fsfw/coordinates/CoordinateTransformations.cpp

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#include <framework/coordinates/CoordinateTransformations.h>
#include <framework/globalfunctions/constants.h>
#include <framework/globalfunctions/math/MatrixOperations.h>
#include <framework/globalfunctions/math/VectorOperations.h>
#include <stddef.h>
#include <cmath>
//TODO move time stuff to OSAL
void CoordinateTransformations::positionEcfToEci(const double* ecfPosition,
double* eciPosition) {
ecfToEci(ecfPosition, eciPosition, NULL);
}
void CoordinateTransformations::velocityEcfToEci(const double* ecfVelocity,
const double* ecfPosition, double* eciVelocity) {
ecfToEci(ecfVelocity, eciVelocity, ecfPosition);
}
double CoordinateTransformations::getEarthRotationAngle(timeval time) {
double jD2000UTC = (time.tv_sec - 946728000. + time.tv_usec / 1000000.)
/ 24. / 3600.;
//value of unix time at J2000TT
static const double J2000TtUnix = 946727935.816;
//TT does not have leap seconds
//so we need to add the leap seconds since J2000 to our UTC based clock
//Conveniently, GPS gives us access to the leap seconds since 1980
//between 1980 and 2000 13 leap seconds happened
uint8_t leapSecondsSinceJ2000 = utcGpsOffset - 13;
//Julean centuries since J2000 //TODO fails for dates before now?
double TTt2000 = (time.tv_sec + time.tv_usec / 1000000. - J2000TtUnix
+ leapSecondsSinceJ2000) / 24. / 3600. / 36525.;
double theta = 2 * Math::PI
* (0.779057273264 + 1.00273781191135448 * jD2000UTC);
//Correct theta according to IAU 2000 precession-nutation model
theta = theta + 7.03270725817493E-008 + 0.0223603701 * TTt2000
+ 6.77128219501896E-006 * TTt2000 * TTt2000
+ 4.5300990362875E-010 * TTt2000 * TTt2000 * TTt2000
+ 9.12419347848147E-011 * TTt2000 * TTt2000 * TTt2000 * TTt2000;
return theta;
}
void CoordinateTransformations::getEarthRotationMatrix(timeval time,
double matrix[][3]) {
double theta = getEarthRotationAngle(time);
matrix[0][0] = cos(theta);
matrix[0][1] = sin(theta);
matrix[0][2] = 0;
matrix[1][0] = -sin(theta);
matrix[1][1] = cos(theta);
matrix[1][2] = 0;
matrix[2][0] = 0;
matrix[2][1] = 0;
matrix[2][2] = 1;
}
void CoordinateTransformations::ecfToEci(const double* ecfCoordinates,
double* eciCoordinates,
const double* ecfPositionIfCoordinatesAreVelocity) {
//TODO all calculations only work with a correct time
timeval time;
OSAL::getClock_timeval(&time);
//value of unix time at J2000TT
static const double J2000TtUnix = 946727935.816;
//we need TT which does not have leap seconds
//so we need to add the leap seconds since J2000 to our UTC based clock
//Conveniently, GPS gives us access to the leap seconds since 1980
//between 1980 and 2000 13 leap seconds happened
uint8_t leapSecondsSinceJ2000 = utcGpsOffset - 13;
//Julean centuries since J2000 //TODO fails for dates before now?
