Browse Prior Art Database

Microprocessor Velocity Control of a DC Motor with Pulse Emitter Feedback

IP.com Disclosure Number: IPCOM000102322D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Decker Jr, WC: AUTHOR

Abstract

Disclosed is a method of calculating the pulse width of the motor drive current for a DC motor running in velocity-control mode using pulse feedback from an emitter or encoder and a microprocessor.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Microprocessor Velocity Control of a DC Motor with Pulse Emitter Feedback

       Disclosed is a method of calculating the pulse width of
the motor drive current for a DC motor running in velocity-control
mode using pulse feedback from an emitter or encoder and a
microprocessor.

      Microprocessor 1 uses timer 2 to generate a fixed frequency
varying duty cycle pulse train to drive driver 4 which, in turn,
drives DC motor 5.  As the motor rotates, emitter or encoder 6
generates feedback pulses, the period of which is measured by
microprocessor 1 using timer 3.

      Two asynchronous processes are used to control the motor
velocity.  Process A controls the Timer 2 such that the frequency
(the ON/OFF rate) is fixed, but the duty cycle (the length of the ON
portion of the cycle) is determined by a number received from process
B.  Process B determines the velocity of the motor by measuring the
period of the emitter pulses.  It then calculates the motor driver ON
time and passes it to process A.

      The ON time is the algebraic sum of two components: a BASE
value and an INSTANTANEOUS value.  The BASE value is based on the
average speed of the motor, but no mathematical averaging is
performed.  Instead, a rate-limiting technique is used to smooth out
jitter received from the emitter as follows:  If the velocity is
found to be too slow, a fixed amount is added to the BASE pulse width
to lengthen the ON time.  If the velocity if found to be too fast, a
fixed amount is subtracted from the BASE pulse width to shorten the
ON time.

      The second value used to influence the motor ON time is t...