基于电阻抗成像技术的果树苗茎杆冻融状态辨识方法  

Identification method for the stem freezing-thawing state of fruit tree seedlings based on electrical impedance imaging technology

作　　者：姜涵 朱玉帆 颜小飞[2] 程强[1,3] JIANG Han;ZHU Yufan;YAN Xiaofei;CHENG Qiang(College of Information and Electrical Engineering,China Agricultural University,Beijing 100083,China;School of Technology,Beijing Forestry University,Beijing 100083,China;State Key Laboratory of Efficient Utilization of Agricultural Water Resources,Beijing 100083,China)

机构地区：[1]中国农业大学信息与电气工程学院,北京100083 [2]北京林业大学工学院,北京100083 [3]农业水资源高效利用全国重点实验室,北京100083

出　　处：《农业工程学报》2025年第4期193-200,共8页Transactions of the Chinese Society of Agricultural Engineering

基　　金：国家自然科学基金资助项目(32271990);拼多多-中国农业大学研究基金资助项目(PC2023A02002)。

摘　　要：为检测果树苗茎杆冻融状态,该研究提出了一种基于电阻抗成像技术的果树苗茎杆冻融状态辨识方法,设计了具有16个信号数据采集电极的电阻抗系统,系统软件主要包括基于C#开发的Windows平台上位机,以及用于解决成像正问题和逆问题的开源套件EIDORS。对该系统的性能进行了多种测试,测试包括恒流源输出阻抗测试、通道一致性测试、温度校正测试、成像效果测试、系统测量范围测试。系统测试表明:1)恒流源的仿真输出阻抗在MΩ级别,实际输出在低频时接近MΩ;2)16个电极的输出幅值较好的一致性;3)温度对系统输出有影响,在进行温度校正后,输出幅值标准差有明显下降;4)系统对3D打印模型成像结果符合预期,相比于6和9 cm,系统对直径3 cm的模拟石膏茎杆水分整体分布有着较好的成像效果,冻融试验对象定为3 cm以下的小茎杆。在实验室环境下进行了果树苗茎杆冻融试验,试验对象为直径3 cm的苹果树苗茎杆,试验结果表明:1)温度与电阻抗成像系统(electrical impedance tomography,EIT)测量的平均电导率变化趋势一致;2)从系统时差成像的2D水分分布可以观测出茎杆冻融过程。系统对直径3 cm的茎杆冻融状态具有较好的辨识结果,能够初步反应其冰水含量及其分布,可为茎杆冻融状态辨识提供思路和检测方法。Fruit trees can often suffer from the frost damage at low temperatures.The fruit tree stems can be gradually frozen to disrupt the internal water transport after cork formation.Effective identification of frost damage is required for early protective measures to reduce the losses in the yield of fruit trees.Commonly-used techniques can be used to detect the internal freezing and thawing in trees,such as calorimetry,ultrasonic emission,dielectric,nuclear magnetic resonance imaging,and X-ray imaging.However,only electrical impedance tomography(EIT)can reflect the impedance distribution in the image form,thus revealing the internal changes during freezing and thawing of fruit tree.In this study,the electrical impedance imaging was proposed to identify the freezing and thawing state of fruit tree stem.A 16-electrode EIT system was designed to connect the hardware in a stacked form,such as the power supply,signal generation,voltage-current conversion,multiplexing,signal demodulation,control unit,and temperature acquisition.In power supply module,various voltage regulators and boost converters were employed to provide the different positive and negative power supplies.While the signal generation module was used to output the stable sinusoidal voltage signals with adjustable frequency.The constant current source was utilized to serve as the enhanced Howland current source.The multiplexing module was used to switch among 16 electrode channels.The signal demodulation module was used to obtain the imaging data,and then demodulate the amplitude and phase of the measurement signal.The accuracy of this process was dominated the imaging.Analog demodulation was then chosen for this design.The control unit module was acquired and then stored the raw voltage data from EIT measurement.The wireless connections were also established with the host computer system via serial communication and Bluetooth modules.Temperature acquisition was integrated into the system as an essential part of freezing and thawing experiments.The system sof

关 键 词：电阻抗成像 茎杆 冻融 果树 状态辨识 

分 类 号：S147.2[农业科学—肥料学]