Issues with Drivebase

[GeeTwo]

Opening with some quotes from another thread...

Originally Posted by NathanCJohnson

But we're using 6" traction wheels in the front and 6" omniwheels in the back (the middle wheels are the 4" wheels that came with the KOP drivetrain).

Originally Posted by Ether

You said the middle wheels are 4" and the front/back are 6". Have you geared them in the proper 6:4 ratio so they are going the same tangential speed?

Originally Posted by GeeTwo

The center axle on the AM14U2 is only dropped 1/8". Since the corner wheels are 2" larger diameter, the 4" center wheels float 7/8" off the carpet. In effect, the 4" wheels are just a spacer for the belt sheaves.

Originally Posted by Ether

Except when going over the platform.

Originally Posted by GeeTwo

Yes, that would be a literal speed bump.

There was a robot at Bayou with a KOP chassis, 6" omnis on the corners, and 4" KOP wheels in the direct drive positions. I asked the driver how it handled, and he said that the 4" wheel actually helped getting onto and over the platforms, though he wasn't very articulate as to how or why. I'm guessing that the lower gear ratio and higher CoF turned the robot so that it was attacking the slope more directly, and gave a bit of a boost on the lift. The undersized middle wheel would produce less rocking as the weight shifted to a different pair of axles, reducing the likelihood of spilling a stack.