Algorithm for Closed Loop Speed Control

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Algorithm for Closed Loop Speed Control

Postby limbq » Wed Dec 07, 2011 1:38 pm

Hi all,
Good afternoon~ :)

Pls refer to the attached illustration picture of my project.
Concept.JPG
Illustration of the concept

i am doing a project to control the speed of a pay off motor in a way that the speed of the pay off motor will just nice to transfer a roll of string thats attached to it to the take up motor. There is a tensioner pulley (with two channels rotary encoder as position encoder) between the pay off motor and the take up motor to control the tention of the string between the pay off motor and the take up motor and act as a feedback to the pay off motor to let the pay off motor know if it is turning too fast or too slow compared to the take up motor. If the pay off motor is turning too slow, the tensioner pulley will turn to position A, if the pay off motor is turning too fast, the tensioner pulley will turn to position B. Ideally, i want to controll the speed of the pay off motor to be synchronize with the take up motor and make the pulley stable at the centre point. The pulley can only swing +/-15degC the most and will be stop by a stopper.

I now having
a Planetary DC Geared Motor IG32E-100K as pulley tentioner motor with encoder,
a brushless motor BLH450K-A for the pay off motor,
IFC card of Main Brain, Control Panel, Power Card, Dual Brush Motor Card, and Brushless Motor Card.

My problem is,
i need a closed loop speed control algorithm that able to make the payoff motor synchronize to the take up motor,
The acceleration and deceleration of the motors are the critical part.
If the pay off motor is too sensitive, it may react too fast and oscillate to and forth and the pulley may not be stable.
If the pay off motor is very not sensitive, it may react too slow and the string may break.
And how to make sure the pulley will be stable at the centre at the steady stage? not to swing left and right due to the closed loop control instabiltiy ?
i have some reading and sound like we need the calculate the absolute speed error and the relative speed error from the previous stage and adding some constant gain to the formula? But the article didnt state clearly and i still blur.

Pls advise and thanks lot.
limbq
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Joined: Wed Dec 07, 2011 9:47 am

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