Package org.orekit.estimation.measurements

Class EstimatedEarthFrameProvider

java.lang.Object

org.orekit.estimation.measurements.EstimatedEarthFrameProvider

All Implemented Interfaces:

Serializable, TransformProvider

public class EstimatedEarthFrameProvider
extends Object
implements TransformProvider

Class modeling an Earth frame whose Earth Orientation Parameters can be estimated.

This class adds parameters for an additional polar motion and an additional prime meridian orientation on top of an underlying regular Earth frame like ITRF. The polar motion and prime meridian orientation are applied after regular Earth orientation parameters, so the value of the estimated parameters will be correction to EOP, they will not be the complete EOP values by themselves. Basically, this means that for Earth, the following transforms are applied in order, between inertial frame and this frame:

1. precession/nutation, as theoretical model plus celestial pole EOP parameters
2. body rotation, as theoretical model plus prime meridian EOP parameters
3. polar motion, which is only from EOP parameters (no theoretical models)
4. additional body rotation, controlled by getPrimeMeridianOffsetDriver() and getPrimeMeridianDriftDriver()
5. additional polar motion, controlled by getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetYDriver() and getPolarDriftYDriver()

Since:

9.1

Author:

Luc Maisonobe

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
static double	EARTH_ANGULAR_VELOCITY	Earth Angular Velocity, in rad/s, from TIRF model.

Constructor Summary

Constructors

Constructor	Description
EstimatedEarthFrameProvider(UT1Scale baseUT1)	Build an estimated Earth frame.

Method Summary

Modifier and Type	Method	Description
UT1Scale	getEstimatedUT1()	Get the estimated UT1 time scale.
ParameterDriver	getPolarDriftXDriver()	Get a driver allowing to add a polar drift along X.
ParameterDriver	getPolarDriftYDriver()	Get a driver allowing to add a polar drift along Y.
ParameterDriver	getPolarOffsetXDriver()	Get a driver allowing to add a polar offset along X.
ParameterDriver	getPolarOffsetYDriver()	Get a driver allowing to add a polar offset along Y.
ParameterDriver	getPrimeMeridianDriftDriver()	Get a driver allowing to add a prime meridian rotation rate.
ParameterDriver	getPrimeMeridianOffsetDriver()	Get a driver allowing to add a prime meridian rotation.
Transform	getTransform(AbsoluteDate date)	Get the Transform corresponding to specified date.
FieldTransform<DerivativeStructure>	getTransform(FieldAbsoluteDate<DerivativeStructure> date, DSFactory factory, Map<String,Integer> indices)	Get the transform with derivatives.
<T extends RealFieldElement<T>> FieldTransform<T>	getTransform(FieldAbsoluteDate<T> date)	Get the FieldTransform corresponding to specified date.

Methods inherited from class java.lang.Object

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

Field Detail

EARTH_ANGULAR_VELOCITY

public static final double EARTH_ANGULAR_VELOCITY

Earth Angular Velocity, in rad/s, from TIRF model.

See Also:

Constant Field Values

Constructor Detail

EstimatedEarthFrameProvider

public EstimatedEarthFrameProvider(UT1Scale baseUT1)
                            throws OrekitException

Build an estimated Earth frame.

The initial values for the pole and prime meridian parametric linear models (getPrimeMeridianOffsetDriver(), getPrimeMeridianDriftDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver(), getPolarOffsetXDriver(), getPolarDriftXDriver()) are set to 0.

Parameters:

baseUT1 - underlying base UT1

Throws:

OrekitException - if scales are too close to zero (never happens)

Since:

9.1

Method Detail

getPrimeMeridianOffsetDriver

public ParameterDriver getPrimeMeridianOffsetDriver()

Get a driver allowing to add a prime meridian rotation.

The parameter is an angle in radians. In order to convert this value to a DUT1 in seconds, the value must be divided by EARTH_ANGULAR_VELOCITY (nominal Angular Velocity of Earth).

Returns:

driver for prime meridian rotation

getPrimeMeridianDriftDriver

public ParameterDriver getPrimeMeridianDriftDriver()

Get a driver allowing to add a prime meridian rotation rate.

The parameter is an angle rate in radians per second. In order to convert this value to a LOD in seconds, the value must be multiplied by -86400 and divided by EARTH_ANGULAR_VELOCITY (nominal Angular Velocity of Earth).

Returns:

driver for prime meridian rotation rate

getPolarOffsetXDriver

public ParameterDriver getPolarOffsetXDriver()

Get a driver allowing to add a polar offset along X.

The parameter is an angle in radians

Returns:

driver for polar offset along X

getPolarDriftXDriver

public ParameterDriver getPolarDriftXDriver()

Get a driver allowing to add a polar drift along X.

The parameter is an angle rate in radians per second

Returns:

driver for polar drift along X

getPolarOffsetYDriver

public ParameterDriver getPolarOffsetYDriver()

Get a driver allowing to add a polar offset along Y.

The parameter is an angle in radians

Returns:

driver for polar offset along Y

getPolarDriftYDriver

public ParameterDriver getPolarDriftYDriver()

Get a driver allowing to add a polar drift along Y.

The parameter is an angle rate in radians per second

Returns:

driver for polar drift along Y

getEstimatedUT1

public UT1Scale getEstimatedUT1()

Get the estimated UT1 time scale.

Returns:

estimated UT1 time scale

getTransform

public Transform getTransform(AbsoluteDate date)
                       throws OrekitException

Get the Transform corresponding to specified date.

Specified by:

getTransform in interface TransformProvider

Parameters:

date - current date

Returns:

transform at specified date

Throws:

OrekitException - if transform cannot be computed at given date

getTransform

public <T extends RealFieldElement<T>> FieldTransform<T> getTransform(FieldAbsoluteDate<T> date)
                                                               throws OrekitException

Get the FieldTransform corresponding to specified date.

Specified by:

getTransform in interface TransformProvider

Type Parameters:

T - type of the field elements

Parameters:

date - current date

Returns:

transform at specified date

Throws:

OrekitException - if transform cannot be computed at given date

getTransform

public FieldTransform<DerivativeStructure> getTransform(FieldAbsoluteDate<DerivativeStructure> date,
                                                        DSFactory factory,
                                                        Map<String,Integer> indices)
                                                 throws OrekitException

Get the transform with derivatives.

Parameters:

date - date of the transform

factory - factory for the derivatives

indices - indices of the estimated parameters in derivatives computations

Returns:

computed transform with derivatives

Throws:

OrekitException - if some frame transforms cannot be computed