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TSL1401-DB Linear scanner — Parallax Forums

TSL1401-DB Linear scanner

memooo2006memooo2006 Posts: 8
edited 2010-10-26 23:23 in Robotics
Hi everybody:smilewinkgrin:
I just have a quick question about the TSL1401-DB. Can I use it to get a horizontal position of an object that is 30 cm away from the sensor?

I am building an electromagnetic levitation project that has an adjustable vertical and horizontal position of an object.

I was thinking of using the TSL1401-DB sensor for sensing the horizontal position.

so please guys let me know what do you think about that..
also other ideas of sensing the horizontal position is welcomed:hop:.

appreciate your help

Comments

  • dandreaedandreae Posts: 1,375
    edited 2010-10-26 07:32
    The overall width (field of view) seen by the TSL1401-DB, using the included 7.9mm lens, is approximately equal to the subject distance. So, for example, if the module is 1 meter away from the subject, it will see a linear slice of the subject that’s 1 meter wide and 1/128th of a meter high.

    Dave
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-10-26 08:45
    memooo,

    What you propose should work. Just make sure there's enough optical contrast between the subject and its background. For example, if it's a light-colored object, use a dark backdrop and light it from the front. Or, if it's a dark object, backlighting will provide the best contrast. In any event, you will always get the best results with controlled lighting, rather than with ambient lighting.

    -Phil
  • memooo2006memooo2006 Posts: 8
    edited 2010-10-26 09:45
    Thanks guys for the help.

    Dave,

    This is good news for me since the object will be levitated 30cm away from the sensor a wide view of 30 cm will certainly do it.

    Phil,

    The object is an iron ball 2 inch diameter which i think will shine. So I think I better dark up the background if I will end up using this sensor for such task.

    Memooo
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-10-26 10:31
    memooo,

    I know this is going to sound weird, but if the ball is shiny enough that you can see your reflection in it, it may well look dark to the camera. The reason is that you don't really see mirror surface objects, since there's no diffuse reflection from them. What you see is whatever background images the object reflects. And, because a ball is convex, everything reflected by it (including a front-lighting source) will look smaller than they really are. So, if you decide to use front-lighting against a dark background, make sure that your light source is big enough that the camera will always see its reflection, no matter what the position of the ball is.

    BTW, a 2" iron ball must weigh what, about 1.2 lb? That' gotta be one heck of an electromagnet you're using to suspend it!

    -Phil
  • memooo2006memooo2006 Posts: 8
    edited 2010-10-26 20:42
    Phil,

    I will think about this with i install the horizontal magnet..

    and yeah I need a lot of magnetic force to be able to levitate a 20 grams iron ball. wish me luck on that and still in the stage of building the magnets thu..
    and thanks again for your help..even though this is my first time i log into this forum but i really like it you guys are amazing..

    memooo
  • memooo2006memooo2006 Posts: 8
    edited 2010-10-26 22:08
    Phil,

    I am just wondering, do you have a sample program of how this sensor is used in C Language. I saw some programs you have but you were using other languages...This is actually my first time using this sensor so I am kinda exploring it.

    Thank again
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-10-26 23:23
    No, sorry, I don't do C, but others do:

    I'll also ask the folks at TAOS if they have any C code for this sensor. They do a lot of work with Microchip processors, so they might.

    -Phil
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