Elevation self-adaptive accurate measurement system for pavement paving

Abstract

The invention relates to the technical field of engineering measurement, in particular to an elevation self-adaptive accurate measurement system for pavement paving, which utilizes mobile nodes, positioning labels and fixed base stations to construct a comprehensive measurement network. By introducing a dynamic threshold value correction module, the system can intelligently identify and cope with a sheltered area, and further activate a cruise measurement mode of the mobile node. In the mode, the unmanned aerial vehicle serves as a mobile node and carries an RIS reflecting surface to conduct circumferential cruise, a propagation channel is effectively reconstructed, and the stability of electromagnetic signals in a shielding area is enhanced. And the system adopts a TDOA positioning algorithm to accurately calculate the position coordinates of the positioning labels, so that the positioning accuracy is further improved. In conclusion, the method not only solves the problem of unstable signal propagation in the sheltered area, but also optimizes the setting of the sheltering threshold value through the adaptive algorithm, so that the system can adapt to different construction environments more flexibly.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering surveying, and particularly to an elevation self-adaptive precise measurement system for road surface paving. Background Art

[0002] During the road surface construction process, the traditional construction method for the water-stable layer and the lower asphalt layer uses the wire-hanging method, and the balance beam method is used for the middle and upper asphalt layers. The traditional construction method has disadvantages such as a large number of auxiliary workers and poor control accuracy. At the same time, the large fluctuation of the road surface thickness uniformity has always been a difficult problem during the road surface construction process, and the variability of the road surface thickness is also one of the important reasons affecting driving comfort and causing early damage to the road surface. Therefore, in the road surface paving project, the precise measurement system is crucial for ensuring the construction quality and progress. However, the traditional measurement methods are often limited by environmental factors, especially in the occlusion area, where the electromagnetic signal propagation is blocked, resulting in a significant decrease in the positioning accuracy. Therefore, there is an urgent need for a road surface paving elevation measurement system that can maintain stable signal transmission and high-precision positioning in a complex construction environment. Summary of the Invention

[0003] The technical problem solved by the present invention is to provide an elevation self-adaptive precise measurement system for road surface paving to solve the technical problem that the traditional measurement method is limited by environmental factors, and the electromagnetic signal propagation is blocked in the occlusion area, resulting in a significant decrease in the positioning accuracy.

[0004] The basic solution provided by the present invention: An elevation self-adaptive precise measurement system for road surface paving includes mobile nodes, positioning tags installed on both sides of the paver, and a number of fixed base stations arranged along the paving direction;

[0005] The positioning tag is an electromagnetic induction positioning tag for transmitting electromagnetic signals received and identified by the fixed base station;

[0006] The fixed base station includes a signal strength analysis module, a dynamic threshold correction module, and a three-dimensional positioning module; after the fixed base station receives the electromagnetic signal transmitted by the positioning tag, the three-dimensional positioning module synchronously calculates the position coordinates of the positioning tag including the horizontal coordinate and the elevation coordinate according to the received electromagnetic signal strength value and the propagation delay data; the dynamic threshold correction module presets an occlusion threshold When the change in the intensity of the continuously received electromagnetic signal reaches the occlusion threshold It is determined that the paver travels to the occlusion area, and the cruise measurement mode of the mobile node is triggered;

[0007] The mobile node uses a drone, and a RIS reflector is mounted on the bottom of the drone. The mobile node starts a circular cruise mode in the occlusion area. The mobile node establishes a polar coordinate system with the occlusion area as the center point in the circular cruise mode, and performs spiral climbing flight along a circle with a radius of 3 - 5 m. The flight height change gradient is 0.2 - 0.5 m / turn. The electromagnetic signal propagation channel is reconstructed through the RIS reflector mounted on the bottom to improve the stability of the electromagnetic signal propagation in the occlusion area.

