I have to write an application for iphone that tracks the movement of the iphone itself, given its initial position, without ever using GPS. That is, I can only use data provided by the gyroscope and the accelerometer. The distances I need to measure are rather small and the precision I'm looking for is 40-50cm (~2 feet) at the very most.
Is this possible? If so, what's the best way to go about it? Also, do you know of any existing (and possibly open source) projects that have implemented this already?
Thanks a lot!
If you integrate the acceleration twice you get position but the error is horrible. It is useless in practice.
Here is an explanation why (Google Tech Talk) at 23:20. I highly recommend this video.
来源：https://stackoverflow.com/questions/6158176/track-small-movements-of-iphone-with-no-gps