Vaccum-chamber quantum sensor device could allow GPS-free navigation

https://breakingdefense.com/2021/11/sandias-atomic-avocado-could-allow-gps-free-pnt/

by tomohawk • 5 years ago

129 83 5 years ago

TLDR; Sandia researches dead reckoning with a new kind of atomic accelerometer and gyroscope.

It has nothing to do with avocados, aside from someone comparing the device’s size to that of an avocado, and that was probably the only thing the journalist understood so they went with it…

FeepingCreature• 5 years ago

Yeah this article is very bad.

gsliepen• 5 years ago

Indeed. Also, the old system apparently "needs thousands of volts of electricity," which is too much for airplanes, despite them heating food with microwave ovens which typically use > 10 kV to drive the klystrons that generate the microwaves.

pixl97• 5 years ago

I'm guessing they turn off the microwave when things go bad, like engines going offline and reducing total power generation to the aircraft.

tialaramex• 5 years ago

To be fair the "thousands of volts of electricity" nonsense is in their own press release not just this fluffy article.

It's really hard to get the people writing for a lay audience to actually understand the difference between "Simpler for lay people to understand" and "Simply wrong". This is sort-of fine if you're making a Hollywood movie, but it makes serious research look pretty stupid. Unfortunately the rare person who understands and knows how to communicate this stuff to lay people is probably more valuable as a lecturer or in some management role than writing press releases :/

dboreham• 5 years ago

Perhaps it is green.

tartoran• 5 years ago

I really appreciate the TLDR; Saved me and others quite a bit of time

analog31• 5 years ago

Looks more like the size of an oscillation overthruster.

yetanother-1• 5 years ago

Yes, but how will it determine its position without a reference, I read the article and missed that concept.

saboot2• 5 years ago

I'm also confused by this, does it get set a reference point once? If so what is the accuracy degradation, is it fixed over time or acceleration?

If it's updated periodically what does that system look like? Is the advantage that it can manage on its own "offline" for a usable period, unlike GPS which needs an active connection?

mynegation• 5 years ago

All great questions, but I suspect the answers are classified.

saboot2• 5 years ago

Here's the press release from Sandia https://www.sandia.gov/labnews/2021/10/22/this-device-could-...

And the published paper it refers to https://avs.scitation.org/doi/10.1116/5.0053885

And I agree that the answers to my questions are probably not public, this is likely going to be very useful for things that go boom, in addition to a lot of other civilian applications.

throwawaylinux• 5 years ago

The reference is your previous position. This is known as dead reckoning.

Snoozus• 5 years ago

Just like dead reckoning works today, you start from a known point at known attitude and integrate up accelerations and rotations to keep an up to date position. Whenever you can get a GPS signal you use that to reduce the drift. Cheap systems can do this for seconds, 10k$ buys you 15minutes (MEMS), 100k an hour (laser gyro), everything above is under export restrictions and NDAs so noone will tell you what the state of the art is.

Looks like with these frozen gasses one can build even better sensors, which will make no difference for civilian use because it will be even more expensive than existing systems and also because we wouldn't be allowed to use it.

jonplackett• 5 years ago

The whole premise that this might be something in everyday use one day seems completely flawed. Even at the 1cm cube of physics it’s huge compared to GPS and it uses incredibly expensive materials.

If you’re a nuclear submarine or stealth bomber it makes loads of sense. For anything else I don’t really get the point.

pdonis• 5 years ago

how will it determine its position without a reference

It won't. It needs a starting position from an external source, and without periodic updates from some external source, errors will build up in this system just as with any inertial navigation system. As I understand it, this system is just supposed to build up errors much more slowly than existing inertial navigation systems, so it can go longer between updates from an external source before its error becomes too large to be acceptable.

errcorrectcode3• 5 years ago

How is this an improvement over other INS like LRG?

INS mechanisms suffer from the same problem: that they only detect linear or rotational acceleration. To reach position, double integration must be performed, which rapidly accumulates error (drift) because velocity and position both have to be maintained to calculate the next position.

Disclaimer: Trimble Nav alum

snerbles• 5 years ago

While I heard that the effect of double integration is bad, attempting it as a student with consumer MEMS devices was quite dramatic. Really underscores the importance of Kalman filters and updates from sensors with fewer derivatives.

bitwize• 5 years ago

You mean like... GPS?

I used to work on AUVs with inertial navigation, and a Kalman filter accepting input from GPS at the surface and a DVL or similar underwater, as well as the inertial unit, was pretty much standard equipment. The device in the article has to have miraculously low error in order to eliminate the need for GPS.

namibj• 5 years ago

No, you can measure absolute rotation speed. Yes, via a good ring laser gyro. You just can't measure absolute linear speed.

rjeli• 5 years ago

even worse, your (single) integrated gyro estimate must then be fed back into your double integrated accel filter to subtract gravity and further compound errors :)

errcorrectcode3• 5 years ago

Relativistic effects suck. GPS has to consider it when determining a fix too.

mikewarot• 5 years ago

The 10kv power supply for an ion pump could be quite small, as the load current is proportional to leakage. The real innovation seems to be offering a small package without the voltage induced by the ion pump possibly effective the rest of the environment.

