List of usage examples for org.apache.commons.math3.geometry.euclidean.threed Rotation IDENTITY
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From source file:org.orekit.utils.AngularCoordinatesTest.java
@Test public void testShiftWithoutAcceleration() throws OrekitException { double rate = 2 * FastMath.PI / (12 * 60); AngularCoordinates ac = new AngularCoordinates(Rotation.IDENTITY, new Vector3D(rate, Vector3D.PLUS_K), Vector3D.ZERO);//w w w.j a v a2 s.c o m Assert.assertEquals(rate, ac.getRotationRate().getNorm(), 1.0e-10); double dt = 10.0; double alpha = rate * dt; AngularCoordinates shifted = ac.shiftedBy(dt); Assert.assertEquals(rate, shifted.getRotationRate().getNorm(), 1.0e-10); Assert.assertEquals(alpha, Rotation.distance(ac.getRotation(), shifted.getRotation()), 1.0e-15); Vector3D xSat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_I); Assert.assertEquals(0.0, xSat.subtract(new Vector3D(FastMath.cos(alpha), FastMath.sin(alpha), 0)).getNorm(), 1.0e-15); Vector3D ySat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_J); Assert.assertEquals(0.0, ySat.subtract(new Vector3D(-FastMath.sin(alpha), FastMath.cos(alpha), 0)).getNorm(), 1.0e-15); Vector3D zSat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_K); Assert.assertEquals(0.0, zSat.subtract(Vector3D.PLUS_K).getNorm(), 1.0e-15); }
From source file:org.orekit.utils.AngularCoordinatesTest.java
@Test public void testShiftWithAcceleration() throws OrekitException { double rate = 2 * FastMath.PI / (12 * 60); double acc = 0.001; double dt = 1.0; int n = 2000; final AngularCoordinates quadratic = new AngularCoordinates(Rotation.IDENTITY, new Vector3D(rate, Vector3D.PLUS_K), new Vector3D(acc, Vector3D.PLUS_J)); final AngularCoordinates linear = new AngularCoordinates(quadratic.getRotation(), quadratic.getRotationRate(), Vector3D.ZERO); final FirstOrderDifferentialEquations ode = new FirstOrderDifferentialEquations() { public int getDimension() { return 4; }//from ww w .ja v a 2 s .c o m public void computeDerivatives(final double t, final double[] q, final double[] qDot) { final double omegaX = quadratic.getRotationRate().getX() + t * quadratic.getRotationAcceleration().getX(); final double omegaY = quadratic.getRotationRate().getY() + t * quadratic.getRotationAcceleration().getY(); final double omegaZ = quadratic.getRotationRate().getZ() + t * quadratic.getRotationAcceleration().getZ(); qDot[0] = 0.5 * MathArrays.linearCombination(-q[1], omegaX, -q[2], omegaY, -q[3], omegaZ); qDot[1] = 0.5 * MathArrays.linearCombination(q[0], omegaX, -q[3], omegaY, q[2], omegaZ); qDot[2] = 0.5 * MathArrays.linearCombination(q[3], omegaX, q[0], omegaY, -q[1], omegaZ); qDot[3] = 0.5 * MathArrays.linearCombination(-q[2], omegaX, q[1], omegaY, q[0], omegaZ); } }; FirstOrderIntegrator integrator = new DormandPrince853Integrator(1.0e-6, 1.0, 1.0e-12, 1.0e-12); integrator.addStepHandler(new StepNormalizer(dt / n, new FixedStepHandler() { public void init(double t0, double[] y0, double t) { } public void handleStep(double t, double[] y, double[] yDot, boolean isLast) { Rotation reference = new Rotation(y[0], y[1], y[2], y[3], true); // the error in shiftedBy taking acceleration into account is cubic double expectedCubicError = 1.4544e-6 * t * t * t; Assert.assertEquals(expectedCubicError, Rotation.distance(reference, quadratic.shiftedBy(t).getRotation()), 0.0001 * expectedCubicError); // the error in shiftedBy not taking acceleration into account is quadratic double expectedQuadraticError = 5.0e-4 * t * t; Assert.assertEquals(expectedQuadraticError, Rotation.distance(reference, linear.shiftedBy(t).getRotation()), 0.00001 * expectedQuadraticError); } })); double[] y = new double[] { quadratic.getRotation().getQ0(), quadratic.getRotation().getQ1(), quadratic.getRotation().getQ2(), quadratic.getRotation().getQ3() }; integrator.integrate(ode, 0, y, dt, y); }
From source file:org.orekit.utils.AngularCoordinatesTest.java
