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Control Design - PID and Topic Publishing

asked 2012-10-17 06:09:09 -0600

101010 gravatar image

updated 2014-04-20 14:09:23 -0600

ngrennan gravatar image

I am using 2 phidgets high current motor controllers to operate 4-12VDC motors, using the joy package to interpret my saitek av8ter joystick, with axis scaling for velocity control. With the rxgraph depicting the joy node publishing to a teleop node publishing to a move node, thus commanding the phidget HC controller to move the desired motors with the desired velocity. The callback for the teleop node, that publishes to the move node, listens to the joy topic, interprets the axis change, scales and publishes to the move topic. What I am seeing is a humming of the 12VDC motors during the initial motion of the joystick in the desired direction until a proper velocity to rotate the motor in a sufficient manner.

Has anyone experienced this type of behavior with their VDC motors? Should I not be continuously publishing or subscribing to the topic responsible for velocity changes? Is this even considered a problem?

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You should only need to publish when you see a change from the joystick. Probably it's sending some command that is just enough to energise the motors (and thus make them hum) but not enough to overcome the initial inertia

MarkyMark2012 gravatar image MarkyMark2012  ( 2012-10-18 01:26:48 -0600 )edit

Exactly. Thank you for the confirmation. An additional question is if the continual hum would cause any degradation of the motors in the long term.

101010 gravatar image 101010  ( 2012-10-18 03:48:16 -0600 )edit

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answered 2012-10-18 21:30:27 -0600

MarkyMark2012 gravatar image

You'll be wasting power for one thing. As for damage to the motors, no not realy. After all it's not like they're at stall current.

But I would suggest that you figure out how to keep them off when not in used.

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Asked: 2012-10-17 06:09:09 -0600

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Last updated: Oct 18 '12