High Accuracy Gravity Disturbance Surveys Using an Astro Inertial Navigation System With Differential GPS

Ted Hagstrom, Mitch Miller, Doug Atkinson, Ron Davis

Abstract:	The ability to perform highly accurate gravity surveys over both accessible and inaccessible terrain’s at low cost is highly desirable for both commercail and military purposes. Based on analysis data obtained from using actual flight data from the astroinertial navigation system (AINS) on the B-2 air vehicle, it has been demonstrated that the AINS or a comparable system could be used to perform economical highly accurate surveys to meet these requirements. Thiscapability exits primarily because the following reasons: . The AINS consists of a highly accurate astro tracker which corrects the platform tilts, therebymaking it possible to differentiate the platform tilts from accelerometer null biases l Software has been developed that archives the AINS key instrument data so that it can be reprocessed in an analysis laboratory using highly accurate GPS truth data to extract the various extraneous error states to determine the three gravity disturbance vectors l The position truth using GPS set corrected for carrier phase is presently available l The analysis tools necessary to perform the data reduction are developed and hosted on PC’s making the reduction process inexpensive The capability to use an AINS is critical from the standpoint of robustness and cost because of the substantial reduction in time on station required to survey the terrain. This paper presents some examples of predictions using the analysis software on an actual B-2 air vehicle flight. The gravity disturbances obtained using the same processing on data from an equivalent onboard inertial platform system without a tracker on the same flight is also presented and its performance compared.. An detailed overview of the requirements and approach necessary to utilize this process for worldwide surveys is presented. The system could be used in an aircraft, ships, or ground vehicle. The recommended approach uses an AINS and requires a GPS ground station to generate differential GPS “truth” references for the PTS. The analysis tools are hosted on PC’s, making the data reduction process mobile and highly efficient. The resultant process can be applied to provide highly accurate survey data, the wavelengths of the data can be modified by controlling the time on station. The process is highly robust and reliable.
Published in:	Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997) June 30 - 2, 1997 Albuquerque, NM
Pages:	237 - 243
Cite this article:	Hagstrom, Ted, Miller, Mitch, Atkinson, Doug, Davis, Ron, "High Accuracy Gravity Disturbance Surveys Using an Astro Inertial Navigation System With Differential GPS," Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997), Albuquerque, NM, June 1997, pp. 237-243.
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