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Celestial Navigation for Drones

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Re: Celestial Navigation for Drones

#111

Post by _joel »

Havoc wrote: post #103
littlestymaar wrote: post #98

Earlier quoted context omitted.

The full title is: > An Algorithm for Affordable Vision-Based GNSS-Denied Strapdown Celestial Navigation Emphasis mine. In what kind of context do you expect drones to operate in an area where GNSS is disabled by electronic warfare devices? Do you really think that a $400 cost is of any issue for military use?

> Do you really think that a $400 cost is of any issue for military use? If your name is Ukraine then yeah. Effectively halves the number of drones you can build

Sorry, this is wrong. They'd be based on long range UAV's - not short range FPVs. Ukraine have been building about half a dozen types of different long range drones and are producing a good number of those every day now (some with jets making them analogous to cruise missiles). They're much more expensive than a cheap FPV with an RPG warhead strapped to it.

Re: Celestial Navigation for Drones

#112

Post by GJim »

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…

Some clueless downvoting here!

Re: Celestial Navigation for Drones

#113

Post by Rallen89 »

cyberax wrote: post #82
Rallen89 wrote: post #51

Earlier quoted context omitted.

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)

Uhm, there are plenty of videos about making solid rocket fuel. Model rocketry doesn't need any special permits until you get to launching large rockets.

I guess once you have the permits it doesnt matter. With the nilered vids, they were more of the more hypergolic variety

Re: Celestial Navigation for Drones

#114

Post by kragen »

jcims wrote: post #2

I didn't see an explanation of what strapdown meant in this context, so I dug one up: "Traditional, stable-platform navigation systems commonly involve separate accelerators and fibers or laser-based gyroscopes, with all the components mechanically and rigidly mounted on a stable platform that is isolated from the moving vehicle. This leads to the drawbacks of large size, poor reliability, and high cost. In contrast,…

I wonder if you could dangle the star tracker below the drone on a long string, decoupling its attitude from the attitude of the drone. A kevlar or spectra string capable of supporting 100 grams would be 20μm in diameter; 3 meters of it would weigh a milligram, which is significantly less than gimbals. A small weight a couple of meters below the star tracker on a carbon-fiber-composite rod would seem to be able to stabilize its attitude further except in yaw.

Re: Celestial Navigation for Drones

#115

Post by fullspectrumdev »

littlestymaar wrote: post #105
Havoc wrote: post #103

Earlier quoted context omitted.

> Do you really think that a $400 cost is of any issue for military use? If your name is Ukraine then yeah. Effectively halves the number of drones you can build

> Effectively halves the number of drones you can build You're confusing the price tag of an FPV drone (for which this tech has no use, 4km precision is roughly the range of such drone, so even without a positioning device you'd get such a precision…) with the one of a long-range drone which is hundreds of magnitudes larger, even for Ukrainians.

FPV used in combat these days go a lot further than 4km, you can punch out to 25km+ with a good repeater setup easily, 10-15km with a good mast setup, and strikes using FPV quads out to 45km have been documented (but these are rare).

You just need to plan your battery selection and consider the electronic warfare environment to go the distance.

There’s also the optical fiber drones which come in spool lengths up to 20km…

Re: Celestial Navigation for Drones

#116

Post by fullspectrumdev »

notahacker wrote: post #30
myself248 wrote: post #15

Earlier quoted context omitted.

Years ago, an acquaintance developed an autonomous flight controller for "real" helicopters. Cyclic-collective-tailrotor types. It would work on a full-size cargo helo just as well as an R/C model. He released it online, because why not? Drones are cool. Some very nice gentlemen showed up and explained that he couldn't do that. He didn't get in any actual trouble that I'm aware of, but they "asked" him to take down t…

> A hacker's guide to ITAR would be an interesting document indeed. I suspect producing something called "a hacker's guide to ITAR" really would get you put on a list...

Knowing how stupid ITAR enforcement is, the guide would probably fall under ITAR :)

Re: Celestial Navigation for Drones

#117

Post by littlestymaar »

fullspectrumdev wrote: post #115
littlestymaar wrote: post #105

Earlier quoted context omitted.

> Effectively halves the number of drones you can build You're confusing the price tag of an FPV drone (for which this tech has no use, 4km precision is roughly the range of such drone, so even without a positioning device you'd get such a precision…) with the one of a long-range drone which is hundreds of magnitudes larger, even for Ukrainians.

FPV used in combat these days go a lot further than 4km, you can punch out to 25km+ with a good repeater setup easily , 10-15km with a good mast setup, and strikes using FPV quads out to 45km have been documented (but these are rare). You just need to plan your battery selection and consider the electronic warfare environment to go the distance. There’s also the optical fiber drones which come in spool lengths up to…

You're picking nits here. Again, you barely even need any kind of positioning system in an FPV, let alone a positioning system with 4km accuracy.

Such a system only make sense for use in long-ranged drones.

Re: Celestial Navigation for Drones

#118

Post by leoc »

A 2021 PopMech article about the US military's revival of interest in celestial navigation: https://www.popularmechanics.com/military/research/a36078957... It mentions a handheld system designed for special forces units to use, but I assume that that would incorporate something like a camera gyro stabiliser, presumably making the calculations easier than when relying on "strapdown" sensors.

Re: Celestial Navigation for Drones

#119

Post by cdot2 »

all2 wrote: post #63
littlestymaar wrote: post #53

Earlier quoted context omitted.

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 coalf…

I dislike the incorrect usage of "prehistoric". The Roman-era is not prehistoric.

Re: Celestial Navigation for Drones

#120

Post by cdot2 »

rkagerer wrote: post #90

4 km seems kind of coarse. Could you combine it with knowledge of satellite imagery or something to increase precision?

The drone on mars uses visual navigation based on known imagery of the terrain. I suspect that would be easier on this planet.
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