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stabilization quat_int IERROR scale fix #1205

Merged
merged 1 commit into from
Jul 6, 2015
Merged

stabilization quat_int IERROR scale fix #1205

merged 1 commit into from
Jul 6, 2015

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flixr
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@flixr flixr commented Jun 10, 2015

This should (tm) result in less of a quantization error for the integral part (less static offset).
Reduce the GAIN_PRESCALER_I accordingly so that the gains set in the airframe file keep same scale.

While here also simplify the fb command prescalers/scaling...

@flixr flixr added this to the v5.6 milestone Jun 24, 2015
@flixr flixr force-pushed the stab_int_quat_prescalers branch from 6bac782 to a4ab590 Compare June 26, 2015 20:40
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flixr commented Jun 26, 2015

Only tested this in NPS, it should be correct.
@gautierhattenberger would be great if you could cross check the prescalers...

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On the IGAIN, the sum_err was divided by1024, then multiplied by 48 and divided 2, so if you have 1024 as input, output is : 1024* (1/1024)*48*(1/2) = 24.
Now you have a division by 128, then multiply by 4, so for the same input you have: 1024*(1/128)*4 = 32.
If I'm correct, by multiplying by 3 instead of 4, you should have the same final value than before.

@flixr
[rotorcraft] stabilization quat_int IERROR scale fix
6a99ae4 
This should (tm) result in less of a quantization error for the integral part (less static offset).
Reduce the GAIN_PRESCALER_I accordingly so that the gains set in the airframe file keep same scale.

While here also simplify the fb command prescalers/scaling...
@flixr flixr force-pushed the stab_int_quat_prescalers branch from a4ab590 to 6a99ae4 Compare June 30, 2015 21:44
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flixr commented Jun 30, 2015

Correct, thanks for checking again :-)
Amended the commit...
I guess should we also increase the INTEGRATOR_BOUND according to the new IERROR_SCALE?
That is assuming it had a meaningful value before...

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I guess so. It seems it should be 8 times bigger

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flixr commented Jul 4, 2015

Actually I think it makes sense to keep the limit, which would translate to just under 180deg (in float representation of the quat int) if would look at it like this...

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I never pay much attention to the sum_err value, but if you think it is already high enough, I'm fine.

flixr added a commit that referenced this pull request Jul 6, 2015
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Merge pull request #1205 from flixr/stab_int_quat_prescalers
c389e0c 
stabilization quat_int IERROR scale fix

This should (tm) result in less of a quantization error for the integral part (less static offset).
Reduce the GAIN_PRESCALER_I accordingly so that the gains set in the airframe file keep same scale.

While here also simplify the fb command prescalers/scaling...
@flixr flixr merged commit c389e0c into paparazzi:master Jul 6, 2015
@flixr flixr deleted the stab_int_quat_prescalers branch July 6, 2015 22:02
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