A testing device, method and system for farmland road surface spectrum

Abstract

The present invention discloses a testing device, a testing method and a system for a farmland pavement spectrum, and belongs to the field of agricultural field soil pavement spectrum testing. The farmland pavement spectrum testing device includes: a laser displacement sensor, a sensor protection device, a multi-channel data acquisition system and acquisition software and a host computer. The testing method includes: using a non-contact measurement laser displacement sensor to measure the elevation (displacement) changes of the four wheel positions and the vertical elevation changes of the center of mass of the whole machine, using MATLAB to calculate the average value and standard deviation of the elevation data, and obtaining the weight coefficients of each wheel and the center of mass through the coefficient of variation method, and taking the weighted average value as the elevation result of the whole machine, and performing a discrete Fourier transform on the weighted elevation data to obtain the farmland pavement spectrum. The above technical scheme has no additional mass for the test system, has little effect on the stiffness and damping of the system, is suitable for the harsh environment of complex farmland opening, has high test accuracy and efficiency, and is easy to operate.

Description

Technical Field

[0001] The present invention relates to the field of agricultural field soil pavement spectrum testing, and further to a testing technology for the excitation spectrum of farmland pavement on which agricultural tractors / harvesters in agricultural machinery equipment travel, and specifically to a testing device, method and system for the farmland pavement spectrum. Background Art

[0002] As one of the main excitation sources of agricultural machinery, the unevenness of farmland roads leads to large random excitation and severe vibration when agricultural machinery is working in the field. On the one hand, it affects the power, driving quality and road dynamic load of agricultural machinery, and may shorten the service life of agricultural machinery, which is not conducive to agricultural production. On the other hand, it directly affects the driving smoothness and driving comfort of agricultural machinery, and affects the physical and mental health of the driver.

[0003] As a way to describe the excitation of farmland pavement, the farmland pavement spectrum is one of the excitation (input) conditions for agricultural machinery vibration modeling and control, and is also the basis for obtaining the vibration characteristics of agricultural machinery. Accurately obtaining the excitation of farmland pavement directly affects the analysis results of the dynamic characteristics of agricultural machinery, and thus affects the vibration control and dynamic design of agricultural machinery.

[0004] Among the road vehicle unevenness test methods, traditional direct contact methods such as light, ruler, straight beam, and multi-wheel leveling vehicles are often used. The problems are large drift of each test result and low test accuracy. The laser cross-section method based on inertial reference is affected by the cleanliness of the road surface and the vehicle speed, resulting in poor test accuracy. Furthermore, standard pavement methods such as conventional cement and asphalt are not fully applicable to complex and open farmland soil environments.

[0005] At present, the acquisition of farmland road surface spectrum generally uses GPS to select a certain point of agricultural machinery as a reference, and measures the elevation change of the reference point as the elevation change data of the whole machine, or uses the five-wheel instrument method to measure the elevation change of one wheel as the elevation change data of the whole machine. This test method uses a straight line composed of points to replace the unevenness of the field road surface where the agricultural machinery has traveled, which has problems such as low repeatability of test results and poor test accuracy.

[0006] At present, the testing equipment for farmland road surface spectrum based on five-wheel instrument, GPS, etc. is relatively complex, and is greatly affected by dust and other factors in the complex farmland environment. Summary of the invention

[0007] The present invention aims to address the technical defects of the prior art and provide a testing device, a testing method and a system for farmland pavement spectrum, so as to solve the technical problems of conventional testing devices and testing methods such as low accuracy, poor precision, complex structure and great influence by the environment.

[0008] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0009] A method for testing a farmland road surface spectrum, the method uses laser displacement sensors fixed on the front and rear axles and the center of mass of agricultural machinery to measure the distance between the front and rear axles and the center of mass and the ground, record the road elevation change data, transmit the data to a dynamic test collector through a test wire, and display the data in a test computer. The test method can be used as a method for testing the unevenness of farmland road surfaces and obtaining road surface spectra for four-wheeled agricultural machinery with axles, and is suitable for agricultural machinery without a vibration reduction system.

[0010] Preferably, in the method, when the agricultural machinery is operating in the field, the changes in the elevation of the road surface at the four wheels and the center of mass are measured simultaneously.

[0011] As a preferred method, the method uses a laser displacement sensor to measure the elevation change of the agricultural machinery road surface, which is a non-contact measurement method. Laser has good monochromaticity, directionality, and focusability (penetration) over time and space, and has significant advantages in measurement accuracy and measurement range, especially in the complex dusty working environment of the farmland, it can still maintain normal use.

