New Results from Strapdown Airborne Gravimetry Using Temperature Stabilisation

Abstract

In recent years, the use of a strapdown Inertial Measurement Unit (IMU) for airborne gravimetry has proven itself to be an accurate and resilient measurement system, improving the operational flexibility. The main concern is erroneous long-wavelength information in the resulting estimates, which is suspected to originate from uncompensated long-term drift of the accelerometers, probably originating from temperature variation. For this reason, iMAR navigation has designed a temperature stabilisation box, which allows for temperature stabilisation of their IMU systems. On a regional airborne gravity survey over the Kattegat Sea between Denmark and Sweden, such a temperature stabilised strapdown IMU was operated alongside a traditional spring-type platform-stabilised gravity system from ZLS. An analysis of the difference in gravity estimates at cross-over locations yielded a mean value of −0.3 mGal for the iMAR system with an indicated accuracy of 1.0 mGal. The temperature stabilisation unit therefore effectively limits the accelerometer drift and improves the long-wavelength information. However, a straightforward merging approach, adjusting the line-based mean values of the iMAR estimates to match that of the ZLS estimates, improved the accuracy to 0.8 mGal. This indicates that the long-wavelength information of the stabilised-platform system is still superior to that of the strapdown system.

Airborne Absolute Gravimetry With a Quantum Sensor, Comparison With Classical Technologies

“…Two conventional airborne gravimeters were additionally installed on board the aircraft. The first was an older L&R S‐type gravimeter mounted on a two‐axis damped platform (Valliant, 1992), the second a navigation‐grade Inertial Measurement Unit (IMU) with temperature stabilization from iMAR Navigation, mounted in a strapdown configuration (Jensen et al., 2019). A photograph of these gravimeters deployed in the aircraft is shown in Figure 1.…”

Epoch-Based Height Reference System for Sea Level Rise Impact Assessment on the Coast of Peninsular Malaysia

“…Two iMAR units were onboard for the 2022 survey, and they were processed using completely different software and methods. The DTU processing of the iMAR RQH unit was performed using an 18-state Kalman Filter/Optimal smoother setup [44], with 3rd order Markov model parameters fitted on a daily base depending on flight conditions. The TUD processing, on the other hand, was performed using an independent pre-processing for precise positions, roll, pitch, and heading, followed by using the IMU accelerometer triad data as a gravity sensor, filtering it in a 120 s (full wavelength) filter, similar to standard LC&R processing [45].…”

Evaluation of the Prospects and Resolution of Global Ultra-High-Degree Models of the Earth's Gravitational Field

“…Оценки первых авторов показывают превосходство новой альтиметрической модели гравитационного поля DTU17 над классической моделью EGM2008 по результатам сравнения с аэрогравиметрической съемкой в проливе Каттегат [Jensen et al, 2019]. Стандартные отклонения составили 1.8 мГал для модели DTU17 и 2.1 мГал для модели EGM2008, а максимальные отклонения достигали значений 10.2 мГал и 17.6 мГал для моделей DTU17 и EGM2008 соответственно.…”

“…Оценки моделей, выполняемые разными исследователями (см., например, [Непоклонов, Максимова, Абакушина, 2016;Конешов и др., 2018;Jensen et al, 2019]), как правило, характеризуют общее качество высокостепенных модельных решений в интересующем регионе. Такие оценки показывают, что повышение степени разложения геопотенциала не всегда обеспечивает достоверность модельного поля.…”