Measurement method for high-precision measurement of bridge pier based on flight displacement measurement robot

Abstract

The invention relates to the technical field of building engineering structure measurement positioning and recognition, and discloses a high-precision pier measurement method based on a flight displacement measurement robot, and the method comprises the steps: controlling a remote control terminal to enable an unmanned plane to fly to a target pier, and carrying a posture adjustment mechanism and a measurement rod on the unmanned plane; recognizing the contour of the target pier through an image processing algorithm, calculating the center point coordinate of the target pier, and controlling the unmanned aerial vehicle to hover right above the center point coordinate; after the unmanned aerial vehicle lands, the attitude of the measuring rod is adjusted by using the attitude adjusting mechanism; the ground measurement auxiliary equipment and the measurement rod are matched for use, and multi-dimensional measurement is carried out on the target pier; after the measurement is completed, executing a next flight command, and measuring a next target pier; after all target piers are measured, the unmanned aerial vehicle returns; and analyzing measured data. According to the invention, the precision, efficiency and safety of pier top measurement are improved through an automatic means, and the high-standard requirements of modern bridge engineering are met.

Description

Technical Field

[0001] The present invention relates to the technical field of measurement, positioning and identification of construction engineering structures, and in particular to a measurement method for high-precision measurement of bridge piers based on a flying displacement measurement robot. Background Art

[0002] In bridge construction and maintenance, accurate measurement of bridge piers is crucial for ensuring structural safety and construction quality. Traditional pier measurement methods rely primarily on manual labor, requiring workers to climb to the top of the pier or utilize climbing equipment (such as hanging baskets and scaffolding) for contact measurement, using tools such as measuring rods and total stations to collect data point by point.

[0003] However, this traditional method has the following significant defects: the high-altitude working environment is complex, personnel need to operate on the top of the bridge pier, the space is narrow, and they face safety risks such as falling from height and equipment instability. Especially in severe weather or complex terrain conditions, the accident rate increases significantly, and the top of the bridge pier often has complex environments such as uneven ground, obstacles or water. Traditional equipment is difficult to set up stably, and the plumbness and positioning accuracy of the measuring rod are difficult to guarantee. Manual operation is difficult to ensure high-precision measurement and is easily affected by subjective factors. It is difficult to meet the strict requirements of modern bridge engineering for measurement accuracy and efficiency. Summary of the Invention

[0004] The present invention provides a high-precision measurement method for bridge piers based on a flying displacement measuring robot, thereby solving the technical problems in the prior art of manual operation on the top of the pier, difficulty in ensuring the plumbness and positioning accuracy of the measuring rod, and low measurement efficiency for countless piers. The invention improves the accuracy, efficiency and safety of measurement on the top of the pier through automated means, meeting the high standards required for modern bridge engineering.

[0005] The present invention provides a measurement method for high-precision measurement of bridge piers based on a flying displacement measurement robot, comprising: controlling a remote control terminal to make a drone fly toward a target bridge pier, the drone being equipped with a posture adjustment mechanism and a measuring rod, the posture adjustment mechanism being used to adjust the posture of the measuring rod; collecting an image of the top of the target bridge pier by a camera carried by the drone, identifying the outline of the target bridge pier and calculating its center point coordinates by using an image processing algorithm, and controlling the drone to hover directly above the center point coordinates; after the drone lands, adjusting the posture of the measuring rod by using the posture adjustment mechanism, so that the measuring rod remains vertical and accurately aligned with the center of the target bridge pier; performing multi-dimensional measurement of the target bridge pier by using ground measurement auxiliary equipment in combination with the measuring rod; after the measurement is completed, executing the next flight command to measure the next target bridge pier; after the measurement of all target bridge piers is completed, the drone returns; and analyzing the measurement data of all target bridge piers.

