Examples with Propagator org.orekit.propagation.Propagator used on opensource projects

Example 91 with Propagator

use of org.orekit.propagation.Propagator in project Orekit by CS-SI.

the class AttitudesSequenceTest method testBackwardPropagation.

@Test
public void testBackwardPropagation() throws OrekitException {
    // Initial state definition : date, orbit
    final AbsoluteDate initialDate = new AbsoluteDate(2004, 01, 01, 23, 30, 00.000, TimeScalesFactory.getUTC());
    final Vector3D position = new Vector3D(-6142438.668, 3492467.560, -25767.25680);
    final Vector3D velocity = new Vector3D(505.8479685, 942.7809215, 7435.922231);
    final Orbit initialOrbit = new KeplerianOrbit(new PVCoordinates(position, velocity), FramesFactory.getEME2000(), initialDate, Constants.EIGEN5C_EARTH_MU);
    final AttitudesSequence attitudesSequence = new AttitudesSequence();
    final AttitudeProvider past = new InertialProvider(Rotation.IDENTITY);
    final AttitudeProvider current = new InertialProvider(Rotation.IDENTITY);
    final AttitudeProvider future = new InertialProvider(Rotation.IDENTITY);
    final Handler handler = new Handler(current, past);
    attitudesSequence.addSwitchingCondition(past, current, new DateDetector(initialDate.shiftedBy(-500.0)), true, false, 10.0, AngularDerivativesFilter.USE_R, handler);
    attitudesSequence.addSwitchingCondition(current, future, new DateDetector(initialDate.shiftedBy(+500.0)), true, false, 10.0, AngularDerivativesFilter.USE_R, null);
    attitudesSequence.resetActiveProvider(current);
    SpacecraftState initialState = new SpacecraftState(initialOrbit);
    initialState = initialState.addAdditionalState("fortyTwo", 42.0);
    final Propagator propagator = new EcksteinHechlerPropagator(initialOrbit, attitudesSequence, Constants.EIGEN5C_EARTH_EQUATORIAL_RADIUS, Constants.EIGEN5C_EARTH_MU, Constants.EIGEN5C_EARTH_C20, Constants.EIGEN5C_EARTH_C30, Constants.EIGEN5C_EARTH_C40, Constants.EIGEN5C_EARTH_C50, Constants.EIGEN5C_EARTH_C60);
    propagator.resetInitialState(initialState);
    Assert.assertEquals(42.0, propagator.getInitialState().getAdditionalState("fortyTwo")[0], 1.0e-10);
    // Register the switching events to the propagator
    attitudesSequence.registerSwitchEvents(propagator);
    SpacecraftState finalState = propagator.propagate(initialDate.shiftedBy(-10000.0));
    Assert.assertEquals(42.0, finalState.getAdditionalState("fortyTwo")[0], 1.0e-10);
    Assert.assertEquals(1, handler.dates.size());
    Assert.assertEquals(-500.0, handler.dates.get(0).durationFrom(initialDate), 1.0e-3);
    Assert.assertEquals(-490.0, finalState.getDate().durationFrom(initialDate), 1.0e-3);
}

Example 92 with Propagator

use of org.orekit.propagation.Propagator in project SpriteOrbits by ProjectPersephone.

the class SpriteProp method run.

/**
 * run the application.
 * @param out output file
 * @param propagationDuration duration of the propagation
 * @param step fixed step between output lines
 * @param utc UTC time scale
 */
public void run(final PrintStream out, final double propagationDuration, final double step, final TimeScale utc) throws OrekitException {
    final AbsoluteDate start = spritesPropagators.get(0).getInitialState().getDate();
    final AbsoluteDate end = start.shiftedBy(propagationDuration * Constants.JULIAN_DAY);
    /*out.format(Locale.US, "# file generated on %s%n",
                   new AbsoluteDate(new Date(), utc).toString(utc));
        out.format(Locale.US, "# propagating %d sprites from %s to %s%n",
                   spritesPropagators.size(), start.toString(utc), end.toString(utc));
        out.format(Locale.US, "# column 1:    date (UTC)%n");
        out.format(Locale.US, "# column 2:    date offset since start (seconds)%n");
        out.format(Locale.US, "# column 3:    KickSat geodetic latitude (degrees)%n");
        out.format(Locale.US, "# column 4:    KickSat geodetic longitude (degrees)%n");
        out.format(Locale.US, "# column 5:    KickSat geodetic altitude (meters)%n");
        out.format(Locale.US, "# column 3i+3: sprite i geodetic latitude (degrees)%n");
        out.format(Locale.US, "# column 3i+4: sprite i geodetic longitude (degrees)%n");
        out.format(Locale.US, "# column 3i+5: sprite i geodetic altitude (meters)%n");
        */
    // in order to speed up computation, we let the numerical propagator choose its
    // steps, and create ephemerides, then we will use the ephemerides with fixed
    // steps for output
    List<Propagator> ephemerides = new ArrayList<Propagator>(spritesPropagators.size());
    for (final Propagator spritePropagator : spritesPropagators) {
        spritePropagator.setEphemerisMode();
        spritePropagator.propagate(end);
        ephemerides.add(spritePropagator.getGeneratedEphemeris());
    }
    boolean firstTime = true;
    for (AbsoluteDate date = start; date.compareTo(end) < 0; date = date.shiftedBy(step)) {
        if (!firstTime) {
            out.format(Locale.US, ",");
        } else {
            firstTime = false;
        }
        /*out.format(Locale.US, "%s %9.1f", date.toString(utc), date.durationFrom(start));

