Acc calibration

[adrianmiriuta]

Acc calibration fails to level quad !

version

ButterFlight / HELIOSPRING (HESP) 3.5.1 Apr 10 2018 / 21:13:41 (49c2ac986) MSP API: 1.40

IMU-F Version: 106

[orneryd]

Calibration doesn't "level" the quad. it levels it relative to gravity. If a table is 1 degree off it will be 1 degree off.

[adrianmiriuta]

@orneryd If the FC is mounted with a few degrees misalignment (2° roll 3°pitch), or the MPU is soldered with a small angular offset ... You have to correct this offsets trough acc Calibration. (put quad level and calibrate !) Else you will get a offset in Attitude , and a drift in Level and Horizon modes !

[orneryd]

calibrating it won't make it flat in the UI, calibrating it will set the trims. if you go to the cli and type "set acc" you will see the trims set to compensate for the angle.

On Thu, Apr 12, 2018 at 9:41 PM, adrianmiriuta notifications@github.com wrote:

@orneryd https://github.com/orneryd If the FC is mounted with a few degrees misalignment (2° roll 3°pitch), or the MPU is soldered with a small angular offset ... You have to correct this offsets trough acc Calibration. (put quad level and calibrate !) Else you will get a offset in Attitude , and a drift in Level and Horizon modes !

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[adrianmiriuta]

@orneryd I see , but it should level the Attitude quaternion,

It only fails to do so because someone deactivated acc handling in imuCalculateEstimatedAttitude bool useAcc = false;

This means Attitude is only calculated from gyro and will drift !

I tried to patch that (PR #112), but it was reverted !

[orneryd]

I fixed that in the refactor i did here:

    quaternion vGyroAverage;
    gyroGetAverage(&vGyroAverage);

    quaternion vAccAverage;
    if (accGetAverage(&vAccAverage) && accIsHealthy(&vAccAverage)) {
        applyAccError(&vAccAverage, &vError);
    }

However, that code does not get used with imu-f because we calculate the quaternion and pass it directly.