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Unread 17-03-2010, 13:54
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Re: encoder for cam-driven kicker?

Quote:
Originally Posted by Chris Hibner View Post
If you want to use a relative encoder, your cam actually makes that quite easy. Start each match by driving the kicker motor backward with a small enough PWM so you don't damage anything. Montior the rate of the encoder. Once the encoder stops moving, you know you hit the edge of your cam. Reset the encoder position and then start using the kicker as you normally would. By doing this, you will get a very accurate zero point of the encoder every match.
Great suggestion, but may not be robust for our configuration. We'd have to thread the needle between going slow enough not to damage the motor/cam, and going fast enough not to get a penalty for having the end of the kicker outside the frame perimeter for more than two seconds. Also, it would chew up valuable time in autonomous.

What I envisioned doing instead was to pre-configure the cam in the "armed" ready-to-kick position when the robot is placed on the field. Then at the start of autonomous, zero the encoder counter.

What is the data type of the encoder counter in the FPGA? Is it large enough to just let it run free without overflowing during a match ?


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