Device and method for measuring land flatness

Abstract

The invention discloses a device for measuring land flatness, comprising an adjustable leveling tripod and a base plate, a support frame and an RTK module are fixed on the base plate, a top plate is fixed on the top of the support frame, a vertical rotating shaft is rotatably penetrated in the top plate, a driving mechanism for driving the rotating shaft to rotate is provided on the top plate, two first connecting members are fixed on the rotating shaft at the upper end of the top plate, and the first connecting member is detachably fixed with a cross bar with an adjustable length perpendicular to the rotating shaft, a sliding mounting member is detachably fixedly installed on the cross bar, a laser radar scanner is detachably fixedly installed on the sliding mounting member, a counterweight rod is detachably fixedly installed on the other first connecting member, and a counterweight block is detachably fixedly provided on the counterweight rod. The measurement method using the device can quickly obtain multiple circular terrain DEM models, and perform overlapping part fitting to obtain an accurate land flatness DEM model, thereby solving the difficulty of laser radar scanners in measuring farmland flatness.

Description

Technical Field

[0001] The invention relates to the technical field of field flatness measurement, and in particular to a device and a method for measuring land flatness. Background Art

[0002] After the farmland is plowed, it is necessary to use a grader to flatten the farmland and perform leveling operations. In order to ensure the flatness of the field, it is necessary to use appropriate equipment and tools to test it after leveling, which can not only verify the leveling effect, but also provide feedback to the grader operation.

[0003] The flatness of fields could only be detected by visual inspection at first. Visual inspection could not detect slow changes in slope, so depressions and peaks were likely to appear after irrigation. Later, it gradually developed to the use of total stations for grid point detection, which could solve the problem of large-scale flatness of farmland. Later, with the development of remote sensing technology, the use of lidar scanners to survey field flatness has gradually become mainstream.

[0004] The difficulty in limiting the use of LiDAR scanners in fields is that farmland is different from factory buildings. There are no large rails above the farmland to translate the LiDAR scanner. In order to solve this problem, for example, the following is disclosed in Chinese patent documents:

[0005] “A surface roughness measurement system and method”, its publication number is CN102706295B, and the authorization announcement date is November 5, 2014.

[0006] "Farmland Surface Flatness Measurement System and Measurement Method", its publication number is CN109000596B, and the authorization announcement date is January 10, 2020.

[0007] "A device and method for automatic measurement of surface roughness", its publication number is CN114777690B, and the authorization announcement date is August 15, 2023.

[0008] These three patent documents all disclose a similar bracket to measure the flatness of farmland. The principle is to slide the measuring tool on the bracket, scan the field below in a linear sliding manner, and attach a corresponding scanning data processing method. However, this bracket and measurement method can only support the measurement of a short straight line of farmland. The single measurement range is small. If you want to measure all the farmland, you need to move the bracket continuously, which is time-consuming and labor-intensive.

[0009] The publication number of "A dynamic paddy field flatness detection device and method based on laser ranging" is CN104359430B, and the authorization announcement date is July 11, 2017. It discloses a laser ranging method and dynamic error correction method that can be mounted on a mobile vehicle. This method can quickly move the laser radar scanner, but when the field flatness is poor, the vehicle bumps too much during movement, and the reliability of the results obtained through data correction is not high.

[0010] In view of this, it is necessary to redesign a device for measuring land flatness and a related measuring method. Summary of the invention

[0011] The purpose of the present invention is to provide a device and a method for measuring the flatness of land, to solve the problem of too small a reciprocating straight line measurement area by designing a circular measurement area, to solve the problem of poor reliability of mobile vehicle data correction by obtaining non-bumpy and stable lidar scanner data, so as to solve the problems described in the background technology.

