Browse Prior Art Database

Automated Custom Tuning Servo System for Hard File Manufacturing

IP.com Disclosure Number: IPCOM000099467D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 82K

Publishing Venue

IBM

Related People

Fiechtner, GE: AUTHOR [+5]

Abstract

Disclosed is a servo system architecture for a direct access storage device which provides for custom tuning of its digital servo system for each individual head and disk assembly. This system is used to reduce the effects of manufacturing part tolerances on servo performance by being able to tune the servo system to account for gain and resonance variation. Automated test equipment is used to implement this custom tuning process on the manufacturing line.

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Automated Custom Tuning Servo System for Hard File Manufacturing

       Disclosed is a servo system architecture for a direct
access storage device which provides for custom tuning of its digital
servo system for each individual head and disk assembly.  This system
is used to reduce the effects of manufacturing part tolerances on
servo performance by being able to tune the servo system to account
for gain and resonance variation.  Automated test equipment is used
to implement this custom tuning process on the manufacturing line.

      A servo system using this tuning method operates as follows.
Only a low performance and simple servo control algorithm would be
stored on the electronics card in a PROM module.  This code serves a
boot-strap function of being able to find a reserved area on the disk
file and read in the high performance product servo code.  The
advantage of storing the actual product servo code on the disk file
allows for customization of code with no hardware change to the
electronics.  This allows flexibility in the servo system without
requiring new PROM modules to be placed on the electronics card and
provides the ability to easily alter the servo microprocessor code in
product development and in manufacturing.

      The boot-strap code also includes a simple track follow mode.
During manufacturing, it operates as the closed loop controller while
a mechanical transfer function analysis test is performed on the
head-to- disk assembly.  This is to characterize the gain and phase
transfer function between input current to the actuator and the
position error feedback.  The transfer function analysis (TFA) is
performed by a tester that injects a noise signal into the system and
measures the frequency response.

      To implement automated custom servo tuning, a computer takes
mechanical transfer function analysis data and generates the optimum
servo code for that head and disk assembly.  This generated high
performance product code is then sent through...