previous methods get a position error for the settling mode as
follows:
position error = current position - target position  (1)

      If stable poles are chosen for a closed-loop servo system, the
position error and velocity get small when the current position
approaches the target position.  That means the movement of an
actuator becomes slow near the target. Therefore, the settling time
gets long.

      By using the following position error in the settling mode,
instead of Eq. (1),
position error = current position - (target position + delta) (2)
where delta is chosen for an actuator to overshoot the target (Fig.
1).
The velocity of the actuator is not zero at the target position,
because the delta is chosen to overshoot the target.  If the delta is
chosen for the velocity to be within a certain range at the target
position, a faster settling time can be obtained.