CN111812727B - A non-invasive nuclear magnetic resonance grain storage volume detection device and detection method - Google Patents

Abstract

The invention relates to a non-invasive nuclear magnetic resonance granary reserves detection device and a detection method. In the detection, the universal rotating bracket and the excitation coil are rotated to an angle to be detected, the main detection device starts direct current detection to excite moisture in grains, and the weak magnetic sensor array acquires nuclear magnetic resonance signals after direct current hard turn-off, so that whether adulteration occurs can be primarily judged; and then the main detection device can restart direct current and alternating current combined excitation, at the moment, the direct current is in soft turn-off, and after the excitation is finished, the weak magnetic sensor array acquires nuclear magnetic resonance signals, and stores and transmits the nuclear magnetic resonance signals to the handheld terminal for analysis. The invention uses the universal rotating bracket, the exciting coil and the array weak magnetic sensor to detect the reserve of the granary, prevents the local granary from adulteration in the process of inspection, has the advantages of no damage, high efficiency and fine imaging, and expands the application range of the nuclear magnetic resonance method.

Description

A non-invasive nuclear magnetic resonance grain storage volume detection device and detection method

technical field

The invention belongs to the technical field of granary management and grain storage volume detection, in particular to a non-invasive nuclear magnetic resonance grain storage volume detection device and detection method suitable for grain adulteration during granary inspection.

Background technique

At present, when inspecting granaries in my country, the method of combining entry and exit record accounting with actual storage situation detection is generally adopted. However, most of the existing grain storage detection methods use methods such as weighing and volume estimation. In order to quickly detect the real storage situation inside the granary, it is necessary to explore and develop a non-invasive nuclear magnetic resonance granary detection device and detection method suitable for granary detection. .

Patent CN103307976 discloses a "monitoring method for grain storage in a granary", which includes a motor, an alarm, a two-dimensional turntable, a distance measuring sensor and a computer arranged on the top of the granary. The invention measures the three-dimensional coordinate point set on the upper surface of the grain after each grain intake and grain output by the distance measuring sensor, thereby obtaining the granary model after each granary change, further calculating the volume of the granary model, and finally calculating the storage capacity of the grain.

Patent CN108958178 discloses a "monitoring system for grain storage", which is composed of a grain depot, a camera, a scanner, a weighing device and a control terminal. Cameras, scanners and weighing devices are set at the entrance of the granary, and the control terminal is located in the control room. In addition, photoelectric sensors are installed during the grain transfer process. The invention calculates the total storage capacity of the granary by weighing the grains entering and leaving the warehouse at the entrance, and uses photoelectric sensors to judge what kind of grain is and indicate the storage location, so as to realize the full monitoring of the grain storage process.

Patent CN110823334 discloses "a grain detection method and system for grain storage", which is composed of bottom surface pressure sensors arranged in the grain storage. During detection, first preprocess the output value of the pressure sensor, including retaining the output value whose difference from the average value of the sensor output value is within the set range, and then use the preprocessed sensor output value for grain storage. Quantity calculation, so as to realize the accurate detection of grain storage volume.

The granary monitoring device and monitoring method of the invention above play an important role in the statistics and management of grain storage volume. The storage volume and abnormal monitoring of the granary are realized through volume estimation, weighing detection, and weighing optimization. It is simple, fast, and accurate in measurement. High and low labor costs. However, during the inspection of the granary, the inspectors still need to calculate the storage of the granary according to the monitoring records. In addition, since it is impossible to visually view the situation inside the granary in real time, it is still impossible to judge the real situation.

Contents of the invention

The technical problem to be solved by the present invention is to provide a non-invasive nuclear magnetic resonance grain storage volume detection device, which is suitable for high-efficiency and high-resolution detection of the storage volume and grain quality inside the granary during the inspection of the granary.

