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Browse Prior Art Database

Seek-Time Reduction by Initializing State Variables by Seek Length

IP.com Disclosure Number: IPCOM000118231D
Original Publication Date: 1996-Nov-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 4 page(s) / 60K

Publishing Venue

IBM

Related People

Nakagawa, Y: AUTHOR [+2]

Abstract

Disclosed is a method of seek-time reduction for a small storage hard disk drive which has a sector servo-controlled actuator. In a digital servo system, the servo controller generally has the history of previous output(s) as internal state variable(s). In this new method, firmware defines and sets initial value to the first output and the state variable(s) according to seek length in order to get faster moving of actuator speed toward the target.

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Seek-Time Reduction by Initializing State Variables by Seek Length

      Disclosed is a method of seek-time reduction for a small
storage hard disk drive which has a sector servo-controlled actuator.
In a digital servo system, the servo controller generally has the
history of previous output(s) as internal state variable(s).  In this
new method, firmware defines and sets initial value to the first
output and the state variable(s) according to seek length in order to
get faster moving of actuator speed toward the target.

      Fig. 1 shows a typical block diagram of digital servo system.
Fig. 2 shows an example of the controller in Fig. 1 and its
implementation by firmware.  Fig. 3 and Fig. 4 show outputs of the
controller described in Fig. 2 of one track length's seek with actual
hard disk drive, for example.  In this case, the first output and two
state variables are initialized with certain value defined by the
seek length so that the first and second outputs are large enough to
get fast acceleration toward the target, and the third output is also
large enough to get fast deceleration.  As the result, seek time is
pretty short, as shown in Fig. 5.

      In the implementation of initial value's selection by seek
length, not only conditional jump (if-then-else close) but also table
reference is used.  In addition, variables to be initialized are not
limited by output(s).  Input(s) also are available.