[Tom Line]

Drive bases with omniwheels at each corner like that can be very hard to control at times. They tend to be difficult to drive straight.

What is the final speed of the drivetrain? That's a pretty large gear on the transmission output shaft.

We've had very little luck tensioning chains using the manner you've shown. The friction from the single fastener in the end of the cam shafts simply isn't enough to keep the cam stationary and they will end up spinning. Drivetrains generate a surprising amount of force on the chains.

It appears that the only thing holding the chassis 'square' are the 2 bolts at each junction between the side modules and the front crossbar. This will not be strong enough, and you will want gusseting. You will probably also want support across the middle of your chassis - that's why so many teams use a solid belly pan. It stiffens up the platform significantly.