IR Missile head

>>33524383

there's literal rotating mirrors and shit and measuring amplitude and frequency and shit and it makes my brain hurt.

>>33524383

It doesn`t know anything, it just makes a wild guess

>>33524383
THE MISSILE KNOWS WHERE IT IS BECAUSE IT KNOWS WHERE IT ISN'T

>>33526528
Beat me to it, fucker

lots and lots of kraut space magic.

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>>33524383
you can take years of engineering courses to answer that question OP. its called PID control

https://www.youtube.com/watch?v=UR0hOmjaHp0

>>33524383
Crazy moving parts and computer chips and shit

>>33524383
Older missiles have a spinning telescope mirror system in front of the IR seeker and a computer that can combine the angle of the telescope and when the target appears/disappears to figure out a tracking path.

Newer missiles have two rectangular seekers arranged in the shape of a cross, and images detected at the edges can signal the computer to correct course until the image is at the center of the cross.

>>33526528
/r/ing pasta

>>33526571
>you would never adjust your gains

I'm not going to make it.

>>33524383
Imagine you are riding a bicycle. You are the guidance system and in order to maintain balance you must constantly adjust for minute changes in overall balance.

In the case of the IR system, the guidance system is given an IR source and must keep the IR source in the middle of its sensor. If the IR source moves away, the guidance sensor will command the control systems to adjust towards the IR source.

Example:
A simple 2D scenario in which 1 denotes IR source, 0 denotes no IR source.

0-1-0 IR sensor has IR source in middle of seeker. No flight adjustment needed.

1-0-0 IR sensor detects IR source moving away to the left. Guidance now commands control systems to adjust left.

0-0-1 IR Sensor detects IR source moving away to the right. Guidance corrects right.

>>33526758
The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't.
In the event that the position that it is in is not the position that it wasn't, the system has acquired a variation, the variation being the difference between where the missile is, and where it wasn't. If variation is considered to be a significant factor, it too may be corrected by the GEA. However, the missile must also know where it was.

The missile guidance computer scenario works as follows. Because a variation has modified some of the information the missile has obtained, it is not sure just where it is. However, it is sure where it isn't, within reason, and it knows where it was. It now subtracts where it should be from where it wasn't, or vice-versa, and by differentiating this from the algebraic sum of where it shouldn't be, and where it was, it is able to obtain the deviation and its variation, which is called error.

Copying my posts I made in the /g/ thread...

There's a difference between tracking a target and guiding to a target. There's also a difference between "IR sensor" and "imaging infrared seeker". Most modern IR seeking missiles use an imaging infrared seeker which is essentially an IR camera on a gimbal. Since you have an array of pixels to work with, you can do image processing to detect movements of a target and identify a target from background clutter, countermeasures, etc. So in your "plane turning left" example, the seeker would run its onboard image processing and determine that its target is moving left and command the missile to steer accordingly.

Imagine you have an array of infrared pixels comprising your seeker. If the total field of view is large, then each pixel's FOV is presumably large. There could be an entire airplane in that one pixel and you probably wouldn't guide to it because there's no way of knowing if it's your target or some sort of background source, etc. But if the FOV is narrow, each pixel's FOV is small so your airplane now shows up as a pixelly-looking airplane shape which your image processing algorithms should be able to identify as an airplane. The tradeoff is that a narrow FOV means that if the target is very nimble it can jump out of your FOV before you can compensate.

>>33524383
t. Dong Cheng

calle calle

>>33524383

Basically, pattern identification and self-optimization.

>>33526528
>>33526758
>>33527003
https://www.youtube.com/watch?v=bZe5J8SVCYQ

>>33524383
That blue-ish mirror spins rotates around at an angle so it can triangulate where there ir signature is coming from based on the angle of the reflected ir signal when the mirror is at a know location and angle

>>33527007
What happens if there are multiple planes? Would the missile be able to tell which IR source was the original target?

>>33526571
> PID control
> years of courses
Uh huh. Maybe if you don't know basic algebra

>>33527361

Yes. The launch platform initializes the missile with where the target should be when the seeker turns on. Some missiles can even turn their seeker on to lock onto the target before being launched.

Modern sensors can detect the strength of the signal, and it's direction. This is more than enough information to determine the path of the target and make an interception. Older sensors only tracked the direction, but were still able to intercept targets.

>>33524389
>>33526954

Not any more. In the old days they used a very, very simple system where the sensor was fed light by a rotating mirror. When at the brightness was uniform it was faceing the target. When in some parts of the rotation it was brighter then others, the missile turned.

This system was dirt simple and cheap, and made the sidewinder and the shitty Russian copies of it very effective.

Modern ones are basically a camera. The IR sensor looks out at all the sources of IR energy ahead of the missile and compares them to a database of target silhouettes. It is smart enough to say "whelp, that's the ass end of a target aircraft. I'd best adjust my course to aim where it will be based on calculated vector. "

>>33527007

>>33527449
The image recongtion also serves to allow the missile to ignore things like flares in most cases.
This pretty much covers it.

>>33526528
Came here to post this

>>33527430
That's calculus, but yeah.