The present invention is achieved like this,

A non-invasive nuclear magnetic resonance grain storage volume detection device, the device includes:

The handheld terminal adopts the communication method of wireless transmission, which is used to configure the working status and parameters of the detection device, and recover the collected magnetic resonance signal data. Through the built-in data analysis algorithm, the magnetic resonance signal obtained during the granary detection can be decompressed and analyzed in real time. And generate grain distribution cloud map and detection report;

The excitation coil carries the generated direct current and alternating current, and excites the nuclear magnetic resonance signal of the moisture in the grain;

Weak magnetic sensor array to collect nuclear magnetic resonance signals of moisture in grain;

The universal rotating bracket is used to support the weak magnetic sensor array to realize the detection in any direction in the granary;

The main detection device, by generating direct current and arbitrary waveform alternating current to the excitation coil, realizes the nuclear magnetic resonance signal excitation of the moisture inside the grain, and collects and transmits the magnetic resonance signal back to the handheld terminal for analysis by connecting the weak magnetic sensor array.

Further, the magnetic field weakening sensor array includes:

A plurality of magnetic sensors are fixed at different positions of the universal rotating bracket, and are connected to the original signal acquisition module in the main detection device through a data transmission line for the acquisition of weak magnetic signals;

The magnetic sensor detection module is connected with the magnetic sensor to monitor the state of the magnetic sensor in real time, and when the magnetic sensor is abnormal, it will actively alarm and remind.

Further, the universal rotating bracket includes a tripod bracket, a universal rotating head and a coil bracket, wherein:

Triangular bracket, connected with the universal rotor, used to support the coil bracket to maintain a certain fixed direction;

The universal rotating head is directly connected with the coil support, and can detect in different directions by rotating to any angle;

The coil support is used for fixing the shape of the coil and fixing the weak magnetic sensor array.

Further, the coil support is a square structure, and four magnetic sensors are arranged symmetrically on the diagonal of the square structure.

Further, the main detection device includes:

The wireless communication controller communicates with the handheld terminal, receives the parameter configuration and returns the compressed magnetic resonance signal data; in addition, it is connected with the general controller to control the operation of the detection device;

The master controller controls the generation of direct current according to the set detection timing.

Further, the main detection device also includes:

The high-power power supply provides energy for the output of direct current by connecting with the impedance regulator;

The impedance adjuster is connected with the excitation coil, and the energy of the high-power power supply is input to the excitation coil in a controllable manner, so as to generate the required direct current;

Arbitrary wave generator, controlled by the general controller, generates AC signals of different waveforms and frequencies;

The power amplifier is connected with the power regulator, and the power regulator is controlled by the general controller to output AC, and the arbitrary wave AC signal is amplified by the power amplifier;

The DC/AC isolation module is placed between the power amplifier and the excitation coil to avoid the mutual crosstalk between DC and AC, and only allow the generated DC and AC to act on the excitation coil;

The basic power supply provides the required power supply for the wireless communication controller, general controller, arbitrary wave generator, power amplifier, and power regulator, so as to ensure the normal operation of the detection device.

Further, the main detection device also includes:

The original signal acquisition module is connected with the weak magnetic sensor array, and collects the magnetic resonance signals obtained on each magnetic sensor;

The data is stored locally, connected with the original signal acquisition module, and the acquired signal data is stored locally for subsequent data processing and verification;

The data compression module is connected with the local data storage, transmits the compressed data to the wireless communication controller, and further sends it to the handheld terminal, so as to obtain the detection results on the spot.

Further, the device generates a direct current of 50-200A and a duration of 5s, an alternating current of 0.05A-10A and a duration of 40ms; the magnetic field sensor array continues to collect;

A non-invasive nuclear magnetic resonance grain storage detection method, comprising the following steps:

Step 1. Select the detection position, fix the coil direction, and connect the detection device;

Step 2, self-inspection after power-on of the grain storage volume detection device;

Step 3. According to the actual detection requirements, calculate the size of the impedance adjuster, adjust the size of the DC output, and set other detection parameters on the handheld terminal;

Step 4. Determine whether the data between the handheld terminal and the detection device can transmit data to each other normally, and if they cannot communicate normally, then check the handheld terminal and the detection device respectively, and re-inspect;