[0008] Further, the occlusion threshold of the dynamic threshold correction module adopts an adaptive algorithm:

[0009]

[0010] In the formula, k = 0.2 dB / s, the reference threshold is dynamically adjusted according to the historical signal strength variance:

[0011]

[0012] In the formula, σ is the RSSI standard deviation in the previous ten minutes. When the signal strength fluctuates by more than within 5 consecutive seconds, the occlusion determination is triggered. Further, the fixed base station uses the TDOA positioning algorithm to calculate the position coordinates of the positioning tag:

[0013] Δt ij =(d i -d j ) / c

[0014] In the formula, d i , d j respectively represent the distances from the positioning tag to the i-th and j-th fixed base stations, c is the electromagnetic wave propagation speed, and the three-dimensional coordinate solution value is obtained by solving the nonlinear equation system.

[0015] Further, the fixed base stations are linearly arranged at intervals of 50 - 80 m along the paving direction. Each base station is equipped with a dual-band receiving antenna array, and this antenna array consists of 4 groups of directional antennas distributed in a cross shape. The adjustable range of the antenna elevation angle is 15° - 75°.

[0016] Further, in the circular cruise mode of the mobile node, the cruise radius R satisfies:

[0017]

[0018] In the formula, h is the current flight height, and θ min ≥30° is the minimum elevation angle constraint.

[0019] Further, the housing of the positioning tag is made of a copper mesh-ceramic composite structural material.

[0020] The principle and advantages of the present invention are as follows: The present invention proposes an elevation self - adaptive precise measurement system, which constructs a comprehensive measurement network by using mobile nodes, positioning tags, and fixed base stations. By introducing a dynamic threshold correction module, the system can intelligently identify and cope with occlusion areas, and then activate the cruise measurement mode of the mobile nodes. In this mode, the unmanned aerial vehicle (UAV) serves as the mobile node, carrying the RIS reflector for circular cruising, effectively reconstructing the propagation channel, and enhancing the stability of electromagnetic signals in the occlusion area. The system uses the TDOA positioning algorithm to accurately calculate the position coordinates of the positioning tags, further improving the positioning accuracy. In summary, the present invention not only solves the problem of unstable signal propagation in the occlusion area, but also optimizes the setting of the occlusion threshold through an adaptive algorithm, enabling the system to more flexibly adapt to different construction environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of an embodiment of the elevation self - adaptive precise measurement system for road surface paving of the present invention.

[0022] Figure 2 It is a logic block diagram of an embodiment of the elevation self - adaptive precise measurement system for road surface paving of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following is a more detailed description through specific embodiments:

[0024] The specific implementation process is as follows:

[0025] Embodiment 1

[0026] Embodiment 1 is basically as shown in the attached Figure 1 、 Figure 2 An elevation self - adaptive precise measurement system for road surface paving includes mobile nodes, positioning tags installed on both sides of the paver, and several fixed base stations arranged along the paving direction. This system constructs a comprehensive measurement network by using mobile nodes, positioning tags, and fixed base stations. By introducing a dynamic threshold correction module, the system can intelligently identify and cope with occlusion areas, and then activate the cruise measurement mode of the mobile nodes. In this mode, the UAV serves as the mobile node, carrying the RIS reflector for circular cruising, effectively reconstructing the propagation channel, and enhancing the stability of electromagnetic signals in the occlusion area.

[0027] In this embodiment, a fixed base station is set every 60 meters along the road surface paving direction. Each base station is equipped with a dual - band receiving antenna array, and the antenna array consists of 4 groups of directional antennas distributed in a cross shape. The antenna elevation angle is adjusted to 45°, covering a receiving range of ±60° in the horizontal direction. The base station housing is designed with waterproof and dust - proof features, and the bottom is fixed to the stable foundation outside the construction area through ground nails.

[0028] Two groups of electromagnetic induction positioning tags are symmetrically installed on the frames on both sides of the paver. The tag housing adopts a copper mesh-ceramic composite structure, with a copper mesh layer thickness of 0.5 mm and a ceramic layer thickness of 2 mm to shield mechanical vibration interference in the construction environment. The tag operates in a dual-frequency emission mode of 2.4 GHz and 5.8 GHz, and the signal emission interval is 10 ms.

