Acceleration Force
Direction and magnitude of the acceleration exerted by the earth on a mass at a specific location. The gravity vector acts as the primary reference for determining the local vertical in inertial navigation and stabilization systems. The total force combines the effects of mass gravitation and the centrifugal force generated by the rotation of the planet.
Orientation Reference
Accelerometers measure the projection of this force onto their sensitive axes to calculate the tilt of a device. By analyzing the components of the gravity vector, a system determines the pitch and roll angles relative to the horizon. This static measurement remains valid only when the sensor is not subjected to additional linear accelerations.
Local Variation
Density changes in the crust and the non-spherical shape of the earth cause small fluctuations in the local strength of the field. Precise models of the gravity vector account for these anomalies to improve the accuracy of position calculations in long-range navigation. Standard gravity is defined at sea level but the actual value must be adjusted for altitude and geographic coordinates.
These corrections prevent the accumulation of vertical velocity errors in the navigation solution over time.
Calibration Datum
High-precision leveling of a sensor mount relies on this constant natural force. The gravity vector provides a stable and universal stimulus for verifying the zero-offset of inertial instruments.
