4 Wheel Drive Too Much Traction

[JesseK]

There are several things wrong with this drive train setup, and there are multiple ways to remedy it. The root cause is pointed to by David, and the result is that your entire robot is current limited while turning (pulls more than 120A while turning @ 12V...which causes battery voltage to drop*). I can confirm Mr. Gregory's gear ratios because last year that's exactly what we ran (12:32) using higher traction 6" wheels and no issue with turning (though our wheelbase was MUCH wider than it was long...).

Start by examining the attached photo that was created with this tool (not to toot my own horn -- but there are a couple of tools on CD that should come on a KOP CD or something ... namely, JVN's to start with).

In no particular order, you could do one or more of the following:

1. Use omni wheels
2. Use smaller wheels
3. Offset your center of gravity
4. Swap Gearboxes to Toughbox Mini's/Nano's (hard to tell exactly what gearbox you have -- looks like CIMple boxes since the CIM shafts stick out)
5. Make a 'lessons learned' so your team never designs a wheel base that is longer than it is wide
6. Use 12:32 or 14:38 sprocket reduction, in picture 2
7. Change the cogs on the gearbox to 16-tooth cogs with the same tooth profile

*One day I'll get around to updating my sheet to model this, now that I understand it better