View Full Version : Looking for the Right 'Device' for a game of TAG.

Brian Carpenter
04-11-2007, 12:19 PM
I have 2 robots that can move around in various sequenced patterns. The goal of the bots is to detect via low rf frequency the other bot and try to 'tag' the bot. I am not familiar with ultasonic, but was thinking that this is the route that i would take.I was looking at the PING by Parallax and basicly it has a 'transmitter' which sends the chirp and a 'reciever' that listens for the echo. Is this correct? So if i were to build a board with a reciever at say the back end and a transmitter at the front both pointed horizontally in opposite directions and had one mounted on each bot, transmitter pointed forward.

one bot could then always listen on the reciever to see if it is being hit from behind while 'firing atthe back end of the other bot trying to hit it.

the only other thing that concerns me is that i am not sure what the ultasonic pattern is like. I am assuming that it is conical, emitting from the device, but what is the spread and distance. Is the attached depiction realistic?


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Phil Pilgrim (PhiPi)
04-11-2007, 12:55 PM

I think you'd be able to control the pattern better (via baffles, if necessary) if you used IREDs and IR detectors. Plus, the circuitry would be a lot simpler.


04-12-2007, 07:49 AM
How does IR work outdoors ?
I would think as long as the sun is not shining directly on the receiver (shielded), it would work.
Have you (or anyone) tried IR outside ? I though some of the car alarms were IR.


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Phil Pilgrim (PhiPi)
04-12-2007, 11:08 AM

Hmm, good question. Using a modulated system will be essential, and may be enough, so long as the detector doesn't saturate.

You'd probably need an IRED you could burst modulate at a few hundred mA or more. In addition to an "awning", a narrowpass optical filter on the detector would help to keep it out of saturation from the sunlight.