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Browse Prior Art Database

Sliding Mode Control for Arrivals And Small Movement

IP.com Disclosure Number: IPCOM000101935D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 5 page(s) / 126K

Publishing Venue

IBM

Related People

Anderson, TB: AUTHOR [+3]

Abstract

Described is a nonlinear control technique to improve the settle loop characteristics of a Direct Access Storage Device (DASD) servo system. DASDs are the high volume disk storage devices in Personal Computers. This method uses a servo controller known as a Sliding Mode Controller (SMC). Today's typical DASD controllers use a linear two-state feedback servo loop controller architecture. These designs can be tuned for a particular DASD but fall short of desired performance criteria in high-volume production applications. By using the SMC, adverse settle performance, due to variations in manufactured parts and initial state conditions, is minimized.

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Sliding Mode Control for Arrivals And Small Movement

       Described is a nonlinear control technique to improve the
settle loop characteristics of a Direct Access Storage Device (DASD)
servo system.  DASDs are the high volume disk storage devices in
Personal Computers.  This method uses a servo controller known as a
Sliding Mode Controller (SMC). Today's typical DASD controllers use a
linear two-state feedback servo loop controller architecture.  These
designs can be tuned for a particular DASD but fall short of desired
performance criteria in high-volume production applications.  By
using the SMC, adverse settle performance, due to variations in
manufactured parts and initial state conditions, is minimized.

      In order to understand this method, it is necessary to
understand phase planes and loop trajectories.  Figs. 1a through 1f
show six different trajectories of a second-order linear system.  The
vertical axis is velocity and the horizontal axis is position.  Each
trajectory represents the time response plotted on a phase plane for
different pole locations of the second-order system.  The pole
locations for each trajectory are:
      1.  Fig. 1a's poles are stable complex conjugate poles.
      2.  Fig. 1b's poles are unstable complex conjugate
          poles.
      3.  Fig. 1c's poles are stable poles on the real axis.
      4.  Fig. 1d's poles are unstable poles on the real
          axis.
      5.  Fig. 1e's poles are oscillatory poles, one
          negative, one
          positive on the imaginary axis.
      6.  Fig. 1f's poles are both on the real axis, one
          stable, one unstable.

      The conventional settle loop controllers use either Fig. 1a or
Fig. 1c pole locations.  The idea of Sliding Mode is to switch to
different phase plane trajectories in order to optimize the time
response and the target approach/arrival consistency.  Since the loop
pole locations (which determine the trajectories) are a function of
the settle loop state feedback gains, then the sett...