PVBuilder.java

  1. /* Copyright 2002-2019 CS Systèmes d'Information
  2.  * Licensed to CS Systèmes d'Information (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.estimation.measurements.generation;

  18. import org.hipparchus.geometry.euclidean.threed.Vector3D;
  19. import org.hipparchus.random.CorrelatedRandomVectorGenerator;
  20. import org.orekit.estimation.measurements.EstimationModifier;
  21. import org.orekit.estimation.measurements.ObservableSatellite;
  22. import org.orekit.estimation.measurements.PV;
  23. import org.orekit.propagation.SpacecraftState;
  24. import org.orekit.time.AbsoluteDate;
  25. import org.orekit.utils.ParameterDriver;


  26. /** Builder for {@link PV} measurements.
  27.  * @author Luc Maisonobe
  28.  * @since 9.3
  29.  */
  30. public class PVBuilder extends AbstractMeasurementBuilder<PV> {

  31.     /** Simple constructor.
  32.      * @param noiseSource noise source, may be null for generating perfect measurements
  33.      * @param sigmaPosition theoretical standard deviation on position components
  34.      * @param sigmaVelocity theoretical standard deviation on velocity components
  35.      * @param baseWeight base weight
  36.      * @param satellite satellite related to this builder
  37.      */
  38.     public PVBuilder(final CorrelatedRandomVectorGenerator noiseSource,
  39.                      final double sigmaPosition, final double sigmaVelocity,
  40.                      final double baseWeight, final ObservableSatellite satellite) {
  41.         super(noiseSource,
  42.               new double[] {
  43.                   sigmaPosition, sigmaVelocity
  44.               }, new double[] {
  45.                   baseWeight
  46.               }, satellite);
  47.     }

  48.     /** {@inheritDoc} */
  49.     @Override
  50.     public PV build(final SpacecraftState[] states) {

  51.         final ObservableSatellite satellite = getSatellites()[0];
  52.         final double[] sigma                = getTheoreticalStandardDeviation();
  53.         final double baseWeight             = getBaseWeight()[0];
  54.         final SpacecraftState state         = states[satellite.getPropagatorIndex()];

  55.         // create a dummy measurement
  56.         final PV dummy = new PV(state.getDate(), Vector3D.NaN, Vector3D.NaN,
  57.                                 sigma[0], sigma[1], baseWeight, satellite);
  58.         for (final EstimationModifier<PV> modifier : getModifiers()) {
  59.             dummy.addModifier(modifier);
  60.         }

  61.         // set a reference date for parameters missing one
  62.         for (final ParameterDriver driver : dummy.getParametersDrivers()) {
  63.             if (driver.getReferenceDate() == null) {
  64.                 final AbsoluteDate start = getStart();
  65.                 final AbsoluteDate end   = getEnd();
  66.                 driver.setReferenceDate(start.durationFrom(end) <= 0 ? start : end);
  67.             }
  68.         }

  69.         // estimate the perfect value of the measurement
  70.         final double[] pv = dummy.estimate(0, 0, states).getEstimatedValue();

  71.         // add the noise
  72.         final double[] noise = getNoise();
  73.         if (noise != null) {
  74.             pv[0] += noise[0];
  75.             pv[1] += noise[1];
  76.             pv[2] += noise[2];
  77.             pv[3] += noise[3];
  78.             pv[4] += noise[4];
  79.             pv[5] += noise[5];
  80.         }

  81.         // generate measurement
  82.         final PV measurement = new PV(state.getDate(),
  83.                                       new Vector3D(pv[0], pv[1], pv[2]), new Vector3D(pv[3], pv[4], pv[5]),
  84.                                       sigma[0], sigma[1], baseWeight, satellite);
  85.         for (final EstimationModifier<PV> modifier : getModifiers()) {
  86.             measurement.addModifier(modifier);
  87.         }
  88.         return measurement;

  89.     }

  90. }