Pretty cool video explaining how some omniwheels work, and then he makes one to test.
Omniwheels are cool. Shatter from BattleBots uses them to flank opponents while keeping their hammer on target. https://youtu.be/ZPOd-DxTbcc
They're more complicated and fragile than conventional wheels (so you need to spend some weight on wheel armor), and they get less traction, but they're really neat and I wish more bots used them.
Well I just spent the last couple hours at work watching battle bot clips and reading about the bots on their wiki.
It's in season right now! Discovery channel every Thursday night, with a bonus fight uploaded Sundays. If you don't do tv people are also really good at uploading the fights on youtube, but then you miss all the fluff in between.