Browse Prior Art Database

Multi-rate Controller Implementation for Sector Servo System

IP.com Disclosure Number: IPCOM000108657D
Original Publication Date: 1992-Jun-01
Included in the Prior Art Database: 2005-Mar-22
Document File: 1 page(s) / 41K

Publishing Venue

IBM

Related People

Chiang, WW: AUTHOR [+2]

Abstract

Disclosed is an improved algorithm to implement the multi-rate digital controller for disk drive actuators using the sector servo system. This algorithm has the advantage of reducing the real-time computational burden from the previously disclosed method.

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Multi-rate Controller Implementation for Sector Servo System

       Disclosed is an improved algorithm to implement the
multi-rate digital controller for disk drive actuators using the
sector servo system.  This algorithm has the advantage of reducing
the real-time computational burden from the previously disclosed
method.

      The previously disclosed method (*) needs to estimate all state
variables not only at the sector servo sample time but also in
between when the Voice Coil Motor (VCM) control current is computed
and updated.  The state estimator predicts the state variable values
in open-loop in between sector servo samples.  This method requires
that the state estimator be run as often as the VCM control, and thus
increases the computational burden by the same ratio which the VCM
control update rate is increased from the original sector servo
sample rate.

      Because all state variables are predicted in open-loop in
between sector servo measurements, and all VCM control currents are
calculated as linear combinations of estimated state variables, it
turns out that all VCM control currents in between consecutive sector
servo measurements can be computed as linear combinations of the same
state variables estimated and updated at the time when their last
sector servo was sampled, with different weighting coefficient for
each of the VCM control current update instants.  Therefore, the
currently disclosed algorithm estimates the state variables only...