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Author Topic: Missiles, Bombs and Rockets, Guided/Unguided Munitions  (Read 25762 times)

Uriah

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Missiles, Bombs and Rockets, Guided/Unguided Munitions
« on: December 25, 2014, 06:40:50 pm »

In collaboration with a number of others, I am developing guided and unguided munitions for aircraft and ground vehicles. The seeker script will simulate a sensor to guide the munition, and switch between target-lock and target-null modes. GPS, IR and radar sensors we be implemented, with GPS being the first and easiest to script. IR (infrared) will calculate the thermal contrast between the target and its background, (look-up table), and radar will calculate radar cross-section at a given target angle (also using a look-up table).

It is planned there will be one of each of the following:

Air-to-Air Missile
Air-to-Ground Missile
Surface-to-Air Missile
Ground-to-Ground Missile
Precision Guided Bomb
Unguided Bomb
Unguided Rocket

I am not going to say much besides that for now.

Regards,
Uriah

IF YOU HAVE A 3D MODEL OF A BOMB, MISSILE, OR ROCKET YOU CAN:

Send me the 3D model in 3ds, max, fbx, obj, iges or other 3D Studio importable format. If you would like you can help create the JSBSim Flight Dynamic Model (FDM), and incorporate it into your project, aircraft, ground vehicle, ship, submarine or other launch platform.

I need the raw 3D model so I can set it up correctly for exporting to FBX, labeling BONES and materials, aligning the pivots for moving parts, and detailed animation if necessary.

If have a detailed 3d model that is not textured, myself or someone else can produce the texture and materials.


Here is the AGM-65D IIR:





« Last Edit: January 04, 2015, 08:08:51 am by Uriah509 »
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ZeosPantera

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #1 on: December 26, 2014, 02:23:11 am »

The seeker script will simulate a sensor to guide the munition, and switch between target-lock and target-null modes. GPS, IR and radar sensors we be implemented, with GPS being the first and easiest to script. IR (infrared) will calculate the thermal contrast between the target and its background, (look-up table), and radar will calculate radar cross-section at a given target angle (also using a look-up table).

No series of words put in a particular order has made me this hot..
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2eyed

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #2 on: December 26, 2014, 05:13:41 am »

Now there is a world, let the bombing begin. ;D :-[
Mankind = war?
After all it's Christmas.
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PytonPago

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #3 on: December 26, 2014, 07:04:27 am »


After all it's Christmas.


 Christmas is THE best time for invasions. ... no one checks they presents and Santas. He knows best, just ask him :



Doe, cant tell why thy aliens have that GB complex ... cant start without trying to knock up BigBang.   ;D  ;D  ;D

P.S.: Hope you didnt open the ones still ticking ... better to not get those clocks, right ? Or am i the only one getting tons of such packages ? :D
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We are still undeveloped as long as we don´t realize, that all our science is still descriptive, and than beyond that description lies a whole new world we just haven´t even started to fully understand.

Uriah

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #4 on: December 27, 2014, 11:12:58 pm »

 :)

Working on the basic guidance algorithm, a lot of complicated equations in Excel right now. Optimal control algorithms for guidance are not available publicly that I can find, so I will have to synthesize moving target position prediction for the guidance in the initial boost stage and sustain boost stage, after which the trajectory is more or less set. There are complications with OT, but regardless this is more of a math problem and determining how to implement it with the existing JSBSim Guidance/Control framework.

Regards,
Uriah




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HiFlyer

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #5 on: December 28, 2014, 12:49:45 am »

This is absolutely amazing, and I hope its progressing apace with other advances by the developers, such as a clickable environment for various vehicle types
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PytonPago

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #6 on: December 28, 2014, 02:20:53 am »

... clickable environment for various vehicle types

Yes, that will be a great thing once getting in !
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Fighter117

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #7 on: December 28, 2014, 03:31:41 am »

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Uriah

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #8 on: January 03, 2015, 12:53:17 am »

I am still wrestling with the JSBSim Guidance Control... it is a son of a %^$#($@!!!

So far I am able to make the seeker/sensor track a moving target, calculating the target distance and angular position of the target Line Of Sight relative to the missile’s longitudinal axis.

I set the AGM-65D (IIR Maverick) and AGM-65E (LASER Maverick) using the same object package, with different albedo, normal and roughness maps, and different script file and FDM. When the IIR Maverick is spawned, the LASER_seeker/sensor meshes are hidden, and vise-versa.

It took my some time to get the hang of using roughness maps, but the result really makes the paint markings pop-out from the base-coat. :D

-Uriah















AGM-65 Blank Object:

« Last Edit: January 03, 2015, 12:56:02 am by Uriah509 »
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PytonPago

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #9 on: January 03, 2015, 03:59:08 am »

So youre trying to say if its longitudinal axis (that is head-to engine) is laying on the imaginary line between it and the target and correct the angle to fit it if not ?

