def getQpqw2eci(self):
"""Returns the frame transformation matrix from the PQW (co-planar)
frame to the earth-centered inertial (ECI) frame, w.r.t. J2000.
"""
w = rot.Z(self.w_rad)
i = rot.X(self.i_rad)
O = rot.Z(self.O_rad)
return (w.dot(i).dot(O)).transpose()
def test_example4p7(self):
O = rot.Z(40 * pi / 180)
i = rot.X(30 * pi / 180)
w = rot.Z(60 * pi / 180)
wiO_act = w.dot(i).dot(O)
wiO_ref = numpy.array([[-0.099068, 0.89593, 0.43301],
[-0.94175, -0.22496, 0.25],
[0.32139, -0.38302, 0.86603]])
dWIO = (wiO_ref - wiO_act).reshape((9, ))
self.assertTrue(dWIO.dot(dWIO)**0.5 < 1e-4)
def getQpqw2eci(self, t_dt=None):
"""Returns a time-varying tranformation matrix that converts vectors
from the PQW (co-orbital) frame to the earth-centered inertial (ECI)
frame (w.r.t. the J2000 epochal orientation). This includes the RAAN
precession and AoP procession rates induced by the J2 harmonic.
"""
w = rot.Z(self.getAop(t_dt))
i = rot.X(self.i_rad)
O = rot.Z(self.getRaan(t_dt))
return (w.dot(i).dot(O)).transpose()
def getQecf2enu(rSiteLla_radm):
"""Returns a transformation matrix that converts an ECF vector to ENZ as
perceived from a site at the given lat/lon/alt location. Note that this
is a frame rotation only--relative range requires user subtraction.
"""
Quen2enu = numpy.array([[0, 1, 0], [0, 0, 1], [1, 0, 0]])
ry = rot.Y(-rSiteLla_radm[0])
rz = rot.Z(rSiteLla_radm[1])
return Quen2enu.dot(ry).dot(rz)
def getQeci2ecf(t_dt):
"""Returns a 3x3 numpy.array that defines a transformation (at this level of
fidelity, just a Z rotation) from the ECI to ECF frame at the given
*datetime.datetime* value.
"""
return rot.Z(getGmst(t_dt))
def test_Z(self):
v = rot.Z(0.5 * pi).dot(numpy.array([1, 0, 0]))
self.assertTrue(norm(v - numpy.array([0, -1, 0])) < 1e-8)