proximity sensor with arduino

Forum 2005-2010 (read only) Hardware Interfacing
1

hi guys,

i'm a newbie in arduino, and i was asked to assemble a simple installation consisting of areas in which, when people get in, a sound is played (it will be one single sound file). it will probably be around 10 of these areas. the sensor should capture one's presence within a distance of 1-2 meters. what kind of sensor should i use for this installation, IR? sonar? can i hook all of them in one single arduino board? and to play the sound, should i use media players? thanks in advance!

matt

2

What is the shape of the space? Is it multiple rooms, or one space with very little separation?

A common way to detect the presence of a person is a Passive Infrared (PIR) detector. These detect a small temperature change between a background and people. It's the sort of thing you get in the new air fresheners, and burglar alarms.

If the areas have door ways, you could use Infrared 'magic eye' beams. The idea would be to transmit Infrared light, and detect it, then when it is broken, then someone has walked through. The sort of parts are used Infrared Remote Control in lots of domestic electronics, like TV's, DVD players, etc.

A downside is that it might become awkward to tell the difference between people moving in different directions, so a bit of care in the physical set up would be needed.

Ultrasonics is feasible, again like a burglar alarm. I have a concern about different receivers being a bit confused by other transmitters.

Have a google, and you'll find a bunch of circuits.

It might be a bit much for one Arduino, but feasible with a few.

HTH
GB

3

depends on your installation: you might try PIR sensors

4

Can I just be clear about one thing...

These 10 spaces and the sound: Am I right in inferring that you want a "logical OR" situation? I.e. it doesn't matter which or how many of the spaces are "invaded"... you get the same sound?

As the how the sound is made: The Arduino, in simple terms.... I like "simple" (matches my nature).... can close a switch. With the silicon intelligence of a 1980s PC, it is quite capable of cleverness in the closing, i.e. close for "x" seconds, not close again until "y" seconds have passed, etc, etc, but it is still, basically, a switch closure. That closing switch can be wired to lots of things.... a doorbell ringer might suit, for instance.

What sound: If you just use the Arduino to close a switch, we're done with the sound bit. Probably best to start there, as your sensors are not simple. But remember that the Arduino is clever. You might use it to generate the sounds that emerge when the switch closes. Maybe even "play" a short "audio recording". Subject for another time, another thread.

Sensors: PIR is probably going to be your best bet, if I guess your application right. Ultrasonic might "do", but as someone else said, they might confuse one another.... but!... can you mount the sensors on the ceiling, looking down? That might have all sorts of advantages, and might bring ultrasonics back into consideration.

Sparkfun has a little PIR, 0- 255 inches, $25

But their PIR is only $10, and I'd lean towards PIR anyway...

"At the risk of being totally boring...." (as Mrs. Wilknson says in the magnificent Billy Elliot musical), what does the Arduino bring to the party? Why not just connect some PIRs to a doorbell? Perhaps if you expand on the "why Arduino" side of things, forum members can help refine your design.

5

hey guys, thanks for the replies.

let's see if i can clarify some things. the installation consists of 10 or some spaces like changing rooms, which are round spaces, in a department store. a sound (like a shower sound effect) must be played every time a person gets in the changing room (which must have something like 1 square meter area). the sound should be the same in every changing room, and each one has its own speaker.

i can mount the sensors in the ceiling or close to the entrance of the changing room, so i'm guessing my best bet would be PIR or IR magic eye beams.

i thought about arduino in order to manage this several sensors and make it play the sound in the changing room which a person got in.

hope this is a bit clearer now.. thanks for all the help, everyone :wink: