Research And Application Of Attitude Transformation In The Airborne Magnetic Gradient Measurement

Due to advances in technology, aeromagnetic survey developed from the previous single parameter measurement to the current multi-parameter measurement, gradient measurements can also be implemented at the same time of the component(?T) measurement. The aircraft is used as the carrier in the aerial magnetic survey, the attitude of the aircraft(yaw, pitch and roll) plays an important role in the quality of the measured data. So it is necessary to analyze magnetic field and its gradient influenced by the attitude changes of the aircraft.The aircraft can’t always fly at the same altitude when airborne magnetic survey was carried out. While the computing was often based on the data was acquired at the flat surface, so the transformation magnetic field data observed at curved surface into flat surface is particularly important. In the period of multi-parameter measurement, study on how to effectively complete this transformation using multi-parameter data of actual measurement become very necessary.On the basis of previous studies, attitude correction method was studied, rigorous derivation of the transformation matrix for aeromagnetic survey was carried out, and the contact between the transformation matrix and the strap-down matrix in inertial navigation was established. At the same time, the gradient of the corresponding attitude was obtained by the difference method, and the influence of the attitude change to the gradient is studied. When the attitude angles change in a small range, quantitative analysis of the impact of the gradient of the corresponding direction was given, the results have a certain guiding significance for the actual measurement.In addition, recovery of the gradient from the difference method by using the transformation matrix obtained the data that consistent with the theoretical value, which proved the correctness of the transformation matrix and the validity of the calculation. error analysis was launched by Taylor expansion of the transformation matrix. According to the need in the actual measurement(magnetic three component Tx,Ty,Tz or magnetic gradient three component (?)),accuracy requirements for the attitude angle was obtained.Through careful analysis, it was pointed out that there is no simple correspondence between the tangential gradient and the horizontal gradient of the magnetic field on the curved surface, the same to the normal gradient and the vertical gradient. Through the basic formula of potential field, a method was obtained from the boundary element method of transforming magnetic field data observed at curved surface into flat surface using ?T and the normal gradient derived from measured gradient. The principle of this method was clear, simple and practical.