Intro
The Local Vertical, Local Horizontal (LVLH) frame is a spacecraft-centered orbital reference frame used to describe a vehicle’s position and orientation relative to its orbit and Earth.
Unlike Earth-fixed coordinate systems such as ECEF, the LVLH frame moves with the spacecraft as it travels along its orbit.
LVLH frames are commonly used for:
- spacecraft attitude control
- orbital navigation
- rendezvous and docking
- relative motion analysis
LVLH Axes (Earth-Pointing)
For an Earth-pointing LVLH frame:
| Axis | Direction | Meaning |
|---|---|---|
| X-axis | Along velocity vector | Direction of orbital travel |
| Y-axis | Orbit normal direction | Perpendicular to orbital plane |
| Z-axis | Toward Earth’s center | Local vertical / nadir direction |
LVLH Earth-Pointing Frame
- The frame moves with the spacecraft as it orbits Earth.
- The X-axis points in the direction of travel.
- The Z-axis points toward Earth’s center (nadir).
- The Y-axis completes the right-handed coordinate system.
Applications
LVLH frames are used for:
- spacecraft attitude determination
- pointing and control systems
- formation flying
- docking operations
- orbital maneuver planning