1 /* Copyright 2002-2025 CS GROUP
2 * Licensed to CS GROUP (CS) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * CS licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.orekit.propagation.numerical;
18
19 import java.util.ArrayList;
20 import java.util.Arrays;
21 import java.util.Collections;
22 import java.util.List;
23
24 import org.hipparchus.CalculusFieldElement;
25 import org.hipparchus.Field;
26 import org.hipparchus.geometry.euclidean.threed.FieldVector3D;
27 import org.hipparchus.ode.FieldODEIntegrator;
28 import org.hipparchus.util.MathArrays;
29 import org.orekit.annotation.DefaultDataContext;
30 import org.orekit.attitudes.AttitudeProvider;
31 import org.orekit.attitudes.AttitudeProviderModifier;
32 import org.orekit.attitudes.FieldAttitude;
33 import org.orekit.data.DataContext;
34 import org.orekit.errors.OrekitException;
35 import org.orekit.errors.OrekitIllegalArgumentException;
36 import org.orekit.errors.OrekitInternalError;
37 import org.orekit.errors.OrekitMessages;
38 import org.orekit.forces.ForceModel;
39 import org.orekit.forces.gravity.NewtonianAttraction;
40 import org.orekit.frames.Frame;
41 import org.orekit.orbits.FieldOrbit;
42 import org.orekit.orbits.OrbitType;
43 import org.orekit.orbits.PositionAngleType;
44 import org.orekit.propagation.CartesianToleranceProvider;
45 import org.orekit.propagation.FieldSpacecraftState;
46 import org.orekit.propagation.PropagationType;
47 import org.orekit.propagation.Propagator;
48 import org.orekit.propagation.ToleranceProvider;
49 import org.orekit.propagation.events.FieldEventDetector;
50 import org.orekit.propagation.integration.FieldAbstractIntegratedPropagator;
51 import org.orekit.propagation.integration.FieldStateMapper;
52 import org.orekit.time.AbsoluteDate;
53 import org.orekit.time.FieldAbsoluteDate;
54 import org.orekit.utils.FieldAbsolutePVCoordinates;
55 import org.orekit.utils.ParameterDriver;
56 import org.orekit.utils.ParameterObserver;
57 import org.orekit.utils.TimeSpanMap;
58 import org.orekit.utils.TimeStampedFieldPVCoordinates;
59
60 /** This class propagates {@link org.orekit.orbits.FieldOrbit orbits} using
61 * numerical integration.
62 * <p>Numerical propagation is much more accurate than analytical propagation
63 * like for example {@link org.orekit.propagation.analytical.KeplerianPropagator
64 * Keplerian} or {@link org.orekit.propagation.analytical.EcksteinHechlerPropagator
65 * Eckstein-Hechler}, but requires a few more steps to set up to be used properly.
66 * Whereas analytical propagators are configured only thanks to their various
67 * constructors and can be used immediately after construction, numerical propagators
68 * configuration involve setting several parameters between construction time
69 * and propagation time.</p>
70 * <p>The configuration parameters that can be set are:</p>
71 * <ul>
72 * <li>the initial spacecraft state ({@link #setInitialState(FieldSpacecraftState)})</li>
73 * <li>the central attraction coefficient ({@link #setMu(CalculusFieldElement)})</li>
74 * <li>the various force models ({@link #addForceModel(ForceModel)},
75 * {@link #removeForceModels()})</li>
76 * <li>the {@link OrbitType type} of orbital parameters to be used for propagation
77 * ({@link #setOrbitType(OrbitType)}),
78 * <li>the {@link PositionAngleType type} of position angle to be used in orbital parameters
79 * to be used for propagation where it is relevant ({@link
80 * #setPositionAngleType(PositionAngleType)}),
81 * <li>whether {@link org.orekit.propagation.integration.FieldAdditionalDerivativesProvider additional derivatives providers}
82 * should be propagated along with orbital state
83 * ({@link #addAdditionalDerivativesProvider(org.orekit.propagation.integration.FieldAdditionalDerivativesProvider)}),
84 * <li>the discrete events that should be triggered during propagation
85 * ({@link #addEventDetector(FieldEventDetector)},
86 * {@link #clearEventsDetectors()})</li>
87 * <li>the binding logic with the rest of the application ({@link #getMultiplexer()})</li>
88 * </ul>
89 * <p>From these configuration parameters, only the initial state is mandatory. The default
90 * propagation settings are in {@link OrbitType#EQUINOCTIAL equinoctial} parameters with
91 * {@link PositionAngleType#ECCENTRIC} longitude argument. If the central attraction coefficient
92 * is not explicitly specified, the one used to define the initial orbit will be used.
