/* Copyright 2002-2017 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.frames;
import org.hipparchus.geometry.euclidean.threed.Rotation;
import org.hipparchus.geometry.euclidean.threed.Vector3D;
import org.orekit.time.AbsoluteDate;
import org.orekit.utils.PVCoordinates;
/** Enumerate for different types of Local Orbital Frames.
* @author Luc Maisonobe
*/
public enum LOFType {
/** Constant for TNW frame
* (X axis aligned with velocity, Z axis aligned with orbital momentum).
* <p>
* The axes of this frame are parallel to the axes of the {@link #VNC} frame:
* <ul>
* <li>X<sub>TNW</sub> = X<sub>VNC</sub></li>
* <li>Y<sub>TNW</sub> = -Z<sub>VNC</sub></li>
* <li>Z<sub>TNW</sub> = Y<sub>VNC</sub></li>
* </ul>
*
* @see #VNC
*/
TNW {
/** {@inheritDoc} */
protected Rotation rotationFromInertial(final PVCoordinates pv) {
return new Rotation(pv.getVelocity(), pv.getMomentum(),
Vector3D.PLUS_I, Vector3D.PLUS_K);
}
},
/** Constant for QSW frame
* (X axis aligned with position, Z axis aligned with orbital momentum).
* <p>
* This frame is also known as the {@link #LVLH} frame, both constants are equivalent.
* </p>
* <p>
* The axes of these frames are parallel to the axes of the {@link #VVLH} frame:
* <ul>
* <li>X<sub>QSW/LVLH</sub> = -Z<sub>VVLH</sub></li>
* <li>Y<sub>QSW/LVLH</sub> = X<sub>VVLH</sub></li>
* <li>Z<sub>QSW/LVLH</sub> = -Y<sub>VVLH</sub></li>
* </ul>
*
* @see #LVLH
* @see #VVLH
*/
QSW {
/** {@inheritDoc} */
protected Rotation rotationFromInertial(final PVCoordinates pv) {
return new Rotation(pv.getPosition(), pv.getMomentum(),
Vector3D.PLUS_I, Vector3D.PLUS_K);
}
},
/** Constant for Local Vertical, Local Horizontal frame
* (X axis aligned with position, Z axis aligned with orbital momentum).
* <p>
* This frame is also known as the {@link #QSW} frame, both constants are equivalent.
* </p>
* <p>
* The axes of these frames are parallel to the axes of the {@link #VVLH} frame:
* <ul>
* <li>X<sub>LVLH/QSW</sub> = -Z<sub>VVLH</sub></li>
* <li>Y<sub>LVLH/QSW</sub> = X<sub>VVLH</sub></li>
* <li>Z<sub>LVLH/QSW</sub> = -Y<sub>VVLH</sub></li>
* </ul>
*
* @see #QSW
* @see #VVLH
*/
LVLH {
/** {@inheritDoc} */
protected Rotation rotationFromInertial(final PVCoordinates pv) {
return new Rotation(pv.getPosition(), pv.getMomentum(),
Vector3D.PLUS_I, Vector3D.PLUS_K);
}
},
/** Constant for Vehicle Velocity, Local Horizontal frame
* (Z axis aligned with opposite of position, Y axis aligned with opposite of orbital momentum).
* <p>
* The axes of this frame are parallel to the axes of both the {@link #QSW} and {@link #LVLH} frames:
* <ul>
* <li>X<sub>VVLH</sub> = Y<sub>QSW/LVLH</sub></li>
* <li>Y<sub>VVLH</sub> = -Z<sub>QSW/LVLH</sub></li>
* <li>Z<sub>VVLH</sub> = -X<sub>QSW/LVLH</sub></li>
* </ul>
*
* @see #QSW
* @see #LVLH
*/
VVLH {
/** {@inheritDoc} */
protected Rotation rotationFromInertial(final PVCoordinates pv) {
return new Rotation(pv.getPosition(), pv.getMomentum(),
Vector3D.MINUS_K, Vector3D.MINUS_J);
}
},
/** Constant for Velocity - Normal - Co-normal frame
* (X axis aligned with velocity, Y axis aligned with orbital momentum).
* <p>
* The axes of this frame are parallel to the axes of the {@link #TNW} frame:
* <ul>
* <li>X<sub>VNC</sub> = X<sub>TNW</sub></li>
* <li>Y<sub>VNC</sub> = Z<sub>TNW</sub></li>
* <li>Z<sub>VNC</sub> = -Y<sub>TNW</sub></li>
* </ul>
*
* @see #TNW
*/
VNC {
/** {@inheritDoc} */
protected Rotation rotationFromInertial(final PVCoordinates pv) {
return new Rotation(pv.getVelocity(), pv.getMomentum(),
Vector3D.PLUS_I, Vector3D.PLUS_J);
}
};
/** Get the transform from an inertial frame defining position-velocity and the local orbital frame.
* @param date current date
* @param pv position-velocity of the spacecraft in some inertial frame
* @return transform from the frame where position-velocity are defined to local orbital frame
*/
public Transform transformFromInertial(final AbsoluteDate date, final PVCoordinates pv) {
// compute the translation part of the transform
final Transform translation = new Transform(date, pv.negate());
// compute the rotation part of the transform
final Rotation r = rotationFromInertial(pv);
final Vector3D p = pv.getPosition();
final Vector3D momentum = pv.getMomentum();
final Transform rotation =
new Transform(date, r, new Vector3D(1.0 / p.getNormSq(), r.applyTo(momentum)));
return new Transform(date, translation, rotation);
}
/** Get the rotation from inertial frame to local orbital frame.
* @param pv position-velocity of the spacecraft in some inertial frame
* @return rotation from inertial frame to local orbital frame
*/
protected abstract Rotation rotationFromInertial(PVCoordinates pv);
}