I'm sure there's a lot of novel stuff they're trying to do here, but the article seems to seriously skirt that inertial navigation systems are all around us and

I'm sure there's a lot of novel stuff they're trying to do here, but the article seems to seriously skirt that inertial navigation systems are all around us and in fact predate GPS by a lot. Doesn't seem to me they're re-inventing GPS, just making better INS.