A 3D leveling method and device for underground cement paver

Abstract

The present invention provides a 3D leveling method for an underground cement paver, which relates to the technical field of cement pavers and includes: obtaining the plane position of each column cylinder in real time through an indoor wireless positioning method; calculating the theoretical telescopic height corresponding to each column cylinder in real time based on the three-dimensional data of the pavement of the paved section, the designed paving height of the formed pavement, and the plane position of each column cylinder; determining the actual telescopic height of each column cylinder in real time using an elevation measuring instrument; comparing the actual telescopic height with the theoretical telescopic height and outputting a control signal to independently control each column cylinder, so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel plate to maintain a preset height and posture during operation. The present application can be applied to underground roadway pavement construction, using an indoor wireless positioning method to replace the existing GPS positioning method, thereby realizing application in an underground operation construction environment.

Description

Technical Field

[0001] The present application relates to the technical field of cement pavers, and in particular to a 3D leveling method and device for an underground cement paver. Background Art

[0002] Roadways are crucial locations in underground coal mining, but the pavement conditions within these tunnels are often poor, adversely impacting the passage of various types of transport vehicles. Therefore, the quality of underground roadway conditions directly impacts coal mining efficiency, and improving the construction quality of roadway pavements is crucial for improving coal mining efficiency and alleviating the imbalance between supply and demand. Underground roadway pavement construction is typically performed manually, a method with limited automation and low efficiency, often failing to guarantee pavement quality. Therefore, slipform cement pavers specifically designed for underground roadway cement pavement construction are needed. Using a cement paver for roadway pavement paving can greatly improve construction efficiency, shorten coal mine construction and mining cycles, and produce a high-quality paved surface. When a slipform cement paver is performing pavement paving, the performance of its leveling system plays a decisive role in determining the pavement quality. The leveling system is a crucial component of the paver's operating system.

[0003] Traditional slipform cement paver leveling systems typically utilize contact-type wire leveling. This mechanical leveling system has a low level of automation and is susceptible to interference from adverse factors when used in roadways, such as deep potholes, sagging baselines, and rapid changes in paver speed, resulting in suboptimal leveling results. Furthermore, the shape and structure of the paved surface differ significantly between slipform paving in underground roadways and conventional surface roads. Wire leveling is subject to limitations in roadway space, various slopes, and curves, making initial manual operations complex, time-consuming, and labor-intensive. In addition to wire-type contact leveling, non-contact automatic leveling systems that directly detect road surface irregularities, such as laser and ultrasonic leveling systems, are currently in widespread use. However, due to the poor condition of the original roadway base surface, including potholes and muddy terrain, significant variations in slope, and high road surface irregularities, the performance of non-contact leveling systems is significantly compromised underground.

[0004] 3D paving is a new paving technology currently widely used in conventional above-ground highway paving construction. It boasts high paving efficiency, simple construction, and high-quality pavement formation. Its principle relies on 3D positioning to level the paver, thereby achieving high-precision control of pavement quality. However, in current 3D paving of above-ground highways, the paver's target plane is located using a GPS positioning system based on satellite signals. Due to signal shielding, this technology is completely infeasible underground. Therefore, it is necessary to redesign the operating system based on the principle of 3D leveling to enable cement pavers to stably perform 3D slipform paving underground. Summary of the Invention

[0005] The technical problem to be solved by this application is to propose a 3D leveling method and device for an underground cement paver in response to the above-mentioned deficiencies in the prior art.

[0006] A 3D leveling method for an underground cement paver, the underground cement paver comprising a crawler chassis, a frame, a trowel plate, and column cylinders, wherein the frame is connected to the crawler chassis via four column cylinders, the crawler mechanisms on both sides of the crawler chassis each corresponding to two column cylinders, and the column cylinders are telescopically adjustable to adjust the height of the frame; the trowel plate is fixedly connected to the frame; the 3D leveling method comprises:

[0007] The plane position of each column cylinder is obtained in real time through indoor wireless positioning methods;

[0008] Based on the 3D data of the paving section, the designed paving height of the formed road surface, and the plane position of each column cylinder, the corresponding theoretical telescopic height of each column cylinder is calculated in real time;

[0009] Use height measuring instruments to determine the actual telescopic height of each column cylinder in real time;

[0010] The actual telescopic height is compared with the theoretical telescopic height and a control signal is output to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel to maintain a preset height and posture during operation.

[0011] In an improved technical solution, the wireless positioning method is implemented using a UWB positioning system;

[0012] The UWB positioning system performs planar positioning of each column cylinder through signal interaction between multiple UWB positioning base stations and positioning tags on each column cylinder.

[0013] In an improved technical solution, the UWB positioning system specifically adopts a multi-signal TDOA ranging method.

[0014] In an improved technical solution, the multi-signal TDOA ranging method specifically adopts the FANG positioning algorithm.

[0015] In an improved technical solution, the FANG positioning algorithm is based on a four-base station positioning system.

[0016] In an improved technical solution, the elevation measuring instrument is implemented using spatial domain laser emission technology; wherein, the spatial domain laser transmitter total station of the elevation measuring instrument is set up at a preset point on the tunnel reference surface, and the laser receiver of the elevation measuring instrument is set on the column cylinder. By receiving signals multiple times, the elevation difference of the laser receiver relative to the laser axis surface can be calculated, thereby obtaining the absolute measurement elevation of the position of the laser receiver.

[0017] In an improved technical solution, the actual telescopic height is compared with the theoretical telescopic height and a control signal is output to independently control each column cylinder. Specifically,

[0018] The actual telescopic height is compared with the theoretical telescopic height to generate an elevation deviation electrical signal and output it to the hydraulic system of the paver to drive the hydraulic control valve to control the flow and direction of the oil circuit to achieve up and down adjustment of the column cylinder.

[0019] In an improved technical solution, the four column cylinders include a pair of column cylinders arranged at the front side of the frame and a pair of column cylinders arranged at the rear side of the frame; wherein, in each pair of column cylinders, one is arranged at the left side of the frame and the other is arranged at the right side of the frame, and the front and rear positions of the two column cylinders are consistent;

[0020] The four column cylinders are supplied with oil through a hydraulic oil source, which is connected to the oil inlets of two diverter valves; each diverter valve is provided with two oil outlets, corresponding to a pair of column cylinders; the oil outlets of the diverter valves correspond one-to-one to the column cylinders, and a control oil circuit is provided between the two; a hydraulic lock and an electro-hydraulic servo valve for controlling the extension and retraction of the column cylinders are provided on the control oil circuit.

[0021] In an improved technical solution, the piston rod of the column cylinder is a fixed end, and the frame is fixedly connected to the cylinder barrel of the column cylinder. The height of the cylinder barrel, and thus the position of the floating frame, is adjusted by hydraulic drive. When the cylinder barrel of the column cylinder rises, oil enters the rodless chamber of the hydraulic cylinder and oil returns to the rod chamber. The system needs to overcome the force generated by the fixed load force and inertial mass to push the cylinder barrel up. When the column cylinder descends, oil enters the rod chamber of the hydraulic cylinder and oil returns to the rodless chamber. At this time, the load force and inertial mass act as the driving force, and together with the oil pressure, push the cylinder barrel down.

