TomboT www.tombot.net

admin · Co Admin Joined: 22 Sep 2005 Posts: 34

In this forum we can discuss the many ways of creating an effective line following robot.

In terms of BEAM robotics, we can achieve this using the LM386 Herbie robot. I shall create a page with information for this purpose soon!

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Tom Elner, BEAM robotics@ Liverpool Uni
http://www.tombot.net

TomboT · Co Admin Joined: 16 Oct 2005 Posts: 11

I have created a line following tutorial now as promised.

I have not done it with the LM386 method because this type of line follower will not stop if the line disappears and is harder to control.

Instead I have made a line following tutorial based on 74AC240's.... this type of line follower will stop a motor if a line is not present, and so is capable of almost turning 90 degree corners.

Feel free to ask questions here.
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sismeya · Regular Joined: 12 Sep 2007 Posts: 2

Hi

I wonder if you could help a real novice, I am in the process of building the Line follower example you have very kindly posted, but you added in the instructions :-
" If your robot is following a black line on a white page, then add another invereter after or before the first" ...... I want to build a black line follower but dont quite under stand this could you explain in basic (very basic) terms for me ?

Cheers

Andy

TomboT · Co Admin Joined: 16 Oct 2005 Posts: 11

Hi Andy,

If you look at the first diagram on that page you will see next to where it says 'signal out' a triangle on its side with a circle on the end. This is the inverter, there are 8 inverters in total in the 74ac240. So all you want to do is instead of only inverting once, feed the signal through one more inverter.

In terms of the actual circuit then... what you need to do is look at the datasheet for the inverter and see the physical pin layout. Compare this to the circuit I have given and you will see that I have fed the 'signal out' line into more than one inverter. I have done this just to strengthen the signal, you don't need them all connected; in which case you can just disconnect a couple and route your signal back through.

HHmmmm not sure how clear I am being. I tell you what, have a look and see if you get me, if not let me know and I'll draw you up a new circuit, just let me know if you want it to be a basic follower or a full obstacle avoiding one like on http://www.tombot.net/beam/pics/c...blacklinefollowercircuitfull3.jpg
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sismeya · Regular Joined: 12 Sep 2007 Posts: 2

Hi

Thanks so much for the tips, I have tried to recreate the circuit you have suggested on a test board but I am obviously doing something wrong ..... I even managed to create a small puff of smoke .... if its not too much trouble could you please sketch out the diagram for the basic line folower but with the ability to follow a black line, I know its all about learning for yourself and discovering by your mistakes its just I only have two 74AC240 chips left !!

thanks so much

Andy