[0012] The technical solution of the present invention is achieved in this way:

[0013] A device for measuring land flatness comprises an adjustable leveling tripod, a bottom plate is detachably fixedly provided on the top of the adjustable leveling tripod, a support frame and an RTK module are fixedly provided on the upper end of the bottom plate, a top plate is fixedly provided on the top of the support frame, a vertically arranged rotating shaft is rotatably passed through the top plate, a driving mechanism for driving the rotating shaft to rotate is also provided on the top plate, two first connecting members symmetrically arranged around the central axis of the rotating shaft are fixedly provided on the rotating shaft at the upper end of the top plate, a cross bar with an adjustable length perpendicular to the rotating shaft is detachably fixedly provided on one of the first connecting members, a sliding mounting member is detachably fixedly provided on the cross bar, a laser radar scanner is detachably fixedly provided on the sliding mounting member, a counterweight rod is detachably fixedly provided on the other first connecting member, and a counterweight block is detachably fixedly provided on the counterweight rod.

[0014] When using the above solution, the adjustable leveling tripod is used as the first module, the base plate, RTK module, support frame, top plate, rotating shaft and driving mechanism are used as the second module, the adjustable length crossbar is used as the third module, the sliding mounting part and the lidar scanner are used as the fourth module, and the counterweight rod and the counterweight block are used as the fifth module. The five modules can be disassembled and shipped during transportation and can also be quickly assembled at the measurement site, which provides extremely high efficiency for the measurement work in terms of transportation convenience and disassembly and assembly convenience.

[0015] When it is necessary to measure the flatness of the land, first place the adjustable leveling tripod of the first module on the land, then install the second module on the first module, then install the third module and the fifth module on the two first connecting pieces respectively, and then install the fourth module on the crossbar of adjustable length. Finally, the adjustable leveling tripod is leveled so that the shaft is in a vertical state and the crossbar is in a horizontal state. When the shaft rotates, the crossbar can make a circular motion in the horizontal direction, and the fourth module fixed on the crossbar can also make a circular motion in the horizontal direction. The laser radar scanner can quickly perform a circular scan at the same horizontal height. After scanning a circle, the position of the fourth module on the crossbar is replaced again, and multiple circular scans are performed from the inside to the outside, or from the outside to the inside. Finally, these circular terrain data are integrated to form circular terrain data with the shaft as the center point.

[0016] After measuring the circular terrain data of one location, the entire device is moved to another location to scan the circular terrain data, and then the circular terrain data of all locations are integrated to obtain the land flatness scanning result of the entire farmland.

[0017] Compared with the device that reciprocates in a straight line, this device has a larger single measurement area, is more convenient to move and level, and has higher measurement efficiency. Compared with the device installed on a mobile vehicle (such as a vehicle or drone), the laser radar scanner of this device keeps moving on the same horizontal plane during the measurement process, avoiding up and down vibrations, improving measurement accuracy, and making it possible to generate a topographic map by obtaining direct measurement data, avoiding the use of dynamic error correction, and reducing mapping errors.

[0018] A further technical solution is that the cross tube and the first connecting piece connected to the cross bar are both square tubes, the first connecting piece connected to the cross bar is perpendicular to the rotating shaft, a plurality of groups of through holes are opened on the square tube, the cross section of the first connecting piece is larger than the cross section of the cross bar, one end of the cross bar is slidably inserted into the first connecting piece, the outer wall of the cross bar and the inner wall of the first connecting piece are in contact with each other, and the cross bar and the first connecting piece are fixed by bolts passing through the through holes on the square tube and then screwed with nuts.

[0019] When using the above solution, the cross bar and the first connecting member connected to the cross bar are both arranged on the square tube, so that after the cross bar is connected to the first connecting member, its state is fixed, which is convenient for the subsequent sliding mounting part and the posture determination of the laser radar scanner.

[0020] A further technical solution is that the sliding mounting part includes a sliding sleeve arranged on the cross bar, and also includes an extension plate arranged on the side wall of the sliding sleeve. The cross-section of the sleeve hole inside the sliding sleeve is square and is exactly the same as the cross-sectional shape and size of the outer wall of the cross bar, so that the sliding sleeve can slide on the cross bar but cannot rotate or shake. The sliding sleeve is also provided with at least two groups of through holes that penetrate the through holes of the sliding sleeve and the through holes of the cross bar at the same time, and then the sliding sleeve is fixed by nuts. The laser radar scanner is detachably fixed on the extension plate.

[0021] When using the above solution, by setting the square shape inside the sleeve and coordinating the square tube shape of the cross bar and the first connecting member, when the rotating shaft is vertical, the sliding mounting member can quickly determine the posture, which is convenient for determining the installation posture of the laser radar scanner.