[0006] Furthermore, the steps of the UAV identifying the outline of the target pier and calculating the center point coordinates for hovering and landing include: the UAV is equipped with a high-resolution camera, hovering above the target pier, collecting a bird's-eye view image of the target pier, and there are four pad stones on the top surface of the target pier; using a pre-trained deep learning model to analyze the bird's-eye view image, and the model outputs the geometric center coordinate values of the four pad stones; the geometric center coordinate values of the pad stones output by the model are compared with the geometric center values of the designed pad stones. If the comparison is consistent, the center point coordinates of the target pier are calculated using the four pad stone geometric center coordinates. If the comparison is inconsistent, a pad stone construction deviation warning is sent; after the comparison is consistent, the center point coordinates of the target pier are fed back to the UAV flight control system, the UAV hovering position is adjusted, and the deviation between the UAV and the center point coordinates is monitored in real time, so that the UAV can land accurately; after the UAV completes landing, the center point coordinate data of the target pier is stored to provide a reference for subsequent measurement or construction tasks.

[0007] Furthermore, the step of using the posture adjustment mechanism to adjust the posture of the measuring rod includes: using the lateral and longitudinal displacement sensors at the bottom of the measuring rod to sense the position of the measuring rod, and comparing it with the center point coordinates of the target pier contour to calculate the center point offset; the XY direction fine-tuning component in the posture adjustment mechanism moves the position of the measuring rod according to the center point offset, and corrects the planar position of the measuring rod so that the measuring rod is at the center point coordinates of the pier; the Z direction fine-tuning component in the posture adjustment mechanism corrects the plumbness of the measuring rod based on the gyroscope data feedback at the bottom of the measuring rod, so that the measuring rod remains vertical.

[0008] Furthermore, the Z-direction fine-tuning component includes an electric push rod and a gyroscope angle feedback closed-loop control, and the verticality adjustment accuracy is ≤0.5 degrees.

[0009] Furthermore, the XY direction fine-tuning component drives the screw through a micro motor, so that the measuring rod can be accurately displaced within the range of ±5cm in the horizontal plane.

[0010] Furthermore, the method for the drone to fly above the top of the target bridge pier is as follows: the pier image is collected by the stereo vision system carried by the drone, the pier outline is identified using the improved Canny edge detection algorithm and SURF feature extraction algorithm, and the three-dimensional spatial coordinates of the pier are generated in combination with the three-dimensional reconstruction technology. The drone automatically locates the top of the target bridge pier.

[0011] Furthermore, the improved Canny edge detection algorithm uses bilateral filter instead of Gaussian filter and adds gradient direction calculation.

[0012] Furthermore, the ground measurement auxiliary equipment includes a total station and a laser receiver. A prism and a laser rangefinder are set on the measuring rod. The total station is used to cooperate with the prism on the measuring rod, and the laser receiver is used to cooperate with the laser rangefinder on the measuring rod.

[0013] One or more technical solutions provided in the present invention have at least the following technical effects or advantages:

[0014] By using drones equipped with measuring rods and attitude adjustment mechanisms, combined with visual recognition algorithms and ground measurement equipment, high-precision measurement, automation, intelligence and high safety of bridge piers are achieved. The entire measurement process does not require human intervention, and drones can be used to fly efficiently to countless target piers, greatly improving measurement efficiency. This solves the technical problem of manual operation on the top of the pier in the existing technology, making it difficult to ensure the plumbness and positioning accuracy of the measuring rod, and resulting in low measurement efficiency, thereby meeting the stringent requirements of modern bridge engineering for measurement accuracy and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of various stages of a method for high-precision measurement of bridge piers based on a flying displacement measurement robot in an embodiment of the present invention;

[0016] Figure 2 A schematic diagram of the process of bridge pier image acquisition and recognition and center point coordinate calculation in an embodiment of the present invention;

[0017] Figure 3 This is a top view of a bridge pier in an embodiment of the present invention, mainly illustrating the structure of the pad stone; DETAILED DESCRIPTION

[0018] In order to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0019] Reference Figure 1 The measurement method of bridge piers with high precision based on the flying displacement measuring robot includes five stages: preparation stage, UAV visual coarse positioning stage, measuring rod mechanical fine adjustment stage, total station measurement stage, operation completion stage, and measurement data analysis stage.

