org.orekit.orbits

Class FieldCartesianOrbit<T extends CalculusFieldElement<T>>

java.lang.Object

org.orekit.orbits.FieldOrbit<T>

org.orekit.orbits.FieldCartesianOrbit<T>

All Implemented Interfaces:

FieldTimeInterpolable<FieldOrbit<T>,T>, FieldTimeShiftable<FieldOrbit<T>,T>, FieldTimeStamped<T>, FieldPVCoordinatesProvider<T>

public class FieldCartesianOrbit<T extends CalculusFieldElement<T>>
extends FieldOrbit<T>

This class holds Cartesian orbital parameters.

The parameters used internally are the Cartesian coordinates:

• x
• y
• z
• xDot
• yDot
• zDot

contained in PVCoordinates.

Note that the implementation of this class delegates all non-Cartesian related computations (getA(), getEquinoctialEx(), ...) to an underlying instance of the EquinoctialOrbit class. This implies that using this class only for analytical computations which are always based on non-Cartesian parameters is perfectly possible but somewhat sub-optimal.

The instance CartesianOrbit is guaranteed to be immutable.

Since:

9.0

Author:

Luc Maisonobe, Guylaine Prat, Fabien Maussion, Véronique Pommier-Maurussane

See Also:

Orbit, KeplerianOrbit, CircularOrbit, EquinoctialOrbit

Constructor Summary

Constructors

Constructor and Description
FieldCartesianOrbit(FieldOrbit<T> op) Constructor from any kind of orbital parameters.
FieldCartesianOrbit(FieldPVCoordinates<T> pvaCoordinates, Frame frame, FieldAbsoluteDate<T> date, T mu) Constructor from Cartesian parameters.
FieldCartesianOrbit(TimeStampedFieldPVCoordinates<T> pvaCoordinates, Frame frame, T mu) Constructor from Cartesian parameters.

Method Summary

Modifier and Type	Method and Description
void	addKeplerContribution(PositionAngle type, T gm, T[] pDot) Add the contribution of the Keplerian motion to parameters derivatives
protected T[][]	computeJacobianEccentricWrtCartesian() Compute the Jacobian of the orbital parameters with eccentric angle with respect to the Cartesian parameters.
protected T[][]	computeJacobianMeanWrtCartesian() Compute the Jacobian of the orbital parameters with mean angle with respect to the Cartesian parameters.
protected T[][]	computeJacobianTrueWrtCartesian() Compute the Jacobian of the orbital parameters with true angle with respect to the Cartesian parameters.
T	getA() Get the semi-major axis.
T	getADot() Get the semi-major axis derivative.
T	getE() Get the eccentricity.
T	getEDot() Get the eccentricity derivative.
T	getEquinoctialEx() Get the first component of the equinoctial eccentricity vector.
T	getEquinoctialExDot() Get the first component of the equinoctial eccentricity vector.
T	getEquinoctialEy() Get the second component of the equinoctial eccentricity vector.
T	getEquinoctialEyDot() Get the second component of the equinoctial eccentricity vector.
T	getHx() Get the first component of the inclination vector.
T	getHxDot() Get the first component of the inclination vector derivative.
T	getHy() Get the second component of the inclination vector.
T	getHyDot() Get the second component of the inclination vector derivative.
T	getI() Get the inclination.
T	getIDot() Get the inclination derivative.
T	getLE() Get the eccentric longitude argument.
T	getLEDot() Get the eccentric longitude argument derivative.
T	getLM() Get the mean longitude argument.
T	getLMDot() Get the mean longitude argument derivative.
T	getLv() Get the true longitude argument.
T	getLvDot() Get the true longitude argument derivative.
OrbitType	getType() Get the orbit type.
boolean	hasDerivatives() Check if orbit includes derivatives.
protected TimeStampedFieldPVCoordinates<T>	initPVCoordinates() Compute the position/velocity coordinates from the canonical parameters.
FieldCartesianOrbit<T>	interpolate(FieldAbsoluteDate<T> date, Stream<FieldOrbit<T>> sample) Get an interpolated instance.
FieldCartesianOrbit<T>	shiftedBy(double dt) Get a time-shifted instance.
FieldCartesianOrbit<T>	shiftedBy(T dt) Get a time-shifted orbit.
CartesianOrbit	toOrbit() Transforms the FieldOrbit instance into an Orbit instance.
String	toString() Returns a string representation of this Orbit object.