[0022] During the cylinder rising process, the servo valve linearized flow equation is:

[0023] qL =k q1 x v -k c1 p L

[0024] Among them, k q1 —Flow gain of electro-hydraulic servo valve, that is

[0025] k c1 —Flow pressure coefficient of electro-hydraulic servo valve, that is

[0026] λ1 is the load flow ratio coefficient, C d is the flow coefficient, W is the valve opening area gradient, p S is the oil inlet pressure of the electro-hydraulic servo valve, γ is the ratio of the flow rate out of the hydraulic cylinder to the flow rate into the hydraulic cylinder, p L is the equivalent load pressure, ρ is the hydraulic oil density, x v is the valve core displacement, q L is the load flow;

[0027] During the cylinder rising process, the flow continuity equation of the asymmetric hydraulic cylinder is:

[0028]

[0029] in, is the proportional coefficient, Ae is the average pressure bearing area of ​​the asymmetric cylinder, x P is the displacement of the column cylinder, C tp is the total leakage coefficient of the asymmetric cylinder, V0 is the total initial volume of the hydraulic cylinder when the hydraulic spring stiffness is the smallest, p L is the equivalent load pressure, β e is the effective bulk modulus, t is the time;

[0030] During the cylinder rising process, the equilibrium equation between the asymmetric cylinder and the load force is:

[0031]

[0032] Among them, A 01 is the equivalent bearing area, m is the equivalent inertial mass, F is the equivalent fixed load force, B P is the viscous damping coefficient, K is the load spring stiffness;

[0033] The dynamic response characteristics of hydraulic power components are related to the load characteristics. During the rising process of the cylinder, the load force includes any external load force, inertia force, elastic force and damping force;

[0034] During the cylinder rising process, the transfer function of the system model is:

[0035] Displacement X p The transfer function of the valve core displacement Xv is:

[0036]

[0037] Displacement X p The transfer function of the load force F is:

[0038]

[0039] Among them, ω h1 is the hydraulic natural frequency, ζ h1 is the hydraulic damping ratio, K ce1 is the total flow-pressure coefficient of the system, s is the Laplace operator;

[0040] During the cylinder descending process, the linearized flow equation of the servo valve is:

[0041] q L =k q2 x v -k c2 p L

[0042] Among them, k q2 —Flow gain of electro-hydraulic servo valve, that is

[0043] k c2 —Flow pressure coefficient of electro-hydraulic servo valve, that is

[0044] Among them, λ2 is the load flow proportional coefficient;

[0045] During the cylinder barrel descending process, the flow continuity equation of the asymmetric hydraulic cylinder is:

[0046]

[0047] in, is the proportionality coefficient;

[0048] During the cylinder barrel descending process, the equilibrium equation between the asymmetric cylinder and the load force is:

[0049]

[0050] During the cylinder's descent, the transfer function of displacement Xp to valve core displacement Xv is:

[0051]

[0052] During the cylinder's descent, the displacement X p The transfer function of the load force F is:

[0053]

[0054] Among them, ω h2 is the hydraulic natural frequency, ζ h2 is the hydraulic damping ratio, K ce2 is the total flow-pressure coefficient of the system.

[0055] On the other hand, the present application also provides a 3D leveling device for an underground cement paver, wherein the underground cement paver comprises a crawler chassis, a frame, a trowel plate, and a column cylinder, wherein the frame is connected to the crawler chassis via four column cylinders, and the crawler mechanisms on both sides of the crawler chassis each correspond to two column cylinders, and the column cylinders can be telescopically adjusted to adjust the height of the frame; the trowel plate is fixedly connected to the frame; and the 3D leveling device comprises:

[0056] Position acquisition module, used to obtain the plane position of each column cylinder in real time through indoor wireless positioning method;

[0057] A calculation module is used to calculate the theoretical telescopic height corresponding to each column cylinder in real time based on the three-dimensional data of the paving section pavement, the designed paving height of the formed pavement, and the plane position of each column cylinder;

[0058] A determination module is used to determine the actual telescopic height of each column cylinder in real time using a height measuring instrument;

[0059] The control module is used to compare the actual telescopic height with the theoretical telescopic height and output a control signal to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel plate to maintain a preset height and posture during operation.

[0060] The present application provides a method for hydraulic leveling of four columns of a paver. Each column cylinder has a unique theoretical design height corresponding to any plane position during the paving process. By measuring the plane position of the space where the column cylinder is located in real time, the theoretical height of the column at that plane position can be obtained in the model of the main controller. At the same time, the real-time height of the column is measured by an elevation measuring instrument, and by comparison, it can be determined whether there is a deviation in the height of the column. If there is a deviation, the frame can be adjusted by the column cylinder. The present application can be applied to the construction of underground roadways. An indoor wireless positioning method is used to replace the existing GPS positioning method, realizing its application in underground construction environments. The use of a 3D leveling system for road paving can greatly improve the road quality of coal mine roadways, thereby directly improving the efficiency of underground transportation. For more specific descriptions, please refer to the specific implementation method section. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1It is a structural diagram of the cement paver in the embodiment of the present application.

[0062] Figure 2 This is a flow chart of the 3D leveling method of the underground cement paver in the embodiment of the present application.

[0063] Figure 3 It is a schematic diagram of the posture and height control of the paving machine trowel plate in the embodiment of the present application.

[0064] Figure 4 This is one of the schematic diagrams of the relative positions of the trowel plate, the frame, and the column cylinder in the embodiment of the present application.

[0065] Figure 5 This is the second schematic diagram of the relative positions of the trowel plate, the frame, and the column cylinder in the embodiment of the present application.

[0066] Figure 6 The workflow diagram of the 3D leveling system is established according to the principle of the 3D leveling system in the embodiment of the present application.

[0067] Figure 7 It is a structural block diagram of the receiver in an embodiment of the present application.

[0068] Figure 8 This is a construction diagram of a paved road surface with a horizontal slope in an embodiment of the present application.

[0069] Figure 9 This is a construction diagram of a paved road surface with a longitudinal slope in an embodiment of the present application.

[0070] Figure 10 It is a schematic diagram of the underground UWB planar positioning system in an embodiment of the present application.

[0071] Figure 11 This is a schematic diagram of the base station lane distribution of the positioning system using four base stations for ranging in an embodiment of the present application.

[0072] Figure 12 This is a schematic diagram of the distribution of base station piles in the embodiment of this application.

[0073] Figure 13 Schematic diagram of the laser height measurement system in an embodiment of the present application.

[0074] Figure 14 Schematic diagram of the electro-hydraulic servo leveling system in an embodiment of the present application.

[0075] Figure 15 It is a structural diagram of the TDOA positioning system organization in the embodiment of the present application.

