I was wondering if anyone has ever implemented the Extended Kalman Filter in ArduPilot without GPS states?
I would like to implement a GPS-denied navigator that uses only the position of a known "home station" as a reference. Every time it lands at said "home station" the user can re-center the aircraft and re-calibrate the position accordingly to replace the GPS updates.
Thoughts?
Replies
The dynamic that makes the IMU + GPS EKF work is that the GPS error is constant over time, and the IMU positional error grows (from zero) with time. The current state of mems IMUs today is probably such that it's unwise to allow it such "freedom" for a flight. If you do not wish to use GPS for some reason, (for example, it's going to fly indoors) then perhaps you should look into other possible position-sensing alternatives such as range-to-objects or floor-watching camera, which can reign in on an IMU's error.
As the state of IMUs improves, they will soon be able to detect positional errors and attitude errors simply because of earth-rotation dynamics, however, that would require a degree of accuracy about 1000x better than the current state of the technology... sounds far off, but in the decade that I've been playing with mems, there has been a substantial improvement that would lead me to believe that it's really not so far off.