The universal gravity module for enhanced submarine navigation

With a view toward current and future submarine missions requiring operations in the littoral and accurate navigation under covert conditions, Navigation and Gravity Systems (NGS) of Lockheed Martin Federal Systems has developed the Universal Gravity Module (UGM). The UGM is a low cost modular add-on to an existing submarine navigator which, through gravity measurements, infuses new capabilities into undersea warfare, and is applicable to existing and future fleet ballistic missile and attack submarines. The capabilities provided are as follows: Gravity Passive Navigation (PN)-provides high accuracy navigation for unlimited periods without the need for periodic surfacing or active emissions in order to obtain a position or velocity fix. This technique provides the ultimate in stealth for all submersibles. Terrain Estimation (TE)-provides accurate real-time displays of the local terrain without the need for active emission. This enables the submarine to conduct safe covert operations close to the sea bed. Such maneuvers as entries and exits from harbors can also be safely and covertly executed. This paper provides an overview of the UGM, including a description of the gravity sensors and the algorithms which provide the passive navigation and terrain estimation capabilities. Test results of the passive navigation and terrain estimation capabilities are also presented