Thread: Is there a speed sensor input example for Labview?
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Unread 24-02-2013, 21:15
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Um, I smell Motor!
AKA: Scott McBride
FRC #2137 (TORC)
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Re: Is there a speed sensor input example for Labview?
We are using a banner sensor, (very similar to AB, just smaller packaging, and polarized) two pieces of reflector tape, on a vex hub. We have sized the tape so it is 90 degrees on, 90 degrees off.

We are using the same code that was posted, and but averaging over two samples to balance any, not quite 90 cuts, on the reflectors.

This is giving solid RPM measurement. We are controlling with "take back half" controller, posted by 123 last year.

Our target speed is 3700, and max speed of 4400 on the wheel. We have confirmed the speed with a handheld optical tachometer. We come to speed in about 2.8 seconds, and can hold a +- 3% to shoot.

We tried bang bang, but the counter resolution was fighting with the motor update cycle. I realize now the problem was the RPM calculation, with the low resolution "encoder" we could really only calculate RPM's in steps of 300 RPM's. TBH is working, so we are working on things that aren't but when I get time we will go back and try bang-bang with rpm calculated as period in lieu of counter, to see the real comparison.
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Last edited by tr6scott : 24-02-2013 at 21:22.
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