Methods inherited from class org.orekit.orbits.FieldOrbit

fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, fillHalfRow, getDate, getFrame, getJacobianWrtCartesian, getJacobianWrtParameters, getKeplerianMeanMotion, getKeplerianPeriod, getMu, getPVCoordinates, getPVCoordinates, getPVCoordinates, hasNonKeplerianAcceleration

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.orekit.time.FieldTimeInterpolable

interpolate

Constructor Detail

FieldCartesianOrbit

public FieldCartesianOrbit(TimeStampedFieldPVCoordinates<T> pvaCoordinates,
                           Frame frame,
                           T mu)
                    throws IllegalArgumentException

Constructor from Cartesian parameters.

The acceleration provided in pvCoordinates is accessible using FieldOrbit.getPVCoordinates() and FieldOrbit.getPVCoordinates(Frame). All other methods use mu and the position to compute the acceleration, including shiftedBy(CalculusFieldElement) and FieldOrbit.getPVCoordinates(FieldAbsoluteDate, Frame).

Parameters:

pvaCoordinates - the position, velocity and acceleration of the satellite.

frame - the frame in which the PVCoordinates are defined (must be a pseudo-inertial frame)

mu - central attraction coefficient (m³/s²)

Throws:

IllegalArgumentException - if frame is not a pseudo-inertial frame

FieldCartesianOrbit

public FieldCartesianOrbit(FieldPVCoordinates<T> pvaCoordinates,
                           Frame frame,
                           FieldAbsoluteDate<T> date,
                           T mu)
                    throws IllegalArgumentException

Constructor from Cartesian parameters.

The acceleration provided in pvCoordinates is accessible using FieldOrbit.getPVCoordinates() and FieldOrbit.getPVCoordinates(Frame). All other methods use mu and the position to compute the acceleration, including shiftedBy(CalculusFieldElement) and FieldOrbit.getPVCoordinates(FieldAbsoluteDate, Frame).

Parameters:

pvaCoordinates - the position and velocity of the satellite.

frame - the frame in which the PVCoordinates are defined (must be a pseudo-inertial frame)

date - date of the orbital parameters

mu - central attraction coefficient (m³/s²)

Throws:

IllegalArgumentException - if frame is not a pseudo-inertial frame

FieldCartesianOrbit

public FieldCartesianOrbit(FieldOrbit<T> op)

Constructor from any kind of orbital parameters.

Parameters:

op - orbital parameters to copy

Method Detail

getType

public OrbitType getType()

Get the orbit type.

Specified by:

getType in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

orbit type

getA

public T getA()

Get the semi-major axis.

Note that the semi-major axis is considered negative for hyperbolic orbits.

Specified by:

getA in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

semi-major axis (m)

getADot

public T getADot()

Get the semi-major axis derivative.

Note that the semi-major axis is considered negative for hyperbolic orbits.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getADot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

semi-major axis derivative (m/s)

getE

public T getE()

Get the eccentricity.

Specified by:

getE in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

eccentricity

getEDot

public T getEDot()

Get the eccentricity derivative.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getEDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

eccentricity derivative

getI

public T getI()

Get the inclination.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getI in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

inclination (rad)

getIDot

public T getIDot()

Get the inclination derivative.

Specified by:

getIDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

inclination derivative (rad/s)

getEquinoctialEx

public T getEquinoctialEx()

Get the first component of the equinoctial eccentricity vector.

