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Celestial Navigation for Drones

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Re: Celestial Navigation for Drones

#11

Post by boscillator »

plasticchris wrote: post #3
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,…

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.

Re: Celestial Navigation for Drones

#12

Post by maxglute »

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.

Re: Celestial Navigation for Drones

#13

Post by areoform »

pvg wrote: post #9
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…

You're definitely on the list of people worried about being on lists now.

But that's the bestest list!

Re: Celestial Navigation for Drones

#14

Post by the__alchemist »

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.

I would assume the same. Operation in GNSS-denied environments is critical for military navigation systems. Comparatively, for civilian uses, it's an addon that provides low accuracy, and potentially high development or equipment cost (Maybe not for a cel nav camera, but for Ring Laser Gyro INSs etc)

GNSS is very accurate, and receivers are cheap, but its reliant on satellite signals makes relying on it a liability in adversarial uses.

Cel nav isn't self-contained in the way an INS is, because you need a clear LOS to the stars. But, it's useful on a clear night when your GPS is jammed.

Re: Celestial Navigation for Drones

#15

Post by myself248 »

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…

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 the published code, and definitely not fix any of the bugs it had.

So, yeah, you're not wrong.

There are nuances to the rules, involving things that're openly published online, but I don't understand it in the least. A hacker's guide to ITAR would be an interesting document indeed.

Re: Celestial Navigation for Drones

#16

Post by hnuser123456 »

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…

I'm sure there are thousands of datasets of the night sky, and a camera, gyrometer (to get camera angles), clock, and basic image recognition/pattern matching is all you'd need.

Re: Celestial Navigation for Drones

#17

Post by mapt »

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 perfect vertical attitude sensing coming off the autopilot IMU, you can do it purely photometrically.

The limitation is that this is a dawn/dusk thing, in the middle of the night there isn't a ton of light reflected and in the day you're limited by scattered daylight.

EDIT: Medium orbit satellites outside Earth's umbra but within view still provide some sort of visual fix. I wonder what the math is like for the GSO belt at midnight?

EDIT2: Or the Moon.

Re: Celestial Navigation for Drones

#18

Post by the__alchemist »

biofox wrote: post #10
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…

You will likely raise a flag somewhere if you publicise what you are doing, but I highly doubt there would be any issues if you're working on this in private as a hobby. As for chemicals, I can personally vouch that it is a terrible idea to order reagents (or even chemistry equipment) as an individual. I tried to teach myself organic synthesis in the summer before starting my doctoral studies, and ended up with MIB s…

LLC or nonprofit, with a business address. At least for bio reagants, they won't ship to you otherwise.

Re: Celestial Navigation for Drones

#19

Post by 7thpower »

biofox wrote: post #10
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…

You will likely raise a flag somewhere if you publicise what you are doing, but I highly doubt there would be any issues if you're working on this in private as a hobby. As for chemicals, I can personally vouch that it is a terrible idea to order reagents (or even chemistry equipment) as an individual. I tried to teach myself organic synthesis in the summer before starting my doctoral studies, and ended up with MIB s…

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

Re: Celestial Navigation for Drones

#20

Post by RandomBacon »

pvg wrote: post #9
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…

You're definitely on the list of people worried about being on lists now.

The only people not on any lists, are boring people.
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