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Celestial Navigation for Drones

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Re: Celestial Navigation for Drones

#61

Post by fooblaster »

alexpotato wrote: post #29

Fun fact: The SR-71 and U2 planes had automated celestial navigation systems b/c GPS wasn't around when they came out. There a story in the book about Lockheed Martin's Skunk Works where they mention turning on the system while one of the planes was in the hangar and it locked on to a hole in the roof (sun was shining through the hole and system thought it was a start).

why would you think this has stopped? All military aircraft and missiles need to operate in gps denied environments and near universally have dead reckoning or celestial navigation still.

Re: Celestial Navigation for Drones

#62

Post by Onavo »

areoform wrote: post #5

Perhaps I am too paranoid, but I've been told to avoid doing any DIY in this field of study. Apparently, or so I'm told, out of the many, many ways to end up on a list — building a working celestial navigation system can lead to some very inconvenient outcomes. Second, only to ordering large quantities of certain chemicals online. Is this true? ——— EDIT - from the paper, this is incorrect, > The introduction of GPS c…

These days celestial navigation is trivial. See my comment here

https://news.ycombinator.com/item?id=42695079

Re: Celestial Navigation for Drones

#63

Post by all2 »

littlestymaar wrote: post #53
alexpotato wrote: post #34

Earlier quoted context omitted.

Reminds me of the "the distance between the rails of a railway are due to the width of Roman horse drawn carts" story.

Isn't that one a hoax though?

There are a few standards for rail-line widths. I know the US is on one standard (I think the narrow width lines died out almost 100 years ago at this point). I know that Europe has two, or maybe more.

https://en.wikipedia.org/wiki/Standard-gauge_railway Relevant passage

    A popular legend that has circulated since at least 1937[8] traces the origin of the 1,435 mm (4 ft 8+1⁄2 in) gauge even further back than the coalfields of northern England, pointing to the evidence of rutted roads marked by chariot wheels dating from the Roman Empire.[a][9] Snopes categorised this legend as "false", but commented that it "is perhaps more fairly labeled as 'Partly true, but for trivial and unremarkable reasons.'"[10] The historical tendency to place the wheels of horse-drawn vehicles around 5 ft (1,524 mm) apart probably derives from the width needed to fit a carthorse in between the shafts.[10] Research, however, has been undertaken to support the hypothesis that "the origin of the standard gauge of the railway might result from an interval of wheel ruts of prehistoric ancient carriages".[11]

Re: Celestial Navigation for Drones

#64

Post by progbits »

Neywiny wrote: post #58
alexpotato wrote: post #34

Earlier quoted context omitted.

Reminds me of the "the distance between the rails of a railway are due to the width of Roman horse drawn carts" story.

My preferred one for EE folks is that reportedly the first Arduino boards (now 20 years old?) had a mistake in their eCAD where the second pair of headers was 0.05 instead of 0.1" apart. But it was too late by the time they caught it. And now, 20 years later, even high end microcontroller boards ship with that same gap to be compatible.

Small correction, one pair is 0.2" apart (so skipping one 0.1" pitch space), but the other is 0.16".

Re: Celestial Navigation for Drones

#65

Post by phoronixrly »

maxglute wrote: post #12

Ctrl+F and 0 results for munitions or bombs. Seems like this is really about $25 controller gets drones to within 4km in GPS denied enviroments, after which a $50 infrared camera + DSMAC find targets to hit.

Don't get distracted https://news.ycombinator.com/item?id=42388354

Re: Celestial Navigation for Drones

#66

Post by andylynch »

perihelions wrote: post #32
alexpotato wrote: post #29

Fun fact: The SR-71 and U2 planes had automated celestial navigation systems b/c GPS wasn't around when they came out. There a story in the book about Lockheed Martin's Skunk Works where they mention turning on the system while one of the planes was in the hangar and it locked on to a hole in the roof (sun was shining through the hole and system thought it was a start).

And, it's a bit older than that: the SR-71's derived from ICBM targeting systems, https://en.wikipedia.org/wiki/Missile_guidance#Astro-inertia... ( "the latter of which was adapted for the SR-71..." ) (Actually the very first one, in that history, was an intercontinental cruise missile —a jet weapon that slightly predated (~1958) rockets powerful enough to cross oceans. ICBM's came a bit later. I'm pretty sure the fi…

I understand these still do incorporate celestial navigation.

Since GPS is quite likely going to be unavailable at the time of use.

Re: Celestial Navigation for Drones

#67

Post by mpetroff »

joshvm wrote: post #46
gunian wrote: post #38

Earlier quoted context omitted.

That's insanely cool what kind of cameras / telescope are strong enough to do that? My guess is it was primarily hardware and not software bacuse of compute limits Did the planes have to fly above clouds?

It would work on the ground, I believe the pilots (normally) had to get a fix before takeoff. You do need to see the sky without cloud cover, but spy satellites were less of a concern back then so less risk of being overflown during a daylight setup. The cameras are basically visible telescopes with very narrow fields of view and good baffling. Only a few stars are bright enough that you can sight off them, but it ca…

BICEP3 actually uses a >20 year old CCD camera with analog video output (BICEP Array uses newer cameras, with more modern sensors). Daytime star pointings are possible by using a low-pass filter to block visible light and take advantage of the sensitivity of CCD / CMOS sensors to the near infrared, where the daytime sky is more transparent, combined with baffling.

Re: Celestial Navigation for Drones

#68

Post by all2 »

KineticLensman wrote: post #6
adolph wrote: post #4

I wonder if GPS and the like will be used more for their clock features than for position. The emissions celestial bodies are perfect fiducial markers [0,1], but connecting them to position still requires accurate timekeeping [2], as the paper notes: Provided the use of an accurate clock, the results presented in this paper will not degrade over time. 0. https://www.twz.com/17207/sr-71s-r2-d2-could-be-the-key-to-w...…

They are perfect markers only as long as you can see them. Clouds and fog are your enemies here

I presume radio signal or certain frequencies of thermal would be viable for adverse weather conditions.

Re: Celestial Navigation for Drones

#70

Post by UltraSane »

boscillator wrote: post #11
plasticchris wrote: post #3

Earlier quoted context omitted.

Or in short, the sensors are strapped down to the platform being measured - like your phone’s sensors for example.

Yes! It's in contrast to gimbaled systems. Putting the measuring instrument on a gimbal simplifies the math and often improves accuracy, but at the expense that you need this large moving object that needs more power.

The ultimate example of this is the incredibly accurate and expensive and complicated floating Advanced Inertial Reference Sphere used on the Peacekeeper ICBM.

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

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