基于FPGA的块茎电阻成像数据获取系统研究

发布时间：2019-04-18 10:37

【摘要】：电阻层析成像技术(Electrical Resistance Tomography,简称ERT)是电学成像领域一个重要分支。由于其无辐射、速度快、结构简单、性价比高等优点,在工业领域应用前景广阔。本文致力于将ERT技术应用于电子农业成像,对块茎电阻成像(TERT-Tuber Electrical Resistance Tomography)技术进行了深入的研究。目的是对土壤中植物块茎的生长状态进行非侵入式的可视化监控,符合精细化农业要求。为新品种培育和电子农业提供了一种可视化检测手段和工具。基于前期对TERT系统电极阵列的仿真研究,本文设计和制作了 6层16电极阵列的TERT数据获取系统。TERT数据获取系统的技术是工业ERT技术的发展。与工业ERT系统相比,TERT系统测量场域的阻抗更大,分布不均衡;数据激励/采集使用串行方式;对成像分辨率和成像质量要求更高。因此在工业ERT数据获取系统技术的基础上,根据TERT与工业ERT的差别,设计和制作数据获取系统是本文的主要研究工作,本文主要任务包括:(1)在TERT系统阻抗模型分析和仿真研究的基础上,制作了适合TERT系统的敏感电极阵列子系统;(2)基于制作完成的敏感电极阵列子系统,设计了多组阻抗测试实验,验证了TERT系统理论的可行性,并为数据获取系统的硬件设计提供了参数依据;(3)基于FPGA的TERT数据获取系统的硬件设计与制作,包括了开关阵列控制电路板、模拟信号调理电路板和控制电路板,实现了 6层每层16电极阵列的相邻激励/测量模式下的数据获取工作;(4)基于Verilog语言编写FPGA软件程序,和基于C语言的ARM控制程序,完成了开关阵列的有序切换、数据获取控制、数字滤波以及与上位机的数据通讯;(5)基于设计完成的数据获取系统,对TERT理论进行验证,对系统进行优化,最终得到可靠的数据,并进行了植物块茎的图像重建实验。本文设计的硬件系统包括:敏感电极阵列子系统、恒流激励源、信号调理电路板、控制电路板以及6块开关阵列控制电路板。在所建立的实验硬件基础上进行了土壤阻抗测试实验和数据获取系统性能测试实验。可实现对截面面积不小于1.21 cm2且与土壤电导率不同的块状物体的场域边界电压的采集和3D图像重建。
[Abstract]:Resistance tomography (Electrical Resistance Tomography,) is an important branch of electrical imaging field. Because of its non-radiation, high speed, simple structure, high cost-to-performance and other advantages, it has a broad application prospect in the field of industry. In this paper, we focus on the application of ERT technology in electronic agriculture imaging, and make a deep research on TERT-Tuber Electrical Resistance Tomography) technology. The aim of this paper is to monitor the growth state of plant tubers in soil by non-invasive visualization, and to meet the requirements of fine agriculture. It provides a visual detection method and tool for the cultivation of new varieties and electronic agriculture. Based on the simulation of TERT system electrode array, a 6-layer 16-electrode array TERT data acquisition system is designed and fabricated in this paper. The technology of tert data acquisition system is the development of industrial ERT technology. Compared with the industrial ERT system, the measurement impedance of the TERT system is larger and the distribution is unbalanced, the serial mode is used for data excitation / acquisition, and the imaging resolution and imaging quality are higher. Therefore, based on the technology of industrial ERT data acquisition system and according to the difference between TERT and industrial ERT, the design and manufacture of data acquisition system is the main research work of this paper. The main tasks of this paper are as follows: (1) based on the impedance model analysis and simulation of TERT system, a sensitive electrode array subsystem suitable for TERT system is fabricated. (2) based on the sub-system of sensitive electrode array, a series of impedance test experiments are designed to verify the feasibility of the theory of TERT system, and provide the parameter basis for the hardware design of data acquisition system. (3) hardware design and manufacture of TERT data acquisition system based on FPGA, including switch array control circuit board, analog signal conditioning circuit board and control circuit board. The data acquisition work in the adjacent excitation / measurement mode of the 16-electrode array with 6 layers each layer is realized. (4) programming FPGA software program based on Verilog language and ARM control program based on C language, completing orderly switching of switch array, data acquisition control, digital filtering and data communication with upper computer; (5) based on the designed data acquisition system, the TERT theory is verified, the system is optimized and the reliable data is obtained, and the image reconstruction experiment of plant tuber is carried out. The hardware system designed in this paper includes: sensitive electrode array subsystem, constant current excitation source, signal conditioning circuit board, control circuit board and six switch array control circuit boards. On the basis of the experimental hardware, the soil impedance test and the performance test of data acquisition system are carried out. The field boundary voltage acquisition and 3D image reconstruction of massive objects whose cross-section area is not less than 1.21 cm2 and whose conductivity is different from soil conductivity can be realized.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN791;TP311.52

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