A Method for Underwater Real-time Gravimetry

Underwater gravity information plays a significant role in deepwater oil and gas exploration and submersible-aided navigation. Real-time monitoring of gravimeter status is required during underwater gravimetry. Real-time gravity anomaly data can improve the effectiveness of resource exploration, and the aided navigation of submergence vehicle also requires real-time gravimetry results, so the research of real-time underwater gravimetry methods is crucial. We analyzed the underwater gravimetry mathematical model and found that sensors which provide formula variables such as strapdown inertial navigation system (SINS), doppler velocity log (DVL), depth gauge (DG), and ultrashort baseline acoustic positioning system (USBL) can output data in real time. Thus, a new method for underwater real-time gravimetry was proposed for underwater gravimeter application environment. By dynamically adjusting the model of the integrated navigation methods, the three integrated navigation modes of SINS/DVL, SINS/USBL and SINS/DG are transformed in real time according to the actual sensor data input, providing the gravimetry data processing including velocity, position, and attitude navigation information for gravimetry data processing. The algorithm is validated using offline data from sea trials. The experimental results demonstrate that the method can obtain high-quality gravimetry data in real time with an internal compliance accuracy of 0.85~0.95mGal for processing the measurement line, which provides theoretical support for the practical development of the underwater gravimetric system and the construction of the algorithm system.