LINE sensors

Which type of sensors are good to be used in white line follower robot on blue plane, IR with photo-transistors (OR) LED with LDR????

IR with phototransistors. An LDR will work but they are generally more expensive, have a slower response time, and don't filter out ambient light as well.

Pololu sells a nice Reflectance Sensor Array designed for line-following robots. Even if you're not interested in buying it you will probably find their documentation helpful.

I worked on IR with photo-transistor but they are not giving much variation, only variation of 0.05V which is very very less.. I have used this circuit Mechanical Engineering | College of Science and Engineering
This is the common circuit, everywhere this very circuit is used but its not giving much variation..
by the way i can't buy Pololu as i'm in Pakistan

Why anyone not replying?????? :frowning:

Please help me…
I’m using IR and photo-transistor and they are giving me variation of only 0.05V on blue and white surface…
my source is http://www.me.umn.edu/courses/me2011/arduino/technotes/irbeam/irbeam.html
any help, where might be the problem is??? Or IR gives not much variation???

I've seen these work well.
What's the theory behind how a part like this works? The kids calibrate them in software for the level returned for light vs dark and make successful line followers.
http://education.lego.com/en-gb/products/mindstorms/9844/

Are you using the exact same parts - or at minimum, similar parts with the same specifications as the parts shown? If not, then what parts are you using (and what are the specifications of them)?

Finally - once you get one pair working, look into setting up nine pairs in a grid (you can detect T and cross junctions that way - just a little hint).

:slight_smile:

Not using the same parts as shown there but i bought one from local radio shack and it has not written any specification on it but just said that it is IR and photo-transistor. :~

I couldn't find any IR and photo-transistor on which any specification is written so what should i do now?????