            final GeodeticPoint kickSatGP = geodeticPosition(kickSatPropagator, date);
            out.format(Locale.US, " %8.3f %8.3f %8.1f",
                       FastMath.toDegrees(kickSatGP.getLatitude()),
                       FastMath.toDegrees(kickSatGP.getLongitude()),
                       kickSatGP.getAltitude());

            for (final Propagator ephemeride : ephemerides) {
                final GeodeticPoint spriteGP = geodeticPosition(ephemeride, date);
                out.format(Locale.US, " %8.3f %8.3f %8.1f",
                           FastMath.toDegrees(spriteGP.getLatitude()),
                           FastMath.toDegrees(spriteGP.getLongitude()),
                           spriteGP.getAltitude());
            }
            */
        out.format(Locale.US, "{\"date\":\"%s\",\"offset\":%.1f,", date.toString(utc), date.durationFrom(start));
        final GeodeticPoint kickSatGP = geodeticPosition(kickSatPropagator, date);
        out.format(Locale.US, "\"kicksat\":{\"lat\":%.3f,\"lng\":%.3f,\"alt\":%.1f},", FastMath.toDegrees(kickSatGP.getLatitude()), FastMath.toDegrees(kickSatGP.getLongitude()), kickSatGP.getAltitude());
        out.format(Locale.US, "\"sprites\":[");
        boolean firstSprite = true;
        for (final Propagator ephemeride : ephemerides) {
            final GeodeticPoint spriteGP = geodeticPosition(ephemeride, date);
            if (!firstSprite) {
                out.format(Locale.US, ",");
            } else {
                firstSprite = false;
            }
            out.format(Locale.US, "{\"lat\":%.3f,\"lng\":%.3f,\"alt\":%.1f}", FastMath.toDegrees(spriteGP.getLatitude()), FastMath.toDegrees(spriteGP.getLongitude()), spriteGP.getAltitude());
        }
        out.format(Locale.US, "]}");
        out.println();
    }
}

Example 93 with Propagator

use of org.orekit.propagation.Propagator in project SpriteOrbits by ProjectPersephone.

the class SpritePropOrig method run.

/**
 * run the application.
 * @param out output file
 * @param propagationDuration duration of the propagation
 * @param step fixed step between output lines
 * @param utc UTC time scale
 */
public void run(final PrintStream out, final double propagationDuration, final double step, final TimeScale utc) throws OrekitException {
    final AbsoluteDate start = spritesPropagators.get(0).getInitialState().getDate();
    final AbsoluteDate end = start.shiftedBy(propagationDuration * Constants.JULIAN_DAY);
    out.format(Locale.US, "# file generated on %s%n", new AbsoluteDate(new Date(), utc).toString(utc));
    out.format(Locale.US, "# propagating %d sprites from %s to %s%n", spritesPropagators.size(), start.toString(utc), end.toString(utc));
    out.format(Locale.US, "# column 1:    date (UTC)%n");
    out.format(Locale.US, "# column 2:    date offset since start (seconds)%n");
    out.format(Locale.US, "# column 3:    KickSat geodetic latitude (degrees)%n");
    out.format(Locale.US, "# column 4:    KickSat geodetic longitude (degrees)%n");
    out.format(Locale.US, "# column 5:    KickSat geodetic altitude (meters)%n");
    out.format(Locale.US, "# column 3i+3: sprite i geodetic latitude (degrees)%n");
    out.format(Locale.US, "# column 3i+4: sprite i geodetic longitude (degrees)%n");
    out.format(Locale.US, "# column 3i+5: sprite i geodetic altitude (meters)%n");
    // in order to speed up computation, we let the numerical propagator choose its
    // steps, and create ephemerides, then we will use the ephemerides with fixed
    // steps for output
    List<Propagator> ephemerides = new ArrayList<Propagator>(spritesPropagators.size());
    for (final Propagator spritePropagator : spritesPropagators) {
        spritePropagator.setEphemerisMode();
        spritePropagator.propagate(end);
        ephemerides.add(spritePropagator.getGeneratedEphemeris());
    }
    for (AbsoluteDate date = start; date.compareTo(end) < 0; date = date.shiftedBy(step)) {
        out.format(Locale.US, "%s %9.1f", date.toString(utc), date.durationFrom(start));
        final GeodeticPoint kickSatGP = geodeticPosition(kickSatPropagator, date);
        out.format(Locale.US, " %8.3f %8.3f %8.1f", FastMath.toDegrees(kickSatGP.getLatitude()), FastMath.toDegrees(kickSatGP.getLongitude()), kickSatGP.getAltitude());
        for (final Propagator ephemeride : ephemerides) {
            final GeodeticPoint spriteGP = geodeticPosition(ephemeride, date);
            out.format(Locale.US, " %8.3f %8.3f %8.1f", FastMath.toDegrees(spriteGP.getLatitude()), FastMath.toDegrees(spriteGP.getLongitude()), spriteGP.getAltitude());
        }
        out.println();
    }
}

