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Multirate Digital Control for Sector Servo System

IP.com Disclosure Number: IPCOM000036079D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Chiang, WW: AUTHOR

Abstract

Disclosed is a method to implement a digital controller for a disk drive actuator using a sector servo system. The controller estimates all state variables not only at sector servo sample time, but also at least once in between servo samples. The increased state estimation enables the computation of the voice coil motor (VCM) control current at a faster rate, and results in better control-loop performance.

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Multirate Digital Control for Sector Servo System

Disclosed is a method to implement a digital controller for a disk drive actuator using a sector servo system. The controller estimates all state variables not only at sector servo sample time, but also at least once in between servo samples. The increased state estimation enables the computation of the voice coil motor (VCM) control current at a faster rate, and results in better control-loop performance.

Optimum state estimator and state feedback control algorithms are implemented in the digital controller design. The state estimator is running at a rate which is an integer multiple of the sector servo sample rate. The estimator predicts in open-loop all state variables based on the dynamic model of the VCM/actuator system, and the predicted state variables are used for the VCM control current computation during times when the actuator position is not sampled. The predicted state variables are updated to the most likely values whenever the actuator position is measured at the sector servo sample time.

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