[0020] Preparation stage

[0021] The preparation phase involves a comprehensive inspection and preparation of the drone and its onboard measuring equipment before the measurement mission begins, ensuring proper system operation and measurement accuracy. This phase includes drone inspection, installation and calibration of the measuring rod, and environmental assessment.

[0022] Drone inspections include:

[0023] Battery power: Ensure that the drone battery has sufficient power to support the flight and operation of the entire measurement mission. There may be more than one bridge pier to be measured. It is recommended to keep the battery power at 100% and carry a spare battery to deal with emergencies.

[0024] Camera calibration: Check the high-resolution camera on the drone to ensure its clarity and focus function, and perform camera calibration to ensure the accuracy of image acquisition.

[0025] Sensor calibration: Prisms, laser rangefinders, Beidou receivers and other instruments are installed on the measuring rod. Transverse and longitudinal displacement sensors are also installed on the bottom of the measuring rod to sense the position of the measuring rod. The above instruments and sensors are calibrated to ensure the accuracy of their feedback data.

[0026] Flight control system check: Check the drone's flight control system to ensure that sensors such as the Beidou module and inertial measurement unit (IMU) are working properly and that the drone can achieve precise hovering and positioning.

[0027] Measuring rod installation and calibration includes:

[0028] Install the measuring rod onto the attitude adjustment mechanism on the drone, ensuring a secure connection.

[0029] Perform a preliminary calibration of the plumbness of the measuring rod to ensure that it remains as vertical as possible in the unadjusted state.

[0030] Environmental assessments include:

[0031] Before the operation, the target bridge pier and its surrounding environment should be assessed to ensure that there are no obstacles in the drone's flight path. Pay special attention to obstacles such as high-voltage power lines and trees that may affect the drone's flight.

[0032] Assess weather conditions and ensure that environmental factors such as wind speed and light are within the operational range of the drone. It is recommended to conduct measurement operations under conditions with wind speeds below level 5 and sufficient light.

[0033] UAV visual coarse positioning stage

[0034] The purpose of the drone's visual coarse positioning phase is to control the drone to fly to the target bridge pier after completing preparatory work, collect images of the pier's top, calculate the coordinates of the center point, and finally land the drone to initially position the measuring rod at the center of the pier. The drone's visual coarse positioning phase includes drone takeoff, pier image acquisition and recognition, center point coordinate calculation, drone landing, and data storage and transmission.

[0035] The drone takes off: Based on a preset route, it autonomously flies to the vicinity of the target bridge pier, maintaining a safe distance. Its onboard high-precision stereo vision system simultaneously collects multi-view image data of the pier. It employs an improved Canny edge detection algorithm, replacing the traditional Gaussian filter with bilateral filtering to optimize noise suppression and enhance the accuracy of gradient direction calculations. Combined with the SURF feature extraction algorithm, it accurately identifies the pier's outline. Based on multi-view geometry principles, it uses feature point matching and triangulation calculations to reconstruct the pier's three-dimensional spatial coordinates in real time. It also automatically locates key measurement points on the pier's top, establishing a reference coordinate system for subsequent measurement operations. The entire recognition process incorporates an adaptive illumination compensation mechanism to ensure detection stability in diverse environments.

[0036] Bridge pier image acquisition and recognition and center point coordinate calculation, such as Figure 2 As shown, the following steps are included:

[0037] S1, Image acquisition and preprocessing.

[0038] The UAV is equipped with a high-resolution camera and hovers above the target pier to collect the top view image of the target pier, mainly collecting the part containing the four pad stones (such as Figure 3 As shown), the four pads on the target pier play an important role in the construction of the bridge. The pier pads play an important role in load transfer, height adjustment, shock absorption, maintenance, deformation adaptation and corrosion prevention, ensuring the safety and durability of the bridge.

[0039] The image is preprocessed, including denoising, contrast enhancement, grayscale conversion and other operations, to improve the recognition accuracy.

[0040] The visual recognition algorithm carried by the drone has been trained with a large number of image samples with different lighting, weather, and bridge pier types. It has high robustness and accuracy and can work stably under different lighting and weather conditions.

[0041] S2, geometric center calculation.

[0042] A pre-trained deep learning model is used to analyze the top-view image, identify the four corners of each shim's quadrilateral, and calculate the shim's geometric center coordinates. Furthermore, the shim's geometric center coordinates can also be calculated using the shim's four holes.

[0043] S3, comparison result judgment.

[0044] S31, if the geometric center coordinate value of the pad stone output by the model is consistent with the geometric center value of the designed pad stone (within the allowable error range), then proceed to the next step of calculating the center point coordinates of the target pier.

[0045] S32: If the geometric center coordinate value of the pad stone output by the model is inconsistent with the designed geometric center value of the pad stone (exceeds the allowable error range), a pad stone construction deviation warning is sent to prompt the construction personnel to check and adjust.

[0046] S4, center point coordinate calculation.

[0047] In the case of consistency, the geometric center coordinates of the four pad stones are used to calculate the center coordinates of the target pier.

[0048] S5, drone hovering adjustment.

[0049] The calculated coordinates of the center point of the target bridge pier are fed back to the UAV's flight control system. The flight control system adjusts the UAV's hovering position based on the coordinate values to ensure that the UAV can accurately aim at the center point of the bridge pier.

[0050] Drone landing: The deviation between the coordinates of the drone and the center point of the target bridge pier is monitored in real time. The position of the drone is continuously adjusted through the feedback mechanism of the flight control system to ensure that the deviation between the drone and the center point is minimized during hovering and landing.

[0051] Data storage and transmission: After the drone lands, it stores the center point coordinate data of the target bridge pier and can transmit the center point coordinate data to the ground to provide a reference for subsequent measurement or construction tasks.

[0052] Mechanical fine adjustment stage of the measuring rod

[0053] The purpose of the mechanical fine adjustment phase of the measuring rod is to use the attitude adjustment mechanism on the drone to adjust the measuring rod's attitude, so that the measuring rod remains vertical and precisely aligned with the center of the target bridge pier. The measuring rod attitude adjustment phase includes adjusting the measuring rod's plane position and plumbness.

[0054] Measuring rod plane position adjustment: Horizontal and vertical displacement sensors at the base of the measuring rod detect its position and compare it with the center coordinates of the pier contour to calculate the center offset. The XY fine-tuning assembly within the attitude adjustment mechanism moves the measuring rod based on this center offset. A micromotor-driven screw drive precisely shifts the measuring rod within a ±5 cm horizontal plane, correcting its plane position and ensuring it is positioned at the center coordinates of the pier.

[0055] Plumb Adjustment: The Z-axis fine-tuning component in the attitude adjustment mechanism uses gyroscope data from the base of the rod to correct the rod's plumbness. This component incorporates a motorized actuator and gyroscope angle feedback in a closed-loop control system. The Z-axis fine-tuning component provides a plumb adjustment accuracy of ≤0.5 degrees, ensuring the rod remains vertical.

[0056] Total station measurement phase

[0057] The measurement phase involves the use of ground-based measurement equipment and surveying rods to achieve multi-dimensional measurements of the target bridge piers. The total station measurement phase includes total station setup, surveying rod prism alignment and measurement, and total station measurement data transmission and storage.

[0058] Total station setup: Place the total station on the survey station, adjust the height using the tripod, use the optical plummet or laser plummet function to ensure that the center of the instrument is accurately aligned with the survey station, and adjust the bubble center using the foot screws to achieve leveling.

[0059] Prism aiming and measurement on the measuring rod: Rotate the telescope to accurately aim at the center of the prism, and ensure that the vertical wire of the crosshairs coincides with the prism on the measuring rod to reduce errors; the total station is used to cooperate with the prism on the measuring rod, the laser receiver is used to cooperate with the laser rangefinder on the measuring rod, and the Beidou measurer cooperates with the Beidou receiver on the measuring rod; according to the requirements of the measurement task, the Z-axis adjustment mechanism controls the measuring rod to move up and down to the specified measurement height, and the prism at the top of the measuring rod cooperates with the total station on the ground to measure the height and plumbness of the bridge pier; the laser rangefinder at the bottom of the measuring rod cooperates with the laser receiver on the ground to measure the distance between the bridge pier and the ground; the Beidou receiver on the measuring rod cooperates with the Beidou measurer on the ground to measure the precise geographical location of the bridge pier.

