Package gaiasky.util.gaia

Class MslAttitudeDataServer

java.lang.Object

gaiasky.util.gaia.BaseAttitudeDataServer<IAttitude>

gaiasky.util.gaia.NumericalAttitudeDataServer<IAttitude>

gaiasky.util.gaia.HermiteInterpolatedAttitudeDataServer

gaiasky.util.gaia.MslAttitudeDataServer

public class MslAttitudeDataServer
extends HermiteInterpolatedAttitudeDataServer

Field Summary

Fields

Modifier and Type	Field	Description
protected double	extraOmega	An extra rotation by this angle [rad] is added to the generated attitude
protected double	maxStepSec	Maximum step size for the Hermite interpolation.
protected ModifiedScanningLaw	msl
protected long[]	precessionRateChanges	The times when the precession rate changes, calculated from reducedPrecession.
protected QuaternionDouble	qExtraOmega	Quaterniond corresponding to extraOmega
protected boolean[]	reducedPrecession	Keep track of times when the precession rate is reduced
protected long	step	Actual time step for Hermite interpolation, in [ns]
protected long	stepForIntegrator
protected long	timeGranularity	The actual starting and end times of the time period covered by the Hermite nodes must be multiples of the timeGranularity since the scanning law reference epoch.
protected boolean[]	transitionPrecession	Keep track of times when the precession rate is in a transition from nominal to reduced, or vice versa
protected boolean	useDefaultStepForIntegrator	The default integrator time step is the same as for Hermite interpolation.

Fields inherited from class gaiasky.util.gaia.HermiteInterpolatedAttitudeDataServer

nT, qW, qX, qY, qZ, rateX, rateY, rateZ, tNs

Fields inherited from class gaiasky.util.gaia.NumericalAttitudeDataServer

gtis

Fields inherited from class gaiasky.util.gaia.BaseAttitudeDataServer

initialized, initialRequestedTimeContext, nativeTimeContext, withUncertaintiesCorrelations

Constructor Summary

Constructors

Constructor	Description
MslAttitudeDataServer(long tStart, Duration tLength, ModifiedScanningLaw msl)	Constructor for given start time and mission length

Method Summary

Modifier and Type	Method	Description
IAttitude	getAttitudeNative(long t)	Evaluate the attitude in the native time system of the server
double	getMaxStep()	Return the currently set maximum step used in the Hermite interpolation
ModifiedScanningLaw	getMsl()	Returns the underlying ModeifiedScanningLaw.
long[]	getNodeParams()	Return the parameters defining the Hermite interpolation nodes (array tNs)
long[]	getPrecessionRateChanges()	Get a list of the (approximate) times when the precession rate has changed.
double	getRefOmega()	Returns the (effective) reference value of the heliotropic angle Omega.
boolean	inGap(long time)
void	initialize()	Any numerical attitude needs to be initialized
boolean	isModified(long t)	Returns true if the precession rate is reduced in the interpolation interval containing t
boolean	isTransition(long t)	Returns true if the precession rate is in a transition phase during the interval containing t
void	setMaxStep(double maxStepInSec)	Set the maximum step size to be used in the Hermite interpolation.
void	setMaxStepForIntegrator(double maxStepInSec)	This allows to override the default choice of max step for integrator
void	setRefOmega(double refOmega)	Sets the (effective) reference value of the heliotropic angle Omega.

Methods inherited from class gaiasky.util.gaia.NumericalAttitudeDataServer

getGtis, getStartTime, getStopTime, isValid

Methods inherited from class gaiasky.util.gaia.BaseAttitudeDataServer

getAttitude, getAttitude, getAttitude, getRefTime, isInitialized, setInitialized, setRefTime

Methods inherited from class java.lang.Object

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

Field Details

msl

protected ModifiedScanningLaw msl

maxStepSec

protected double maxStepSec

Maximum step size for the Hermite interpolation.

step

protected long step

Actual time step for Hermite interpolation, in [ns]

timeGranularity

protected long timeGranularity

The actual starting and end times of the time period covered by the Hermite nodes must be multiples of the timeGranularity since the scanning law reference epoch. This implies that the actual Hermite time step must be an integer fraction of the granularity.