[0012] Preferably, the method uses four laser displacement sensors fixed on the front and rear axles to measure the displacement of the front and rear axles relative to the road surface, instead of the elevation change of the front and rear wheels relative to the road surface.

[0013] Preferably, in this method, the laser displacement sensor is installed at the intersection of the horizontal axis and the vertical axis where the centroid is located on the chassis of the agricultural machinery (for the convenience of measuring vertical elevation changes and installation).

[0014] Preferably, the method measures the elevation change of the road surface at the four wheels and the center of mass at the same time, and calculates the weighted average of the measured elevation change data of the road surface at the four wheels and the center of mass as the elevation change data of the road surface of the whole vehicle;

[0015] The method comprises the following steps:

[0016] Step S1: Install the laser displacement sensor and its protective device on the front and rear axles close to the four wheels, and install the fifth sensor at the intersection of the horizontal axis, the longitudinal axis and the chassis of the agricultural machinery;

[0017] The vehicle-mounted DC power supply is used to power the test acquisition instruments and sensors in the entire test system. An insulated thick copper wire is selected, one end of which is connected to the positive and negative poles of a 12V battery, and the other end is connected to a sine wave inverter to convert 12V DC power into 220V AC power. The multi-channel dynamic signal acquisition instrument is powered by a power adapter, and the 12V DC power supply is used to power the laser displacement sensor through a 0-4mA constant current source current modulation module.

[0018] In order to increase the power focusing and anti-interference of the laser sensor, the driving circuit of the laser sensor generally adopts a transistor drive or an inverter drive mode. The present invention adopts two power transistors in parallel to enhance the driving power, increase the laser bright spot, improve the anti-interference performance, and make the circuit more stable. Figure 7 As shown, the circuit is driven by a 1mA constant current.

[0019] Place the agricultural machinery at the starting point of the test field, adjust the laser displacement sensor to 0, set the current laser displacement sensor elevation from the ground as the test system reference point, and determine the relative zero point of the test system;

[0020] Step S2: The agricultural machinery is operated and slowly accelerated to ensure that the vehicle speed is maintained at 10 km / h before entering the test road surface. The length of the test road surface is selected to be 300 m. Multiple 300 m test roads are selected in the same test field for testing to avoid soil compaction on one test road.

[0021] Step S3: Based on the soil elevation data x1, x2, x3…x measured by each laser displacement sensor n , calculate its mean and standard deviation, mean Standard Deviation Define the ratio of the mean value of road roughness to the standard deviation as the coefficient of variation, and calculate the coefficient of variation for each wheel as According to the changes in the elevation data of the four wheels and the center of mass, the weight factor of the farmland road roughness is determined as follows: The elevation data changes obtained at each wheel position and the elevation change values ​​at the center of mass position are X1, X2, X3, X4 and X5; further, the roughness change value of the farmland road surface is obtained using the weighted average method. (It can effectively reduce the randomness of the test results of a single wheel and the problem of poor repeatability of the test results);

[0022] Then, all the data collected from multiple tests are weighted averaged, and several groups (preferably 6 groups) of test data are randomly selected to calculate their average value as the final test data (to reduce the impact of randomness).

[0023] Preferably, the coefficient of variation method is used to obtain the weight factors of each wheel and the center of mass, and the weighted average of the elevation change data is calculated according to the weight factors.

[0024] On the basis of the above technical solution, the present invention further provides a testing device for implementing the above testing method, which includes a laser displacement sensor, a sensor protection device, a multi-channel data acquisition system, acquisition software, and a host computer.

[0025] Preferably, the sensor protection device is installed on both sides of the sensor, and the sensor protection device includes two chucks and protective covers, wherein one chuck is fixed on the front and rear axles of the agricultural machinery close to the wheels, and the sensor is installed in the protective cover, the protective cover is installed on the front and rear axles, and the other chuck is clamped close to the protective cover to fix and protect the laser displacement sensor.

[0026] Preferably, the bottom of the sensor protection device is a transparent acrylic plate (preferably with a thickness of 2 mm); to ensure that the laser beam can be emitted and received, while effectively preventing interference from factors such as dust.