double TTt2000 = (time.tv_sec + time.tv_usec / 1000000. - J2000TtUnix
+ leapSecondsSinceJ2000) / 24. / 3600. / 36525.;
//////////////////////////////////////////////////////////
// Calculate Precession Matrix
double zeta = 0.0111808609 * TTt2000
+ 1.46355554053347E-006 * TTt2000 * TTt2000
+ 8.72567663260943E-008 * TTt2000 * TTt2000 * TTt2000;
double theta_p = 0.0097171735 * TTt2000
- 2.06845757045384E-006 * TTt2000 * TTt2000
- 2.02812107218552E-007 * TTt2000 * TTt2000 * TTt2000;
double z = zeta + 3.8436028638364E-006 * TTt2000 * TTt2000
+ 0.000000001 * TTt2000 * TTt2000 * TTt2000;
double mPrecession[3][3];
mPrecession[0][0] = -sin(z) * sin(zeta) + cos(z) * cos(theta_p) * cos(zeta);
mPrecession[1][0] = cos(z) * sin(zeta) + sin(z) * cos(theta_p) * cos(zeta);
mPrecession[2][0] = sin(theta_p) * cos(zeta);
mPrecession[0][1] = -sin(z) * cos(zeta) - cos(z) * cos(theta_p) * sin(zeta);
mPrecession[1][1] = cos(z) * cos(zeta) - sin(z) * cos(theta_p) * sin(zeta);
mPrecession[2][1] = -sin(theta_p) * sin(zeta);
mPrecession[0][2] = -cos(z) * sin(theta_p);
mPrecession[1][2] = -sin(z) * sin(theta_p);
mPrecession[2][2] = cos(theta_p);
//////////////////////////////////////////////////////////
// Calculate Nutation Matrix
double omega_moon = 2.1824386244 - 33.7570459338 * TTt2000
+ 3.61428599267159E-005 * TTt2000 * TTt2000
+ 3.87850944887629E-008 * TTt2000 * TTt2000 * TTt2000;
double deltaPsi = -0.000083388 * sin(omega_moon);
double deltaEpsilon = 4.46174030725106E-005 * cos(omega_moon);
double epsilon = 0.4090928042 - 0.0002269655 * TTt2000
- 2.86040071854626E-009 * TTt2000 * TTt2000
+ 8.78967203851589E-009 * TTt2000 * TTt2000 * TTt2000;
double mNutation[3][3];
mNutation[0][0] = cos(deltaPsi);
mNutation[1][0] = cos(epsilon + deltaEpsilon) * sin(deltaPsi);
mNutation[2][0] = sin(epsilon + deltaEpsilon) * sin(deltaPsi);
mNutation[0][1] = -cos(epsilon) * sin(deltaPsi);
mNutation[1][1] = cos(epsilon) * cos(epsilon + deltaEpsilon) * cos(deltaPsi)
+ sin(epsilon) * sin(epsilon + deltaEpsilon);
mNutation[2][1] = cos(epsilon) * sin(epsilon + deltaEpsilon) * cos(deltaPsi)
- sin(epsilon) * cos(epsilon + deltaEpsilon);
mNutation[0][2] = -sin(epsilon) * sin(deltaPsi);
mNutation[1][2] = sin(epsilon) * cos(epsilon + deltaEpsilon) * cos(deltaPsi)
- cos(epsilon) * sin(epsilon + deltaEpsilon);
mNutation[2][2] = sin(epsilon) * sin(epsilon + deltaEpsilon) * cos(deltaPsi)
+ cos(epsilon) * cos(epsilon + deltaEpsilon);
//////////////////////////////////////////////////////////
// Calculate Earth rotation matrix
//calculate theta
double mTheta[3][3];
getEarthRotationMatrix(time, mTheta);
//polar motion is neglected
double Tfi[3][3];
double Ttemp[3][3];
double Tif[3][3];
MatrixOperations<double>::multiply(mNutation[0], mPrecession[0], Ttemp[0],
3, 3, 3);
MatrixOperations<double>::multiply(mTheta[0], Ttemp[0], Tfi[0], 3, 3, 3);
MatrixOperations<double>::transpose(Tfi[0], Tif[0], 3);
MatrixOperations<double>::multiply(Tif[0], ecfCoordinates, eciCoordinates,
3, 3, 1);
if (ecfPositionIfCoordinatesAreVelocity != NULL) {
double Tdotfi[3][3];
double Tdotif[3][3];
double Trot[3][3] = { { 0, Earth::OMEGA, 0 },
{ 0 - Earth::OMEGA, 0, 0 }, { 0, 0, 0 } };
double Ttemp2[3][3];
MatrixOperations<double>::multiply(mNutation[0], mPrecession[0],
Ttemp[0], 3, 3, 3);
MatrixOperations<double>::multiply(mTheta[0], Ttemp[0], Ttemp2[0], 3, 3,
3);
MatrixOperations<double>::multiply(Trot[0], Ttemp2[0], Tdotfi[0], 3, 3,
3);
MatrixOperations<double>::transpose(Tdotfi[0], Tdotif[0], 3);
double velocityCorrection[3];
MatrixOperations<double>::multiply(Tdotif[0],
ecfPositionIfCoordinatesAreVelocity, velocityCorrection, 3, 3,
1);
VectorOperations<double>::add(velocityCorrection, eciCoordinates,
eciCoordinates, 3);
}
}
CoordinateTransformations::CoordinateTransformations(uint8_t offset) :
utcGpsOffset(offset) {
}
CoordinateTransformations::~CoordinateTransformations() {
}
void CoordinateTransformations::setUtcGpsOffset(uint8_t offset) {
}