Flight gear and Simulink

[Guest Tbird12]

I am working on a project using a Matlab/simulink 6 DOF aircraft model interfaced with Flightgear. I am having trouble with getting my model to land accuratly in Flight Gear. My model detects the ground but it does not correlate with the altitude in FLight Gear. Has anyone done landing and takeoff simulation using matlab/simulink and flight gear before?

[Guest fatty]

This would probably be a good question to send to the Flightgear-Devel mailing list, which is at [email protected]. I don't know what the problem is, but chances are one of the developers could help you.

[Guest jstevenson]

The short answer is YES - I am using a Simulink model (using AeroSIM) to simulate a landing of an aircraft, and using FlightGear to visualize. I too noticed the descrepancy in FlightGear versus the altitude I saw in AeroSIM/Matlab. Here's the scoop:The thing called "altitude" in AeroSIM is the altitude based on the EGS96 "ellipsoid earth model". For the area of the world where I was flying (around Clarenville, Newfoundland) I found that this was approximately -8m off (i.e. too low) the altitude above Mean Sea level, which I understand is based on the WGS84 Earth model. I found this later altitude to match perfectly with what FlightGear is also using for it's ground terrain mesh. I've switched over to using MSL in my AeroSIM model to match up with FG, so at least my aircraft "looks" like it's actually sitting on the ground!BTW - you can monitor the internal FG variable called /position/ground-elev-m[0] which you'll see matches the MSL variable in AeroSIM (or any other WGS84-based aeorsim) very well.I'm currently inverstigating if there is a way to send FG variable information BACK to MATLAB. There's got to be a way!-Jon