[0027] On the basis of the above technical scheme, the present invention further provides a test system for implementing the above test method, in which there is a sensor power supply system, wherein the sensor power supply system converts the vehicle-mounted 12V power supply into 220V AC power by using a sine wave inverter, and then powers the multi-channel data acquisition instrument and the sensor respectively through a power adapter and a constant current source conditioning module. The whole machine operating speed of the test system can reach 30km / h, and the operating temperature can work between -40℃ and 80℃, which is suitable for normal operation in the temperature and humidity environment of open and complex farmland operations.

[0028] The present invention discloses a testing device, a testing method and a system for a farmland road surface spectrum, which are used to solve the problems of the prior art that the method of measuring the unevenness of the road surface by the elevation change of the whole machine is often used, and the test results are low in accuracy, greatly affected by the traction speed, dust and crops in the farmland, etc. The farmland road surface spectrum testing device includes: a laser displacement sensor, a sensor protection device, a multi-channel data acquisition system and acquisition software and a host computer. The testing method includes: using a non-contact measurement laser displacement sensor to measure the elevation (displacement) changes of the four wheel positions and the vertical elevation changes of the center of mass of the whole machine, using MATLAB to calculate the average value and standard deviation of the elevation data, obtaining the weight coefficients of each wheel and the center of mass by the coefficient of variation method, and taking the weighted average value as the elevation result of the whole machine, and performing discrete Fourier transformation on the weighted elevation data to obtain the farmland road surface spectrum. The present invention is an accurate and referenceable testing technology suitable for agricultural machinery. The above technical scheme has no additional mass for the test system, has little effect on the stiffness and damping of the system, is suitable for the harsh environment of complex farmland opening, has high test accuracy and efficiency, and is easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is the farmland pavement spectrum test system device, test method and system flow chart;

[0030] Figure 2 This is the installation diagram of the farmland pavement spectrum testing system;

[0031] Figure 3This is a schematic diagram of the installation and protection device of the non-contact laser displacement sensor;

[0032] Figure 4 This is a simplified diagram of the sensor protection system in the test system;

[0033] Figure 5 Provide power supply technology for the test system's collectors and sensors;

[0034] Figure 6 This is a working diagram of the laser displacement sensor;

[0035] Figure 7 It is the transmitting and receiving circuit diagram of the laser displacement sensor;

[0036] Figure 8 It is a flow chart of the farmland pavement spectrum testing system based on non-contact testing;

[0037] Fig. 9 It is the curve diagram of farmland road elevation (roughness);

[0038] Fig.10 is the power spectrum of farmland pavement;

[0039] Fig.11 It is a system for real-time display of farmland road elevation data and acquisition of farmland road spectrum;

[0040] In the figure:

[0041] 1. Laser displacement sensor 2. Sensor protection device 3. Test lead

[0042] 4. Dynamic test acquisition instrument 5. Host computer 6. Bridge

[0043] 7. Wheel 8. Chuck 9. Transparent protective cover

[0044] 10. Front and rear axle placement 11. Sensor placement 12. Laser emission area

[0045] 13. Signal receiving area. DETAILED DESCRIPTION

[0046] The specific embodiments of the present invention will be described in detail below. In order to avoid too much unnecessary details, the well-known structures or functions will not be described in detail in the following examples. The approximate language used in the following examples can be used for quantitative expression, indicating that the quantity can be allowed to have a certain change without changing the basic function. Unless otherwise defined, the technical and scientific terms used in the following examples have the same meaning as those generally understood by those skilled in the art to which the present invention belongs.

[0047] Example 1

[0048] By measuring the elevation changes of the four wheels and the center of mass at the same time and taking the weighted average and MATLAB data analysis method, the pavement spectral power density of the farmland road can be accurately obtained, providing a reference and basis for agricultural machinery vibration reduction and product development and design.

[0049] To achieve the above-mentioned purpose, the present invention provides a test technology solution for recording elevation changes with a laser displacement sensor, a software data analysis method and result analysis.

[0050] To achieve the above objectives, a test technology scheme for a farmland road surface excitation test method and a collection system suitable for tractors is proposed. The specific steps are as follows:

[0051] Step 1 determines the location of the agricultural machinery road excitation measurement point, that is, determines the installation location of the laser displacement sensor. Since the agricultural machinery is in working condition, it is impossible to fix the laser displacement sensor to obtain the wheel elevation change. Considering that the front and rear axles are rigidly connected to the wheels and there is no relative displacement, the elevation change of the front axle replaces the elevation change of the front two wheels, and the elevation change of the rear axle replaces the elevation change of the rear two wheels. At the same time, to ensure the accuracy of the elevation data acquisition, the laser displacement sensor and its protection device are installed on the front and rear axles close to the four wheels (such as Figure 3 ).

