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back to article DARPA looks for a guided bullet with DEAD reckoning navigation

Madcap Pentagon tech shop DARPA is looking again at the Global Positioning System (GPS, which makes almost all the world's satnav systems work) in a bid to reinvent the tech which used to be cutting edge military gear but these days is tracking dogs and finding golf balls. DARPA's director Arati Prabhakar has announced that GPS …

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Inertial? no way

You can't a fully inertial system.

The problem is the inicial shoock of the shot will provide way more Gs than current sensors can detect/withstand: so you don't know your speed.

Therefore, you need a laser guidance system so you know where you are. Maybe an hybrid system could be made, with a reduced powder bullet and gyrojet hybrid, laser riding at first and then inertial navigation.

I could see it inside a .50 BMG.. but a 5.56? no way! Maybe an automatic shotgun would be a better option: high caliber, low pressure, slow bullet (but as it is guided, no problem with that).

Still, it would be WAY better to have that for a grenade launcher.

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FAIL

Re: Inertial? no way

You can use MEMS inertial sensors, which can withstand huge accelerations (>20,000 g) - I used to work on them.

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Anonymous Coward

Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

No, it would not.

Quaker here, and quite angry. The US has flooded its own country, South America, and the Middle East with cheap weapons and the results are all too obvious.

The relentless drive of the US to make weapons smaller and cheaper destabilises the whole world, and it needs to stop. Now.

Far more people in history have been killed with small, cheap weapons that with large, complex ones. If you must develop these things, make it so only governments can afford them.

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Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

"Far more people in history have been killed with small, cheap weapons that with large, complex ones. If you must develop these things, make it so only governments can afford them."

You mean like AK-47s and RPG-7s?

Don't lay the blame at cheap weapons solely on America's doorstep when plenty of other people are selling even cheaper ones. Most of the weapons being used in worldwide conflicts today have never been near CONUS.

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Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

You have rather missed ribosome's point, it appears.

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Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

> If you must develop these things, make it so only governments can afford them.

Nice idea in theory, but the reality of modern technology is that anything a government can afford today will probably be feasible in a well-equipped garage in 10 years time. At least by having the big guns (pun intended) research & make these things there's some chance that they'll be able to keep such measures (and countermeasures) ahead of the amateurs.

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Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

@ribosome

Really? I guess the ENTIRE COUNTRY also loads the ammo and fires it at childern too correct? Get over yourself. Bad people do bad things. They will use anything. Guns, knives, bombs, cars, airliners, you name it. But it is much easier to blame one country for all of the world's problems right? Sod off.

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Only governments? Like Syria perhaps? Or Iraq or Afghanistan. Or maybe you mean only large countries like China or Russia, as they never shot anyone they couldn't drive a tank over.

I do share some of your thoughts, if we shifted the energies we put into creating weapons into drugs research, space exploration, hell anything! We would probably have a nicer world, at least for as long as it took for one nutjob to realise anybody with an ak, some gardening gloves and a decent warface could rule the world. It's a nice thought, but unfortunately probably impractical.

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Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

"Far more people in history have been killed with small, cheap weapons that with large, complex ones. If you must develop these things, make it so only governments can afford them."

If you "must develop these things"? Wow. And why would you want to let 'governments' have a monopoly on weapons? Do you think that it will make our lives better and lead to fewer people getting killed?

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@ribosome

"Quaker here, and quite angry. The US has flooded its own country, South America, and the Middle East with cheap weapons and the results are all too obvious."

Well, ignorant moralizing is actually the essence of Quakerism, is it not? (It's actually a rhetorical question; I am just curious to see if you will admit it or not.)

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Anonymous Coward

Re: Inertial? no way -"Still, it would be WAY better to have that for a grenade launcher."

yea, it SUCKS that we allow people who are not powerful and wealthy the means to defend themselves against the rich. Why with weapons being only the providence of the rich and powerful, we will have peace-peace because everyone is crushed under the heel of whomever has the most cash. don't want uppity peasants having power-parity now do we?

Suppression of conflict through overwhelming force is not a "peace" I want any part of.

