
NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Frank Reed
Date: 2013 Apr 12, 10:10 -0700
Thanks for the link, Richard (http://www.gpsworld.com/extreme-miniaturization-seven-devices-one-chip-to-navigate-without-gps/).
This appears to be an enhancement (radically miniaturized) of very short-term inertial navigation units which are already found in many applications. As I understand it, the idea is to provide a brief bridge when GPS signals cannot be received for some dozens of seconds (for longer periods... a couple of minutes? the IMU's orientation drifts to the point where it is no longer of use for navigation). Many car navigation systems have something similar, but of course far less sophisticated. They have automatic dead reckoning systems that will update the displayed position when GPS positions are unavailable (like when driving in a tunnel). Dead reckoning is normally all that's needed for cars since their wheels are usually in direct, non-slipping contact with the ground. As long as you don't need to update your car's position while in freefall or riding on a moving platform, velocity integration (DR) is enough and acceleration integration (as in this IMU) is not necessary.
-FER
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