Research Of Shallow Buried Line Detection System Based On Special Capacitance Sensor

Nowadays,the renewal of technology in the construction industry leads to the indoor pipeline has gradually changed from exposed to hidden,different laying positions make it difficult to install and maintain pipelines in the later stage.Therefore,it is necessary to solve this problem by means of pipeline detection instruments.The existing pipeline detection instruments are mainly for underground deep pipelines and are not suitable for indoor pipeline detection,Therefore,this thesis proposes a shallow buried pipeline detection system based on special capacitive sensors.The detection principle of the system is mainly utilizes the edge effect of the capacitive sensor.When the sensor is above the buried wire,the capacitance value of the capacitor changes due to the presence of the buried wire,the specific location of the buried wire can be determined by converting the change of capacitance to the change of voltage.This thesis first studied the existing micro-capacitance detection method,the working principle of the buried detection system is elaborated,through analysis and comparison,the core detection circuit of the system was determined.Secondly,using the experimental method of orthogonal programming,various models of non-parallel plate capacitive sensors were established and simulated by ANSYS software,and the optimal detection model of capacitance sensor was obtained;the hardware circuit of the system was designed by modules,the capacitance-voltage conversion module was simulated by Multisim software,the function of the module was verified,and the component parameters in the circuit were determined to maximize the resolution of the design circuit.The working time sequence of each module was analyzed,and the time sequence control program was written in hardware description language;the LabVIEW host computer communicated with the FPGA through serial port,and dynamically displayed the measurement data.Finally,a shallow embedding experiment platform was built,the system circuit function was tested,the embedding line detection experiment was carried out,and the measured data was fitted using MATLAB,the regular characteristics of input capacitance and output voltage were obtained.The circuit test shows that the capacitance detection sensitivity of the circuit can reach 0.2V/pF with 10kHz sine wave,which satisfies the sensitivity requirements of the shallow buried detection system.The embedding line detection experiment shows that the system has high stability and flexibility,which can better realize the function of detecting shallow embedding in indoor.