Research On Data Processing And Filtering Technology Of Airborne Gravimetry

The earth’s gravity field is the inherent attribute of the earth.Obtaining accurate information of the earth’s gravity field is of great significance to the study of Earth Science,the promotion of national economic development and the construction of national defense and military.The measured value of the gravity sensor contains the gravity acceleration information and the motion acceleration component of the carrier.It is necessary to separate the motion acceleration of the carrier from the specific force acceleration,and then through the compensation of various errors,the relatively accurate gravity acceleration information can be obtained.At present,with the rapid development of measuring components and the improvement of DGNSS precision,the gravity measurement data processing method has gradually become the main factor restricting people from obtaining high-precision gravity information.The main work and innovations of this paper are as follows:1.At present,there are mainly two methods to calculate the precision of airborne gravimetry.The experimental analysis of the two methods shows that the second method is more suitable for the precision evaluation of airborne gravimetry with less repetition lines;Aiming at the problem of high-frequency noise in airborne gravity anomaly measurement,based on the previous research,this paper adds Gaussian window and flat top window to design eight kinds of window function FIR filters,and verifies the selection of filter order of Gaussian window and flat top window.The results show that Gaussian window,Hamming window and Hanning window have better filtering effect;According to the characteristics of airborne gravity anomaly data,the design steps of equiripple filter are proposed,and the equiripple filter with 6d B bandwidth as the cut-off frequency is designed.Under the same accuracy,the order of FIR filter is reduced,which can theoretically reduce the loss of measurement resolution.2.Due to the obvious time delay problem in the calculation method of Kalman filter for airborne gravimetry,the time delay problem of Kalman filter is discussed and analyzed,and the forward and inverse Kalman filter weighting algorithm is used to solve the above problem;By introducing the vertical specific force factor error term,the traditional strapdown Kalman filter method is appropriately improved,and the FIR filter,the Kalman filter without parameters,the Kalman filter with vertical specific force factor error,and the Kalman filter with horizontal attitude error and vertical specific force factor error are compared and analyzed,The results show that the Kalman filter with only the vertical specific force factor error is the best.3.Aiming at the problem of gravity anomaly accuracy under the fluctuating flight condition with UAV as the carrier,four groups of fluctuating flight data with UAV as the platform are used to illustrate their impact on the accuracy.The results show that the increase of the fluctuating flight degree of UAV will lead to the deterioration of gravity measurement accuracy;The error parameter and compensation method are adopted,and the estimation and compensation process are improved;The experiment shows that the internal coincidence accuracy of the first three groups under large fluctuation conditions has been improved by 0.10 mgal,0.42 mgal and 0.25 mgal respectively.With the weakening of UAV fluctuation degree,the compensation effect has been reduced accordingly.When the fluctuation flight degree is small,the coincidence accuracy has been reduced by 0.07 mgal.Therefore,the practicability of this method under the condition of large fluctuation flight maneuverability is obtained.