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Unread 20-03-2011, 13:38
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AKA: Andrew Nicholson
FRC #1778 (Chill Out)
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Join Date: Jan 2007
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Re: Robots not under driver control- does it happen- do you determine why?

Quote:
Originally Posted by willishf View Post
In theory the gearing ratio could be 2.166667 from the wheel to the rotation of the optical encoder shaft and the reason for the non integer multiplier. Always feel better when you have nice integer multipliers.
The output shaft of the gearbox has a 12 tooth sprocket, the wheels have 26 tooth sprockets: 360 (encoder counts) * (26/12) = 780

Note: An encoder labeled "360" will give 360 counts at 1X as it counts only the leading edge of A, 720 using 2X, counting leading edges of A&B (or leading and trailing edges of A), and 1440 using 4X which counts leading and trailing edges of both A&B signals.

PS. The cRIO FPGA handles the signals from the encoders and does not cause interrupt overload. Some teams have the encoders wired into CAN controlled jaguars - these do not cause interrupts either.
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Andrew Nicholson
2011 FRC Robot Inspector (Seattle, Portland)
Mentor FRC 1778 "Chill Out", FTC 3018, 3940 "Hawks", 4434 "Heat Misers"

"Everything should be made as simple as possible, but no simpler."

Last edited by AndrewN : 20-03-2011 at 13:40.