/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (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 org.hipparchus.geometry.euclidean.threed.Rotation;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.hipparchus.util.FastMath;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.orekit.Utils;
import org.orekit.bodies.CelestialBodyFactory;
import org.orekit.errors.OrekitException;
import org.orekit.frames.Frame;
import org.orekit.frames.FramesFactory;
import org.orekit.orbits.KeplerianOrbit;
import org.orekit.orbits.Orbit;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.DateComponents;
import org.orekit.time.TimeComponents;
import org.orekit.time.TimeScalesFactory;
import org.orekit.utils.PVCoordinates;
import org.orekit.utils.PVCoordinatesProvider;
public class CelestialBodyPointingTest {
@Test
public void testSunPointing() throws OrekitException {
PVCoordinatesProvider sun = CelestialBodyFactory.getSun();
final Frame frame = FramesFactory.getGCRF();
AbsoluteDate date = new AbsoluteDate(new DateComponents(1970, 01, 01),
new TimeComponents(3, 25, 45.6789),
TimeScalesFactory.getTAI());
AttitudeProvider sunPointing =
new CelestialBodyPointed(frame, sun, Vector3D.PLUS_K,
Vector3D.PLUS_I, Vector3D.PLUS_K);
PVCoordinates pv =
new PVCoordinates(new Vector3D(28812595.32120171334, 5948437.45881852374, 0.0),
new Vector3D(0, 0, 3680.853673522056));
Orbit orbit = new KeplerianOrbit(pv, frame, date, 3.986004415e14);
Attitude attitude = sunPointing.getAttitude(orbit, date, frame);
Vector3D xDirection = attitude.getRotation().applyInverseTo(Vector3D.PLUS_I);
Vector3D zDirection = attitude.getRotation().applyInverseTo(Vector3D.PLUS_K);
Assert.assertEquals(0,
Vector3D.dotProduct(zDirection, Vector3D.crossProduct(xDirection, Vector3D.PLUS_K)),
1.0e-15);
// the following statement checks we take parallax into account
// Sun-Earth-Sat are in quadrature, with distance (Earth, Sat) == distance(Sun, Earth) / 5000
Assert.assertEquals(FastMath.atan(1.0 / 5000.0),
Vector3D.angle(xDirection,
sun.getPVCoordinates(date, frame).getPosition()),
1.0e-15);
double h = 0.1;
Attitude aMinus = sunPointing.getAttitude(orbit.shiftedBy(-h), date.shiftedBy(-h), frame);
Attitude a0 = sunPointing.getAttitude(orbit, date, frame);
Attitude aPlus = sunPointing.getAttitude(orbit.shiftedBy(h), date.shiftedBy(h), frame);
// check spin is consistent with attitude evolution
double errorAngleMinus = Rotation.distance(aMinus.shiftedBy(h).getRotation(),
a0.getRotation());
double evolutionAngleMinus = Rotation.distance(aMinus.getRotation(),
a0.getRotation());
Assert.assertEquals(0.0, errorAngleMinus, 1.0e-6 * evolutionAngleMinus);
double errorAnglePlus = Rotation.distance(a0.getRotation(),
aPlus.shiftedBy(-h).getRotation());
double evolutionAnglePlus = Rotation.distance(a0.getRotation(),
aPlus.getRotation());
Assert.assertEquals(0.0, errorAnglePlus, 1.0e-6 * evolutionAnglePlus);
}
@Before
public void setUp() {
Utils.setDataRoot("regular-data");
}
}