Research On Coefficient Solution Method Of High Precision Aeromagnetic Compensation

Aeromagnetic prospecting technology is widely used in geological survey,geomagnetic navigation and many other fields because of its advantages of high detection efficiency and wide detection range.With the continuous improvement of the accuracy of the current detection equipment,as a necessary step in the process of aeromagnetic exploration,aeromagnetic compensation technology has received extensive attention in related fields.At present,in the application of aeromagnetic compensation,the three-component data collected by three-axis fluxgate magnetometer and the total field data collected by optical pump magnetometer are mainly used.Based on the aircraft magnetic interference model,the multivariate linear equations are established,and the corresponding compensation coefficients are calculated.Then the interference generated by the aircraft is estimated by the coefficient,and the data detected can be compensated.Therefore,how to find the optimal compensation coefficient becomes the key to improve the accuracy of aeromagnetic compensation.However,in the process of calculating the coefficients,some problems have been found,such as the non-uniformity of the geomagnetic field,the uncertainty of the aircraft maneuvering quality and the ill-condition of the aircraft magnetic interference model.These problems will affect the solution of coefficients.Based on the above problems,the main work of this paper includes:Firstly,in view of the inconsistency between the hypothesis and the actual geomagnetic field,the composition of the geomagnetic field is studied,and the influence of the geomagnetic variation coupled to the mobile data after filtering on the coefficient solution is analyzed.By deriving the Legendre polynomial function of the local geomagnetic model,the geomagnetic gradient is modeled,and a data preprocessing method based on geomagnetic inhomogeneity is proposed to improve the compensation accuracy.Secondly,aiming at the problem that the maneuvering quality can not be guaranteed in the actual detection flight process,a cross grouping coefficient solution method based on the maneuvering quality evaluation is proposed.This method recombines all the maneuvering characteristics of different maneuvering cycles in the form of cross grouping,and selects the optimal maneuvering combination based on the evaluation of maneuvering quality,and then solves the corresponding compensation coefficient.Experiments show that this method overcomes the problem of large amount of calculation of the original cross-grouping,and the aeromagnetic compensation coefficient calculated has strong adaptability.Finally,aiming at the problem of low precision of solving the coefficients caused by the ill-conditioned model,combined with the reality of aeromagnetic compensation,an improved adaptive genetic algorithm is proposed to solve the aeromagnetic compensation coefficients.The aeromagnetic compensation coefficients are solved under different objective functions.The method is used to solve and analyze the optimal compensation results of a single group of coefficients,which provides a new way to improve the aeromagnetic compensation coefficients.