Autonomous subs use AI to wayfind without GPS | Hacker News Reader

Autonomous subs use AI to wayfind without GPS

spectrum.ieee.org

50 pointsBrajeshwar45 comments

The sub 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 sub 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.

(Couldn’t resist).

Sir Humphrey, you're an expert on autonomous submarines, too. How hadn't I guessed.

Paper: https://ieeexplore.ieee.org/document/10304148

My sense is that the authors' focus was on stabilizing the vehicle in varying conditions (ocean currents), and the training time needed to achieve that, rather than wayfinding. Not sure why the beginning of the article is so oriented towards navigation.

Although underwater vehicles are very much not in my wheelhouse this seems actually more interesting; I wonder what other applications there might be for the learning method they propose.

What a time to be alive. A time where software errors could potentially start international nuclear conflicts.

If you were alive in the 80's, it's not the first time ;-) https://en.m.wikipedia.org/wiki/1983_Soviet_nuclear_false_al...

Also, the 80's movie 'WarGames'

True, but somehow AI makes this worse for me.

> AI doomers are a sci-fi flavored rapture cult, full of vocal crazies spreading overblown fears

> Stochastic parrots and other animals in linear algebra zoo ain't going to end the world

> Proceeds to put black-box SOTA ML models at the core of Mutual Assured Destruction dynamics

What could possibly go wrong.

Somewhat related, see underwater acoustic communication ('water modems'):

* https://en.wikipedia.org/wiki/Underwater_acoustic_communicat...

In 2017, NATO formalized the JANUS standard (STANG 4748):

* https://www.cmre.nato.int/rockstories-blog-display/398-janus...

* https://nso.nato.int/nso/nsdd/main/standards/ap-details/1770...

Related: Royal Navy says quantum navigation test a success https://news.ycombinator.com/item?id=36222625

Instead of gps, submarines can use maps of the gravitational constant for navigation

Is it just me or does this feel like another "we must stuff AI into everything, just because"? Inertial navigation has been around for most of a century, i.e. before GPS even existed, and is basically self-contained.

AI is a contemporary marketing term. Statistical methods that go under that umbrella term has been used for a few hundred years. AI has now become hip, so anyone using any methods that could conceivably be put under that marketing term is now being done.

AI is definitely a big buzzword right now, but in this particular case inertial navigation has a pretty big limitation: cost. Cheaper sensors with better software would be a legitimately compelling alternative to traditional solutions.

Learning that is difficult. It is a skill that needs to be worked on by learning maths, then control, dynamics. Instead, learn to use an AI framework and you can solve the problem with orders of magnitude more computing.

Not advocating one way or another, just that that's probably the thinking. Also, it's in vogue.

Its far easier to stuff 8 H100s in a submarine than to add another headcount.

Every person in a submarine consumes valuable space/food/oxygen. Cooling and electricity on the other hand are easy to solve, when you have a nuclear reactor and a dead cold ocean right outside.

So if possible, AI will be used to perform these duties.

Inertial navigation is a sealed box and doesn't require more headcount than the H100s.

In the outer space, yes; you can compute orbits for millennia to come. In the ocean, with its currents, it's way less easy.

I don't think you understand, inertial navigation is not computing (as in predicting) anything. It is a bunch of sensors to measure where you are.

Using AI to predict where you might be based on crappy cheap sensor data and ocean simulations is never going to be precise enough. AI can't pull signal out of noise and uncertainty.

> Using AI to predict where you might be based on crappy cheap sensor data and ocean simulations is never going to be precise enough. AI can't pull signal out of noise and uncertainty.

Yeah, but people with monies see this as "AI can help replace expensive milspec hardware with cheap COTS garbage plus some software magic pixie dust, for approximately the same effect [during peace time, in harbor]".

And there will always be low tech, self contained back up systems in place. And I was not aware that current military subs had problems with navigation that require AI to solve, or issues with life support.

GPU clusters already exist on them.

it's interesting to study a balance neural network by evolving a few and going "so how would this AI withstand choppy seas"

if it checks up with the map of how our brains learn to keep us upright, then we learn other side effects of how brains grow and learn

if it doesn't... then it's even more interesting because there's another confounding variable.

I reckon inertial navigation is dead.

Assume it's down to subs not being very common in civilian use that prevents someone deploying a gps-like triangulation system that's sonar based?

If it were even possible.

Submarines can receive GPS signals by towing an antenna that floats on the surface

Leaving any mark on or near the surface limits stealth, right? Better to eliminate that need of possible.

Does this work well in practice? Seems there could be a non-negligible opportunity for fouling of the tow line/gps unit

https://secwww.jhuapl.edu/techdigest/content/techdigest/pdf/... example

I was under the impression that subs mostly use dead reckoning when submerged.

Good inertial navigation units are really good. I had a professor who liked to tell the story of having one on the top floor of the engineering building and if you left it on all day you could watch your altitude go up and down as the building warmed up with the sun and cooled down at night.

I think any unit that couldn't do that would be useless as it wouldn't have the accuracy required - it would drift within a day otherwise.

More interesting would be to understand how much its position drifts over a period of days or weeks.

Some level of drift is acceptable depending on the mission. Aircraft and missiles only fly for a few hours at most, and may be able to get a satellite or stellar fix at least intermittently.

dead reckoning has to account for currents etc, which is something you could use AI to improve as per the paper. It's actually a _good_ application of AI?

Subs use very expensive and very impressive inertial guidance systems, which can go up-to a week without correction. But that doesn't scale down to the modern world of small autonomous systems.

The currents would accelerate the dead reckoning unit just like any other force, including from the impellers.

Not arguing that small autonomous systems could use something smaller and cheaper.

The dead reckoning itself doesn't detect the ocean currents; these are separate estimates that need to be integrated to determine actual position https://en.wikipedia.org/wiki/Submarine_navigation#Deep_wate...

Huh, I don't understand why. :-D Someone please explain. If I tugged the sub, wouldn't the IMU detect that? Why is a current doing the tugging any different.

now I'm guessing, but perhaps it's like if you walk up the aisle of a moving train, how fast are you travelling? And how fast does it feel like you're travelling?

Sure, I would get confused by that too, but I thought the point of the IMU is that it has its own frame of reference. Elsewhere in these comments was someone mentioning an IMU which could detect a building growing in size when warmer. The IMU doesn't "know" there's water outside or how the water is moving. It knows how much force it's been pushed around by.

Aha! IMU <> "dead reckoning"? In the wikipedia article they are listed separately. Dead reckoning is meaning tracking things like the revolutions of a propeller and a compass to compute position, whereas an IMU is three accelerometers, three gyros and three magnetometers? https://en.wikipedia.org/wiki/Inertial_measurement_unit

Haha oops. :-)

many INS packages also include a DVL (Doppler velocity log) which measures speed over ground if you’re in range of the bottom.

This went really well in Mission Impossible: Dead Reckoning.

Which part of that movie? Thanks.

The opening scene, although they don't go into much detail about how the submarine works.

I have a UUV that cleans my pool.

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