[0022] A further technical solution is that the cross bar includes a first cross bar and a second cross bar, the cross-sectional shape and size of the first cross bar and the second cross bar are exactly the same, and they show consistent thickness. A protrusion is provided at one end of the second cross bar for inserting into the first cross bar, and a threaded hole is provided on the protrusion. The second cross bar is slidably inserted into the first cross bar through the protrusion, and the outer wall of the protrusion fits with the inner wall of the first cross bar, and the outer wall of the protrusion fits with the inner wall of the first cross bar. The first cross bar corresponding to the threaded hole of the protrusion is also provided with a threaded hole that penetrates the first cross bar, and the first cross bar is also provided with a countersunk hole connected to the threaded hole of the first cross bar. The protrusion and the first cross bar are screwed and fixed by bolts passing through the countersunk hole and the threaded hole, and the head of the bolt is sunk in the countersunk hole.

[0023] When using the above solution, the crossbar is disassembled into two mutually connectable first and second crossbars, which facilitates the transportation of the crossbar. An overly long crossbar is not convenient for loading. The setting of the countersunk hole and the threaded hole is conducive to the quick connection of the first and second crossbars, while keeping the connection smooth and not protruding, and not affecting the sliding of the sliding mounting parts.

[0024] A further technical solution is that a second connecting piece is provided at the bottom of the second cross bar, and a third connecting piece is provided on the rotating shaft below the first connecting piece. The second connecting piece and the third connecting piece are also fixedly connected by a support rod, so that the cross bar, the rotating shaft and the support rod form a tripod structure. A through groove is also provided at the bottom of the sliding sleeve for the second connecting piece and the support rod to pass through, and the through groove is connected to the sleeve hole inside the sliding sleeve.

[0025] When the above solution is used, the structural strength of the crossbar can be strengthened by providing a support rod, thereby preventing the crossbar from bending, deforming and shaking up and down due to its length and weight.

[0026] A further technical solution is that the first connecting piece connected to the counterweight rod is a screw sleeve, the counterweight rod is a screw rod, the counterweight rod is screwed in the screw sleeve, the counterweight block is slidingly sleeved on the counterweight rod, and a limit block for limiting the counterweight block is also screwed on the counterweight rod.

[0027] When the above solution is used, the center of gravity of the entire device can be changed by adjusting the number of counterweights so that the center of gravity is close to the center of the rotating shaft, thereby increasing the stability of the adjustable tripod and the stability of the entire device.

[0028] A further technical solution is that the driving mechanism includes a driven gear fixedly mounted on the rotating shaft, the driven gear is coaxial with the rotating shaft, the driving mechanism also includes a servo motor fixed on the top plate, the output shaft of the servo motor is provided with a driving gear, and the driving gear is drivingly connected to the driven gear.

[0029] When the above solution is used, the servo motor rotates at a constant speed according to the instruction, drives the driven gear to rotate, and the driven gear drives the rotating shaft to rotate.

[0030] A method for measuring land flatness using the device described above, wherein the measuring steps are as follows:

[0031] S1, according to the scanning range of the laser radar scanner and the height of the crossbar, setting multiple scanning points of the laser radar scanner on the crossbar;

[0032] S2, when the shaft rotates, the laser radar scanner will scan a circular scanning area, where the scanning radius of the circular scanning area with the largest radius is set to the maximum scanning radius;

[0033] S3, plan a grid of measuring points on the field, and the distance between two adjacent measuring points is 1.00 to 1.45 times the maximum scanning radius;

[0034] S4, after moving the device to a measuring point, the RTK coordinate information of the measuring point is recorded through the RTK module;

[0035] S5, moving the sliding mounting member to different scanning points, and scanning the land data by a laser radar scanner while rotating the rotating shaft at different scanning points, obtaining circular terrain data of different radii, and generating a circular DEM model;

[0036] S6, fitting multiple circular DEM models at the same RTK coordinate point, so as to obtain a circular terrain DEM model at the RTK coordinate point;

[0037] S7, after moving the device to other multiple different measuring points, and repeating steps S4-S6, to obtain RTK coordinate information of multiple measuring points and a circular terrain DEM model corresponding to each RTK coordinate;