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>>33527430
you need to know laplace transforms, retard.
all of that "basic algebra" is hardcore differential equations
>>33528186
its diffeq, not calc

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>>33524383
Anti-air missiles? They mostly use proportional navigation to aim in front of the (moving) target by the appropriate angle to maintain a collision course.
https://en.wikipedia.org/wiki/Proportional_navigation
https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_range

So, imagine you're a Somali pirate driving a speedboat, headed East towards the shipping lanes hoping to seize and ransom a cargo ship. Directly ahead of you, you spot a ship of uncertain size and distance, but over time you notice the blob on the horizon moving to your left, indicating it is moving Northbound. Now, if you turn right directly toward the ship, it will keep moving North and you will need to keep turning left as it moves further and further - leading to an inefficient, curved, indirect path to the target. It would be better to turn PAST the target's bearing until you are on a straight collision course, which is indicated by when the absolute bearing to the ship stops swinging North and remains constant (a state known as "constant bearing, decreasing range" which is telltale of a collision course).

Missiles steer in this EXACT SAME WAY, but in three dimensions instead of two. If the target changes course, the missile simply recognizes the new change in bearing and steers until the bearing ceases drifting once again.
>>33527767
>When at the brightness was uniform it was faceing the target. When in some parts of the rotation it was brighter then others, the missile turned.
Not quite. See above. The missile didn't seek to put the target in the center of the seeker's axis, so much as simply keep the target's bearing from drifting. If the target was 15 degrees off-axis but remaining there, it would continue to fly straight.

It's also worth noting that the seeker was gimbaled and gyro-stabilized by the mirror's rotation, so the seeker's axis would remain steady when the rest of the missile turned. This is important because the system requires ABSOLUTE, not relative bearing.

>>33528250
>Now, if you turn LEFT directly toward the ship
What I meant to say.

>>33528234
You don't need diffeq to understand whats going on. I can't do it (yet), but I can understand what's up with an understanding of integral calculus. On the other hand, algebra is grossly inadequate for the task.

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>>33527767
Overall methodology is the same. I just oversimplified it for anon.

Also AIM-9B seeker

>>33528234
>hardcore differential equations
haahhaha
yeah real hardcore
its ez pz shit that technicians learn

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>>33524383
The IRIS-T is so fucking sexy holy shit

>>33528334
>I can't do it (yet), but...

You understand nothing

>>33527430
Bro do you even loop shaping

>>33524383
With older IR seekers it was a matter of scanning in a pattern and finding where more heat was coming from (which is why IR missiles used to fly towards the sun if launched incorrectly).

To target planes and not flares / balls of nuclear fusion, they would use filters to look for certain IR wavelengths, as well as electronic filters (that area gets complicated).

Most modern IR seekers like the one in the AIM-9X and ASRAAM have IR focal plane arrays, so they just act like cameras, using software to look for certain shapes, azimuth / elevation change rates, etc.

>>33528250
>>33527767
Quality posts

>>33527361
One of three things:

1. The missile starts off with a lock on a target; modern systems will visually show you what it's locked onto, in the past it was a bit more of a guessing game based on missile growl and what you saw in front of you.

2. The missile is launched LOAL style; for missiles like the ASRAAM, the missile is launched with a target vector (direction relative to the starting point); the missile turns in that direction and locks onto the brightest, most plane-like in that direction. An AIM-9X Block II is the best missile out there for LOAL; it has a data link that allows the parent aircraft to continually update the missile with a 3D target coordinate, which avoids issues around parallax and manoeuvring targets in close proximity.

3. It doesn't and the missile goes after a friendly.

>>33529457
>AIM-9X Block II is the best missile out there for LOAL
Best among IR missiles, perhaps.
All active radar-guided missiles lock on quite a long time after launch.

>>33529469
This is a thread specifically about IR missiles, so that was the implication

>>33529478
Ok then.
On a related note, what's your opinion on the Python 5?

>>33529506
Not a bad missile; it's highly agile and it has a higher resolution seeker than the 9X or ASRAAM's, but it's also a bit short ranged. Not sure what its data link situation is though.

OP here, can someone clarify the function of the early missiles rotating mirror setup? I read that portion of the wikipedia article, but it was (like most of wikipedia) articulated poorly.

>>33527361
iirc this is partially why chaff is a thing

>>33529735
not knowledgeable in the field, but I would assume the rotating mirror acts as a seeker for the target and is almost like a gyroscope, wanting to be parallel with the rest of the missile with the target in front of it.

can someone give me some insight to, assuming this is true, why missiles will sometimes lose track of their targets during tight maneuvers? Does the target simply exit the tracking space of the missile?

>>33529381
Spoopy

http://www.mediafire.com/file/nq6i1ja0ds9gqi4/Histoy+of+the+Electro-Optical+Guided+Missiles.pdf

Here, get learned

>>33526528

I came to this thread just to see if this had been posted yet.

>>33529735
The mirror is an intentionally imperfect ball surface which means that when it's spinning it does not look straight ahead but instead the focal point moves in a scanning circle, when the red hot tailpipe happens to be in the scanning cone the IR waves are reflected from the mirror to the detector unit, then the current rotation of the mirror and the point on detector unit where the IR beam hits are used to deduce the angle-off from the missile's axis

I think it read like this in some possibly FOUO manual I had my hands on regarding the AIM-9s

>>33528250
>>33527767
Are missiles alive, in a philosophical sense?

>>33530445
What do they use for thermal mirrors? I've seen that stainless steel works quite well: https://www.youtube.com/watch?v=WVAhLcJOtAo