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Wifi tracking stage light

Discussion in 'Robotics & Mechatronics' started by Mosaic, Oct 2, 2014.

  1. Mosaic

    Mosaic Well-Known Member

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    Hi All:
    I am considering a project which purports to use RFID wifi transmission data to track a person on a stage for a smart stage light (DMX) to auto track.

    I am not clear on how to access the position data from the wifi transmisssion. Also, I need to figure out the DMX protocol to instruct the light to move. thsi is a start point. http://en.wikipedia.org/wiki/DMX512

    My plan is to access this data, compute from cartesian to polar coords and then convert to the DMX protocol to instruct the Fixture to aim at the targeted person.

    Any thoughts?
     
  2. alec_t

    alec_t Well-Known Member Most Helpful Member

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    What provides the position data that is to be transmitted by wifi? Don't RFID systems usually detect just presence rather than position?
     
  3. ronsimpson

    ronsimpson Well-Known Member Most Helpful Member

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    Maybe you can put a RFID chip in every ones shoe.
    Put 100 RFID antennas in the floor.
    (or the reverse---Put the RFID antenna in the shoe and the chips all over the floor)

    When person 5 is in location A7 then point light 5 at A7.
     
  4. dave

    Dave New Member

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  5. Mosaic

    Mosaic Well-Known Member

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    This is relevant
    http://www.ekahau.com/real-time-location-system/technology
     
  6. alec_t

    alec_t Well-Known Member Most Helpful Member

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    So, looks like you'd need an IR beacon sytem in addition to the patented RFID system to get the claimed location accuracy of 1 metre. Without the IR the accuracy claimed is 8ft - 15ft (which wouldn't seem adequate for stage light tracking).
     
  7. Mosaic

    Mosaic Well-Known Member

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    looks that way.
     
  8. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    DMX is pretty trivial (just a simple serial data stream) - your problem would be the location part - which I suspect is going to be VERY difficult.

    Presumably you would need to buy the equipment from the site you posted?, and they could then provide you with details of how to use it.
     
  9. Mosaic

    Mosaic Well-Known Member

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    My worry is that the real time location is a closed system and I won't know how to tap into the data stream or what the protocol is. The application isn't meant to require a PC as the interface to the RFID data. I guess I need to write the RFID supplier first.
     
  10. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    As it's a WiFi based system, it's VERY likely PC based - and probably requires considerable processing?.
     
  11. Mosaic

    Mosaic Well-Known Member

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    Hmm, since its a proof of concept exercise, I suppose I could use a laptop for now to prove functionality. Perhaps later on press a linux Raspbery pi into the service.
     
  12. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    As an owner of three Raspberry PI's I'm dubious about it having anywhere near the required capacity - but I'm only assuming the requirements are high, without information from the suppliers of the location system we don't know what's needed.
     
  13. Misterbenn

    Misterbenn Active Member

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    Sounds like you're trying to make an auto follow spot.
    DMX is easy there is an arduino shield and library for DMX control which I've used with great success.
    However I suggest you likely need a good level of accuracy to get smooth operation, in the range of 1/2 a stride.

    Getting the location from wifi would be very hard. But I wonder if you could measure the time for the actors wifi signal to get to points (at least 3) in the room and then use calculus from there. of course reflections will cause all types of issues, and really you don't need wifi any radio transceiver will work, but you'll need very accurate timing pushing you to fast and synchronised clock speeds. Wifi might have the benefit that you can use server time but latencies will cause huge issues.
     
  14. misterT

    misterT Well-Known Member Most Helpful Member

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    Last edited: Oct 7, 2014
  15. Mosaic

    Mosaic Well-Known Member

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    I am interested in that arduino solution for DMX control. Do you have a source?

    I am in contact with an RFID, wifi firm who has outfitted a stage to track RFID tagged footwear so that fashion models are tracked and trigger thematic lighting to match their wear.
     
  16. Misterbenn

    Misterbenn Active Member

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    http://store.arduino.cc/product/T040060

    And you think they'll tell you how they did it??
     
  17. misterT

    misterT Well-Known Member Most Helpful Member

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    Do they really track the models with automated spotlights, or do they just read the tag when the model enters the stage, and then automatically set the pre-programmed lighting?
     
  18. Mosaic

    Mosaic Well-Known Member

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    They did say it would require a special setup to do it . We'll see if they are willing to help out.
     
  19. misterT

    misterT Well-Known Member Most Helpful Member

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    To do what? Read my post #16 again.
    .. and what exactly are you trying to do?
     
    Last edited: Oct 9, 2014
  20. Mosaic

    Mosaic Well-Known Member

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    The auto follow spot.
     
  21. misterT

    misterT Well-Known Member Most Helpful Member

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    Does the company you have contacted a product that does this?
     

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