Mag cal: automatically disable internal mags if external ones are available

[bresch]

Solved Problem

Magnetometers inside the autopilot are almost always highly affected by varying magnetic fields generated by the drone due to their location inside the drone.
The internal mag is useful for initial autopilot bench testing, before it gets integrated inside a drone, and when performing the calibration of the external one to automatically detect the rotation parameter. However, it then only causes issues as it often triggers false warnings (mag inconsistency) and in case of an in-air failure of the external mag, a fallback to the internal mag can lead to worse performance than not using a mag at all.

Solution

Automatically disable all internal mags just after calibration if an external one is available.

Changelog Entry

For release notes:

New parameter: -
Documentation: todo

Test coverage

Bench tested

[github-actions]

🔎 FLASH Analysis

px4_fmu-v5x [Total VM Diff: 152 byte (0.01 %)]

    FILE SIZE        VM SIZE    
--------------  -------------- 
+0.0%    +152  +0.0%    +152    .text
  +1.0%     +64  +1.0%     +64    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.8%     +60  +0.8%     +60    ../../src/modules/commander/mag_calibration.cpp
  +2.2%     +28  +2.2%     +28    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +0.0%      +5  +0.0%      +5    [section .text]
  +0.2%      +3  +0.2%      +3    ../../src/systemcmds/ver/ver.cpp
  -0.0%      -4  -0.0%      -4    ../../src/modules/control_allocator/ControlAllocator.cpp
  -0.1%      -4  -0.1%      -4    ../../src/modules/ekf2/EKF/yaw_estimator/EKFGSF_yaw.cpp
+0.0%     +56  [ = ]       0    .debug_abbrev
   +11%     +56  [ = ]       0    ../../src/lib/version/version.c
-0.0%      -8  [ = ]       0    .debug_aranges
  -5.0%      -8  [ = ]       0    ../../src/lib/version/version.c
+0.0%     +16  [ = ]       0    .debug_frame
+0.0%    +442  [ = ]       0    .debug_info
  +0.1%     +27  [ = ]       0    ../../src/lib/sensor_calibration/Magnetometer.cpp
  -0.2%      -4  [ = ]       0    ../../src/lib/version/version.c
  +0.1%     +50  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +0.2%    +150  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +0.0%     +27  [ = ]       0    ../../src/modules/mag_bias_estimator/MagBiasEstimator.cpp
  +0.0%     +27  [ = ]       0    ../../src/modules/sensors/sensors.cpp
  +0.1%    +138  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.0%     +27  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
+0.0%    +334  [ = ]       0    .debug_line
  -1.3%     -25  [ = ]       0    ../../src/lib/version/version.c
  +0.6%     +30  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +1.1%    +165  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +0.9%    +168  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  -0.0%      -2  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
  -0.2%      -2  [ = ]       0    task/task_cancelpt.c
+0.0%    +183  [ = ]       0    .debug_loc
  -0.0%     -15  [ = ]       0    ../../src/modules/commander/Commander.cpp
  -1.3%     -86  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +0.4%    +113  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  -0.1%     -15  [ = ]       0    ../../src/modules/mag_bias_estimator/MagBiasEstimator.cpp
  +0.1%     +15  [ = ]       0    ../../src/modules/sensors/sensors.cpp
  +0.5%    +141  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.0%     +30  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
+0.0%    +233  [ = ]       0    .debug_ranges
  -2.6%      -8  [ = ]       0    ../../src/lib/version/version.c
  +3.3%     +64  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +1.2%     +80  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +1.3%     +96  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +1.6%      +1  [ = ]       0    task/task_cancelpt.c
+0.0%     +64  [ = ]       0    .debug_str
  +1.4%     +64  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
-1.5%    -152  [ = ]       0    [Unmapped]
+0.0% +1.29Ki  +0.0%    +152    TOTAL

px4_fmu-v6x [Total VM Diff: 144 byte (0.01 %)]

