Moving Base INS/GPS Vector Gravimetry on a Land Vehicle
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Date
2007-12
Authors
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Journal ISSN
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Publisher
Ohio State University. Division of Geodetic Science
Abstract
The Inertial Navigation System and Global Positioning System (INS/GPS) system
has been extensively studied over several decades, mostly for the purpose of
navigation and kinematic position. Because the INS system is a ected by gravitation,
the integration de nitely needs gravity data in order to yield accurate results.
It is natural to reverse the problem and attempt a measurement of the gravity vector.
The gravimetric system based on INS/GPS shows good performances in the airborne
scenarios. Moving the system into a ground vehicle will help to improve the resolution
of the gravity estimates, considering its lower speed and altitude. However, the
system will face much more complicated dynamics and harsh observation conditions.
In this study, a two-stage extended Kalman lter based on processing noise adaptation
is used to x the position gaps and provide prior information of the Inertial
Measurement Units (IMU) errors. The kinematic acceleration is computed by both
the position method and the phase method. All these procedures improve the steadiness
and precision of the system. The advanced wavelet de-noising technique is employed
to further isolate the gravity disturbance from the observation errors in the
residuals of the novel Kalman lter, previously developed at the Ohio State University
(OSU). The nal precision of the gravity disturbance estimates is further improved
by correlatively ltering the repeated estimates in the frequency domain.
An intensive survey campaign was carried out to test the validities of these techniques.
Based on data analysis, the results show signi cant consistency (as good as
0.6mGal, STD) in the vertical component on the repeated traverses, and comparison
to control data indicates an accuracy of 2-3mGal (STD). However, it is also
determined that the control data, being interpolated from a database, have an accuracy
of approximately 3mGal (STD). Resolution of the estimated gravity disturbance
is about 2km, based on 180-s data smoothing and a vehicle speed averaging about
80km/hr. Large scale errors exist in the horizontal gravity estimates. Removing
these on the basis of extensive de
ection of the vertical control yields repeatability in
the horizontal components in the range of 2-15mGal (STD) and agreement with the
control at the level of 5-9mGal (STD).
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Description
This report was prepared for and submitted to the Graduate School of the Ohio State University as a dissertation in partial fulfillment of the requirements for the PhD degree.
The research was supported by a grant from the National Geospatia l Intelligence Agency (NMA202-98-1-1110) under the NGA University Research Initiative program. Additional assistance came from the Center for Mapping at the Ohio State University in the form of GPSVan survey and data analysis support.
The research was supported by a grant from the National Geospatia l Intelligence Agency (NMA202-98-1-1110) under the NGA University Research Initiative program. Additional assistance came from the Center for Mapping at the Ohio State University in the form of GPSVan survey and data analysis support.