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2020-08-17T08:29:53Z

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<syntaxhighlight lang="java">
public class TwoDirectionsAttitudeLaw {

public static void main(String[] args) throws PatriusException, IOException, URISyntaxException {

// Patrius Dataset initialization (needed for example to get the UTC time
PatriusDataset.addResourcesFromPatriusDataset() ;

// Recovery of the UTC time scale using a "factory" (not to duplicate such unique object)
final TimeScale TUC = TimeScalesFactory.getUTC();

// Date of the orbit given in UTC time scale)
final AbsoluteDate date = new AbsoluteDate("2010-01-01T12:00:00.000", TUC);

// Getting the frame with wich will defined the orbit parameters
// As for time scale, we will use also a "factory".
final Frame GCRF = FramesFactory.getGCRF();

// Initial orbit
final double sma = 7200.e+3;
final double exc = 0.01;
final double inc = FastMath.toRadians(98.);
final double pa = FastMath.toRadians(0.);
final double raan = FastMath.toRadians(0.);
final double anm = FastMath.toRadians(0.);
final double MU = Constants.WGS84_EARTH_MU;

final KeplerianParameters par = new KeplerianParameters(sma, exc, inc, pa, raan, anm, PositionAngle.MEAN, MU);
final Orbit iniOrbit = new KeplerianOrbit(par, GCRF, date);

// Using the Meeus model for the Sun.
final CelestialBody sun = new MeeusSun();

// Sun directions
ToCelestialBodyCenterDirection dirSun = new ToCelestialBodyCenterDirection(sun);
CelestialBodyPolesAxisDirection dirPole = new CelestialBodyPolesAxisDirection(sun);

// Building an attitude law
final Vector3D firstAxis = new Vector3D(1., 0., 0.);
final Vector3D secondAxis = new Vector3D(0., 1., 0.);
final AttitudeLaw attitudeLaw = new TwoDirectionsAttitude(dirSun, dirPole, firstAxis, secondAxis);
final Attitude att = attitudeLaw.getAttitude(iniOrbit);

// Printing attitude
final double psi = att.getRotation().getAngles(RotationOrder.ZYX)[0];
final double teta = att.getRotation().getAngles(RotationOrder.ZYX)[1];

System.out.println("Psi / GCRF = "+FastMath.toDegrees(psi)+" deg");
System.out.println("Teta / GCRF = "+FastMath.toDegrees(teta)+" deg");

// Coordinates of the Sun vs GCRF at the same date
PVCoordinates pv = sun.getPVCoordinates(date, GCRF);
final Vector3D sunPos = pv.getPosition();

// Direction of the Sun from the cdg of the satellite
final Vector3D satPos = iniOrbit.getPVCoordinates(GCRF).getPosition();
final Rotation sunDir = new Rotation(Vector3D.PLUS_I, sunPos.subtract(satPos));

final double psiSun = sunDir.getAngles(RotationOrder.ZYX)[0];
final double tetaSun = sunDir.getAngles(RotationOrder.ZYX)[1];

System.out.println();
System.out.println("Psi / GCRF = "+FastMath.toDegrees(psiSun)+" deg");
System.out.println("Teta / GCRF = "+FastMath.toDegrees(tetaSun)+" deg");

System.out.println();
System.out.println("Delta Psi = "+FastMath.toDegrees(psiSun-psi)+" deg");
System.out.println("Delta Teta = "+FastMath.toDegrees(tetaSun-teta)+" deg");

}

}
</syntaxhighlight>

TwoDirectionsAttitudeLaw 4.5.1 - Historique des versions

Admin : Page créée avec « public class TwoDirectionsAttitudeLaw { public static void main(String[] args) throws PatriusException, IOException, URISyntaxException... »

Admin : Page créée avec « public class TwoDirectionsAttitudeLaw { public static void main(String[] args) throws PatriusException, IOException, URISyntaxException... »