Example 94 with Propagator

use of org.orekit.propagation.Propagator in project Orekit by CS-SI.

the class DOPComputer method compute.

/**
 * Compute the {@link DOP} at a given date for a set of GNSS spacecrafts.
 * <p>Four GNSS spacecraft at least are needed to compute the DOP.
 * If less than 4 propagators are provided, an exception will be thrown.
 * If less than 4 spacecrafts are visible at the date, all DOP values will be
 * set to {@link java.lang.Double#NaN NaN}.</p>
 *
 * @param date the computation date
 * @param gnss the propagators for GNSS spacecraft involved in the DOP computation
 * @return the {@link DOP} at the location
 * @throws OrekitException if something wrong occurs
 */
public DOP compute(final AbsoluteDate date, final List<Propagator> gnss) throws OrekitException {
    // Checks the number of provided propagators
    if (gnss.size() < DOP_MIN_PROPAGATORS) {
        throw new OrekitException(OrekitMessages.NOT_ENOUGH_GNSS_FOR_DOP, gnss.size(), DOP_MIN_PROPAGATORS);
    }
    // Initializes DOP values
    double gdop = Double.NaN;
    double pdop = Double.NaN;
    double hdop = Double.NaN;
    double vdop = Double.NaN;
    double tdop = Double.NaN;
    // Loop over the propagators of GNSS orbits
    final double[][] satDir = new double[gnss.size()][4];
    int satNb = 0;
    for (Propagator prop : gnss) {
        final Vector3D pos = prop.getPVCoordinates(date, frame).getPosition();
        final double elev = frame.getElevation(pos, frame, date);
        final double elMin = (elevationMask != null) ? elevationMask.getElevation(frame.getAzimuth(pos, frame, date)) : minElevation;
        // Only visible satellites are considered
        if (elev > elMin) {
            // Create the rows of the H matrix
            final Vector3D r = pos.normalize();
            satDir[satNb][0] = r.getX();
            satDir[satNb][1] = r.getY();
            satDir[satNb][2] = r.getZ();
            satDir[satNb][3] = -1.;
            satNb++;
        }
    }
    // DOP values are computed only if at least 4 SV are visible from the location
    if (satNb > 3) {
        // Construct matrix H
        final RealMatrix h = MatrixUtils.createRealMatrix(satNb, 4);
        for (int k = 0; k < satNb; k++) {
            h.setRow(k, satDir[k]);
        }
        // Compute the pseudo-inverse of H
        final RealMatrix hInv = MatrixUtils.inverse(h.transpose().multiply(h));
        final double sx2 = hInv.getEntry(0, 0);
        final double sy2 = hInv.getEntry(1, 1);
        final double sz2 = hInv.getEntry(2, 2);
        final double st2 = hInv.getEntry(3, 3);
        // Extract various DOP : GDOP, PDOP, HDOP, VDOP, TDOP
        gdop = FastMath.sqrt(hInv.getTrace());
        pdop = FastMath.sqrt(sx2 + sy2 + sz2);
        hdop = FastMath.sqrt(sx2 + sy2);
        vdop = FastMath.sqrt(sz2);
        tdop = FastMath.sqrt(st2);
    }
    // Return all the DOP values
    return new DOP(frame.getPoint(), date, satNb, gdop, pdop, hdop, vdop, tdop);
}

Example 95 with Propagator

use of org.orekit.propagation.Propagator in project Orekit by CS-SI.

the class OsculatingToMeanElementsConverter method convert.

/**
 * Convert an osculating orbit into a mean orbit, in DSST sense.
 *  @return mean orbit state, in DSST sense
 *  @throws OrekitException if state cannot be propagated throughout range
 */
public final SpacecraftState convert() throws OrekitException {
    final double timeSpan = state.getKeplerianPeriod() * satelliteRevolution;
    propagator.resetInitialState(state);
    final FiniteDifferencePropagatorConverter converter = new FiniteDifferencePropagatorConverter(new KeplerianPropagatorBuilder(state.getOrbit(), PositionAngle.MEAN, positionScale), 1.e-6, MAX_EVALUATION);
    final Propagator prop = converter.convert(propagator, timeSpan, satelliteRevolution * 36);
    return prop.getInitialState();
}