Step 5. Each magnetic field weakening sensor in the magnetic field weakening sensor array starts to continuously collect signals within its detection range, and starts DC detection. After the DC excitation is completed, a hard shutdown method is adopted, and the magnetic field weakening sensor array collects nuclear magnetic resonance signals at different positions;

Step 6. The data local storage module first saves the signal detected by the magnetic field weakening sensor for review of subsequent experimental results, and then sends the detected signal to the handheld terminal through the wireless communication sensor;

Step 7. The hand-held terminal is equipped with a data reconstruction algorithm to restore and express the signal transmitted to the hand-held terminal to obtain the original data information;

Step 8. After recovering the original data, the built-in algorithm of the handheld terminal further denoises the signal through means such as digital filtering and spectrum conversion, and then compares the processed relaxation signal with the theoretical signal when the grain is completely stored. When there is a difference between the relaxation signal and the theoretical signal, it is considered that there is a possibility of adulteration; when the detected relaxation signal is the same as the theoretical signal or within the error tolerance range, it is considered that there is no adulteration;

Step 9. If there is no adulteration at this detection position of the granary, then rotate or move the universal rotating bracket to detect other positions; if the preliminary analysis results find that this detection position is abnormal, start the subsequent DC and AC joint detection, Carry out detailed detection by stratifying the front to be tested, so as to further analyze the abnormal situation of the granary;

Step 10. Start the DC excitation to enhance the magnetic resonance signal strength of the grain. After the DC power is softly turned off, quickly use the AC power excitation, and the array magnetic sensor collects the nuclear magnetic resonance signals at different positions. At this time, the data is compressed and collected through steps 6 to 7. transmitted back to the handheld terminal;

Step 11. In order to avoid the influence of random noise and the like on the NMR signal, repeat step 10 to perform superimposed tests on the NMR, with less noise influence;

Step 12: Perform digital filtering and spectral transformation on the handheld terminal to further denoise the signals obtained in steps 10 and 11, and then combine the processed relaxation signals of a certain layer in front of the test with the fully stored Theoretical signal comparison of grain time, so as to obtain the accurate grain storage situation of a certain layer depth;

Step 13. According to the preset detection parameters, the direct current is kept constant, the power regulator adjusts the alternating current to the next set value, and the operations of steps 10-12 are repeated, so as to realize the determination of grain storage conditions at different depths;

Step 14, after the overall detection is completed, the reserves of each layer depth are completely drawn on a cloud map, and at this time, the complete detection process of the measuring point is completed;

Step 15. If it is necessary to detect the grain storage situation in other locations, after re-arranging the universal rotating coil, repeat steps 4-14;

Step 16. After all the measurements are completed, the handheld terminal generates a detailed detection report to obtain the actual grain storage situation inside the granary.

Compared with the prior art, the present invention has the beneficial effects of:

1. A non-invasive nuclear magnetic resonance grain storage volume detection device and detection method proposed by the present invention can ensure that during the inspection of the granary, the real grain storage status of the granary can be sampled quickly without opening the grain pile, instead of Only relying on accounting entry and exit records to achieve the purpose of inspection is convenient, safe and environmentally friendly;

2. The detection device proposed by the present invention adopts the scheme of universal rotating coil and distributed instruments, which can realize the detection of any position and any direction, avoiding the trouble of frequent wiring when changing the detection location, and is suitable for the sampling inspection of different granaries with high efficiency and fast The advantages;

3. The present invention proposes the combination of the handheld terminal and the main detection device, uses the handheld terminal to control the operation of the main detection instrument, and recovers the data, obtains the detection results of the granary in real time, draws a grain distribution cloud map, generates a report, and monitors the granary patrol. It is of guiding significance to inspect the next work arrangement;

4. The weak magnetic sensor array proposed by the present invention adopts a half-coverage layout method to meet the detection interval covering the range covered by the entire excitation coil, thereby realizing the multi-dimensional imaging capability in front of the granary to be tested, and the weak magnetic sensor array is continuously recorded in the Detecting the magnetic field changes in the granary process has the advantages of high accuracy and fast speed, so as to avoid the abnormality of the sensor at a certain moment from affecting the overall detection results;

A non-invasive nuclear magnetic resonance grain storage capacity detection device and detection method proposed by the present invention has the characteristics of non-invasive detection, accurate detection results, fast detection speed, convenience and environmental protection, and solves the problem of the inability to actually survey granaries during the traditional granary inspection process. The problem of internal actual grain storage situation, the present invention will lay an important foundation for my country's grain management and grain storage industry, and has good promotion prospect and promotion value.

