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Re: [Paparazzi-devel] Plane changing direction in GCS

From: Felix Ruess
Subject: Re: [Paparazzi-devel] Plane changing direction in GCS
Date: Sat, 25 Jul 2015 19:31:57 +0200


did you check if you get proper readings from the mag?

The IMU_MAG (float) and IMU_MAG_SCALED (int) messages give you the mag readings using the mag calibration and current calibration.

Also keep in mind that the "current calibration" is a simple linear approximation of a changing offset due to current flowing nearby, so without running motor it should be the same as without current calibration.

Your mag neutrals seem a bit high (but of course depends what you have placed close to the mag...
I would suggest redoing the mag calibration (and use the plot option of the script to see if the final fit makes sense and you have nicely distributed measurement points).

This is assuming that you have set your local magnetic field correctly

Cheers, Felix

On Fri, Jul 24, 2015 at 11:38 PM, rijesh <address@hidden> wrote:
So I did some further testing again today and I think i may still have some issues.

If I set the USE MAGNETOMETER flag to TRUE, then the icon(psi value) will return back to the direction it was initialized at. Also if I initialize it with the board pointing north the psi value I read is 169 degrees, if I initialize when pointing west the psi value I read be with a few degrees of 169 degrees. Yet I can rotate the board and watch as the icon makes a full smooth 360 degree rotation.

If I set it to FALSE and AHRS USE GPS HEADING to TRUE the plane icon will initialize to 90 degrees. The icon rotates normally when I rotate the board but has the incorrect direction since the board always initializes to 90degrees on start up no matter the initial orientation. I'm assuming this won't be an issue in flight as the GPS has speed and can be used for direction.

I would really like to get magnetic orientation, primarily in high winds where a lot of strafing can occur.

How can I get an accurate Mag Heading that is completely independent of GPS?

Also is the IMU MAG message in messages after applying current calibration, magnetic deviation and magnetic variation?

A similar issue was brought up before,


On Thu, Jul 23, 2015 at 7:57 PM, rijesh [via Paparazzi UAV] <[hidden email]> wrote:
Thanks Felix,
Everything seems to be working fine for me. I was running a version of v5.4 that may have been incorrectly merged. I thinking that could have been the cause of my trouble.

Anyway the Use Magnetometer flag seems to be working now and I am getting the desired results.

Thanks again for the time and support!

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