Design Of Capacitance Sensing System For Edge Field On The Same Plane And Exploration Of Application

The in-plane capacitance detection technology is a non-destructive testing technology based on the edge effect of capacitors.Due to its simple structure,wide detection range,and good dynamic response characteristics,it has broad application prospects in aerospace,military,industrial and other fields.Moreover,it is suitable for detecting internal defects in adhesive materials with complex structures,so it has important research significance.However,due to the serious "pathological" characteristics of the same plane array capacitance imaging process,problems such as blurred image boundaries and artifacts occur,which affect detection accuracy.Therefore,this article uses a pair of electrode edge field capacitance sensors on the same surface to avoid the process of reconstructing the same surface capacitance image through dynamic scanning.The overall research content is as follows:Firstly,considering the influence of the "soft field" effect of the same surface edge field electrode on sensing performance,the design model and optimization method of the same surface electrode structure are studied.By using a univariate approach and using performance indicators as variables,the influence law between sensor structural parameters and performance indicators was explored.A mathematical model of the sensor was constructed,and a design method for electrode parameters considering the detection depth of the tested object as the primary requirement was given.Secondly,a small capacitance measurement circuit with STM32 chip as the control core was designed to address the issues of weak capacitance and large stray capacitance in the same plane edge field capacitance sensor.By reducing the influence of wire shielding and improving the calibration curve,the influence of stray capacitance is reduced.By utilizing the adjustable discharge resistor inside the PCap01 chip,the problem of incomplete charging and discharging of the tested capacitor has been improved.We have built a capacitance sensor acquisition system for the same surface edge field,and completed the detection and verification of changes in the capacitance of the Pifa and Feifa levels.Finally,in response to the problems of deep,irregular,and limited automatic detection methods for ceramic tile hollowing defects,this paper applies the same surface edge field capacitance sensor to hollowing detection for the first time,and demonstrates the feasibility of hollowing detection through simulation analysis.Considering the need for detecting ceramic tile hollowing,a capacitance sensor with the same edge field was designed,and criteria for determining defect features were proposed.Then,data processing was carried out on hollowing of different shapes and positions using methods such as differencing,normalization,and numerical feature extraction.The qualitative recognition ability of the designed system for ceramic tile hollowing defects was verified through experiments.