ParametricAcceleration.java
- /* Copyright 2002-2024 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.empirical;
- import java.util.List;
- import java.util.stream.Stream;
- import org.hipparchus.CalculusFieldElement;
- import org.hipparchus.Field;
- import org.hipparchus.geometry.euclidean.threed.FieldRotation;
- import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
- import org.hipparchus.geometry.euclidean.threed.Rotation;
- import org.hipparchus.geometry.euclidean.threed.Vector3D;
- import org.orekit.attitudes.AttitudeProvider;
- import org.orekit.forces.ForceModel;
- import org.orekit.propagation.FieldSpacecraftState;
- import org.orekit.propagation.SpacecraftState;
- import org.orekit.propagation.events.EventDetector;
- import org.orekit.propagation.events.FieldEventDetector;
- import org.orekit.time.AbsoluteDate;
- import org.orekit.time.FieldAbsoluteDate;
- import org.orekit.utils.ParameterDriver;
- /** This class implements a parametric acceleration.
- * <p>Parametric accelerations are intended to model lesser-known
- * forces, estimating a few defining parameters from a parametric
- * function using orbit determination. Typical parametric functions
- * are polynomial (often limited to a constant term) and harmonic
- * (often with either orbital period or half orbital period).</p>
- * <p>An important operational example is the infamous GPS Y-bias,
- * which is thought to be related to a radiator thermal radiation.
- * Other examples could be to model leaks that produce roughly constant
- * trust in some spacecraft-related direction.</p>
- * <p>The acceleration direction is considered constant in either:
- * </p>
- * <ul>
- * <li>inertial frame</li>
- * <li>spacecraft frame</li>
- * <li>a dedicated attitude frame overriding spacecraft attitude
- * (this could for example be used to model solar arrays orientation
- * if the force is related to solar arrays)</li>
- * </ul>
- * <p>
- * If the direction of the acceleration is unknown, then three instances
- * of this class should be used, one along the X axis, one along the Y
- * axis and one along the Z axis and their parameters estimated as usual.
- * </p>
- * @since 10.3
- * @author Luc Maisonobe
- * @author Bryan Cazabonne
- * @author Melina Vanel
- */
- public class ParametricAcceleration implements ForceModel {
- /** Direction of the acceleration in defining frame. */
- private final Vector3D direction;
- /** Flag for inertial acceleration direction. */
- private final boolean isInertial;
- /** The attitude to override, if set. */
- private final AttitudeProvider attitudeOverride;
- /** Acceleration model. */
- private final AccelerationModel accelerationModel;
- /** Simple constructor.
- * @param direction acceleration direction in overridden spacecraft frame
- * @param isInertial if true, direction is defined in the same inertial
- * frame used for propagation (i.e. {@link SpacecraftState#getFrame()}),
- * otherwise direction is defined in spacecraft frame (i.e. using the
- * propagation {@link
- * org.orekit.propagation.Propagator#setAttitudeProvider(AttitudeProvider)
- * attitude law})
- * @param accelerationModel acceleration model used to compute the contribution of the empirical acceleration
- * direction
- */
- public ParametricAcceleration(final Vector3D direction,
- final boolean isInertial,
- final AccelerationModel accelerationModel) {
- this(direction, isInertial, null, accelerationModel);
- }
- /** Simple constructor.
- * @param direction acceleration direction in overridden spacecraft frame
- * frame used for propagation (i.e. {@link SpacecraftState#getFrame()}),
- * otherwise direction is defined in spacecraft frame (i.e. using the
- * propagation {@link
- * org.orekit.propagation.Propagator#setAttitudeProvider(AttitudeProvider)
- * attitude law})
- * @param attitudeOverride provider for attitude used to compute acceleration
- * @param accelerationModel acceleration model used to compute the contribution of the empirical acceleration
- * direction
- */
- public ParametricAcceleration(final Vector3D direction,
- final AttitudeProvider attitudeOverride,
- final AccelerationModel accelerationModel) {
- this(direction, false, attitudeOverride, accelerationModel);
- }
- /** Simple constructor.