useDefaultStepForIntegrator

protected boolean useDefaultStepForIntegrator

The default integrator time step is the same as for Hermite interpolation. This can be overridden by setMaxStepForINtegrator(double).

stepForIntegrator

protected long stepForIntegrator

extraOmega

protected double extraOmega

An extra rotation by this angle [rad] is added to the generated attitude

reducedPrecession

protected boolean[] reducedPrecession

Keep track of times when the precession rate is reduced

transitionPrecession

protected boolean[] transitionPrecession

Keep track of times when the precession rate is in a transition from nominal to reduced, or vice versa

precessionRateChanges

protected volatile long[] precessionRateChanges

The times when the precession rate changes, calculated from reducedPrecession.

qExtraOmega

protected QuaternionDouble qExtraOmega

Quaterniond corresponding to extraOmega

Constructor Details

MslAttitudeDataServer

public MslAttitudeDataServer(long tStart,
 Duration tLength,
 ModifiedScanningLaw msl)

Constructor for given start time and mission length

Parameters:

tStart - start time

tLength - coverage length

msl - the underlying scanning law

Throws:

IllegalArgumentException - if the tStart is before the start time of the passed scanning law, msl.

Method Details

initialize

public void initialize()

Description copied from class: NumericalAttitudeDataServer

Any numerical attitude needs to be initialized

Specified by:

initialize in class HermiteInterpolatedAttitudeDataServer

See Also:

• HermiteInterpolatedAttitudeDataServer.initialize()

inGap

public boolean inGap(long time)

setMaxStepForIntegrator

public void setMaxStepForIntegrator(double maxStepInSec)

This allows to override the default choice of max step for integrator

Parameters:

maxStepInSec - maximum step in [s]

getMaxStep

public double getMaxStep()

Return the currently set maximum step used in the Hermite interpolation

Returns:

step [sec]

setMaxStep

public void setMaxStep(double maxStepInSec)

Set the maximum step size to be used in the Hermite interpolation. Replaces the default value set at construction.

Parameters:

maxStepInSec - [sec]

getNodeParams

public long[] getNodeParams()

Return the parameters defining the Hermite interpolation nodes (array tNs)

Note: Although the super (HermiteInterpolatedAttitudeDataServer) permits to use a non-equidistant grid of Hermite nodes, the grid in MslAttitudeDataServer is always equidistant. It is therefore completely specified by three parameters: (1) the first point (= tNs[0]), (2) the increment (= tNs[1] - tNs[0]), and (3) the number of nodes (nT). These three values are returned as a long[] array.

Returns:

{ first node, increment, number of nodes }

getRefOmega

public double getRefOmega()

Returns the (effective) reference value of the heliotropic angle Omega.

This is the sum of refOmega (as set in the MSL) and extraOmega

Returns:

effective reference value of Omega in [rad]

setRefOmega

public void setRefOmega(double refOmega)

Sets the (effective) reference value of the heliotropic angle Omega.

To avoid re-initializing, extraOmega is set to the difference between the requested refOmega and the value set in the MSL

Parameters:

refOmega - reference value of Omega in [rad]

getMsl

public ModifiedScanningLaw getMsl()

Returns the underlying ModeifiedScanningLaw. This can be used to retrieve refNu, precRate, scanRate, etc.

Returns:

ModifiedScanningLaw used to set up the attitude data server

getAttitudeNative

public IAttitude getAttitudeNative(long t)
                            throws RuntimeException

Description copied from class: BaseAttitudeDataServer

Evaluate the attitude in the native time system of the server

Overrides:

getAttitudeNative in class HermiteInterpolatedAttitudeDataServer

Parameters:

t - - the time elapsed since the epoch of J2010 in ns (TCB)

Returns:

attitude for the given time

Throws:

RuntimeException

See Also:

• BaseAttitudeDataServer.getAttitude(long)

isModified

public boolean isModified(long t)

Returns true if the precession rate is reduced in the interpolation interval containing t

isTransition

public boolean isTransition(long t)

Returns true if the precession rate is in a transition phase during the interval containing t

Parameters:

t - The rate

Returns:

Whether it is in a transition phase

getPrecessionRateChanges

public long[] getPrecessionRateChanges()

Get a list of the (approximate) times when the precession rate has changed.