ne of my early Mindstorms projects was to build a fire extinguishing robot. I did this using the parts I had at the time. It was based on a walker platform and used a pneumatic circut to “blow” the fire out when detected. It worked reasonably well with the provided light sensor. Recently, I discovered the PIR (Passive Infrared Sensor) from TechnoStuff. This sensor was built to detect infrared heat and seemed to be a good fit for my next project. I mounted it to my new FireBot in tandem with a standard light sensor. Together, they would do the job of detecting a flame.

A candle was used as the “fire” in this project. The sensor was set as a Light Sensor:

The code was straight forward.  When the sensor detects a value > 40, it “see’s” heat. In order to get accurate readings for this, it is recommended to take numerous readings (say once ever 20ms) and average them. This is to avoide variances in the sensor detecting other movement such as humans or other devices giving off infrared. As noted previously, the robot used both the PIR and a Light sensor together to detect the fire. By taking readings from both sensors and comparing their results to what would be expected when a flame is near, the robot was better able to detect the flame. To view the code, see the FireBot details page and download the source code.

The sensor worked well, but it is best to combine it with a light sensor. Together the two can be used to detect a fire or other object giving off infrared.

The quality of the product both in workmanship and function is top notch.  It is obvious that Peter takes time and know-how when creating each one of these. The visual quality of the sensor may make you think that this one came from Lego themselves if it wern’t for the TechnoStuff logo on the side…

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