RE: [Jsbsim-devel] Matlab-JSBSim Interface

[Philippose R. <sa...@ro...>]

Hi again Jon,
  Just back from the lesson...it was a theory lesson
today...driving is happening tomorrow :-) And the
weather...it was +7deg C today...and blue skies...so I
dont expect to be fighting ice (that would be too much
for me who still looks on the left hand side for the
gear lever :-)!)

> Good work!

  Thanks for the acknowledgement :-)! 

>I have thought about this. So, instead of sending
data >over a socket 
>like
>this:
>
>set fcs/elevator-cmd-norm 0.03
>set fcs/rudder-cmd-norm 0.00
>...

>you could do this:
>
>0.03, 0.00 ...
>
>The spec would be:
>
><input port="port#">
>  <property>fcs/elevator-cmd-norm</property>
>  <property>fcs/rudder-cmd-norm</property>
></input>
>
>To avoid the endian issue, I'd still probably do the
>data transfer 
>using
>character strings, unless that's a really bad idea
for >some reason I'm 
>not
>yet aware of. I guess that would require your
>Matlab/Simulink side to
>convert the data, first. It may also then require a
>precision attribute 
>in
>the spec:
>
><input port="port#">
>  <property
>precision="##.####">fcs/elevator-cmd-norm</property>
>

  I totally agree with you on this...I had considered
sending it as a delimited character string...because
that way...as you said...no worries about precision,
and also, it can be done using one send operation.

  I dont foresee the conversion in Simulink to be a
problem.

  In fact, the XML specification method seems perfect.
Is it too much work to do a modification like that? 

  But then, at the same time, you also need to have
something like the telnet server running too, in order
to be able to suspend and resume simulation
  
>Fixed timestep. For the moment - given the recent
>changes to fix the 
>landing
>gear jitter problem - that fixed frame rate should be
>120 Hz.

  Thats great...so thats one problem of
synchronisation solved...as in...variable time step
solvers are always a pain to handle :-)!

>It might be possible to supply a stepping command in
>the input socket
>interface:
>
>step
>
>-or-
>
>step 2
>
>Would that be helpful? I don't think it would be too
>hard to provide a 
>step
>function that would allow a single step to be made or
a >number of 
>specified
>steps.

  I was thinking more in terms of something like the
first value in the character string sent out from
Simulink being a time value which would correspond to
the simulation time in Simulink...that way...JSBSim
would run at any step size specified by Simulink, and
will also always be in sync.

  But I think this is something that needs more
thought...so, I think we should leave it out for the
time being, and address it again later once everything
else is in place.

  There is one more thing I would like to discuss with
you about regarding the sockets in JSBSim, but shall
keep it to tomorrow :-)!

   Have a great evening!

Regards,

Philippose


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