1 - How to mix data from ultrasound range sensor, altimeter (barometric pressure sensor) and GPS to better estimate the altitude of a UAV platform?
2 - How to use the altitude estimate (from question 1) to create PID control loop for altitude hold for a hypothetical UAV platform?
Replies
Several of us did some work with the baro sensor, gps, and IMU, trying to use a simple kalman filter to fuse the data. Our conclusion is that the noise characteristic of the baro sensor, which is not white at all, makes this fairly useless.
We have generally found that the baro is far superior to gps for altitude. I think the best approach would be to simply use the sonar at very low altitudes, the baro above the sonar range, and mix the two in the middle.