Page 1 of 3 123 LastLast
Results 1 to 10 of 30

Thread: Line follower sensor dilemna

  1. #1

    Default Line follower sensor dilemna

    Hi y'all!! This is my first post
    Well i finally got down to building a line follower and worked on it for two weeks non stop. Made a pretty neat analog logic unit(using gates, k maps etal) and in the initial stages(breadboard) the sensor arrangement(LED+LDR) had given a good resolution between white and black but on the day we assembled everything onto the body whoosh no resolution!!
    Then we moved onto ir led+reciever arrangement and made it exactly according to data at[/img]http://www.roboticsindia.com/modules...s in advance!!

  2. #2
    Senior Member T-1000
    Join Date
    Mar 2005
    Location
    Bangalore
    Posts
    728
    Blog Entries
    7

    Default

    had given a good resolution between white and black but on the day we assembled everything onto the body whoosh no resolution!!
    1)
    Hmmm.... it has to be the ambient light!!! (if everything else is right
    )

    Cover up the LDRs!! so that only light which is perpendicular to the LDR disk reaches it. I would suggest you use the LED holders (if your LDRs are small enoughto get into them). Otherwise you will have to improvise something.

    2)
    Adjust the POT and see if there is any difference.


    had given a good resolution between white and black but on the day we assembled everything onto the body whoosh no resolution!!
    Check your batteries!! one way would be to see if the LEDs have gone dim!!

    good luck!
    .... I didnt do it ! ....

  3. #3

    Default

    even v thought it was ambient light until we switched off all the lights and even then v had the same reading on the multimeter, tested the ir rx tx sensor once again hell they are just not workin looks like god of sensors is just not happy with us!! shall try covering the ldrs!! thanks

  4. #4
    Administrator T-1000 rao's Avatar
    Join Date
    Feb 2004
    Location
    New Delhi
    Posts
    833
    Blog Entries
    2

    Default

    personally speaking , I am not a fan of LDRs, they are slow..

    The Photodiode and LED combination is great.. You say that your circuit was working on the breadboard and not when you made a PCB?? I would suggest you carefully go through your circuit on the PCB.

    Because I still end up making silly mistakes on my final circuits and find out a week later on some depressed night and go "duuhhh"... Check the grounds..

    Check if the angle is right between the photo diode and led because reflection is quite particular, at the right angle precision is just awesome.. parallel placing of the LED and Photodiode just lets a little share of the reflected beam to fall on the sensor..

    Not saying you are wrong, just saying you cant be perfect..

    Rao

  5. #5
    Super Moderator T-1000 docel's Avatar
    Join Date
    Sep 2005
    Location
    BANGALORE
    Posts
    1,441
    Blog Entries
    3

    Default

    ...people ALWAYS forget the School lessons: Angle of incidence = angle of reflection........
    In spite of explaining this, I always wonder, how students STILL make the mistake of placing the sensor emitters at an angle AWAY from each other :lol: :lol: :lol:
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  6. #6

    Default

    @docel: You need not always measure the reflected light, you can measure the diffused light which doesn't require the angles to be the same. Although for the line follower, it would be better to measure the reflected beam.
    --
    Kartik Mohta
    http://www.ee.iitb.ac.in/uma/~kartikmohta

  7. #7
    Senior Member T-1000
    Join Date
    Mar 2005
    Location
    Bangalore
    Posts
    728
    Blog Entries
    7

    Default

    you can measure the diffused light which doesn't require the angles to be the same
    Yes, we can measure, but the point was to follow lines!!
    .... I didnt do it ! ....

  8. #8
    Super Moderator T-1000 docel's Avatar
    Join Date
    Sep 2005
    Location
    BANGALORE
    Posts
    1,441
    Blog Entries
    3

    Default

    Well! ??

    ...and you know...

    NONE of the IR sensors worked at Techtathva07, NITK --
    except the Hosts' own LDR circuits.... 8O
    The WHOLE stupid black Line (and the White) was glowing like the Summer Sun....

    And why should diffused light have NO angle of reflection. ???
    This is more tricky with the IR, what with the surfaces having unknown IR reflective/Transmissive/absorbent properties. :!:
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

  9. #9

    Default

    The diffuse light would not have any angle of reflection because it is the "diffused" beam not the reflected beam. see: http://www.ogre3d.org/wiki/index.php/Diffuse_(Light). Of course, it would be a very small proportion of the total light, but enough to detect whether there is something there.
    And I guess that the diffusion by black would almost be negligible even though it might reflect some amount of light, which might allow you to better judge whether the line is there or not.

  10. #10
    Super Moderator T-1000 docel's Avatar
    Join Date
    Sep 2005
    Location
    BANGALORE
    Posts
    1,441
    Blog Entries
    3

    Default Confused!!

    kartikmohta !!

    After saying this :arrow:

    Quote Originally Posted by kartikmohta
    @docel: You need not always measure the reflected light, you can measure the diffused light which doesn't require the angles to be the same. Although for the line follower, it would be better to measure the reflected beam.
    --
    Kartik Mohta
    http://www.ee.iitb.ac.in/uma/~
    What are you trying to say...... now :?: :?:

    Quote Originally Posted by kartikmohta
    The diffuse light would not have any angle of reflection because it is the "diffused" beam not the reflected beam. see: http://www.ogre3d.org/wiki/index.php/Diffuse_(Light). Of course, it would be a very small proportion of the total light, but enough to detect whether there is something there.
    And I guess that the diffusion by black would almost be negligible even though it might reflect some amount of light, which might allow you to better judge whether the line is there or not.
    This makes very little sense to me :?
    docel
    ^Anything is possible..
    after YOU prove it!!

    http://bangalorerobotics.tripod.com

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •