Maximal count exceeded error problem

[alberto-ferrero]

Hi Suleyman
It might not be related to your problem but I would like to share just my experience working with the BLS orbit estimator.

I was comparing results from some TM GPS data, evaluating the orbit using Orekit BLS and GMAT BLS.

I implemented what discussed in this thread:

Complete OD using ITRF

Hi @jlipinski, Welcome to the Orekit community ! Currently I don’t think there is a way to use IODGibbs with a non inertial frame. So converting your PV in ITRF to an inertial frame like GCRF is the proper way to do it. I think it would be hard to write the IOD method so they can use non inertial frames. I’m not sure the time required to develop it would be worth it, since a simple frame conversion can do the trick. Yes, or maybe circular orbit. What does your orbit look like, is it a cir…

Anyhow, for big dataset of TM data (so I suppose it is your case), I was facing either really bad results, either your convergence issues.

I just realized that I was not adding any perturbations to the Numerical Propagator used to orbit estimation.

    //Build numerical propagator
    DormandPrince853IntegratorBuilder integratorBuilder = new DormandPrince853IntegratorBuilder(
        minIntegrationStep, maxIntegrationStepM, positionTolerance);
    NumericalPropagatorBuilder propagatorBuilder = new NumericalPropagatorBuilder(iodCartesian,
        integratorBuilder,
        PositionAngle.TRUE,
        positionScale);
    PerturbationModel.addGravityFieldPerturbation(propagatorBuilder);
    PerturbationModel.addThirdBodyPerturbation(propagatorBuilder);
    PerturbationModel.addOceanTidesPerturbation(propagatorBuilder);

where

public static void addGravityFieldPerturbation(NumericalPropagatorBuilder propagatorBuilder) {
    //Add Gravity field
    val provider = GravityFieldFactory.getNormalizedProvider(Constants.harmonicDegree, Constants.harmonicOrder);
    val gravityFieldForce = new HolmesFeatherstoneAttractionModel(Constants.earthShapeIERS.getBodyFrame(), provider);
    propagatorBuilder.addForceModel(gravityFieldForce);
  }

  public static void addThirdBodyPerturbation(NumericalPropagatorBuilder propagatorBuilder) {
    // Third Bodies
    ThirdBodyAttraction thirdBodyMoon = new ThirdBodyAttraction(CelestialBodyFactory.getMoon());
    ThirdBodyAttraction thirdBodySun = new ThirdBodyAttraction(CelestialBodyFactory.getSun());
    propagatorBuilder.addForceModel(thirdBodyMoon);
    propagatorBuilder.addForceModel(thirdBodySun);
  }

  public static void addOceanTidesPerturbation(NumericalPropagatorBuilder propagatorBuilder) {
    val provider = GravityFieldFactory.getNormalizedProvider(Constants.harmonicDegree, Constants.harmonicOrder);
    val oceanTides = new OceanTides(Constants.earthShapeIERS.getBodyFrame(),
        provider.getAe(), provider.getMu(), 1, 1, IERSConventions.IERS_2010,
        TimeScalesFactory.getUT1(IERSConventions.IERS_2010, true));
    propagatorBuilder.addForceModel(oceanTides);
  }

Especially for longer window, I guess, without the correct perturbation model, the estimation fails as the numerical propagator cannot match the data (real) you have.
Could it make sense?

Alberto