| The aeromagnetic measurement system based on the helicopter platform has the advantages of strong load capacity,high work efficiency,and wide measurement range,and has broad application prospects in the fields of geological prospecting,magnetic target detection and geomagnetic navigation.When carrying out aeromagnetic measurement,it will be affected by various magnetic interferences,mainly including the magnetic interference generated by the fixed magnetic field,induced magnetic field and eddy current magnetic field in the carrier,as well as the magnetic interference formed by the operation of airborne electrical equipment.In order to improve the accuracy of the aerial measurement of the total geomagnetic field and the geomagnetic component,this paper studies and designs the corresponding compensation algorithm.Aiming at the total geomagnetic field,based on the T-L model,a scalar aeromagnetic compensation algorithm based on total amount constraints is designed.In order to reduce the blindness of filter frequency band selection,a method for determining aeromagnetic interference frequency band based on Weltch power spectrum analysis is studied.Through the power spectrum analysis of the column vector in the parameter solution matrix,the optimal filter frequency band required for the solution of the compensation coefficient is estimated effectively.Aiming at the geomagnetic vector,based on the T-L model,a vector aeromagnetic compensation algorithm based on component constraints is designed.The influence of eddy current magnetic interference on geomagnetic vector measurement is analyzed,and a vector compensation model including eddy current magnetic interference is researched and established.The actual measurement results show that considering the eddy current magnetic interference can significantly improve the compensation effect of the geomagnetic vector.It is difficult to compensate the alternating magnetic interference generated by electromechanical equipment by calculating the compensation coefficient in the T-L model.This paper studies the adaptive coherent noise suppression algorithm.A fluxgate sensor is installed at the near fuselage and the far fuselage,respectively,as the reference sensor and the target sensor,and the interference magnetic field transfer function between the two sensors is established to suppress the coherent noise,the three components of geomagnetism are further compensated.In order to verify the actual compensation effects of the above three algorithms,this paper designs and establishes an aeromagnetic measurement system based on a helicopter platform,and conducts an field verification test.The results show that after compensation,the root mean square error of the total field measurement of the airborne optical pump is reduced from1.43 n T to 0.3n T,and the root mean square error of the three components of the airborne fluxgate is reduced from 486.89 n T,342.97 n T and 674.31 n T,respectively to 28.61 n T,33.35 n T and 19.74 n T,good compensation effects have been achieved for the total amount and component of geomagnetism. |
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