Ship-Borne Marine Absolute Gravimetry via Sensors Ultratight Fusion of an Atomic Gravimeter and a Classical Accelerometer

Abstract

Atomic gravimeters have been developed rapidly and been widely used in recent years, while their implementation for ship-borne marine applications is still limited. The harsh vibration environment destroys the atomic interference fringe, making the extraction of absolute gravity more challenging. An ultratight fusion scheme of an atomic gravimeter and a classical accelerometer was therefore proposed for ship-borne marine absolute gravimetry. Atomic gravimeters can realize very sensitive and long-time stable absolute measurement without mechanical wear and with zero drift, while a classical accelerometer delivers continuous measurement with large bandwidth and wide dynamic range. In the fusion, the signal from the classical gravimeter was first recovered, and then its weighted coupling coefficients were determined. Vibration phase compensation was achieved for the atomic gravimeter, while the weighted interference fringe was reconstructed. Extended Kalman filter was used to estimate the drift of the classical accelerometer. The data from these two types of sensors were fused to filter and correct the output of absolute acceleration. Ultimately, continuous and high-precision absolute gravimetry could be realized. A gravimetry experiment with a marine survey of around 44 h was carried out in order to test the effectiveness of the scheme, and the gravity data at a sampling rate of 1 Hz was obtained. After comparison with data from a relative gravimeter on the same ship, the evaluation revealed an external coincidence precision of 0.89 mGal. The measurement of four repeated survey lines in the east-west direction was evaluated to obtain an internal coincidence precision of 0.79 mGal. Besides, the same group of data is compared with the loose fusion method, which proves the superiority of the ultratight fusion method quantitatively.

Topics & Concepts