Accession Number : ADA496707


Title :   An Investigation Into the Feasibility of Using a Modern Gravity Gradient Instrument for Passive Aircraft Navigation and Terrain Avoidance


Descriptive Note : Master's thesis


Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT


Personal Author(s) : Rogers, Marshall M


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a496707.pdf


Report Date : Mar 2009


Pagination or Media Count : 180


Abstract : Recently, Gravity Gradient Instruments (GGIs) - devices which measure the spatial derivatives of gravity, have improved remarkably due to development of accelerometer technologies. Specialized GGIs are currently flown on aircraft for geological purposes in the mining industries. As such, gravity gradient data is recorded in flight and detailed gradient maps are created after post mission processing. These maps, if stored in a database onboard an aircraft and combined with a GGI, form the basis for a covert navigation system using a map matching process. This system is completely passive and essentially unjammable. To determine feasibility of this method, a GGI sensor model was developed to investigate signal levels at representative flight conditions. Aircraft trajectories were simulated over modeled gravity gradient maps to determine the utility of flying modern GGIs in the roles of navigation and terrain avoidance. It was shown that the GGI based map-matching navigation system can likely provide a marked improvement over a non-aided INS but is limited by decreasing gravity gradient strength at higher altitudes, particularly over smooth terrain. Additionally, GGI output rate and bandwidth limitations, along with the inverse nature of the terrain avoidance problem, rendered GGI aided terrain avoidance unfeasible for the time being.


Descriptors :   *TERRAIN AVOIDANCE , *AIR NAVIGATION , AIRCRAFT , MODELS , ACCELEROMETERS , RATES , PASSIVE SYSTEMS , TERRAIN , MINING ENGINEERING , NAVIGATION , MISSIONS , HIGH ALTITUDE , INFLIGHT , COVERT OPERATIONS , INSTRUMENTATION , GRAVITY , MAPS , BANDWIDTH , MATCHING , TRAJECTORIES , GRADIENTS , OUTPUT , DATA BASES , SIGNAL PROCESSING


Subject Categories : Navigation and Guidance


Distribution Statement : APPROVED FOR PUBLIC RELEASE