Sensor Fusion Algorithm

mason_safavy

daylanKifky
Hello Bruno
Thanks again for responding,
After 2 weeks of testing the library and doing some good calibration,
Finally I found out the covariance matrices variables are causing the yaw drift.
As you are the only man who is helping so I decided to ask for help again.

these variables are killing me and my project, I will be grateful for anyhelp.
Kind Regards,
Mason

daylanKifky

Hi!
As I said, the adafruit library is heavily reworked, and many of these constants are not present in the original one (they are probably calculated somewhere else)

But in my experience it doesn't require tweaking of these types of values to get a decent result at the beginning. Instead I would double check that:

You are inputting the values of the Sensor in the correct order (I described the reordering from the LSM9DS1) in an answer above)
You are setting the correct sample rate to the Filter
The 3 sensors are properly calibrated and the calibration is being applied. In order to check this a good idea is to make a dump of the readings in CSV, and then plot the results, you should see:
- The calibrated gyro readings are ~ 0 + small noise when the sensor is static
- The calibrated accel readings are ~ 0 + small noise when the sensor is static, except for one axis that should be ~ 1g + noise. Try different orientations and check that the 1g axis changes accordingly
- The mag requires a little more work: you should move it around in all dimensions while you dump the values, then make a 3D scatterplot: you should see a sphere centered at the origin of the world

mason_safavy

daylanKifky
Thanks again for your attention.
I'm working on the covariance variables, all the problems are related to these variables, so far it going well for me.
I'm gonna let you know what exact setting should be used.

Regards
Mason

daylanKifky

Great!
Keep us informed, would love to know the setting that works for you!

mason_safavy

daylanKifky
Hi again,
After an incredible journey, finally I have acceptable output.
After realizing that the adafriut AHRS library is written for FXAS21002C, I started compare the noise values of LSM9DS1 and FXAS21002C. It's just 10 times the FXAS21002C, not that much 🙂
and multiplying the gyro values by 10, the results are kind of acceptable but it can be better.
I just wanna thank chordata and your community for supporting an outsider.

Best Regards.
Mason

mason_safavy

Hey Bruno,
I wanna appreciate all the previous things that you have done, and another huge appreciation for the possibility that you're making use only of the software side Chordata.
We're working on an open source project like you, and I'm just an honored member.
Wait for an introduction video from us which will be special for you.
can't wait to get my hands to the python script.
I forgot to say I'm a guy. 😆

Best Regards,
Mason

daylanKifky

Hello mason_safavy!
You are very welcome! and can't wait to see the intro video, thanks!

Once the python module is released we would really appreciate your feedback

daylanKifky

By the way if anyone is joining the discussion at this point: we talked about it and some developments related to it in this livestream. In particular we are quite exited about the possible applications of the new notochord as python module which will expose (among many other things) python endpoints to the Kalman filter we were talking about with @mason_safavy

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