Name

CL_fr_qswMat — Local orbital frame (q,s,w) definition in an inertial frame

Calling Sequence

   [M] = CL_fr_qswMat(pos_car,vel_car)
   
   

Description

  • Given satellite's position and velocity vectors in a geocentric inertial frame, this function computes the frame transfer matrix from the inertial frame to the local orbital frame QSW.
  • The QSW local orbital frame is defined as follows:

    origin: center of gravity of the satellite

    q: a unit vector from the planet center towards the satellite

    w: a unit vector in the direction of the osculating orbit's kinetic moment

    s: a unit vector chosen so that qsw is a direct orthonormal frame

  • To convert a vector pos_car to pos_qsw, you can use the (hyper)matrix M : pos_qsw = M*pos_car

    To convert a vector pos_qsw to pos_car, you can use the (hyper)matrix M' : pos_car = M'*pos_qsw

    For big hypermatrixes, it is faster to use the functions CL_fr_qsw2inertial and CL_fr_inertial2qsw

  • Last update : 07/11/2007

Parameters

pos_car:

satellite's cartesien position in a geocentric inertiel frame [m] (3xN)

vel_car:

satellite's cartesien velocity in a geocentric inertiel frame [m/s] (3xN)

M :

frame transfer matrix from an inertial frame to the QSW local frame (3x3xN)

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 (Les Reperes orbitaux locaux)

Authors

CNES - DCT/SB

See also

CL_fr_qsw2inertial, CL_fr_inertial2qsw, CL_fr_tnwMat, CL_fr_inertial2tnw, CL_fr_tnw2inertial

Examples

// Inertial to QSW :
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]'
[M] = CL_fr_qswMat(pos_car,vel_car)
pos_qsw = M*pos_car;

// QSW to inertial :
pos_car = M'*pos_qsw;