A fire robot

Thread Starter

Voltboy

Joined Jan 10, 2007
197
Hello..
Im kinda new at electronics but i want to do a new project that reacts to fire.
I want to do a robot that knows when theres fire (to do this i put a phototransistor with a infrered filter), and when it sees fire it goes forward until its really near from the fire.
I think that to make it go forward maybe could be by using a transsitor as a amplifier for a motor so depending on the current of the phototransistor it will make a motor run.
But I cant think of something to make it stop when its really near. Maybe with a inverted logic gate, but really I have no clue on this part.

If you have any idea or solution for this project just post it :)

Thanks
-Yoda
 

beenthere

Joined Apr 20, 2004
15,819
There are at least two problems with your approach that are going to make implementation a bit difficult.

1. Unless the fire is very small, like a candle, deciding where the fire is will be hard to define.

2. Defining close, as in where to stop the motion towards the fire, will be a challenge. Fuels burn at different temperatures, so stopping at some preset level of IR puts you in one fire, and 20 feet from another.
 

Thread Starter

Voltboy

Joined Jan 10, 2007
197
There are at least two problems with your approach that are going to make implementation a bit difficult.

1. Unless the fire is very small, like a candle, deciding where the fire is will be hard to define.

2. Defining close, as in where to stop the motion towards the fire, will be a challenge. Fuels burn at different temperatures, so stopping at some preset level of IR puts you in one fire, and 20 feet from another.
About the 1 i have no problem because I will not light a big fire.. I'll Probably use a candle. But about the 2 i thought same as you, thats why I need help because the robot needs to stop before the fire so it wont burn..

Thanks
-Yoda
 

mrmeval

Joined Jun 30, 2006
833
You can use two of what ever sensor you choose and a comparator which would tell either your motor controller or microcontroller which way the fire is. Tuning the sensor or microcontroller code to only detect what you want will take some effort.

If it can't see anything that matches you'd have to have it do a search which would be easier with a microcontroller.
 

beenthere

Joined Apr 20, 2004
15,819
If you can get the circuitry going to make the approach to the fire, possibly a thermistor can detect a rise in temperature and stop the robot outside the flames.
 

Thread Starter

Voltboy

Joined Jan 10, 2007
197
If you can get the circuitry going to make the approach to the fire, possibly a thermistor can detect a rise in temperature and stop the robot outside the flames.
yeah but as i said it is going to be a candle.. and it dont rise the temperature that much
 

Thread Starter

Voltboy

Joined Jan 10, 2007
197
Hey.
I tried to make the circuit in Eagle and here is it.
Both circuits are actually the same just that I need 2 so when, lets say there is a flame on the right, the right phototransistor will detect it and power the left motor so the robot will go to the right.
I just think this is too simple to work, its kinda stupid.
Please say what you think and if you know how to improve this just post it.

Yoda
 

Attachments

Distort10n

Joined Dec 25, 2006
429
This project was done by several students that I went to school with. It actually was a very involved project, both on the hardware and software level.
There was more to their project; however, the robot would nagivate a maze as well detect fire (candle) and extinguish it.
If I am up there over the next weekend; I will look in the library for their presentation. They may have a schematic there.
 

Thread Starter

Voltboy

Joined Jan 10, 2007
197
thanks alot..
I know most of people that do this project makes them able to navigate trough a
maze, but to do this I need a microcontroller and better sensors, etc. I cant spend more than like $30 on this project (im only 13 and im not gonna use all my savings on this project). Thats why i thought that the phototransistors would be good, i want the robot only to simply see the fire and extinguish it, without any obstacles.


-Yoda
 

RiJoRI

Joined Aug 15, 2007
536
How about using four eyes? One pair used as you have now, to detect and approach the flame, the second pair to detect proximity, stop the 'bot, and trigger the extinguisher.

--Rich

P.S. -- I do this from work, so I won't be replying 'til Tuesday...
 

Thread Starter

Voltboy

Joined Jan 10, 2007
197
How about using four eyes? One pair used as you have now, to detect and approach the flame, the second pair to detect proximity, stop the 'bot, and trigger the extinguisher.

--Rich

P.S. -- I do this from work, so I won't be replying 'til Tuesday...
How would I do with an extra pair of phototransistors to detect proximity?
 

beenthere

Joined Apr 20, 2004
15,819
You could probably use one, provided that the detection pair got you robot to accurately approach the fire. The extra PT would be an intensity sensor, and stop the robot at a "safe" distance from the fire. The output would most simply be fed to a voltage comparator. The comparator would change state at the "safe" distance.
 

SgtWookie

Joined Jul 17, 2007
22,219
This can be quite a complex project.

I'm afraid that your initial stab at the schematic won't "do it" for you. Your "'bot" would quickly get lost, and shoot off in an unpredictable direction.

It was a good idea to include protection diodes, but they should've been connected in reverse across the motor's connections to take care of the spikes.

I suggest instead of finding the center of the flame, that you find an edge of it; for example the left edge. You also need to find the base of the flame, which will require another pair of sensors (either infrared or phototransistors, I/R might be preferable). If the 2nd pair of sensors is relatively high, you can angle them downwards to detect the slant range (see your Geometry book).

A standard firefighting technique is to aim at the base of the flame, beginning at one side (left), and sweeping across towards the other edge (right). This is highly effective with water, light water, CO2 and other various types of extinguishers. If you simply aim at the flame, you will not extinguish it.

What method did you have in mind to put the candle out? Something cheap, simple and relatively un-messy might be to just maneauver an air or CO2-filled balloon above the flame - the heat will pop the balloon and the shock wave will blow out the candle. Beware of hot wax splashing! Always have an extinguisher handy when you're doing this kind of experiment, and set it up in an open area. Heavy-duty aluminum foil on a concrete deck/floor would be a good idea.

This kind of thing can certainly be done using analog circuits, but it would probably be a lot more helpful (and a much smaller parts count) to use a microcontroller such as a PIC, and small stepper motors.

You can scrounge stepper motors from "dead" floppy disk drives, printers, and the like. Finding deals on "unipolar" stepper motors isn't hard - but then you have to shell out money. The steppers you'll find in computer equipment will likely be the "bipolar" type, which are more difficult to control than the "unipolar" type - everything's a tradeoff. ;)

Get your idea down, and describe exactly what you want to accomplish.

Then break the project down into individual pieces - small enough so that each piece is easy to understand.

Just getting a stepper motor to run smoothly in one direction at one speed can be a significant challenge.

The way to eat an elephant is to take one bite at a time. Think positive! :)
 
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