CN116626072A - A material moisture content detection device and detection method based on microwave cavity resonance - Google Patents

A material moisture content detection device and detection method based on microwave cavity resonance Download PDF

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CN116626072A
CN116626072A CN202310657606.1A CN202310657606A CN116626072A CN 116626072 A CN116626072 A CN 116626072A CN 202310657606 A CN202310657606 A CN 202310657606A CN 116626072 A CN116626072 A CN 116626072A
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microwave
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moisture content
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李陈孝
单晓旭
徐艳蕾
何贤
周婧
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Jilin Agricultural University
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    • G01N22/00Investigating or analysing materials by the use of microwaves or radio waves, i.e. electromagnetic waves with a wavelength of one millimetre or more
    • G01N22/04Investigating moisture content

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Abstract

The invention discloses a device and a method for detecting the moisture content of a material based on microwave cavity resonance, which belong to the technical field of microwave application and comprise a detected sample, a microwave generating device, a weighing unit, a sample tank, a temperature sensor, a microwave resonant cavity, an excitation probe, a detection probe, a detector, a control unit and a display output unit; the invention controls the excitation voltage of the microwave generating device and generates a microwave signal, the microwave signal enters the microwave resonant cavity through the excitation probe and is received by the detection probe, the detection of the resonance frequency change is realized through the detection probe positioned in the microwave resonant cavity, the temperature of the detected sample is measured through the temperature sensor positioned below the sample groove, a functional relation is established, and the water content of the detected material is inverted; the invention improves the universality and the detection precision of the microwave water content detection device, and the result is not influenced by the material temperature and the accumulation condition, thereby realizing the rapid nondestructive high-precision detection of the water content of the particle, powder or liquid material.

Description

一种基于微波腔体谐振的材料含水率检测装置及检测方法A material moisture content detection device and detection method based on microwave cavity resonance

技术领域technical field

本发明属于微波应用技术领域,具体涉及一种基于微波腔体谐振的材料含水率检测装置及检测方法。The invention belongs to the field of microwave application technology, and in particular relates to a material moisture content detection device and detection method based on microwave cavity resonance.

背景技术Background technique

在粮食、土壤、化肥和石油等加工制造行业中,原材料的含水率的高低是产品质量的一项重要指标,与产品的价格密切相关。精确、有效、便捷地检测材料的含水率,已经成为检测技术领域研究的热点问题。含水率的测定包括直接测量和间接测量两种方式,直接测量方法主要采用湿基法,通过测量样品在干燥前后重量之差的比重计算含水率,但该方法的测量速度慢,同时需要对材料进行破坏,一般用于实验室中的水分标定。含水率的间接测量方法主要包括电阻法、电容法、中子法、红外法及微波法等,其特点、适用范围、测量精度各不相同。其中,微波法利用高频电磁波在空间中的光速传播特性,测量过程不破坏样品结构,因此能够满足材料含水率的快速无损检测需求,具有广泛的应用场景。In the processing and manufacturing industries of grain, soil, chemical fertilizer and petroleum, the moisture content of raw materials is an important indicator of product quality and is closely related to the price of the product. Accurate, effective and convenient detection of moisture content of materials has become a hot issue in the field of detection technology. The determination of moisture content includes two methods, direct measurement and indirect measurement. The direct measurement method mainly adopts the wet base method, and the moisture content is calculated by measuring the specific gravity of the difference between the weight of the sample before and after drying, but the measurement speed of this method is slow, and at the same time, the material needs to be tested. Destruction, generally used for moisture calibration in the laboratory. The indirect measurement methods of moisture content mainly include resistance method, capacitance method, neutron method, infrared method and microwave method, etc., and their characteristics, scope of application and measurement accuracy are different. Among them, the microwave method uses the light-speed propagation characteristics of high-frequency electromagnetic waves in space, and the measurement process does not destroy the sample structure, so it can meet the needs of rapid non-destructive testing of the moisture content of materials and has a wide range of application scenarios.

在微波频率下,水的复介电常数远高于其他干物质,因此通过测量微波与材料相互作用后,功率衰减、相位变化等与介电常数相关的物理量,便能间接测得材料的含水率。微波具有穿透性,测量结果反映了样品整体含水率情况,因此更具代表性。At microwave frequency, the complex permittivity of water is much higher than that of other dry substances. Therefore, by measuring the physical quantities related to permittivity, such as power attenuation and phase change after the microwave interacts with the material, the water content of the material can be measured indirectly. Rate. Microwaves are penetrating, and the measurement results reflect the overall water content of the sample, so they are more representative.

基于微波技术的材料含水率检测主要分为空间波法、传输线法和谐振腔法,其中空间波法一般适用于大批量样品的连续在线检测,微波与被测样品相互作用后,空间微波会产生反射、透射及散射现象,电磁波的多重反射会降低含水率测量精度。传输线法传感器需要与被测材料直接接触,测量过程对材料的取样的均匀性要求很高。目前基于谐振腔法的材料含水率测量过程中,样品需要均匀填充于腔体内部,并与微波探针直接接触,无法在短时间内对不同种样品进行快速高精度检测。基于以上现状,研究和开发经济实用、普适性强、高精度的微波含水率检测方法与装置具有重要意义。The moisture content detection of materials based on microwave technology is mainly divided into space wave method, transmission line method and resonant cavity method, among which the space wave method is generally suitable for continuous on-line detection of a large number of samples. After the microwave interacts with the tested sample, the space microwave will produce Reflection, transmission and scattering phenomena, multiple reflections of electromagnetic waves will reduce the accuracy of water content measurement. The transmission line method sensor needs to be in direct contact with the material to be measured, and the measurement process has high requirements on the uniformity of material sampling. At present, in the process of measuring the moisture content of materials based on the resonant cavity method, the sample needs to be evenly filled inside the cavity and directly contacted with the microwave probe, so it is impossible to perform fast and high-precision detection of different samples in a short time. Based on the above status quo, it is of great significance to research and develop economical, practical, universal, and high-precision microwave water content detection methods and devices.

