Support estimation of spacecraft coefficient of reflectivity and drag #350
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Still need to add the option to not estimate it, and run more verification
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ChristopherRabotin
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Summary
This change enables the estimation of Cr and Cd in the orbit determination of Nyx. This change has long been coming.
The SRP estimation model is finicky. You will NEED to enable some level of state noise compensation. The ODTK MathSpec (page 179) recommends modeling the SRP as a first order Gauss Markov process, which accounts for the time between measurements to even out the partial of the Cr. Instead, Nyx estimates Cr directly, assuming that it is a fixed value. This means that the filter is very (too?) responsive to changes in Cr. Too much SNC, and the Cr estimation does not happen because the changes are absorbed by the SNC, and too little, and you'll end up with a very slow estimation, and a Cr value that fluctuates a lot.
Architectural Changes
Implementations of
ForceModelnow return a rectangular Matrix where the extra data corresponds to the partial of that parameter (expected in the estimated state) wrt the velocity components.New Features
No change
Improvements
No change
Bug Fixes
No change
Testing and validation
Add the
od_val_sc_srp_estimationtest case. In this test case, tracking data is simulated for a GTO with a Cr of1.123, over 5 orbital periods (or 2 d 5 h). The initial estimation state is the same as the original one, but the Cr value is 1.5. The purpose of this test is to ensure that the estimated Cr converges onto the one from the tracking data.Documentation
This PR does not primarily deal with documentation changes.