Comment by _flux
4 hours ago
Are there modern cheap IMUs that are able to hold position for some time available?
My understanding is that using plain accelerometers and gyros will drift quite soon due to noise, while some cars (e.g. Tesla) maintain their position quite well when doing to an underground parking structure and then coming back. So I actually do believe that they put a lot of weight to tracking wheels, which I believe would not accumulate that much error. (For more precise location they'd still need to use accelerometers to detect downhill/uphill, though.)
So I believe that the precision actually favors wheels, not IMUs.
In the underground parking case it doesn't actually matter too much if there's a certain % offset, because you're very likely driving a near-closed loop of some sort; and as you say, the wheel size ratio can be calibrated upon good GNSS data.
yeah Phones have pretty good IMUs. the TLDR is you combine accelerometers and gyros (preferably a bunch of them to minimize error) with GPS which gives you pretty accurate position and can also give you velocity data with some tricks)