发明内容Contents of the invention

针对现有技术中存在的上述问题,本发明提供了一种基于微波腔体谐振的材料含水率检测装置及其检测方法,当微波频率与腔体固有频率匹配时,会产生谐振,谐振频率的大小与腔体内被测样品的含水率相关,本发明通过检测谐振频率的变化,建立函数关系式,反演被测材料的含水率;该检测装置可以实现对颗粒、粉末或液体材料含水率的快速无损检测,装置结构简单,测量精度高。Aiming at the above-mentioned problems existing in the prior art, the present invention provides a material moisture content detection device and detection method based on microwave cavity resonance. When the microwave frequency matches the natural frequency of the cavity, resonance will occur, and the resonance frequency The size is related to the water content of the sample to be tested in the cavity. The present invention establishes a functional relationship by detecting the change of the resonant frequency, and inverts the water content of the material to be tested; the detection device can realize the water content of the particle, powder or liquid material Fast non-destructive testing, simple device structure and high measurement accuracy.

本发明通过如下技术方案实现:The present invention realizes through following technical scheme:

一种基于微波腔体谐振的材料含水率检测装置,包括被测样品1、微波发生装置2、称重单元3、样品槽4、温度传感器5、微波谐振腔6、激励探针7、检测探针8、检波器9、控制单元10及显示输出单元11;其中,所述微波发生装置2用于产生扫频微波信号,通过同轴线与激励探针7相连,将微波激励信号传输进入微波谐振腔6内,腔体内传播后的微波信号经检测探针8接收后,通过同轴线传输至微波谐振腔6外的检波器9,进行功率检测;所述称重单元3位于微波谐振腔6的底部,用于记录空载时的重量以及满载物料时的重量;所述样品槽4位于微波谐振腔6的顶部,样品槽4的下方设有温度传感器5,用于实时测量被测样品1的温度;所述控制单元10通过信号线分别与检波器9、温度传感器5及称重单元3连接,并对微波发生装置2的激励电压进行控制,控制单元10根据读取的检波电压、温度及重量信息,通过内部函数计算被测样品1的含水率信息,并将测量结果通过显示输出单元11输出。A material moisture content detection device based on microwave cavity resonance, including a sample to be tested 1, a microwave generating device 2, a weighing unit 3, a sample tank 4, a temperature sensor 5, a microwave resonant cavity 6, an excitation probe 7, a detection probe Needle 8, wave detector 9, control unit 10 and display output unit 11; wherein, the microwave generating device 2 is used to generate frequency-sweeping microwave signals, connected to the excitation probe 7 through a coaxial line, and transmits the microwave excitation signal into the microwave In the resonant cavity 6, after the microwave signal propagated in the cavity is received by the detection probe 8, it is transmitted to the detector 9 outside the microwave resonant cavity 6 through the coaxial line for power detection; the weighing unit 3 is located in the microwave resonant cavity The bottom of 6 is used to record the weight when it is empty and the weight when it is fully loaded with materials; the sample tank 4 is located on the top of the microwave resonator 6, and a temperature sensor 5 is provided below the sample tank 4 for real-time measurement of the sample to be tested 1 temperature; the control unit 10 is respectively connected with the wave detector 9, the temperature sensor 5 and the weighing unit 3 through signal wires, and controls the excitation voltage of the microwave generator 2, and the control unit 10 is based on the detection voltage read, For the temperature and weight information, the water content information of the sample 1 to be tested is calculated through internal functions, and the measurement results are output through the display and output unit 11 .

进一步地,所述被测样品1为粮食、土壤、肥料等密度分布均匀的非金属含水材料。Furthermore, the tested sample 1 is a non-metallic water-containing material with uniform density distribution such as grain, soil, and fertilizer.

进一步地,所述微波发生装置2为压控扫频信号源,电压控制范围为0-5V,频率输出在3GHz-12GHz范围内。Further, the microwave generating device 2 is a voltage-controlled sweep signal source, the voltage control range is 0-5V, and the frequency output is in the range of 3GHz-12GHz.

进一步地,所述样品槽4为带盖圆柱形结构,为金属材质,高度范围为30-70mm,位于谐振腔的顶部,底部为非金属隔板,可以是陶瓷、塑料或玻璃等对微波低衰减材质,与谐振腔6相连接,组成谐振腔的一部分。Further, the sample tank 4 is a cylindrical structure with a cover, made of metal, with a height range of 30-70 mm, located on the top of the resonant cavity, and a non-metallic partition at the bottom, which can be made of ceramics, plastics or glass, etc., which are low in microwave resistance. The attenuation material is connected with the resonant cavity 6 to form a part of the resonant cavity.