[0076] Figure 16 It is a line graph of the root mean square error of the positioning results of each algorithm in the embodiment of the present application.

[0077] Figure 17 It is a line graph of the positioning error of the CHAN algorithm with different numbers of base stations in the embodiment of the present application.

[0078] Figure 18 It is a schematic diagram of the column leveling hydraulic system in the embodiment of the present application.

[0079] Figure 19 It is a schematic diagram of the valve-controlled asymmetric hydraulic cylinder in an embodiment of the present application.

[0080] Figure 20 It is a structural block diagram of the 3D leveling device of the underground cement paver in the embodiment of the present application. DETAILED DESCRIPTION

[0081] The following are specific embodiments of the present application and in conjunction with the accompanying drawings, the technical scheme of the present application is further described, but the application is not limited to these embodiments. In the following description, specific details such as specific configurations and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures has been omitted.

[0082] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0083] refer to Figure 1 and Figure 2 This application provides a 3D leveling method for an underground cement paver, comprising steps S101 to S104. This 3D leveling method is applicable to underground cement pavers and can replace existing GPS positioning methods with indoor wireless positioning methods in underground coal mining tunnels, enabling its application in underground construction environments. The following describes this 3D leveling method in detail with reference to the accompanying figures.

[0084] refer to Figure 1In the embodiment of the present application, an underground cement paver comprises a crawler chassis 3, a frame 4, a trowel plate 1, and column cylinders 2. The frame 4 is connected to the crawler chassis 3 via four column cylinders 2. The crawler mechanisms on both sides of the crawler chassis 3 each correspond to two column cylinders 2, and the column cylinders 2 can telescopically adjust the height of the frame 4. The trowel plate 1 is fixedly connected to the frame 4. During the paving operation, the final shaping of the road surface height is completed by the paver's trowel plate. This paver does not use a floating trowel plate, but instead fixes the trowel plate 1 to the frame 4. The frame 4 as a whole floats up and down, allowing the paver to smooth the concrete by its own weight. The cement paver uses a dual-track walking chassis. The four column cylinders of the frame are fixed to the crawler mechanisms on both sides respectively. The frame column cylinders are independent of each other, and the connection structure is a piston hydraulic cylinder. The four column cylinders can only move up and down. When a paver is paving, changes in the road surface cause the crawler chassis to move, which in turn causes the frame structure to move up and down. This results in uneven road surfaces after the trowel plate, which is fixed to the frame, forms. The 3D leveling system needs to promptly detect changes in the trowel plate height caused by road surface changes during paving operations and use calculations and analysis to quickly and stably adjust the height of each column cylinder of the frame.

[0085] refer to Figure 2 The 3D leveling method includes steps S101 to S104, specifically:

[0086] In step S101, the planar position of each column cylinder is obtained in real time through an indoor wireless positioning method.

[0087] In step S102, the theoretical telescopic height corresponding to each column cylinder is calculated in real time based on the three-dimensional data of the paving section pavement, the designed paving height of the formed pavement, and the plane position of each column cylinder.

[0088] In step S103, the actual telescopic height of each column cylinder is determined in real time using a height measuring instrument.

[0089] In step S104, the actual telescopic height is compared with the theoretical telescopic height and a control signal is output to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, so that the trowel plate maintains the preset height and posture during operation.

[0090] Specifically, for a road surface to be paved, theoretically, the height of each point on the road surface is determined after paving is completed. Topcon 3D-Office, a professional modeling software from Topcon, can be used to process the road construction data, and the original surface data of the paving section and the designed paving height of the formed road surface and other information can be imported into the main controller of the paver through three-dimensional digital modeling. The pavement is formed by the trowel plate of the paver. The theoretical design value of the formed road surface can be used to determine the real-time theoretical position of the trowel plate during the paving process. The ideal paved road surface can be obtained by ensuring that its posture and height are always at the theoretical value. The schematic diagram of the posture and height control of the paver trowel plate is shown in the figure below. Figure 3 shown.

[0091] The trowel plate compacts and smoothes the concrete layer using the paver's own weight. If the trowel plate's position is consistently maintained at the designed paving height shown in the diagram, a highly flat cement pavement can be achieved. Therefore, the essence of a 3D leveling system is to control the trowel plate's position through three-dimensional positioning. However, since the trowel plate is located at the bottom of the paver, surrounded by numerous obstructions and subject to strong signal interference, direct positioning of the trowel plate is difficult. Given the relatively fixed positions of the trowel plate and the paver frame, this method uses the four columns of the paver to locate the trowel plate, indirectly obtaining its spatial position information through coordinate transformation. Figure 4 and Figure 5 This is a schematic diagram of the relative positions of the trowel plate and the frame column. The column here is the column cylinder.

[0092] Furthermore, the design height of the four column cylinders can be calculated from the design height of the trowel plate through the relative position relationship between the four column cylinders and the trowel plate. During paving operations, the height of the column cylinders is sufficient and the surrounding area is open for easy positioning. Keeping the frame columns in the corresponding spatial positions can ensure that the trowel plate is in the designed theoretical position.

[0093] Further references Figure 6 According to the three-dimensional data model of the pavement of the paving section, each column has a unique theoretical design height corresponding to any plane position during the paving process. If the plane position of the column can be measured in real time, the theoretical height of the column at that plane position can be obtained in the model of the main controller. At the same time, the real-time height of the column is measured using an elevation measuring instrument. By comparison, it can be determined whether there is a deviation in the height of the column. If there is a deviation, the frame can be adjusted through the column cylinder. According to the principle of the 3D leveling system, its work flow diagram is established as follows Figure 6 shown.

[0094] In summary, the 3D leveling system mainly includes the following parts: Plane positioning process: The plane position of each of the four columns of the frame is located. The positioning server calculates its plane position through the distance information between the base station and the tag, and then transmits it to the main controller of the paver. Elevation measurement process: When the paver is operating, the absolute height of the four columns is monitored in real time by an elevation measuring instrument, and the elevation information is transmitted to the main controller of the paver. Control process: The main controller matches the column position of the plane positioning system with the position in the three-dimensional data model, and obtains the theoretical design height of the column at the plane position. It then compares the measured real-time height to generate a position deviation, outputs a position deviation adjustment signal, and then controls the column cylinder. Leveling process: Respond quickly to the position deviation adjustment signal output by the main controller, and adjust the column cylinder to ensure that its height is always at the corresponding theoretical design height in the three-dimensional digital model of the main controller.

[0095] In an embodiment of the present application, the actual telescopic height is compared with the theoretical telescopic height and a control signal is output to independently control each column cylinder. Specifically, the actual telescopic height is compared with the theoretical telescopic height to generate an elevation deviation electrical signal and output it to the hydraulic system of the paver to drive the hydraulic control valve to control the flow and direction of the oil circuit to achieve up and down adjustment of the column cylinder.