93 * However, specifying only the initial state and perhaps the central attraction coefficient
94 * would mean the propagator would use only Keplerian forces. In this case, the simpler {@link
95 * org.orekit.propagation.analytical.KeplerianPropagator KeplerianPropagator} class would
96 * perhaps be more effective.</p>
97 * <p>The underlying numerical integrator set up in the constructor may also have its own
98 * configuration parameters. Typical configuration parameters for adaptive stepsize integrators
99 * are the min, max and perhaps start step size as well as the absolute and/or relative errors
100 * thresholds.</p>
101 * <p>The state that is seen by the integrator is a simple seven elements double array.
102 * The six first elements are either:
103 * <ul>
104 * <li>the {@link org.orekit.orbits.FieldEquinoctialOrbit equinoctial orbit parameters} (a, e<sub>x</sub>,
105 * e<sub>y</sub>, h<sub>x</sub>, h<sub>y</sub>, λ<sub>M</sub> or λ<sub>E</sub>
106 * or λ<sub>v</sub>) in meters and radians,</li>
107 * <li>the {@link org.orekit.orbits.FieldKeplerianOrbit Keplerian orbit parameters} (a, e, i, ω, Ω,
108 * M or E or v) in meters and radians,</li>
109 * <li>the {@link org.orekit.orbits.FieldCircularOrbit circular orbit parameters} (a, e<sub>x</sub>, e<sub>y</sub>, i,
110 * Ω, α<sub>M</sub> or α<sub>E</sub> or α<sub>v</sub>) in meters
111 * and radians,</li>
112 * <li>the {@link org.orekit.orbits.FieldCartesianOrbit Cartesian orbit parameters} (x, y, z, v<sub>x</sub>,
113 * v<sub>y</sub>, v<sub>z</sub>) in meters and meters per seconds.
114 * </ul>
115 * The last element is the mass in kilograms.
116 * <p>The following code snippet shows a typical setting for Low Earth Orbit propagation in
117 * equinoctial parameters and true longitude argument:</p>
118 * <pre>
119 * final T zero = field.getZero();
120 * final T dP = zero.add(0.001);
121 * final T minStep = zero.add(0.001);
122 * final T maxStep = zero.add(500);
123 * final T initStep = zero.add(60);
124 * final double[][] tolerance = ToleranceProvider.getDefaultToleranceProvider(dP).getTolerances(orbit, OrbitType.EQUINOCTIAL);
125 * AdaptiveStepsizeFieldIntegrator<T> integrator = new DormandPrince853FieldIntegrator<>(field, minStep, maxStep, tolerance[0], tolerance[1]);
126 * integrator.setInitialStepSize(initStep);
127 * propagator = new FieldNumericalPropagator<>(field, integrator);
128 * </pre>
129 * <p>By default, at the end of the propagation, the propagator resets the initial state to the final state,
130 * thus allowing a new propagation to be started from there without recomputing the part already performed.
131 * This behaviour can be changed by calling {@link #setResetAtEnd(boolean)}.