Description of drawings

Fig. 1 is a schematic diagram of the working layout of a non-invasive nuclear magnetic resonance grain storage volume detection device;

Fig. 2 is a structural block diagram of a non-invasive nuclear magnetic resonance grain storage volume detection device;

Fig. 3 is a working flow diagram of a non-invasive nuclear magnetic resonance grain storage capacity detection method;

Fig. 4 is a schematic diagram of the measurement range of a magnetic sensor array;

Among them, 1 main detection device, 2 excitation connection line, 3 universal rotator, 4 weak magnetic sensor array, 5 coil support, 6 excitation coil, 7 magnetic sensor connection line, 8 tripod bracket, 9 data transmission line, 10 hand-held terminal ( APP), 11 wireless communication controller, 12 general controller, 13 high-power power supply, 14 arbitrary wave generator, 15 basic power supply, 16 impedance regulator, 17 power amplifier, 18 power regulator, 19 DC-AC isolation module, 20 Magnetic sensor monitoring module, 21 first magnetic sensor, 22 second magnetic sensor, 23 third magnetic sensor, 24 fourth magnetic sensor, 25 original signal acquisition module, 26 data local storage, 27 data compression module, 28 first magnetic sensor 29 the detection range of the second magnetic sensor, 30 the detection range of the third magnetic sensor, and 31 the detection range of the fourth magnetic sensor.

Detailed ways

In order to make the object, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Referring to Fig. 1, a kind of non-invasive nuclear magnetic resonance grain storage detection device, comprises hand-held terminal (APP) 10, weak field sensor array 4, universal rotating bracket, main detection device 9 and the excitation coil 6 of belonging; Hand-held terminal (APP) ) using a wireless transmission communication method to control the overall detection device for granary detection; the main detection device 1 is connected to the excitation coil 6 through the excitation connection line 2, thereby realizing the output of direct current and alternating current; specifically includes:

The excitation coil carries the generated direct current and alternating current to excite the nuclear magnetic resonance signal of the moisture in the grain; through the weak magnetic sensor array, the nuclear magnetic resonance signal of the moisture in the grain is collected;

The universal rotating bracket is used to support the weak magnetic sensor array to realize the detection in any direction in the granary;

The main detection device, by generating direct current and arbitrary waveform alternating current to the excitation coil, realizes the nuclear magnetic resonance signal excitation of the moisture inside the grain, and collects and transmits the magnetic resonance signal back to the handheld terminal for analysis by connecting the weak magnetic sensor array.

Among them, on the universal rotating bracket, the triangular bracket 8 is mechanically connected to the universal rotating head 3, and the universal rotating head 3 is mechanically connected to the coil support 5, thereby forming the universal rotating bracket to carry the excitation coil 6, and realizing the detection of any angle of the granary ;

Wherein, the magnetic field weakening sensor array 4 is fixed on the coil support 5 by a plurality of magnetic sensors, and the magnetic field weakening sensor array 4 is connected with the main detection device through the magnetic sensor connection line 7 and the data transmission line 9;

The field weakening sensor array includes:

A plurality of magnetic sensors are fixed at different positions of the universal rotating bracket, and are connected to the original signal acquisition module in the main detection device through a data transmission line for the acquisition of weak magnetic signals;

The magnetic sensor detection module is connected with the magnetic sensor to monitor the state of the magnetic sensor in real time, and when the magnetic sensor is abnormal, it will actively alarm and remind. The coil support is a square structure, and four magnetic sensors are arranged symmetrically on the diagonal of the square structure.

