Is there a simplified / reduced-fidelity model or method to accelerate dynamics calculations in RL?

[dw95kim]

Hello, I am using the JSBSim dynamics model in an RL project.

Here is the skeleton code I currently use:

jsbsim_exec = jsbsim.FGFDMExec()
jsbsim_exec.run_ic()
jsbsim_exec.run()

For my project, I would like to use a simplified or reduced-fidelity dynamics model to improve simulation speed.
However, I could not find any documentation or examples about simplified models on the official website.

So, how can I use a simplified dynamics model in JSBSim from Python?
Is there an existing method, or should I create a custom reduced-fidelity aircraft configuration?

Thank you.

[seanmcleod70]

It's not 100% clear what sort of simplification you're looking for.

For example one option in terms of a reduced-fidelity dynamics model is to assume a flat, non-rotating earth model with constant gravity etc. compared to what JSBSim models in terms of a rotating ellipsoid model etc. JSBSim doesn't offer a mechanism to downgrade/simplify to only running the calculations needed for a flat, non-rotating earth model.

The other option in terms of a reduced-fidelity dynamics model is to have a simplified and smaller subset of the aerodynamic model since there will be fewer calculations per time-step to calculate the set of forces and moments. I'd be interested to see a benchmark comparison to see how much of a difference this could make.

[dw95kim]

regarding the simplified aerodynamic model, do I need to manually reduce the parameters in aircraft.xml, or is there a built-in option in JSBSim for that?

[seanmcleod70]

You need to manually perform the simplification. JSBSim has no built-in knowledge of what forces and moments you're defining and how to go about simplifying them.