进一步地,所述温度传感器5的温度测量有效范围不低于0-100℃,精度不低于±0.5℃。Further, the temperature measurement effective range of the temperature sensor 5 is not lower than 0-100°C, and the accuracy is not lower than ±0.5°C.

进一步地,所述微波谐振腔6为圆柱形结构,为金属材料,腔体内部半径范围为10-40mm,腔长范围为20-80mm。Further, the microwave resonant cavity 6 is a cylindrical structure made of metal material, the inner radius of the cavity is 10-40 mm, and the cavity length is 20-80 mm.

进一步地,所述激励探针7、检测探针8均为金属材料,均垂直插入微波谐振腔6的腔壁,两探针在微波谐振腔6的腔内呈90°,垂直腔体耦合的长度范围为5-20mm。Further, the excitation probe 7 and the detection probe 8 are all metal materials, and are vertically inserted into the cavity wall of the microwave resonator 6, and the two probes are 90° in the cavity of the microwave resonator 6, and the vertical cavity coupling The length range is 5-20mm.

进一步地,所述控制单元10包括电源、A/D转换器、D/A转换器及单片机运算控制单元,其中,A/D转换器用于将检波器9输出的检波电压信号转换为数字量供单片机内部运算,A/D转换器的有效位数不低于12位;D/A转换器用于将单片机控制信号转换为电压值,控制微波发生装置2产生扫频微波信号,D/A转换器的有效位数同样不低于12位。Further, the control unit 10 includes a power supply, an A/D converter, a D/A converter and a single-chip computer operation control unit, wherein the A/D converter is used to convert the detection voltage signal output by the detector 9 into a digital quantity for supply The internal operation of the single-chip microcomputer, the effective number of digits of the A/D converter is not less than 12; the D/A converter is used to convert the control signal of the single-chip microcomputer into a voltage value, and controls the microwave generator 2 to generate a frequency-sweeping microwave signal. The D/A converter The effective number of digits is also not less than 12.

本发明的一种基于微波腔体谐振的材料含水率检测装置的测量原理说明如下:The measurement principle of a material moisture content detection device based on microwave cavity resonance of the present invention is described as follows:

对于谐振腔,当微波频率与腔体固有频率匹配时,会产生谐振,如果待测样品中含有水分,水分子会吸收一部分微波能量,导致电磁场的能量损失;这些损失最终表现为微波谐振腔的品质因数Q值降低,腔体固有频率峰值变得更加宽广,并且向低频方向移动。For a resonant cavity, when the microwave frequency matches the natural frequency of the cavity, resonance will occur. If the sample to be tested contains water, the water molecules will absorb a part of the microwave energy, resulting in energy loss in the electromagnetic field; these losses will eventually appear as microwave resonant cavity The Q value of the quality factor decreases, and the peak of the natural frequency of the cavity becomes wider and moves to the lower frequency.

对于圆柱形谐振腔,谐振频率满足如下计算关系式:For a cylindrical resonator, the resonant frequency satisfies the following calculation relation:

其中,c为光速,εm为介电常数,l为谐振腔的长度,R为半径。Among them, c is the speed of light, ε m is the dielectric constant, l is the length of the resonant cavity, and R is the radius.

对于固定尺寸的谐振腔,半径R和长度l一定,上式变换为:For a resonant cavity with a fixed size, the radius R and the length l are fixed, and the above formula is transformed into:

其中,为常数。in, is a constant.

上式说明谐振频率与介电常数直接相关。在微波频率下,水分子具有很强的偶极矩,导致水的介电常数远高于其他干物质,腔体内放置不同样品后,谐振频率的变化能够直接反应样品水分变化。The above formula shows that the resonant frequency is directly related to the dielectric constant. At microwave frequencies, water molecules have a strong dipole moment, resulting in a much higher dielectric constant of water than other dry substances. After placing different samples in the cavity, the change of resonance frequency can directly reflect the change of sample moisture.

此外,材料的介电特性同时受到温度及样品堆积情况影响,温度影响物质中水分子的能量状态,堆积密度影响物质中水分子的空间分布。对于固定容积的样品槽,其内部的样品质量变化直接反应样品的堆积密度变化。本发明装置同时对被测样品的谐振频率、温度、质量进行测量,建立具有温度和堆积密度补偿的函数关系式反演样品含水率。In addition, the dielectric properties of materials are affected by both temperature and sample stacking conditions. Temperature affects the energy state of water molecules in the material, and packing density affects the spatial distribution of water molecules in the material. For a sample tank with a fixed volume, the change in the mass of the sample inside it directly reflects the change in the bulk density of the sample. The device of the invention simultaneously measures the resonant frequency, temperature, and mass of the sample to be tested, and establishes a functional relational expression with temperature and bulk density compensation to invert the water content of the sample.