[0096] In an embodiment of the present application, the frame is connected to the crawler chassis via four column cylinders. Two column cylinders correspond to each crawler mechanism on either side of the crawler chassis, and the column cylinders are capable of telescoping to adjust the height of the frame. The trowel plate is fixedly connected to the frame. Specifically, the barrel of the column cylinder is fixed to the frame, while one end of the piston rod is vertically fixed to the crawler chassis of the paver. As the column cylinders are extended or retracted, the height of the barrel of the column cylinder relative to the frame changes. The telescopic height, including the actual telescopic height and the theoretical telescopic height, refers to the corresponding column cylinder position, the height of the positioning label on the barrel or frame.

[0097] It's important to note that, as the 3D leveling workflow diagram shows, the planar positioning of the column cylinders is a prerequisite for achieving 3D leveling underground. Accurate planar positioning is essential to determining the precise theoretical height of the column cylinders, enabling subsequent hydraulic leveling control of the columns. The underground working environment differs from that above ground. While 3D leveling systems for above-ground cement spreaders typically utilize GPS satellite positioning to determine the planar position of the columns, satellite signals are unavailable underground, necessitating the use of precise indoor positioning technology.

[0098] In some embodiments of the present application, the wireless positioning method is implemented using a UWB positioning system; the UWB positioning system performs planar positioning of each column cylinder through signal interaction between multiple UWB positioning base stations and positioning tags on each column cylinder.

[0099] Common positioning technologies used in modern engineering applications include Wi-Fi, ZigBee, RFID, UWB, and Bluetooth. These are some of the most commonly used indoor positioning technologies. Below, we compare these technologies based on accuracy, interference immunity, penetration, system complexity, and cost.

[0100] Table 1 - Comparison of several positioning technologies:

[0101]

[0102]

[0103] In the 3D leveling system, the main function of plane positioning is to locate the position of the column as accurately as possible, so positioning accuracy is the most important performance indicator that determines the downhole plane positioning technology. The second is the signal penetration and anti-interference performance of this technology in the complex environment of the downhole, the purpose is to ensure that the system can work stably. Finally, it must also meet the conditions that the system layout is not too complicated and the production and manufacturing costs are not too high. In summary, the selection of downhole plane positioning technology should improve the positioning accuracy as much as possible on the basis of meeting the secondary conditions, so this application uses UWB positioning technology to realize the positioning of the positioning tag on the column cylinder. Although UWB is more expensive than several other technologies, it has good working stability and extremely high positioning accuracy, which is more in line with the requirements of downhole related performance.

[0104] When used underground in coal mines, UWB pulse signals use amplitude modulation to transmit information. Although the bit error rate performance of this method is not optimal in indoor environments, pulse amplitude modulation only requires a pulse generator and a matching filter in the hardware system, and can flexibly use multi-base modulation. Using this signal modulation method can greatly reduce the complexity of underground positioning hardware system design. Generally speaking, the advantages outweigh the disadvantages.

[0105] Due to the special environment underground, the UWB positioning system needs to have the characteristics of simple structure, easy implementation, and small size. Therefore, its signal receiving system tends to adopt a non-coherent receiving method based on energy detection. The composition structure of this receiving system generally includes several main parts: filter amplifier unit, square law device, integrator and baseband processing module. First, the signal received by the antenna enters the square law device after filtering. The detected signal is integrated under the synchronous control of the baseband processing module to obtain its energy. The collected energy is judged in the baseband processing unit, and then the data is demodulated. The receiver structure block diagram is shown as follows: Figure 7 shown.

[0106] The following is a detailed analysis of the underground road paving situation. Due to the existence of the roadway road transverse slope and natural longitudinal slope, the theoretical design height of the paver frame column is different at each position during the process of travel, and the theoretical design heights of the four columns are also quite different from each other. Therefore, the spatial positioning of the four columns should be independent of each other and carried out in real time. Figure 8 As shown. In some sections of the roadway, the original foundation may have a certain longitudinal slope, that is, the ups and downslope sections in the roadway. This longitudinal slope is generally large in range and long in distance. It is generally impossible to cover and level the entire surface during paving operations. The longitudinal slope needs to be retained. The cement paver is in an ups and downslope state as a whole. At this time, the paver leveling is relative to the longitudinal slope. The longitudinal slope diagram of the road surface is shown as follows: Figure 9 shown.

[0107] Furthermore, the UWB ultra-wideband positioning system mainly uses the signal interaction between multiple base stations and tags on the pillars to perform distance measurement and plane positioning between the two. During underground paving operations, each base station is located at a fixed position on both sides of the tunnel to locate the real-time mobile tags. The principle diagram is shown below. Figure 10 shown.

[0108] Further, Figure 11 This is a schematic diagram of the base station distribution in a positioning system that uses four base stations for ranging. In a straight lane, a four-base station positioning solution generally requires six positioning base stations, which are distributed at the six base station piles in the figure below. The interval L between the base station piles on the same side is 100 meters, and every 100 meters is a paving section. In addition, there are some curves in the underground lanes, and the paving operation on the curves is different from that on the straights. Using four-base station positioning, the total number of base stations required for a single section is seven. The base station pile distribution diagram is as follows: Figure 12 shown.

[0109] refer to Figure 13 In the embodiment of the present application, the height measuring instrument is implemented by spatial domain laser emission technology; wherein, the spatial domain laser transmitter total station of the height measuring instrument is set up at a preset point of the roadway reference surface, and the laser receiver of the height measuring instrument is set on the column cylinder. By receiving signals multiple times, the height difference of the laser receiver relative to the laser axis surface can be calculated, thereby obtaining the absolute measurement height of the position where the laser receiver is located. The working principle is as follows Figure 13 In addition, it should be noted that because the plane positioning point and the elevation measurement point should be the same point, the position and height of the laser receiver on the column need to be consistent with the signal receiving tag of the UWB plane positioning system.

[0110] When the actual elevation of the column measured by the laser measurement system is inconsistent with the theoretical elevation obtained by UWB plane positioning, the height of the column needs to be adjusted according to the elevation deviation signal generated by the main controller. This application uses a typical electro-hydraulic servo control system to level the four columns. The column cylinder in the electro-hydraulic servo system is the leveling actuator. The hydraulic control system receives the elevation deviation electrical signal from the main controller of the paver and uses it to drive the hydraulic control valve to control the flow and direction of the oil circuit, thereby realizing the up and down movement of the column cylinder. Please refer to the schematic diagram of the electro-hydraulic servo leveling system. Figure 14 .

[0111] The UWB positioning system is described in detail below with reference to the accompanying drawings.

