Research On The Detection Technology Based On Scanning Imaging Of Coplanar Array Capacitance Sensor

The bonding quality problems of thermal insulation material on the surface of hypersonic vehicle in the process of preparation and service will reduce the safety of the vehicle,produce potential safety hazards,and even cause huge losses.In order to solve the problem of adhesive quality detection of composite materials used in thermal protection system,considering the characteristics of sound absorption,porosity and anisotropy of composite materials,aiming at the problem of damage detection of composite materials used in thermal protection system whose detection area is far larger than the sensor area,a research on the detection technology based on scanning imaging of coplanar array capacitance sensor is carried out.This paper studies in the following aspects:Based on the analysis the basic principles of the coplanar array capacitance imaging technology,the mathematical model of the coplanar array capacitance imaging is analyzed,the positive and negative problems of the coplanar array capacitance imaging technology are studied,and the common image reconstruction algorithms are analyzed.To solve the problem that environmental noise can reduce the quality of reconstructed image of the coplanar array capacitance sensor,a sensitivity field optimization method based on weighted coefficient method is proposed.This method analyzes the sensitivity of each capacitance value to the solution element.By analyzing the sensitivity of each capacitance value to the solving unit,the sensitivity field is obtained by suppressing the reconstructed coefficient of capacitances with low signal-to-noise ratio and improving the reconstructed coefficient of capacitances with high signal-to-noise ratio.The feasibility of this method in practical measurement is proved by experiments.For the damage detection of large area thermal insulation material,the research on the moving scan detection method of thermal insulation material based on the coplanar array capacitive sensor is carried out.The method of wavelet image fusion is used to realize the image reconstruction of moving scanning detection of coplanar array capacitance sensor.The simulation experiment is designed.The reconstructed image can identify the location and size of defects,which verifies the validity and feasibility of the method.