电阻抗断层成像系统多频激励驱动电路研究与设计

发布时间：2018-03-01 06:06

本文关键词： 电阻抗断层成像 Walsh函数多频激励驱动电路　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：电阻抗断层成像(Electrical Impedance Tomography,简称EIT)技术通过在被测物体表面放置一定数量的电极,注入安全电流,测量电压信号。EIT常用于生物医学,能获取生理和病理的相关信息,得到功能性图像。该技术安全、便捷、成本低,是一种近些年快速发展的成像技术。首先,论文介绍了 EIT研究的背景、意义和国内外研究现状,阐述了 EIT的生物医学基础、电阻抗模型和成像基本原理及过程,研究了数据测量系统的各组成部分及图像重构的两种成像方法,论证了基于Walsh函数的EIT系统多频激励驱动电路。其次,论文研究了由Rademacher函数定义的Walsh函数的三种序列及各序列之间的相互关系,确立了同时多频信号的生成方法。采用bitset函数和bitget函数,在Matlab中实现了 H序转化为W序和P序,获得了任意主谐波数同时多频激励信号的离散状态值。再次,论文设计了基于FPGA的多频激励信号源和驱动电路,实现了通过红外通信设置任意激励频率,采用VerilogHDL语言编写了红外信号解调模块、LCD显示模块、时钟发生模块、信号产生模块和驱动电路模块的代码,研究了驱动电路测量频率和激励信号的关系,对各模块进行了仿真验证,解决了以往研究中只能设置一个或几个固定的激励频率的问题。此外,论文对比分析了计数器分频和DDS分频,通过仿真分析指出了 DDS分频的缺陷。最后,论文进行了多频激励驱动电路的硬件设计,包含FPGA核心电路、激励信号源电路、驱动电路和附属电路,完成了电路板的设计和制作。测试结果表明,设计的激励信号源达到了 EIT系统要求,驱动系统模拟多路开关能实现对电极的选通控制。
[Abstract]:Electrical Impedance Tomography (EITY) technology can be used in biomedicine to obtain physiological and pathological information by placing a certain number of electrodes on the surface of the object under test, injecting a safe current, measuring voltage signals, and measuring voltage signals. It is a fast developing imaging technology in recent years. Firstly, the background, significance and research status of EIT are introduced, and the biomedical foundation of EIT is described. The electrical impedance model and the basic principle and process of imaging are studied. The components of the data measurement system and two imaging methods of image reconstruction are studied, and the multi-frequency driving circuit of EIT system based on Walsh function is demonstrated. In this paper, three kinds of sequences of Walsh function defined by Rademacher function and their interrelations are studied, and the method of generating simultaneous multi-frequency signals is established. Using bitset function and bitget function, the H order is transformed into W order and P order in Matlab. The discrete state value of multi-frequency excitation signal with arbitrary main harmonic number is obtained. Thirdly, the multi-frequency excitation signal source and driving circuit based on FPGA are designed, and the arbitrary excitation frequency is set through infrared communication. The code of infrared signal demodulation module, LCD display module, clock generation module, signal generation module and drive circuit module are compiled by VerilogHDL language. The relationship between the frequency measurement of driving circuit and the excitation signal is studied. The simulation of each module solves the problem that only one or several fixed excitation frequencies can be set in the previous research. In addition, the counter frequency division and DDS frequency division are compared and analyzed in this paper. Finally, the paper designs the hardware of multi-frequency drive circuit, including FPGA core circuit, exciting signal source circuit, driving circuit and accessory circuit. The design and fabrication of the circuit board are completed. The test results show that the designed excitation signal source meets the requirements of EIT system, and the drive system simulation switch can realize the on-off control of the electrode.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH789;TN702

【相似文献】