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# Hard Disk Drive Actuator Feed Forward Control Method

IP.com Disclosure Number: IPCOM000101234D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 63K

IBM

Ono, H: AUTHOR

## Abstract

Disclosed is a Hard Disk Drive (HDD) Actuator Digital Feed Forward Controller Which is Implemented As a Finite Impulse Response (FIR) Filter in Addition to a Conventional Feedback Controller.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 58% of the total text.

Hard Disk Drive Actuator Feed Forward Control Method

Disclosed is a Hard Disk Drive (HDD) Actuator Digital
Feed Forward Controller Which is Implemented As a Finite Impulse
Response (FIR) Filter in Addition to a Conventional Feedback
Controller.

The objective of this method is to obtain faster seek motion
nder enough stability.  Feed forward components are designed to
follow a desired actuator trajectory concerning the closed feed back
system characteristics.  Robustness to the settling/track following
stability depends on the feedback controller design which is based on
a conventional approach.  FIR filter utilization has no limit cycle
problem in digital calculation.

The figure is a block diagram showing the controller. The FIR
filter is placed between a step target input and a conventional
closed-loop controller input.

Feedback gains F1 and F2 are designed concerning system
robustness by conventional design method on the modern control
theory.  Then, the FIR filter coefficients are obtained by following
the procedure described below.

1.   The closed loop system is stabilized by the feedback gains
F1 and F2.  Then, the system is expressed by Equation 1 and 2.
x(i+1) = G x (i) + D r(i) - - Eq 1.           (1)
y(i)   = C x (i)          - - Eq 2.           (2)
where x(i) is a state vector of i
r(i) is a target input of the closed loop system
...