另一方面,本发明还提供了上述一种基于微波腔体谐振的材料含水率检测装置的检测方法,具体包括如下步骤:On the other hand, the present invention also provides a detection method of the above-mentioned material moisture content detection device based on microwave cavity resonance, which specifically includes the following steps:

S1、空载信号检测;S1. No-load signal detection;

保持样品槽4为空载,控制单元10控制微波发生装置2的扫频电压变化,同步检测和记录检波器9检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f0;同步测量空载时称重单元3的输出重量m0Keep the sample tank 4 unloaded, the control unit 10 controls the change of the frequency sweep voltage of the microwave generator 2, synchronously detects and records the value of the detection voltage of the detector 9, records the value of the frequency sweep voltage corresponding to the extreme point of the detection voltage, and converts it accordingly is the resonant frequency f 0 ; synchronously measure the output weight m 0 of the weighing unit 3 at no-load;

S2、满载信号检测;S2, full load signal detection;

样品填满样品槽4,控制单元10控制微波发生装置2的扫频电压变化,同步检测和记录检波器9检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f1;同步测量满载时称重单元3输出重量m1、温度传感器5输出样品温度数值T;The sample fills the sample slot 4, the control unit 10 controls the frequency sweep voltage change of the microwave generator 2, synchronously detects and records the value of the detection voltage of the detector 9, records the value of the frequency sweep voltage corresponding to the extreme point of the detection voltage, and converts it to Resonant frequency f 1 ; synchronous measurement of weighing unit 3 output weight m 1 and temperature sensor 5 output sample temperature value T when fully loaded;

S3、材料含水率运算;S3, material moisture content calculation;

控制单元10内部的单片机采用如下公式进行含水率计算:The single-chip microcomputer inside the control unit 10 adopts the following formula to calculate the moisture content:

W=a(f1-f0)/(m1-m0)+bT+cW=a(f1-f0)/(m1-m0)+bT+c

其中,W表示被测材料的含水率,f0、f1分别为空载和满载时测得的谐振频率,m0、m1分别为空载和满载时测得的重量;a、b和c是由已知含水率数据测量拟合得出的系数,T为被测样品的温度数值;Among them, W represents the water content of the material to be tested, f0 and f1 are the resonant frequencies measured at no-load and full-load respectively, m0 and m1 are the weights measured at no-load and full-load respectively; a, b and c are obtained by The coefficient obtained by fitting the moisture content data measurement, T is the temperature value of the measured sample;

S4、含水率实时显示输出;S4, real-time display output of moisture content;

控制单元10内部单片机完成含水率运算后,由显示输出单元11输出与显示被测样品1的含水率信息。After the single-chip microcomputer inside the control unit 10 completes the calculation of the moisture content, the display and output unit 11 outputs and displays the moisture content information of the tested sample 1 .

与现有技术相比,本发明的优点如下:Compared with prior art, advantage of the present invention is as follows:

(1)本发明基于微波谐振腔的工作原理,设计了一种圆柱形谐振腔结构;在实现腔体完整性的同时,具有良好的封闭性,防电磁干扰性,结构轻便,经济实用;(1) The present invention designs a cylindrical resonator structure based on the working principle of the microwave resonator; while realizing the integrity of the cavity, it has good sealing performance, anti-electromagnetic interference, light structure, economical and practical;

(2)本发明检测装置电路简单,参数获取分析处理容易,同时能够对样品温度和质量进行补偿,含水率检测精度高、速度快,适用于各种加工制造业材料的检测。(2) The detection device of the present invention has a simple circuit, easy parameter acquisition, analysis and processing, and can compensate the sample temperature and quality at the same time. The moisture content detection accuracy is high and the speed is fast, and it is suitable for the detection of various processing and manufacturing materials.

附图说明Description of drawings

为了更清楚地说明本发明具体实施方式或现有技术中的技术方案,下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍。在所有附图中,类似的元件或部分一般由类似的附图标记标识。附图中,各元件或部分并不一定按照实际的比例绘制。In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the specific embodiments or the prior art. Throughout the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, elements or parts are not necessarily drawn in actual scale.

图1为本发明的一种基于微波腔体谐振的材料含水率检测装置的结构示意图;Fig. 1 is a structural schematic diagram of a material moisture content detection device based on microwave cavity resonance of the present invention;

图2为本发明微波谐振腔体的俯视图;Fig. 2 is the top view of microwave cavity of the present invention;

图3为本发明样品槽的结构示意图;Fig. 3 is the structural representation of sample tank of the present invention;

图4为本发明检测装置的测量信号控制流程图;Fig. 4 is the measurement signal control flowchart of detection device of the present invention;

图5为本发明检测装置加样品前后的谐振频率变化示意图;Fig. 5 is a schematic diagram of the change in resonance frequency before and after adding samples to the detection device of the present invention;

图中:被测样品1、微波发生装置2、称重单元3、样品槽4以及位于样品槽4下方的温度传感器5、微波谐振腔6、激励探针7、检测探针8、检波器9、控制单元10、显示输出单元11。In the figure: the sample to be tested 1, the microwave generator 2, the weighing unit 3, the sample tank 4 and the temperature sensor 5 located below the sample tank 4, the microwave resonant cavity 6, the excitation probe 7, the detection probe 8, and the detector 9 , a control unit 10 , and a display output unit 11 .

