System for gravity map aided navigation

A method, comprising:

• identifying, by a data processing system, coupled with memory, based on an estimated position of the data processing system, a value of gravity from a plurality of values of gravity mapped to a plurality of positions;
• determining, by the data processing system, an altitude of the data processing system based on at least the value of gravity and a force measured by an accelerometer of the data processing system;
• comparing, by the data processing system, the altitude with a reference altitude to identify an altitude error;
• and
• determining, by the data processing system, a position of the data processing system based on the altitude error.

An inertial navigation system, comprising:

• an accelerometer to measure a force;
• a gyroscope to measure a rotational velocity;
• and
• processing circuitry to:
• retrieve, based on an estimated position of a platform including the inertial navigation system, a value of gravity from a plurality of values of gravity mapped to a plurality of positions;
• determine an altitude of the platform based on at least the value of gravity, the force, and the rotational velocity;
• compare the altitude with a reference altitude to determine an altitude error;
• and
• determine a position of the platform based on the altitude error.