A team I was a part of at the uni made a fuzzy logic-based robot for a soft computing course, almost 20 years ago it seems. I rember that we were able to accomplish seemingly complex behavior (light tracking with obstacle avoidance) with only a few very simple fuzzy logic rules. Seems the project page is still up, along with the source code, schematics and documentation (in Croatian): http://www.zemris.fer.hr/predmeti/nenr/