Name
CL_fr_inertial2tnw — Inertial to local orbital frame (t,n,w) vector transformation
Calling Sequence
[vect_tnw] = CL_fr_inertial2tnw(pos_car,vel_car,vect_geo)
Description
-
Given the vector vect_geo expressed in a geocentric inertial frame, this function computes
its coordinates vect_tnw in the local orbital frame (t,n,w) defined
by satellite's position (pos_car) and velocity (vel_car) in the geocentric inertial frame.
- The TNW local frame is defined as follows:
origin: center of gravity of satellite
t: unit vector in the direction of satellite's velocity
w: unit vector of the kinetic moment of the osculating orbit
n: unit vector chosen so TNW is a direct orthonormal frame

- Last update : 25/07/2007
Parameters
- pos_car:
satellite's cartesien position in a geocentric inertial frame [m] (3xN)
- vel_car:
satellite's cartesien velocity in a geocentric inertial frame [m/s] (3xN)
- vect_geo:
vector cartesien coordinates in a geocentric inertial frame (3xN)
- vect_tnw:
vector vect_geo coordinates in the local orbital frame (t,n,w) (3xN)
Bibliography
1 Mecanique spatiale, CNES - Cepadues 1995, Tome I, section 10.2.2.3 (Definition du Repere orbital local)
2 CNES - MSLIB FORTRAN 90, Volume O (mo_geo_tnw)
Examples
// Example 1
pos_car = [- 700700.,5.325E-11,6.718E-11;- 700700.,5.325E-11,6.718E-11]'
vel_car = [- 2.919E-12,- 14807.462,- 18682.367;- 2.919E-12,- 14807.462,- 18682.367]'
vect_geo = [1,0,0;1,1,1]'
[vect_tnw] = CL_fr_inertial2tnw(pos_car,vel_car,vect_geo)