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This paper reports vehicle based electromagnetic induction (EMI) array sensor data inversion and discrimination results. Recent field
studies show that EMI arrays, such as the Minelab Single Transmitter Multiple Receiver (STMR), and the Geophex GEM-5 EMI
array, provide a fast and safe way to detect subsurface metallic targets such as landmines, unexploded ordnance (UXO) and buried
explosives. The array sensors are flexible and easily adaptable for a variety of ground vehicles and mobile platforms, which makes
them very attractive for safe and cost effective detection operations in many applications, including but not limited to explosive
ordnance disposal and humanitarian UXO and demining missions. Most state-of-the-art EMI arrays measure the vertical or full vector
field, or gradient tensor fields and utilize them for real-time threat detection based on threshold analysis. Real field practice shows that
the threshold-level detection has high false alarms. One way to reduce these false alarms is to use EMI numerical techniques that are
capable of inverting EMI array data in real time. In this work a physically complete model, known as the normalized volume/surface
magnetic sources (NV/SMS) model is adapted to the vehicle-based EMI array, such as STMR and GEM-5, data. The NV/SMS model
can be considered as a generalized volume or surface dipole model, which in a special limited case coincides with an infinitesimal
dipole model approach. According to the NV/SMS model, an object's response to a sensor's primary field is modeled mathematically
by a set of equivalent magnetic dipoles, distributed inside the object (i.e. NVMS) or over a surface surrounding the object (i.e.
NSMS). The scattered magnetic field of the NSMS is identical to that produced by a set of interacting magnetic dipoles. The
amplitudes of the magnetic dipoles are normalized to the primary magnetic field, relating induced magnetic dipole polarizability and
the primary magnetic field. The magnitudes of the NSMS are determined directly by minimizing the difference between measured and
modeled data for any known object and any type of EMI sensor data. The EMI array data are inverted via the combined NV/SMS and
differential evolution inversion method that uses a search scheme to estimate the location of the target. First, the applicability of the
NV/SMS and DE algorithms to STMR and GEM-5 data sets is demonstrated by comparing the modeled data against the actual data,
and finally the discrimination studies are conducted using as discrimination parameters the total NV/SMS and the principal axis of the induced magnetic polarizability tensor for each target.
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