具体实施方式Detailed ways

为清楚、完整地描述本发明所述技术方案及其具体工作过程,结合说明书附图,本发明的具体实施方式如下:In order to clearly and completely describe the technical solution of the present invention and its specific working process, in conjunction with the accompanying drawings, the specific implementation of the present invention is as follows:

实施例1Example 1

如图1所示,为本实施例的一种基于微波腔体谐振的材料含水率检测装置的结构示意图,所述装置包括被测样品1、微波发生装置2、称重单元3、样品槽4、温度传感器5、微波谐振腔6、激励探针7、检测探针8、检波器9、控制单元10及显示输出单元11;其中,所述微波发生装置2产生扫频微波信号,通过同轴线与激励探针7相连,将微波激励信号传输进入微波谐振腔6内,腔体内传播后的微波信号通过检测探针8接收;所述称重单元3位于微波谐振腔6的底部;所述样品槽4位于微波谐振腔6的顶部,样品槽4下方设有温度传感器5;所述微波发生装置2及检波器9通过同轴线与微波谐振腔6相连;所述检波器9通过同轴线与检测探针8连接;所述控制单元10通过信号线分别与检波器9、温度传感器5及称重单元3连接;所述输出显示单元11与控制单元10连接;As shown in Figure 1, it is a schematic structural diagram of a material moisture content detection device based on microwave cavity resonance in this embodiment, and the device includes a sample to be tested 1, a microwave generating device 2, a weighing unit 3, and a sample tank 4 , temperature sensor 5, microwave resonant cavity 6, excitation probe 7, detection probe 8, wave detector 9, control unit 10 and display output unit 11; The wire is connected with the excitation probe 7, and the microwave excitation signal is transmitted into the microwave resonant cavity 6, and the microwave signal propagated in the cavity is received by the detection probe 8; the weighing unit 3 is located at the bottom of the microwave resonant cavity 6; The sample tank 4 is located at the top of the microwave resonator 6, and a temperature sensor 5 is arranged below the sample tank 4; the microwave generating device 2 and the detector 9 are connected to the microwave resonator 6 through a coaxial line; The line is connected to the detection probe 8; the control unit 10 is connected to the detector 9, the temperature sensor 5 and the weighing unit 3 respectively through signal lines; the output display unit 11 is connected to the control unit 10;

在本实施例中,所述微波发生装置2为压控扫频信号源,电压控制范围为0-4.5V,扫频输出范围为8-10GHz。In this embodiment, the microwave generator 2 is a voltage-controlled frequency sweep signal source, the voltage control range is 0-4.5V, and the frequency sweep output range is 8-10GHz.

在本实施例中,所述称重单元3的称重传感器为桥式结构,最大量程3KG,精度为0.1g。In this embodiment, the weighing sensor of the weighing unit 3 is a bridge structure with a maximum capacity of 3KG and an accuracy of 0.1g.

在本实施例中,所述微波谐振腔6为圆柱形结构,不锈钢材料制作,腔体内部半径为11mm,腔长为40mm。In this embodiment, the microwave resonant cavity 6 is a cylindrical structure made of stainless steel, the inner radius of the cavity is 11 mm, and the cavity length is 40 mm.

在本实施例中,所述温度传感器5为DS18B20温度传感器,测量温度范围为-55-+125℃,精度为±0.5℃。In this embodiment, the temperature sensor 5 is a DS18B20 temperature sensor with a measurement temperature range of -55-+125°C and an accuracy of ±0.5°C.

在本实施例中,所述控制单元10包括电源、A/D转换器、D/A转换器、单片机运算控制单元,单片机运算控制单元采用32位ARM核心STM32F103系列处理器,采用3.3伏供电,芯片工作频率设置为72MHz,A/D转换器选用STM32处理器内部集成模数转换器,设定12位转换精度和1μs的单次转换采集时间。In this embodiment, the control unit 10 includes a power supply, an A/D converter, a D/A converter, and a single-chip computer operation control unit. The single-chip computer operation control unit adopts a 32-bit ARM core STM32F103 series processor, and adopts a 3.3-volt power supply. The working frequency of the chip is set to 72MHz, and the A/D converter is selected to integrate the analog-to-digital converter inside the STM32 processor, and the conversion precision of 12 bits and the acquisition time of single conversion of 1μs are set.

如图2所示,在本实施例中,所述激励探针7、检测探针8均为金属材料,长度为8mm,安装于谐振腔6的中间位置,均垂直插入微波谐振腔6的腔壁,进入腔体耦合的长度为5mm,两探针在腔内呈90°。As shown in Figure 2, in this embodiment, the excitation probe 7 and the detection probe 8 are metal materials with a length of 8 mm, installed in the middle of the resonant cavity 6, and inserted vertically into the cavity of the microwave resonant cavity 6 The wall, the length of coupling into the cavity is 5mm, and the two probes are 90°in the cavity.

如图3所示,在本实施例中,所述样品槽4为带盖圆柱形结构,为金属材质,高度为10mm,位于谐振腔的顶部,底部为陶瓷隔板,厚度为2mm,样品槽内部半径为11mm。As shown in Figure 3, in this embodiment, the sample tank 4 is a cylindrical structure with a cover, made of metal, with a height of 10 mm, located on the top of the resonant cavity, and a ceramic partition at the bottom, with a thickness of 2 mm. The inner radius is 11mm.

