org.orekit.propagation

Class StateCovarianceBlender

java.lang.Object

org.orekit.time.AbstractTimeInterpolator<TimeStampedPair<Orbit,StateCovariance>>

org.orekit.propagation.AbstractStateCovarianceInterpolator

org.orekit.propagation.StateCovarianceBlender

All Implemented Interfaces:

TimeInterpolator<TimeStampedPair<Orbit,StateCovariance>>

public class StateCovarianceBlender
extends AbstractStateCovarianceInterpolator

State covariance blender.

Its purpose is to interpolate state covariance between tabulated state covariances by using the concept of blending, exposed in : "Efficient Covariance Interpolation using Blending of Approximate State Error Transitions" by Sergei Tanygin.

It propagates tabulated values to the interpolation date assuming a standard keplerian model and then blend each propagated covariances using a smoothstep function.

It gives accurate results as explained here. In the very poorly tracked test case evolving in a highly dynamical environment mentioned in the linked thread, the user can expect at worst errors of less than 0.25% in position sigmas and less than 0.4% in velocity sigmas with steps of 40mn between tabulated values.

Author:

Vincent Cucchietti

See Also:

SmoothStepFactory, SmoothStepFactory.SmoothStepFunction

Nested Class Summary

Nested classes/interfaces inherited from class org.orekit.time.AbstractTimeInterpolator

AbstractTimeInterpolator.InterpolationData

Field Summary

Fields inherited from class org.orekit.propagation.AbstractStateCovarianceInterpolator

COLUMN_DIM, DEFAULT_POSITION_ANGLE, ROW_DIM

Fields inherited from class org.orekit.time.AbstractTimeInterpolator

DEFAULT_EXTRAPOLATION_THRESHOLD_SEC, DEFAULT_INTERPOLATION_POINTS

Constructor Summary

Constructors

Constructor and Description
StateCovarianceBlender(org.hipparchus.analysis.polynomials.SmoothStepFactory.SmoothStepFunction blendingFunction, TimeInterpolator<Orbit> orbitInterpolator, Frame outFrame, OrbitType outOrbitType, PositionAngleType outPositionAngleType) Constructor.
StateCovarianceBlender(org.hipparchus.analysis.polynomials.SmoothStepFactory.SmoothStepFunction blendingFunction, TimeInterpolator<Orbit> orbitInterpolator, LOFType outLOF) Constructor.

Method Summary

Modifier and Type	Method and Description
protected StateCovariance	computeInterpolatedCovarianceInOrbitFrame(List<TimeStampedPair<Orbit,StateCovariance>> uncertainStates, Orbit interpolatedOrbit) Compute the interpolated covariance expressed in the interpolated orbit frame.

Methods inherited from class org.orekit.propagation.AbstractStateCovarianceInterpolator

expressCovarianceInDesiredOutput, getOrbitInterpolator, getOutFrame, getOutLOF, getOutOrbitType, getOutPositionAngleType, interpolate, interpolateOrbit

Methods inherited from class org.orekit.time.AbstractTimeInterpolator

addOptionalSubInterpolatorIfDefined, checkInterpolatorCompatibilityWithSampleSize, getCentralDate, getExtrapolationThreshold, getNbInterpolationPoints, getSubInterpolators, getTimeParameter, interpolate, interpolate

Methods inherited from class java.lang.Object

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

Constructor Detail

StateCovarianceBlender

public StateCovarianceBlender(org.hipparchus.analysis.polynomials.SmoothStepFactory.SmoothStepFunction blendingFunction,
                              TimeInterpolator<Orbit> orbitInterpolator,
                              LOFType outLOF)

Constructor.

BEWARE: If the output local orbital frame is not considered pseudo-inertial, all the covariance components related to the velocity will be poorly interpolated. Only the position covariance should be considered in this case.

Parameters:

blendingFunction - blending function

orbitInterpolator - orbit interpolator

outLOF - local orbital frame

See Also:

Frame, OrbitType, PositionAngleType

StateCovarianceBlender

public StateCovarianceBlender(org.hipparchus.analysis.polynomials.SmoothStepFactory.SmoothStepFunction blendingFunction,
                              TimeInterpolator<Orbit> orbitInterpolator,
                              Frame outFrame,
                              OrbitType outOrbitType,
                              PositionAngleType outPositionAngleType)

Constructor.

Parameters:

blendingFunction - blending function

orbitInterpolator - orbit interpolator

outFrame - desired output covariance frame

outPositionAngleType - desired output position angle

outOrbitType - desired output orbit type

See Also:

Frame, OrbitType, PositionAngleType

Method Detail

computeInterpolatedCovarianceInOrbitFrame

protected StateCovariance computeInterpolatedCovarianceInOrbitFrame(List<TimeStampedPair<Orbit,StateCovariance>> uncertainStates,
                                                                    Orbit interpolatedOrbit)

Compute the interpolated covariance expressed in the interpolated orbit frame.

Specified by:

computeInterpolatedCovarianceInOrbitFrame in class AbstractStateCovarianceInterpolator

Parameters:

uncertainStates - list of orbits and associated covariances

interpolatedOrbit - interpolated orbit

Returns:

interpolated covariance expressed in the interpolated orbit frame