132 * </p>
133 * <p>Beware the same instance cannot be used simultaneously by different threads, the class is <em>not</em>
134 * thread-safe.</p>
135
136 * @see FieldSpacecraftState
137 * @see ForceModel
138 * @see org.orekit.propagation.sampling.FieldOrekitStepHandler
139 * @see org.orekit.propagation.sampling.FieldOrekitFixedStepHandler
140 * @see org.orekit.propagation.integration.FieldIntegratedEphemeris
141 * @see FieldTimeDerivativesEquations
142 *
143 * @author Mathieu Roméro
144 * @author Luc Maisonobe
145 * @author Guylaine Prat
146 * @author Fabien Maussion
147 * @author Véronique Pommier-Maurussane
148 * @param <T> type of the field elements
149 */
150 public class FieldNumericalPropagator<T extends CalculusFieldElement<T>> extends FieldAbstractIntegratedPropagator<T> {
151
152 /** Force models used during the extrapolation of the FieldOrbit<T>, without Jacobians. */
153 private final List<ForceModel> forceModels;
154
155 /** Field used by this class.*/
156 private final Field<T> field;
157
158 /** boolean to ignore or not the creation of a NewtonianAttraction. */
159 private boolean ignoreCentralAttraction = false;
160
161 /**
162 * boolean to know if a full attitude (with rates) is needed when computing derivatives for the ODE.
163 */
164 private boolean needFullAttitudeForDerivatives = true;
165
166 /** Create a new instance of NumericalPropagator, based on orbit definition mu.
167 * After creation, the instance is empty, i.e. the attitude provider is set to an
168 * unspecified default law and there are no perturbing forces at all.
169 * This means that if {@link #addForceModel addForceModel} is not
170 * called after creation, the integrated orbit will follow a Keplerian
171 * evolution only. The defaults are {@link OrbitType#EQUINOCTIAL}
172 * for {@link #setOrbitType(OrbitType) propagation
173 * orbit type} and {@link PositionAngleType#ECCENTRIC} for {@link
174 * #setPositionAngleType(PositionAngleType) position angle type}.
175 *
176 * <p>This constructor uses the {@link DataContext#getDefault() default data context}.
177 *
178 * @param integrator numerical integrator to use for propagation.
179 * @param field Field used by default
180 * @see #FieldNumericalPropagator(Field, FieldODEIntegrator, AttitudeProvider)
181 */
182 @DefaultDataContext
183 public FieldNumericalPropagator(final Field<T> field, final FieldODEIntegrator<T> integrator) {
184 this(field, integrator, Propagator.getDefaultLaw(DataContext.getDefault().getFrames()));
185 }
186
187 /** Create a new instance of NumericalPropagator, based on orbit definition mu.
188 * After creation, the instance is empty, i.e. the attitude provider is set to an
189 * unspecified default law and there are no perturbing forces at all.
190 * This means that if {@link #addForceModel addForceModel} is not
191 * called after creation, the integrated orbit will follow a Keplerian
192 * evolution only. The defaults are {@link OrbitType#EQUINOCTIAL}
193 * for {@link #setOrbitType(OrbitType) propagation
194 * orbit type} and {@link PositionAngleType#ECCENTRIC} for {@link
195 * #setPositionAngleType(PositionAngleType) position angle type}.
196 * @param field Field used by default
197 * @param integrator numerical integrator to use for propagation.
198 * @param attitudeProvider attitude law to use.
199 * @since 10.1
200 */
201 public FieldNumericalPropagator(final Field<T> field,
202 final FieldODEIntegrator<T> integrator,
203 final AttitudeProvider attitudeProvider) {
204 super(field, integrator, PropagationType.OSCULATING);
205 this.field = field;
206 forceModels = new ArrayList<>();
207 initMapper(field);
208 setAttitudeProvider(attitudeProvider);
209 setMu(field.getZero().add(Double.NaN));
210 clearStepHandlers();
211 setOrbitType(NumericalPropagator.DEFAULT_ORBIT_TYPE);
212 setPositionAngleType(NumericalPropagator.DEFAULT_POSITION_ANGLE_TYPE);
213 }
214
215 /** Set the flag to ignore or not the creation of a {@link NewtonianAttraction}.