如图4所示,本实施例的材料含水率检测装置的信号控制过程如下:As shown in Figure 4, the signal control process of the material moisture content detection device of this embodiment is as follows:

控制单元10通过内部的D/A数模转换控制微波发生装置2的激励电压从小到大逐渐变化,产生的扫频微波信号经激励探针7进入微波谐振腔6内部,经样品槽4传播后的微波信号通过检测探针8接收;检波器9通过检测探针8对腔体内部的微波信号电压进行功率检测;称重单元3采集空载和满载的重量信息;温度传感器5采集被测样品1的温度信息;控制单元10根据读取的检波电压、温度及重量信息通过内部函数计算被测样品1的含水率信息,并将测量结果通过显示输出单元11输出。The control unit 10 controls the excitation voltage of the microwave generator 2 to gradually change from small to large through the internal D/A digital-to-analog conversion, and the generated frequency-sweeping microwave signal enters the interior of the microwave resonator 6 through the excitation probe 7 and propagates through the sample slot 4. The microwave signal is received by the detection probe 8; the wave detector 9 detects the power of the microwave signal voltage inside the cavity through the detection probe 8; the weighing unit 3 collects the weight information of no-load and full-load; the temperature sensor 5 collects the sample to be tested 1 temperature information; the control unit 10 calculates the moisture content information of the tested sample 1 through internal functions according to the read detection voltage, temperature and weight information, and outputs the measurement results through the display and output unit 11.

实施例2Example 2

本实施例中以玉米为测量对象说明检测装置的具体测量方法,经过自然晾晒的玉米初始含水率为9.8%,通过在样品中加水并不断均匀搅拌的方式最终得到6份不同含水率的玉米样品,含水率变化范围为9.8%~24.2%,为了保证样品堆积的均匀性,样品用粉碎机磨成粉末后进行测量。In this example, corn is used as the measurement object to illustrate the specific measurement method of the detection device. The initial moisture content of the naturally dried corn is 9.8%, and 6 corn samples with different moisture content are finally obtained by adding water to the sample and stirring continuously , the moisture content ranges from 9.8% to 24.2%. In order to ensure the uniformity of sample accumulation, the sample is ground into powder by a pulverizer and then measured.

本实施例提供了一种基于微波腔体谐振的材料含水率检测装置的检测方法,具体步骤如下:This embodiment provides a detection method of a material moisture content detection device based on microwave cavity resonance, and the specific steps are as follows:

S1、空载信号检测;S1. No-load signal detection;

保持样品槽4为空载,控制单元10控制微波发生装置2的扫频电压变化,同步检测和记录检波器9检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f0。同步测量空载时称重单元3输出重量m0Keep the sample tank 4 unloaded, the control unit 10 controls the change of the frequency sweep voltage of the microwave generator 2, synchronously detects and records the value of the detection voltage of the detector 9, records the value of the frequency sweep voltage corresponding to the extreme point of the detection voltage, and converts it accordingly is the resonant frequency f 0 . The weight m 0 output by the weighing unit 3 is measured synchronously without load.

S2、满载信号检测;S2, full load signal detection;

样品填满样品槽4,控制单元10控制微波发生装置2的扫频电压变化,同步检测和记录检波器9检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f1。同步测量满载时称重单元3输出重量m1、温度传感器5输出样品温度数值T。The sample fills the sample slot 4, the control unit 10 controls the frequency sweep voltage change of the microwave generator 2, synchronously detects and records the value of the detection voltage of the detector 9, records the value of the frequency sweep voltage corresponding to the extreme point of the detection voltage, and converts it to Resonant frequency f 1 . The weighing unit 3 outputs the weight m 1 and the temperature sensor 5 outputs the sample temperature value T when the load is measured synchronously.

图5所示为空载和9.8%含水率的玉米测量中谐振频率的变化对比,空载谐振频率为9.425GHz,添加样品后谐振频率为9.270GHz。Figure 5 shows the comparison of the change of resonance frequency in the measurement of corn with no load and 9.8% moisture content. The no-load resonance frequency is 9.425GHz, and the resonance frequency after adding samples is 9.270GHz.

表1列出了试验中6种不同含水率的玉米样品的含水率W、空载谐振频率f0、满载谐振频率f1、空载重量m0、满载重量m1以及样品温度T的测量结果。Table 1 lists the measurement results of moisture content W, no-load resonant frequency f 0 , full-load resonant frequency f 1 , no-load weight m 0 , full-load weight m 1 and sample temperature T of 6 corn samples with different moisture content in the test .

S3、材料含水率运算S3, material moisture content calculation

控制单元10内部的单片机使用以下公式进行含水率计算:The single-chip microcomputer inside the control unit 10 uses the following formula to calculate the moisture content:

W=a(f1-f0)/(m1-m0)+bT+cW=a(f1-f0)/(m1-m0)+bT+c

其中,W表示被测材料的含水率,f0、f1分别为空载和满载时测得的谐振频率,m0、m1分别为空载和满载时测得的重量。a、b和c是由已知含水率数据测量拟合得出的系数,T为被测样品的温度数值。对于确定的测量样品,拟合系数为常量,将表1中不同含水率W、空载谐振频率f0、满载谐振频率f1、空载重量m0、满载重量m1、样品温度T带入上述公式,通过origin数据处理软件进行线性拟合后,得到拟合系数a为632.52、b为1.43、c为5.47。Among them, W represents the moisture content of the material to be tested, f0 and f1 are the resonant frequencies measured at no-load and full-load respectively, and m0 and m1 are the weights measured at no-load and full-load respectively. a, b and c are the coefficients obtained from the fitting of known moisture content data, and T is the temperature value of the measured sample. For a determined measurement sample, the fitting coefficient is constant, and the different water content W, no-load resonant frequency f 0 , full-load resonant frequency f 1 , no-load weight m 0 , full-load weight m 1 , and sample temperature T in Table 1 are brought into After the above formula was linearly fitted by origin data processing software, the fitting coefficients a was 632.52, b was 1.43, and c was 5.47.