@Test public void testRodriguesSpecialCases() { // identity/* w w w . j av a 2 s .co m*/ double[][] identity = new AngularCoordinates(Rotation.IDENTITY, Vector3D.ZERO, Vector3D.ZERO) .getModifiedRodrigues(1.0); for (double[] row : identity) { for (double element : row) { Assert.assertEquals(0.0, element, Precision.SAFE_MIN); } } AngularCoordinates acId = AngularCoordinates.createFromModifiedRodrigues(identity); Assert.assertEquals(0.0, acId.getRotation().getAngle(), Precision.SAFE_MIN); Assert.assertEquals(0.0, acId.getRotationRate().getNorm(), Precision.SAFE_MIN); // PI angle rotation (which is singular for non-modified Rodrigues vector) RandomGenerator random = new Well1024a(0x2158523e6accb859l); for (int i = 0; i < 100; ++i) { Vector3D axis = randomVector(random, 1.0); AngularCoordinates original = new AngularCoordinates(new Rotation(axis, FastMath.PI), Vector3D.ZERO, Vector3D.ZERO); AngularCoordinates rebuilt = AngularCoordinates .createFromModifiedRodrigues(original.getModifiedRodrigues(1.0)); Assert.assertEquals(FastMath.PI, rebuilt.getRotation().getAngle(), 1.0e-15); Assert.assertEquals(0.0, FastMath.sin(Vector3D.angle(axis, rebuilt.getRotation().getAxis())), 1.0e-15); Assert.assertEquals(0.0, rebuilt.getRotationRate().getNorm(), 1.0e-16); } }
From source file:org.orekit.utils.TimeStampedAngularCoordinates.java
/** Interpolate angular coordinates. * <p>/*from ww w . ja va2 s .c om*/ * The interpolated instance is created by polynomial Hermite interpolation * on Rodrigues vector ensuring rotation rate remains the exact derivative of rotation. * </p> * <p> * This method is based on Sergei Tanygin's paper <a * href="http://www.agi.com/downloads/resources/white-papers/Attitude-interpolation.pdf">Attitude * Interpolation</a>, changing the norm of the vector to match the modified Rodrigues * vector as described in Malcolm D. Shuster's paper <a * href="http://www.ladispe.polito.it/corsi/Meccatronica/02JHCOR/2011-12/Slides/Shuster_Pub_1993h_J_Repsurv_scan.pdf">A * Survey of Attitude Representations</a>. This change avoids the singularity at . * There is still a singularity at 2, which is handled by slightly offsetting all rotations * when this singularity is detected. * </p> * <p> * Note that even if first and second time derivatives (rotation rates and acceleration) * from sample can be ignored, the interpolated instance always includes * interpolated derivatives. This feature can be used explicitly to * compute these derivatives when it would be too complex to compute them * from an analytical formula: just compute a few sample points from the * explicit formula and set the derivatives to zero in these sample points, * then use interpolation to add derivatives consistent with the rotations. * </p> * @param date interpolation date * @param filter filter for derivatives from the sample to use in interpolation * @param sample sample points on which interpolation should be done * @return a new position-velocity, interpolated at specified date * @exception OrekitException if the number of point is too small for interpolating */ public static TimeStampedAngularCoordinates interpolate(final AbsoluteDate date, final AngularDerivativesFilter filter, final Collection<TimeStampedAngularCoordinates> sample) throws OrekitException { // set up safety elements for 2 singularity avoidance final double epsilon = 2 * FastMath.PI / sample.size(); final double threshold = FastMath.min(-(1.0 - 1.0e-4), -FastMath.cos(epsilon / 4)); // set up a linear model canceling mean rotation rate final Vector3D meanRate; if (filter != AngularDerivativesFilter.USE_R) { Vector3D sum = Vector3D.ZERO; for (final TimeStampedAngularCoordinates datedAC : sample) { sum = sum.add(datedAC.getRotationRate()); } meanRate = new Vector3D(1.0 / sample.size(), sum); } else { if (sample.size() < 2) { throw new OrekitException(OrekitMessages.NOT_ENOUGH_DATA_FOR_INTERPOLATION, sample.size()); } Vector3D sum = Vector3D.ZERO; TimeStampedAngularCoordinates previous = null; for (final TimeStampedAngularCoordinates datedAC : sample) { if (previous != null) { sum = sum.add(estimateRate(previous.getRotation(), datedAC.getRotation(), datedAC.date.durationFrom(previous.date))); } previous = datedAC; } meanRate = new Vector3D(1.0 / (sample.size() - 1), sum); } TimeStampedAngularCoordinates offset = new TimeStampedAngularCoordinates(date, Rotation.IDENTITY, meanRate, Vector3D.ZERO); boolean restart = true; for (int i = 0; restart && i < sample.size() + 2; ++i) { // offset adaptation parameters restart = false; // set up an interpolator taking derivatives into account final HermiteInterpolator interpolator = new HermiteInterpolator(); // add sample points double sign = +1.0; Rotation previous = Rotation.IDENTITY; for (final TimeStampedAngularCoordinates ac : sample) { // remove linear offset from the current coordinates final double dt = ac.date.durationFrom(date); final TimeStampedAngularCoordinates fixed = ac.subtractOffset(offset.shiftedBy(dt)); // make sure all interpolated points will be on the same branch final double dot = MathArrays.linearCombination(fixed.getRotation().getQ0(), previous.getQ0(), fixed.getRotation().getQ1(), previous.getQ1(), fixed.getRotation().getQ2(), previous.getQ2(), fixed.getRotation().getQ3(), previous.getQ3()); sign = FastMath.copySign(1.0, dot * sign); previous = fixed.getRotation(); // check modified Rodrigues vector singularity if (fixed.getRotation().getQ0() * sign < threshold) { // the sample point is close to a modified Rodrigues vector singularity // we need to change the linear offset model to avoid this restart = true; break; } final double[][] rodrigues = fixed.getModifiedRodrigues(sign); switch (filter) { case USE_RRA: // populate sample with rotation, rotation rate and acceleration data interpolator.addSamplePoint(dt, rodrigues[0], rodrigues[1], rodrigues[2]); break; case USE_RR: // populate sample with rotation and rotation rate data interpolator.addSamplePoint(dt, rodrigues[0], rodrigues[1]); break; case USE_R: // populate sample with rotation data only interpolator.addSamplePoint(dt, rodrigues[0]); break; default: // this should never happen throw new OrekitInternalError(null); } } if (restart) { // interpolation failed, some intermediate rotation was too close to 2 // we need to offset all rotations to avoid the singularity offset = offset.addOffset(new AngularCoordinates(new Rotation(Vector3D.PLUS_I, epsilon), Vector3D.ZERO, Vector3D.ZERO)); } else { // interpolation succeeded with the current offset final DerivativeStructure zero = new DerivativeStructure(1, 2, 0, 0.0); final DerivativeStructure[] p = interpolator.value(zero); final AngularCoordinates ac = createFromModifiedRodrigues( new double[][] { { p[0].getValue(), p[1].getValue(), p[2].getValue() }, { p[0].getPartialDerivative(1), p[1].getPartialDerivative(1), p[2].getPartialDerivative(1) }, { p[0].getPartialDerivative(2), p[1].getPartialDerivative(2), p[2].getPartialDerivative(2) } }); return new TimeStampedAngularCoordinates(offset.getDate(), ac.getRotation(), ac.getRotationRate(), ac.getRotationAcceleration()).addOffset(offset); } } // this should never happen throw new OrekitInternalError(null); }
From source file:org.orekit.utils.TimeStampedAngularCoordinatesTest.java
@Test public void testShift() throws OrekitException { double rate = 2 * FastMath.PI / (12 * 60); TimeStampedAngularCoordinates ac = new TimeStampedAngularCoordinates(AbsoluteDate.J2000_EPOCH, Rotation.IDENTITY, new Vector3D(rate, Vector3D.PLUS_K), Vector3D.ZERO); Assert.assertEquals(rate, ac.getRotationRate().getNorm(), 1.0e-10); double dt = 10.0; double alpha = rate * dt; TimeStampedAngularCoordinates shifted = ac.shiftedBy(dt); Assert.assertEquals(rate, shifted.getRotationRate().getNorm(), 1.0e-10); Assert.assertEquals(alpha, Rotation.distance(ac.getRotation(), shifted.getRotation()), 1.0e-10); Vector3D xSat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_I); Assert.assertEquals(0.0, xSat.subtract(new Vector3D(FastMath.cos(alpha), FastMath.sin(alpha), 0)).getNorm(), 1.0e-10);/* w ww . j a v a 2 s. c o m*/ Vector3D ySat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_J); Assert.assertEquals(0.0, ySat.subtract(new Vector3D(-FastMath.sin(alpha), FastMath.cos(alpha), 0)).getNorm(), 1.0e-10); Vector3D zSat = shifted.getRotation().applyInverseTo(Vector3D.PLUS_K); Assert.assertEquals(0.0, zSat.subtract(Vector3D.PLUS_K).getNorm(), 1.0e-10); }
From source file:org.orekit.utils.TimeStampedAngularCoordinatesTest.java
@Test public void testInterpolationNeedOffsetWrongRate() throws OrekitException { AbsoluteDate date = AbsoluteDate.GALILEO_EPOCH; double omega = 2.0 * FastMath.PI; TimeStampedAngularCoordinates reference = new TimeStampedAngularCoordinates(date, Rotation.IDENTITY, new Vector3D(omega, Vector3D.MINUS_K), Vector3D.ZERO); List<TimeStampedAngularCoordinates> sample = new ArrayList<TimeStampedAngularCoordinates>(); for (double dt : new double[] { 0.0, 0.25, 0.5, 0.75, 1.0 }) { TimeStampedAngularCoordinates shifted = reference.shiftedBy(dt); sample.add(new TimeStampedAngularCoordinates(shifted.getDate(), shifted.getRotation(), Vector3D.ZERO, Vector3D.ZERO));/*from ww w. jav a 2 s . c o m*/ } for (TimeStampedAngularCoordinates s : sample) { TimeStampedAngularCoordinates interpolated = TimeStampedAngularCoordinates.interpolate(s.getDate(), AngularDerivativesFilter.USE_RR, sample); Rotation r = interpolated.getRotation(); Vector3D rate = interpolated.getRotationRate(); Assert.assertEquals(0.0, Rotation.distance(s.getRotation(), r), 2.0e-14); Assert.assertEquals(0.0, Vector3D.distance(s.getRotationRate(), rate), 2.0e-13); } }