On 9 Sep 2009, at 03:01, dave perry wrote:

> Sorry, I misunderstood you concerning the animation edits.  I will be
> glad to help with the xml edits and testing.  Getting rid of the
> spurious 5x for the glide scope and adding the clamps is a good idea  
> and
> adding the normalized CDI and GS could make the animators job  
> easier.  I
> will start by changing the vor.xml and vor2.xml in Instruments-3D that
> are used in the pa24 and pa28 and perhaps several other AC.

I've already changed various aircraft locally, for testing:

        - the generic 2D and 3D instruments
        - the Seneca, B1900d, 747-400, C172P and Aerostar
        - the Primus-1000 suite

I don't claim to have done this 100% correctly yet - especially, I  
need to convince myself the that GS-ARM modes of the various  
autopilots (eg, the KAP-140 in the default C172) are behaving  
correctly, since this is generally implemented as Nasal scripts  
testing the GS needle deflection.

One area I do need help with is the autopilot PID laws: eg, here's the  
relevant chunk for the B1900d:

<pid-controller>
        <name>Glideslop Hold</name>
        <input>
                <prop>instrumentation/nav/gs-needle-deflection-norm</prop>
        </input>
        <reference>
                <value>0</value>
        </reference>
        <output>
                <prop>autopilot/settings/target-pitch-deg</prop>
        </output>
        <config>
                <Kp>-1.5</Kp>
                <beta>1.0</beta>
                <alpha>0.1</alpha>
                <gamma>0.0</gamma>
                <Ti>10.0</Ti>
                <Td>0.0</Td>
                <u_min>
                        <value>-10</value>
                </u_min>
                <u_max>
                        <value>5</value>
                </u_max>
        </config>
</pid-controller>

Since I've switched the input to be the normalised prop, we've gone  
from a unclamped input (swinging from sometimes -60 to 60!) to one  
which is much 'smaller' in magnitude and clamped to [-1 .. 1]. I  
*guess* the fix will be to increase the gain on the PID, otherwise GS  
hold will tend to lag, but that's about the total of my knowledge of  
tweaking the PIDs.


James

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