[0052] Taking into account the measurement of vertical elevation changes of agricultural machinery, the vertical center of mass position has no effect on the measurement. At the same time, for the convenience of installation, the installation position of the fifth laser displacement sensor is determined at the intersection of the horizontal axis and the vertical axis center of mass at the chassis of the agricultural machinery.

[0053] The mass center position is determined by the mass reaction method. The four measuring platforms are placed under the four wheels respectively, and the mass data obtained by the four measuring platform units are M1, M2, M3, and M4, respectively. l is the wheelbase of the wheel vehicle, and b is f is the front wheelbase of the vehicle, b r It is the rear wheelbase of the vehicle.

[0054] According to the torque balance principle, we have:

[0055]

[0056] The centroid of the horizontal axis is thus:

[0057]

[0058] Take the distance from the center of mass to the longitudinal center of mass plane of the vehicle as y. According to the moment balance principle, we have:

[0059]

[0060] The vertical axis centroid is thus:

[0061]

[0062] Step 2 Install the laser displacement sensor and its protective device. First, fix the laser displacement sensor (W20mm×H44mm×D25mm) in the protective device (the bottom surface uses a transparent acrylic plate to ensure that the laser emission and reception are not interfered with, and can also prevent dust interference) (such as Figure 4 ), then place the guards on the front and rear axles 50 mm away from the wheels, install the chucks on the outside of the guards and secure them.

[0063] Step 3: Connect the data acquisition equipment. After fixing the laser displacement sensor and the protective device at the determined measuring point, the data is transmitted to the dynamic test acquisition instrument located in the cab through the test wire connected to the sensor. In order to reduce the interference of wire shaking on the data during signal transmission, the wire is tightly attached to the agricultural machinery frame with insulating tape.

[0064] Place the dynamic test collector and the test computer in the cab to prevent them from falling due to vibration during vehicle operation. Then connect the test wire to the dynamic test collector. Finally, connect the dynamic test collector and the test computer to obtain the road elevation data through the test computer.

[0065] Use two insulated thick copper wires, connect one end to the positive and negative poles of the 12V vehicle power supply (battery), and the other end to the positive and negative poles of the sine wave inverter to convert 12V DC into 220V AC.

[0066] The sine wave inverter converts it into 220V AC power, which is then used to power the laser displacement sensor through a 0-4mA constant current source current regulation module.

[0067] The sine wave inverter converts it into 220V AC power, which is then used to power the multi-channel dynamic signal acquisition instrument (such as Figure 5 ).

[0068] Step 4 is to conduct a preliminary test. After the installation of the measuring equipment is completed, a feasibility test is first conducted on the current road surface. The laser displacement sensor emits a strong laser beam to the ground, and the light signal is reflected by the ground and transmitted back to the receiving area (the principle is as follows Figure 6 , circuit such as Figure 7 ) to ensure that the laser displacement sensor can measure data and prevent the situation where data cannot be collected due to improper connection.

[0069] Step 5: Set the test system reference point. Place the agricultural machinery at the starting point of the test field, adjust the laser displacement sensor reading to 0, and set the current laser displacement sensor elevation from the ground as the test system reference point, that is, the relative zero point of this test system.

[0070] Step 6: Set system parameters. Set the test data name and save path on the test computer, and set the basic parameters and trigger conditions of each test channel.

[0071] Step 7: Start the test. Start the agricultural machinery and accelerate slowly, ensuring that the speed is maintained at 10 km / h before entering the test road. The length of the test road is 300 m. Multiple 300 m test roads are selected in the same test field for testing to avoid soil compaction on one test road, which may cause errors.

[0072] Step 8: Get real-time data. When the agricultural machinery enters the test starting point, click on data collection in the system corresponding to the host computer and the dynamic data collector, and click on end when the agricultural machinery leaves the test area. The data collected by the dynamic data collector is saved through the matching test software in the host computer.

[0073] Step 9: Data processing: The acquired data is exported according to the elevation change data of each wheel and the center of mass, and the standard deviation and average value of the elevation change data of each wheel are calculated.

