pic: Butterfly Drive

[GeeTwo]

If I were doing grasshopper/butterfly with omni wheels, I would definitely put the solid wheels on the hard, fixed axis which would be better at handling scrub forces, and cantilever/actuate the omnis, which (by design), do not exert much scrub force. I understand the desire to gear the solid wheels lower, but I'd rather make that work by actuating the motors and gearbox and providing some slack in all the wiring than to pull the scrub force through a cantilever.

Edit:

Originally Posted by Ty Tremblay

Wouldn't this be the best case scenario for this design since most of the force is transferred into the frame via the pneumatic cylinder? Or have I just been working too many night shifts?

Pneumatic cylinders should never be used to transmit significant forces except along the shaft axis. Solid wheels are going to be called upon for scrub (sideways, or into/out of the plane as you've sketched above) forces, especially in pin situations, and also in pushing matches. The pneumatic cylinder is not equipped to handle this force, and the parallel plates of a butterfly module are likely to "parallelogram" under this force. Exactly where this turns ugly requires more info than I have on your drive system, but at some point, you will have problems with the module hitting the side wall, a chain binding, or metal bending beyond its elastic limits.