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Author Topic: Project HELP. Wireless Fire Alarm system. IMPORTANT  (Read 1028 times)
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I am currently working on a project for my class. I am an electrical engineering student.

Basic idea for my project is to have wireless detectors installed on a floor for fire safety. In case of a fire the detectors will turn on and depending on where the fire is detector's LED light will turn green or red. Green meaning the path is safe to take for exit and RED meaning don't use the path because its going to lead to fire.

I want to figure our how to communicate this wireless sensors with a central station where I will get information about fire is and also I need to figure out how to send out message to all other detectors about turning green/red.

So which software/hardware do you think I should use for my project. Software most important.

I attached image to give you brief idea about my project.

Thanks for your help.


* central sys fire.jpg (111.48 KB, 852x657 - viewed 31 times.)
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I don't think you connected the grounds, Dave.
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Quote
So which software/hardware do you think I should use for my project.
For safety-critical applications, both must be robust, reliable and well-tested
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Hardware -- What about cost, an Xbee at every node may do the trick but that will get expensive. Something like the Jeenodes may be good, they are essentially an Arduino and wireless comms on one small PCB.

Then each node has to have battery backup.

Software -- no idea, DIY I suppose.

If this was for a real project the safety aspects would be enormous, for a class exercise maybe you can just spell out what you would do for the real thing.

_____
Rob
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I don't see anything IMPORTANT there - not to me, anyway.

From a human factors point of view I suggest you show a light if the route leads to safety and nothing if it leads to danger. In a real fire, people would not stop to think about which colour is which. Also you need to make sure they follow the line of lights in the right direction. With conventional fire exit signs this is done by the orientation of the sign - if you can see the sign, you are facing towards the exit. I suggest you do something similar with your line of LEDs - this might need them to be partially shrouded.

You need to have a reliable and robust control mechanism. Wires leading back to the fire supression control system would be the most obvious approach since this is where you will get your information about where the fire is.
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Good point about red/green/on/off, personally I would be flat out telling the difference in colour on a good day, let alone in the panic of a fire.

______
Rob
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You should also consider colour blindness - some people cannot distinguish red/green. And visibility in smoke.
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That's right, in fact red/green colour blindness is very common in males. I hate those bloody battery chargers that have bi-colour LEDs, I can never tell when the batteries are charged smiley

What I don't understand is that probably 90% of engineers are male, so how come this is so common? Surely someone puts there hand up and points the problem out.

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Rob
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IMO, I would consider hard-wiring.  Maybe even PoE so you have a single data and power line.  Or CAT5 UTP delivering serial + power.

Give each node a zone ID/address and send the same data to each.  Then, your data consists of an array of zones/addresses and a flag (safe/unsafe).  This simplifies your wiring to where it can be a bus, or star, or daisy chain.  As long as each node gets the data and is assigned the proper address (written to EEPROM?), you're good.

You might try keeping with the green/red idea, but also using a secondary element, like blinking or chasing, which might help with both intuitive action and color-blindness.

It might seem kinda "sci-fi" and superficial at first, but doing a chase pattern down corridors could help steer folks toward a safe path.  Delay each successive node by (e.g.) 100 ms, so the lights blink 'toward' the exit .. kinda like you might see on a runway at an airport.  It would be easy to do with an addressing scheme, where maybe the low three or four bits of the address get used as a delay factor.  Then you can turn on a safe zone, and all nodes in that zone delay by (100 * (addr & 0x07)) for instance.  Hope that makes sense.

Of course, each zone could be controlled by a single Arduino, where you use 8 outputs to drive LEDS (or transistors that drive LEDs) instead of dedicating a device for each set of lights.  (Maybe that's what you were originally thinking of..)  Then you can still chase by delaying the pins in succession -- maybe by using PORT commands and bit shifting.

Unsafe zones (or routes that lead away from an exit) can be marked by flashing all lights in the zone red, simultaneously.

If you were confronted at a T, and one way had flashing red lights, the other green lights that chased down the hall, which would you instinctively follow?  Even if you were colorblind, I think the effect would be sufficient.
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