Detection of low-metallic content landmines based on electromegnetic induction model.

doctoral thesis

• Title (croatian): Otkrivanje mina s malom količinom metala zasnovano na elektromagnetskom induktivnom modelu.
• Author: Davorin Ambruš
• Mentor: Vedran Bilas (mentor)
• Committee member: Vedran Bilas (član povjerenstva)
• Granter: University of Zagreb; Faculty of Electrical Engineering and Computing; (Department of Electronic Systems and Information Processing); Zagreb
• Defense date and country: 2019, Croatia
• Scientific / art field, discipline and subdiscipline: TECHNICAL SCIENCES; Electrical Engineering; Electronics
• Universal decimal classification (UDC): 621.3 - Electrical engineering

Abstract

This thesis presents an attempt to improve the existing methods of close-in detection of landmines using electromagnetic induction (EMI) sensing. In the introductory part, an analytical forward model of a scanning EMI sensor for metallic target characterization based on the induced magnetic dipole model is derived from the governing EMI equations. Three different static inversion methods for the estimation of induced dipole model parameters from EMI and sensor positional data are analyzed; the method based on nonlinear least squares (NLS) approach, the quasi-numerical HAP method featuring the modified NSMS model, and the metaheuristic method. Inversion performance of each method is evaluated on a synthetic data set, for selected metallic targets and representative search head geometries. A novel approach to search head's pose tracking based on the measurement of its own primary magnetic field and the application of the extended Kalman filter is presented. Following a similar methodology, a new concept of dynamic dipole inversion that avoids the need for sensor positional data is proposed. The effects of background interferences on a response of an EMI sensor and the methods for their compensation are also analyzed. A novel concept for robust estimation of target's shape, based on temporal information stored in the eigenvalues of the estimated magnetic polarizability tensor, is introduced. Finally, all of the analyzed modeling, inversion, tracking and compensation approaches are experimentally validated on several sensing platforms in a laboratory and field environment.

Abstract (croatian)

Ovaj doktorski rad rezultat je istraživanja kojima je cilj unaprjeđenje postojećih metoda za blisko otkrivanje mina uporabom elektromagnetskih induktivnih (EMI) senzora. U uvodnom dijelu rada prezentiran je analitički model skenirajućeg EMI senzora, izveden iz klasičnih jednadžbi elektromagnetskih potencijala u njihovom magnetskom kvazistatičkom obliku primjenom dipolne aproksimacije. Analizirane su tri različite statičke inverzne metode za estimaciju parametara dipolnog modela; nelinearna metoda najmanjih kvadrata, kvazinumerička HAP metoda s modificiranim plošnim magnetskim izvorima, te metaheuristička metoda. Provjera i usporedba performansi navedenih inverznih metoda provedena je na sintetičkom uzorku podataka za odabrane metalne mete i reprezentativne geometrije senzorskih glava. Razvijena je nova metoda praćenja položaja i orijentacije senzorske glave zasnovana na mjerenju primarnog magnetskog polja samog detektora i primjeni proširenog Kalmanovog filtra (EKF). Slijedeći sličnu EKF metodologiju, predložen je novi koncept dinamičke dipolne inverzije kojom se izbjegava potreba za sustavom praćenja senzorske glave. U radu su također analizirani i učinci pozadinskih smetnji na odziv EMI senzora, te metode njihove kompenzacije. Obrađen je i novi koncept robusne estimacije oblika metalnog predmeta zasnovan na informacijama sadržanima u svojstvenim vrijednostima estimiranog tenzora magnetske polarizabilnosti u vremenskoj domeni. Sve navedene metode i pristupi modeliranju senzora, dipolnoj inverziji, praćenju položaja senzorske glave, te kompenzaciji pozadinskih smetnji eksperimentalno su provjereni na nekoliko različitih senzorskih platformi u laboratorijskim i terenskim uvjetima.

• Keywords: metal detection; metal characterization; electromagnetic induction; induced magnetic dipole; magnetic polarizability tensor; nonlinear least squares; magnetic tracking
• Keywords (croatian): detekcija metala; karakterizacija metala; elektromagnetska indukcija; inducirani magnetski dipol; tenzor magnetske polarizabilnosti; nelinearna metoda najmanjih kvadrata; magnetsko praćenje; HAP metoda; diferencijalna evolucija; prošireni Kalmanov filtar
• Language: english
• URN:NBN: urn:nbn:hr:168:453778
• Study programme: Title: Electrical Engineering and Computing; Study programme type: university; Study level: postgraduate; Academic / professional title: Doktor znanosti elektrotehnike i računarstva (Doktor znanosti elektrotehnike i računarstva)
• Type of resource: Text
• Extent: 305 str. ; 30 cm
• File origin: Born digital
• Access conditions: Closed access
• Created on: 2019-06-03 09:15:53