Specified by:

getEquinoctialEx in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

first component of the equinoctial eccentricity vector

getEquinoctialExDot

public T getEquinoctialExDot()

Get the first component of the equinoctial eccentricity vector.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getEquinoctialExDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

first component of the equinoctial eccentricity vector

getEquinoctialEy

public T getEquinoctialEy()

Get the second component of the equinoctial eccentricity vector.

Specified by:

getEquinoctialEy in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

second component of the equinoctial eccentricity vector

getEquinoctialEyDot

public T getEquinoctialEyDot()

Get the second component of the equinoctial eccentricity vector.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getEquinoctialEyDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

second component of the equinoctial eccentricity vector

getHx

public T getHx()

Get the first component of the inclination vector.

Specified by:

getHx in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

first component of the inclination vector

getHxDot

public T getHxDot()

Get the first component of the inclination vector derivative.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getHxDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

first component of the inclination vector derivative

getHy

public T getHy()

Get the second component of the inclination vector.

Specified by:

getHy in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

second component of the inclination vector

getHyDot

public T getHyDot()

Get the second component of the inclination vector derivative.

Specified by:

getHyDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

second component of the inclination vector derivative

getLv

public T getLv()

Get the true longitude argument.

Specified by:

getLv in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

v + ω + Ω true longitude argument (rad)

getLvDot

public T getLvDot()

Get the true longitude argument derivative.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getLvDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

d(v + ω + Ω)/dt true longitude argument derivative (rad/s)

getLE

public T getLE()

Get the eccentric longitude argument.

Specified by:

getLE in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

E + ω + Ω eccentric longitude argument (rad)

getLEDot

public T getLEDot()

Get the eccentric longitude argument derivative.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getLEDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

d(E + ω + Ω)/dt eccentric longitude argument derivative (rad/s)

getLM

public T getLM()

Get the mean longitude argument.

Specified by:

getLM in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

M + ω + Ω mean longitude argument (rad)

getLMDot

public T getLMDot()

Get the mean longitude argument derivative.

If the orbit was created without derivatives, the value returned is null.

Specified by:

getLMDot in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

d(M + ω + Ω)/dt mean longitude argument derivative (rad/s)

hasDerivatives

public boolean hasDerivatives()

Check if orbit includes derivatives.

Specified by:

hasDerivatives in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

true if orbit includes derivatives

See Also:

FieldOrbit.getADot(), FieldOrbit.getEquinoctialExDot(), FieldOrbit.getEquinoctialEyDot(), FieldOrbit.getHxDot(), FieldOrbit.getHyDot(), FieldOrbit.getLEDot(), FieldOrbit.getLvDot(), FieldOrbit.getLMDot(), FieldOrbit.getEDot(), FieldOrbit.getIDot()

initPVCoordinates

protected TimeStampedFieldPVCoordinates<T> initPVCoordinates()

Compute the position/velocity coordinates from the canonical parameters.

Specified by:

initPVCoordinates in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

computed position/velocity coordinates

shiftedBy

public FieldCartesianOrbit<T> shiftedBy(double dt)

Get a time-shifted instance.

Parameters:

dt - time shift in seconds

Returns:

a new instance, shifted with respect to instance (which is not changed)

shiftedBy

public FieldCartesianOrbit<T> shiftedBy(T dt)

Get a time-shifted orbit.

The orbit can be slightly shifted to close dates. This shift is based on a simple Keplerian model. It is not intended as a replacement for proper orbit and attitude propagation but should be sufficient for small time shifts or coarse accuracy.

Specified by:

shiftedBy in interface FieldTimeShiftable<FieldOrbit<T extends CalculusFieldElement<T>>,T extends CalculusFieldElement<T>>

Specified by:

shiftedBy in class FieldOrbit<T extends CalculusFieldElement<T>>

Parameters:

dt - time shift in seconds

Returns:

a new orbit, shifted with respect to the instance (which is immutable)

interpolate

public FieldCartesianOrbit<T> interpolate(FieldAbsoluteDate<T> date,
                                          Stream<FieldOrbit<T>> sample)

Get an interpolated instance.

