Research On Digitalization Of Electrical Capacitance Tomography System

Based on the capacitance sensing principle, Electrical Capacitance Tomography (ECT)with advantages of non-intrusion, fast response and low cost is one of the branch of Progress Tomography.The latest reports manifest this technique has a widespread application for the detection and control of industrial process, which is a very potential PT technique. The Electrical Capacitance Tomography system widely adopts analogue filter and demodulation, which is limited in the speed and precision of the tomography due to the performance of the analogue device. The author proposes a scheme on the digitalization of Electrical Capacitance Tomography system. The main research work and achievements are presented as follows:1. The digital hardware system of Electrical Capacitance Tomography technology is designed and achieved on the basis of the former system including the exciting module, the measurement module and data acquisition module.2. It uses DSP (TMS320C6701) to control the hardware system and accomplish digital filter and frequency analysis to the voltage signal of electrode which is sampled by A/D.3. It realizes the communication between DSP and PC based on PCI bus and develops the real-time imaging software package, including control software and reconstruction software.4. A series of performance experiments have been done on the new-developed ECT system, including static performance experiments and dynamic performance experiments.a) The static performance experiments include the experiments on different objects and typical static models of gas/liquid two-phase flow.The results showed that the obtained reconstructed images were quite clear.b) The dynamic performance test is mainly about the speed of the reconstruction images. The result of speed test is about 15 frames per second.