A single magnetic field weakening sensor has its own detection range, and the magnetic field weakening sensor array composed of multiple magnetic sensors is required to be fixed on the coil support, and the semi-coverage arrangement is adopted to meet the detection interval covering the entire range covered by the excitation coil;

Referring to Fig. 2, a non-invasive nuclear magnetic resonance grain storage detection device also includes a basic power supply 15 electrically connected to a wireless communication controller 11, a general controller 12, an arbitrary wave generator 14, a power amplifier 17 and a power regulator 18 respectively , and provide power supply for it; the wireless communication controller 11 communicates bidirectionally with the handheld terminal (APP) 10, receives parameters and transmits magnetic resonance signal data; the high-power power supply provides energy for the output of direct current by connecting with the impedance regulator;

The impedance adjuster is connected with the excitation coil, and the energy of the high-power power supply is input to the excitation coil in a controllable manner, so as to generate the required direct current;

Arbitrary wave generator, controlled by the general controller, generates AC signals of different waveforms and frequencies;

The power amplifier is connected with the power regulator, and the power regulator is controlled by the general controller to output AC, and the arbitrary wave AC signal is amplified by the power amplifier;

The DC/AC isolation module is placed between the power amplifier and the excitation coil to avoid the mutual crosstalk between DC and AC, and only allow the generated DC and AC to act on the excitation coil;

The basic power supply provides the required power supply for the wireless communication controller, general controller, arbitrary wave generator, power amplifier, and power regulator, so as to ensure the normal operation of the detection device.

Among them, the wireless communication controller 11 transmits the detection parameters to the general controller 12, and the high-power power supply 13 is connected to the excitation coil 6 through the impedance adjuster 16, thereby generating direct current; the arbitrary wave generator 14 amplifies the signal through the power amplifier 17, and then passes After the DC/AC isolation module 19 is connected with the exciting coil 6, thereby generating alternating current, the power regulator 18 is connected with the power amplifier 17 to adjust the size of the alternating current; the total controller 12 is respectively connected with the impedance regulator 16, the arbitrary wave generator 14, and the power regulator 18 Connect, control the output of direct current and alternating current, and control the size of direct current and alternating current at the same time; the main detection device also includes:

The original signal acquisition module is connected with the weak magnetic sensor array, and collects the magnetic resonance signals obtained on each magnetic sensor;

The data is stored locally, connected with the original signal acquisition module, and the acquired signal data is stored locally for subsequent data processing and verification;

The data compression module is connected with the local data storage, transmits the compressed data to the wireless communication controller, and further sends it to the handheld terminal, so as to obtain the detection results on the spot.

Wherein, four magnetic sensors are included in the present embodiment, respectively: the first magnetic sensor 21, the second magnetic sensor 22, the third magnetic sensor 23, and the fourth magnetic sensor 24, and the magnetic sensors are monitored by the magnetic sensor detection module 20 , the magnetic sensor is connected to the wireless communication controller 11 after the original signal collection 25 , data local storage 26 , and data compression module 27 , so as to realize data collection, storage, compression, and transmission.

In the detection device, the required direct current is 50-200A, and the duration is 5s; the alternating current is 0.05A-10A, and the duration is 40ms; the weak magnetic sensor array continues to collect;

See Figure 3, the workflow of a non-invasive nuclear magnetic resonance grain storage detection method, including power-on self-inspection, data transmission verification, direct current detection to initially determine the adulteration of the grain warehouse, joint detection of direct current and alternating current to generate a cloud map of the grain warehouse distribution, and a weak magnetic sensor The array collects signals, saves the data and sends it back to the handheld terminal (APP);

