Funny you should mention it— I built a line-following system into the forklift, using an Arduino: I put a row of 16 downward pointing leds on the bottom of the chassis; the Arduino sequentially scanned all 16 leds. A photocell detected reflected light from the floor, and fed this into the Arduino’s analog input. In turn, this let the Arduino decide which side of the line it was on, and how much to turn to get back on track.

But odometry proved a bit more challenging, and it turned out to be more reliable (and fun) to simply move it using a RC controller.