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JLV
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@ Angry Quaker

Hmmm, not sure if I agree or disagree.

First, fully with you that there are way too many cheap guns being used to kill & terrorize years after the wars are over.

But the US military industrial complex is hardly known for bargain weaponry, quite the opposite. And many of the small arms you rightly criticize are more the AK-47s, not least because they require less maintenance.

On the other hand the US dominates weapon exports (not for lack of other countries trying to peddle their wares, mind you).

A worthy goal for DARPA? :

How about developing weapons with a built-in life "clock"? For example, nano-coat a rifle barrel so that it works fine, for say 5 years? Then it gradually degrades and stop working. Or Stinger equivalents whose electronics die after that time as well? (the US had to run an expensive program recovering those from Afghanistan in the 90s). Ditto for gradually degrading explosives that would become inert.

Third world countries facing a military emergency could receive aid, but the weapons would not survive the war by much. This could be used to arm the least worse faction in Congo, for example.

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Anonymous Coward

Re: @ Angry Quaker

That would actually be a cool idea. It would also give some indication as to WHEN someone (country) plans to use the weapons (less than 5 years, right?). Thus allowing us to all move house or whatever.

Unfortunately, the market would probably just get flooded with cheap "non-self-destruct" weapons and people would then merrily continue killing each other, probably with a combination of smart and stupid weapons.

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Pint

Re: @ Angry Quaker

Plenty of munitions have 'use by' dates.

Why do you think the US tosses so many Tomahawks around after a 'dry' war-free period?

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"DARPA looks for a guided bullet with DEAD reckoning navigation"

You know, I could really use some of those....

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Headmaster

Science Fail

navigation is just a matter of knowing one's __VELOCITY__ and duration of travel - with suitable accuracy of course.

****

FTFY

navigation with speed and time is useless without direction but velocity contains a direction compnent.

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Happy

Re: Science Fail

Have you been listening to 'They Might Be Giants'? You've almost directly quoted from their kids science album.

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Anonymous Coward

'DARPA's research rarely produces tangible results'

Bit unfair, no?

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Re: DARPA's research rarely produces tangible results

Yeah, like that ARPANet. Whatever happened to that pie in the sky project?

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Not fair! I distinctly remember they managed to build some portable air conditioned holding tanks inside small hangers for trained navy dolphins so they could survive in the desert and be deployed in rivers and the gulf by Iraq.

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"Jackal" eat your heart out.

If they develop these it's only a matter of time before the 'bad' guys get hold of some (given that it's the USA they'll probably have a constitutional right to buy them on Amazon) - and that means there's not a politician in the world will be safe. Has Obama authorised this project?

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FAIL

Re: "Jackal" eat your heart out.

"and that means there's not a politician in the world will be safe. Has Obama authorised this project?"

That's a stupid-ass comment.

Sniper rifles can already hit people over a Km away and have been able to do so for years, and yet politicians aren't being gunned down by them in droves. What makes you think that increasing that range to maybe 3km will make a lick of difference.

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Re: "Jackal" eat your heart out.

"and that means there's not a politician in the world will be safe"

I don't see a problem here.

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Anonymous Coward

Re: "Sniper rifles can already

Yep...

I work near a law court and see the met posturing outside with their sub machine guns, body armour and poor firearms discipline from time to time, and it has occured to me that two WW One era snipers suitably located could take the lot out without even drawing breath, let alone what could be done with modern kit.

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Re: "Jackal" eat your heart out.

Maybe this: The area to be guarded grows in proportion to the radius squared and "they" will run out of either donuts or guards rather quickly? The difference by going from a1 km to a 3 km protection zone is nine times more personnel for the same job!

OTOH - Mortars already cover 3 km and they have the advantage that the attacker could be well on his way before the first round lands.

Maybe only crazy people care about politicians after all - and being crazy, they cannot organize anything?

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@fajensen: Re: "Jackal" eat your heart out.

Well, Marshall Applewhite was certifiable and he organized Heaven's Gate. That was a pretty effective organization from an, uh, organizational point of view...