[0074] Step 10: Weighted calculation. The coefficient of variation of each wheel is obtained by using the coefficient of variation method. The weight factor of each wheel and the center of mass is obtained from the coefficient of variation. The weighted average of the road elevation change data of the four wheels and the center of mass is taken as the elevation change data of the whole machine. The specific calculation is as follows:

[0075] average value

[0076] Standard Deviation

[0077] Coefficient of variation

[0078] Weight Factor

[0079] Weighted average

[0080] Among them, X1, X2, X3, and X4 represent the data collected by the four wheels, that is, X1 = x1 + x2 + x3 + ... + x n , X5 represents the data collected at the centroid.

[0081] Step 11 performs weighted average processing on all data collected from multiple tests, randomly selects 6 groups of test data, and calculates their average value as the final test data to reduce the impact of randomness.

[0082] Step 12: The data is subjected to discrete Fourier transform to obtain the power spectrum of the data in the frequency domain. The power spectrum density formula G is determined by considering the power spectrum obtained after Fourier transform and the influence of speed through the general expression of power spectrum density. a (n).

[0083] Step 13 is to input a program for generating a road surface spectrum through software, obtain a road surface roughness curve, and a road surface power spectrum density diagram, and then compare them with the road surface grade in the national standard to determine the farmland road surface grade.

[0084] Step 14: Write a program based on the above formula to design a real-time display system for farmland road elevation data and a farmland road surface spectrum acquisition system to achieve the real-time acquisition function of road surface roughness data (such as Fig.11 ).

[0085] Example 2

[0086] A testing device, a testing method and a system for a farmland road surface spectrum include five laser displacement sensors, four detachable sensor protection devices, a dynamic test acquisition instrument, a host computer and a plurality of test leads. Figure 1 The test system shown is installed on the front and rear axles of the whole machine. The laser displacement sensor 1 is placed in the sensor protection device 2. Removable protective covers are installed on both sides of the sensor to form a sensor protection device to prevent the sensor from vibrating off or being rolled into the wheel during the movement of the agricultural machinery. The sensor protection device is fixed to the front and rear axles of the agricultural machinery at a distance of 50 mm from the wheel through a chuck device. The bottom of the device is a transparent acrylic plate (thickness of 2 mm) to ensure that the laser beam can be emitted and received while reducing the impact of dust on the sensor. The fifth laser displacement sensor is installed at the intersection of the horizontal axis and the vertical axis, and the center of mass is located at the chassis of the agricultural machinery. Five test wires 3 connected to the laser displacement sensor are attached to the chassis of the machine through the body into the cab and connected to the dynamic test collector 4, and then connected to the host computer 5 through wires, and the data is read through the test software in the host computer that is matched with the dynamic test collector.

[0087] After the agricultural machinery enters the test farmland, the initial height at the test starting point is set as the relative reference point of the laser displacement sensor, and the parameters such as the data saving name and path, sensor sensitivity, and data acquisition trigger conditions are set. Then the vehicle speed is increased and maintained at 10km / h to enter the test section. After entering the test starting point, click on data collection. The laser displacement sensor emits laser light to the ground of the farmland being tested. The laser is reflected by the ground of the farmland being tested and captured by the receiver. After being captured, the light beam is converted into an electrical signal and transmitted to the dynamic collector. The dynamic collector begins to collect road elevation change data and transmits it to the host computer. When the agricultural machinery completes data collection once, it stops to view and store the data, and then enters the next test road to repeat the above steps.

[0088] Select multiple test routes for testing, perform weighted average calculation on all collected data, randomly select six groups of test data and take their average value as test data to reduce the impact of chance on the test. (The weighted average value of the calculated elevation change data is processed using the Fourier transform method to obtain the power spectrum of the data in the frequency domain. The discrete Fourier transform formula is:

[0089]

[0090] Where: X(k) is discrete Fourier transform, k = 0, 1, 2, ..., N-1; x(n) is sampled data, n = 0, 1, 2..., N-1; N is the number of sampling points.

[0091] The roughness of the road surface is generally characterized and described by the road surface power spectrum density function, which is expressed as:

[0092]

[0093] Where: n is the spatial frequency; n0 is the reference spatial frequency, generally 0.1; G a (n0) is the road surface power spectrum density value corresponding to the reference spatial frequency; G a (n) is the random road surface power spectrum density corresponding to n, and the frequency index of the graded road surface spectrum is W=2.

[0094] Considering the power spectrum after Fourier transform, the formula for the road surface power spectrum density is:

[0095]

[0096] Where: ΔL is the sampling distance interval, and its value is ΔL=L / N=Tu / N=u / f, T is the sampling time, u is the vehicle speed, and f is the sampling frequency.