216 * @param ignoreCentralAttraction if true, {@link NewtonianAttraction} is <em>not</em>
217 * added automatically if missing
218 */
219 public void setIgnoreCentralAttraction(final boolean ignoreCentralAttraction) {
220 this.ignoreCentralAttraction = ignoreCentralAttraction;
221 }
222
223 /** Set the central attraction coefficient μ.
224 * <p>
225 * Setting the central attraction coefficient is
226 * equivalent to {@link #addForceModel(ForceModel) add}
227 * a {@link NewtonianAttraction} force model.
228 * </p>
229 * @param mu central attraction coefficient (m³/s²)
230 * @see #addForceModel(ForceModel)
231 * @see #getAllForceModels()
232 */
233 @Override
234 public void setMu(final T mu) {
235 if (ignoreCentralAttraction) {
236 superSetMu(mu);
237 } else {
238 addForceModel(new NewtonianAttraction(mu.getReal()));
239 }
240 }
241
242 /** Set the central attraction coefficient μ only in upper class.
243 * @param mu central attraction coefficient (m³/s²)
244 */
245 private void superSetMu(final T mu) {
246 super.setMu(mu);
247 }
248
249 /** Check if Newtonian attraction force model is available.
250 * <p>
251 * Newtonian attraction is always the last force model in the list.
252 * </p>
253 * @return true if Newtonian attraction force model is available
254 */
255 private boolean hasNewtonianAttraction() {
256 final int last = forceModels.size() - 1;
257 return last >= 0 && forceModels.get(last) instanceof NewtonianAttraction;
258 }
259
260 /** Add a force model to the global perturbation model.
261 * <p>If this method is not called at all, the integrated orbit will follow
262 * a Keplerian evolution only.</p>
263 * @param model perturbing {@link ForceModel} to add
264 * @see #removeForceModels()
265 * @see #setMu(CalculusFieldElement)
266 */
267 public void addForceModel(final ForceModel model) {
268
269 if (model instanceof NewtonianAttraction) {
270 // we want to add the central attraction force model
271
272 try {
273 // ensure we are notified of any mu change
274 model.getParametersDrivers().get(0).addObserver(new ParameterObserver() {
275 /** {@inheritDoc} */
276 @Override
277 public void valueChanged(final double previousValue, final ParameterDriver driver, final AbsoluteDate date) {
278 // mu PDriver should have only 1 span
279 superSetMu(field.getZero().newInstance(driver.getValue(date)));
280 }
281 /** {@inheritDoc} */
282 @Override
283 public void valueSpanMapChanged(final TimeSpanMap<Double> previousValue, final ParameterDriver driver) {
284 // mu PDriver should have only 1 span
285 superSetMu(field.getZero().newInstance(driver.getValue()));
286 }
287 });
288 } catch (OrekitException oe) {
289 // this should never happen
290 throw new OrekitInternalError(oe);
291 }
292
293 if (hasNewtonianAttraction()) {
294 // there is already a central attraction model, replace it
295 forceModels.set(forceModels.size() - 1, model);
296 } else {
297 // there are no central attraction model yet, add it at the end of the list
298 forceModels.add(model);
299 }
300 } else {
301 // we want to add a perturbing force model
302 if (hasNewtonianAttraction()) {
303 // insert the new force model before Newtonian attraction,
304 // which should always be the last one in the list
305 forceModels.add(forceModels.size() - 1, model);
306 } else {
307 // we only have perturbing force models up to now, just append at the end of the list
308 forceModels.add(model);
309 }
310 }
311
312 }
313
314 /** Remove all perturbing force models from the global perturbation model.
