Investigation Of Electrical Resistance Tomography Based On The Single Drive Electrode Method

The precise measurement of two-phase/ multi-phase flows which exist widely in thenatural and industrial processes has been an issue demanding the solution but stillnot solved with satisfaction. Electrical Resistance Tomography (ERT) as a branch ofthe process tomography technique is a simplified form of EIT technology. As anon-line measurement technique possessing advantages of visualization, non-invasion,low cost and non-radiation, ERT has developed into the new generation of processparameter measurement technique.With the development of electron and industry technique, the requirements of DataAcquisition System (DAS) in industrial field are becoming higher and higher andthe exisiting ERT system can not reach that. Therefore, in order to improve the ERTsystem performance, launching on the fundamental research of ERT system, themain work and research results are as follows:1. A new current-exciting and current-measuring Data Acquisition Method (DAM),namely the single drive electrode method, and its mathematic model arepresented based on the summarization and analysis of the DAM adopted by ERTsystem. And the analytic solutions of ERT forward problem under two differentmedia distributions have been worked out.2. The simulation model of the ERT system based on the single drive electrodemethod has been set up using ANSYS software. The simulation study of thesingle drive electrode method is carried out from the aspects of the distributionof the sensing field and data analysis. The validity of the single drive electrodemethod is verified, the similarities and differences between the single driveelectrode method and the adjacent method are discussed and the influence of thecontact resistance on the sensing field is presented. Based on the above analysisa new DAS was put forward.3. A new ERT data acquisition platform based on the single drive electrode methodhas been built. For simplifying the hardware structure and improving thereal-time performance of ERT system, the bi-directional pulse current withadjustable amplitude is adopted as the exciting signal in the new system. A newsignal generator that can output three kinds of waveforms has been designed.And two PCB-boards named PC-7429 and PC-7501 were used in the DAS as thedata acquisition module and the control module respectively. The experimentsusing the new system have been finished in the laboratory, the reliability of thesystem has been verified by the analysis of the acquired data, and the feasibilityof the single drive electrode method in actual application has been furthervalidated.4. Based on the qualitative back projection algorithm and the qualitative sensitivityalgorithm, the reconstruction algorithm of the single drive electrode method hasbeen studied, the reconstruction images of the new ERT system using themodified sensitivity algorithm were presented, and a new back projectionalgorithm based on the electric lines of force has been brought forward with theacademic expressions.