Wifi tracking stage light

[Mosaic]

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. https://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?

 

[alec_t]

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

 

[ronsimpson]

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.

 

[Mosaic]

This is relevant
**broken link removed**

 

[alec_t]

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).

 

[Mosaic]

looks that way.

 

[Nigel Goodwin]

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.

 

[Mosaic]

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.

 

[Nigel Goodwin]

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.

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

 

[Mosaic]

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.

 

[Nigel Goodwin]

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.

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.

 

[Misterbenn]

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.

 

[misterT]

Maybe easieast would be a transmitter in persons pocket and directional antenna in the light that searches (and tracks) for the direction of transmission. Or many antennas around the stage to scan the location of the transmitter.. the more scanners, the more accurate system.

http://en.wikipedia.org/wiki/Direction_finding
http://fpvlab.com/forums/showthread.php?8331-Antenna-Tracker-Arduino-powered-no-GPS-needed!
A review of antennas for indoor positioning systems

 

[Mosaic]

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.

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.

 

[Misterbenn]

**broken link removed**

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.

And you think they'll tell you how they did it??

 

[misterT]

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.

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?

 

[Mosaic]

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

 

[misterT]

...it would require a special setup to do it.

To do what? Read my post #16 again.
.. and what exactly are you trying to do?

 

[Mosaic]

The auto follow spot.

 

[misterT]

The auto follow spot.

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