Strapdown Airborne Gravimetry Using a Combination of Commercial Software and Stable-Platform Gravity Estimates

For the past two decades, airborne gravimetry using a Strapdown Inertial Measurement Unit (SIMU) has been producing gravity estimates comparable to the traditional stable-platform single-axis gravimeters. The challenge has been to control the long term drift of the IMU sensors, propagating into the long-wavelengths of the gravity estimates. This has made the stable-platform approach the preferred method for geodetic applications. In the summer of 2016, during a large airborne survey in Malaysia, a SIMU system was flown alongside a traditional LaCoste&Romberg (LCR) gravimeter. The SIMU observations were combined with GNSS observations using the commercial software product “Inertial Explorer” from NovAtel’s Waypoint software suite, and it is shown how gravity estimates can be derived from these results. A statistical analysis of the crossover differences yields an RMS error of 2.5 mGal, which is comparable to the results obtained from the LCR gravimeter. The properties of the SIMU and LCR systems are compared and a merging of the two is performed. A statistical analysis of the crossover differences of the merged product yields an RMS error of 1.3 mGal. These results indicate that the properties of the two units are complementary and that a combination of the two can result in improved gravity estimates.