Abstract The strapdown inertial scalar gravimetry (SISG) has become one of the main methods for measuring marine gravity. SIGS requires specific force, attitude, velocity, and position information for gravimetry. The attitude can be obtained by the strapdown inertial navigation system/global navigation satellite system (SINS/GNSS) integration, and the displacement information comes from GNSS or SINS/GNSS. Therefore, based on the different sources of displacement information, shipborne SISG can be divided into two modes. Namely, the gravimetry method of different parameter sources (DPGM) based on displacement information of GNSS and the attitude of SINS/GNSS, as well as the full parameter gravimetry method (FPGM) based on the attitude and displacement information of SINS/GNSS. Since the accuracy of GNSS can meet the requirements for gravimetry, the theoretical studies and applications of DPGM are more common. For FPGM, this idea is more often used in underwater applications (SINS/ doppler velocity log (SINS/DVL), etc.). However, it rarely appears in shipborne applications. Moreover, there is relatively little theoretical analysis on FPGM. In fact, FPGM also has certain application prospects due to the high accuracy. Based on this, this article first provides the measurement model and steps of FPGM, and conducts the theoretical analysis of FPGM. The comparison is made with DPGM from the perspective of error terms. And it is pointed out that FPGM has better potential for anti-interference improvement than DPGM. Then, from the perspective of application, we propose the investigated linear robust Kalman filter (LRKF) based on Huber-M estimation without traversing all dimensions and introduce the horizontal acceleration and bias corrections to improve FPGM. Finally, the optimized FPGM (OFPGM) is obtained. The results of lake and sea tests show that FPGM has certain research value. And OFPGM has higher performance in high dynamic condition and when GNSS occurs interference, which is more suitable for offshore measurement.
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