I'd like to see if I can help to get traditional heli simulation working. If I may impose, I'd like to get some general feedback from the community so that I can best direct my energy towards a solution.
Here's some background to help explain my motivations and abilities to contribute. I'm currently an undergraduate researcher in a non-linear controls research laboratory. My end goal is to use Fuzzy Logic to replace PID feedback control for an unmanned helicopter drone. I'm currently using a Thunder Tiger Raptor 90 as the testbed.
Of course, to test a new controller (especially on something as dangerous as a 90 series nitro), one must (ideally) have a working UAV platform first. In my search for a solution to the problems of finding ground station software, HIL, etc., I ran across Arducopter (much to my joy).
So now, instead of reinvinting more wheels than Goodyear, all I need to do to have a good testbed for my controllers is to help get HIL working for traditional helis in Arducopter, and add my own code replacing the PID control with fuzzy code.
The latter is something I'll likely do on my own, to submit for inclusion later (if anyone wants it). The former is something that I'd love to help with, but I'm not entirely sure where to start.
I'm currently the Robotics chair for our IEEE student chapter, so I could possibly contribute more than one set of person-hours to overcoming the challenges that are currently preventing HIL from working for traditional helis. I'm extremely interested in helping, and it's something I'd be willing to put a lot of hours into, simply because of how greatly it would assist me in accomplishing my own research goals.
So if you're currently working on HIL for traditional helis, or you know what's holding us back, gimmie something to shoot!
Do you know any aeronautical engineers? If so, you might be able to ask them about rotorcraft simulations, and if they know if they can adjust the simulation parameters.
But then again, the software they're using could be proprietary, as it usually is with commercial stuff...
The models can't be modified after they've been linearized, but they can be simply recreated using the original non-linear models, so long as the the simulator allows for different physics models to be applied. I know that you can plug your own model into FlightGear. I just don't know how to code the model.
The proprietary models are created based on information that's not hard to get. It's just a matter of linearizing the standard aerodynamics model around the operating parameters we're using. The hard part is finding all of those nonlinear equations, and manually going through the process of running all of those equations through Taylor expansion to get a linear model.
It's not too difficult. It's just a matter of going through the process.
The hard part (for me at least) is you then have to format the equations into a data set that actually forms a physics model that can be plugged into the simulator we're using. It's a little MATLAB, followed by a lot of coding.
If someone wants to do the coding, I can do the math side of things. I just don't know if we have someone in the code group that knows enough about coding for FlightGear to create a completely custom physics engine.
If we do, I'd love to work with them. I know the math on how to linearize the atmospheric model equations, and it wouldn't be hard to find the real non-linear equations and put together a transfer function. I just need someone that can code it into a real physics engine.