Package gaiasky.util.gaia

Class ConcreteAttitude

java.lang.Object

gaiasky.util.gaia.ConcreteAttitude

All Implemented Interfaces:

Attitude

public class ConcreteAttitude
extends java.lang.Object
implements Attitude

This class implements the Attitude interface and contains just the minimum fields necessary to define a unique attitude at a given time, plus a large number of methods to compute quantities that depend only on this attitude and time.

The various scanning laws and specific attitude representations (e.g., using splines, or tables for interpolation) can be implemented as providing attitude objects of this type.

In some cases (in particular for simple analytical scanning laws) there are more direct ways to retrieve some of the quantities for which there are methods in this class (e.g., getHeliotropicAnglesRates()); the present method(s) may then be overridden for efficiency.

Constructor Summary

Constructors

Constructor	Description
ConcreteAttitude(long t, Quaterniond q, boolean withZeroSigmaCorr)	Construct object from time, and a quaternion.
ConcreteAttitude(long t, Quaterniond q, Quaterniond qDot, boolean withZeroSigmaCorr)	Construct object from time, quaternion and its derivative.

Method Summary

Modifier and Type	Method	Description
double[]	getAlAcRates(double alInstrumentAngle, double acFieldAngle)	Compute the angular speed AL and AC of an inertial direction in the SRS frame, using instrument angles (phi, zeta).
double[]	getAlAcRates(FOV fov, double alFieldAngle, double acFieldAngle)	Compute the angular speed AL and AC of an inertial direction in the SRS frame, using field angles (fov, eta, zeta).
Vector3d[]	getFovDirections()	Get the PFoV and FFoV directions as an array of unit vectors expressed in the ICRS (or CoMRS).
HeliotropicAnglesRates	getHeliotropicAnglesRates()
Quaterniond	getQuaternion()
Quaterniond	getQuaternionDot()	Get the time derivative of the attitude.
Vector3d	getSpinVectorInIcrs()	Get the inertial spin vector in the ICRS (or CoMRS).
Vector3d	getSpinVectorInSrs()	Get the inertial spin vector in the SRS.
Vector3d[]	getSrsAxes(Vector3d[] xyz)	Get the x, y, z axes of the SRS as an array of three unit vectors expressed in the ICRS (or CoMRS).
long	getTime()	Get the time that this attitude is valid for as a single long value.
void	setQuaternion(Quaterniond q)	The the quaternion of the attitude.
void	setQuaternionDot(Quaterniond qDot)
void	setTime(long time)	Set the time of the attitude.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConcreteAttitude

public ConcreteAttitude(long t,
                        Quaterniond q,
                        boolean withZeroSigmaCorr)

Construct object from time, and a quaternion. This leaves the time derivative undefined. It can be set later with setQuaternionDot(Quaterniond)

Parameters:

t - time of the attitude

q - quaternion

ConcreteAttitude

public ConcreteAttitude(long t,
                        Quaterniond q,
                        Quaterniond qDot,
                        boolean withZeroSigmaCorr)

Construct object from time, quaternion and its derivative.

Parameters:

t - time of the attitude

q - quaternion

qDot - time derivative of quaternion [1/day]

Method Detail

getTime

public long getTime()

Description copied from interface: Attitude

Get the time that this attitude is valid for as a single long value. The meaning of the time depends on the TimeContext of the AttitudeDataServer that generated the attitude. Use #getGaiaTime() to get the time as an absolute GaiaTime if needed.

Specified by:

getTime in interface Attitude

Returns:

time time that the attitude is valid for

setTime

public void setTime(long time)

Set the time of the attitude. This usually does not make sense as the time is set during construction of the object

Parameters:

time - time of the attitude in [ns] since reference epoch

getQuaternion

public Quaterniond getQuaternion()

Specified by:

getQuaternion in interface Attitude

Returns:

quaternion that represents the attitude

setQuaternion

public void setQuaternion(Quaterniond q)

The the quaternion of the attitude. * Set the time of the attitude. This usually does not make sense as the time is set during construction of the

Parameters:

q -

getQuaternionDot

public Quaterniond getQuaternionDot()

Get the time derivative of the attitude.

Specified by:

getQuaternionDot in interface Attitude

Returns:

time derivative of the attitude quaternion [1/day]

setQuaternionDot

public void setQuaternionDot(Quaterniond qDot)

Parameters:

qDot - quaternion derivative to set - all components in [1/day]

getHeliotropicAnglesRates

public HeliotropicAnglesRates getHeliotropicAnglesRates()

getSpinVectorInSrs

public Vector3d getSpinVectorInSrs()

Description copied from interface: Attitude

Get the inertial spin vector in the SRS.

Specified by:

getSpinVectorInSrs in interface Attitude

Returns:

spin vector in [rad/day] relative to SRS

getSpinVectorInIcrs

public Vector3d getSpinVectorInIcrs()

Description copied from interface: Attitude

Get the inertial spin vector in the ICRS (or CoMRS).

Specified by:

getSpinVectorInIcrs in interface Attitude

Returns:

spin vector in [rad/day] relative to ICRS

getFovDirections

public Vector3d[] getFovDirections()

Description copied from interface: Attitude

Get the PFoV and FFoV directions as an array of unit vectors expressed in the ICRS (or CoMRS).

Specified by:

getFovDirections in interface Attitude

Returns:

array of two (PFoV, FFoV3) vectors

getSrsAxes

public Vector3d[] getSrsAxes(Vector3d[] xyz)

Description copied from interface: Attitude

Get the x, y, z axes of the SRS as an array of three unit vectors expressed in the ICRS (or CoMRS).

Specified by:

getSrsAxes in interface Attitude

Returns:

array of three (x, y, z) vectors

See Also:

Attitude.getSrsAxes(Vector3d[])

getAlAcRates

public double[] getAlAcRates(double alInstrumentAngle,
                             double acFieldAngle)

Description copied from interface: Attitude

Compute the angular speed AL and AC of an inertial direction in the SRS frame, using instrument angles (phi, zeta).

Specified by:

getAlAcRates in interface Attitude

Parameters:

alInstrumentAngle - (=AL angle phi) of the direction [rad]

acFieldAngle - (=AC angle zeta) of the direction [rad]

Returns:

two-element double array containing the angular speed AL and AC [rad/s]

getAlAcRates

public double[] getAlAcRates(FOV fov,
                             double alFieldAngle,
                             double acFieldAngle)

Description copied from interface: Attitude

Compute the angular speed AL and AC of an inertial direction in the SRS frame, using field angles (fov, eta, zeta).

Specified by:

getAlAcRates in interface Attitude

Parameters:

fov - FOV (Preceding or Following)

alFieldAngle - (=AL angle eta) of the direction [rad]

acFieldAngle - (=AC angle zeta) of the direction [rad]

Returns:

two-element double array containing the angular speed AL and AC [rad/s]