Gravity Gradiometry and Map Matching

Inertial navigation systems (INS) offer passive, all-weather, and undeniable navigation information, which military customers often view as especially appealing strengths. Unfortunately, Airmen and engineers still struggle with INS's drifting position errors, and navigation aids generally detract from INS's strengths. At this year's Air, Space, and Cyberspace in the 21st Century Conference, the Chief of Staff of the Air Force identified the Global Positioning System (GPS) as a widely-known and exploitable vulnerability, saying that it's critical the Joint force reduce GPS dependence. Recent advances provide an opportunity for gravity gradient instruments (GGI), which measure spatial derivatives of the gravity vector, to aid an INS and preserve its strengths. This thesis shows that a GGI and map matching enhanced (GAME) INS improves navigation accuracy, presents the conditions that make GAME feasible for aircraft, and identifies opportunities for improvement. The methodology includes computer models and algorithms, where a GGI and map matching aid an INS through a Kalman filter. Simulations cover different terrains, altitudes, velocities, flight durations, INS drifts, update rates, components of the gravity gradient tensor, GGI and map noise levels, map resolutions, and levels of interpolation. Although GAME with today's technology only appears worthwhile for long range and long endurance flights, the technologies expected in 10 years promise a broad spectrum of scenarios where GAME potentially provides great returns on investments and dominates the market for secure and covert navigation.

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