Attitude error compensation technology for inertial platform of airborne gravimeter based on RTS smoothing algorithm

Dynamic relative gravimeter's attitude reference of specific force measurement is based on inertial platform. In airborne gravimetry, the inertial platform must maintain its level accuracy under large acceleration. Using Schuler tuned inertial platform is one feasible scheme. But attitude errors of the platform oscillate at Schuler frequency will be excited in the presence of system error. The attitude errors of the platform increase with time and decrease the measurement accuracy of the specific force. So, the RTS smoothing algorithm is introduced to compensate for the attitude errors of the inertial platform based on the fact that gravimetric data can be processed off-line. The misalignment angle is converted to error quaternion and the mathematical compensation for the specific force measurement error of platform inertial system is realized. Finally, the effectiveness of the algorithm is verified by simulation results. The RTS smoothing has higher accuracy at the time period of the initial phase of Kalman filtering. Also the RTS smoothing has big advantages over Kalman filtering in the presence of carrier maneuvering. In the simulation's two time periods when the carrier undergoes horizontal acceleration of, the accuracy of vertical specific force improved by and respectively compared with Kalman filtering.