Electromagnetic tracking methods and magnetic modelling for distortion compensation

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Cavaliere, Marco
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University College Cork
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The thesis presents a comprehensive study of electromagnetic tracking (EMT), focusing on developing methods and techniques to reduce and compensate for distortions in the magnetic field through improved modelling and real-time correction methods. To this end, the research-oriented Anser EMT system is employed. Anser is the Latin name of the greylag goose, which uses the geomagnetic field for navigation. In this work, a general method for modelling magnetic fields is developed to significantly improve the Anser EMT magnetic model by correcting systematic errors and including magnetic shielding. Moreover, real-time compensation techniques for dynamic distortion are proposed using external reference sensors. Further improvements are demonstrated for dynamic tracking by optimising the EMT model and algorithm. Finally, the effectiveness of the Anser EMT system for developing novel EMT applications is demonstrated by introducing alternative tracking techniques based on the magnetic scalar potential formulation, particularly suited for tracking the elongated sensor coils used in medical applications, and on the magnetic vector potential formulation, for tracking large-area PCB coils. Overall, this work provides the theoretical and experimental basis for a new approach to distortion rejection in EMT systems with significant potential for future clinical benefit in the years to come.
Electromagnetic tracking , EMT , Image-guided navigation , Minimally-invasive surgery , Magnetic model , Distortion , Object tracking , Kalman filter , Non-linear optimisation
Cavaliere, M. 2023. Electromagnetic tracking methods and magnetic modelling for distortion compensation. PhD Thesis, University College Cork.