Design Proposal of a Metal Detector for Humanitarian Demining

Abstract

Abstract-In this research work, a novel design of a metal detector is proposed. To fulfill this, several results obtained with an edge based FEM simulator, and an analytical model were used.The main objective of the proposed detector is to diminish the influence of the soil in the detector performance, given that this is an important problem on landmine detection [1]. By using numerical modeling could be demonstrated the feasibility of the proposed design. Keywords: Demining,Electromagnetic fields, Humanitarian demining, Landmines, Metal detectors, Numerical modeling.I. INTRODUCTION According to [2] a receiver coil will get the field induced directly by the transmitter coil, the field induced by the soil and the field induced by buried objects. Usually, a metal detector senses the sum of those induced fields and it should discern the presence of a metal from the mix of fields [2].The field induced directly by the transmitter coil on the receiver coil could be excluded from the measure; given that, it generates a constant voltage. Commonly, this voltage is measured during the detector construction, and it is defined as a threshold or zero reference level, it could require periodic calibration and it could show important problems when the battery is discharging.By other side, it is necessary to recognize the signal produced by soil, the soil itself induces a voltage in the receiver coil that could be construed as the presence of a metal. Usually it is necessary to do some calibration procedures with commercial detectors, before the detection process is made; however, soil can show variable electromagnetic properties and the detector would work decalibrated.II. METHODSThe influence of soils in metal detector performance has been studied previously. Theoretically, by using analytical models in [2] ,[3] y [4], by using a numerical modeling. These studies, allow to conclude that the electromagnetic properties of soils are highly influent in the detector performance, especially when soils have relative magnetic permeability different from 1. It was experimentally confirmed in [1], these results show that a detector can decrease its probability of detection and increase its false alarms rate, when the soil is magnetic. Taking into consideration that a detector needs a strategy to diminish the effect of soil in its performance.In order to calculate the induced field of a buried metal a finite elements simulator was developed. In this simulator the model presented in [6] was implemented using the Matlab software This design proposal aims to vanish the voltage induced directly by the transmitter coil, and the voltage induced by soil, in order to avoid a pair of calibrations.To fulfill this, it is needed to analyze the induced magnetic fields behavior in the scenario of Fig.1, a horizontal coil over a half space.

Antipersonnel landmines in the Colombian internal conflict: implications for technology development

“…Both private and state-owned companies and universities (in Colombia and Europe) interested in generating knowledge for humanitarian demining, and with the support of Colciencias, have developed research projects to create tools for humanitarian demining [26]. Universities in Colombia such as Los Andes, Antioquia, Javeriana, and Nacional have carried out research projects to detect improvised explosive devices based on metal detectors and simulators [27], monostatic and polarimetric ground penetration radar [30], artificial vision systems [28], and nuclear quadrupole resonance [29].…”

Characterization and reduction of background noise for the detection of plastic anti-personnel landmine in mineralized soil

“…Although some reports have confirmed this soil effect [22][23][24][25] and performed a simple theoretical analysis of the soil response [26][27][28][29], few have detailed a quantitative analysis of the background noise under the different electromagnetic properties on the mineralized soil. Conventionally, the differential pick-up coil is used to suppress the soil effect [30][31][32]. As current manufacturing techniques cannot ensure that the electrical and geometrical parameters of the two coils are identical, a sensor still outputs an obvious background noise in strongly mineralized regions (containing for example bauxite, laterite, magnetite or magmatite).…”