A small bot and suspension. Big task. But after taking some HDD appart and looking at round things for some time I came to suspension anyway. For a small bot this will work, i'll try and make it functional in the Rommel robot. You need per wheel 2 rings of let's say 1cm wide, a bigger and a smaller one (pick your size on availability). The inner ring will be connected to motor or axis. Arround that the second (bigger) ring goes, and the idea: in between you put some rubber or foam like material (depending on the weight of the bot). So basically you have 3 rings of which one is "soft" and will respond to impact. It's worth a try.
Crap, I wish I was born in
Crap, I wish I was born in 1912. Everything I can think off is already there. And better.