Research On An New Type Electrical Resistance Tomography Sensor

Electrical Resistance Tomography (ERT in short)is an new kind of process tomography technology,which use APT to test the response voltages around the boundary of the sensitive field created by certain excitation current signal, and then reconstruct the image of the tested object based on the acquired data, through certain algorithm.This technology is now widely used in the fields of PT (Process Tomography) and MT (Medical Tomography) because it’s a low cost, real-time and portable imaging technique. However its reconstruction quality still needs to be improved. Many articles in this area have pointed out that we can improve the reconstruction quality by increasing the independent measurements.In order to increase the independent measurements, we replace the16-electrode APT which is now widely used in ERT-system with a new48-electrode APT. In this way, we increase the independent measurements by3times. Many articles also reported that:the increase of electrode-number will resulted in deterioration of current density uniformity in the sensitive field. This effect will decrease the quality of reconstructed image. In order to solve this problem, we proposed a new mode of excitation—group neighbor excitation (GNE in short). We simulated this mode of excitation in an kind of FEM analysis software--COMSOL Multiphysics3.4, and the simulation result proved that under this mode,48-electrode APT has an similar distribution of current density as16-electrode under neighbor-excitation mode.In order to reconstruct image base on the data acquired by48-electrode APT, we developed a new reconstruction based on LBP, and realize it in Matlab. We use this program to reconstruct image based on a set of data acquired by48-electrode APT from COMSOL Multiphysics3.4simulation, and compare it with that of16-electrode APT. The reconstruction result showed that data acquired by this new kind of APT can reconstructed much better image than16-electrode APT.Finally, in order to realize the GNE of48-electrode APT in the existing platform of16channels ERT system, we designed a Goup-selection circuit based on DG411, and used it to carry out experimental measure. Experiment result showed that:This circuit can preform well, and can attach different groups of electrodes in the48-electrode APT to the channels of ERT system in proper order, under the command of control signal. This circuit offers a hardware realization for GNE, strengthens its physical background and makes it much more practical.