    FILE SIZE        VM SIZE    
--------------  -------------- 
+0.0%    +144  +0.0%    +144    .text
  +1.0%     +64  +1.0%     +64    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.8%     +60  +0.8%     +60    ../../src/modules/commander/mag_calibration.cpp
  +2.2%     +28  +2.2%     +28    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  -0.0%      -4  -0.0%      -4    ../../src/modules/control_allocator/ControlAllocator.cpp
  -0.1%      -4  -0.1%      -4    ../../src/modules/ekf2/EKF/yaw_estimator/EKFGSF_yaw.cpp
+0.0%     +56  [ = ]       0    .debug_abbrev
   +11%     +56  [ = ]       0    ../../src/lib/version/version.c
-0.0%      -8  [ = ]       0    .debug_aranges
  -5.0%      -8  [ = ]       0    ../../src/lib/version/version.c
+0.0%     +16  [ = ]       0    .debug_frame
+0.0%    +442  [ = ]       0    .debug_info
  +0.1%     +27  [ = ]       0    ../../src/lib/sensor_calibration/Magnetometer.cpp
  -0.2%      -4  [ = ]       0    ../../src/lib/version/version.c
  +0.1%     +50  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +0.2%    +150  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +0.0%     +27  [ = ]       0    ../../src/modules/mag_bias_estimator/MagBiasEstimator.cpp
  +0.0%     +27  [ = ]       0    ../../src/modules/sensors/sensors.cpp
  +0.1%    +138  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.0%     +27  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
+0.0%    +342  [ = ]       0    .debug_line
  -1.3%     -25  [ = ]       0    ../../src/lib/version/version.c
  +0.6%     +30  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +1.1%    +165  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +0.9%    +168  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  -0.0%      -2  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
  +0.5%      +6  [ = ]       0    task/task_cancelpt.c
+0.0%    +198  [ = ]       0    .debug_loc
  -0.0%     -15  [ = ]       0    ../../src/modules/commander/Commander.cpp
  -1.3%     -86  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +0.4%    +113  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +0.1%     +15  [ = ]       0    ../../src/modules/sensors/sensors.cpp
  +0.5%    +141  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  +0.0%     +30  [ = ]       0    src/modules/mavlink/modules__mavlink_unity.cpp
+0.0%    +230  [ = ]       0    .debug_ranges
  -2.6%      -8  [ = ]       0    ../../src/lib/version/version.c
  +3.3%     +64  [ = ]       0    ../../src/modules/commander/HealthAndArmingChecks/checks/magnetometerCheck.cpp
  +1.2%     +80  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
  +1.3%     +96  [ = ]       0    ../../src/modules/sensors/vehicle_magnetometer/VehicleMagnetometer.cpp
  -3.0%      -2  [ = ]       0    task/task_cancelpt.c
+0.0%     +64  [ = ]       0    .debug_str
  +1.4%     +64  [ = ]       0    ../../src/modules/commander/mag_calibration.cpp
-0.2%    -144  [ = ]       0    [Unmapped]
+0.0% +1.31Ki  +0.0%    +144    TOTAL

Updated: 2025-02-14T14:54:14

[dagar]

Nice idea, I just wonder if we should do something basic to validate the external is alive and "good"?

[hamishwillee]

@bresch This will require docs update. The whole calibration doc will need some minor work, but in particular we will need to update https://docs.px4.io/main/en/config/compass.html#additional-calibration-configuration and the sub topic on disabling a compass

My assumption is that if the internal compass is disabled after calibration it is still calibrated. So the section would change from "Disable a Compass" to "Re-enable a compass" and include explanation that often this is worse than nothing so explain when/why you would do it.

[dakejahl]

This makes sense, I think many users already disable the internal mag after calibration anyway. The cherry on top would be a sensor status tab in QGC Vehicle page. Right now it's not obvious to users what sensors are enabled, functional, and which calibration parameters corresponds to which device.

[bresch]

The cherry on top would be a sensor status tab in QGC Vehicle page

oh yes, that could be nice to have

which calibration parameters corresponds to which device.

Yes, if QGC could show you something like "Mag 1 (external): IST8310" and the calibration values.

[sfuhrer]

Code looks clean and I bench tested it a bit.