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Detecting the Direction of Rotation of a Stepper Motor by Time Measurements

IP.com Disclosure Number: IPCOM000049016D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Goldrian, G: AUTHOR

Abstract

Generally, a change in a motors direction of rotation can be detected by means of a slotted disk and a sense station. For this purpose, the sense station requires two staggered sensors positioned at a particular spacing from the disk.

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Detecting the Direction of Rotation of a Stepper Motor by Time Measurements

Generally, a change in a motors direction of rotation can be detected by means of a slotted disk and a sense station. For this purpose, the sense station requires two staggered sensors positioned at a particular spacing from the disk.

A change in the direction of rotation can also be detected by means of only one sensor in conjunction with an evaluator circuit, utilizing the fact that at the point of reversal a far longer time is needed for a particular angle of rotation than during the preceding deceleration phase. A stepper motor which is to be very accurately controlled in spite of a very high step frequency needs a particular recovery time before it can be accelerated in the opposite direction.

By detecting the point of reversal, it is possible to accelerate the motor in the opposite direction without any recovery time. In the event of optimum deceleration of the stepper motor, the time between the step pulses is considerably shorter than the characteristic time the motor requires for a change in its direction of rotation.

In a given stepper motor system, the time indicating the point of reversal of the rotor can be detected. By continuous time monitoring (monostable multivibrator, counter, etc.), this point of reversal can be detected in the final phase of deceleration, and acceleration can be effected in the opposite direction. Such an effective change in the direction of rotation p...