Let's Make Robots!

Temperature Sensor?


Right now i am planning to build a autonomous robot that puts out fires. It will go up to a tiny fire (about 4 inches) and then drop a tiny bucket of water (2 1/2 inches wide, like the ones that came with the old version of robosapien) on the fire. The bucket will be put on a platform attached to a servo. when the servo turns the bucket will pour. I am going to do this all with picaxe. I know how to use picaxe, and coding in basic.  Anyways what my real question is, Is there a type of sensor that i could use to find the fire and stop before it? Could I use IR somehow?


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Thanks for telling me that the IR would not bounce off the flame. The thermal array sensor looks like it might work,but it is kind of expensive (110$). 

what about the thermal array sensor? http://letsmakerobots.com/node/3888 

though the description says it detects a candle light at a distance of 2 meters at most, but if you're working with bigger flames or at short distances it might be the best idea. 

Sorry, I worded that last thing wrong

The IR sensor would not be for finding the flame but more for stopping in front of the flame. Y'know so the robot doesn't get torched. What i meant was would the IR sensor recognize the fire just as it would a brick wall in front of it? 

I'm thinking of having the pyroelectric sensor find the flame, and the IR to avoid obstacles on the way to the flame.

thanks for the responses though. I laughed when I read about burning ants with a TV remote. funny stuff.

The IR ranging sensor will not pick up a flame. Simply because the IR light from the sensor will not bounce of off the flame.

Maybe it will bounce of off the candle, or the house that is on fire. But not the flame. Light (and IR) will beam right through a flame.

May I suggest a simple thermometer on a probe?


I was thinking about this and remembered that if you lose the sensor bar from your Wii, you can just use candles, so I did a google search and came up with this, hope it helps:  http://www.wiicentre.com/the-10-coolest-wiimote-modifications-151/

scroll down to number six. 

Oh I forgot, do you think that the common IR sensor (like the one in the "start here robot"") would be able to detect a flame in front of it?
If your using it as a fire sensor then you will probably have to connect it to an analog input. The IR commands are communication commands. The other sensors might detect it but will more likely cause your robot to extinquish the TV remote as the wavelength for radiant heat is completely different to IR used in remote controls. Otherwise kids would use a tv remote to burn ants rather than a magnifying glass on cloudy days.
The IR sensor in the "Start Here" robot is a distance measuring sensor, so that probably won't be any use for detecting a flame.  The usual TV-style IR receiver unit will only detect modulated IR signals.  They work that way so that they don't suffer from false triggering due to IR light in the environment.  A bare IR photodiode might work, you'd have to get one and test it.

Thats cool!

When it is used with picaxe do i need any special commands or can I just use the common IR commands?

I presume those Picaxe IR commands are for communicating over IR remote-control channels -- is that right?  If so, then no, you won't be able to use those commands.  Normal TV-type IR control systems use IR light modulated at 40kHz.  IR from a flame is a different wavelength, and of course won't be modulated at 40kHz.  You'll have to connect the pyroelectric detector to one of the spare parallel I/O pins, program it to act as an input, and then read the pin.