Sensor Fusion: Mag calibration disables Gyro axis

Hi there.. thanks for coming to the forums. Exciting news! we’re now in the process of moving to our new forum platform that will offer better functionality and is contained within the main Dialog website. All posts and accounts have been migrated. We’re now accepting traffic on the new forum only - please POST any new threads at//www.xmece.com/support. We’ll be fixing bugs / optimising the searching and tagging over the coming days.
4 posts / 0 new
Last post
Wed, 2020-06-17 11:27
#1
gme_johannes
Offline
Last seen:3 days 9 hours ago
Joined:2017-12-22 10:09
Sensor Fusion: Mag calibration disables Gyro axis

Hello Dialog support,

对于我们的项目我改编DA14585_IOTP SDK。在stead of ICM42605 I use BMI160, instead of AK09915 I use BMM150 (so, same sensors as in the old DA14583 development kit). I successfully modified SDK6, raw data readout seems to be working fine for all sensors.

I have modified the axes' orientation in user_sfl_util.c according to the datasheets.

At the start, the magnetometer raw data looks fine, but the "compass" overlay is wrong. As soon as I run the magnetometer calibration, the compass overlay is okay.

However now I notice that one of the 3 gyroscop axes suddenly is very strongly attenuated! How can this be?

BR Johannes

Device:
DA14585
Thu, 2020-06-18 12:08
PM_Dialog
Offline
Last seen:7 hours 10 min ago
Staff
Joined:2018-02-08 11:03
Hi gme_johannes,

Hi gme_johannes,

Since it is a custom design and custom code, to be honest I am not completely sure about what the problem might be. This is little bit generic and depends on your application. The 585 MSK DK is supported as it is provided. Probably you might check the sensor calibration again. Are you able to replicate it with the 585 MSK DK?

Thanks, PM_Dialog

Thu, 2020-06-18 18:09
gme_johannes
Offline
Last seen:3 days 9 hours ago
Joined:2017-12-22 10:09
Hi PM,

Hi PM,

I believe my problem to be the interface to the Fusion library, which itself is not open source - but I would like to continue using it in our project.

The BMM150 data has as resolution of 1µT/LSB (after hall resistor corrections) while the AK09915 has ~0.15µT/LSB. This is also well visible in the raw data. Should I scale it before feeding it to the fusion library?

Do you have documentation for the Fusion Library, apart from what I can find in the application notes of the DA14585 MS IoT DK? I would like to understand how the magnetometer calibration can affect the gyroscope raw data. If you do not have any further docs, then I will try to solve the problem on my own an report back.

BR Johannes

Fri, 2020-06-19 14:58
PM_Dialog
Offline
Last seen:7 hours 10 min ago
Staff
Joined:2018-02-08 11:03
Hi gme_johannes,

Hi gme_johannes,

Thanks for getting back to me, but unfortunately there isn’t any specific document describing how to use the fusion library. All information you need in order to use the DK is in the user guide.

Thanks, PM_Dialog