315 * <p>Once all perturbing forces have been removed (and as long as no new force
316 * model is added), the integrated orbit will follow a Keplerian evolution
317 * only.</p>
318 * @see #addForceModel(ForceModel)
319 */
320 public void removeForceModels() {
321 forceModels.clear();
322 }
323
324 /** Get all the force models, perturbing forces and Newtonian attraction included.
325 * @return list of perturbing force models, with Newtonian attraction being the
326 * last one
327 * @see #addForceModel(ForceModel)
328 * @see #setMu(CalculusFieldElement)
329 * @since 9.1
330 */
331 public List<ForceModel> getAllForceModels() {
332 return Collections.unmodifiableList(forceModels);
333 }
334
335 /** Set propagation orbit type.
336 * @param orbitType orbit type to use for propagation
337 */
338 @Override
339 public void setOrbitType(final OrbitType orbitType) {
340 super.setOrbitType(orbitType);
341 }
342
343 /** Get propagation parameter type.
344 * @return orbit type used for propagation
345 */
346 @Override
347 public OrbitType getOrbitType() {
348 return superGetOrbitType();
349 }
350
351 /** Get propagation parameter type.
352 * @return orbit type used for propagation
353 */
354 private OrbitType superGetOrbitType() {
355 return super.getOrbitType();
356 }
357
358 /** Set position angle type.
359 * <p>
360 * The position parameter type is meaningful only if {@link
361 * #getOrbitType() propagation orbit type}
362 * support it. As an example, it is not meaningful for propagation
363 * in {@link OrbitType#CARTESIAN Cartesian} parameters.
364 * </p>
365 * @param positionAngleType angle type to use for propagation
366 */
367 @Override
368 public void setPositionAngleType(final PositionAngleType positionAngleType) {
369 super.setPositionAngleType(positionAngleType);
370 }
371
372 /** Get propagation parameter type.
373 * @return angle type to use for propagation
374 */
375 @Override
376 public PositionAngleType getPositionAngleType() {
377 return super.getPositionAngleType();
378 }
379
380 /** Set the initial state.
381 * @param initialState initial state
382 */
383 public void setInitialState(final FieldSpacecraftState<T> initialState) {
384 resetInitialState(initialState);
385 }
386
387 /** {@inheritDoc} */
388 @Override
389 public void resetInitialState(final FieldSpacecraftState<T> state) {
390 super.resetInitialState(state);
391 if (!hasNewtonianAttraction()) {
392 setMu(state.getOrbit().getMu());
393 }
394 setStartDate(state.getDate());
395 }
396
397 /** {@inheritDoc} */
398 @Override
399 protected AttitudeProvider initializeAttitudeProviderForDerivatives() {
400 final AttitudeProvider attitudeProvider = getAttitudeProvider();
401 return needFullAttitudeForDerivatives ? attitudeProvider :
402 AttitudeProviderModifier.getFrozenAttitudeProvider(attitudeProvider);
403 }
404
405 /** {@inheritDoc} */
406 protected FieldStateMapper<T> createMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
407 final OrbitType orbitType, final PositionAngleType positionAngleType,
408 final AttitudeProvider attitudeProvider, final Frame frame) {
409 return new FieldOsculatingMapper(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
410 }
411
412 /** Internal mapper using directly osculating parameters. */
413 private class FieldOsculatingMapper extends FieldStateMapper<T> {
414
415 /** Simple constructor.
416 * <p>
417 * The position parameter type is meaningful only if {@link
418 * #getOrbitType() propagation orbit type}
419 * support it. As an example, it is not meaningful for propagation
420 * in {@link OrbitType#CARTESIAN Cartesian} parameters.
