Advice Needed - Real Time Tracking Pipe Dream

[azecraze]

Ok, I'm new here and this is my first post......

I have a project I am still in the planning stages of and need advice on a certain aspect of it.

The project involves the use of servos/steppers to control spotlights in a theatre environment.
I currently using "Intelligent" moving lights but I want to break out from using them due to a number of reasons and make something up that works the way I want it.

Anyways, I am thinking of having some sort of auto tracking device on a performer so that the spotlight will follow them..... the servo/stepper stuff I can handle ok, but I need advice on what type of tracking device would be best to use ( if any at all!)

So the performer has a little clip on badge with a xmitter... and I have a RX on the spotlight... then the spotlight will just track the performer

The working range would be approx 10m with a maximum of about 20m .... would need to be NON line of sight capable, else the performer moving may disrupt it.


So I am thinking along the lines of IR, Laser, RFID or whatever.

Any thoughts on this?

 

[mneary]

Your performer is wearing a wireless microphone, no?

 

[Torben]

Well, IR and laser are both out right off the bat, since you want non-line-of-sight. That leaves RF and ultrasound. Ultrasound would have to be fairly beefy to make it 10-20 metres and still be reliable, and I understand that RF is a little difficult to get a good positional lock on in such a small area. RadioRon would be the guy for that question, though.

I think similar systems have been explored on this forum in the past. Try the advanced search function; you might find something useful.


Good luck,

Torben

 

[Mikebits]

How about using floor mat switches. Light can be set to track based on which switch was last depressed. Only flaw is if someone steps over switch.

 

[Roff]

Google "video camera tracking". Perhaps the lights could de servo'ed to the camera.

 

[azecraze]

Thankyou for all your replies....

After taking the advice of "Roff" I came across some little hacks at instructables.com that may be the best thing.....


Floor mats are definitely out...

Thanks all...

 

[Slowmo]

Thermal imaging infrared camera connected to PC which would then analyze received images and give commands to servos to position the spotlight. But I don't know if such a system is available somewhere and it will not work if person goes behind an object.

 

[AllVol]

Thankyou for all your replies....

Here's one more: How about reflecting the spot's own light back to a guidance detector made of a solar panel, photo-transistor or photo-resistor array? Since the spot-lit performer would be the most brightly lit object, feeding back some of the light should not be a big problem.

Just a thought.

 

[ste5442]

Radio is probably best left alone.
With only a single transmitter (on the badge/clip) and a single receiver on the lamp you could only narrow the position down to a radius determined by the signal strength. You could argue that the lamp will be pointing at the stage limiting this to a field of view of 180 degrees but without at least another receiver in a different location you are stuffed.

Most radio modules have an RSSI (received signal strength indicator) output which could be used - one tx on clip/badge and two rx (one on either side of the stage) - from the RSSI of each of the two rx you could roughly work out whereabouts on the stage the tx is. you could add a third rx to the lamp to get distance from the lamp.

This would work and should be cheap.

One thing you should note is that if you use a transmitter in the ISM band you are risking members of the audience changing the lamp position with their car keys or whatever ;-)

S

 

[Torben]

Thermal imaging infrared camera connected to PC which would then analyze received images and give commands to servos to position the spotlight. But I don't know if such a system is available somewhere and it will not work if person goes behind an object.

It might also have problems in a stage environment, where the lights often cause temperatures on stage to be much higher than you might expect.


Torben