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Unread 28-12-2016, 16:27
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Jared Russell Jared Russell is offline
Taking a year (mostly) off
FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
Team Role: Engineer
 
Join Date: Nov 2002
Rookie Year: 2001
Location: San Francisco, CA
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Re: Drivetrain PID tuning

Quote:
Originally Posted by sspoldi View Post
In 2015 we used Mecanum wheels and one thing we really noticed was that the robot would rotate and drive forward well, but generated a lot more random slipping when moving sideways. We ended up using encoders for forward and lateral positioning and the gyro for heading. We could have used the encoders (one on each wheel) to determine heading, but the slip was giving us problems.

It was worse when the wheels got worn out. we were using the 6" Vexpro wheels, very cost effective but had a very noticeable life span for the rollers. Replacement wheels altered our autonomous timing required for the 3 tote auto.

Cheers,
Steve.
This is very common for mecanum drives. The rollers don't need to spin for forward movement or turns in place (depending on your drivebase geometry), but do need to spin for sideways translation. The less your rollers spin freely, the more your strafing performance suffers.
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