Past:
In 2002, the Technokats had a "Traction Control System" that we took a light sensor and pointed it at our treads. We still had metal treads and they reflected great. We also had a black and white wheel made of plastic and was painted. Another light sensor was used for the wheel, and we counted the differences in the tracks. A custom circut counted each and when the treads counted 16 (I think?) we sent a digital pin back to the OI. The system had three level of traction based on counts. It worked OK until the free wheel got pinched and we wore off half the wheel.
Today:
Now, you could make an encoder wheel to count your wheel speed for both wheels. You could use a rubber wheel to make a better roller wheel. You also have interrupts to make it super accurate! And you don't need a custom circut board!
