org.orekit.attitudes
Class YawCompensation

java.lang.Object
  org.orekit.attitudes.AbstractAttitudeLaw
      org.orekit.attitudes.GroundPointing
          org.orekit.attitudes.GroundPointingWrapper
              org.orekit.attitudes.YawCompensation

All Implemented Interfaces:

Serializable, AttitudeLaw, AttitudeLawModifier, AttitudeProvider

public class YawCompensation
extends GroundPointingWrapper

This class handles yaw compensation attitude provider.

Yaw compensation is mainly used for Earth observation satellites. As a satellites moves along its track, the image of ground points move on the focal point of the optical sensor. This motion is a combination of the satellite motion, but also on the Earth rotation and on the current attitude (in particular if the pointing includes Roll or Pitch offset). In order to reduce geometrical distortion, the yaw angle is changed a little from the simple ground pointing attitude such that the apparent motion of ground points is along a prescribed axis (orthogonal to the optical sensors rows), taking into account all effects.

This attitude is implemented as a wrapper on top of an underlying ground pointing law that defines the roll and pitch angles.

Instances of this class are guaranteed to be immutable.

Author:

Véronique Pommier-Maurussane

See Also:

GroundPointing, Serialized Form

Constructor Summary

YawCompensation(GroundPointing groundPointingLaw)
Creates a new instance.

Method Summary

Attitude	getAttitude(PVCoordinatesProvider pvProv, AbsoluteDate date, Frame frame) Compute the attitude corresponding to an orbital state.
TimeStampedAngularCoordinates	getCompensation(PVCoordinatesProvider pvProv, AbsoluteDate date, Frame orbitFrame, Attitude base) Compute the TimeStampedAngularCoordinates at a given time.
double	getYawAngle(PVCoordinatesProvider pvProv, AbsoluteDate date, Frame frame) Compute the yaw compensation angle at date.

Methods inherited from class org.orekit.attitudes.GroundPointingWrapper

getBaseState, getTargetPoint, getTargetPV, getUnderlyingAttitudeLaw, setSpinDerivativesComputation

Methods inherited from class org.orekit.attitudes.GroundPointing

getBodyFrame, getBodyShape

Methods inherited from class org.orekit.attitudes.AbstractAttitudeLaw

getAttitude, getSpinDerivativesComputation

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.orekit.attitudes.AttitudeProvider

getAttitude

Constructor Detail

YawCompensation

public YawCompensation(GroundPointing groundPointingLaw)

Creates a new instance.

Parameters:

groundPointingLaw - ground pointing attitude provider without yaw compensation

Method Detail

getAttitude

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

Compute the attitude corresponding to an orbital state.

Specified by:

getAttitude in interface AttitudeProvider

Overrides:

getAttitude in class GroundPointing

Parameters:

pvProv - local position-velocity provider around current date

date - current date

frame - reference frame from which attitude is computed

Returns:

attitude attitude on the specified date and position-velocity state

Throws:

OrekitException - if attitude cannot be computed

getCompensation

public TimeStampedAngularCoordinates getCompensation(PVCoordinatesProvider pvProv,
                                                     AbsoluteDate date,
                                                     Frame orbitFrame,
                                                     Attitude base)
                                              throws OrekitException

Compute the TimeStampedAngularCoordinates at a given time.

Specified by:

getCompensation in class GroundPointingWrapper

Parameters:

pvProv - provider for PV coordinates

date - date at which rotation is requested

orbitFrame - reference frame from which attitude is computed

base - base satellite attitude in given frame.

Returns:

compensation rotation at date, i.e rotation between non compensated attitude state and compensated state.

Throws:

OrekitException - if some specific error occurs

getYawAngle

public double getYawAngle(PVCoordinatesProvider pvProv,
                          AbsoluteDate date,
                          Frame frame)
                   throws OrekitException

Compute the yaw compensation angle at date.

Parameters:

pvProv - provider for PV coordinates

date - date at which compensation is requested

frame - reference frame from which attitude is computed

Returns:

yaw compensation angle for orbit.

Throws:

OrekitException - if some specific error occurs