Crab drive steering

[Alex.q]

Last year, my team built a coaxial crab drive with all the wheels chained to gether for steering and separate gearboxes for left and right. We are in the midst of modifying and improving our design.

If we were to chain 2 modules together to steer, would it be best to link fronts and backs, rights and lefts, or opposing corners? What are the bnefits of different set ups?

Last year, our frame was 27 inches square, I think we did this thinking it was better for swerve drive, but is this necessary? We should be able set up the swerves in rectangle and account for different angles if necessary in programming, right?

Is it better to use an optical encoder or a potentiometer for sensing the direction of your modules? One problem/inconvenience we had is that the wheels would have to be pointed forwards when you turned on the robot otherwise the wrong direction was forward for the joysticks (we were using an encoder).

Finally, I ws wondering if there was an advantage to using belts to steer instead of chain becaue belts don't stretch. Would this be of any advantage?

Any advice would be welcomed.