Here the another Line Follower robot tutorial… The robot mechanical design not included, you may create the shape and the mechanical design of your line follower robot by your self. Just use motor gearbos which have high torque… 
This line follower robot use the following module:
Original post, visit this site: elm-chan.org
Before read the rest article/tutorial, please watch the video first.. . See the robot’s movement and i’t speed. This is very great…!
You may see the video here.
This line follower robot is very small and simple. This robot is running fast and follow the line very smoothly.
Mechanics
This can be used as reference