[0038] S8, extracting the longitude coordinate and the latitude coordinate from each RTK coordinate information through processing software, and distributing each RTK coordinate in the same coordinate system composed of the X-axis and the Y-axis according to the corresponding relationship between the longitude coordinate and the X-axis and the latitude coordinate and the Y-axis;

[0039] S9, bringing the circular terrain DEM model corresponding to each RTK coordinate into the coordinate system composed of the X and Y axes in step S8;

[0040] S10, fitting the overlapping areas of adjacent circular terrain DEM models, that is, merging the parts of adjacent circular terrain DEM models with the same model data, so that the overlapping parts of the adjacent circular terrain DEM models share the same data, thereby generating a new terrain DEM model.

[0041] S11, according to the method of arranging S10, starting from the RTK coordinates at the most corner, one by one is fitted in an 'S' shaped route until a complete terrain DEM model of the entire map is finally generated.

[0042] A further technical solution is that, in step S3, the distance between two adjacent measuring points is 1.42 to 1.45 times the maximum scanning radius.

[0043] The beneficial effects of the measuring device of the present invention are:

[0044] 1. Modular design: The device is cleverly designed into five modules. This design provides great convenience during transportation and assembly, greatly improving the efficiency of measurement work.

[0045] 2. Efficient measurement: This solution can quickly measure the flatness of a large area of ​​land. Through the circular scanning method, a larger area can be measured at a time, thereby improving measurement efficiency.

[0046] 3. High-precision measurement: Compared with devices installed on mobile carriers, the lidar scanner in this solution keeps moving on the same horizontal plane during the measurement process, effectively avoiding up and down vibrations and significantly improving measurement accuracy.

[0047] 4. Easy posture determination: The square tube design of the crossbar and the first connecting piece, as well as the square shape inside the sliding sleeve, enable the posture of the sliding mount and the lidar scanner to be quickly determined, further improving the accuracy and efficiency of the measurement.

[0048] 5. Easy to transport: The crossbar is disassembled into two crossbars, the first crossbar and the second crossbar, which can be connected to each other. This design makes it more convenient to transport the overly long crossbar.

[0049] 6. Stable structure: The setting of the support rod enhances the structural strength of the cross bar, effectively prevents the deflection and deformation of the cross bar and the up and down shaking, and ensures the stability of the measurement.

[0050] 7. Enhanced stability: By adjusting the number of counterweights, the center of gravity of the entire device can be changed to be close to the center of the shaft, thereby increasing the stability of the adjustable tripod and the stability of the entire device.

[0051] The beneficial effects of the measuring method of the present invention are:

[0052] 1. Efficient and comprehensive coverage: Through the grid-shaped measurement points and specific adjacent distances (1.42 to 1.45 times), the solution can efficiently cover the entire farmland area and ensure that there is overlap between adjacent scan areas. This overlap facilitates the subsequent data fitting processing.

[0053] 2. Optimize data processing: At the same RTK coordinate point, the data can be optimally fitted through the overlapping parts of multiple circular DEM models. This fitting method compares and unifies the relative elevation data of the overlapping parts, so that different circular DEM models can share a copy of the data, thereby constructing a complete and accurate circular terrain DEM model.

[0054] At different RTK coordinate points, the data can be optimally fitted through the overlapping parts of multiple circular terrain DEM models. This fitting method compares and unifies the relative elevation data of the overlapping parts, allowing different circular terrain DEM models to share a copy of the data, thereby constructing a complete and accurate full-map terrain DEM model.

[0055] 3. High-precision terrain recognition: Since the movement of the LiDAR scanner during the scanning process is almost close to translation, the relative elevation data obtained is highly consistent. This makes it easy to identify terrain areas with the same relative elevation through the fuzzy recognition algorithm, further improving the accuracy and efficiency of terrain recognition. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A schematic diagram of the device.

