I’m keen to understand how a SatNav works out how to get me from A to B.
I understand at a basic level how it receives a number of GPS signals so can work out where it is. I’d like to know what it then does to navigate me through all the different road systems to get me to my destination.
In: Technology
i am not an expert….but…
the computer in the sat-nav, armed with a lot of data, attempts to create a route from A to B. There are likely an insane number of routes between the two destinations, so the problem is broken down.
Imagine taking your country, and dividing it up into big squares. So now, the path from A->B is relatively easy. But big squares have no detail. So now the squares originally chosen, are sub-divided into littler squares, and the same approach is taken. Repeat until the relevant scale level is reached.
The above doesnt take into account, for example motorway/freeway, that may take a longer route, but be faster in time. So the code in the satnav will try out various shortest and quickest routes.
At the very local level, with lots of roads, intersections and other normal driving scenarios, it will use a different approach, maybe trying out a lot of permutations.
How it does it, appears magic. The earliest satnavs had underpowered CPUs and took forever to compute a route. Modern satnavs have a lot more power and sophistication.
So, yes, it is amazing what they do, but ultimately its a divide-and-conquer approach to breaking down a journey, stitching together the pieces, and checking other items (like traffic delays), to decide an optimal route.
Even a single road is likely to be broken up into multiple sub-segments, e.g. due to curvature of the road.
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