Commit 92ce876f authored by Luc Maisonobe's avatar Luc Maisonobe
Browse files

Added masse depletion delay effect.

parent c55c70ad
/* Copyright 2002-2021 CS GROUP
* Licensed to CS GROUP (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.forces.maneuvers.jacobians;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.forces.maneuvers.Maneuver;
import org.orekit.propagation.SpacecraftState;
import org.orekit.propagation.integration.AdditionalDerivativesProvider;
import org.orekit.time.AbsoluteDate;
/** Generator for effect of delaying mass depletion when delaying a maneuver.
* @author Luc Maisonobe
* @since 11.1
*/
public class MassDepletionDelay implements AdditionalDerivativesProvider {
/** Prefix for state name. */
public static final String PREFIX = "Orekit-depletion-";
/** Name of the mass depletion additional state. */
private final String depletionName;
/** Start/stop management flag. */
private final boolean manageStart;
/** Maneuver that is delayed. */
private final Maneuver maneuver;
/** Indicator for forward propagation. */
private boolean forward;
/** Simple constructor.
* <p>
* The generated additional state and derivatives will be named by prepending
* the {@link #PREFIX} to the name of the date trigger parameter.
* </p>
* @param triggerName name of the date trigger parameter
* @param manageStart if true, we compute derivatives with respect to maneuver start
* @param maneuver maneuver that is delayed
*/
public MassDepletionDelay(final String triggerName, final boolean manageStart, final Maneuver maneuver) {
this.depletionName = PREFIX + triggerName;
this.manageStart = manageStart;
this.maneuver = maneuver;
}
/** {@inheritDoc} */
@Override
public String getName() {
return depletionName;
}
/** Get the dimension of the generated column.
* @return dimension of the generated column
*/
public int getDimension() {
return 6;
}
/** {@inheritDoc} */
@Override
public void init(final SpacecraftState initialState, final AbsoluteDate target) {
forward = target.isAfterOrEqualTo(initialState);
}
/** {@inheritDoc} */
@Override
public double[] derivatives(final SpacecraftState state) {
// retrieve current Jacobian column
final double[] p = state.getAdditionalState(getName());
final double[] pDot = new double[6];
if (forward == manageStart) {
// current acceleration
final double[] parameters = maneuver.getParameters();
final Vector3D acceleration = maneuver.acceleration(state, parameters);
// we have acceleration Γ = F/m and m = m₀ - q (t - tₛ)
// where m is current mass, m₀ is initial mass and tₛ is maneuver trigger time
// a delay dtₛ on trigger time induces delaying mass depletion
// we get: dΓ = -F/m² dm = -F/m² q dtₛ = -Γ q/m dtₛ
final double minusQ = maneuver.getPropulsionModel().getMassDerivatives(state, parameters);
final double m = state.getMass();
final double ratio = minusQ / m;
pDot[0] = p[3];
pDot[1] = p[4];
pDot[2] = p[5];
pDot[3] = ratio * acceleration.getX();
pDot[4] = ratio * acceleration.getY();
pDot[5] = ratio * acceleration.getZ();
}
return pDot;
}
}
/* Copyright 2002-2021 CS GROUP
* Licensed to CS GROUP (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.
*/
/**
* Generators for columns of Jacobian matrices related to maneuver parameters.
*/
package org.orekit.forces.maneuvers.jacobians;
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