A non-invasive nuclear magnetic resonance grain storage detection method, specifically including the following process:

a. Select the detection position, fix the coil direction, and connect the detection device;

b. Self-inspection of the grain storage volume detection device after power-on;

c. According to the actual detection requirements, calculate the size of the impedance adjuster, adjust the size of the DC output, and set other detection parameters on the handheld terminal (APP);

d. Determine whether the data between the handheld terminal and the detection device can transmit data to each other normally. If they cannot communicate normally, check the handheld terminal (APP) and the detection device separately, and re-inspect;

e. Each weak magnetic sensor in the weak magnetic sensor array begins to continuously collect signals within its detection range, and starts DC detection. After the DC excitation is completed, a hard shutdown method is adopted, and the weak magnetic sensor array collects nuclear magnetic resonance signals at different positions;

f. The local data storage module first saves the signal detected by the weak magnetic sensor for review of subsequent experimental results, and then sends the detected signal to the handheld terminal (APP) through the wireless communication sensor. Considering the large amount of transmitted data, the signal to be transmitted is compressed, that is, it is sparsely represented without affecting the original data, and the memory usage is reduced;

g. The hand-held terminal (APP) is equipped with a data reconstruction algorithm, which restores the signal transmitted to the hand-held terminal (APP) and obtains the original data information;

h. After restoring the original data, the built-in algorithm of the handheld terminal (APP) further de-noises the signal through digital filtering, spectrum conversion and other means, and then compares the processed relaxation signal with the theoretical signal when the grain is completely stored. When the detected relaxation signal is different from the theoretical signal, it is considered that there is a possibility of adulteration; when the detected relaxation signal is the same as the theoretical signal or within the error tolerance range, it is considered that there is no adulteration;

i. If there is no adulteration at this detection position of the granary, then rotate or move the universal rotating bracket to detect other positions; if the preliminary analysis results find that this detection position is abnormal, then start the subsequent DC and AC joint detection, and Detailed detection is carried out layer by layer in front of the test, so as to further analyze the abnormal situation of the granary;

j. Start the DC excitation to enhance the magnetic resonance signal strength of the grain. After the DC power is softly shut down, use the AC current excitation quickly, and the array magnetic sensor collects the nuclear magnetic resonance signals at different positions. At this time, the data is compressed and transmitted through steps f to g Back to the handheld terminal (APP);

k. In order to avoid the influence of random noise and the like on the nuclear magnetic resonance signal, repeat step j to carry out superposition testing on the nuclear magnetic resonance, with less noise influence;

l. On the hand-held terminal (APP), the magnetic resonance signals obtained in steps j and k are digitally filtered, spectrum transformed, etc. to further denoise the signals, and then the processed relaxation signals of a certain layer in front of the test are combined with Comparing the theoretical signals when the grain is completely stored, so as to obtain the accurate grain storage situation at a certain depth;

m. According to the preset detection parameters, the direct current is kept constant, the power regulator adjusts the alternating current to the next set value, and the operation of steps j-l is repeated, so as to realize the determination of grain storage conditions at different depths;

n. After the overall detection is completed, the reserves of each layer depth are completely drawn on a cloud map. At this time, the complete detection process of the measuring point is completed;

o. If it is necessary to detect the grain storage situation in other locations, after re-arranging the universal rotating coil, repeat steps d-n;

p. After all the measurements are completed, the handheld terminal APP generates a detailed report of the detection, so as to obtain the actual grain storage situation inside the granary.

See Figure 4 for the measurement range of the magnetic field weakening sensor array; the magnetic field weakening sensor array and excitation coil are arranged on the coil support;

The magnetic field weakening sensor array 4 is symmetrically fixed on the diagonal of the coil support 5 for detecting magnetic signals;

Among them, the detection range 28 to which the first magnetic sensor 21 belongs, the detection range 29 to which the second magnetic sensor 22 belongs, the detection range 30 to which the third magnetic sensor 23 belongs, and the detection range 31 to which the fourth magnetic sensor 24 belongs. The covering method satisfies the requirement that the detection interval covers the entire range covered by the excitation coil 6 .