421 * </p>
422 * @param referenceDate reference date
423 * @param mu central attraction coefficient (m³/s²)
424 * @param orbitType orbit type to use for mapping
425 * @param positionAngleType angle type to use for propagation
426 * @param attitudeProvider attitude provider
427 * @param frame inertial frame
428 */
429 FieldOsculatingMapper(final FieldAbsoluteDate<T> referenceDate, final T mu,
430 final OrbitType orbitType, final PositionAngleType positionAngleType,
431 final AttitudeProvider attitudeProvider, final Frame frame) {
432 super(referenceDate, mu, orbitType, positionAngleType, attitudeProvider, frame);
433 }
434
435 /** {@inheritDoc} */
436 public FieldSpacecraftState<T> mapArrayToState(final FieldAbsoluteDate<T> date, final T[] y, final T[] yDot,
437 final PropagationType type) {
438 // the parameter type is ignored for the Numerical Propagator
439
440 final T mass = y[6];
441 if (mass.getReal() <= 0.0) {
442 throw new OrekitException(OrekitMessages.NOT_POSITIVE_SPACECRAFT_MASS, mass);
443 }
444
445 if (superGetOrbitType() == null) {
446 // propagation uses absolute position-velocity-acceleration
447 final FieldVector3D<T> p = new FieldVector3D<>(y[0], y[1], y[2]);
448 final FieldVector3D<T> v = new FieldVector3D<>(y[3], y[4], y[5]);
449 final FieldVector3D<T> a;
450 final FieldAbsolutePVCoordinates<T> absPva;
451 if (yDot == null) {
452 absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, FieldVector3D.getZero(date.getField())));
453 } else {
454 a = new FieldVector3D<>(yDot[3], yDot[4], yDot[5]);
455 absPva = new FieldAbsolutePVCoordinates<>(getFrame(), new TimeStampedFieldPVCoordinates<>(date, p, v, a));
456 }
457
458 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(absPva, date, getFrame());
459 return new FieldSpacecraftState<>(absPva, attitude).withMass(mass);
460 } else {
461 // propagation uses regular orbits
462 final FieldOrbit<T> orbit = superGetOrbitType().mapArrayToOrbit(y, yDot, super.getPositionAngleType(), date, getMu(), getFrame());
463 final FieldAttitude<T> attitude = getAttitudeProvider().getAttitude(orbit, date, getFrame());
464 return new FieldSpacecraftState<>(orbit, attitude).withMass(mass);
465 }
466 }
467
468 /** {@inheritDoc} */
469 public void mapStateToArray(final FieldSpacecraftState<T> state, final T[] y, final T[] yDot) {
470 if (superGetOrbitType() == null) {
471 // propagation uses absolute position-velocity-acceleration
472 final FieldVector3D<T> p = state.getAbsPVA().getPosition();
473 final FieldVector3D<T> v = state.getAbsPVA().getVelocity();
474 y[0] = p.getX();
475 y[1] = p.getY();
476 y[2] = p.getZ();
477 y[3] = v.getX();
478 y[4] = v.getY();
479 y[5] = v.getZ();
480 y[6] = state.getMass();
481 }
482 else {
483 superGetOrbitType().mapOrbitToArray(state.getOrbit(), super.getPositionAngleType(), y, yDot);
484 y[6] = state.getMass();
485 }
486 }
487
488 }
489
490 /** {@inheritDoc} */
491 protected MainStateEquations<T> getMainStateEquations(final FieldODEIntegrator<T> integrator) {
492 return new Main(integrator);
493 }
494
495 /** Internal class for osculating parameters integration. */
496 private class Main implements MainStateEquations<T>, FieldTimeDerivativesEquations<T> {
497
498 /** Derivatives array. */
499 private final T[] yDot;
500
501 /** Current state. */
502 private FieldSpacecraftState<T> currentState;
503
504 /** Jacobian of the orbital parameters with respect to the Cartesian parameters. */
505 private T[][] jacobian;
506
507 /** Flag keeping track whether Jacobian matrix needs to be recomputed or not. */
508 private boolean recomputingJacobian;
509
510 /** Simple constructor.
511 * @param integrator numerical integrator to use for propagation.
