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Method for High Speed Position Feedback from Stepper Motors

IP.com Disclosure Number: IPCOM000106159D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2005-Mar-20
Document File: 2 page(s) / 72K

Publishing Venue

IBM

Related People

Singletary, A: AUTHOR

Abstract

In many industrial movement systems, rapid and accurate position feedback is essential. This has traditionally been accomplished through the use of encoders or resolvers. In the case of multi-axis linear stepper motors these approaches are not viable because of the mechanical configuration.

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This is the abbreviated version, containing approximately 78% of the total text.

Method for High Speed Position Feedback from Stepper Motors

      In many industrial movement systems, rapid and accurate
position feedback is essential.  This has traditionally been
accomplished through the use of encoders or resolvers.  In the case
of multi-axis linear stepper motors these approaches are not viable
because of the mechanical configuration.

      Disclosed is an approach to obtaining position feedback based
on the control signals going out to the stepper motor system.  It
depends on the assumption that the mechanical system always acts in
accordance to the control signals.

      The approach is based on monitoring the step and direction
control signals and feeding them back to high-speed counters which
maintain position information.  Details of the implementation are
shown in the figure.  The movement system controller is an industrial
computer based on the IBM PC-AT architecture.  High-level motion
commands are inter- preted by a stepper motor controller card which
sends out logic level step and direction signals to a stepper motor
driver.  The driver then converts the signals to motor currents and
directly controls the stepper motor itself.  The positioning approach
disclosed is based on intercept- ing the logic level signals between
the controller card and the driver.  As shown in Figure 1, the
signals are buffered on an interface card before being sent to the
motor driver.  Also on the interface card, these same step and
directio...