Altitude sensing behavior and EK3_SRC1_POSZ value

ArduCopter Copter 4.6
1

According to the parameter list, there’s no default value (for copter) for the EK3_SRC1_POSZ parameter.

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Looking at old log files - EK3_SRC1_POSZ is always set to “1” - for “Baro”.

Does EK3 fuse GPS data with barometer data for determining altitude?

If so - how is it configured/controlled?

In some locations I operate, there is poor GPS reception, and I wouldn’t want GPS altitude data to corrupt the EK3 determination of altitude. So in those cases, I would want to disable any fusing.

And of course, this would affect indoor flights.

Thanks!

1 Like
2

Search the docs for EKF info. (Hint: Copter → Advanced Configuration)

If that doesn’t answer for you, post back with further questions?

3

Hi @jstroup1986,

The default value for EK3_SRC1_POSZ is 1 (Baro) and the default value does appear in Mission Planner’s parameter. I’m not sure if the defaults ever appear in the full parameter list on the wiki (I don’t see defaults anywhere).

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If EK3_SRC1_POSZ = 3 (GPS) and the GPS fails for whatever reason AP will fall back to using the barometer.

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Looking at the code, my understanding is that there is no fusion occurring. Rather, it is one or the other. And from what I can tell, if EK3 is set to GPS and then there is no GPS data for 2 seconds or the GPS accuracy gradually degrades, then code switches to baro (hardcoded decision).