[EricH]

There are quite a few ways to do a swerve drive. There's fully independent steering (each module has its own turning motor). There's all turning at once. (This one really needs some other way to turn--or a turret, noting 118's 2007 robot.) There's front/back and left/right module linkages.

I don't think your turning solution is optimal--it'll work for turning in place, but it could be really nasty for anything else, programming-wise, especially if you get a wheel off from the rest by mistake. And the chain runs are going to be especially interesting--you're forming an X with the chains, and hopefully you find a good way to do that without risking fouling up. I've seen that done before, with 4 runs, and it worked OK, but I think it was the propulsion power runs from the center to the edge and the rotation runs on the outside.

What I might do, as an experiment (and I don't know if anybody's fully run this on coaxial), is to turn all the pods together, but have left/right or front/back motor units. Think of it like tank drive where the wheels can pivot for sliding sideways. It's somewhat easier to do with the Wild Swerve module (also available from AM/221 Robotics Systems), but could be really interesting to try a coaxial version.

Incidentally, I've never been on a team that used swerve drive. The closest was 2009, two years after I left, and if there hadn't been a trailer towing behind the robot it would have been a turreted robot instead of a pivoting drivetrain.