It has been a few years since we initially posted this Basic Line Following Robot with Arduino tutorial, and it appears so many people found it helpful that we should post an update which runs current Arduino Libraries, includes the newer robot kits that assemble faster/easier, and further explain some of these steps for those who may be very new to robots and Arduino.
In this tutorial, the goal and approach is the same as before. We are building and programming a robot that can follow a lined course with the use of an Arduino based micro controller system programmed to run a basic Proportional speed control. Proportional is a simpler and shortened version of a PID control. You can visit these Wikis to learn more about both systems :