Design Of Electromagnetic Tomography System Based On LDC1000

Electromagnetic tomography technology is one of the important branches of electrical tomography technology.It is based on the principle of electromagnetic induction,through measuring the boundary information of the measured object field,and then using the image reconstruction algorithm to obtain the distribution image of the measured object field.Electromagnetic tomography system has the advantages of non-contact,simple and flexible structure,non-destructive,etc.It is widely used in metal detection,medical research,geological exploration,mining and metallurgy and other fields.With the unremitting efforts of many researchers over the past decades,the electromagnetic tomography system has developed rapidly,but the EMT technology is not mature enough.The realization of this technology has some problems and difficulties,such as the poor anti-interference ability of the system,the vulnerability to external interference,the high cost of the system and so on.Therefore,there are many theoretical studies and engineering practices of EMT technology that need to be studied and explored by researchers.The development of EMT technology has important significance and value for industrial production and medical testing.In order to enhance the anti-jamming ability of EMT system,realize automatic measurement,reduce system cost and improve image reconstruction quality,an electromagnetic tomography system based on LDC1000 inductance sensor is designed in this paper,which has the characteristics of high anti-interference ability,high resolution,low power consumption and low cost.This paper mainly focuses on the following aspects:1.On the basis of reading a lot of literatures about electromagnetic tomography system,this paper summarizes the research status of electromagnetic tomography system design at home and abroad.Based on the analysis of various electromagnetic tomography systems,according to the characteristics of LDC1000,an overall design scheme of EMT system based on LDC1000 is proposed.In addition,the principle of sensor array module,data acquisition and processing module,data communication module,multi-channel switch control module and image reconstruction module are analyzed,and then the hardware and software design of EMT system based on LDC1000 is completed.2.The EMT system based on LDC1000 takes STM32 control board as control core and LDC1000 inductance sensor as data acquisition chip.The hardware design mainly completes the design of sensor array,the connection mode of STM32 and LDC1000,the design of SPI communication between them,the design of multi-switch,the design of serial communication between lower computer and upper computer,etc.3.The software design of EMT system based on LDC1000 mainly completes the lower computer program based on STM32 and the upper computer software design based on Labview.The lower computer program mainly includes the configuration and data reading of LDC1000 register,the logic of STM32 controlling multiplexer switch,the communication between STM32 and LDC1000,and the communication between STM32 and Labview upper computer.The upper computer program mainly includes interface design,serial port configuration,data reading and writing,image reconstruction and so on.In order to improve the stability and reliability of the system,the following processing is done in the lower computer programming: every time different switches are closed or disconnected,the program is delayed to reduce the impact of the relay switch on the measured data;the data collected by the sensor is filtered and the average value of multiple measurements is processed.4.In order to improve the quality of image reconstruction,according to the feature that LDC1000 can detect the distance between the sensor coil and the measured conductor,a general imaging region of the measured conductor in the object field is determined according to the distance between the sensor coil array and the measured conductor,and then the image reconstruction results obtained by the image reconstruction algorithm are filtered by this region,so as to improve the quality of image reconstruction.5.Finally,the experimental platform of the electromagnetic tomography imaging system is built and the system simulation experiment is carried out.Firstly,image reconstruction experiments are carried out for different positions of a single copper rod in the measured field,and then image reconstruction experiments are carried out for two copper rods in the field.The results of image reconstruction are basically the same as the positions of copper rods in the object.The feasibility and reliability of the system are verified by experiments.The system designed in this paper also lays a foundation for further research of EMT system based on LDC1000 in the future.