[0029] Specifically, the fixed base station in this embodiment includes a signal strength analysis module, a dynamic threshold correction module, and a three-dimensional positioning module; after the fixed base station receives the electromagnetic signal emitted by the positioning tag, the three-dimensional positioning module synchronously calculates the position coordinates of the positioning tag including horizontal coordinates and elevation coordinates based on the received electromagnetic signal strength value and propagation delay data; the fixed base station in this embodiment uses the TDOA positioning algorithm to calculate the position coordinates of the positioning tag:

[0030] Δt ij =(d i -d j ) / c

[0031] In the formula, d i , d j respectively represent the distances from the positioning tag to the i-th and j-th fixed base stations, c is the electromagnetic wave propagation speed, and the three-dimensional coordinate solution value is obtained by solving the nonlinear equation system.

[0032] For example, between base station 1 and base station 2, the distance difference from the positioning tag to each base station is calculated through the signal propagation delay:

[0033] The time delay difference Δt 12 between base station and base station 2 =(d1 - d2) / c, where c = 3×10 8 m / s. By solving the nonlinear equation system:

[0034]

[0035] The three-dimensional coordinates (x, y, z) of the positioning tag are calculated iteratively using the least squares method.

[0036] The dynamic threshold correction module presets an occlusion threshold When the change in the intensity of continuously received electromagnetic signals reaches the occlusion threshold , it is determined that the paver has traveled to the occlusion area, triggering the cruise measurement mode of the mobile node. For example, if the signal intensity change rate is , the trigger threshold is 6 + 0.2×10 = 8 dB. Among them, the occlusion threshold of the dynamic threshold correction module adopts an adaptive algorithm:

[0037]

[0038] where k = 0.2 dB / s, the reference threshold Dynamically adjusted according to the variance of historical signal strength:

[0039]

[0040] where σ is the RSSI standard deviation in the previous ten minutes. When the signal strength fluctuates by more than within 5 consecutive seconds, the occlusion determination is triggered. For example, during the progress of the paver, the fixed base station monitors the RSSI value of the positioning tag in real time. Suppose that within the t-th second to the (t + 5)-th second, the signal strength received by the base station drops suddenly from -65 dBm to -75 dBm (the fluctuation amplitude is 10 dB), exceeding the preset φ = 8 dB. The dynamic threshold correction module determines that the paver enters the occlusion area (such as the area blocked by a bridge pier or construction machinery), and sends a start command to the mobile node.

[0041] In this embodiment, the mobile node uses a drone. The bottom of the drone is equipped with a RIS reflecting surface. After receiving the start signal, the drone starts a circular cruise mode in the occlusion area. In the circular cruise mode of the mobile node, the cruise radius R satisfies:

[0042]

[0043] where h is the current flight altitude, and θ min ≥ 30° is the minimum elevation angle constraint.

[0044] Specifically, after receiving the start command, the mobile node (drone) starts a circular cruise mode with the center point O of the occlusion area as the center. The initial flight altitude of the drone is 5 m, and it starts horizontal circular flight with a radius R = 5 m, while climbing in a gradient spiral at 0.3 m / turn. During the flight, the RIS reflecting surface at the bottom of the drone dynamically adjusts the phase to reconstruct the propagation path of the electromagnetic signal. For example, when the drone climbs to an altitude h = 8 m, the cruise radius is automatically adjusted to R = 8 / tan30° ≈ 13.8 m (θ min = 30°) to ensure the minimum elevation angle constraint of the signal reflection path.

[0045] The RIS reflecting surface of the drone in this embodiment is composed of 256 adjustable units. During the cruise, it can dynamically adjust the reflection phase according to the signal strength distribution feedback by the base station. For example, when the base station detects that the signal incident angle is θ = 50°, the RIS reflecting surface generates a beamforming matrix to adjust the reflection signal direction to θ' = 30°, bypassing the occlusion and reaching the base station directly, so as to improve the signal strength.

