【摘要】 针对现有的电阻抗成像（EIT）系统结构复杂、成本高等问题，以STM32为核心，设计一种低成本、结构简单的EIT数据采集系统，并基于Matlab开发了配套的上位机控制系统，使用一步高斯牛顿法进行图像重建，将其应用于肺部呼吸监测；同时提出了最大值等效幅值法，即将一组ADC转换值的最大值等效为所需信号的幅值，显著提升了数据解调的速度，提高了成像的实时性。所设计系统具备波形图实时显示、数据存储和图像重建等功能，且支持5～100 kHz的信号输出及数据采集。数据解调实验结果表明：与快速傅里叶变换（FFT）相比，最大值等效幅值法解调1帧数据耗费的时间减少约1.5 s，且数据的相对误差小于0.331%。成像实验结果表明，重建的图像能够有效反映呼吸过程中肺内空气量的变化，验证了所设计系统的准确性和应用于肺部呼吸监测的可行性。更多还原

【Abstract】 In allusion to existing electrical impedance tomography(EIT) systems have complex structures and high costs, a low-cost and structurally simple EIT data acquisition system is designed with STM32 as the core, and a supporting upper computer control system is developed based on Matlab. The Gaussian-Newton one-step method is used for the image reconstruction and applied to the pulmonary respiration monitoring. Meanwhile, the maximum equivalent amplitude method is proposed: the maximum value of a set of analog to digital converter(ADC) conversion values is equivalent to the amplitude of the required signal, which significantly enhances the speed of data demodulation and improves the real-time performance of imaging. The designed system encompasses real-time waveform display, data storage and image reconstruction functions, supporting signal output and data acquisition within the range of 5 kHz to 100 kHz. The data demodulation experiments indicate that, in comparison with the fast Fourier transform(FFT), the maximum equivalent amplitude method can reduce the time consumed for demodulating one frame of data by 1.5 s, and the relative error of the data is less than 0.331%. The imaging experimental results demonstrate that the reconstructed image can effectively reflect the variations in the amount of air within the lungs during the respiration process, verifying the accuracy of the designed system and its feasibility for application in pulmonary respiration monitoring.更多还原