[0112] UWB surface positioning methods include time of arrival (TOA), time difference of arrival (TDOA), and angle of arrival (AOA). Due to environmental factors, even a very small error in the angle of incidence estimation in the AOA positioning method, which measures the signal's angle of incidence, can result in significant errors in position estimation during construction. This results in low system reliability when used in underground construction. The TOA positioning method uses the direct arrival time of the UWB signal to perform ranging calculations, leveraging the advantages of wide signal bandwidth and high temporal resolution. It is widely used in indoor environments. However, TOA positioning relies on direct time of arrival ranging. Due to the technical difficulties in achieving high-precision synchronization between the base station and mobile tag clocks, its one-way ranging mode has low positioning accuracy and is unsuitable for paving machine leveling surface positioning systems. While two-way ranging avoids the clock synchronization issue in principle, the long delay in the ranging process caused by the round-trip signal transmission between the transmitter and receiver makes it less real-time than the mobile tag positioning requirements for paving machines. TDOA positioning can be seen as an improved version of TOA positioning. It uses the arrival time difference to construct a hyperbola intersection positioning that is different from conventional circular positioning. The tag node sends signals to different base station nodes at the same time, and the system delay of the ranging process is very small. In addition, based on the time difference method, the clock synchronization problem between base stations and tags can be converted into synchronization between each base station in the UWB system, and the ranging accuracy will be greatly improved. In summary, the performance of the TDOA positioning method in all aspects meets the requirements of precise positioning underground. Therefore, in the embodiment of the present application, the UWB positioning system specifically adopts the multi-signal TDOA ranging method.

[0113] The organizational structure of the TDOA positioning system is as follows Figure 15As shown in the figure, the underground positioning system based on the TDOA model mainly consists of three modules, namely the positioning base station, the positioning tag and the positioning server, which together constitute the UWB plane positioning system in 3D leveling. (1) The positioning base stations are located on both sides of the roadway, and their positions are equidistant with each section of the paved road. The positions of the base station piles at each location are pre-designed and stored in the positioning server. The positioning base station interacts with each positioning tag through a UWB signal with a specific ID number to calculate the distance between the base station and the tag. The interaction process begins with the tag sending a ranging request to the base station. After receiving the request signal, the base station sends a ranging signal, and then the tag sends a signal back to the base station to complete an interactive ranging. (2) The positioning tag and the positioning server are both on the cement paver. The positioning server is the core of the positioning system. It is responsible for solving the tag position in real time. The positioning server will solve the plane position coordinates of the tag based on the ranging information transmitted by different positioning base stations. The positioning server communicates with the UWB transmitting base station through an Ethernet switch. The server receives the UWB signal timestamps recorded by each base station and further processes these time data to establish a set of hyperbolic equations based on the arrival time difference of TDOA ranging. Finally, an advanced algorithm is used to find the optimal solution to the set of equations to obtain the coordinates of the positioning tag. (3) The real-time position coordinates of the mobile tag calculated by the positioning server will be transmitted to the main controller of the paver and compared with the pre-imported 3D data design model of the road pavement to obtain the theoretical design height of the column tag. At the same time, the system will display the coordinates and height parameters in real time on the user interface of the paver central console.

[0114] Furthermore, choosing a suitable position solution algorithm can improve the accuracy of system positioning. The following is a specific analysis of the FANG positioning algorithm, CHAN positioning algorithm, and TAYLOR positioning algorithm of the TDOA positioning model. The positioning performance of each algorithm is simulated in a simulated environment to verify the positioning accuracy of each algorithm.

[0115] The embodiment of the present application conducts simulation experiments on the three positioning algorithms FANG, CHAN, and TAYLOR in static and dynamic environments based on a simulation environment. In the static environment, multiple position calculations of each positioning algorithm are performed on fixed-position tags, and the advantages and disadvantages of each algorithm can be intuitively seen; the dynamic environment simulates the movement of the mobile tags on the leveling columns when the paver is working, and the simulation results can show the positioning performance of each algorithm.

[0116] The specific distribution of static positioning calculation results and simulation time of the three algorithms are shown in Table 2 below:

[0117]

[0118] The static solution results of each algorithm are all within a local range of the true position. The FANG algorithm has a larger positioning range, with maximum positioning errors reaching 0.078m and 0.088m in the x and y directions, respectively. This indicates that the direct linearized equation solution method has poor ranging and positioning performance. With the CHAN algorithm, except for a few positioning points falling within the range of -0.07-0.04m in the x direction, the vast majority of positioning results are within 0.04m of the true value in the x and y directions. Compared to the CHAN algorithm, the TAYLOR algorithm has a significantly lower probability of large positioning errors, with the vast majority of positioning results falling within 0.035m in the x and y directions, demonstrating higher solution accuracy. After eliminating a few large error points, the dynamic positioning accuracy of all three algorithms can be controlled within 0.04m. The FANG algorithm, due to limitations in its nature, struggles to maintain positioning accuracy within a small range, resulting in significant fluctuations in real-time positioning results. The CHAN and TAYLOR algorithms stably control positioning within 0.03m, and with the exception of a few individual points, the positioning accuracy of most other points is concentrated within a small range of 0.02m, resulting in very high positioning accuracy.

[0119] The above specific solution process of the algorithm is carried out under the premise of uniform random measurement error. When the measurement error is different, it is unknown whether the positioning performance of each algorithm can still maintain stability. Below we use the root mean square error indicator to quantitatively analyze the positioning performance of each algorithm under different ranging errors. Based on the software, repeated experiments are carried out in a static environment. 1000 position solution experiments are carried out in the range of TDOA ranging error of 0.01m-0.09m. The root mean square error line graph of each 1000 position solution results is as follows Figure 16 As shown. Figure 16 It can be seen that the positioning performance of each algorithm is different under different ranging errors, and the gap is large. When the ranging error increases, the positioning performance of various algorithms also deteriorates, and the positioning accuracy of the algorithm continues to decrease with the increase of the ranging error. Among them, the positioning accuracy of the FANG algorithm decreases rapidly as the error increases. Under the same error condition, its positioning performance is far inferior to the CHAN algorithm and the TAYLOR algorithm. In addition, it can be seen from the figure that there is also a difference in the positioning accuracy of the CHAN and TAYLOR algorithms under the same ranging error, and the difference becomes greater as the error increases. When the accuracy of the downhole TDOA ranging is below 0.03m, the CHAN algorithm and the TAYLOR algorithm can both achieve high-precision planar positioning downhole, and the CHAN algorithm is slightly better than the TAYLOR algorithm. Considering factors such as the hardware system, it is more appropriate to use the CHAN algorithm in this application.

[0120] Furthermore, increasing the number of base stations can further improve the positioning accuracy of the CHAN algorithm. According to the simulation experiment environment, the number of base stations is increased in sequence at the midpoints of each side of the plane rectangle within the positioning range, and different TDOA ranging error values ​​are taken to analyze the positioning performance of the CHAN algorithm with different base station numbers. The results are as follows: Figure 17 shown.

[0121] according to Figure 17 It can be seen from the broken line that the positioning error of the 3-base station positioning system is relatively large. Increasing the number of base stations can indeed improve the positioning accuracy of the CHAN algorithm, but when the number of base stations is more than 4, the improvement in system positioning accuracy is very small. When the TDOA ranging error is controlled within 0.03m, the positioning accuracy of the CHAN algorithm is less affected by the number of base stations, and the RMSE is always below 0.03m. Although the positioning accuracy of the positioning scheme using more than 4 base stations is slightly improved compared to that of 4 base stations, each additional base station will greatly increase the complexity of the hardware system, thereby increasing the manpower and material costs required for the paving process. Therefore, this application comprehensively considers the impact of the number of base stations on positioning accuracy and the needs of paving operations, and determines that it is most appropriate to use 4 base stations for planar positioning of underground targets.

