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

【摘要】：電磁層析成像(Electromagnetic Tomography,EMT)技術(shù)是近幾年來(lái)發(fā)展起來(lái)的一種新型無(wú)損的過(guò)程檢測(cè)技術(shù)。它將麥克斯韋電磁感應(yīng)理論與“由投影重建圖像”的理論相結(jié)合。而且由于其電磁傳感器具有可遠(yuǎn)程檢測(cè),非接觸和無(wú)危害等檢測(cè)優(yōu)點(diǎn),因此可廣泛應(yīng)用于工業(yè)過(guò)程中化工分離、環(huán)境監(jiān)測(cè)、地質(zhì)勘探及醫(yī)學(xué)研究等領(lǐng)域。本文在查閱了大量國(guó)內(nèi)外文獻(xiàn)的基礎(chǔ)上,分析了電磁層析成像系統(tǒng)的國(guó)內(nèi)外研究現(xiàn)狀,詳細(xì)闡述了電磁層析成像系統(tǒng)基本原理;然后對(duì)電磁層析成像系統(tǒng)進(jìn)行了設(shè)計(jì),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(lì)源信號(hào)電路、多路開(kāi)關(guān)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(yǔ)言、matlab語(yǔ)言和labview軟件進(jìn)行設(shè)計(jì)。主要完成了以下幾點(diǎn)工作:1、設(shè)計(jì)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(hào),采用了DDS芯片AD9850作為系統(tǒng)的激勵(lì)源;然后采用舌簧繼電器G6K-2P-Y作為多路開(kāi)關(guān)電路的開(kāi)關(guān)部分,實(shí)現(xiàn)對(duì)輸入線圈傳感器的電信號(hào)進(jìn)行絕對(duì)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(méi)在噪聲中的微弱電信號(hào)提取出來(lái);最后采用乘法器AD534對(duì)檢測(cè)信號(hào)進(jìn)行硬件乘法解調(diào),獲得比數(shù)字乘法解調(diào)更為精確的電壓信號(hào)。2、實(shí)現(xiàn)了對(duì)系統(tǒng)軟件的編程。首先利用C語(yǔ)言對(duì)STM32核心板編程實(shí)現(xiàn)了對(duì)多路開(kāi)關(guān)進(jìn)行邏輯控制,并對(duì)28組檢測(cè)電壓信號(hào)進(jìn)行數(shù)據(jù)采集和處理;利用matlab語(yǔ)言進(jìn)行圖像重建程序設(shè)計(jì);然后在labview界面中使用VISA模塊和matlab script節(jié)點(diǎn)實(shí)現(xiàn)對(duì)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(shí)驗(yàn)平臺(tái),并進(jìn)行了仿真實(shí)驗(yàn),實(shí)驗(yàn)結(jié)果表明在本系統(tǒng)硬件電路平臺(tái)和軟件編程基礎(chǔ)上實(shí)現(xiàn)了微弱檢測(cè)信號(hào)的采集與放大、多路開(kāi)關(guān)控制、數(shù)據(jù)傳輸與處理、重建圖像顯示。實(shí)驗(yàn)結(jié)果達(dá)到了預(yù)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(xué)位授予單位】：遼寧大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TB302.5

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