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Unread 08-01-2017, 23:44
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GeeTwo GeeTwo is offline
Technical Director
AKA: Gus Michel II
FRC #3946 (Tiger Robotics)
Team Role: Mentor
 
Join Date: Jan 2014
Rookie Year: 2013
Location: Slidell, LA
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Re: 2017 Drive Train

In 3946's experience, H-drive is harder than mecanum.

In 2013 Aerial Assault we decided to do mecanum (foolishly expecting a less defensive game), and it worked as well as expected, pretty much the first time around (OK, after fixing some wheel order issues), but we had it running two weeks after we made the decision on our prototype "Woody" (which meant ordering wheels and extra gearboxes before we could finish the build) and running like a champ on the competition robot "Buzz" before bag day. We used the WPI mecanumDrive class straight up, without encoders.

In 2015 Recycle Rush, we decided to do H-drive, and never got it working correctly all the way through CMP. It was only after the 2016 season that we got it working. If you do do H-drive, do not depend on a fixed-height strafe wheel - there is no height which provides the correct amount of load. The central wheel(s) must somehow have a controlled force against the carpet, whether passively through springs or actively through pneumatics or torque actuation, or perhaps some other ways you can come up with.

Another caveat which may or may not apply to you: H-drive requires a wheel near the CoG of your chassis (or one forward and one behind). This will interfere with the "chassis opening and combine" style gatherer that is likely to be commonly used by fuelbots this year.
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