org.orekit.attitudes.kinematics
Class KinematicsToolkit

java.lang.Object
  org.orekit.attitudes.kinematics.KinematicsToolkit

public final class KinematicsToolkit
extends Object

This class contains static methods performing kinematics operations.

Since:

1.2

Version:

$Id: KinematicsToolkit.java 13175 2015-05-06 13:44:38Z trapier $

Author:

Tiziana Sabatini, Rami Houdroge

Concurrency :

immutable

Nested Class Summary

static class

KinematicsToolkit.IntegrationType Integration types.

Field Summary

static double	DEFAULT_4HZ Default 4 Hz integration step.
static double	DEFAULT_8HZ Default 8 Hz integration step.

Method Summary

static Vector3D	computeSpin(double[] ang, double[] angd, RotationOrder order) Compute spin knowing the instantaneous quaternion and its derivative.
static Vector3D	computeSpin(Quaternion q, Quaternion qd) Compute spin knowing the instantaneous quaternion and its derivative.
static Quaternion	differentiateQuaternion(Quaternion q, Vector3D spin) Compute the derivative of a quaternion knowing the instantaneous spin.
static Vector3D	estimateSpin(Rotation start, Rotation end, double dt) Estimate spin between two orientations. Estimation is based on a simple fixed rate rotation during the time interval between the two attitude.
static Rotation	integrate(KinematicsToolkit.IntegrationType type, Rotation initOrientation, AbsoluteDate initDate, AbsoluteDate finalDate, Vector3DFunction spin, double step) Integrate a spin function.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_4HZ

public static final double DEFAULT_4HZ

Default 4 Hz integration step.

See Also:

Constant Field Values

DEFAULT_8HZ

public static final double DEFAULT_8HZ

Default 8 Hz integration step.

See Also:

Constant Field Values

Method Detail

estimateSpin

public static Vector3D estimateSpin(Rotation start,
                                    Rotation end,
                                    double dt)

Estimate spin between two orientations.
Estimation is based on a simple fixed rate rotation during the time interval between the two attitude. This method has been copied from the Attitude class; when the class KinematicsToolkit will be merged to Orekit, the Attitude estimateSpin method should be deleted.

Parameters:

start - start orientation

end - end orientation

dt - time elapsed between the dates of the two orientations

Returns:

the spin allowing to go from start to end orientation

computeSpin

public static Vector3D computeSpin(Quaternion q,
                                   Quaternion qd)

Compute spin knowing the instantaneous quaternion and its derivative.

Parameters:

q - the quaternion (rotation transforming frame R to frame S) at a given date

qd - the derivative of the quaternion at a given date

Returns:

the spin of the frame S with regard to frame R (expressed in frame S) at the given date

computeSpin

public static Vector3D computeSpin(double[] ang,
                                   double[] angd,
                                   RotationOrder order)
                            throws OrekitException

Compute spin knowing the instantaneous quaternion and its derivative.

Parameters:

ang - the angles describing a rotation from frame R to frame S at a given date

angd - the derivative of the angles

order - the rotation order: ZXZ for Euler angles, ZYX for Cardan angles

Returns:

the spin of the frame S with regard to frame R (expressed in frame S) at the given date

Throws:

OrekitException - the rotation order is not supported

differentiateQuaternion

public static Quaternion differentiateQuaternion(Quaternion q,
                                                 Vector3D spin)

Compute the derivative of a quaternion knowing the instantaneous spin.

Parameters:

q - the quaternion (rotation transforming frame R to frame S) at a given date

spin - the spin (from frame S to frame R, expressed in frame S) at the given date

Returns:

the derivative of the quaternion q at the given date.

integrate

public static Rotation integrate(KinematicsToolkit.IntegrationType type,
                                 Rotation initOrientation,
                                 AbsoluteDate initDate,
                                 AbsoluteDate finalDate,
                                 Vector3DFunction spin,
                                 double step)

Integrate a spin function. Use the Edwards method for integration of mobile rotation axes.

Parameters:

type - type of the integration (either Wilcox or Edwards)

initOrientation - rotation at initial date

initDate - initial date

finalDate - final date

spin - spin function

step - time step

Returns:

the computed rotation at final date