Vex Flame finding

Anyone have any ideas on how to make a program to sense a flame and make the robot drive towards the flame in this scenioro the flame will be about 2 inches off the ground and the robot must sense the flame then travel close enough to put the flame out. We have the ability to use only 2 light (not he line followers) sensors. Thanks for any help. this is part of the maze question (see vex maze by charlie1218)

many articles of this in servo magazine (well flame sensors anyway)
you should order that copy, i forget which one but you can find it on their website

Using filters to let through frequencies that are strong in a flame, but are weak in the ambient light might help; if you know in advance what the ambient light’s and what the flame’s spectra will be (and if you allowed to use filters).


No non KOP

An oil burner cad cell may be useful.

If you put a finger sized tube about 2" long over the stock Vex light sensor it can find a candle flame at about 2 feet. (Electrical tape works well) The tube blocks out the ambient room light. You’ll need to mount the sensor at the height the flame will be and make sure that it is level with the floor.

You will also need to calibrate the sensor to the standard room light at the event so you can tell when the flame is present.

A black, matte finish inside the tube cuts the inner light bounce down. One thing you can try is to mount the sensor in the bottom of a black 33mm film can. You can then drill different sized holes in the cap to experiment with.

CdS Photo resistors (5-Pack)
$2.99 Model: 276-1657

Would be a place to start if you want to try building your own sensor. Their are different sizes / types, so it will take some experimenting to get it to work.

Good luck!

I agree with this approach. It is the easiest method possible and I’ve tried it with a BOE-Bot before with success. Good luck!

Remember, no non VEX KOP (kit of parts). We have 2 flame sensors btw

Okay basis of a flame emits lots of IR

So using “line tracer” which are actually IRs, make a nice tube around the IR window to block out ambient light. Maybe want to tweak/mod it to disable the IR emitter.

Similar to the above post on putting a tube around light sensor but I think IR may be better suited :slight_smile:


He can’t use anything outside a VEX starter kit. (Other than the light sensors and some extra VEX sensors.)

However, there are some black rubber spacer-type things (axle blocks and the like) that might work, if bolted together…

BTW these are not just the line sensors, but those photoelectric sensor modules aswell.

Remember, no non VEX KOP (kit of parts). We have 2 flame sensors btw

I figured if it was an event that had flames that there would be some level of slack from the “ONLY VEX KOP” rule.

1)Take the nut driver tube and cut the narrow end off. This will leave you with the wide end that just covers the sensor and about 2" of focus tube. At $4.99 each, this is not a cheap solution.

2)Take the rubber mat and wrap four turns around a 1/2" dowel. You are trying to get the little nubs to fit into the mesh. Secure with the black zips.

3)Take two or three intake rollers and using the black zips make them into a tube. Drill a 3/8" hole in the center.

Mounting is up to you.

Post a picture of what you finally do.

NO slack, only KOP

set up the 2 light sensors at the rough level of the candle and as far away from eachother as the dimesions allow. The 2 senors should face slightly inward if possible
Compare the readings of the 2 sensors and give more power to the motor on the same side as the reading with more light (I believe that lower #s are bright light but I am not sure)
This should center you on the candle - Put in code to stop when you cross the white pad around the candle otherwise you will run right into the candle

I recommend trying to narrow the range of vision for the sensors. If you can only use KOP see if a couple lock plates (without the center piece which actually put the axle through) gives you a wide enough range… I think that hole in the bearing flats is a little too narrow.

Tell me if it Works! and good Luck!:smiley:

do you mean you can’t even modify the parts?:eek: ouch!

We cant cut, twist and do whatever, but we cannot add pieces.