Hey, all. I’m open sourcing my small competitive robot from last year, YellowBot_02, as well as a general-purpose chassis I designed based on it. All are shared as OnShape links (a web-based CAD that works like SolidWorks); you can export STLs from there or fork it and design further. The chassis is covered in a grid of 3mm holes at a 6mm distance; this makes it easy to design accessories in whatever CAD you like and attach with #6 or M3 screws and nuts (or even just zipties).
Last year’s MiniFRC robot, YellowBot_02, was discussed on this blog here. The CAD for it is available here. This CAD includes a mount for the Alfredo NoU and a battery (9V or 6xAA pack), as well a servo mechanism specific to that year’s game. Works with standard yellow gearmotors — they ziptie into the chassis.
Here’s a general purpose chassis I developed from that: ScienceBot. Same hole pattern, but in more places, and no big name on the back. I’m using this design for my undergraduate research students, too. Includes vertical mounts for an Arduino Uno plus Raspberry Pi (the latter not relevant to MiniFRC), a 3×18650 battery pack and 5V regulator (neither relevant to MiniFRC), and three MaxBotics ultrasonic sensors (probably not relevant to MiniFRC). Compatible with all the same mounts and motors as the YellowBot_02 chassis above.
If you want to DIY your wheels, here is a design for two-part wheels with the same dimensions as the stock yellow-and-black ones. There’s an inner hub designed to be printed in regular rigid PLA, and the wheel itself, which is meant to be printed in squishy TPU filament (also known as Ninjaflex).
You can get even better traction if you spray the outside of the wheel with PlastiDip.
Here’s a video tour of the old YellowBot that I did as part of a fabrication tutorial at Duke:
Here’s a video of the new ScienceBot chassis with the TPU wheels doing a motor test: