本文選題：電磁層析成像 + 線圈傳感器��； 參考：《遼寧大學》2015年碩士論文

【摘要】：電磁層析成像(Electromagnetic Tomography,EMT)技術是近幾年來發(fā)展起來的一種新型無損的過程檢測技術。它將麥克斯韋電磁感應理論與“由投影重建圖像”的理論相結合。而且由于其電磁傳感器具有可遠程檢測,非接觸和無危害等檢測優(yōu)點,因此可廣泛應用于工業(yè)過程中化工分離、環(huán)境監(jiān)測、地質勘探及醫(yī)學研究等領域。本文在查閱了大量國內外文獻的基礎上,分析了電磁層析成像系統(tǒng)的國內外研究現(xiàn)狀,詳細闡述了電磁層析成像系統(tǒng)基本原理;然后對電磁層析成像系統(tǒng)進行了設計,該系統(tǒng)主要包括為硬件電路部分及軟件部分。硬件電路包括傳感器陣列、激勵源信號電路、多路開關電路、采集放大電路及相敏檢波電路,軟件部分主要利用C語言、matlab語言和labview軟件進行設計。主要完成了以下幾點工作:1、設計了電磁層析成像的系統(tǒng)電路。首先為了獲得高精度,低失真的正弦波信號,采用了DDS芯片AD9850作為系統(tǒng)的激勵源;然后采用舌簧繼電器G6K-2P-Y作為多路開關電路的開關部分,實現(xiàn)對輸入線圈傳感器的電信號進行絕對物理隔離和物理連接控制;然后采用具有優(yōu)異信噪比的精密程控增益放大器AD603作為采集放大電路的前置放大器,將淹沒在噪聲中的微弱電信號提取出來;最后采用乘法器AD534對檢測信號進行硬件乘法解調,獲得比數(shù)字乘法解調更為精確的電壓信號。2、實現(xiàn)了對系統(tǒng)軟件的編程。首先利用C語言對STM32核心板編程實現(xiàn)了對多路開關進行邏輯控制,并對28組檢測電壓信號進行數(shù)據(jù)采集和處理;利用matlab語言進行圖像重建程序設計;然后在labview界面中使用VISA模塊和matlab script節(jié)點實現(xiàn)對數(shù)據(jù)的讀取與界面編程。3、搭建了電磁層析成像系統(tǒng)實驗平臺,并進行了仿真實驗,實驗結果表明在本系統(tǒng)硬件電路平臺和軟件編程基礎上實現(xiàn)了微弱檢測信號的采集與放大、多路開關控制、數(shù)據(jù)傳輸與處理、重建圖像顯示。實驗結果達到了預期要求。
[Abstract]:Electromagnetic Tomography (EMT) is a new nondestructive process detection technique developed in recent years.It combines Maxwell's electromagnetic induction theory with the "image reconstruction from projection" theory.Because its electromagnetic sensor has the advantages of remote detection, non-contact and non-hazard detection, it can be widely used in the industrial process of chemical separation, environmental monitoring, geological exploration and medical research and other fields.On the basis of consulting a large number of literatures at home and abroad, this paper analyzes the current research situation of electromagnetic tomography system at home and abroad, expounds the basic principle of electromagnetic tomography system in detail, and then designs the electromagnetic tomography system.The system mainly includes hardware circuit and software.The hardware circuit includes sensor array, excitation source signal circuit, multiplex switch circuit, acquisition amplifier circuit and phase sensitive detection circuit. The software is mainly designed with C language and labview software.The main work is as follows: 1. The system circuit of electromagnetic tomography is designed.In order to obtain high precision and low distortion sinusoidal signal, the DDS chip AD9850 is used as the excitation source of the system, and the tongue spring relay G6K-2P-Y is used as the switch part of the multiplex switch circuit.To realize the absolute physical isolation and physical connection control of the electrical signal of the input coil sensor, and then use the precision program-controlled gain amplifier (AD603) with excellent SNR as the preamplifier of the acquisition amplifier circuit.The weak electrical signal submerged in noise is extracted, and the detection signal is demodulated by hardware multiplication using multiplier AD534. The voltage signal .2is more accurate than digital multiplication demodulation, and the software of the system is programmed.Firstly, the STM32 core board is programmed with C language to realize the logic control of the multiplex switch, and 28 groups of detecting voltage signals are collected and processed, and the image reconstruction program is designed by using the matlab language.Then the data reading and interface programming. 3 are realized by using VISA module and matlab script node in the labview interface. The experiment platform of electromagnetic tomography system is built, and the simulation experiment is carried out.The experimental results show that the acquisition and amplification of weak detection signal, the control of multi-switch, the data transmission and processing, and the reconstruction of image display are realized on the basis of the hardware circuit platform and software programming of the system.The experimental results meet the expected requirements.
【學位授予單位】：遼寧大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB302.5

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