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The article isn't about highly precise INS development. It's about an INS so accurate it didn't need any external references, and says such applications haven't
by KennyBlanken 5y ago
The article isn't about highly precise INS development. It's about an INS so accurate it didn't need any external references, and says such applications haven't been necessary in decades.
Submarines still use external referencing. Unlike a missile, a submarine can use the earth's magnetic field to determine orientation in at least two axis. They can also reference fixed sound sources, know their depth, and so on.
I believe highly sensitive magnetometers were used to help correlate position - namely, the Navy had done surveys and so a record of magnetometer data could be 'fit' a track to the map by a computer.
That's the point of the article. So many navigation systems can use at least some sort of external reference, a completely independent positioning system isn't necessary.
- rkangel 5y agoGood INS actually involves combining several sources of information to produce a result better than any of them. A Kalman filter is the normal technique for this. You're right that magnetometry information is incorporated, but better and better INS help too. Laser Ring gyros (mentioned elsewhere) were an innovation that was first developed for submarines. I have no idea what they use now.
- KennyBlanken 5y agoThe AIRS has no external references beyond the initial position set by the ground station before the missile was fired. That was why AIRS had to be so incredibly low-drift. The point of the comment in the writeup is that the DoD found that there were almost no cases where at least some sort of external reference wasn't available and thus there was no point to having such an expensive, low-drift INS.