Note that the state of the current instance may not be used in the interpolation process, only its type and non interpolable fields are used (for example central attraction coefficient or frame when interpolating orbits). The interpolable fields taken into account are taken only from the states of the sample points. So if the state of the instance must be used, the instance should be included in the sample points.

Note that this method is designed for small samples only (say up to about 10-20 points) so it can be implemented using polynomial interpolation (typically Hermite interpolation). Using too much points may induce Runge's phenomenon and numerical problems (including NaN appearing).

The interpolated instance is created by polynomial Hermite interpolation ensuring velocity remains the exact derivative of position.

As this implementation of interpolation is polynomial, it should be used only with small samples (about 10-20 points) in order to avoid Runge's phenomenon and numerical problems (including NaN appearing).

If orbit interpolation on large samples is needed, using the Ephemeris class is a better way than using this low-level interpolation. The Ephemeris class automatically handles selection of a neighboring sub-sample with a predefined number of point from a large global sample in a thread-safe way.

Parameters:

date - interpolation date

sample - sample points on which interpolation should be done

Returns:

a new instance, interpolated at specified date

computeJacobianMeanWrtCartesian

protected T[][] computeJacobianMeanWrtCartesian()

Description copied from class: FieldOrbit

Compute the Jacobian of the orbital parameters with mean angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianMeanWrtCartesian in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

6x6 Jacobian matrix

See Also:

FieldOrbit.computeJacobianEccentricWrtCartesian(), FieldOrbit.computeJacobianTrueWrtCartesian()

computeJacobianEccentricWrtCartesian

protected T[][] computeJacobianEccentricWrtCartesian()

Description copied from class: FieldOrbit

Compute the Jacobian of the orbital parameters with eccentric angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianEccentricWrtCartesian in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

6x6 Jacobian matrix

See Also:

FieldOrbit.computeJacobianMeanWrtCartesian(), FieldOrbit.computeJacobianTrueWrtCartesian()

computeJacobianTrueWrtCartesian

protected T[][] computeJacobianTrueWrtCartesian()

Description copied from class: FieldOrbit

Compute the Jacobian of the orbital parameters with true angle with respect to the Cartesian parameters.

Element jacobian[i][j] is the derivative of parameter i of the orbit with respect to Cartesian coordinate j. This means each row correspond to one orbital parameter whereas columns 0 to 5 correspond to the Cartesian coordinates x, y, z, xDot, yDot and zDot.

Specified by:

computeJacobianTrueWrtCartesian in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

6x6 Jacobian matrix

See Also:

FieldOrbit.computeJacobianMeanWrtCartesian(), FieldOrbit.computeJacobianEccentricWrtCartesian()

addKeplerContribution

public void addKeplerContribution(PositionAngle type,
                                  T gm,
                                  T[] pDot)

Add the contribution of the Keplerian motion to parameters derivatives

This method is used by integration-based propagators to evaluate the part of Keplerian motion to evolution of the orbital state.

Specified by:

addKeplerContribution in class FieldOrbit<T extends CalculusFieldElement<T>>

Parameters:

type - type of the position angle in the state

gm - attraction coefficient to use

pDot - array containing orbital state derivatives to update (the Keplerian part must be added to the array components, as the array may already contain some non-zero elements corresponding to non-Keplerian parts)

toString

public String toString()

Returns a string representation of this Orbit object.

Overrides:

toString in class Object

Returns:

a string representation of this object

toOrbit

public CartesianOrbit toOrbit()

Description copied from class: FieldOrbit

Transforms the FieldOrbit instance into an Orbit instance.

Specified by:

toOrbit in class FieldOrbit<T extends CalculusFieldElement<T>>

Returns:

Orbit instance with same properties