[0122] In summary, in some implementations of the present application, the multi-signal TDOA ranging method specifically adopts the FANG positioning algorithm. Furthermore, the FANG positioning algorithm is based on a four-base station positioning system.

[0123] refer to Figure 18 In this application, the column-leveling hydraulic system is used to quickly and stably adjust the height of the four column cylinders. The column-leveling hydraulic system includes a hydraulic pump 501, an oil filter 502, an oil tank 503, a safety valve 504, a diverter valve 505, an electro-hydraulic servo valve 506, and a hydraulic lock 507. The four column cylinders include a pair located at the front of the frame and a pair located at the rear of the frame. In each pair, one column cylinder is located on the left side of the frame and the other on the right side, and the two column cylinders are aligned in front and back positions. The four column cylinders are supplied with oil through a hydraulic oil source, which is connected to the oil inlets of two diverter valves; each diverter valve is provided with two oil outlets, corresponding to a pair of column cylinders; the oil outlets of the diverter valves correspond one-to-one to the column cylinders, and a control oil circuit is provided between the two; a hydraulic lock and an electro-hydraulic servo valve for controlling the extension and retraction of the column cylinders are provided on the control oil circuit.

[0124] Column cylinder 2 utilizes an asymmetric piston-type, double-acting hydraulic cylinder. The cylinder barrel is fixedly connected to the frame, while one end of the piston rod is vertically fixed to the paver's crawler chassis. Controlling the hydraulic system's oil flow controls the vertical movement of the cylinder barrel, along with the frame, to achieve leveling. An electro-hydraulic servo valve 506 precisely controls the vertical movement of column cylinder 2. When the actual elevation of column cylinder 2 deviates from the theoretical elevation, a position elevation deviation signal is generated. This deviation signal, via a proportional amplifier and controller, drives the valve core of electro-hydraulic servo valve 506 to move left and right, adjusting the oil flow into column cylinder 2 and, in turn, the vertical movement of the frame barrel. Due to the weight of the paver, column cylinder 2 automatically moves downward during paving operations due to the pressure from the frame. This hydraulic system incorporates a hydraulic lock 507, based on the principle of a one-way valve, to prevent oil from escaping from the hydraulic cylinder during stable operation, maintaining the paver at a constant height. A safety valve 504 provides a pressure stabilizer, ensuring that the operating pressure does not exceed the rated pressure. The function of the diverter valve 505 is to ensure that the flow rates of the oil cylinder branches of each column are equal and to maintain a stable movement speed during the leveling process.

[0125] The hydraulic system power actuators, which are mainly composed of electro-hydraulic servo valves and hydraulic cylinders, are the core of the entire hydraulic control system. The control performance of the power actuators directly affects the working performance of the entire hydraulic leveling system.

[0126] refer to Figure 19 , Figure 19 This is the schematic diagram of the valve-controlled asymmetric hydraulic cylinder. Figure 18 The specific parameters are: A1, A2—the effective area of ​​the rodless and rod chambers of the column cylinder, p1, p2—the pressure of the rodless and rod chambers of the column cylinder, q1, q2—the oil inlet and return flow rates of the column cylinder, x P —Displacement of column cylinder, x v —Electro-hydraulic servo valve spool displacement, p S —Oil inlet pressure of electro-hydraulic servo valve.

[0127] The piston rod of the column cylinder is the fixed end, and the frame is fixedly connected to the cylinder barrel of the column cylinder. The height of the cylinder barrel is adjusted by hydraulic drive, thereby adjusting the position of the floating frame. Here, the mass of the frame can be equivalent to the fixed load force and fixed inertial mass applied to the column cylinder. The structure of the electro-hydraulic servo valve is an ordinary four-way slide valve structure. After omitting other components, the working structure of the valve-controlled asymmetric hydraulic cylinder can be obtained as follows Figure 19As shown. This application uses a double-acting asymmetric hydraulic cylinder. When the paver performs the rising and lowering leveling action, the leveling movement speed of the hydraulic cylinder and the oil pressure and flow rate in the upper and lower chambers are different. The difference between the two execution processes has a significant impact on the accurate establishment of the mathematical model of the control system. It is not possible to adopt a compromise approach and simply establish a simplified control model. Different processes must be analyzed independently. In order to facilitate the mathematical modeling of the valve-controlled asymmetric hydraulic cylinder, the following system settings need to be made here:

[0128] 1) The electro-hydraulic servo valve selected for the system is an ideal zero-opening four-way valve.

[0129] 2) The oil inlet pressure of the four-way slide valve remains constant and the return oil pressure is approximately zero.

[0130] 3) The leakage of asymmetric hydraulic cylinders is laminar flow and the oil temperature is constant.

[0131] When the column cylinder barrel rises, oil flows into the rodless chamber and returns to the rod chamber. The system must overcome the forces generated by the fixed load and inertial mass to push the barrel upward. When the column cylinder descends, oil flows into the rod chamber and returns to the rodless chamber. The load and inertial mass act as the driving force, working together with the oil pressure to push the barrel downward. Therefore, the mathematical modeling of the valve-controlled asymmetric hydraulic cylinder needs to be divided into two cases: the process of the piston rod extending and the cylinder barrel rising, and the process of the piston rod retracting and the cylinder barrel descending.

[0132] During the cylinder rising process, the servo valve linearized flow equation is:

[0133] q L =k q1 x v -k c1 p L

[0134] Among them, k q1 —Flow gain of electro-hydraulic servo valve, that is

[0135] k c1 —Flow pressure coefficient of electro-hydraulic servo valve, that is

[0136] λ1 is the load flow ratio coefficient, C d is the flow coefficient, W is the valve opening area gradient, p S is the oil inlet pressure of the electro-hydraulic servo valve, γ is the ratio of the flow rate out of the hydraulic cylinder to the flow rate into the hydraulic cylinder, p L is the equivalent load pressure, ρ is the hydraulic oil density, x v is the valve core displacement, q L is the load flow.

[0137] During the cylinder rising process, the flow continuity equation of the asymmetric hydraulic cylinder is:

[0138]

[0139] in, is the proportional coefficient, Ae is the average pressure bearing area of ​​the asymmetric cylinder, x P is the displacement of the column cylinder, C tp is the total leakage coefficient of the asymmetric cylinder, V0 is the total initial volume of the hydraulic cylinder when the hydraulic spring stiffness is the smallest, p L is the equivalent load pressure, β e is the effective bulk modulus, and t is the time.

