Hi @benoist
What you’ve done is probably correct. Your problem comes from a missing feature in Orekit. Indeed, it’s not currently possible to use PartialDerivatesEquations class with a SpacecraftState built from AbsPVCoodinates.
We will add in the next version of Orekit (i.e. 10.2) a new feature allowing to use PartialDerivativesEquations class with a SpacecraftState built from AbsPVCoordinated. Probably, it will be a new class. Something like AbsPartialDerivativesEquations. This feature is currently available on Vincent Mouraux’s Orekit projet (on its cr3bp branch). It will be soon added to the main Orekit project.
What you can try in the meantime, is to use DerivativeStructure features of Orekit. If you want an example on how to use it, you can have a look on MaximeJ’s post here. In its post, he gives a small scrip explaining how to compute a Jacobian Matrix using DerivativeStructure features. You have just to use AbsPVCoordinates instead of Orbit to build your SpacecraftState.
Kind regards,
Bryan