Package gaiasky.util.gaia

Class MslAttitudeDataServer

java.lang.Object
gaiasky.util.gaia.BaseAttitudeDataServer<A>
gaiasky.util.gaia.NumericalAttitudeDataServer<Attitude>
gaiasky.util.gaia.HermiteInterpolatedAttitudeDataServer
gaiasky.util.gaia.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 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 long[] precessionRateChanges
      The times when the precession rate changes, calculated from reducedPrecession.

    • qExtraOmega

      protected Quaterniond 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)

    • 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

    • getAttitudeNative

      public Attitude 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
      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.