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Unread 03-12-2010, 19:21
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FRC #1718 (The Fighting Pi)
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Re: Mecanum - use of gyro

Quote:
Originally Posted by Alan Anderson View Post
Before you do any more with the software, make absolutely sure your hardware is correct. A "stuttering" turn is sometimes a sign that you have your mecanum wheels mounted in the wrong orientation. The rollers contacting the floor should make an "O" or diamond pattern; they should look like an "X" from above.

Also make sure you understand what the inputs to the LabVIEW PID block mean. I haven't looked at it in over a year, but at that time the I and D parameters were not gains. They were time values. That scheme is just as easy to tune as a gain-based one, as long as you recognize that a smaller I or D value yields a stronger response than a larger value.
Oh. My. Gosh.

We've been using labview since FRC started using it, and I never even thought to check it: I just assumed it was a normal non-dimensional gain number that would act the way most PID setups expect it to act.

During this year's game we had a very robust targetting system in real time that would turn the robot and shoot after pushing the fire button. However, we removed it because we could not tune in the I and D portions to get the level of speed required: it was slightly slower than our driver's aiming and therefore wasn't effective.

I feel very, very silly right about now.
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