Package gaiasky.util.gaia

Class MslAttitudeDataServer

  • public class MslAttitudeDataServer
extends HermiteInterpolatedAttitudeDataServer
    This class implements the Modified Scanning Law (MSL) by Hermite interpolation of the attitude quaternion among values obtained by numerical integration of the basic equations in heliotropic angles.

    • Field Detail

      • 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 long[] precessionRateChanges
        The times when the precession rate changes, calculated from reducedPrecession.

      • qExtraOmega

        protected Quaterniond qExtraOmega
        Quaterniond corresponding to extraOmega

    • Constructor Detail

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

    • Method Detail

      • inGap

        public boolean inGap​(long time)

      • 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]

      • 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]

      • 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 }

      • 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]

      • 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]

      • 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

      • isModified

        public boolean isModified​(long t)
        Returns true if the precession rate is reduced in the interpolation interval containing t
        Parameters:
        t -
        Returns:

      • 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.