Definitions for the VNC, VVLH and LVLH coordinate frames are given in the following sections:
VNC Frame
In the VNC (Velocity - Normal - Co-normal) coordinate frame:
- the X axis is along the velocity vector
- the Y axis is along the orbit normal (
)
- the Z axis completes the orthogonal triad (
)
VVLH Frame
In the VVLH (Vehicle Velocity, Local Horizontal) coordinate frame:
- the Z axis is along the negative position vector
(nadir)
- the Y axis is along the negative orbit normal (
)
- the X axis is toward velocity (
)
The following figure illustrates VVLH axes:
LVLH Frame
In the LVLH (Local Vertical, Local Horizontal) coordinate frame:
- the X axis is along the position vector
(position)
- the Z axis is along the orbit normal
(orbit normal)
- the Y axis is toward velocity (
)