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17 package org.orekit.estimation.measurements.generation;
18
19 import org.hipparchus.linear.MatrixUtils;
20 import org.hipparchus.linear.RealMatrix;
21 import org.hipparchus.random.CorrelatedRandomVectorGenerator;
22 import org.hipparchus.random.GaussianRandomGenerator;
23 import org.hipparchus.random.RandomGenerator;
24 import org.hipparchus.random.Well19937a;
25 import org.hipparchus.util.FastMath;
26 import org.junit.jupiter.api.Assertions;
27 import org.junit.jupiter.api.BeforeEach;
28 import org.junit.jupiter.api.Test;
29 import org.orekit.estimation.Context;
30 import org.orekit.estimation.EstimationTestUtils;
31 import org.orekit.estimation.Force;
32 import org.orekit.estimation.measurements.EstimatedMeasurementBase;
33 import org.orekit.estimation.measurements.ObservableSatellite;
34 import org.orekit.estimation.measurements.Position;
35 import org.orekit.estimation.measurements.modifiers.Bias;
36 import org.orekit.orbits.OrbitType;
37 import org.orekit.orbits.PositionAngleType;
38 import org.orekit.propagation.Propagator;
39 import org.orekit.propagation.SpacecraftState;
40 import org.orekit.propagation.conversion.NumericalPropagatorBuilder;
41 import org.orekit.time.AbsoluteDate;
42 import org.orekit.time.BurstSelector;
43 import org.orekit.time.TimeScalesFactory;
44
45 import java.util.SortedSet;
46
47 public class PositionBuilderTest {
48
49 private static final double SIGMA = 10.0;
50 private static final double BIAS = 5.0;
51
52 private MeasurementBuilder<Position> getBuilder(final RandomGenerator random, final ObservableSatellite satellite) {
53 final RealMatrix covariance = MatrixUtils.createRealDiagonalMatrix(new double[] {
54 SIGMA * SIGMA, SIGMA * SIGMA, SIGMA * SIGMA
55 });
56 MeasurementBuilder<Position> pb =
57 new PositionBuilder(random == null ? null : new CorrelatedRandomVectorGenerator(covariance,
58 1.0e-10,
59 new GaussianRandomGenerator(random)),
60 SIGMA, 1.0, satellite);
61 pb.addModifier(new Bias<>(new String[] { "pxBias", "pyBias", "pzBias" },
62 new double[] { BIAS, BIAS, BIAS },
63 new double[] { 1.0, 1.0, 1.0 },
64 new double[] { Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY, Double.NEGATIVE_INFINITY },
65 new double[] { Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY, Double.POSITIVE_INFINITY }));
66 return pb;
67 }
68
69 @Test
70 public void testForward() {
71 doTest(0x292b6e87436fe4c7L, 0.0, 1.2, 3.3 * SIGMA);
72 }
73
74 @Test
75 public void testBackward() {
76 doTest(0x2f3285aa70b83c47L, 0.0, -1.0, 3.3 * SIGMA);
77 }
78
79 private Propagator buildPropagator() {
80 return EstimationTestUtils.createPropagator(context.initialOrbit, propagatorBuilder);
81 }
82
83 private void doTest(long seed, double startPeriod, double endPeriod, double tolerance) {
84 Generator generator = new Generator();
85 final int maxBurstSize = 10;
86 final double highRateStep = 5.0;
87 final double burstPeriod = 300.0;
88
89 generator.addPropagator(buildPropagator());
90 generator.addPropagator(buildPropagator());
91 ObservableSatellite satellite = generator.addPropagator(buildPropagator());
92 generator.addPropagator(buildPropagator());
93 generator.addScheduler(new ContinuousScheduler<>(getBuilder(new Well19937a(seed), satellite),
94 new BurstSelector(maxBurstSize, highRateStep, burstPeriod,
95 TimeScalesFactory.getUTC())));
96 final GatheringSubscriber gatherer = new GatheringSubscriber();
97 generator.addSubscriber(gatherer);
98 final double period = context.initialOrbit.getKeplerianPeriod();
99 AbsoluteDate t0 = context.initialOrbit.getDate().shiftedBy(startPeriod * period);
100 AbsoluteDate t1 = context.initialOrbit.getDate().shiftedBy(endPeriod * period);
101 generator.generate(t0, t1);
102 SortedSet<EstimatedMeasurementBase<?>> measurements = gatherer.getGeneratedMeasurements();
103 Propagator propagator = buildPropagator();
104 double maxError = 0;
105 AbsoluteDate previous = null;
106 AbsoluteDate tInf = t0.isBefore(t1) ? t0 : t1;
107 AbsoluteDate tSup = t0.isBefore(t1) ? t1 : t0;
108 int count = 0;
109 for (EstimatedMeasurementBase<?> measurement : measurements) {
110 AbsoluteDate date = measurement.getDate();
111 double[] m = measurement.getObservedValue();
112 Assertions.assertTrue(date.compareTo(tInf) >= 0);
113 Assertions.assertTrue(date.compareTo(tSup) <= 0);
114 if (previous != null) {
115
116
117
118 final double expected = (count % maxBurstSize == 0) ?
119 burstPeriod - (maxBurstSize - 1) * highRateStep :
120 highRateStep;
121 if (t0.isBefore(t1)) {
122
123 Assertions.assertEquals(expected, date.durationFrom(previous), 1.0e-10 * expected);
124 } else {
125
126 Assertions.assertEquals(expected, previous.durationFrom(date), 1.0e-10 * expected);
127 }
128 }
129 previous = date;
130 ++count;
131 SpacecraftState state = propagator.propagate(date);
132 double[] e = measurement.
133 getObservedMeasurement().
134 estimateWithoutDerivatives(new SpacecraftState[] { state }).
135 getEstimatedValue();
136 for (int i = 0; i < m.length; ++i) {
137 maxError = FastMath.max(maxError, FastMath.abs(e[i] - m[i]));
138 }
139 }
140 Assertions.assertEquals(0.0, maxError, tolerance);
141 }
142
143 @BeforeEach
144 public void setUp() {
145 context = EstimationTestUtils.eccentricContext("regular-data:potential:tides");
146
147 propagatorBuilder = context.createBuilder(OrbitType.KEPLERIAN, PositionAngleType.TRUE, true,
148 1.0e-6, 300.0, 0.001, Force.POTENTIAL,
149 Force.THIRD_BODY_SUN, Force.THIRD_BODY_MOON);
150 }
151
152 Context context;
153 NumericalPropagatorBuilder propagatorBuilder;
154
155 }