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Re: "Jackal" eat your heart out.

"Sniper rifles can already hit people over a Km away"

AND

"increasing that range to maybe 3km"

Well, given that the record for sniper hits is documented at 2815m, increasing the range to 3km doesn't sound like much of an achievement.

It's also worth noting that the article tries to make a distinction between .50 cal weapons and sniper rifles. All but one of the sniper hits beyond 2km listed in http://en.wikipedia.org/wiki/Longest_recorded_sniper_kills were made with .50 cal weapons, either specialist sniping weapons or in one case an M2 machine gun.

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Headmaster

Re: "Jackal" eat your heart out.

"Sniper rifles can already hit people over a Km away and have been able to do so for years, and yet politicians aren't being gunned down by them in droves. What makes you think that increasing that range to maybe 3km will make a lick of difference."

Fair point, but the ability to hit what you want to hit at that range is quite a specialist skill (and requires very well known and constrained atmospheric conditions). Give a sniper rifle to Joe Bloggs and he's be lucky to hit a multistory carpark at that range, let alone a person in it.

But yeah, I agree with you, preventing DARPA from coming up with such a thing doesn't keep Pandora's box shut.

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Stop

Re: "Jackal" eat your heart out.

"Well, given that the record for sniper hits is documented at 2815m, increasing the range to 3km doesn't sound like much of an achievement."

Smug stat; moot point.

It was a highly trained sniper, using a large AMR, and wasn't even a first-round kill. That's of very little comparative value. Whereas a good shooter with a firearm of much more reasonable size and calibre can wax someone 1km away without much fuss. Using extreme examples isn't really of much use to anyone.

I'm pretty sure .50 HMG gunners in SF roles have mowed plenty of people at more than 3km anyway.

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Reference position?

Having actually implemented a simple dead-reckoning algorithm to track vehicle movement between GPS fixes (when passing through a tunnel, for instance), I wonder how they get an accurate position in the first place?

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Re: Reference position?

Simple:

They measure the angle between a number of celestial bodies and the horizon and determine the offset angle between their position and the ground point of the chosen body by referencing almanac data for the chosen body against an accurate time reference then finding the intersection of the offset angles. Oh yeah, probably the easiest way to get an accurate time reference these days is from the GPS constellation, but hey ho.

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Re: Reference position?

> I wonder how they get an accurate position in the first place?

They don't need one, all they need is an accurate relative position for the target.

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Re: Reference position?

In an ideal shot, there would be only the (predictable) acceleration (negative of course) from the air friction. Any other acceleration vectors (including a difference to the predicted acceleration) are due to unexpected wind occurence.

The control algorithm/circuit in the bullet will record these acceleation vectors over time, will integrate these over time and then attempt to perform counter-accelerations (via fins or thrust vector nozzles).

As Mr Newton put it:

v(t)= INTEGRAL(a(t)*dt)

s(t)=INTEGRAL(v(t)*dt)

So if you have an ultra-precise acceleration sensor (very difficult)and an ultra-precise integrator (easier, can be done with a digital thing called computer), you know very well your s(t). In all directions of space, of course. You also need a very precise clock, but that we can do for a long time with quartz clocks (at least for the bullets).

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Early Knife Missile ?

So this is how the Cultures knife missiles got started?

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Anonymous Coward

How is navigation performed?

Once the bullet knows it has to change course, how does it actually do it? Flaps? Onboard gaz jet?

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Paris Hilton

Re: How is navigation performed?

Pivoting Inflight Streamlined Steering flaps.

I wish I could think of a suitable acronym for that.

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kit

Re: How is navigation performed?

It all comes down to the nano-nisation of microelectronics, Imaging if you can integrate a tiny camera together with image processing processor all inside the bullet. It is not impossible to have a guided bullet does what you want to shoot at.

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Re: How is navigation performed?

And you don't need a camera in the bullet IF the accelerometer is sufficiently precise. All you will do is to load the desired trajectory into the bullet and then the bullet control system will try to control course according to that intended trajectory. That's why they say "dead" reckoning. Because there are no "live eyes" looking out of the window.

