pic: top view

[Tristan Lall]

Originally Posted by Chris is me

It's the end of week 4 but PLEASE consider doing a large redesign of your drivetrian.

Do what Chris said, immediately.

I just ran some calculations, and you're going to be drawing more than 40 A on each drive motor for about 3 s every time you accelerate from rest (and averaging roughly 75 A per motor during that period). Although there's some margin involved with the Snap-Action circuit breakers (i.e. momentary surges won't trip them right at 40 A), this sort of usage pattern is almost guaranteed to fail. Not to mention that this puts you at significant risk of throwing the Bussmann 120 A main breaker as well. (Datasheets: Snap-Action MX5, Bussmann 185120F.)

Furthermore, even if you accelerated diagonally from rest across an empty (i.e. no field elements) field, you'd only hit about 30 ft/s by the time you came to the opposite corner, even though the robot is geared for almost 39 ft/s. That's pretty much the definition of pointlessly fast.

If you can cut your speed in half, you ought to be on the limit of controllability and circuit breaker reliability. While you could do that simply by cutting your motor voltage in half (i.e. using the speed controllers to give them 6 V), you're still going to have dreadful acceleration and handling. The only way to actually have a chance to hit top speed on a regulation field involves changing the gear ratios.

It looks like your ground clearance is too small to allow you to switch to 4 in (non-mecanum) wheels without some reconfiguration. (That would have been another way to get a usable gear ratio out of the robot with relatively little modification.)

Bottom line: plan to either switch to some variety of AndyMark Toughboxes (the kit gearboxes from last year, or the Mini or Nano versions with similar gearing in a smaller package), or design and install a chain-drive reduction.

By the way, leaving the wheels cantilevered off of the gearboxes like that is not necessarily a good idea. Although the shafts and the gearbox casings ought to be able to withstand the bending load, the mounting flanges and screws for the gearboxes probably won't. They could easily become detached from your base plate, or at least misaligned. Your best bet is to support the wheels with a bearing on either side (but no more than two bearings on any shaft, unless you've carefully designed for that case).