 ... nice way, adding a special heat-source signature on planes/vehicles and re-script it to track these would be nice for enhancement playing as the aerial target maneuver angle (witch can hide or delude the heat signature at certain angles) and flares. - (for the IIR)
Something similar for the laser guided, doe targeting an placed point by the guidance system of the rockets launch system.

Know there are some rockets guided by a back-facing IR sensor - mostly tank and armor based AT rockets, witch actually dont see the IR signature on the target, but just "look" behind themselves to stay in the lasers beam. Would be an interesting thing to try that too ...
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We are still undeveloped as long as we don´t realize, that all our science is still descriptive, and than beyond that description lies a whole new world we just haven´t even started to fully understand.

Uriah

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #10 on: January 03, 2015, 04:35:15 am »

Quote
So youre trying to say if its longitudinal axis (that is head-to engine) is laying on the imaginary line between it and the target and correct the angle to fit it if not ?

Not quite, it is a bit more complex. I am measuring the instantaneous angular velocity of the target each frame update call, and calculating its angular acceleration/deceleration, relative to the missile's Y axis. If the missile pointed at where the target is NOW, it would never hit the target. The boost phase of an AGM-65 Maverick is around 0.5 seconds, and the sustain boost phase is around 3.5 seconds, so the missile reaches its maximum velocity within four seconds and then decelerates during what is called the terminal flight phase on its way to the target. It must calculate the targets angular trajectory, relative to the missile seeker, and steer the missile on a collision course with the target's FUTURE position.

For NON-moving targets, what you said would be true, and the script is far less complex.

For simulating infrared target signatures there are a number of ways to accomplish it in terms of developing a simple algorithm. I need to do more research about IR countermeasures, but I believe the missile seeker logic will be to track the thermal signature with the greatest magnitude. In sim, the a thermal signature is just a point, with a variable assigned to the point by looking up the value in an X, Y angle table. The script would calculate the X angle, and Y angle for each IR signature, and request the IR signature values of all the points within its current Field Of View, and calculate for scattering and attenuation of the signal given distance, altitude, etc... The Seeker script would then track the IR point with the highest magnitude signature.

Signal to Noise Ratio (SNR) is especially important, (aka. thermal or infrared contrast, or target/background contrast ratio) but I cannot think of a way to implement such a functionality in a script.

The LASER Maverick tracks an active IR source, and there is a lot more to take into account, such as emmissivity/reflectance of the target, and attenuation of the laser source round-trip.

Everything will be defined under 'Sensor', so the same 'Seeker' script could use many different sensor scripts, both forward and rear facing.

Pyton, I believe those are called Beam Riding seekers, where an electromagnetic (RF/IR) beam is projected at the target and the munition attempts to stay at the center of the beam. Yes that could be done too, but there would be differences to the Guidance/Control System.

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PytonPago

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #11 on: January 03, 2015, 01:35:22 pm »


Not quite, it is a bit more complex. I am measuring the instantaneous angular velocity of the target each frame update call, and calculating its angular acceleration/deceleration, relative to the missile's Y axis. If the missile pointed at where the target is NOW, it would never hit the target. The boost phase of an AGM-65 Maverick is around 0.5 seconds, and the sustain boost phase is around 3.5 seconds, so the missile reaches its maximum velocity within four seconds and then decelerates during what is called the terminal flight phase on its way to the target. It must calculate the targets angular trajectory, relative to the missile seeker, and steer the missile on a collision course with the target's FUTURE position.


Had that in mind before (for the IIR), but i meant the laser one - the simple approach ...
« Last Edit: January 03, 2015, 01:40:33 pm by PytonPago »
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ZeosPantera

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #12 on: January 03, 2015, 02:30:00 pm »

The reflections on the front of those guided bombs. Is that generated in-engine because I thought it was a generic reflection map until the dev's implemented something else.
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PytonPago

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #13 on: January 03, 2015, 03:54:40 pm »

The reflections on the front of those guided bombs. Is that generated in-engine because I thought it was a generic reflection map until the dev's implemented something else.

It seems like what mirrors do - spawn-state environment map.
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We are still undeveloped as long as we don´t realize, that all our science is still descriptive, and than beyond that description lies a whole new world we just haven´t even started to fully understand.

Uriah

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Re: Missiles, Bombs and Rockets, Guided/Unguided Munitions
« Reply #14 on: January 03, 2015, 05:11:16 pm »

Yep, Outerra reflections are awesome. Here I use two meshes, with two materials, in order to get the look I wanted. The bottom layer mesh is slightly smaller than the top one.




The IIR dome uses an opaque/rough orange layer underneath the glass layer with the reflection.




On the LASER dome I put the glass layer beneath an alpha masked layer with an opacity map to make the jagged coating ring around the edge.




Shall I say... coming soon. :)

« Last Edit: January 04, 2015, 12:07:47 am by Uriah509 »
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