Magneto-Inductive Magnetic Gradient Tensor System for Detection of Ferromagnetic Objects

Abstract

A miniature magnetic gradient tensor system may be used in small spacecraft for mineral prospecting and detection of unexploded explosive ordnance. The system consists of a magneto-inductive (MI) sensors array, a signal extraction circuit, and a microcontroller. A magnetic gradient full-tensor configuration utilizes four MI sensors arranged in a planar cross structure and is employed to minimize orientation and orthogonality errors. The system's performance was checked by data validation and magnetic anomaly detection. Numerous experimental results demonstrate that the system is able to detect a low-amplitude magnetic field as low as 8.28 nT at 10 Hz, with a typical noise floor of 0.235 nT/Hz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{1/2}$</tex-math></inline-formula> at 1 Hz. The system can identify nearby ferromagnetic objects clearly, which indicates its feasibility for weak magnetic anomaly detection.