表1:玉米样品传感器测量数据Table 1: Corn sample sensor measurement data

S4、含水率实时显示输出S4, real-time display output of moisture content

控制单元10内部单片机完成含水率运算后,由显示输出单元11输出与显示被测样品1的含水率信息。After the single-chip microcomputer inside the control unit 10 completes the calculation of the moisture content, the display and output unit 11 outputs and displays the moisture content information of the tested sample 1 .

以上结合附图详细描述了本发明的优选实施方式,但是,本发明并不限于上述实施方式中的具体细节,在本发明的技术构思范围内,可以对本发明的技术方案进行多种简单变型,这些简单变型均属于本发明的保护范围。The preferred embodiment of the present invention has been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the specific details of the above embodiment, within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, These simple modifications all belong to the protection scope of the present invention.

另外需要说明的是,在上述具体实施方式中所描述的各个具体技术特征,在不矛盾的情况下,可以通过任何合适的方式进行组合,为了避免不必要的重复,本发明对各种可能的组合方式不再另行说明。In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

此外,本发明的各种不同的实施方式之间也可以进行任意组合,只要其不违背本发明的思想,其同样应当视为本发明所公开的内容。In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (9)

1.一种基于微波腔体谐振的材料含水率检测装置,其特征在于,包括被测样品(1)、微波发生装置(2)、称重单元(3)、样品槽(4)、温度传感器(5)、微波谐振腔(6)、激励探针(7)、检测探针(8)、检波器(9)、控制单元(10)及显示输出单元(11);其中,所述微波发生装置(2)用于产生扫频微波信号,通过同轴线与激励探针(7)相连,将微波激励信号传输进入微波谐振腔(6)内,腔体内传播后的微波信号经检测探针(8)接收后,通过同轴线传输至微波谐振腔(6)外的检波器(9),进行功率检测;所述称重单元(3)位于微波谐振腔(6)的底部,用于记录空载时的重量以及满载物料时的重量;所述样品槽(4)位于微波谐振腔(6)的顶部,样品槽(4)的下方设有温度传感器(5),用于实时测量被测样品(1)的温度;所述控制单元(10)通过信号线分别与检波器(9)、温度传感器(5)及称重单元(3)连接,并对微波发生装置(2)的激励电压进行控制,控制单元(10)根据读取的检波电压、温度及重量信息,通过内部函数计算被测样品(1)的含水率信息,并将测量结果通过显示输出单元(11)输出。1. A material moisture content detection device based on microwave cavity resonance, characterized in that it includes a sample to be tested (1), a microwave generating device (2), a weighing unit (3), a sample tank (4), a temperature sensor (5), microwave resonant cavity (6), excitation probe (7), detection probe (8), wave detector (9), control unit (10) and display output unit (11); wherein, the microwave generation The device (2) is used to generate a frequency-sweeping microwave signal, which is connected to the excitation probe (7) through a coaxial line, and transmits the microwave excitation signal into the microwave resonator cavity (6), and the microwave signal propagated in the cavity passes through the detection probe (8) After receiving, it is transmitted to the detector (9) outside the microwave resonator (6) through the coaxial line for power detection; the weighing unit (3) is located at the bottom of the microwave resonator (6) for Record the weight when unloaded and the weight when fully loaded with materials; the sample tank (4) is positioned at the top of the microwave resonator (6), and a temperature sensor (5) is provided below the sample tank (4) for real-time measurement Measure the temperature of the sample (1); the control unit (10) is respectively connected with the detector (9), the temperature sensor (5) and the weighing unit (3) through the signal line, and the excitation of the microwave generating device (2) The voltage is controlled, and the control unit (10) calculates the moisture content information of the tested sample (1) through an internal function according to the read detection voltage, temperature and weight information, and outputs the measurement result through the display output unit (11). 2.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述被测样品(1)为粮食、土壤、肥料等密度分布均匀的非金属含水材料。2. a kind of material moisture content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described tested sample (1) is the non-metallic water-containing material with uniform density distribution such as grain, soil, fertilizer . 3.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述微波发生装置(2)为压控扫频信号源,电压控制范围为0-5V,频率输出在3GHz-12GHz范围内。3. A kind of material water content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described microwave generation device (2) is voltage-controlled frequency sweep signal source, and voltage control range is 0-5V , the frequency output is in the range of 3GHz-12GHz. 4.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述样品槽(4)为带盖圆柱形结构,为金属材质,高度范围为30-70mm,位于谐振腔的顶部,底部为非金属隔板,是陶瓷、塑料或玻璃对微波低衰减材质,与谐振腔(6)相连接,组成谐振腔的一部分。4. A kind of material moisture content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described sample tank (4) is the cylindrical structure with cover, is metal material, and height range is 30- 70mm, located on the top of the resonant cavity, and the bottom is a non-metallic partition, which is made of ceramics, plastics or glass with low microwave attenuation, connected with the resonant cavity (6) to form a part of the resonant cavity. 5.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述温度传感器(5)的温度测量有效范围不低于0-100℃,精度不低于±0.5℃。5. A material moisture content detection device based on microwave cavity resonance according to claim 1, characterized in that the temperature measurement effective range of the temperature sensor (5) is not lower than 0-100°C, and the accuracy is not low at ±0.5°C. 6.