Research On Sensitive Field Establishment And Imaging Data Redundancy Of Planar Array Electrode Detection System

The planar array electrode sensing technology is an emerging non-destructive testing technology developed based on the electrical capacitance tomography(ECT)technology.The planar array electrode detection technology has the advantages of the ECT technology,and it also has deficiencies.The planar array electrode sensor utilizes the edge effect of the capacitor to achieve detection.Because the fringing electric field is very weak,the capacitance data is susceptible to noise,resulting in poor stability of the image reconstruction process.At the same time,the image reconstruction quality of the same-plane array electrode detection system is closely related to the quality of the sensitive field matrix.For this reason,this paper focuses on the 3×4 coplanar array electrode sensors and investigates the capacitive data and the sensitive field.For this reason,for the 3×4 coplanar array electrode sensor,the capacitance data and the sensitive field are studied.(1)First,the theoretical basis of ECT technology is summarized and analyzed.For the planar array electrode sensor,the sensor's sensitive field matrix is studied by singular value decomposition(SVD).Finally,the optimal form of the sensitivity field matrix is obtained,which improves the image reconstruction quality.(2)Secondly,because the capacitive data of the planar array electrode capacitive sensor is susceptible to environmental noise,it causes the problem of poor stability of the image reconstruction process.For the capacitance data of the planar array electrode sensor,a redundancy analysis method is proposed.This method analyzes the contribution rate and the anti-jamming ability of the capacitance data to image reconstruction from different electrodes.After the redundant capacitance data is removed after redundancy analysis,the remaining data is used for image reconstruction.The stability of the image reconstruction process has been significantly improved while the quality of the reconstructed image has not been reduced.(3)Finally,for the aerospace composite materials with anisotropy,porosity,low thermal conductivity,low electrical conductivity and strong acoustic absorptioncharacteristics,a coplanar array electrode imaging detection system platform was built,and its feasibility was experimentally verified.The results show that the system is feasible to detect defects in the adhesive layer of composites for aviation,and the minimum detectable diameter of defects is 1 mm.Experiments were conducted on the actual defect detection process.After the redundancy analysis and optimization of the sensitivity field,the system can penetrate the 25 mm thick composite material to achieve defect detection on its adhesive layer.