I read that the US military wants a modernized version of celestial navigation to reduce dependence on GPS. With modern light amplification technology it might be able to work during the day.
They have some of these on ships already.
Celestial Navigation for Drones
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Re: Celestial Navigation for Drones
#72Earlier quoted context omitted.
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…
That's a great idea. In the earlier days when they had about 2500 satellites in LEO I built a small visualizer from the fleet TLE data and it was remarkably simple with the skyfield library. If you're in the fringes of a GNSS denial area ADSB might be useful as well. Would need more hardware of course.
Doesn't ADS-B get the location from GNSS?
Re: Celestial Navigation for Drones
#73Perhaps 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…
Plenty of homework assignments in graduate level aerospace engineering courses that are right up the alley of this paper. Star trackers as backup for GNSS would be of great interest to maritime vessels worried about spoofing. So there are plenty of non-military use cases for these algorithms.
Re: Celestial Navigation for Drones
#74Earlier 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…
That is probably why Eric Schmidt (ex Google CEO) develops his AI combat drones in Estonia instead of US.
Re: Celestial Navigation for Drones
#75Earlier quoted context omitted.
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.
how hard would this be to set up for a total hardware noob? and how good or useful would the data be?
i know gaia data for instance is available for free but if one used just a homemade telescope could any useful celestial data be acquired?
Re: Celestial Navigation for Drones
#76Earlier 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?
Check out the CuriousMarc video series I linked under the OP, which gets into the sensor used and the encoding scheme.
it is kind of crazy and just a testament to people's creativity the plane basically flies using an ipdated version of whag the medieval ships used for navigation totally mind blown
Re: Celestial Navigation for Drones
#77Earlier quoted context omitted.
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.
The frequencies used in GPS: Yes. The frequencies used for celestial nav: No.
Re: Celestial Navigation for Drones
#78Fun 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).
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Re: Celestial Navigation for Drones
#79Fun 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…
- "pretty sure the first generation were pure-analog circuits"
This Wikipedia entry isn't what I had in mind, but it describes an interesting analog mechanism,
- "For guidance systems based solely on star tracking, some sort of recording mechanism, typically a magnetic tape, was pre-recorded with a signal that represented the angle of the star over the period of a day. At launch, the tape was forwarded to the appropriate time.[2] During the flight, the signal on the tape was used to roughly position a telescope so it would point at the expected position of the star. At the telescope's focus was a photocell and some sort of signal-generator, typically a spinning disk known as a chopper. The chopper causes the image of the star to repeatedly appear and disappear on the photocell, producing a signal that was then smoothed to produce an alternating current output. The phase of that signal was compared to the one on the tape to produce a guidance signal.[2]"
Re: Celestial Navigation for Drones
#80Earlier 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.
Lookup why torpedo's are almost universally 21" in diameter. The short version: because that was how big they were last time. There is no reason beyond 21" being usrd once upon a time and nobody wanting to break from it and have the old torpedos not work in the new boats.