A non-invasive nuclear magnetic resonance grain storage volume detection device and detection method proposed by the present invention can clearly show the storage situation inside the granary without opening the granary, so as to meet the requirements of sampling the granary during the inspection of the granary The needs of the investigation; the detection device adopts the design structure of the universal rotating coil, the handheld terminal (APP), and the distributed detection device, which reduces the workload of laying the coil when the detection location is frequently changed to a certain extent, and improves the detection efficiency; the designed The weak magnetic sensor array solution enhances the precise imaging capability of the granary, and has the advantages of accurate detection results and multi-dimensional imaging; the detection method ranges from preliminary judgment of whether there is adulteration to accurate provision of grain distribution maps, which not only improves detection efficiency, but also enables accurate detection Obtain the detection results; the handheld terminal (APP) used can obtain the grain distribution cloud map of the granary in real time, which has guiding significance for the arrangement of the granary inspection work;

A non-invasive nuclear magnetic resonance grain storage volume detection device and detection method proposed by the present invention have the characteristics of accurate detection results, fast detection speed, safety and environmental protection, and solve the problem of the inability to actually survey the actual storage conditions inside the granary during the inspection process of the traditional granary problem, the present invention will lay an important foundation for my country's grain management and grain storage industries, and has good promotional prospects and promotional value.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (2)

1. A method of non-invasive nuclear magnetic resonance grain bin reserve detection, wherein a non-invasive nuclear magnetic resonance grain bin reserve detection apparatus is employed, the apparatus comprising:

the handheld terminal adopts a wireless transmission communication mode and is used for configuring the working state and parameters of the detection device, recovering the acquired magnetic resonance signal data, decompressing and analyzing the magnetic resonance signals acquired during granary detection in real time through a built-in data analysis algorithm, and generating a grain distribution cloud picture and a detection report;

the exciting coil is used for carrying the generated direct current and alternating current and exciting nuclear magnetic resonance signals of moisture in grains;

a weak magnetic sensor array for collecting nuclear magnetic resonance signals of moisture in grains;

the universal rotating bracket is used for supporting the weak magnetic sensor array and realizing detection in any direction in the granary;

the main detection device is used for realizing nuclear magnetic resonance signal excitation of moisture in grains by generating direct current and random waveform alternating current to the excitation coil, collecting and returning magnetic resonance signals to the handheld terminal for analysis by connecting with the weak magnetic sensor array;

the weak magnetic sensor array includes:

the magnetic sensors are fixed at different positions of the universal rotary support, are connected with an original signal acquisition module in the main detection device through data transmission lines and are used for acquiring weak magnetic signals;

the magnetic sensor detection module is connected with the magnetic sensor, monitors the state of the magnetic sensor in real time, and actively alarms and reminds when the magnetic sensor is abnormal;

the universal rotating support comprises a triangular support, a universal rotating head and a coil support, wherein:

the triangular bracket is connected with the universal swivel and used for supporting the coil bracket to keep a certain fixed direction;

the universal rotating head is directly connected with the coil bracket and realizes detection in different directions by rotating to any angle;

a coil support for fixing the coil shape and the weak magnetic sensor array;

the coil support is of a square structure, and four magnetic sensors are symmetrically arranged on diagonal lines of the square structure;

the main detection device includes:

the wireless communication controller is communicated with the handheld terminal, receives parameter configuration and returns compressed magnetic resonance signal data; in addition, the detection device is connected with the master controller to control the operation of the detection device;

the master controller controls the generation of direct current according to the set detection time sequence;

the main detection device further includes:

the high-power supply is connected with the impedance adjuster to provide energy for the output of direct current;

the impedance regulator is connected with the exciting coil and is used for controllably inputting the energy of the high-power supply to the exciting coil so as to generate the required direct current;

an arbitrary wave generator controlled by the master controller and generating alternating current signals with different waveforms and different frequencies;

the power amplifier is connected with the power regulator, the power regulator is controlled by the overall controller, and outputs alternating current, and any wave alternating current signal is generated by amplification of the power amplifier;

the direct current-alternating current isolation module is arranged between the power amplifier and the exciting coil, so that mutual crosstalk between direct current and alternating current is avoided, and only the generated direct current and alternating current act on the exciting coil;

the basic power supply provides power required by the wireless communication controller, the master controller, the arbitrary wave generator, the power amplifier and the power regulator, thereby ensuring the normal operation of the detection device;

