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Adaptive Kick Velocity for L/UL System

IP.com Disclosure Number: IPCOM000123752D
Original Publication Date: 1999-Apr-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Ogasawara, K: AUTHOR [+4]

Abstract

This article describes the algorithm to improve the reliability and design freedom of the Ramp Load/Unload System of HDD. The initial velocity of the Loading motion is one of the key design parameters . This velocity should be enough high to secure the start of the motion overcoming the static friction between the ramp and suspension. On the other hand, this should be enough low to prevent the head suspension jumping onto the disk surface. The velocity is determined by the Peak VCM current for the initial kick of the VCM at the very beginning of the loading motion, and the duration of the initial kick. But there are several factors which can affect to the "drive-to-drive" variation of the velocity.

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Adaptive Kick Velocity for L/UL System

   This article describes the algorithm to improve the
reliability and design freedom of the Ramp Load/Unload System of
HDD.  The initial velocity of the Loading motion is one of the key
design parameters . This velocity should be enough high to secure the
start of the motion overcoming the static friction between the ramp
and suspension.  On the other hand, this should be enough low to
prevent the head suspension jumping onto the disk surface.  The
velocity is determined by the Peak VCM current for the initial kick
of the VCM at the very beginning of the loading motion, and the
duration of the initial kick.  But there are several factors which
can affect to the "drive-to-drive" variation of the velocity.
  o  - Variation of the VCM magnet strength
  o  - Variation of the VCM driver module which affect to the
       VCM current
  o  - Variation of the static/dynamic friction of the Ramp
  o  - Variation of the support magnet strength which hold back
       the VCM Arm

   Those variations make the design freedom very limited,
and make the design optimization difficult.

   In order to solve those difficulties, an adaptive velocity
control is introduced here.  The adaptive algorithm is
  1.  Measure the Kick Velocity by using Back Emf from VCM.
  2.  Check the velocity if it exceed the High or Low boundary
      which is pre-determined criteria.
  3.  If it is within the criteria, the load sequence...