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OREKIT (ORbits Extrapolation KIT) is a low level space dynamics library.
It provides basic elements (orbits, dates, attitude, frames ...) and
various algorithms to handle them (conversions, analytical and numerical
propagation, pointing ...).
/* 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.attitudes;
import java.util.List;
import java.util.stream.Collectors;
import org.hipparchus.CalculusFieldElement;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.frames.FieldTransform;
import org.orekit.frames.Frame;
import org.orekit.frames.LOF;
import org.orekit.frames.Transform;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.FieldAbsoluteDate;
import org.orekit.time.FieldTimeInterpolator;
import org.orekit.time.TimeInterpolator;
import org.orekit.utils.AngularDerivativesFilter;
import org.orekit.utils.FieldPVCoordinates;
import org.orekit.utils.FieldPVCoordinatesProvider;
import org.orekit.utils.ImmutableTimeStampedCache;
import org.orekit.utils.PVCoordinates;
import org.orekit.utils.PVCoordinatesProvider;
import org.orekit.utils.TimeStampedAngularCoordinates;
import org.orekit.utils.TimeStampedAngularCoordinatesHermiteInterpolator;
import org.orekit.utils.TimeStampedFieldAngularCoordinates;
import org.orekit.utils.TimeStampedFieldAngularCoordinatesHermiteInterpolator;
/**
* This class handles an attitude provider interpolating from a predefined table
* containing offsets from a Local Orbital Frame.
* Instances of this class are guaranteed to be immutable.
* @see LofOffset
* @see TabulatedProvider
* @author Luc Maisonobe
* @since 7.1
*/
public class TabulatedLofOffset implements BoundedAttitudeProvider {
/** Inertial frame with respect to which orbit should be computed. */
private final Frame inertialFrame;
/** Local Orbital Frame. */
private final LOF type;
/** Cached attitude table. */
private final transient ImmutableTimeStampedCache table;
/** Filter for derivatives from the sample to use in interpolation. */
private final AngularDerivativesFilter filter;
/** First date of the range. */
private final AbsoluteDate minDate;
/** Last date of the range. */
private final AbsoluteDate maxDate;
/** Creates new instance.
*
* This constructor uses the first and last point samples as the min and max dates.
*
* @param inertialFrame inertial frame with respect to which orbit should be computed
* @param lof local orbital frame
* @param table tabulated attitudes
* @param n number of attitude to use for interpolation
* @param filter filter for derivatives from the sample to use in interpolation
*/
public TabulatedLofOffset(final Frame inertialFrame, final LOF lof,
final List table,
final int n, final AngularDerivativesFilter filter) {
this(inertialFrame, lof, table, n, filter, table.get(0).getDate(), table.get(table.size() - 1).getDate());
}
/** Creates new instance.
* @param inertialFrame inertial frame with respect to which orbit should be computed
* @param lof local orbital frame
* @param table tabulated attitudes
* @param n number of attitude to use for interpolation
* @param minDate min date to use
* @param maxDate max date to use
* @param filter filter for derivatives from the sample to use in interpolation
* @since 11.0
*/
public TabulatedLofOffset(final Frame inertialFrame, final LOF lof,
final List table,
final int n, final AngularDerivativesFilter filter,
final AbsoluteDate minDate, final AbsoluteDate maxDate) {
if (!inertialFrame.isPseudoInertial()) {
throw new OrekitException(OrekitMessages.NON_PSEUDO_INERTIAL_FRAME,
inertialFrame.getName());
}
this.inertialFrame = inertialFrame;
this.type = lof;
this.table = new ImmutableTimeStampedCache(n, table);
this.filter = filter;
this.minDate = minDate;
this.maxDate = maxDate;
}
/** Get an unmodifiable view of the tabulated attitudes.
* @return unmodifiable view of the tabulated attitudes
*/
public List getTable() {
return table.getAll();
}
/** {@inheritDoc} */
public Attitude getAttitude(final PVCoordinatesProvider pvProv,
final AbsoluteDate date, final Frame frame) {
// get attitudes sample on which interpolation will be performed
final List sample = table.getNeighbors(date).collect(Collectors.toList());
// create interpolator
final TimeInterpolator interpolator =
new TimeStampedAngularCoordinatesHermiteInterpolator(sample.size(), filter);
// interpolate
final TimeStampedAngularCoordinates interpolated = interpolator.interpolate(date, sample);
// construction of the local orbital frame, using PV from inertial frame
final PVCoordinates pv = pvProv.getPVCoordinates(date, inertialFrame);
final Transform inertialToLof = type.transformFromInertial(date, pv);
// take into account the specified start frame (which may not be an inertial one)
final Transform frameToInertial = frame.getTransformTo(inertialFrame, date);
final Transform frameToLof = new Transform(date, frameToInertial, inertialToLof);
// compose with interpolated rotation
return new Attitude(date, frame,
interpolated.addOffset(frameToLof.getAngular()));
}
/** {@inheritDoc} */
public > FieldAttitude getAttitude(final FieldPVCoordinatesProvider pvProv,
final FieldAbsoluteDate date,
final Frame frame) {
// get attitudes sample on which interpolation will be performed
final List> sample =
table.
getNeighbors(date.toAbsoluteDate()).
map(ac -> new TimeStampedFieldAngularCoordinates<>(date.getField(), ac)).
collect(Collectors.toList());
// create interpolator
final FieldTimeInterpolator, T> interpolator =
new TimeStampedFieldAngularCoordinatesHermiteInterpolator<>(sample.size(), filter);
// interpolate
final TimeStampedFieldAngularCoordinates interpolated = interpolator.interpolate(date, sample);
// construction of the local orbital frame, using PV from inertial frame
final FieldPVCoordinates pv = pvProv.getPVCoordinates(date, inertialFrame);
final FieldTransform inertialToLof = type.transformFromInertial(date, pv);
// take into account the specified start frame (which may not be an inertial one)
final FieldTransform frameToInertial = frame.getTransformTo(inertialFrame, date);
final FieldTransform frameToLof = new FieldTransform<>(date, frameToInertial, inertialToLof);
// compose with interpolated rotation
return new FieldAttitude<>(date, frame,
interpolated.addOffset(frameToLof.getAngular()));
}
/** {@inheritDoc} */
public AbsoluteDate getMinDate() {
return minDate;
}
/** {@inheritDoc} */
public AbsoluteDate getMaxDate() {
return maxDate;
}
}