the main detection device further includes:

the original signal acquisition module is connected with the weak magnetic sensor array and used for collecting magnetic resonance signals acquired by each magnetic sensor;

the data is stored locally and is connected with the original signal acquisition module, and the acquired signal data is stored locally for subsequent data processing and verification;

the data compression module is connected with the data local storage, transmits the compressed data to the wireless communication controller, and further transmits the compressed data to the handheld terminal, so that a detection result is obtained on site;

the method comprises the following steps:

step 1, selecting a detection position, fixing the direction of a coil, and connecting a detection device;

step 2, starting up the granary reserve detection device for self-checking;

step 3, calculating the size of the impedance regulator according to the actual detection requirement, adjusting the output size of direct current, and setting other detection parameters by the handheld terminal;

step 4, judging whether the data of the handheld terminal and the detection device can be transmitted to each other normally, if the data cannot be communicated normally, checking the handheld terminal and the detection device respectively, and re-checking;

step 5, each weak magnetic sensor in the weak magnetic sensor array starts to continuously collect signals in a detection range, direct current detection is started, and after direct current excitation is finished, a hard turn-off mode is adopted, and the weak magnetic sensor array collects nuclear magnetic resonance signals at different positions;

step 6, the data local storage module firstly stores the signals detected by the weak magnetic sensor for rechecking the follow-up experimental results, and then sends the detected signals to the handheld terminal through the wireless communication sensor;

step 7, setting a data reconstruction algorithm in the handheld terminal, and restoring and representing the signals transmitted to the handheld terminal to obtain original data information;

step 8, after the original data is restored, the built-in algorithm of the handheld terminal further carries out noise elimination processing on the signals through digital filtering and spectrum conversion means, then the processed relaxation signals are compared with theoretical signals when grains are completely stored, when the detected relaxation signals are different from the theoretical signals, the detected relaxation signals are considered to have adulteration possibility, and when the detected relaxation signals are identical to the theoretical signals or are within an error allowable range, the detected relaxation signals are considered to have no adulteration phenomenon;

step 9, if the detection position of the granary is not adulterated, rotating or moving the universal rotary support to detect other positions; if the preliminary analysis result shows that the detection position is abnormal, starting subsequent direct current and alternating current combined detection, and carrying out detailed detection on the front layering to be detected, thereby further analyzing the abnormal situation of the granary;

step 10, starting direct current excitation, enhancing the magnetic resonance signal intensity of grains, rapidly exciting by using alternating current after direct current is turned off, collecting nuclear magnetic resonance signals at different positions by an array magnetic sensor, compressing data at the moment and transmitting the compressed data back to a handheld terminal through the steps 6 to 7;

step 11, in order to avoid the influence of random noise on nuclear magnetic resonance signals, the step 10 is repeated to carry out superposition test on nuclear magnetic resonance, so that the noise influence is reduced;

step 12, carrying out digital filtering and frequency spectrum transformation on the magnetic resonance signals obtained in the steps 10 and 11 on the handheld terminal to further carry out noise elimination processing on the signals, and then comparing a certain layer of processed relaxation signals in front of the to-be-detected with theoretical signals when grains are completely stored, so as to obtain the accurate grain storage condition of a certain layer depth;

step 13, according to preset detection parameters, the direct current is kept constant, the power regulator regulates the alternating current to the next set value, and the operations of the steps 10-12 are repeated, so that the grain storage conditions of different depths are judged;

14, after the whole detection is completed, the reserves of each layer depth are completely drawn on a cloud picture, and at the moment, the complete detection process of the detection position is completed;

step 15, if the grain storage condition at other positions is detected, repeating the steps 4-14 after the universal rotating coil is rearranged;

and step 16, after all the measurements are finished, the handheld terminal generates a detailed report of detection to obtain the actual grain storage condition in the granary.

2. The method of claim 1, wherein the device generates a dc voltage of 50-200A for a duration of 5s, a ac voltage of 0.05A-10A for a duration of 40ms; the weak magnetic sensor array continuously collects.

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