Airborne Vector Gravimetry Method Based on Independent Gyros Observations

In airborne vector gravimetry algorithms based on SINS/GNSS integrated navigation, the ultimate accuracy of horizontal attitude resolution is primarily constrained by the combined effects of horizontal gravity disturbances and accelerometer measurement errors. Gravity disturbances along the survey line enter the error propagation equations of the strapdown inertial navigation system (SINS) via the sensitivity of accelerometers, forming a closed-loop coupled error propagation chain related to horizontal gravity disturbances. This increases the difficulty of error processing and gravity vector determination. To address this issue, this paper proposes an airborne vector gravimetry method based on independent gyroscopic observation. The method introduces an independent gyros-based attitude determination approach into the traditional SINS/GNSS integrated navigation algorithm. It utilizes the gyroscope assembly of the SINS to independently update the attitude in the inertial frame. The geographic position and time information from GNSS are then used to transform this inertial-frame attitude to the navigation frame for use. A key feature of this method is that it does not employ accelerometer measurements during the attitude update process, thereby avoiding the influence of accelerometer errors and gravity disturbances on the horizontal attitude and achieving decoupling of the closed-loop error propagation chain. Building upon this foundation, the study investigates the linear mapping relationship between the horizontal attitude errors independently resolved by the gyroscope and the horizontal gravity disturbances. Error compensation for airborne gravity vector measurements is performed using gravity anomaly information derived from the EGM2008 model, with both simulated and field data employed for validation. The airborne gravity survey experiments demonstrate that the internal consistency accuracies for the eastward, northward, and upward gravity anomaly components are 1.53 mGal, 2.34 mGal, and 0.59 mGal, respectively, with a spatial resolution of approximately 3 km. This method significantly enhances the decoupling capability between accelerometer measurement errors and gravity disturbances, thereby improving the measurement accuracy of horizontal gravity components.