[0140] During the cylinder rising process, the equilibrium equation between the asymmetric cylinder and the load force is:

[0141]

[0142] Among them, A 01 is the equivalent bearing area, m is the equivalent inertial mass, F is the equivalent fixed load force, B P is the viscous damping coefficient, and K is the load spring stiffness.

[0143] The dynamic response characteristics of hydraulic power components are related to the load characteristics, such as Figure 19 As shown in FIG, during the rising process of the cylinder, the load force includes any external load force, inertia force, elastic force and damping force.

[0144] During the cylinder rising process, the transfer function of the system model is:

[0145] Displacement X p The transfer function of the valve core displacement Xv is:

[0146]

[0147] Displacement X p The transfer function of the load force F is:

[0148]

[0149] Among them, ω h1 is the hydraulic natural frequency, ζ h1 is the hydraulic damping ratio, K ce1 is the total flow-pressure coefficient of the system, and s is the Laplace operator.

[0150] During the cylinder descending process, the linearized flow equation of the servo valve is:

[0151] q L =k q2 x v-k c2 p L

[0152] Among them, k q2 —Flow gain of electro-hydraulic servo valve, that is

[0153] k c2 —Flow pressure coefficient of electro-hydraulic servo valve, that is

[0154] Among them, λ2 is the load flow proportional coefficient.

[0155] During the cylinder barrel descending process, the flow continuity equation of the asymmetric hydraulic cylinder is:

[0156]

[0157] in, is the proportional coefficient.

[0158] During the cylinder barrel descending process, the equilibrium equation between the asymmetric cylinder and the load force is:

[0159]

[0160] During the cylinder's descent, the transfer function of displacement Xp to valve core displacement Xv is:

[0161]

[0162] During the cylinder's descent, the displacement X p The transfer function of the load force F is:

[0163]

[0164] Among them, ω h2 is the hydraulic natural frequency, ζ h2 is the hydraulic damping ratio, K ce2 is the total flow-pressure coefficient of the system.

[0165] Furthermore, the initial equilibrium position of the cylinder is related to the stability of the leveling system. When the cylinder system is in different initial equilibrium positions, its dynamic response and stability control performance are quite different. Under large loads, the hydraulic spring stiffness has a very large impact on the stability and rapid response of the valve-controlled cylinder system.

[0166] In the embodiment of the present application, the initial equilibrium position x0 of the column cylinder is set to: Where L is the total stroke of the cylinder piston. Therefore, when the piston is at x0 within the hydraulic cylinder, the hydraulic spring stiffness of the valve-controlled column cylinder system is minimum, allowing the frame to be positioned at this height. The stability control system can then be designed to ensure stable leveling control under all conditions. This position is the initial equilibrium position of the four-column leveling system cylinder.

[0167] In the embodiment of the present application, the column leveling hydraulic system is controlled by PID control, and the transfer function is: Where: Kp is the proportional coefficient, Ki is the integral coefficient, Kd is the differential coefficient; Ti and Td are time constants.

[0168] Fuzzy control is a classic control method in the control field. It is difficult to obtain the best PID control parameters through the above empirical trial and error method. Here we use the fuzzy control algorithm to adaptively adjust the parameters of the PID controller. The input of the fuzzy control system is the deviation of the cylinder elevation e and the elevation deviation change rate ec, and the output is the PID parameters. The three PID parameters Kp, Ki, and Kd are adjusted through fuzzy control. The adjustment formula is: K p =K p0 +K p1 , K i =K i0 +K i1 , K d =K d0 +K d1 Where K p0 , K i0 , K d0 is the initial value of the PID control parameter, and the specific value has been obtained from the above, K p1 , K i1 , K d1 The fuzzy controller outputs the changed value of the parameter, which can be used to adjust the parameter in real time.

[0169] The process of establishing fuzzy rules is generally based on the practical experience of technicians and specialized control theory knowledge. Here, the regulation of the system response by the three links of proportional, integral and differential is determined. The interaction between them is summarized as follows:

[0170] When |e| is large, the system requires good tracking performance, and a larger Kp and a smaller Ki can be used. At this time, in order to avoid excessive overshoot of the system, it is generally necessary to impose certain restrictions on the integral action, such as taking a smaller Kd or setting it to zero.

[0171] When |e| is of medium size, in order to ensure the response speed of the system and control overshoot, Kp should take a smaller value, while Ki and Kd should be of moderate size. Generally, the specific value is determined based on the response situation. Among them, the value of Kd has a greater impact on the system and needs to be determined first.

[0172] When |e| is small, in order to ensure good steady-state control performance of the system, Kp and Ki should take larger values. At the same time, in order to avoid system oscillation and further improve its anti-interference performance, when ec is small, Kd should take a medium value, otherwise Kd should be smaller.

[0173] refer to Figure 20 The present application also provides a 3D leveling device for an underground cement paver, the underground cement paver comprising a crawler chassis, a frame, a trowel plate, and a column cylinder, wherein the frame is connected to the crawler chassis via four column cylinders, the crawler mechanisms on both sides of the crawler chassis each corresponding to two column cylinders, and the column cylinders are telescopically adjustable in height of the frame; the trowel plate is fixedly connected to the frame; the 3D leveling device comprises:

[0174] Position acquisition module 2001, used to obtain the plane position of each column cylinder in real time through indoor wireless positioning method;

[0175] Calculation module 2002, for calculating the theoretical telescopic height corresponding to each column cylinder in real time based on the three-dimensional data of the paving section pavement, the designed paving height of the formed pavement, and the plane position of each column cylinder;

[0176] Determination module 2003, for determining the actual telescopic height of each column cylinder in real time using a height measuring instrument;

[0177] The control module 2004 is used to compare the actual telescopic height with the theoretical telescopic height and output a control signal to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel plate to maintain a preset height and posture during operation.

[0178] The 3D leveling device for the underground cement paver provided in this embodiment corresponds to the 3D leveling method provided in the previous part. For related content, please refer to the content of the previous part and will not be repeated here.

[0179] The specific embodiments described herein are merely illustrative of the spirit of the present application. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present application or exceeding the scope defined by the appended claims.

Claims

1. A 3D leveling method for an underground cement paver, characterized in that: The underground cement paver comprises a crawler chassis, a frame, a trowel plate, and a column cylinder, wherein the frame is connected to the crawler chassis via four column cylinders, the crawler mechanisms on both sides of the crawler chassis each correspond to two column cylinders, and the column cylinders can be telescopically adjusted to adjust the height of the frame; the trowel plate is fixedly connected to the frame; the 3D leveling method comprises: The plane position of each column cylinder is obtained in real time through indoor wireless positioning methods; Based on the 3D data of the paving section, the designed paving height of the formed road surface, and the plane position of each column cylinder, the corresponding theoretical telescopic height of each column cylinder is calculated in real time; Use height measuring instruments to determine the actual telescopic height of each column cylinder in real time; The actual telescopic height is compared with the theoretical telescopic height and a control signal is output to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel to maintain a preset height and posture during operation.

