Another hint:
If the AHRS does not properly support body_to_imu and you don't want to
add an upside down option to the imu, you can also simply invert the
signs on the y and z axis:
<section name="IMU" prefix="IMU_">
<define name="GYRO_Q_SIGN" value="1"/>
<define name="GYRO_Q_SIGN" value="-1"/>
<define name="GYRO_R_SIGN" value="-1"/>
<define name="GYRO_Q_SIGN" value="-1"/>
<define name="ACCEL_X_SIGN" value="1"/>
<define name="ACCEL_Y_SIGN" value="-1"/>
<define name="ACCEL_Z_SIGN" value="-1"/>
....
</section>
Cheers, Felix
On Mon, Sep 8, 2014 at 5:18 PM, Felix Ruess <address@hidden
<mailto:address@hidden>> wrote:
Hi again,
or do something like adding an APOGEE_UPSIDE_DOWN option:
https://github.com/flixr/paparazzi/commit/58e6cf78f69eb6e49501a5774513cc0abf2c3e06
Cheers, Felix
On Mon, Sep 8, 2014 at 5:08 PM, Felix Ruess <address@hidden
<mailto:address@hidden>> wrote:
Hi Andreas,
if you only want to turn it upside down (keeping the x-axis to
the front), just turn it 180deg around the x-axis:
<define name="BODY_TO_IMU_PHI" value="180" unit="deg"/>
<define name="BODY_TO_IMU_THETA" value="0" unit="deg"/>
<define name="BODY_TO_IMU_PSI" value="0" unit="deg"/>
But please not that not all AHRS algorithms properly take this
into account: https://wiki.paparazziuav.org/wiki/Subsystem/ahrs
Which one are you using?
Cheers, Felix
On Mon, Sep 8, 2014 at 5:01 PM, Andreas Philipp
<address@hidden
<mailto:address@hidden>> wrote:
Dear list,
in order to mount an AP reversed (upside down, for accessing
the plugs
easily), what do I have to change in the airframe file? I
couldn't find
any hint in the archive or wiki.
For an Apogee I changed this:
<section name="IMU" prefix="IMU_">
<!-- Calibration Neutral -->
<define name="GYRO_P_NEUTRAL" value="0"/>
<define name="GYRO_Q_NEUTRAL" value="0"/>
<define name="GYRO_R_NEUTRAL" value="0 "/>
<define name="ACCEL_X_NEUTRAL" value="0"/>
<define name="ACCEL_Y_NEUTRAL" value="0"/>
<define name="ACCEL_Z_NEUTRAL" value="0"/>
<define name="BODY_TO_IMU_PHI" value="0" unit="deg"/>
<define name="BODY_TO_IMU_THETA" value="0" unit="deg"/>
<define name="BODY_TO_IMU_PSI" value="0" unit="deg"/>
</section>
to that (just changing BODY_TO_IMU_THETA and BODY_TO_IMU_PSI):
<section name="IMU" prefix="IMU_">
<!-- Calibration Neutral -->
<define name="GYRO_P_NEUTRAL" value="0"/>
<define name="GYRO_Q_NEUTRAL" value="0"/>
<define name="GYRO_R_NEUTRAL" value="0 "/>
<define name="ACCEL_X_NEUTRAL" value="0"/>
<define name="ACCEL_Y_NEUTRAL" value="0"/>
<define name="ACCEL_Z_NEUTRAL" value="0"/>
<define name="BODY_TO_IMU_PHI" value="0" unit="deg"/>
<define name="BODY_TO_IMU_THETA" value="180" unit="deg"/>
<define name="BODY_TO_IMU_PSI" value="180" unit="deg"/>
</section>
This works in principle, however, the GCS (PFD) shows that
the AP is
initated reversed first and then needs a long time for
slowly drifting
to the correct position (actually it drifts beyond the right
roll
position and then back like controlled by a low-pass filter).
And maybe associated with this: When flying circles in the
flightplan,
the plane of the circle is tilted about several meters (may
be 20m or
more), leading to one side of the circle being lower than
the other,
which is strange and annoying for climate measurements. The
tilt is
always in the same direction.
What am I missing?
Thanks for any reply,
Andreas