Class SemiAnalyticalKalmanEstimator


  • public class SemiAnalyticalKalmanEstimator
    extends AbstractKalmanEstimator
    Implementation of an Extended Semi-analytical Kalman Filter (ESKF) to perform orbit determination.

    The filter uses a DSSTPropagatorBuilder.

    The estimated parameters are driven by ParameterDriver objects. They are of 3 different types:

    1. Orbital parameters:The position and velocity of the spacecraft, or, more generally, its orbit.
      These parameters are retrieved from the reference trajectory propagator builder when the filter is initialized.
    2. Propagation parameters: Some parameters modelling physical processes (SRP or drag coefficients).
      They are also retrieved from the propagator builder during the initialization phase.
    3. Measurements parameters: Parameters related to measurements (station biases, positions etc...).
      They are passed down to the filter in its constructor.

    The Kalman filter implementation used is provided by the underlying mathematical library Hipparchus. All the variables seen by Hipparchus (states, covariances, measurement matrices...) are normalized using a specific scale for each estimated parameters or standard deviation noise for each measurement components.

    Since:
    11.1
    Author:
    Julie Bayard, Bryan Cazabonne, Maxime Journot
    See Also:
    "Folcik Z., Orbit Determination Using Modern Filters/Smoothers and Continuous Thrust Modeling, Master of Science Thesis, Department of Aeronautics and Astronautics, MIT, June, 2008.", "Cazabonne B., Bayard J., Journot M., and Cefola P. J., A Semi-analytical Approach for Orbit Determination based on Extended Kalman Filter, AAS Paper 21-614, AAS/AIAA Astrodynamics Specialist Conference, Big Sky, August 2021."
    • Constructor Detail

      • SemiAnalyticalKalmanEstimator

        public SemiAnalyticalKalmanEstimator​(MatrixDecomposer decomposer,
                                             DSSTPropagatorBuilder propagatorBuilder,
                                             CovarianceMatrixProvider covarianceMatrixProvider,
                                             ParameterDriversList estimatedMeasurementParameters,
                                             CovarianceMatrixProvider measurementProcessNoiseMatrix)
        Kalman filter estimator constructor (package private).
        Parameters:
        decomposer - decomposer to use for the correction phase
        propagatorBuilder - propagator builder used to evaluate the orbit.
        covarianceMatrixProvider - provider for process noise matrix
        estimatedMeasurementParameters - measurement parameters to estimate
        measurementProcessNoiseMatrix - provider for measurement process noise matrix
    • Method Detail

      • setObserver

        public void setObserver​(KalmanObserver observer)
        Set the observer.
        Parameters:
        observer - the observer
      • processMeasurements

        public DSSTPropagator processMeasurements​(List<ObservedMeasurement<?>> observedMeasurements)
        Process a single measurement.

        Update the filter with the new measurement by calling the estimate method.

        Parameters:
        observedMeasurements - the list of measurements to process
        Returns:
        estimated propagators