TLEPropagatorBuilder.java
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package org.orekit.propagation.conversion;
import java.util.List;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.attitudes.FrameAlignedProvider;
import org.orekit.data.DataContext;
import org.orekit.estimation.leastsquares.AbstractBatchLSModel;
import org.orekit.estimation.leastsquares.BatchLSModel;
import org.orekit.estimation.leastsquares.ModelObserver;
import org.orekit.estimation.measurements.ObservedMeasurement;
import org.orekit.frames.Frame;
import org.orekit.orbits.Orbit;
import org.orekit.orbits.PositionAngleType;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.analytical.tle.TLE;
import org.orekit.propagation.analytical.tle.TLEPropagator;
import org.orekit.propagation.analytical.tle.generation.TleGenerationAlgorithm;
import org.orekit.utils.ParameterDriver;
import org.orekit.utils.ParameterDriversList;
/** Builder for TLEPropagator.
* @author Pascal Parraud
* @author Thomas Paulet
* @since 6.0
*/
public class TLEPropagatorBuilder extends AbstractPropagatorBuilder {
/** Data context used to access frames and time scales. */
private final DataContext dataContext;
/** Template TLE. */
private final TLE templateTLE;
/** TLE generation algorithm. */
private final TleGenerationAlgorithm generationAlgorithm;
/** Build a new instance. This constructor uses the {@link DataContext#getDefault()
* default data context}.
* <p>
* The template TLE is used as a model to {@link
* #createInitialOrbit() create initial orbit}. It defines the
* inertial frame, the central attraction coefficient, orbit type, satellite number,
* classification, .... and is also used together with the {@code positionScale} to
* convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
* parameters used by the callers of this builder to the real orbital parameters.
* </p>
* @param templateTLE reference TLE from which real orbits will be built
* @param positionAngleType position angle type to use
* @param positionScale scaling factor used for orbital parameters normalization
* (typically set to the expected standard deviation of the position)
* @param generationAlgorithm TLE generation algorithm
* @since 12.0
* @see #TLEPropagatorBuilder(TLE, PositionAngleType, double, DataContext, TleGenerationAlgorithm)
*/
@DefaultDataContext
public TLEPropagatorBuilder(final TLE templateTLE, final PositionAngleType positionAngleType,
final double positionScale, final TleGenerationAlgorithm generationAlgorithm) {
this(templateTLE, positionAngleType, positionScale, DataContext.getDefault(), generationAlgorithm);
}
/** Build a new instance.
* <p>
* The template TLE is used as a model to {@link
* #createInitialOrbit() create initial orbit}. It defines the
* inertial frame, the central attraction coefficient, orbit type, satellite number,
* classification, .... and is also used together with the {@code positionScale} to
* convert from the {@link ParameterDriver#setNormalizedValue(double) normalized}
* parameters used by the callers of this builder to the real orbital parameters.
* The default attitude provider is aligned with the orbit's inertial frame.
* </p>
* @param templateTLE reference TLE from which real orbits will be built
* @param positionAngleType position angle type to use
* @param positionScale scaling factor used for orbital parameters normalization
* (typically set to the expected standard deviation of the position)
* @param dataContext used to access frames and time scales.
* @param generationAlgorithm TLE generation algorithm
* @since 12.0
*/
public TLEPropagatorBuilder(final TLE templateTLE, final PositionAngleType positionAngleType,
final double positionScale, final DataContext dataContext,
final TleGenerationAlgorithm generationAlgorithm) {
super(TLEPropagator.selectExtrapolator(templateTLE, dataContext.getFrames().getTEME()).getInitialState().getOrbit(),
positionAngleType, positionScale, false, FrameAlignedProvider.of(dataContext.getFrames().getTEME()));
// Supported parameters: Bstar
addSupportedParameters(templateTLE.getParametersDrivers());
this.templateTLE = templateTLE;
this.dataContext = dataContext;
this.generationAlgorithm = generationAlgorithm;
}
/** {@inheritDoc} */
@Override
public TLEPropagatorBuilder copy() {
return new TLEPropagatorBuilder(templateTLE, getPositionAngleType(), getPositionScale(),
dataContext, generationAlgorithm);
}
/** {@inheritDoc} */
@Override
public TLEPropagator buildPropagator(final double[] normalizedParameters) {
// create the orbit
setParameters(normalizedParameters);
final Orbit orbit = createInitialOrbit();
final SpacecraftState state = new SpacecraftState(orbit);
final Frame teme = dataContext.getFrames().getTEME();
// TLE related to the orbit
final TLE tle = generationAlgorithm.generate(state, templateTLE);
final List<ParameterDriver> drivers = templateTLE.getParametersDrivers();
for (int index = 0; index < drivers.size(); index++) {
if (drivers.get(index).isSelected()) {
tle.getParametersDrivers().get(index).setSelected(true);
}
}
// propagator
return TLEPropagator.selectExtrapolator(tle, getAttitudeProvider(), Propagator.DEFAULT_MASS, teme);
}
/** Getter for the template TLE.
* @return the template TLE
*/
public TLE getTemplateTLE() {
return templateTLE;
}
/** {@inheritDoc} */
@Override
public AbstractBatchLSModel buildLeastSquaresModel(final PropagatorBuilder[] builders,
final List<ObservedMeasurement<?>> measurements,
final ParameterDriversList estimatedMeasurementsParameters,
final ModelObserver observer) {
return new BatchLSModel(builders, measurements, estimatedMeasurementsParameters, observer);
}
}