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述微波谐振腔(6)为圆柱形结构,为金属材料,腔体内部半径范围为10-40mm,腔长范围为20-80mm。6. a kind of material water content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described microwave resonant cavity (6) is a cylindrical structure, is a metal material, and the inner radius range of the cavity is 10-40mm, the cavity length range is 20-80mm. 7.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述激励探针(7)、检测探针(8)均为金属材料,均垂直插入微波谐振腔(6)的腔壁,两探针在微波谐振腔(6)的腔内呈90°,垂直腔体耦合的长度范围为5-20mm。7. A kind of material water content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described excitation probe (7), detection probe (8) are all metal materials, all vertically inserted The cavity wall of the microwave resonant cavity (6), the two probes in the cavity of the microwave resonant cavity (6) form a 90° angle, and the length range of vertical cavity coupling is 5-20mm. 8.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置,其特征在于,所述控制单元(10)包括电源、A/D转换器、D/A转换器及单片机运算控制单元,其中,A/D转换器用于将检波器(9)输出的检波电压信号转换为数字量供单片机内部运算,A/D转换器的有效位数不低于12位;D/A转换器用于将单片机控制信号转换为电压值,控制微波发生装置(2)产生扫频微波信号,D/A转换器的有效位数同样不低于12位。8. A kind of material water content detection device based on microwave cavity resonance as claimed in claim 1, is characterized in that, described control unit (10) comprises power supply, A/D converter, D/A converter and single-chip microcomputer Operation control unit, wherein the A/D converter is used to convert the detection voltage signal output by the detector (9) into a digital quantity for the internal calculation of the single-chip microcomputer, and the effective number of bits of the A/D converter is not less than 12; D/A The converter is used to convert the single-chip microcomputer control signal into a voltage value, and controls the microwave generating device (2) to generate frequency-sweeping microwave signals, and the effective number of bits of the D/A converter is also not less than 12 bits. 9.如权利要求1所述的一种基于微波腔体谐振的材料含水率检测装置的检测方法,其特征在于,具体包括如下步骤:9. The detection method of a material moisture content detection device based on microwave cavity resonance as claimed in claim 1, characterized in that, it specifically comprises the following steps: S1、空载信号检测;S1. No-load signal detection; 保持样品槽(4)为空载,控制单元(10)控制微波发生装置(2)的扫频电压变化,同步检测和记录检波器(9)检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f0;同步测量空载时称重单元(3)的输出重量m0Keep the sample tank (4) as no-load, the control unit (10) controls the frequency sweep voltage change of the microwave generator (2), synchronously detects and records the value of the detection voltage of the detector (9), and records the value corresponding to the extreme point of the detection voltage The numerical value of the frequency sweep voltage is correspondingly converted into the resonant frequency f 0 ; the output weight m 0 of the weighing unit (3) is measured synchronously without load; S2、满载信号检测;S2, full load signal detection; 样品填满样品槽(4),控制单元(10)控制微波发生装置(2)的扫频电压变化,同步检测和记录检波器(9)检波电压的数值,记录检波电压极值点对应的扫频电压的数值,对应转换为谐振频率f1;同步测量满载时称重单元(3)输出重量m1、温度传感器(5)输出样品温度数值T;The sample fills the sample slot (4), the control unit (10) controls the frequency sweep voltage change of the microwave generator (2), simultaneously detects and records the value of the detection voltage of the detector (9), and records the sweep corresponding to the extreme point of the detection voltage. The value of the frequency voltage is correspondingly converted into the resonant frequency f 1 ; the weighing unit (3) outputs the weight m 1 and the temperature sensor (5) outputs the sample temperature value T when it is fully loaded; S3、材料含水率运算;S3, material moisture content calculation; 控制单元(10)内部的单片机采用如下公式进行含水率计算:The single-chip microcomputer inside the control unit (10) adopts the following formula to calculate the moisture content: W=a(f1-f0)/(m1-m0)+bT+cW=a(f1-f0)/(m1-m0)+bT+c 其中,W表示被测材料的含水率,f0、f1分别为空载和满载时测得的谐振频率,m0、m1分别为空载和满载时测得的重量;a、b和c是由已知含水率数据测量拟合得出的系数,T为被测样品的温度数值;Among them, W represents the water content of the material to be tested, f0 and f1 are the resonant frequencies measured at no-load and full-load respectively, m0 and m1 are the weights measured at no-load and full-load respectively; a, b and c are obtained by The coefficient obtained by fitting the moisture content data measurement, T is the temperature value of the measured sample; S4、含水率实时显示输出;S4, real-time display output of moisture content; 控制单元(10)内部单片机完成含水率运算后,由显示输出单元(11)输出与显示被测样品(1)的含水率信息。After the single-chip microcomputer in the control unit (10) completes the calculation of the moisture content, the display output unit (11) outputs and displays the moisture content information of the sample (1) to be tested.
CN202310657606.1A 2023-06-06 2023-06-06 A material moisture content detection device and detection method based on microwave cavity resonance Pending CN116626072A (en)

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