Heat Guided Missiles

[5614]

firstly, i want you to know, i have NO idea what 'subject' to put this under...

i put it in computers because i thought the answer may be something to do with computers

 

Heat guided missiles, or infa-red missiles:

[they're the same thing!]

 

i was just wondering how IR guided missiles work. they are quite old technology now, so even if the modern ones do use computer and GPS [global positioning satelites] then how did the old ones work? i was just wondering because i was hoping to incorporate IR 'seeking' electronics in a project, its not a missile! but it would be a cool add-on to any electronic project!

 

cheers [a break from the normal 'thanks' or 'thnx'!]

[Cap'n Refsmmat]

http://science.howstuffworks.com/sidewinder5.htm

[5614]

ah, should of checked out that site, i'll read it lata! thanks

[YT2095]

buy a cheap PIR detector

[5614]

what PIR, IR = infa-red, whats the P?

(is it Passive Infra-red?)

 

i was wondering about the guidance control electronics, which process the information from the seeker and calculate the proper course for the missile.

 

could this be incorporated into a simple electronic project? or is a whole computer system which is not worth attempting to build for a 'small-ish' project?

[YT2095]

I made one for a robot once, it was an IR detector mounted on a stepper motor.

as the motor moved from left to right (in 500 steps) it would increase a counter, and when it got to 500 it would move back right to left and decrease the count. when it "Saw" an IR source, it would pass this number to a control register and display what direction the source was in, that then was passed to driver board to control the wheels, the unit would then move towards the source, constantly tracking it as the sensor moved. of course all this takes longer to explain than the actual movement and tracking takes place, I`de get 2 sweeps a second, not bad considering

[5614]

is PIR Passive Infra-red then?

 

this robot sounds a bit advance for a mini-project which i was thinking of, maybe i could do it as a bigger project, does it look like your remote control reciever for your robot project [on your site] where it will work, but is a bit too complicated for an on-looker to work it out!

 

how big was it, how did you get it to "see + follow" an IR source?

[YT2095]

it is indeed Passive Infra-Red.

 

I just explained how I got it to "see"!

the whole robot was only the size of a shoe box, and that remote board on my site is for a different bot.

[5614]

when it "Saw" an IR source, it would pass this number to a control register and display what direction the source was in, that then was passed to driver board to control the wheels

 

yes, but HOW was this done?

 

saw IR source = PIR or IR detector? whats the differnce?

 

"control register/display" = how does it work? what was it? a IC chip or what?

 

"passed to the driver board to control the wheels" = how was this done [obviously a motor, but how was the passing done?]

[YT2095]

PIR`s tend to work more with heat, regular IR detectors like the ones in your TV fro "seeing" the remote control, work on Near Infra-Red bands as opposed to Far IR in the PIR detectors, that why the sensor`s called a `Pyro`.

 

a stepper motor works in stages, a sequence of pulses in the right order make it turn a fraction of a degree per stage, these pulses are put into counter IC`s (specificaly 3x 74161s).

the output of which are passed onto a pair of 74373 latches, that lock and hold that number when trigered to do so by the IR detector.

it`s really quite simple!

 

imagine turning your head left to right to left again etc... in a dark room. then you see a candle, your head stops and says to your body, "the candle is on my left" so you move towards it.

[5614]

ok, i didnt know about IR and PIR frequency ranges

 

and the 74161 / 74373 IC chips answer most of the question, cheers