#2900 Heading Indicator tumbling: make g-node configurable

[Benedikt Hallinger]

• Followup on https://sourceforge.net/p/flightgear/codetickets/2840/
• See also discussion: https://forum.flightgear.org/viewtopic.php?f=14&t=42420

I think it may be useful if the aircraft dev could optionally specify a custom g node in heading_indicator_dg.cxx.

So this patch adds that.

instrumentation.xml:

<heading-indicator-dg>
...
    <limits>
        <g-node>/accelerations/pilot-gdamped</g-node>
        ...

will get the value from the alternate node. Default node remains untouched if not configured.

---

Code can be found in my branch heading_indicator_gnodeConf at https://beni.hallinger.org/git/flightgear.git

[Benedikt Hallinger]

While at it; I also added configurable heading-in and yaw-rate.
Especially the heading source may be useful for easily switching heading sources in complex planes.
And yaw-rate may be useful to implement custom aircraft error compensation technic.

<heading-indicator-dg>
...
   <heading-source>/orientation/heading-deg-TEST</heading-source>
    <limits>
        <g-node>/accelerations/pilot-gdamped</g-node>
        <yaw-rate-source>/orientation/yaw-rate-degps-TEST</yaw-rate-source>
        ...

[Benedikt Hallinger]

Tested with the c182 (and its /accelerations/pilot-gdamped node, and that seems to work better.

The alternative to this implementation is in my view to implement such a thing in c++ space.

The best thing would be imho, if the instrument had an internal (configurable) filter in c++ space, but could also source the value from some external/custom property (like the patch adds currently).

[Benedikt Hallinger]

Pushed another addition, implementing a (optional configurable) low pass filter.
it defaults to 10 currently, which allowed me hard landings without tumbling.

<heading-indicator-dg>
...
   <heading-source>/orientation/heading-deg-TEST</heading-source>
    <limits>
        <g-node>/accelerations/pilot-gdamped</g-node>
        <g-filter-time>10.0</g-filter-time>
        <yaw-rate-source>/orientation/yaw-rate-degps-TEST</yaw-rate-source>
        ...

The g-filter-time is changeable at runtime (limits subtree of the instrument instance)

[Benedikt Hallinger]

@jmturner I Think this should be ready.