15-10-2008, 00:41
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[automate(a) for a in tasks_to_do]
 FRC #5507 (Robotic Eagles) Team Role: Mentor
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Join Date: Oct 2004
Rookie Year: 2005
Location: San Francisco, CA
Posts: 2,031
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Re: Motor Testing
Quote:
Originally Posted by EricVanWyk
At the risk of sounding like a hack, I am sure that the good FIRST students can figure out some good enough way to produce a given torque and a good enough way to compensate for supply sag. This isn't rocket surgery, and the first order linear model of a brushed DC motor is good enough for anything we do here.
Claiming that this is too difficult for a FIRST student is simply begging to be proven wrong. I'm betting it can be done entirely with KoP items and some creativity.
A brushed DC motor is a resistor, an inductor, and a voltage source proportional to speed, all in series. Current through the motor is proportional to torque. The voltage and current constants are equal to each other.
If you can measure current, voltage, speed and torque in several conditions AND do a small bit of math, you can find these constants.
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This sounds familiar...
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