I also assume the first application will be smart bombs cued by FLIRs. Maybe the Great Colonel actually did some GPS jamming we are not aware of. Or they want to send the gracious eternal leader of norkia a message and he is already doing massive GPS jamming.

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Still a Bullet?

A bullet is an unguided non powered projectile. What will this thing actually be?

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Headmaster

Re: Still a Bullet?

So long as it misses me I won't care what its defined as - and if it hits me I'll care even less...

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Ru
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Re: Still a Bullet?

and if it hits me I'll care even less...

You are of course assuming that the intent is always to kill.

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Headmaster

Deceased Navigation?

What is this Dead Reckoning of which you speak? Do zombies use it to find Brainz?

The correct term is DED reckoning - short for deduced reckoning, in that your current position is deduced from a previously known position, using knowledge of your course, speed, wind/tide drift etc.

Of course if you get it wrong you may end up dead.

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Anonymous Coward

Re: Deceased Navigation?

Maybe you are right about acronyms, but it seems to work via integrating first acceleration then speed to yield position.

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Re: Deceased Navigation?

It's been called "dead reckoning" for as long as I can remember and quite some time before that. I recall reading about pilots using it in VFR, about offsetting the nose of the aircraft from the destination to compensate for crosswinds, in a book about aircraft I had as a kid back in the 70s. And Melville also uses the term in Moby Dick, when he describes in some detail the "log and line" method of navigating: You heave a log tied to a line overboard and count how long the ship takes to sail past it. Melville's protagonist even points out how this method is unreliable and inaccurate compared to the quadrant, which Ahab had destroyed during one of his psychotic episodes the day before.

So "dead reckoning" goes back close to a couple of centuries at least.

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Too much in too small a space

The only reason that bullets fly so far is because they are *dense* *as* *lead*. If they aren't that dense, they don't fly as far. Even with something as large as a .50-cal bullet (and I mean the /bullet/, not the entire cartridge), there isn't enough space for both electronics, navigation control, and *mass*.

Another critical point is that the bullet will be rotating in flight, and doing so very quickly. Is the navigational control going to be able to overcome wind drift? If it can't even do that, then it's useless.

Basically, this is a money-wasting project. Nothing new. A bullet has to be dense and travel extremely fast. Anything else defeats the purpose of it being a bullet.

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Re: Too much in too small a space

No problem: just use depleted livermorium.

(Just make sure you can get that round fired quickly!)

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With Some Cold-U238 Teutonic Rationality

..I would counter your argument saying that you can compensate quite a bit of "hollowness" by using U238 instead of lead. So the tip of the projectile would be extremely heavy to allow for the bottom to perfom some navigation/stabilization wizardry.

Quite interesting engineering challenge, even though it seems there are already more than enough ways to kill people at a distance.

I also assume some sort of lightweight, mobile radar or laser tracking a sniper bullet, followed by a rapid second shot which corrects for the curent wind situation would probably be as effective. Or even more, as you don't need the hollow space for the navigation/stabilization stuff.

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FAIL

Re: Too much in too small a space

Of course, you know more about the entire project sat in your armchair than all the people with Phds working on it.

Bullets fly so fast because they are dense and fast. They travel much less further than they could because they are fired at a shallow angle. Add a guidance system and you can loft them at a more optimum trajectory like a arrow, overcoming any deficit due to lower mass. Put in some dense material such as tungsten or DU and you can partially overcome any shortfall due to not using lead, anyway.

In short, I'm pretty sure the well-paid people have thought a bit more about it than even you, so I don't see the point of rubbishing a project that we know barely anything about.

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Anonymous Coward

G forces at moment of firing

G forces at the moment of firing are not a problem. In WW2, proximity fused anti-aircraft rounds were used extensively in the Pacific war (and are credited with making Kamikaze attacks significantly less effective). They used vacuum tubes, not solid state electronics, which hadn't been invented yet. True, they were specialized vacuum tubes, but they could obviously stand the shock of being blasted out of a anti-aircraft gun and still work.

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