We use the notation Cfromto to denote a coordinate transformation matrix from one coordinate frame (designated by “from”) to another coordinated frame (designated by “to”). For example,
CECIENU denotes the coordinate transformation matrix from earth-centered inertial (ECI) coordinates to earth-fixed east-north-up (ENU) local coordinates and
CRPYNED denotes the coordinate transformation matrix from vehicle body-fixed roll-pitch-yaw (RPY) coordinates to earth-fixed north-east-down (NED) coordinates.
Coordinate transformation matrices satisfy the composition rule
CBCCAB = CAC,
where A, B, and C represent different coordinate frames.
What we mean by a coordinate transformation matrix is that if a vector v has the representation
in XYZ coordinates and the same vector v has the alternative representation
in UVW coordinates, then
where “XYZ” and “UVW” stand for any two Cartesian coordinate systems in three-dimensional space.
The components of a vector in either coordinate system can be expressed in terms of the vector components along unit vectors parallel to the respective coordinate axes. For example, if one set of coordinate axes is ...