Here's a robot that I built last year to follow the lanes of a small test track. This was built 24 hours before attending Chris Anderson's DIY Robo Cars meetup. I was told about it and thought it would be fun to show up and participate. Unfortunately the rules are a bit bizarre, as it's not about staying in the lines but making it "around the track", which is a very loose rule. Pretty much, you can win this meetup competition if your robocar can drive a circle the fastest, whether in the lines or not.
My intention was to stay in the lines, because that made sense to me. But hey, I might be crazy assuming robocars are meant to actually stay in a lane on a road *shrug*
The day before the meetup, I didn't have any material to make a real test road, so I placed white pieces of paper on the floor. Had to keep the windows closed because they weren't taped down, and the wind moved them - haha. The test robot I used was simply a modified AdventureBot. Using EZ-Builder, I created multi-color profiles for the lanes and off my robocar went...
I attended the meetup the following morning. Like i mentioned earlier, a little disapointed in the lack of real-world vehicle rules... but it was still fun! My little robocar, that took less than an hour to build an program with EZ-Builder was the only robot to make it around the track continuously... that is, until someone elses road-raged robot drove into mine
The next day, I was still a little caught up on perfecting the EZ-Builder features for this exercise. I wanted the robot to move a little quicker, which was limited by the WiFi camera frame rate, however. I did end up making a better track in my house, and like a model train, I let my new robocar drive the mini-road until the batteries died!