PR: baro auto calibration

[haumarco]

Solved Problem

When we have multiple barometers, we currently do not perform any calibration. There already exists a do_baro_calibration function, but I guess nobody used it since the function call of getAltitudeFromPressure had the wrong arguments.

This fix adds a calibration procedure for handling relative offsets between multiple baros, avoiding vertical position jumps when one switches between baros mid-flight.
When GNSS is set as the height reference, the calibration offset is calculated in respect to the absolute height (currently in baro-bias).

The offset is now stored in the offset parameter since it's static and not a changing bias.

I checked various flight logs with durations of more than 3000s and could not observe non systematic drifts between baros. Therefore frequent recalibration does not make any sense.

with GNSS, calibration triggered at t=34:

Switch from baro0 to baro1:

---

Feedback needed:
I now trigger the calibration 1s after the first baro measurement. At this point in time the GNSS is not sending any data yet. Therefore a manual trigger from the user is necessary to perform an absolute calibration. This wouldnt be a problem though, since the baro bias would still handle this case... Should I change something about this?

[github-actions]

🔎 FLASH Analysis

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Updated: 2025-01-15T17:06:36

[dagar]

I like the idea, but how about...

1. Doing it from sensors/vehicle_air_data where you already have access to all sensor_baro subscriptions, calibrations, and vehicle_air_data output. https://github.com/PX4/PX4-Autopilot/blob/main/src/modules/sensors/vehicle_air_data/VehicleAirData.cpp
2. Use vehicle_gps_position (or even all sensor_gps publications) rather than depend on an EKF2 dependency.

[haumarco]

I like the idea, but how about...

1. I first started to implement it in VehicleAirData.cpp but moved it to the commander to keep a nice workflow for the manually triggered calibration procedure. In the sensors module it would also create an overhead because i want to collect data for some time (list of measurement, start/stop handling), in the commander it just runs in a separate thread.
2. not sure what you mean, currently it subscribes to sensor_gps?