Line Follower robot (LDR)

[Voltboy]

Hello guys.
I know that most line following robots use photodiodes or phototransistor or IR recievers.
I wanted to know if using LDR it could work.
The schematic attached is the circuit I'm thinking to use for each receiver.
And maybe instead of connecting directly to the motor I could connect to a comparator first.
What you say about it?

 

[philba]

I think more line follower sensors use IR - visible light can interfere with your LDR. The IR sensors typically have a visible light filter.

I've used phototransistors to good effect. Cheap and very easy to interface to a microcontroller.

How exactly is your line follower going to work if the sensors drive the motors? seems a lot harder than using a microcontroller.

 

[Voltboy]

Well the circuit withe the LDR works very simple. The motor speed is proportional to the light over the LDR. So if lets say the line is reflecting light to the LDR one side will go fast and the other motor (assuming its a curve) will be off because of darkness.

 

[philba]

in theory. if it works the way you expect, what's to prevent over shoot? I suspect that if it works at all, you will get oscillation.

What happens when neither sensor is over the line? Lets also not forget external light interference.

A good line follower uses more than 2 sensors.

 

[Voltboy]

Yes I know that, it was only supposing, i got about 10 LDR's