The development of digitally controlled metal detection techniques for the industrial environment

Dyer, Christopher 2024. The development of digitally controlled metal detection techniques for the industrial environment. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Pulse induction metal detection is a technique for identifying metal within a pulsed magnetic field. Analogue methods traditionally measure induced voltage across coils, with the presence of metal determined by comparing voltage levels. In noisy industrial environments false detections occur, necessitating increased threshold levels which can decrease sensitivity. Industrial pulse induction metal detectors are mounted on conveyor frames to detect tramp metal in products and to protect downstream equipment. Industrial environments are challenging for the metal detector as noise from various sources, including electrical motors and magnetic products such as haematite and magnetite, pose challenges and can lead to false detections. This thesis determines the possibility and methodology of increasing the sensitivity of a pulse induction metal detector, without increasing the strength of the magnetic field or changing the coil design of the analogue method. It is found that by digitising the control methodology, an algorithm can be implemented that can increase the performance of the metal detector. This algorithm adds a temporal element to the decision mechanism resulting in better immunity against noise and a lower threshold requirement for the presence of metal. The algorithm results in sustained performance, allowing for conveyor belt speeds to increase up to 200% more than is possible with the traditional analogue method. This thesis presents the research and development of a digitised pulse induction metal detector, that showcases superior performance compared to industrial analogue methods.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Engineering
Uncontrolled Keywords:	1) Metal Detection 2) Pulse Induction Metal Detection 3) Magnetic Polarizability Tensor 4) Digitization 5) Digital Signal Processing 6) Mining
Additional Information:	Thesis temporarily restricted while length of embargo is under discussion.
Date of First Compliant Deposit:	27 January 2025
Last Modified:	27 Jan 2025 09:29
URI:	https://orca.cardiff.ac.uk/id/eprint/175567

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