便携式瞬变电磁系统多目标响应反演研究

The near-surface unexploded ordnance poses a great threat to people's life and property. The portable transient electromagnetic system has a great ability of anti-interference and can adapt to all kinds of complex terrain, which has become a hotspot in unexploded ordnance detection. In this study, the mixing matrix is used to study the multi-objective response of portable transient electromagnetic system. By studying the response characteristics under different system, the influence law of sensor structure and system detection mode is revealed, and the mixing matrix of multi-objective response of portable system is constructed according to this law. In order to estimate the number of targets efficiently, the extending theory and method of mixed matrix are studied, and the intrinsic relation between the eigenvalues and the number of targets of the extended mixed matrix is revealed. The singular value decomposition of the extended mixing matrix is used to estimate the target by the number of nonzero eigenvalues. In this way, the estimation efficiency is greatly improved. In order to estimate the target parameters accurately, the mixing matrix is normalized by Schmitt's orthogonalization. On this basis, the orthogonal operation is used to suppress the response noise, and estimate the magnetic polarization tensor of the target accurately. The differential evolution algorithm is used to estimate the target position and improves the accuracy. Through the research above, we can achieve efficient and accurate inversion of multi-target response of portable transient electromagnetic system.

近地面未爆弹对人们生命财产构成极大威胁，便携式瞬变电磁系统抗干扰能力强，能够适应各种复杂地形，成为未爆弹探测的研究热点。针对传统的循环反演算法在目标数量较大时，反演速度慢、精度低的问题，本课题以混合矩阵为研究对象，开展便携式瞬变电磁系统多目标响应的反演研究。通过研究不同系统激励下目标响应特性，揭示传感器结构与系统探测方式对响应的影响规律，根据此规律构建便携式系统多目标响应的混合矩阵。为高效估计目标数量，研究混合矩阵的扩展理论与方法，揭示扩展混合矩阵的特征值与目标数量之间的内在联系，通过对扩展混合矩阵进行奇异值分解，以非零特征值的数量估计目标数量，提高估计效率。为准确估计目标参数，通过施密特正交化实现混合矩阵的规范化。在此基础上，利用正交运算抑制响应噪声，准确估计目标体磁极化张量，利用差分进化算法估计目标位置，提高估计精度。通过以上研究最终实现便携式瞬变电磁系统多目标响应的高效、准确反演。

近地面未爆弹对人们的生命财产构成极大威胁，便携式瞬变电磁系统抗干扰能力强，能够适应各种复杂地形，被广泛用于未爆弹探测。针对传统反演算法在分离多目标重叠响应时反演速度慢、精度低的问题，本课题以多目标重叠响应为研究对象，开展基于便携式瞬变电磁系统的多目标响应反演研究。通过研究便携式系统传感器结构与系统探测方式，实现了高性能便携式系统传感器设计与多目标响应建模，实验结果表面系统能够准确探测1.2m深的目标体。基于偶极子模型，研究利用优化的长直螺线管产生均匀性达到99%的一次场来标定各个典型未爆弹纵轴电磁特性，作为反演算法估计结果准确性的依据。借助电磁特性完成目标分类，实验结果表明根据电磁特性能够准确分离未爆弹与各种无害目标。研究阵列系统的联合对角化理论与方法，对便携式系统探测下多目标响应进行重组变换获得等效的联合矩阵，利用奇异值分解方法获得目标的电磁特性。理论研究表明奇异值分解后对角矩阵中非零元素个数正好为目标个数的3倍，根据这一规律实现目标数量的准确估计。研究利用斯密特正交化方法为每个目标体配置最佳磁极化张量，利用位置再排算法加速多目标响应反演的收敛速度，理论与试验结果均表明通过斯密特正交化与位置再排算法，能够将反演精度提高近10倍，反演速度加速到与单个目标反演速度相当。本课题提出的算法能够快速、准确的实现便携式系统激励下多目标重叠响应的反演，为多目标混叠信号的处理提供借鉴，同时极大地提高了便携式系统探测未爆弹能力。