Methodology of Airborne Gravimetry Surveying and Strapdown Gravimeter Data Processing

Abstract

The paper presents a methodology of preparing and conducting airborne gravimetry survey using an inertial measuring unit (IMU) or strapdown inertial navigation system as airborne gravimeter. We also discuss the key aspects of developing appropriate postprocessing algorithms and software and their application to gravimeter raw data processing. Solving the strapdown inertial airborne gravimetry problem, we use readings of the IMU sensors (accelerometers and gyroscopes) as primary information. The second equally important source of information is raw (pseudorange, Doppler pseudorange rate, and carrier phase) measurements from the GNSS receivers on board the aircraft and on the ground. The developed methodology, algorithms, and practical recommendations presented in the paper are based on the authors’ long-term experience in airborne gravimetry.

IMU and GNSS Postprocessing for High-Resolution Strapdown Airborne Gravimetry

“…The flights were characterized by extreme vertical accelerations up to 2.5 g (Figure 1), which appears to be one of the first cases in airborne gravimetry (see also results in [4]). In Figure 1, the gravimeter's IMU roll and pitch angles (estimated in stage 4 of the methodology) are also shown, indicating exceptionally strong dynamic conditions during the flight.…”

“…The campaign was based on using a helicopter-type UAV (the photo is presented in [4]). Several flights were flown at a constant height of 340 m above the WGS-84 ellipsoid at an average speed of 25 m/s.…”

“…Over the past three years, Lomonosov MSU has developed postprocessing algorithms for strapdown airborne gravimetry [4]. The objective of this study is to determine the best spatial resolution of aerogravity data with the developed algorithms in surveys based on a small aircraft and UAV.…”

“…The developed alignment algorithm admits angular motion of the gravimeter during aircraft standstill (caused by wind at the airfield or other external disturbances). During this step, the biases of IMU accelerometers are also determined using a calibration procedure [4].…”