[Nathan Streeter]

Looks much improved! It looks like the pod would be plenty robust (perhaps a little beefier-than-needed even), but I usually prefer to air on the side of over-engineered in the first iteration of a design.

Regarding the pod actuation, I would recommend - if possible - actuating it in such a way that you get a mechanical advantage rather than a disadvantage. In this case (with the moment arm from piston-to-rotation being shorter than the moment arm of actuating-wheel-to-rotation), you'll need the piston to push with more force than 25-50% of the robot's weight. Mounting the piston somewhat-vertically over the last standoff on the module would achieve a mechanical advantage, but frame integration is really only worse with that...

Does anyone on here have experience with cantilevered butterfly/octocanum? We've never tried cantilevering the axles on our butterfly (although we did consider it for maintenance reasons), but it might be reasonable... If you do it, I'd definitely recommend working hard to minimize the distance from your wheels to the main frame piece, and to make your frame as wide a box as is reasonable. The loading for a cantilevered octocanum/butterfly is a lot more intense than the typical WCD; you have the typical driving torque and weighted bending, but also the forces applied by the actuated wheel the piston when in traction mode are going to be powerful torques. Our shafts were simply-supported 1/2" tube shafts... I liked them alot, but we built it around a fully-enclosed sheet metal 'tube' that also housed the actuation pistons. They didn't need to transmit torque because we had the CIMs mesh directly to a gear on the first wheel.