Electrical Resistance Tomography System with Zooming Mechanism

J. Frounchi and H. Soltani

Microelectronic and Microsensor Research Laboratory, Faculty of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran, Email: jfrounchi@tabrizu.ac.ir

ABSTRACT

A 2-D resistivity imaging system has been designed and implemented which uses an array of sixteen electrodes inserted in the surface to obtain two-dimensional electrical resistance distribution under the Earth's surface. From this array, four electrodes, two for current injection and the others for potential measurement, are selected via a switching network by an I/O card controlled through the LABVEW software and the data is collected by a host computer. The finite-difference approximation is chosen to discretize Poisson’s equation and the reconstruction algorithm has been implemented in the MATLAB. Several objects were buried in a big plastic container of soil in our laboratory and the surface potential was measured at several points using the different array configuration. The reconstructed images from these objects clearly reveal the relative shape and size of these objects. The results showed that the realized system is not sensitive to noise since for both high and low damping factors, the quality of reconstructed images is acceptable. Our results are compared to those obtained from the RES2DINV program which is a standard 2-D resistivity inversion program. Using the FDM technique, we have been able to zoom in a specific region by changing the grid spacing and number in that region. Consequently, this system can be employed to identify complex buried resistivity structures.

Keywords Electrical resistance tomography, Zooming mechanism, Finite-difference method.