频率域航空电磁系统线圈姿态变化影响及校正方法

Coil Attitude Influence and Attitude Correction Method for Frequency Domain Airborne Electromagnetic System

频率域航空电磁系统线圈姿态变化影响及校正是一项探索性很强的开拓性工作,目前国内尚无成熟经验可循.吊舱式直升机频率域航空电磁法线圈安装在吊舱内,探头姿态变化相对较大,因此姿态校正提高了其数据处理精度,对提高航空电磁法数据处理水平具有重要意义.为了消除吊舱式直升机频率域航空电磁系统因收发线圈姿态发生变化,而导致的电磁探头接收地下地质体电磁响应数据产生的误差,采用三维频率域有限差分方法模拟计算频率域航空电磁系统的电磁响应,分析了不同频率、不同收发线圈姿态变化类型对水平共面(HCP,全称horizontal co-plane)和垂直同轴(VCX,全称vertical coaxial)线圈装置的电磁响应影响.计算结果表明:垂直同轴线圈装置因姿态角度变化引起的测量误差比值远大于水平共面装置,而且频率越高,受探头姿态角度变化的影响越大.垂直同轴装置主要受俯冲姿态变化的影响,水平共面装置受摇摆和俯冲这2种姿态变化的影响.在此基础上,根据姿态误差几何校正方法进行了电磁数据校正,有效地去除了因线圈姿态变化造成的误差响应.

Coils attitude influence and attitude corrections method for frequency domain airborne electromagnetic system are pio- neering jobs in frontiers without much experience. The coils of towed helicopter frequency airborne electromagnetic method are mounted in a bird, coils attitude changes a lot relatively, so attitude corrections improve the precision of data processing. It is important to impove data processing level for airborne electromagnetic method. Attitude variations of helicopter bird frequency electromagnetic system transmitting and receiving coils, result in electromagnetic data error which is produced by underground geologic body and received by the electromagnetic sensor. Analog computation is used in this study to work out the frequency domain airborne electromagnetic response by 3D frequency domain finite difference method. The response of horizontal co-plane and vertical coaxial systems from different frequencies and different types of sensor rotation is analyzed. The results show that the measurement error from vertical coaxial system is greater than that of horizontal co-plane system. The measurement error caused by the change of rotation angles is more remarkable than higher frequencies. The vertical coaxial system is mainly affect- ed by pitch rotation, whereas the horizontal co-plane system is mainly affected by roll and pitch rotation, and the latter has great influence in the same rotation angle. On the basis wipes out response error from attitude changing of coils.