[0057] In the figure, 1. adjustable leveling tripod, 2. bottom plate, 3. support frame, 4. servo motor, 5. top plate, 6. driving gear, 7. lower limit member, 8. upper limit member, 9. driven gear, 10. rotating shaft, 11. first connecting member, 12. counterweight block, 13. limit block, 14. counterweight rod, 15. first cross bar, 16. second cross bar, 17. sliding mounting member, 18. lidar scanner, 19. second connecting member, 20. support rod, 21. third connecting member, 22. RTK module, 23. sliding sleeve, 24. extension plate. DETAILED DESCRIPTION

[0058] In order to better understand the technical content of the present invention, specific embodiments are provided below, and the present invention is further described in conjunction with the accompanying drawings.

[0059] See also Figure 1 , a device for measuring land flatness, comprises an adjustable leveling tripod 1.

[0060] It should be noted that the leveling tripod 1 includes a leveling tripod, a quadripod, or other types of tripods, which are commonly used tools in the prior art. The accompanying drawings only illustrate that the structure is a leveling tripod 1, and do not specifically refer to the specific structure of the leveling tripod 1 as shown in the accompanying drawings.

[0061] A bottom plate 2 is detachably fixed on the top of the leveling tripod 1 .

[0062] It should be noted that there are multiple ways to detachably mount the bottom plate 2 on the top of the leveling tripod 1, including screwing and snapping. The technician determines the mounting method of the bottom plate 2 according to the type of the leveling tripod 1 used.

[0063] A support frame 3 and an RTK module 22 are fixedly disposed on the upper end of the bottom plate 2 , a top plate 5 is fixedly disposed on the top of the support frame 3 , and a vertically disposed rotating shaft 10 is rotatably penetrated in the top plate 5 .

[0064] Specifically, a through hole is provided in the top plate 5, a bearing is provided in the through hole, the rotating shaft 10 is rotatably passed through the bearing, a lower limit piece 7 is provided at the bottom of the shaft seat, an upper limit piece 8 is fixedly sleeved on the rotating shaft 10 above the bearing, and the upper limit piece 8 and the lower limit piece 7 clamp the bearing in the middle.

[0065] The top plate 5 is also provided with a driving mechanism for driving the rotating shaft 10 to rotate.

[0066] Specifically, the driving mechanism includes a driven gear 9 fixedly mounted on a rotating shaft 10, and the driven gear 9 is coaxial with the rotating shaft 10. The driving mechanism also includes a servo motor 4 fixedly mounted on the bottom surface of the top plate 5. The output shaft of the servo motor 4 rotates upward and passes through the top plate 5 and is provided with a driving gear 6. The driving gear 6 is driven and connected to the driven gear 9.

[0067] Two first connecting members 11 are fixedly provided on the rotating shaft 10 at the upper end of the top plate 5 and are symmetrically arranged with the central axis of the rotating shaft 10 as the center. A cross bar with an adjustable length perpendicular to the rotating shaft 10 is detachably fixedly installed on one of the first connecting members 11, a sliding mounting member 17 is detachably fixedly installed on the cross bar, a laser radar scanner 18 is detachably fixedly installed on the sliding mounting member 17, and a counterweight rod 14 is detachably fixedly installed on the other first connecting member 11, and a counterweight block 12 is detachably fixedly installed on the counterweight rod 14.

[0068] Specifically, the cross tube and the first connecting member 11 connected to the cross bar are both square tubes. The first connecting member 11 connected to the cross bar is perpendicular to the rotating shaft 10. A plurality of through holes are provided on the square tube. The cross section of the first connecting member 11 is larger than the cross section of the cross bar. One end of the cross bar is slidably inserted into the first connecting member 11. The outer wall of the cross bar fits with the inner wall of the first connecting member 11. The cross bar and the first connecting member 11 are fixed by bolts passing through the through holes on the square tube and then screwed with nuts.

[0069] Specifically, the sliding mounting part 17 includes a sliding sleeve 23 which is arranged on the cross bar, and also includes an extension plate 24 which is arranged on the side wall of the sliding sleeve 23. The cross-section of the sleeve hole inside the sliding sleeve 23 is square and is exactly the same as the cross-sectional shape and size of the outer wall of the cross bar, so that the sliding sleeve 23 can slide on the cross bar but cannot rotate or shake. Two groups of through holes which penetrate each other are also provided on the sliding sleeve 23. The sliding sleeve 23 is fixed by bolts which pass through the through holes of the sliding sleeve 23 and the through holes of the cross bar at the same time and then are screwed with nuts. The laser radar scanner 18 is detachably fixed on the extension plate 24.

