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Position controlled seek operation with smooth current profile

IP.com Disclosure Number: IPCOM000014266D
Original Publication Date: 2001-Jun-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 3 page(s) / 101K

Publishing Venue

IBM

Abstract

Disclosed is the method to reduce undesired oscillation after seek operation of a hard disk drive. To reduce the undesired oscillation the method was proposed which uses an

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Position controlled seek operation with smooth current profile

   Disclosed is the method to reduce undesired oscillation after seek operation of a hard disk drive. To reduce the undesired oscillation the method was proposed which uses an

symmetrical acceleration and deceleration profile. (US Pat. 5291110) According to it if

the smooth deceleration profile which is required to reduce the undesired oscillation is

used, the acceleration profile must be smooth. That means slower acceleration and

therefore slower seek time. The proposed method uses smooth deceleration but uses

fast acceleration which means the derivative of driving current at beginning of seek is

larger than the derivative of the current at end of the seek. Actual seek control is

done by using the position profile that is generated by the proposed driving current.

The block diagram of a feedback system for the actuator control is shown in the fig.1.

The position target is used as a feedback target. Feedforward is used for faster

convergence to the target.

Position

target generator

VCM

Feedback controller

current

position

- +

+

Feedforward

+

+

+

Fig.1 Block diagram of an actuator control system.

For example the following position profile for the seek can be used to realize the

proposed method.

L

  
t
p

(

)

-=π248 


t

t

sin

7

7


M

M

π

0<t<M/2

1

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t
p

(

)

+-+=ππ412461 

...