Let's Make Robots!

Transistor based line follower

follows a black line on a white surface

Hi guys....



Finally today arrived the last order for this robot... the wheels and the caster....


I took me 2 night of CAD-ing...


This is  my first entry and I hope that you'll like this... I made this robot based on ermicro schematic and tutorial...  http://www.ermicro.com/blog/?p=1097


I used near the same things excepting the transistor... I'm using two 2N2222 transistor which allows 800mA on its collector... So the basic ideea is to follow a black line on a white surface... The principle of working is simple... I used a white LED to illuminate the surface... and one LDR as reciever/sensor.... when the white light contacts a white surface it will be reflected so the LDR lower his voltage opening the transistor... as the transistor is opening, the gearmotor gets more curent and will spin faster making it to turn...





unfortunatly I get tired with setting the trimpots every time when the illuminance changed... this way I was going to use QRD1114 fairchild sensor... and finally it's working... no more white light... :D just IR...


the only problem is that when my trimpots are at 0 Ohm, my LED isn't glowing :( the blue flashing LED :(

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If the comment was aimed at me, I don't get it. The line following switch will work.

the link is not working :P that was what i mean

Just Go to blogs and look for line following switch. Then Tell me what you think. Test it on your robot to see if it works, which it will :P

omg there are lot of pages :( btw :D I'll figure out some later :D now I use amega and attiny2313 :D

example A... yes this is like a simple 2 sensor based project but this like for example on the left if a sensor goes on black it slows the motor down... I transistor open, one close... current not flowing... if the curve is hard angled the second sensor will catch it again if the first interior sensor goes over... do you understand now the principle? on a simple black line both sensor are on white... transistor open...

I understand the principle now. :D shouldn't have doughted you. thanks for your time and help.

The only upgrade was to insert a line following toggle switch to follow dark and light lines.

go on :D I really want to see your design... there was a problem at dark light line :D didn't know how to make it :D

I will create a blog on how to create this line following switch. The nice part is that you can test the line follower with out having to engage the motor. :D I'll start working on the post then I will put a link as a comment on this page.

since you used ir sensors and recorded the video digitally you see the Ir light (purple color) Kool huh?

hey :D yeah its cool enough :D this robot took 3rd place at a competition :) for better turns and better line sensing I would advise you to use 4 sensors instead of too :D