[0070] Specifically, the cross bar includes a first cross bar 15 and a second cross bar 16. The cross-sectional shape and size of the first cross bar 15 and the second cross bar 16 are exactly the same and show consistent thickness. A square columnar protrusion is provided at one end of the second cross bar 16 for inserting into the first cross bar 15. The protrusion is provided with a threaded hole that penetrates through. The second cross bar 16 is slidably inserted into the first cross bar 15 through the protrusion. The outer wall of the protrusion fits with the inner wall of the first cross bar 15. The outer wall of the protrusion fits with the inner wall of the first cross bar 15. The first cross bar 15 corresponding to the threaded hole of the protrusion is also provided with a threaded hole that penetrates through. The first cross bar 15 is also provided with a countersunk hole connected to the threaded hole of the first cross bar 15. The protrusion and the first cross bar 15 are screwed and fixed by bolts passing through the countersunk hole and the threaded hole, and the head of the bolt is sunk in the countersunk hole.

[0071] Specifically, a second connecting member 19 is further provided at the bottom of the second cross bar 16, and a third connecting member 21 is further provided on the rotating shaft 10 below the first connecting member 11. The second connecting member 19 and the third connecting member 21 are also fixedly connected by a support rod 20, so that the cross bar, the rotating shaft 10 and the support rod 20 form a tripod structure. A through groove is also provided at the bottom of the sliding sleeve 23 for the second connecting member 19 and the support rod 20 to pass through, and the through groove is connected to the sleeve hole inside the sliding sleeve 23.

[0072] Specifically, the first connecting member 11 connected to the counterweight rod 14 is a threaded sleeve, the counterweight rod 14 is a screw rod, the counterweight rod 14 is screwed in the threaded sleeve, the counterweight block 12 is slidably sleeved on the counterweight rod 14, and a limit block 13 for limiting the counterweight block 12 is also screwed on the counterweight rod 14.

[0073] The present invention also discloses a measurement method using the device for measuring land flatness as described above, wherein the calculation of the DEM model (digital elevation model) involved can be processed using software such as QGIS, White box GAT, Polycam, etc. The detailed processing method involved below (excluding the guidance method of the upper level improved in the steps) is a technology that can be implemented in the prior art and will not be described in detail here.

[0074] It should be noted that, when using this method, it is assumed that the rotating shaft 10 has been adjusted to be in a vertical state and the cross bar is in a horizontal state.

[0075] The measurement steps of this measurement method are as follows:

[0076] S1, according to the scanning range of the laser radar scanner 18 and the height of the crossbar, setting multiple scanning points of the laser radar scanner 18 on the crossbar;

[0077] S2, when the rotating shaft 10 rotates, the laser radar scanner 18 will scan a circular scanning area, wherein the scanning radius of the circular scanning area with the largest radius is set to the maximum scanning radius;

[0078] S3, plan a grid of measuring points on the field, and the distance between two adjacent measuring points is 1.00 to 1.45 times the maximum scanning radius;

[0079] Preferably, the distance between two adjacent measuring points is 1.42 to 1.45 times the maximum scanning radius.

[0080] When using the above scheme, the grid-shaped measuring points and the adjacent distance of 1.42 to 1.45 times can most efficiently cover the entire farmland and obtain overlapping parts in adjacent scanning areas to facilitate subsequent fitting processing.

[0081] S4, after moving the device to a measuring point, the RTK coordinate information of the measuring point is recorded by the RTK module 22;

[0082] S5, moving the sliding mounting member 17 to different scanning points, and scanning the land data by the laser radar scanner 18 while rotating the rotating shaft 10 at different scanning points, obtaining circular terrain data of different radii, and generating a circular DEM model;

[0083] S6, fitting multiple circular DEM models at the same RTK coordinate point, so as to obtain a circular terrain DEM model at the RTK coordinate point;

[0084] When using the above scheme, in multiple circular DEM models at the same RTK coordinate point, the innermost circle of the outer circular DEM model will partially overlap with the outermost circle of the inner circular DEM model. In the obtained circular DEM model, each surface point of the farmland will obtain a relative elevation (absolute elevation refers to the height difference between the surface point and the horizontal reference plane, and relative elevation refers to the relative height difference obtained by taking the highest and lowest points of the surface as reference points). Fitting is to compare the relative elevations of the data at these overlapping points, unify the two identical data, delete one and retain one, so that the outer circular DEM model and the inner circular DEM model share one data at the overlapping point, thereby forming a complete circular terrain DEM model.