512 */
513 Main(final FieldODEIntegrator<T> integrator) {
514
515 this.yDot = MathArrays.buildArray(getField(), 7);
516 this.jacobian = MathArrays.buildArray(getField(), 6, 6);
517 this.recomputingJacobian = true;
518
519 // feed internal event detectors
520 for (final ForceModel forceModel : forceModels) {
521 forceModel.getFieldEventDetectors(getField()).forEach(detector -> setUpEventDetector(integrator, detector));
522 }
523 getAttitudeProvider().getFieldEventDetectors(getField()).forEach(detector -> setUpEventDetector(integrator, detector));
524
525 // default value for Jacobian is identity
526 for (int i = 0; i < jacobian.length; ++i) {
527 Arrays.fill(jacobian[i], getField().getZero());
528 jacobian[i][i] = getField().getOne();
529 }
530
531 }
532
533 /** {@inheritDoc} */
534 @Override
535 public void init(final FieldSpacecraftState<T> initialState, final FieldAbsoluteDate<T> target) {
536 needFullAttitudeForDerivatives = forceModels.stream().anyMatch(ForceModel::dependsOnAttitudeRate);
537
538 forceModels.forEach(fm -> fm.init(initialState, target));
539
540 final int numberOfForces = forceModels.size();
541 final OrbitType orbitType = superGetOrbitType();
542 if (orbitType != null && orbitType != OrbitType.CARTESIAN && numberOfForces > 0) {
543 if (numberOfForces > 1) {
544 recomputingJacobian = true;
545 } else {
546 recomputingJacobian = !(forceModels.get(0) instanceof NewtonianAttraction);
547 }
548 } else {
549 recomputingJacobian = false;
550 }
551 }
552
553 /** {@inheritDoc} */
554 @Override
555 public T[] computeDerivatives(final FieldSpacecraftState<T> state) {
556 final T zero = state.getMass().getField().getZero();
557 currentState = state;
558 Arrays.fill(yDot, zero);
559 if (recomputingJacobian) {
560 // propagation uses Jacobian matrix of orbital parameters w.r.t. Cartesian ones
561 currentState.getOrbit().getJacobianWrtCartesian(getPositionAngleType(), jacobian);
562 }
563
564 // compute the contributions of all perturbing forces,
565 // using the Kepler contribution at the end since
566 // NewtonianAttraction is always the last instance in the list
567 for (final ForceModel forceModel : forceModels) {
568 forceModel.addContribution(state, this);
569 }
570
571 if (superGetOrbitType() == null) {
572 // position derivative is velocity, and was not added above in the force models
573 // (it is added when orbit type is non-null because NewtonianAttraction considers it)
574 final FieldVector3D<T> velocity = currentState.getPVCoordinates().getVelocity();
575 yDot[0] = yDot[0].add(velocity.getX());
576 yDot[1] = yDot[1].add(velocity.getY());
577 yDot[2] = yDot[2].add(velocity.getZ());
578 }
579
580 return yDot.clone();
581
582 }
583
584 /** {@inheritDoc} */
585 @Override
586 public void addKeplerContribution(final T mu) {
587 if (superGetOrbitType() == null) {
588
589 // if mu is neither 0 nor NaN, we want to include Newtonian acceleration
590 if (mu.getReal() > 0) {
591 // velocity derivative is Newtonian acceleration
592 final FieldVector3D<T> position = currentState.getPosition();
593 final T r2 = position.getNormSq();
594 final T coeff = r2.multiply(r2.sqrt()).reciprocal().negate().multiply(mu);
595 yDot[3] = yDot[3].add(coeff.multiply(position.getX()));
596 yDot[4] = yDot[4].add(coeff.multiply(position.getY()));
597 yDot[5] = yDot[5].add(coeff.multiply(position.getZ()));
598 }
599
600 } else {
601 // propagation uses regular orbits
602 currentState.getOrbit().addKeplerContribution(getPositionAngleType(), mu, yDot);
603 }
604 }
605
606 /** {@inheritDoc} */
607 @Override
608 public void addNonKeplerianAcceleration(final FieldVector3D<T> gamma) {
609 for (int i = 0; i < 6; ++i) {
610 final T[] jRow = jacobian[i];
611 yDot[i] = yDot[i].add(jRow[3].linearCombination(jRow[3], gamma.getX(),
612 jRow[4], gamma.getY(),
613 jRow[5], gamma.getZ()));
614 }
615 }
616
617 /** {@inheritDoc} */
618 @Override
619 public void addMassDerivative(final T q) {
620 if (q.getReal() > 0) {
621 throw new OrekitIllegalArgumentException(OrekitMessages.POSITIVE_FLOW_RATE, q);
622 }
623 yDot[6] = yDot[6].add(q);
624 }
625
626 }
627
628 /** Estimate tolerance vectors for integrators.
