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Stepping Motor Stop Control

IP.com Disclosure Number: IPCOM000087323D
Original Publication Date: 1977-Jan-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Barnett, JA: AUTHOR [+2]

Abstract

In certain applications, a load driven by a stepping motor tends to overshoot its target position. This tendency can be decreased by reducing the motor winding current during the latter part of the deceleration, as the motor approaches its stop position. In addition, this control is enhanced by the ability to compensate for load variations by use of feedback-referenced stopping pulses.

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Stepping Motor Stop Control

In certain applications, a load driven by a stepping motor tends to overshoot its target position. This tendency can be decreased by reducing the motor winding current during the latter part of the deceleration, as the motor approaches its stop position. In addition, this control is enhanced by the ability to compensate for load variations by use of feedback-referenced stopping pulses.

Referring to Fig. 1, a pedestal control 1 opens or closes switch 2 in parallel with current limiting resistor 3 in the supply circuit for motor windings A, A, B and
B. The windings are individually controlled by respective switches 4-7 operated by winding sequence control 8. Fig. 2 shows an example of an eight-step movement for a motor. The first motor advance pulse results from the occurrence of a motor run signal and, coincidentally, the pedestal switch 2 of Fig. 1 is turned on to bypass resistor 3, thus increasing the current available to the motor windings. Succeeding motor advance pulses are generated in a closed loop system by the feedback signal received, for example, from an optical or a magnetic disk.

At the termination of the motor run signal, a stop command is initiated at the occurrence of the first leading edge of the next feedback signal so that a Stop 1 interval is begun. At the completion of this time interval, a motor advance pulse is generated. At the leading edge of the third feedback signal during deceleration, the Stop 2 time interva...