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# Compensation Algorithm for Disturbance in Hard Disk Servo System

IP.com Disclosure Number: IPCOM000099293D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 63K

IBM

## Related People

Arai, K: AUTHOR [+1]

## Abstract

Disclosed is an algorithm which compensates a disturbance in a hard disk drive servo system. function is achieved by software (microprocessor). function is divided mainly into two portions. One is a measuring function of the stationary the other portion is a compensating function it. The feature of this function is described as 1) The integrated value of the position error signals is used for the measurement of the disturbance. 2) This measurement is done at several points equally distributed within the whole cylinder range. 3) An offset table whose value balances the stationary disturbance is made for each measuring point. 4) The compensation is done by adding the offset value to the servo control output value.

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Compensation Algorithm for Disturbance in Hard Disk Servo System

Disclosed is an algorithm which compensates a disturbance
in a hard disk drive servo system. function is achieved by software
(microprocessor). function is divided mainly into two portions.  One
is a measuring function of the stationary the other portion is a
compensating function it.  The feature of this function is described
as
1)   The integrated value of the position error signals
is used for the measurement of the disturbance.
2)   This measurement is done at several points equally
distributed within the whole cylinder range.
3)   An offset table whose value balances the
stationary disturbance is made for each measuring
point.
4)   The compensation is done by adding the offset
value to the servo control output value.

a)   The measurement of the stationary  The stationary
disturbance is for example, by a tension of a cable, an offset of a
digital/ converter and so on.  To measure these integration of the
position error (pes) value is used.  Equation (1) a servo control
law. In this equation, amount of the first term which is the of pes
is proportional to the  at the stationary state.  Thus, is done by
minimizing this by adding the offset to the servo value.  Thus,
measurement is at a power-on reset of the hard drive and at several
points of the cylinder range, and the offs...