EcksteinHechlerPropagatorBuilder.java
/* Copyright 2002-2018 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.propagation.conversion;
import org.orekit.errors.OrekitException;
import org.orekit.forces.gravity.potential.GravityFieldFactory;
import org.orekit.forces.gravity.potential.TideSystem;
import org.orekit.forces.gravity.potential.UnnormalizedSphericalHarmonicsProvider;
import org.orekit.orbits.Orbit;
import org.orekit.orbits.OrbitType;
import org.orekit.orbits.PositionAngle;
import org.orekit.propagation.Propagator;
import org.orekit.propagation.analytical.EcksteinHechlerPropagator;
/** Builder for Eckstein-Hechler propagator.
* @author Pascal Parraud
* @since 6.0
*/
public class EcksteinHechlerPropagatorBuilder extends AbstractPropagatorBuilder {
/** Provider for un-normalized coefficients. */
private final UnnormalizedSphericalHarmonicsProvider provider;
/** Build a new instance.
* <p>
* The template orbit is used as a model to {@link
* #createInitialOrbit() create initial orbit}. It defines the
* inertial frame, the central attraction coefficient, the orbit type, and is also
* used together with the {@code positionScale} to convert from the {@link
* org.orekit.utils.ParameterDriver#setNormalizedValue(double) normalized} parameters used by the
* callers of this builder to the real orbital parameters.
* </p>
* @param templateOrbit reference orbit from which real orbits will be built
* (note that the mu from this orbit will be overridden with the mu from the
* {@code provider})
* @param provider for un-normalized zonal coefficients
* @param positionAngle position angle type to use
* @param positionScale scaling factor used for orbital parameters normalization
* (typically set to the expected standard deviation of the position)
* @exception OrekitException if parameters drivers cannot be scaled
* @since 8.0
*/
public EcksteinHechlerPropagatorBuilder(final Orbit templateOrbit,
final UnnormalizedSphericalHarmonicsProvider provider,
final PositionAngle positionAngle,
final double positionScale)
throws OrekitException {
super(overrideMu(templateOrbit, provider, positionAngle), positionAngle, positionScale, true);
this.provider = provider;
}
/** Build a new instance.
* <p>
* The template orbit is used as a model to {@link
* #createInitialOrbit() create initial orbit}. It defines the
* inertial frame, the central attraction coefficient, the orbit type, and is also
* used together with the {@code positionScale} to convert from the {@link
* org.orekit.utils.ParameterDriver#setNormalizedValue(double) normalized} parameters used by the
* callers of this builder to the real orbital parameters.
* </p>
* @param templateOrbit reference orbit from which real orbits will be built
* (note that the mu from this orbit will be overridden with the mu from the
* {@code provider})
* @param referenceRadius reference radius of the Earth for the potential model (m)
* @param mu central attraction coefficient (m³/s²)
* @param tideSystem tide system
* @param c20 un-normalized zonal coefficient (about -1.08e-3 for Earth)
* @param c30 un-normalized zonal coefficient (about +2.53e-6 for Earth)
* @param c40 un-normalized zonal coefficient (about +1.62e-6 for Earth)
* @param c50 un-normalized zonal coefficient (about +2.28e-7 for Earth)
* @param c60 un-normalized zonal coefficient (about -5.41e-7 for Earth)
* @param orbitType orbit type to use
* @param positionAngle position angle type to use
* @param positionScale scaling factor used for orbital parameters normalization
* (typically set to the expected standard deviation of the position)
* @exception OrekitException if parameters drivers cannot be scaled
* @since 8.0
*/
public EcksteinHechlerPropagatorBuilder(final Orbit templateOrbit,
final double referenceRadius,
final double mu,
final TideSystem tideSystem,
final double c20,
final double c30,
final double c40,
final double c50,
final double c60,
final OrbitType orbitType,
final PositionAngle positionAngle,
final double positionScale)
throws OrekitException {
this(templateOrbit,
GravityFieldFactory.getUnnormalizedProvider(referenceRadius, mu, tideSystem,
new double[][] {
{
0
}, {
0
}, {
c20
}, {
c30
}, {
c40
}, {
c50
}, {
c60
}
}, new double[][] {
{
0
}, {
0
}, {
0
}, {
0
}, {
0
}, {
0
}, {
0
}
}),
positionAngle, positionScale);
}
/** Override central attraction coefficient.
* @param templateOrbit template orbit
* @param provider gravity field provider
* @param positionAngle position angle type to use
* @return orbit with overridden central attraction coefficient
* @exception OrekitException if orbit cannot be converted
*/
private static Orbit overrideMu(final Orbit templateOrbit,
final UnnormalizedSphericalHarmonicsProvider provider,
final PositionAngle positionAngle)
throws OrekitException {
final double[] parameters = new double[6];
final double[] parametersDot = templateOrbit.hasDerivatives() ? new double[6] : null;
templateOrbit.getType().mapOrbitToArray(templateOrbit, positionAngle, parameters, parametersDot);
return templateOrbit.getType().mapArrayToOrbit(parameters, parametersDot, positionAngle,
templateOrbit.getDate(),
provider.getMu(),
templateOrbit.getFrame());
}
/** {@inheritDoc} */
public Propagator buildPropagator(final double[] normalizedParameters)
throws OrekitException {
setParameters(normalizedParameters);
return new EcksteinHechlerPropagator(createInitialOrbit(), provider);
}
}