Calculate Earth-centered Earth-fixed (ECEF) position from geodetic latitude, longitude, and altitude above planetary ellipsoid
The LLA to ECEF Position block converts geodetic latitude , longitude , and altitude above the planetary ellipsoid into a 3-by-1 vector of ECEF position . Latitude and longitude values can be any value. However, latitude values of +90 and -90 may return unexpected values because of singularity at the poles. The ECEF position is calculated from geocentric latitude at mean sea-level (λs) and longitude using:
where geocentric latitude at mean sea-level and the radius at a surface point (rs) are defined by flattening , and equatorial radius in the following relationships.
Specifies the parameter and output units:
This option is only available when Planet model is set to Earth (WGS84).
Specifies the planet model to use: Custom or Earth (WGS84).
Specifies the flattening of the planet. This option is only available with Planet model set to Custom.
Specifies the radius of the planet at its equator. The units of the equatorial radius parameter should be the same as the units for altitude. This option is only available with Planet model set to Custom.
|2-by-1 vector||Contains the geodetic latitude and longitude, in degrees.|
|Scalar||Contains the altitude above the planetary ellipsoid.|
|3-by-1 vector||Contains the position in ECEF frame, in same units as altitude.|
The planet is assumed to be ellipsoidal. To use a spherical planet, set the Flattening parameter to zero.
The implementation of the ECEF coordinate system assumes that the origin is at the center of the planet, the x-axis intersects the Greenwich meridian and the equator, the z-axis being the mean spin axis of the planet, positive to the north, and the y-axis completes the right-handed system.
Stevens, B. L., and F. L. Lewis, Aircraft Control and Simulation, John Wiley & Sons, New York, 1992.
Zipfel, P. H., Modeling and Simulation of Aerospace Vehicle Dynamics, AIAA Education Series, Reston, Virginia, 2000.
"Atmospheric and Space Flight Vehicle Coordinate Systems," ANSI/AIAA R-004-1992.