629 * <p>
630 * The errors are estimated from partial derivatives properties of orbits,
631 * starting from a scalar position error specified by the user.
632 * Considering the energy conservation equation V = sqrt(mu (2/r - 1/a)),
633 * we get at constant energy (i.e. on a Keplerian trajectory):
634 * <pre>
635 * V r² |dV| = mu |dr|
636 * </pre>
637 * So we deduce a scalar velocity error consistent with the position error.
638 * From here, we apply orbits Jacobians matrices to get consistent errors
639 * on orbital parameters.
640 * <p>
641 * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
642 * are only local estimates, not global ones. So some care must be taken when using
643 * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
644 * will guarantee a 1mm error position after several orbits integration.
645 * </p>
646 * @param dP user specified position error
647 * @param orbit reference orbit
648 * @param type propagation type for the meaning of the tolerance vectors elements
649 * (it may be different from {@code orbit.getType()})
650 * @return a two rows array, row 0 being the absolute tolerance error and row 1
651 * being the relative tolerance error
652 * @param <T> elements type
653 * @deprecated since 13.0. Use {@link ToleranceProvider} for default and custom tolerances.
654 */
655 @Deprecated
656 public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final FieldOrbit<T> orbit,
657 final OrbitType type) {
658
659 return ToleranceProvider.getDefaultToleranceProvider(dP.getReal()).getTolerances(orbit, type, PositionAngleType.TRUE);
660 }
661
662 /** Estimate tolerance vectors for integrators when propagating in orbits.
663 * <p>
664 * The errors are estimated from partial derivatives properties of orbits,
665 * starting from scalar position and velocity errors specified by the user.
666 * <p>
667 * The tolerances are only <em>orders of magnitude</em>, and integrator tolerances
668 * are only local estimates, not global ones. So some care must be taken when using
669 * these tolerances. Setting 1mm as a position error does NOT mean the tolerances
670 * will guarantee a 1mm error position after several orbits integration.
671 * </p>
672 * @param <T> elements type
673 * @param dP user specified position error
674 * @param dV user specified velocity error
675 * @param orbit reference orbit
676 * @param type propagation type for the meaning of the tolerance vectors elements
677 * (it may be different from {@code orbit.getType()})
678 * @return a two rows array, row 0 being the absolute tolerance error and row 1
679 * being the relative tolerance error
680 * @since 10.3
681 * @deprecated since 13.0. Use {@link ToleranceProvider} for default and custom tolerances.
682 */
683 @Deprecated
684 public static <T extends CalculusFieldElement<T>> double[][] tolerances(final T dP, final T dV,
685 final FieldOrbit<T> orbit,
686 final OrbitType type) {
687
688 return ToleranceProvider.of(CartesianToleranceProvider.of(dP.getReal(), dV.getReal(),
689 CartesianToleranceProvider.DEFAULT_ABSOLUTE_MASS_TOLERANCE)).getTolerances(orbit, type, PositionAngleType.TRUE);
690 }
691
692 }
693