[0097] Considering the vehicle speed at the same time, the road power spectrum density formula is obtained as follows:

[0098]

[0099] The program that generates the road surface spectrum is input into the software to obtain the road surface roughness curve and the road surface power spectrum density diagram, that is, the farmland road surface spectrum. The farmland road surface grade is determined by comparing it with the road surface grade in the national standard.

[0100] In summary, the present invention measures the elevation changes of the front and rear axles and the center of mass instead of the elevation changes of the whole machine, and obtains the weight factor through the coefficient of variation method, performs weighted average calculation on it, and uses the result as the excitation of the whole machine to obtain a more accurate agricultural machinery road surface excitation input. The method is simple to operate and is convenient for experimenters to analyze different farmland road surface excitations.

[0101] The embodiments of the present invention are described in detail above, but the contents are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the scope of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for testing farmland pavement spectrum, characterized in that: The method uses laser displacement sensors fixed on the front and rear axles and the center of mass of agricultural machinery to measure the distance between the front and rear axles and the center of mass and the ground, record the road elevation change data, transmit the data to the dynamic test collector through the test wire, and display the data in the test computer; The method measures the elevation change of the road surface at the four wheels and the center of mass at the same time, and calculates the weighted average value of the measured elevation change data of the road surface at the four wheels and the center of mass as the elevation change data of the road surface of the whole vehicle; The method comprises the following steps: Step S1: Install the laser displacement sensor and its protective device on the front and rear axles close to the four wheels, and install the fifth sensor at the intersection of the horizontal axis, the longitudinal axis and the chassis of the agricultural machinery; The vehicle-mounted DC power supply is used to power the test acquisition instruments and sensors in the entire test system. An insulated thick copper wire is selected, one end of which is connected to the positive and negative poles of a 12V battery, and the other end is connected to a sine wave inverter to convert 12V DC power into 220V AC power. The multi-channel dynamic signal acquisition instrument is powered by a power adapter, and the 12V DC power supply is used to power the laser displacement sensor through a 0-4mA constant current source current modulation module. Place the agricultural machinery at the starting point of the test field, adjust the laser displacement sensor to 0, set the current laser displacement sensor elevation from the ground as the test system reference point, and determine the relative zero point of the test system; Step S2: The agricultural machinery is operated and slowly accelerated to ensure that the vehicle speed is maintained at 10 km / h before entering the test road surface. The length of the test road surface is selected to be 300 m. Multiple 300 m test roads are selected in the same test field for testing to avoid soil compaction on one test road. Step S3: Based on the soil elevation data x1, x2, x3…x measured by each laser displacement sensor n , calculate its mean and standard deviation, mean Standard Deviation Define the ratio of the mean value of road roughness to the standard deviation as the coefficient of variation, and calculate the coefficient of variation for each wheel as According to the changes in the elevation data of the four wheels and the center of mass, the weight factor of the farmland road roughness is determined as follows: The elevation data changes obtained at each wheel position and the elevation change values ​​at the center of mass position are X1, X2, X3, X4 and X5; further, the roughness change value of the farmland road surface is obtained using the weighted average method. Then all the data collected from multiple tests are weighted averaged, and several groups of test data are randomly selected to calculate their average value as the final test data.

2. The method for testing the farmland road surface spectrum according to claim 1, characterized in that: The coefficient of variation method is used to obtain the weight factors of each wheel and the center of mass, and the weighted average of the elevation change data is calculated according to the weight factors.

3. The method for testing the farmland pavement spectrum according to claim 1, characterized in that: The testing device includes a laser displacement sensor, a sensor protection device, a multi-channel data acquisition system, acquisition software, and a host computer.

4. The method for testing the farmland road surface spectrum according to claim 3, characterized in that: The sensor protection device is installed on both sides of the sensor. The sensor protection device includes two chucks and protective covers, wherein one chuck is fixed on the front and rear axles of the agricultural machinery close to the wheels, and the sensor is installed in the protective cover, the protective cover is installed on the front and rear axles, and the other chuck is clamped close to the protective cover to fix and protect the laser displacement sensor.

5. The method for testing farmland pavement spectrum according to claim 1, characterized in that: The test system has a sensor power supply system, which is characterized in that the sensor power supply system uses a sine wave inverter to convert the vehicle-mounted 12V power supply into 220V AC power, and then powers the multi-channel data acquisition instrument and the sensor respectively through a power adapter and a constant current source conditioning module.

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