fr.cnes.sirius.patrius.attitudes

Class IsisSunAndPseudoSpinPointing

java.lang.Object

fr.cnes.sirius.patrius.attitudes.AbstractAttitudeLaw

fr.cnes.sirius.patrius.attitudes.IsisSunAndPseudoSpinPointing

All Implemented Interfaces:

AttitudeLaw, AttitudeProvider, Serializable

public class IsisSunAndPseudoSpinPointing
extends AbstractAttitudeLaw

This class handles SunIsis and PseudoSpin attitude provider. This law is composed of a base frame (SUN ISIS) defined as
- Z_sun = direction Sun->Sat
- X_sun = Z_sun^orbitalMomentum with sign so that X_sun(3) is negative (FLAG 1 if negated else 0)
followed by a rotation about the Z_sun axis of angle:
bias = - BETA_SIGN * alpha – PHI + FLAG * PI + (1 – BETA_SIGN) * PI/2
where alpha is the Sat->Sun angle with Z in the LVLH XZ plane Note that due to simplifications in the computation (eg fixed sun, keplerian motion, fixed orbital plane) the angular velocity has an approximate error of O(E-7) rad/sec (real value is O(E-3) as driven by orbital period) and angular acceleration is not computed (zero), likely O(E-9) rad/s2

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
IsisSunAndPseudoSpinPointing(IDirection dirSun, double pseudoSpinPhase, boolean positiveBetaSign) Constructor.

Method Summary

Modifier and Type	Method and Description
Attitude	getAttitude(PVCoordinatesProvider pvProv, AbsoluteDate date, Frame frame) Compute the attitude corresponding to an orbital state.

Methods inherited from class fr.cnes.sirius.patrius.attitudes.AbstractAttitudeLaw

getSpinDerivativesComputation, setSpinDerivativesComputation

Methods inherited from class java.lang.Object

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

Methods inherited from interface fr.cnes.sirius.patrius.attitudes.AttitudeProvider

computeSpinByFD, computeSpinDerivativeByFD, getAttitude

Constructor Detail

IsisSunAndPseudoSpinPointing

public IsisSunAndPseudoSpinPointing(IDirection dirSun,
                                    double pseudoSpinPhase,
                                    boolean positiveBetaSign)

Constructor.

Parameters:

dirSun - sun direction to use

pseudoSpinPhase - phase adjustment

positiveBetaSign - desired beta sign (true positive, false negative)

Method Detail

getAttitude

public Attitude getAttitude(PVCoordinatesProvider pvProv,
                            AbsoluteDate date,
                            Frame frame)
                     throws PatriusException

Compute the attitude corresponding to an orbital state.

Parameters:

pvProv - local position-velocity provider around current date

date - current date

frame - reference frame from which attitude is computed

Returns:

attitude on the specified date and position-velocity state

Throws:

PatriusException - if attitude cannot be computed for provided date