Coordinate System
Coordinate system defined by the local vertical and the directions of geographic north and east at a specific point on the surface of the earth. The local level frame provides a convenient reference for terrestrial navigation and attitude control of vehicles. The frame moves with the platform but its axes remain aligned with the local gravity vector and the rotation of the planet.
Orthogonal Orientation
The primary axes are typically designated as north and east axes along with the down direction. Within the local level frame, the down axis coincides with the gravity vector while the north axis points toward the geographic pole. This arrangement allows for the direct measurement of pitch and roll relative to the horizon and the meridian.
Transformation Matrix
Computers use mathematical rotations to convert sensor data from the body frame into this geographic reference. Maintaining the local level frame requires constant updates to account for the movement of the vehicle over the curved surface of the earth. These calculations involve the radius of curvature and the current velocity to ensure that the axes remain correctly aligned during transit.
This continuous re-alignment is essential for preventing errors in the perceived orientation of the vehicle as it traverses long distances.
Navigational Utility
Pilots and navigators rely on this frame to interpret their position relative to maps and charts.
