pic: 4143 differential swerve concept

[Chris is me]

Originally Posted by Nuttyman54

First thought: This is going to be impossible to make a module drive straight. A very small speed differential between the two wheels will make this turn for any reasonable driving speed gearing.

I think this depends on how low-friction the bearing setup for the steering is. Going with a more high-friction solution (i.e. a big hunk of close fit Delrin) could provide enough resistance to prevent slight differences in speed from spinning the module. Combine that with some closed loop velocity control between the two wheels, and I think it's a solvable problem. Not saying it isn't more trouble than it's worth, though.

[RyanShoff]

There would be not a differential, just two cantilevered wheels. All the comments so far are spot on. A higher friction pivot bearing would help. You would probably want 3 encoders, but maybe just one would work. The control loops are real interesting. I was thinking you could have one module with minicims to get around the cim motor limit.

One idea no one talked about is putting something like a caster angle into the modules. You could shift the wheels back slightly from the centerline of the pivot. The advantage being that they might track straight easier. The disadvantage being reversing direction would need a 180 degree twist.

This was mostly a modeling exercise, but with some development, it could be a viable drivetrain.

Step files coming soon.