II used to work with magnetometers for ten years, especially fluxgate magnetometers. It did not aroused to my mind, that magnetic fields can be used for navigation. For me it was a kind of nuisance and I tried to find a clean magnetic environment for my testing.
IndoorAtlas has a solution:
Geomagnetic fields and ferromagnetic materials can be used for navigation and positioning, when GPS is not available, especially indoor environment. Magnetic maps has to be created first:
https://www.youtube.com/watch?v=jzoTyC7cZbE
Every smartphone has a magnetometer that also can work as a compass,
Technology is available. IndoorAtlas has a Software Development Kit (SDK) that is free.
https://www.youtube.com/watch?v=fBwC5ZxfPwQ
I also want to present one application. For example visitors had difficulties to navigate in hospital corridors. It is perfect for magnetic navigation. Typically indoor navigation is based on Wi-Fi stations, that is inaccurate and need hardware.
https://www.youtube.com/watch?v=J6I-jElYBss
My plan is to learn Android IndoorAtlas SDK and transfer it Ubuntu Linux and Python. It is very challenging project. In the first place I will just tie my smartphone to the Eddie rover.
Reference:
Simultaneous Lokalization And Mapping Using The Indoor Magnetic Field