next topic »

[on:]

Hello everyone,

I am interested to make something as follows:

It's for Airsoft games, when players need to search some object, ans when they get close to that object, then the 'meter' beeps.

So, one team needs to search an hidden object on the terrain, that is 'interacted' with an 'object meter' that the team gets.
The 'object meter' starts beeping when they get close to the object that they need to search, and always beeps faster and faster as they get closer.

It's like the game that kids play when they search a hidden gift, and the friends say "Hotter, hotter,..." when he gets closer to the gift.


So let's say the object and object meter are connected via an xbee to each other. The Arduino must detect when the object meter is for example 10 meters from the object, to generate a beep.

Will that be possible with an Arduino? How?


Regards,
Tibo

EDIT: I just looked at some proximity sensors, but the range is to limited.

[Reply #1 on:]

not trivial

some ideas to try
- xbee and its rssi signal strength
- using gps (hidden box sends its coordinates over wifi ) expensive
- wifi itself with strength
- ultrasound pulse ?

[Reply #2 on:]

ultrasound or PIR sensor would be my guess

[Reply #3 on:]

Just use an SRF02 ultrasonic range finder.
Your loop should:  Make a measurement, convert to inches, make a beep, and then do a delay proportional to the distance.
Put 30 ft wires on the beep speaker (or the SRF02), so zeroing in on the sound will not make it too easy.

[Reply #4 on:]

only thing with a ultrasonic, or most other sensors, is that it wont be 360deg. you could make a sonar out of a ultrasonic with a servo:P

[Reply #5 on:]

Thank you for the replys!

Although, the range is too limited of the ultrasonic and PIR sensors.
Maybe I did have to mention this in my first post, but the range needs to be around 400meters(it's on big terrains).

So maybe as robtillaart said, using a gps, wifi or xbee would be a good idea, as this will increase the range much more.
What do you think?

[Reply #6 on:]

How about a radio-controlled, swept-pitch, beeper?   Each team gets a cheap key fob type R/C transmitter.  Pressing immediately
causes a beep on the distant unit.   The one doing the pressing gets an immediate distance clue due to the slow speed of sound.
The low to high frequency squeal-like sweep is helpful because different pitches have different directional and reflective effects.
If there's a competition, the team/person who uses the fewest beeps wins.

[Reply #7 on:]

Yes! That's most likely what I want to do! Thanks!


Can you explain this a little more, I do not understand it all?:

The one doing the pressing gets an immediate distance clue due to the slow speed of sound.
The low to high frequency squeal-like sweep is helpful because different pitches have different directional and reflective effects.

It would also be nice if I attach a buzzer on the transmitter, and the buzzer starts buzzing faster and faster when they get closer to their objective.
Is that also possible?

[Reply #8 on:]

the buzzer starts buzzing faster and faster when they get closer to their objective.

That would make things too easy, I would think.  You walk in a little circle and see which direction gets you closest and go that way.
Besides, if it would work with GPS that would make it quite complex.  Measuring the delays of radio responses is similarly tough (radio moves at 1 foot per nanosec, necessitating a 1GHz counter, the electronics for which is a specialty art in itself).

The one doing the pressing gets an immediate distance clue due to the slow speed of sound.

The speed of sound is about 340 meters/sec, so the delay between when you press and when you hear is a very observable, and if you're good, quantifiable one second.
When you're 100m away the delay is only a third of second, quite noticeably quicker.
Volume wise it would also sound like it's about 300m away, especially if one has heard the beep up close first to guage the volume attenuation.
Also, if you happen to be approximately facing the sound, your two ears would give your brain a pretty good clue of the direction.

The low to high frequency squeal-like sweep is helpful because different pitches have different directional and reflective effects.

In the woods, or other rough terrain, if you used only one frequency beep, it might get confusing since that beep would reflect off rocks, trees, buildings, etc.
Maybe you want it not to be too easy, and pitch sweep is an adjustment.
A changing frequency is more comprensive, reflecting differently on different objects.  I think bats, dolphins, and whales all use some type of squeal.

[Reply #9 on:]

Thanks for explaining it all!

I'm gonna do something like you said.

Is it possible to make the beeper that I add on the transmitter, beep faster and faster as they get close to the objective? It would be a nice feature.
Maybe it is to difficult to make it beep faster and faster as they get closer, because like you said, the distance needs to be measured. Or are there other ways to do it?