International Society for Industrial Process Tomography

Simultaneous and Continuous Excitation Strategy for
High-speed EIT: the ONE-SHOT method

A. Dupré^1*, S. Mylvaganam²

¹No current affiliation

²Department of Electrical Engineering, IT and Cybernetics, Faculty of Technology, Natural Sciences

and Maritime Sciences, University College of Southeast Norway, 3901 Porsgrunn, Norway;

^*Email: Antoine.dupre@alumni.epfl.ch

ABSTRACT

This article describes a novel concept for soft-field tomography, building upon the Multiple-excitation multiple-receiving capacitance tomography technique and the fully simultaneous excitation principle. The method is called ONE-SHOT, for ONe Excitation for Simultaneous High-speed Operation Tomography. Using “off-the-shelf-modules” a dedicated hardware is designed allowing for simultaneous excitation of all electrodes with linear superposition of multiple sinusoidal waves at different AC frequencies and simultaneously monitoring the current in the sensing resistors. Digital demodulation of sampled signals is proposed to extract the frequency components of interest in the system response. As compared to the sequential excitation technique, an increased number of samples is available for digital demodulation leading to considerable reduction in the effects of white noise in the system response. The real breakthrough in the proposed hardware design, sensing and signal processing methods, is the simultaneous excitation of all electrodes at once, thereby avoiding multiplexing with improved suppression of transients in high-speed operation. The ONE-SHOT protocol consists of single excitation pattern that can be set continuously, thereby eliminating problems due to contact impedance and transients in many high-speed EIT applications. This article will cover the description of hardware design for implementing the ONE-SHOT method, a discussion about the selection of the set of AC frequencies for excitation, the sensing methodology, a proof-of-principle experiment, and SPICE circuit simulation results complementing the illustration of the method.

Keywords Contact Impedance, ONE-SHOT Method, Simultaneous and Continuous Excitation, Transients

Industrial Application General