Package org.orekit.propagation.semianalytical.dsst

Class DSSTHarvester

java.lang.Object
org.orekit.propagation.AbstractMatricesHarvester
org.orekit.propagation.semianalytical.dsst.DSSTHarvester
All Implemented Interfaces:
MatricesHarvester
public class DSSTHarvester extends AbstractMatricesHarvester
Harvester between two-dimensional Jacobian matrices and one-dimensional additional state arrays.
Since:
11.1
Author:
Luc Maisonobe, Bryan Cazabonne

  • Method Details

    • getStateTransitionMatrix

      public RealMatrix getStateTransitionMatrix(SpacecraftState state)
      Extract state transition matrix from state.

      Some propagators use an orbit type B as the propagator builder parameter, and a different type Y for the propagated orbit. Typical examples are TLE or specialized GNSS propagators that use Keplerian-like builder parameters but produce Cartesian states. This method is not aware of such parameters change, so it always computes dY/dY₀ with the same representation for the current propagated state Y and the initial state Y₀.

      In order to compute dY/dB₀ where the current propagated state Y and the initial building state B₀ have different types, one should compute dY/dB₀ = dY/dY₀ dY₀/dB₀, where the first factor dY/dY₀ is given by this method and the second factor dY₀/dB₀ is given by the method MatricesHarvester.getStateJacobianVsBuilderParameters(SpacecraftState).

      Parameters:
      state - spacecraft state
      Returns:
      state transition matrix, with semantics consistent with propagation, or null if no state transition matrix is available orbit type.

    • getParametersJacobian

      public RealMatrix getParametersJacobian(SpacecraftState state)
      Get the Jacobian with respect to propagation parameters.
      Parameters:
      state - spacecraft state
      Returns:
      Jacobian with respect to propagation parameters, or null if there are no parameters

    • getB1

      public RealMatrix getB1()
      Get the Jacobian matrix B1 (B1 = ∂εη/∂Y).

      B1 represents the partial derivatives of the short period motion with respect to the mean equinoctial elements.

      Returns:
      the B1 jacobian matrix

    • getB2

      public RealMatrix getB2(SpacecraftState state)
      Get the Jacobian matrix B2 (B2 = ∂Y/∂Y₀).

      B2 represents the partial derivatives of the mean equinoctial elements with respect to the initial ones.

      Parameters:
      state - spacecraft state
      Returns:
      the B2 jacobian matrix

    • getB3

      public RealMatrix getB3(SpacecraftState state)
      Get the Jacobian matrix B3 (B3 = ∂Y/∂P).

      B3 represents the partial derivatives of the mean equinoctial elements with respect to the estimated propagation parameters.

      Parameters:
      state - spacecraft state
      Returns:
      the B3 jacobian matrix

    • getB4

      public RealMatrix getB4()
      Get the Jacobian matrix B4 (B4 = ∂εη/∂c).

      B4 represents the partial derivatives of the short period motion with respect to the estimated propagation parameters.

      Returns:
      the B4 jacobian matrix

    • freezeColumnsNames

      public void freezeColumnsNames()
      Freeze the names of the Jacobian columns.

      This method is called when proagation starts, i.e. when configuration is completed

      Specified by:
      freezeColumnsNames in class AbstractMatricesHarvester

    • getJacobiansColumnsNames

      public List<String> getJacobiansColumnsNames()
      Get the names of the parameters in the matrix returned by MatricesHarvester.getParametersJacobian(org.orekit.propagation.SpacecraftState).

      Beware that the names of the parameters are fully known only once all force models have been set up and their parameters properly selected. Applications that retrieve the matrices harvester first and select the force model parameters to retrieve afterwards (but obviously before starting propagation) must take care to wait until the parameters have been set up before they call this method. Calling the method too early would return wrong results.

      The names are returned in the Jacobians matrix columns order

      Returns:
      names of the parameters (i.e. columns) of the Jacobian matrix

    • initializeFieldShortPeriodTerms

      public void initializeFieldShortPeriodTerms(SpacecraftState reference)
      Initialize the short periodic terms for the "field" elements.
      Parameters:
      reference - current mean spacecraft state

    • initializeFieldShortPeriodTerms

      public void initializeFieldShortPeriodTerms(SpacecraftState reference, PropagationType type)
      Initialize the short periodic terms for the "field" elements.
      Parameters:
      reference - current mean spacecraft state
      type - MEAN or OSCULATING

    • updateFieldShortPeriodTerms

      public void updateFieldShortPeriodTerms(SpacecraftState reference)
      Update the short periodic terms for the "field" elements.
      Parameters:
      reference - current mean spacecraft state

    • setReferenceState

      public void setReferenceState(SpacecraftState reference)
      Set up reference state.

      This method is called whenever the global propagation reference state changes. This corresponds to the start of propagation in batch least squares orbit determination or at prediction step for each measurement in Kalman filtering. Its goal is to allow the harvester to compute some internal data. Analytical models like TLE use it to compute analytical derivatives, semi-analytical models like DSST use it to compute short periodic terms, numerical models do not use it at all.

      Specified by:
      setReferenceState in interface MatricesHarvester
      Overrides:
      setReferenceState in class AbstractMatricesHarvester
      Parameters:
      reference - reference state to set

    • getOrbitType

      public OrbitType getOrbitType()
      Get the orbit type used for the matrix computation.
      Returns:
      the orbit type used for the matrix computation

    • getPositionAngleType

      public PositionAngleType getPositionAngleType()
      Get the position angle used for the matrix computation.

      Irrelevant if MatricesHarvester.getOrbitType() returns OrbitType.CARTESIAN.

      Returns:
      the position angle used for the matrix computation