Even a perfect sensor will accumulate errors in the nav solution over time because there’s no such thing as a perfect gravity model. No free-running INS will ever replace GPS long term. This shit is so frustrating to see in the press.
Especially since, to calculate current location, it needs an input of initial location (i.e. it needs GPS coordinates to begin with so it can track direction and velocity relative to that initial position). You can’t replace something you depend upon.
the initial location doesn’t need to be GPS, just a known anchor location. Which is trivial to implement in the case of trains, since stations don’t move that drastically.
But wouldn’t you scramble the precision with that? Stations can be quite big and anchoring to the station location means you already start with an offset to your location.
Depending on the accuracy over time, they could pinpoint a location while the user is sleeping and than use that as an anchor for the day.
But everything about that is speculative; let’s see where this goes first.
you’re thinking anywhere on the platform, I’m suggesting a known place near a station by which the train passes and its location - at that moment - is known.
All the system needs is a ground-truth location after a certain amount of time. GPS is just a cheap and convenient way to do it almost anywhere, but this location correction doesn’t need to be satellite-based at all.
Even a perfect sensor will accumulate errors in the nav solution over time because there’s no such thing as a perfect gravity model. No free-running INS will ever replace GPS long term. This shit is so frustrating to see in the press.
Especially since, to calculate current location, it needs an input of initial location (i.e. it needs GPS coordinates to begin with so it can track direction and velocity relative to that initial position). You can’t replace something you depend upon.
the initial location doesn’t need to be GPS, just a known anchor location. Which is trivial to implement in the case of trains, since stations don’t move that drastically.
But wouldn’t you scramble the precision with that? Stations can be quite big and anchoring to the station location means you already start with an offset to your location.
Depending on the accuracy over time, they could pinpoint a location while the user is sleeping and than use that as an anchor for the day.
But everything about that is speculative; let’s see where this goes first.
you’re thinking anywhere on the platform, I’m suggesting a known place near a station by which the train passes and its location - at that moment - is known.
All the system needs is a ground-truth location after a certain amount of time. GPS is just a cheap and convenient way to do it almost anywhere, but this location correction doesn’t need to be satellite-based at all.