Re: [Paparazzi-devel] heading with AHRS_USE_GPS_HEADING but no GPS connected

[Felix Ruess]

Hi,

Of course the gyro data is integrated to give you attitude (including heading).... that's the whole point of these AHRS filters...

If you have neither magnetometer nor can use the course over ground of the GPS for heading, you don't have any absolute heading information (wrt. gegraphic north).

While in the short term the heading would be correct relative to the initial attitude, it will drift away over time.

Cheers, Felix

On Wed, Feb 12, 2014 at 8:10 AM, Kadir ÇİMENCİ <address@hidden> wrote:

very interesting case :)  A possible source for heading, came to my mind, is the integration of vertical gyro data but i don't think paparazzi project have implemented a method like this.. i am very curious about the solution ..

Kadir

2014-02-12 6:00 GMT+02:00 alonso acuña <address@hidden>:

Yes I am using ahrs int_cmpl_quat

On Tue, Feb 11, 2014 at 4:27 PM, Felix Ruess <address@hidden> wrote:

Hi Alonso,

what IMU driver and AHRS algorithm are you using?

Assuming you are e.g. using ahrs int_cmpl_quat, did you disable the magnetometer to use GPS heading instead (via <configure name="USE_MAGNETOMETER" value="FALSE"/>)?

If not, you should get a warning that you should probably disable the mag to use gps heading, as using both could have a bad effect if they don't give you the same heading....

Cheers, Felix

On Tue, Feb 11, 2014 at 8:36 AM, alonso acuña <address@hidden> wrote:

Hello. 

I have seen several interesting things:

 - somehow the heading is accurately calculated even when the GPS is not connected. I cannot understand where the heading value is coming from. 

- when the chip is powered up the heading is set to -BODY_TO_IMU_PSI instead of 0 as documented in the file

 

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