I was investigating about the KAP140. I read the manual and the autopilot
documents of FlightGear and I think there may be some errors in the
KAP140.xml file.
I've arrived to that conclusion when I saw that the plain wasn't unable of
performing a 0-0 visibility approach with ILS.
I have improved the file (I think, I've never used a real Cessna 172 with
the KAP140, so I do not know if this result is more or less realistic):
- In the KAP140 manual there are a lot of references that indicates the
KAP140 uses elevator trim and not elevator for handling altitudes. So I have
adapted KAP140.xml file to use elevator trim. It results in softer altitude
changes and the autopilot does not conflict with joystick or yoke.
- I have changed some parameters trying to make Cessna 172 autopilot capable
of doing an ILS approach and landing without intervention of the user except
for throttle. This new configuration makes autopilot softer than previous.
Please, test it and include it in the CVS if you like it. Also I am
interested in the opinion of any pilot that has flown a real Cessna and
remembers the real autopilot performing.
--
Woodyst.
--- c172p.bkp/Systems/KAP140.xml 2006-12-28 01:33:06.000000000 +0100
+++ c172p/Systems/KAP140.xml 2007-01-03 02:35:55.000000000 +0100
@@ -62,7 +62,7 @@
<prop>/autopilot/KAP140/settings/target-intercept-angle</prop>
</output>
<config>
- <Kp>2.0</Kp> <!-- proportional gain -->
+ <Kp>3.0</Kp> <!-- proportional gain -->
<beta>1.0</beta> <!-- input value weighing factor -->
<alpha>0.1</alpha> <!-- low pass filter weighing factor -->
<gamma>0.0</gamma> <!-- input value weighing factor for -->
@@ -226,7 +226,7 @@
<gamma>0.0</gamma> <!-- input value weighing factor for -->
<!-- unfiltered derivative error -->
<Ti>15.0</Ti> <!-- integrator time -->
- <Td>0.0</Td> <!-- derivator time -->
+ <Td>0.000</Td> <!-- derivator time -->
<u_min>-0.001</u_min> <!-- minimum output clamp -->
<u_max>0.017</u_max> <!-- maximum output clamp -->
</config>
@@ -256,19 +256,19 @@
<prop>/autopilot/KAP140/settings/target-pressure-rate</prop>
</reference>
<output>
- <prop>/controls/flight/elevator</prop>
+ <prop>/controls/flight/elevator-trim</prop>
</output>
<config>
- <Kp>5.0</Kp> <!-- proportional gain -->
+ <Kp>7.0</Kp> <!-- proportional gain -->
<beta>1.0</beta> <!-- input value weighing factor -->
<alpha>0.1</alpha> <!-- low pass filter weighing factor -->
<gamma>0.0</gamma> <!-- input value weighing factor for -->
<!-- unfiltered derivative error -->
- <Ti>4.0</Ti> <!-- integrator time -->
+ <Ti>8.0</Ti> <!-- integrator time -->
<Td>0.0</Td> <!-- derivator time -->
- <u_min>-0.5</u_min> <!-- minimum output clamp -->
- <u_max>0.5</u_max> <!-- maximum output clamp -->
+ <u_min>-5</u_min> <!-- minimum output clamp -->
+ <u_max>5</u_max> <!-- maximum output clamp -->
</config>
</pid-controller>
-</PropertyList>
\ No hay ningún carácter de nueva línea al final del fichero
+</PropertyList>
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