The actual paper itself would make it clear what the real advance is, but it's paywalled. 8(

fabiotrezzi• 5 years ago

Am I wrong or this is exactly the project the Sheldon and the rest of the team were working on in Big Bang Theory ?

oatmeal_croc• 5 years ago

This is exactly what I was thinking.

dtgriscom2• 5 years ago

Gee: "titanium metal walls"! "Sapphire windows"!

(Not exactly aimed at the technically proficient...)

dang• 5 years ago

Url changed from https://asiatimes.com/2021/11/atomic-avocado-could-change-th..., which seems to be copying from other sources and mentioning them, but not linking to them. That's a shoddy practice and from a quick look at other submissions like they do it a lot, so I've banned the site.

If anyone knows of a better article on this, we can change the URL again.

avsteele3• 5 years ago

The innovation here appear to be the chamber. (caveat: I still need to read the paper). A few thoughts follow.

They are going for a UHV***, probably <1e-10 mbar, but want to do it with a passive pumping design. In an ordinary chamber to get there you'd do a pump down, then bake it to remove the water. Then use an ion pump plus occasional firing of a titanium sublimation pump to remove the hydrogen that leaks in (ion pumps don't work so well for hydrogen at low pressures). They have some expensive chamber that doesn't suffer from these leaks.

Still a lot of other work to do though. I see a table full of optics to make the MOT*. Also see a pair of anti-Helmholtz coils for the magnetic field. They could maybe replace those coils (which probably drive a few amps) with permanent magnets (assuming they don't need to switch the fields on and off which I imagine they don't because it can't imagine a pulsed design that wouldn't risk missing data)

Passive getters work for a good long time with low leak rates. These you can just buy**. To be honest I'm not sure why you need such a fancy chamber. I'd guess a good NEG pump, a small chamber, and good seals would make you fine for a long time, but I'd need to do the math to be sure.

*https://en.wikipedia.org/wiki/Magneto-optical_trap

**https://www.saesgetters.com/products-functions/products/neg-...

***https://en.wikipedia.org/wiki/Ultra-high_vacuum

chana_masala• 5 years ago

HackerNews amazes me with how for nearly any topic there will be deep expertise in the thread. Thank you for sharing

JohnJamesRambo• 5 years ago

But then it also usually impresses me with how people think companies haven’t thought of and tried the things they thought of in reading the article and thinking about it for a few minutes.

brabel• 5 years ago

The OP seems to know something, but I wouldn't go as far as taking the comment above as coming from an "expert"... the fact they feel confident to make recommendations about improvements on the chamber without even reading the paper actually tells me they are just armchair expert.

kragen2• 5 years ago

Does passive pumping mean a chamber full of baked zeolite or something that's then chilled to adsorb all the gas? I guess I should read the paper too, but I don't have a copy.

Fronzie• 5 years ago

Or even without the chilling. CRT televisions had zeolite as vacuum pump as well. They kept vacuum for up to decades.

nuccy2• 5 years ago

Quantum sensors for PNT use atomic accelerometers or gyroscopes

There is one fundamental problem with using any sensors for global positioning: a stationary frame of reference is indistinguishable from the one moving with a constant speed on a straight (actually geodesic [2]) line (inertial frame of reference, general principle of relativity [1]). So accelerometers and gyros indeed can give you accurate orientation and acceleration/deceleration data, but they will inevitably accumulate uncertainty for long eventless movements, so use of GPS will be needed to occasionally calibrate the true position. The obvious options is to augment this data with readings of wheels rotational, airspeed sensors, radars, etc, then such systems may last even longer without cross-calibration with GPS.

1. https://en.m.wikipedia.org/wiki/Principle_of_relativity

2. https://en.m.wikipedia.org/wiki/Geodesics_in_general_relativ...

dtgriscom2• 5 years ago

they will inevitably accumulate uncertainty for long eventless movements

Actually, they constantly accumulate uncertainty; no change in motion required.

horstbort• 5 years ago

Permanent magnets are typically a no-go, because these sensors employ matter-wave interferometry, i.e. interference between atoms. Those unfortunately do not only react to gravity, but also to magnet fields, so these need to be suppressed as far as possible, especially gradients. And yes, this will absolutely be a pulsed design. I think, the breakthrough here is that they maintain a decent vacuum even without NEGs, which you can of course buy off the shelf, but they still tend to be quite bulky. Also, they state a vacuum of about 10^{-7} torr. Far from UHV.

avsteele3• 5 years ago

Great, thanks for the info

dumdumdumdum• 5 years ago

Using a starting point as a fixed reference and calibrated to the patterns of Earth’s magnetic field, data from a quantum navigation system will give us all the information we need to accurately determine where we are.

Why is the Earth's magnetic field important? And isn't that just as easy to "spoof" (if not more) than a GPS signal?

danielheath• 5 years ago

Magnetic field strength falls off rapidly - a spoofer would be extremely large and heavy to reach even a very short range. It’s not going to work against aircraft.