[0046] In summary, the present system constructs a comprehensive measurement network using mobile nodes, positioning tags, and fixed base stations. By introducing a dynamic threshold correction module, the system can intelligently identify and respond to occluded areas, thereby activating the cruise measurement mode of the mobile nodes. In this mode, the unmanned aerial vehicle serves as a mobile node, carrying a RIS reflector for circular cruising, effectively reconstructing the propagation channel and enhancing the stability of electromagnetic signals in the occluded area. The system uses the TDOA positioning algorithm to accurately calculate the position coordinates of the positioning tags, further improving the positioning accuracy. In summary, the present invention not only solves the problem of unstable signal propagation in occluded areas but also optimizes the setting of the occlusion threshold through an adaptive algorithm, enabling the system to more flexibly adapt to different construction environments.

[0047] The above are only embodiments of the present invention. Specific structures and common knowledge such as characteristics that are well-known in the art are not described in detail here. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the existing technologies in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can still be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to explain the content of the claims.

Claims

1. An elevation self-adaptive precise measurement system for road surface paving, characterized in that: It includes mobile nodes, positioning tags installed on both sides of the paver, and several fixed base stations arranged along the paving direction; The positioning tag is an electromagnetic induction type positioning tag, which is used to emit electromagnetic signals received and identified by the fixed base station; The fixed base station includes a signal strength analysis module, a dynamic threshold correction module, and a three-dimensional positioning module. After receiving the electromagnetic signal transmitted by the positioning tag, the three-dimensional positioning module synchronously calculates the position coordinates of the positioning tag, including the horizontal coordinates and elevation coordinates, according to the received electromagnetic signal strength value and propagation delay data. The dynamic threshold correction module presets an occlusion threshold When the change in the continuously received electromagnetic signal strength reaches the occlusion threshold it is determined that the paver has traveled to the occluded area, triggering the cruise measurement mode of the mobile node; The mobile node uses a drone. The bottom of the drone is equipped with a RIS reflector. The mobile node turns on the circumferential cruise mode in the occlusion area. The mobile node establishes a polar coordinate system with the occlusion area as the center point in the circumferential cruise mode, and performs spiral climbing flight along a circle with a radius of 3-5m. The flight height change gradient is 0.2-0.5m / turn. The electromagnetic signal propagation channel is reconstructed through the RIS reflector carried at the bottom to improve the stability of the electromagnetic signal propagation in the occlusion area.

2. The height self-adaptive precise measurement system for road surface paving according to claim 1, characterized in that: The occlusion threshold of the dynamic threshold correction module Adopt an adaptive algorithm: where k = 0.2 dB / s, the reference threshold Dynamically adjusted according to the variance of historical signal strength: Where σ is the RSSI standard deviation in the first ten minutes, and occlusion determination is triggered when the signal strength fluctuates by more than within 5 consecutive seconds.

3. The height self-adaptive precise measurement system for road surface paving according to claim 2, characterized in that: The fixed base station uses the TDOA positioning algorithm to calculate the position coordinates of the positioning tag: Δt ij =(d i -d j ) / c where d i and d j represent the distances from the positioning tag to the i-th and j-th fixed base stations respectively, c is the electromagnetic wave propagation speed, and the three-dimensional coordinate solution value is obtained by solving the non-linear equations.

4. An elevation self - adapting precise measurement system for road surface paving according to claim 3, characterized in that: The fixed base stations are linearly arranged at intervals of 50-80m along the paving direction. Each base station is equipped with a dual-band receiving antenna array, which is composed of 4 groups of directional antennas distributed in a cross shape. The adjustable range of the antenna elevation angle is 15°-75°.

5. The elevation self-adaptive precise measurement system for pavement paving according to claim 4, characterized in that: When the mobile node is in the circumferential cruise mode, the cruise radius R satisfies: where h is the current flight altitude, and θ min ≥ 30° is the minimum elevation angle constraint.

6. The elevation self - adaptive precise measurement system for road surface paving according to claim 5, characterized in that: The outer shell of the positioning tag is made of a copper mesh-ceramic composite structural material.

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