the obstacle detection block doesnt have to do anything with the rpm of the motor.
The link I gave, you need to learn only the IR obstacle detection part.
For the main drive using dc motors, search and study "H-Bridge". Use an IC like L298D.

__________________
Its not the Practice that makes a man perfect. Its the Man who makes the practice perfect
----- Pradeep K. Shima -----

 

Sir,I want to construct a line follower.
So please tell me the components require for it along with their ratings.
Also provide me with detailed procedure & neccesory circuit diagrams.

 

Why dont you google for it Gaurav ?

The internet is flooded with detailed designs, pictures etc. of line followers.

__________________
Its not the Practice that makes a man perfect. Its the Man who makes the practice perfect
----- Pradeep K. Shima -----