- * @param direction acceleration direction in overridden spacecraft frame
- * @param isInertial if true, direction is defined in the same inertial
- * frame used for propagation (i.e. {@link SpacecraftState#getFrame()}),
- * otherwise direction is defined in spacecraft frame (i.e. using the
- * propagation {@link
- * org.orekit.propagation.Propagator#setAttitudeProvider(AttitudeProvider)
- * attitude law})
- * @param attitudeOverride provider for attitude used to compute acceleration
- * @param accelerationModel acceleration model used to compute the contribution of the empirical acceleration
- * direction
- */
- private ParametricAcceleration(final Vector3D direction,
- final boolean isInertial,
- final AttitudeProvider attitudeOverride,
- final AccelerationModel accelerationModel) {
- this.direction = direction;
- this.isInertial = isInertial;
- this.attitudeOverride = attitudeOverride;
- this.accelerationModel = accelerationModel;
- }
- /** {@inheritDoc} */
- @Override
- public boolean dependsOnPositionOnly() {
- return isInertial;
- }
- /** {@inheritDoc} */
- @Override
- public List<ParameterDriver> getParametersDrivers() {
- return accelerationModel.getParametersDrivers();
- }
- /** {@inheritDoc} */
- @Override
- public void init(final SpacecraftState initialState, final AbsoluteDate target) {
- accelerationModel.init(initialState, target);
- }
- /** {@inheritDoc} */
- @Override
- public Vector3D acceleration(final SpacecraftState state,
- final double[] parameters) {
- // Date
- final AbsoluteDate date = state.getDate();
- final Vector3D inertialDirection;
- if (isInertial) {
- // the acceleration direction is already defined in the inertial frame
- inertialDirection = direction;
- } else {
- final Rotation rotation;
- if (attitudeOverride == null) {
- // the acceleration direction is defined in spacecraft frame as set by the propagator
- rotation = state.getAttitude().getRotation();
- } else {
- // the acceleration direction is defined in a dedicated frame
- rotation = attitudeOverride.getAttitudeRotation(state.getOrbit(), date, state.getFrame());
- }
- inertialDirection = rotation.applyInverseTo(direction);
- }
- // Call the acceleration model to compute the acceleration
- return new Vector3D(accelerationModel.signedAmplitude(state, parameters), inertialDirection);
- }
- /** {@inheritDoc} */
- @Override
- public <T extends CalculusFieldElement<T>> FieldVector3D<T> acceleration(final FieldSpacecraftState<T> state,
- final T[] parameters) {
- // Date
- final FieldAbsoluteDate<T> date = state.getDate();
- final FieldVector3D<T> inertialDirection;
- if (isInertial) {
- // the acceleration direction is already defined in the inertial frame
- inertialDirection = new FieldVector3D<>(date.getField(), direction);
- } else {
- final FieldRotation<T> rotation;
- if (attitudeOverride == null) {
- // the acceleration direction is defined in spacecraft frame as set by the propagator
- rotation = state.getAttitude().getRotation();
- } else {
- // the acceleration direction is defined in a dedicated frame
- rotation = attitudeOverride.getAttitudeRotation(state.getOrbit(), date, state.getFrame());
- }
- inertialDirection = rotation.applyInverseTo(direction);
- }
- // Call the acceleration model to compute the acceleration
- return new FieldVector3D<>(accelerationModel.signedAmplitude(state, parameters), inertialDirection);
- }
- /** {@inheritDoc} */
- @Override
- public Stream<EventDetector> getEventDetectors() {
- return Stream.empty();
- }
- /** {@inheritDoc} */
- @Override
- public <T extends CalculusFieldElement<T>> Stream<FieldEventDetector<T>> getFieldEventDetectors(final Field<T> field) {
- return Stream.empty();
- }
- }