[Jsbsim-devel] Converting JSBSim XML models to the new v2.0 config file format

[Jon B. <js...@ha...>]

As you know, JSBSim has been undergoing some major design upgrades including the
incorporation of a more robust XML parser and config  file format. This necessitates
converting older aircraft config files into the new format. That can be done by hand, but
is tedious. A facility has been added to the last release of "old" JSBSim (standalone
application) that converts an aircraft config file into the new format.

Getting or Building the Converter
---------------------------------

You can download a copy of the converter application executable for Cygwin from the JSBSim
web site here:

http://sourceforge.net/project/showfiles.php?group_id=19399

You can also do an anonymous check out of the code from CVS like this:

cvs -d:pserver:ano...@cv...:/cvsroot/jsbsim login

cvs -z3 -d:pserver:ano...@cv...:/cvsroot/jsbsim co -r HEAD_LEGACY_1
JSBSim

Then, cd to the JSBSim/ directory and type:

make -fMakefile.solo

Using the converter
-------------------

The converter is simply the JSBSim standalone application with added features. You run it
like normal, but add the "--convert" option:

./jsbsim --convert --aircraft=myaircraft

For example:

./jsbsim --convert --aircraft=T38

The aircraft to be converted must be in the aircraft/ directory under a directory with the
same name as the aircraft, as before.

Caveats
-------

This converter will not (at this time) convert engines, thrusters, scripts, or autopilots
(that are in separate files) to the new format. Engines, thrusters, and scripts must be
hand converted (it's not a big deal, really). Any autopilot definitions that are in a
separate file can be temporarily copied into the <autopilot> section of the main aircraft
config file. That should work. I haven't tried this yet. If that does not work, then copy
the autopilot into the <flight_control> section. After conversion, copy it back.

All files must now be properly formatted XML files.

Scripts have changed. To make them well-formed XML files you must now place a "/" at the
end of single element definitions:

The new way:

  <use aircraft="c172x"/>
  <use initialize="reset00"/>
  <run start="0.0" end="100" dt="0.00833333">
    <when>
      <parameter name="sim-time-sec" comparison="ge" value="0.25"/>
      <parameter name="sim-time-sec" comparison="le" value="1.00"/>
      <set name="fcs/throttle-cmd-norm" value="1.0" action="FG_RAMP" tc ="0.05"/>
      <set name="fcs/mixture-cmd-norm" value="0.55" action="FG_RAMP" tc ="0.05"/>
      <set name="propulsion/magneto_cmd" value="3"/>
      <set name="propulsion/starter_cmd" value="1"/>
    </when>
    ...

Notice also that

 type="FG_VALUE"
 action="FG_STEP"
 persistent="false"

are all now the default and do not need to be explicitly specified. Also, the tc (time
constant) is superfluous if the action is FG_STEP.

In the new format above, notice the "/" character at the end of the set, parameter, and
use lines.

Information on the new engine format and thrusters will be forthcoming in the new format
definition document. Until then, look at examples in the CVS repository for new aircraft
which have already been converted. Also, post any questions here.

Thanks,

Jon