MPU9250, mag not working, gyro wrong scale

lis-epfl / MAVRIC_Library

Software library to build drone autopilots

http://lis-epfl.github.io/MAVRIC_Library/

BSD 3-Clause "New" or "Revised" License

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Open jlecoeur opened 8 years ago

jlecoeur commented 8 years ago

I saw two issues with the MPU9250:

After a few seconds, the magnetometer is not updated. Its value is either constantly [0, 0, 0] or the last read value. This prevents flying without motion tracking system, @GregoireH did you have the same issue?
The scale of the gyroscope does not look right. When turning the drone by hand at approx 90°/s, the reading is 3.3rad/s which is around 180°/s. @jeanfrancoisburnier you checked gyroscope scales, have you noticed this before?

(branch mobrob_sparkyv2)

jlecoeur commented 8 years ago

edit: units

jlecoeur commented 8 years ago

I did some tests regarding gyro scale. I think the chip is not configured properly.

First I multiplied by 2 gyroscale and obtained correct scale with gyro_range = GYRO_500_DEG; Then I configured the module with

jlecoeur commented 8 years ago

Quick fixes until we solve the issue in the driver:

In #326 there is a hack to fix the gyro scale, but it only works for the default config gyro_range = GYRO_500_DEG;.
The magnetometer can be disabled in the attitude filter by commenting the call to update_step_mag(); in Ahrs_ekf::update() here ahrs_ekf.cpp#L425