Subsystem/ahrs
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AHRS subsystem
The AHRS subsystem specifies which attitude estimation filter you are using.
e.g. for the complementary filter:
| File: conf/airframes/myplane.xml |
<firmware name="fixedwing or rotorcraft">
...
<subsystem name="ahrs" type="int_cmpl_euler"/>
</firmware>
|
There is a test program ( sw/airborne/test/ahrs/compare_ahrs.py ) to compare different AHRS implementations on simple test cases.
Complementary Euler (fixed point)
Complementary Quaternion (fixed point)
For the latest integer complementary quaternion filter (int_cmpl_quat):
| File: conf/airframes/myplane.xml |
<firmware name="rotorcraft">
...
<subsystem name="ahrs" type="int_cmpl_quat"/>
</firmware>
<section name="AHRS" prefix="AHRS_">
<define name="PROPAGATE_FREQUENCY" value="512"/>
<define name="H_X" value=" 0.51562740288882"/>
<define name="H_Y" value="-0.05707735220832"/>
<define name="H_Z" value=" 0.85490967783446"/>
</section>
|
H is the normalised local magnetic field which can be derived by following instructions on the IMU calibration page here.
Other flags of interest are;
- AHRS_PROPAGATE_LOW_PASS_RATES : apply a low pass filter on rotational velocity
- AHRS_MAG_UPDATE_YAW_ONLY : use mag to update yaw only