Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Celestial Navigation for Drones

mdpi.com

Post reply on HN
Print view View original

51–60 of 130 posts

Re: Celestial Navigation for Drones

#51

Post by Rallen89 »

mavamaarten wrote: post #44
7thpower wrote: post #19

Earlier quoted context omitted.

Please tell me there is a blog post or something documenting this experience. Sounds like a fun read.

I remember watching a video about a dude who was building a mothership-launched glide drone that could land using camera vision. The idea was something like "the highest egg drop" or something like that. He was speaking with academics about his idea, who quickly told him to stop whatever he was doing because that would effectively be a forbidden military device. Guided artillery, basically. Sadly I don't remember who…

Happened to codyslab, videos taken down now (but still on archive.org) of a uranium purification process and possibly nilered,no way to prove it but he had a 'making rocket fuels: part 1' that was never followed p on. Not totally sure though as people like BPS space on yt have some pretty in depth tutorials on solid rocket motors (does explicitly censor how to make the ignition component)

Re: Celestial Navigation for Drones

#52

Post by rich_sasha »

GJim wrote: post #43
rich_sasha wrote: post #33

Earlier quoted context omitted.

I guess timekeeping is relatively easy? These systems would only operate independently for a few hours tops. I would imagine even a standard quartz movement would be accurate enough.

> I guess timekeeping is relatively easy...... would imagine even a standard quartz movement would be accurate enough. Good Lord! How wrong can you get! Very precise timing (often taken from GNSS for convenience) is needed for much of the modern word, from IP, cellular and DAB networks, to AC phase matching the electrical mains grid. Quartz clocks are nowhere near accurate enough for these purposes. This government r…

In the context of position keeping I think it's not too bad.

If we focus on longitude, where timing I guess matters more, the equator moves at a speed of about 0.46 km/s. So I guess being out by 1 second translates to precisely 0.46km error. That's second order compared to the stated error of 4 km, and it will be smaller still away from the equator.

I'm working off the assumption that such a drone can sync up to an accurate time source at launch, and then only needs maintain good timekeeping for its time in the air. I guess without the accurate initial time source, it gets bad. Being a minute out is suddenly 30km of latitude direction away.

Re: Celestial Navigation for Drones

#53

Post by littlestymaar »

alexpotato wrote: post #34
perihelions wrote: post #32

Earlier quoted context omitted.

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…

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?

Re: Celestial Navigation for Drones

#54

Post by withinboredom »

GJim wrote: post #43
rich_sasha wrote: post #33

Earlier quoted context omitted.

I guess timekeeping is relatively easy? These systems would only operate independently for a few hours tops. I would imagine even a standard quartz movement would be accurate enough.

> I guess timekeeping is relatively easy...... would imagine even a standard quartz movement would be accurate enough. Good Lord! How wrong can you get! Very precise timing (often taken from GNSS for convenience) is needed for much of the modern word, from IP, cellular and DAB networks, to AC phase matching the electrical mains grid. Quartz clocks are nowhere near accurate enough for these purposes. This government r…

> Our dependence on GNSS for timing almost dwarfs that for navigation.

Galileo satellites also now sign the timestamp (IIRC) via a Merkle tree so you know it isn't spoofed.

Re: Celestial Navigation for Drones

#55

Post by maxglute »

mapt wrote: post #17
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.

Thanks for the summary. I suspect you could get this to FAR higher accuracy if you combined it with a recent upload of Starlink et al LEO constellation ephemera, an initial GPS fix at launch, and a planned flight path, because LEO constellations are bright foreground objects (high location-specific parallax differences against background stars) at apparent magnitude of about 5.0. This is simultaneously not reliant on…

IMO could synergize well for higher end celestia navigation - there are optics sensors for day time tracking, but daylight sensitivity is limitation, perhaps much less so when fixed to starlink. So maybe feasible $$$ hardware can make daylight celestial starlink navigation workable.

Bringing component costs down seems like it would be much more useful for increasing capabilities / proliferating of lower end loitering munitions. You can already pack redundant navigation systems in more expensive platforms that gets them to area of operations. But being able to replace $20,000 inertial navigation system with $200 board + IR camera makes a lot of somewhat cheap smart munitions much smarter, and mitigates a lot of expensive electronics warfare platforms.

Starlink ubiquity does seem to open a lot of indirect strategic applications, i.e. research using starlink transmissions as bi/multistatic illumination source to detect stealth flyers.

Re: Celestial Navigation for Drones

#56

Post by wolfram74 »

munchler wrote: post #49
wolfram74 wrote: post #7

Earlier quoted context omitted.

I've also been told learning too much about linux or the nuclear reactions in power plants or bombs puts you on a list. I just assume I'm on several.

Learning too much about Linux puts you on a list? That can't be a thing. Isn't Linux itself entirely a civilian project?

The rationale mentioned was it was under the subheading of people interested in strong encryption, people who care about being unobservable might have something to hide. Maybe it's a good list? People who you might want to ramp up a new Bletchley Park? Probably not.

Re: Celestial Navigation for Drones

#57

Post by fisherjeff »

rich_sasha wrote: post #52
GJim wrote: post #43

Earlier quoted context omitted.

> I guess timekeeping is relatively easy...... would imagine even a standard quartz movement would be accurate enough. Good Lord! How wrong can you get! Very precise timing (often taken from GNSS for convenience) is needed for much of the modern word, from IP, cellular and DAB networks, to AC phase matching the electrical mains grid. Quartz clocks are nowhere near accurate enough for these purposes. This government r…

In the context of position keeping I think it's not too bad. If we focus on longitude, where timing I guess matters more, the equator moves at a speed of about 0.46 km/s. So I guess being out by 1 second translates to precisely 0.46km error. That's second order compared to the stated error of 4 km, and it will be smaller still away from the equator. I'm working off the assumption that such a drone can sync up to an a…

Plus I think most decent quartz oscillators have a drift measured in single-digit PPM (or less) so even 100ms error over a single sortie would be surprising.

Re: Celestial Navigation for Drones

#58

Post by Neywiny »

alexpotato wrote: post #34
perihelions wrote: post #32

Earlier quoted context omitted.

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…

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.

Re: Celestial Navigation for Drones

#59

Post by jenny91 »

rich_sasha wrote: post #33
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...…

I guess timekeeping is relatively easy? These systems would only operate independently for a few hours tops. I would imagine even a standard quartz movement would be accurate enough.

Depends on what you're using time for. If you are doing advanced anti-jamming for comms for instance, you want extremely accurate timing (more accurate means you can frequency hop faster and do better anti-jamming).

Re: Celestial Navigation for Drones

#60

Post by jjk166 »

withinboredom wrote: post #45
GJim wrote: post #43

Earlier quoted context omitted.

> I guess timekeeping is relatively easy...... would imagine even a standard quartz movement would be accurate enough. Good Lord! How wrong can you get! Very precise timing (often taken from GNSS for convenience) is needed for much of the modern word, from IP, cellular and DAB networks, to AC phase matching the electrical mains grid. Quartz clocks are nowhere near accurate enough for these purposes. This government r…

I mean, considering celestial navigation was a thing long before we had accurate clocks… I’d venture they aren’t wrong at all. Or did you forget that people have been doing celestial navigation by hand for over two millennia?

Celestial navigation actually drove the development of accurate clocks

https://timeandnavigation.si.edu/navigating-at-sea/longitude...

Quartz clocks didn't overtake chronometers in terms of accuracy until the mid 20th century, and chronometers will still beat regular crystals like you'd find in cheap electronics.

Post reply on HN