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Unread 29-01-2013, 20:56
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AKA: Tucker Campbell
FRC #3753 (Bulah Bots)
Team Role: Alumni
 
Join Date: Jan 2012
Rookie Year: 2012
Location: Baton Rouge, Louisiana
Posts: 190
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Re: 3753 shooter. 12 points in 2 seconds

Quote:
Originally Posted by Andrew Lawrence View Post
Your shooter looks amazing! Would you mind explaining it in further detail? How can you shoot so rapidly? What kind of motor/gearbox setups are you using? How much squeeze do you put on the frisbee? How much room is in between your wheels?

This looks like an awesome design. I can't wait to see 3753 in action this year. Keep up the good work!
[Warning: I'm a programmer, not a mechanic. Sophisticated vocabulary inbound]
We actually didn't do anything complicated, it just all worked REALLY well!

Our shooter is pretty simple: Two CIM motors with Pneumatic wheels attached, and a Window Motor with a small piece of L bracket stuff attached to the plastic black wheel thing. The window motor and its attached arm push frisbees into the two wheels, which then shoot the frisbees. We put stoppers (screw) in the way of the window motor's arm so it could only turn so much either way.
If you look at the first video in my signature, you'll see some pictures of the shooter before we put our feeder on top.

As for shooting fast, I programmed the window motor like this:
Code:
When button 3 is pressed
1) Set the window motor's output to -1 (forward.  We mounted the window motor upside down, so the (-) is forward and vice versa)
2) Wait x miliseconds
3) Set the window motor's output to 1
4) Wait x miliseconds
5) Set the window motor's output to 0, ending orders to the arm (so that it doesnt CONSTANTLY try to push against our stoppers and mess up the motor)
I'll attach a picture of this for anyone who's curious how to code it. As someone who's new to labview this year, it took me a while to figure out

The way the code is set up, hitting the button ONCE will make the action run once -- it doesn't matter if you let go of the button before the sequence ends, it will finish the whole order. If you hold the button down for longer than the duration of one sequence, it'll loop repeatedly. Since our stoppers are FAIRLY close together, the arm only turns about 70 degrees, meaning it doesn't take long to go from one stopper to the other, so it can go forward and back in a fraction of a second. Looping it gave us the results you saw

Hope this helps! Now we just need to decide on a climber (and a climbing destination)
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