[0085] Since the method applies the above-mentioned device, the laser radar scanner 18 is almost translated when scanning the same place, and the relative elevation data obtained are basically the same. The terrain area with the same relative elevation can be easily identified through the fuzzy recognition algorithm.

[0086] S7, after moving the device to other multiple different measuring points, and repeating steps S4-S6, to obtain RTK coordinate information of multiple measuring points and a circular terrain DEM model corresponding to each RTK coordinate;

[0087] S8, extracting the longitude coordinate and the latitude coordinate from each RTK coordinate information through processing software, and distributing each RTK coordinate in the same coordinate system composed of the X-axis and the Y-axis according to the corresponding relationship between the longitude coordinate and the X-axis and the latitude coordinate and the Y-axis;

[0088] S9, bringing the circular terrain DEM model corresponding to each RTK coordinate into the coordinate system composed of the X and Y axes in step S8;

[0089] S10, fitting the overlapping areas of adjacent circular terrain DEM models, that is, merging the parts of adjacent circular terrain DEM models with the same model data, so that the overlapping parts of the adjacent circular terrain DEM models share the same data, thereby generating a new terrain DEM model.

[0090] When the above solution is used, the fitting in step S10 and the fitting in step S6 refer to the same operation method, which will not be repeated here.

[0091] S11, according to the method of arranging S10, starting from the RTK coordinates at the most corner, one by one is fitted in an 'S' shaped route until a complete terrain DEM model of the entire map is finally generated.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for measuring land flatness, comprising a leveling tripod, a bottom plate is detachably fixed on the top of the leveling tripod, a support frame and an RTK module are fixed on the upper end of the bottom plate, and the device is characterized in that: A top plate is fixedly provided on the top of the support frame, a vertically arranged rotating shaft is rotatably penetrated in the top plate, a driving mechanism for driving the rotating shaft to rotate is also provided on the top plate, two first connecting members are fixedly provided on the rotating shaft at the upper end of the top plate and are symmetrically arranged with the central axis of the rotating shaft as the center, a cross bar with an adjustable length perpendicular to the rotating shaft is detachably fixedly installed on one of the first connecting members, a sliding mounting member is detachably fixedly installed on the cross bar, a laser radar scanner is detachably fixedly installed on the sliding mounting member, a counterweight rod is detachably fixedly installed on the other first connecting member, a counterweight block is detachably fixedly installed on the counterweight rod, the cross bar comprises a first cross bar and a second cross bar, the cross-sectional shape and size of the first cross bar and the second cross bar are exactly the same, showing a consistent thickness, and one end of the second cross bar is provided with a The protruding portion of the first cross bar is provided with a threaded hole that penetrates the protruding portion, and the second cross bar is slidably inserted in the first cross bar through the protruding portion, and the outer wall of the protruding portion fits with the inner wall of the first cross bar, and the outer wall of the protruding portion fits with the inner wall of the first cross bar. The first cross bar corresponding to the threaded hole of the protruding portion is also provided with a threaded hole that penetrates the protruding portion, and the first cross bar is also provided with a countersunk hole connected to the threaded hole of the first cross bar. The protruding portion and the first cross bar are screwed and fixed by bolts passing through the countersunk hole and the threaded hole, and the head of the bolt is sunk in the countersunk hole. A second connecting piece is also provided at the bottom of the second cross bar, and a third connecting piece is also provided on the rotating shaft below the first connecting piece. The second connecting piece and the third connecting piece are also fixedly connected by a support rod, so that the cross bar, the rotating shaft and the support rod form a tripod structure.

