An accurate gravity compensation method for high-precision airborne POS

Remote sensing processing requires precise motion information provided by position and orientation system (POS), whereas gravity disturbance is normally ignored in POS solution procedure. For high-precision POS, gravity disturbance becomes a significant error source with decisive effects on the accuracy of POS. In this paper, an accurate gravity compensation method is proposed, which includes the gravity disturbance as the error states of POS Kalman filter, and the appropriate model of gravity disturbance is constructed by time series analysis coupled with the direct difference method. In verifying our gravity compensation method, POS and digital still camera combined flight experiment was conducted in 2011, where the aerial triangulation output of images was taken as a reference to evaluate the POS accuracy. Results show that the horizontal attitude accuracy of high-precision POS (0.01 °/h gyro drift) is 0.0031 ° under differential Global Positioning System condition, and the proposed method has a better performance comparable to other gravity compensation methods.