A compact electrical capacitance tomography system

Most existing electrical capacitance tomography (ECT) systems are designed using a 19" Eurocase and they are relatively expensive. To reduce the size and cost, a compact ECT system has been developed. It is based on a charge/discharge capacitance measuring circuit and a USB data acquisition (DAQ) unit from NI. It has 6 measurement channels and is housed in a box measuring 158times80times96 mm. The system hardware is operated by a laptop via a USB port. The software is written in LabVIEW and the image reconstruction software in MATLAB. This paper presents the hardware design for the compact ECT system, the calibration procedure, and the image reconstruction from capacitance measurements. The performance of the system has been evaluated and the measurement results are presented. It is concluded that the compact ECT system is capable of providing small capacitance measurements and generating tomograms. The signal-to-noise ratio (SNR) of the measurement system is acceptable and can be improved further.