2. The device for measuring land flatness according to claim 1, characterized in that: The cross tube and the first connecting piece connected to the cross bar are both square tubes. The first connecting piece connected to the cross bar is perpendicular to the rotating shaft. A plurality of through holes are provided on the square tube. The cross section of the first connecting piece is larger than the cross section of the cross bar. One end of the cross bar is slidably inserted into the first connecting piece. The outer wall of the cross bar fits with the inner wall of the first connecting piece. The cross bar and the first connecting piece are fixed by bolts passing through the through holes on the square tube and then screwed with nuts.

3. A device for measuring land flatness according to claim 2, characterized in that: The sliding mounting part includes a sliding sleeve arranged on the cross bar, and also includes an extension plate arranged on the side wall of the sliding sleeve. The cross-section of the sleeve hole inside the sliding sleeve is square and is completely the same as the cross-sectional shape and size of the outer wall of the cross bar, so that the sliding sleeve can slide on the cross bar but cannot rotate or shake. The sliding sleeve is also provided with at least two groups of through holes that penetrate the through holes of the sliding sleeve and the through holes of the cross bar at the same time, and then the sliding sleeve is fixed by nuts. The laser radar scanner is detachably fixed on the extension plate.

4. The device for measuring land flatness according to claim 3, characterized in that: The bottom of the sliding sleeve is also provided with a through slot for the second connecting member and the support rod to pass through, and the through slot is connected to the sleeve hole inside the sliding sleeve.

5. A device for measuring land flatness according to any one of claims 1 to 4, characterized in that: The first connecting piece connected to the counterweight rod is a screw sleeve, the counterweight rod is a screw rod, the counterweight rod is screwed in the screw sleeve, the counterweight block is slidingly sleeved on the counterweight rod, and a limit block for limiting the counterweight block is screwed on the counterweight rod.

6. The device for measuring land flatness according to claim 5, characterized in that: The driving mechanism includes a driven gear fixedly sleeved on the rotating shaft, the driven gear and the rotating shaft are coaxial, and the driving mechanism also includes a servo motor fixed on the top plate, the output shaft of the servo motor is provided with a driving gear, and the driving gear is drivingly connected to the driven gear.

7. A method for measuring land flatness using the device for measuring land flatness according to any one of claims 1 to 6, characterized in that: The measurement steps are as follows: S1, according to the scanning range of the laser radar scanner and the height of the crossbar, setting multiple scanning points of the laser radar scanner on the crossbar; S2, when the shaft rotates, the laser radar scanner will scan a circular scanning area, where the scanning radius of the circular scanning area with the largest radius is set to the maximum scanning radius; S3, plan a grid of measuring points on the field, and the distance between two adjacent measuring points is 1.00~1.45 times the maximum scanning radius; S4, after moving the device to a measuring point, the RTK coordinate information of the measuring point is recorded through the RTK module; S5, moving the sliding mounting member to different scanning points, and scanning the land data by a laser radar scanner while rotating the rotating shaft at different scanning points, obtaining circular terrain data of different radii, and generating a circular DEM model; S6, fitting multiple circular DEM models at the same RTK coordinate point, so as to obtain a circular terrain DEM model at the RTK coordinate point; S7, after moving the device to other multiple different measuring points, and repeating steps S4-S6, to obtain RTK coordinate information of multiple measuring points and a circular terrain DEM model corresponding to each RTK coordinate; S8, extracting the longitude coordinate and the latitude coordinate from each RTK coordinate information through processing software, and distributing each RTK coordinate in the same coordinate system composed of the X-axis and the Y-axis according to the corresponding relationship between the longitude coordinate and the X-axis and the latitude coordinate and the Y-axis; S9, bringing the circular terrain DEM model corresponding to each RTK coordinate into the coordinate system composed of the X and Y axes in step S8; S10, fitting the overlapping areas of adjacent circular terrain DEM models, that is, merging the parts of adjacent circular terrain DEM models with the same model data, so that the overlapping parts of the adjacent circular terrain DEM models share the same data, thereby generating a new terrain DEM model; S11, according to the method of step S10, starting from the RTK coordinates at the most corner, one by one is fitted in an 'S' shaped route until a complete terrain DEM model of the entire map is finally generated.

8. A method for measuring land flatness according to claim 7, characterized in that: In step S3, the distance between two adjacent measuring points is 1.42 to 1.45 times of the maximum scanning radius.

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