2. The 3D leveling method for an underground cement paver according to claim 1, characterized in that: The wireless positioning method is implemented using a UWB positioning system; The UWB positioning system performs planar positioning of each column cylinder through signal interaction between multiple UWB positioning base stations and positioning tags on each column cylinder.

3. The 3D leveling method for an underground cement paver according to claim 2, characterized in that: The UWB positioning system specifically adopts a multi-signal TDOA ranging method.

4. The 3D leveling method for an underground cement paver according to claim 3, characterized in that: The multi-signal TDOA ranging method specifically adopts the FANG positioning algorithm.

5. The 3D leveling method for an underground cement paver according to claim 4, characterized in that: The FANG positioning algorithm is based on a four-base station positioning system.

6. The 3D leveling method for an underground cement paver according to claim 1, characterized in that: The elevation measuring instrument is implemented using spatial domain laser emission technology; wherein, the spatial domain laser transmitter total station of the elevation measuring instrument is set up at a preset point on the tunnel reference surface, and the laser receiver of the elevation measuring instrument is set on the column cylinder. By receiving signals multiple times, the elevation difference of the laser receiver relative to the laser axis surface can be calculated, thereby obtaining the absolute measurement elevation of the position of the laser receiver.

7. The 3D leveling method for an underground cement paver according to claim 1, characterized in that: The specific steps of comparing the actual telescopic height with the theoretical telescopic height and outputting a control signal to independently control each column cylinder are as follows: The actual telescopic height is compared with the theoretical telescopic height to generate an elevation deviation electrical signal and output it to the hydraulic system of the paver to drive the hydraulic control valve to control the flow and direction of the oil circuit to achieve up and down adjustment of the column cylinder.

8. The 3D leveling method for an underground cement paver according to claim 1, characterized in that: The four column oil cylinders include a pair of column oil cylinders arranged at the front side of the frame and a pair of column oil cylinders arranged at the rear side of the frame; wherein, in each pair of column oil cylinders, one is arranged at the left side of the frame and the other is arranged at the right side of the frame, and the front and rear positions of the two column oil cylinders are consistent; The four column cylinders are supplied with oil through a hydraulic oil source, which is connected to the oil inlets of two diverter valves; each diverter valve is provided with two oil outlets, corresponding to a pair of column cylinders; the oil outlets of the diverter valves correspond one-to-one to the column cylinders, and a control oil circuit is provided between the two; a hydraulic lock and an electro-hydraulic servo valve for controlling the extension and retraction of the column cylinders are provided on the control oil circuit.

9. The 3D leveling method for an underground cement paver according to claim 8, characterized in that: The piston rod of the column cylinder is fixed at the end, and the frame is fixedly connected to the cylinder barrel of the column cylinder. The height of the cylinder barrel, and thus the position of the floating frame, is adjusted by hydraulic drive. When the column cylinder barrel rises, oil enters the rodless chamber of the hydraulic cylinder and oil returns to the rod chamber. The system needs to overcome the force generated by the fixed load force and inertial mass to push the cylinder barrel up. When the column cylinder descends, oil enters the rod chamber of the hydraulic cylinder and oil returns to the rodless chamber. At this time, the load force and inertial mass act as the driving force, and together with the oil pressure, push the cylinder barrel down. During the cylinder rising process, the servo valve linearized flow equation is: q L =k q1 x v -k c1 p L Among them, k q1 —Flow gain of electro-hydraulic servo valve, that is k c1 —Flow pressure coefficient of electro-hydraulic servo valve, that is λ1 is the load flow ratio coefficient, C d is the flow coefficient, W is the valve opening area gradient, p S is the oil inlet pressure of the electro-hydraulic servo valve, γ is the ratio of the flow rate out of the hydraulic cylinder to the flow rate into the hydraulic cylinder, p L is the equivalent load pressure, ρ is the hydraulic oil density, x v is the valve core displacement, q L is the load flow; During the cylinder rising process, the flow continuity equation of the asymmetric hydraulic cylinder is: in, is the proportional coefficient, Ae is the average pressure bearing area of ​​the asymmetric cylinder, x P is the displacement of the column cylinder, C tp is the total leakage coefficient of the asymmetric cylinder, V0 is the total initial volume of the hydraulic cylinder when the hydraulic spring stiffness is the smallest, p L is the equivalent load pressure, β e is the effective bulk modulus, t is the time; During the cylinder rising process, the equilibrium equation between the asymmetric cylinder and the load force is: Among them, A 01 is the equivalent bearing area, m is the equivalent inertial mass, F is the equivalent fixed load force, B P is the viscous damping coefficient, K is the load spring stiffness; The dynamic response characteristics of hydraulic power components are related to the load characteristics. During the rising process of the cylinder, the load force includes any external load force, inertia force, elastic force and damping force; During the cylinder rising process, the transfer function of the system model is: Displacement X p The transfer function of the valve core displacement Xv is: Displacement X p The transfer function of the load force F is: Among them, ω h1 is the hydraulic natural frequency, ζ h1 is the hydraulic damping ratio, K ce1 is the total flow-pressure coefficient of the system, s is the Laplace operator; During the cylinder descending process, the linearized flow equation of the servo valve is: q L =k q2 x v -k c2 p L Among them, k q2 —Flow gain of electro-hydraulic servo valve, that is k c2 —Flow pressure coefficient of electro-hydraulic servo valve, that is Among them, λ2 is the load flow proportional coefficient; During the cylinder barrel descending process, the flow continuity equation of the asymmetric hydraulic cylinder is: in, is the proportionality coefficient; During the cylinder barrel descending process, the equilibrium equation between the asymmetric cylinder and the load force is: During the cylinder's descent, the transfer function of displacement Xp to valve core displacement Xv is: During the cylinder's descent, the displacement X p The transfer function of the load force F is: Among them, ω h2 is the hydraulic natural frequency, ζ h2 is the hydraulic damping ratio, K ce2 is the total flow-pressure coefficient of the system.

10. A 3D leveling device for an underground cement paver, characterized in that: The underground cement paver comprises a crawler chassis, a frame, a trowel plate, and a column cylinder, wherein the frame is connected to the crawler chassis via four column cylinders, the crawler mechanisms on both sides of the crawler chassis each correspond to two column cylinders, and the column cylinders can be telescopically adjusted to adjust the height of the frame; the trowel plate is fixedly connected to the frame; the 3D leveling device comprises: Position acquisition module, used to obtain the plane position of each column cylinder in real time through indoor wireless positioning method; A calculation module is used to calculate the theoretical telescopic height corresponding to each column cylinder in real time based on the three-dimensional data of the paving section pavement, the designed paving height of the formed pavement, and the plane position of each column cylinder; A determination module is used to determine the actual telescopic height of each column cylinder in real time using a height measuring instrument; The control module is used to compare the actual telescopic height with the theoretical telescopic height and output a control signal to independently control each column cylinder so that the actual telescopic height of each column cylinder is always equal to the theoretical telescopic height, thereby allowing the trowel plate to maintain a preset height and posture during operation.

Images