Animats• 5 years ago

DARPA has been funding work on better gyros and accelerometers for about 10 years now. MEMS gyros keep getting better. The good ones are down to a few degrees per hour.[1] That IMU/GPS is $3,386.09. Not down to the phone/vacuum cleaner price point yet.

This is nowhere near as good as the device described in the parent article, but it's good enough for a lot of applications. If you can get a GPS fix every few minutes, it's good enough for many nav applications.

(When we did a DARPA Grand Challenge vehicle in 2005, we had a MEMS gyro with over 10 deg/minute drift. That was too much for the mapping to work properly. We needed < 2 deg/minute for the laser scans to align. Better IMUs were back-ordered due to the Iraq war, and attempting to work around the problem with filters and a magnetic compass were not quite good enough.)

[1] https://www.mouser.com/ProductDetail/Parker-LORD/3DMGQ7

willis9362• 5 years ago

GPS is trivial to jam. Any exotic IMU has huge defense implications. Being able to miniaturize it would be a big deal.

ansgri• 5 years ago

I thought so for a long time, but then learned about spread-spectrum and frequency-hopping (with cryptographically randomized pattern) radio communication techniques which are employed in military-grade communications, and suddenly reliably jamming GPS without jamming literally everything becomes very hard.

sennight• 5 years ago

GPS is trivial to jam.

Not as trivial as jamming detection and countermeasures, so simple that it has found its way into base model commercial components. If you are in the air: use directional antennas - why are you listening to the ground? If you are on the ground: you get an easy 30deg arc pointing to the hostile transmitter... put a building or terrain between it and you.

baq• 5 years ago

Civilian GPS. Milspec encrypted FHSS or whatever are they using not so much unless you flood the whole spectrum.

Tempest1981• 5 years ago

The [1] link seems to need a matching query string:

https://www.mouser.com/ProductDetail/Parker-LORD/3DMGQ7?qs=s...

3DMGQ7 Data sheet: https://www.mouser.com/datasheet/2/1083/3dmgq7_gnssins_ds_0-...

asimjalis• 5 years ago

“Vaccum” in title should be “vacuum”.

stopagephobia• 5 years ago

I think a big question is how much $ to make one, AIRS is very good but damn expensive.

leptoniscool• 5 years ago

Would this be useful on Mars?

causi• 5 years ago

Article seems a little short on numbers. Just how slowly does this drift out of true?

011000112• 5 years ago

I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful. I would think that by limiting your image search space based on your likely position would make the problem even easier to solve.

Terrain based navigation is certainly nothing new(1950s?), so there is probably a large pool of research into it, but I wonder what's been done with recent pattern recognition advances?

upbeat_general2• 5 years ago

There’s still the issue of compute power required for a lot of the CV algorithms you’d want to use. There’s also the question of what data you are using; Satellite imagery is much harder to match with a ground perspective and ground imagery(e.g street view) is very tedious to collect and keep updated.

In areas with unique features (dense urban) localizing to within ~50ft has been demonstrated pretty robustly but more accurate methods of localization are a lot more variable and depend on the datasets, cameras (monocular vs stereo), compute, etc.

Dunedan• 5 years ago

I would think camera-based navigation would be fairly successful at this point. We can easily store large amounts of image and terrain data, and deep learning based image recognition systems are quite powerful.

Aside from the fact that the amount of data required for that would be orders of magnitudes larger than you can reasonably store, that wouldn't work at all in areas with little terrain features like deserts or the open sea.

Daniel_sk• 5 years ago

Or just a dense forest.

upbeat_general2• 5 years ago

It’s certainly conceivable that you could store a compressed representation of the image features. Especially if you’re operating in a more limited environment (e.g. a large metro area), it would be very feasible to only store extracted features from the image data that you could use for matching.

011000112• 5 years ago

We have literally been doing it since the 50s. Seems like technology has come quite far since then.

https://en.wikipedia.org/wiki/TERCOM

Here's a modern take on it: https://www.youtube.com/watch?v=U5Kr0YI3sec

Melkman• 5 years ago

Don't look down. Look up. That's been a navigation standard for years. Funnily enough replaced by GPS. https://airandspace.si.edu/collection-objects/astro-tracker-... That doesn't really work in a sub though. Also compasses (especially of the 3D variety) can be a great help.

basicplus22• 5 years ago

This reminds me of a spacecraft navigation system that employed an almost perfect sphere, that floated inside the centre of chamber that employed a detection system that corrected the spacecrafts direction to keep the sphere in the centre of the chamber. On the drawings it was referred to as the space crafts "consciousness"

Unfortunately i cannot find any reference to it anywhere.

sgtnoodle• 5 years ago

I remember that too. Maybe this? https://en.m.wikipedia.org/wiki/Gravity_Probe_B

basicplus22• 5 years ago

Thats cool! but not that.. the one I an thinking of used the device for course correction over vast distances

Vaccum-chamber quantum sensor device could allow GPS-free navigation

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