[0060] Total station measurement data transmission and storage: Measurement data is automatically stored in the instrument memory, named by project classification, and sent to the terminal device according to the protocol.

[0061] Job completion stage

[0062] The operation completion phase includes retrieving the measuring rod, executing the next flight command, and returning the UAV.

[0063] Measuring rod retraction: After the measurement is completed, the measuring rod is retracted to its initial position to ensure that the measuring rod does not interfere with the flight during the drone's return.

[0064] Execute the next flight command: When there are multiple bridge piers to be measured, after the measurement of the bridge pier is completed, the measurement command of the next bridge pier is executed, so that the UAV automatically flies to the vicinity of the next bridge pier. The flight control system calculates the optimal route, considering the following factors: shortest flight path, obstacle avoidance, and measurement angle requirements. After arriving at the target location, it automatically executes the same standardized measurement process as the first bridge pier.

[0065] Drone Return: Assuming sufficient battery life, the drone will survey all target bridge piers, then take off and return to the designated landing point. If the battery level runs low during the measurement process, the drone can be controlled to return. During the return process, the drone's flight status is monitored in real time to ensure a safe landing. All automated flight processes feature a manual override interface, allowing the operator to take over control at any time. The battery safety threshold is adjusted before each mission based on actual distance and weather conditions.

[0066] Measurement data analysis phase

[0067] The measurement data is transmitted to the terminal device, and the staff can analyze and process the measurement data through the ground control station software to generate an accurate measurement report of the bridge pier.

[0068] The present invention's method for high-precision measurement of bridge piers based on a flying displacement measuring robot achieves high-precision measurement of bridge piers, automation and intelligence, high safety, and efficient measurement of multiple bridge piers through the combination of drones, visual recognition algorithms, attitude adjustment mechanisms, and ground measurement equipment.

[0069] High-precision measurement: The drone's high-resolution camera and pre-trained deep learning model enable the rapid and accurate identification of pier outlines and calculation of their center coordinates. Combined with the XY and Z fine-tuning components of the attitude adjustment mechanism, the measuring rod can be precisely adjusted in the horizontal and vertical directions, ensuring that it is always at the center of the pier and remains vertical. The laser rangefinder, prism, and other equipment at the bottom of the measuring rod work in conjunction with ground-based measurement auxiliary equipment (such as total stations and laser receivers) to achieve precise measurement of multiple dimensions, including pier height, plumbness, and geographic location. The measurement accuracy reaches the millimeter level, meeting the stringent measurement accuracy requirements of modern bridge engineering.

[0070] Automation and Intelligence: This method achieves automation and intelligent measurement through the collaborative work of the drone's flight control system, visual recognition algorithms, and attitude adjustment mechanisms. The drone is capable of autonomous flight, hovering, and landing, and automatically locates the center of the bridge pier using a visual recognition algorithm. The attitude adjustment mechanism automatically adjusts the position and plumbness of the measuring rod based on sensor data, ensuring it remains in optimal measurement conditions. The entire measurement process requires no human intervention, significantly improving measurement efficiency and reducing human error.

[0071] High Safety: Traditional bridge pier measurement requires manual climbing to the top of the pier or operating in complex terrain, which carries significant safety risks. This method, which uses drones equipped with measuring rods, eliminates manual overhead work and significantly reduces safety risks for operators. This is particularly true during the initial stages of bridge construction or maintenance, when the environment around piers is complex. Drones can easily handle these complex terrains, ensuring safe measurement operations.

[0072] Efficient measurement of multiple piers: Once the measurement of one target pier is completed, the measurement command for the next pier can be quickly executed without manually moving the measuring rod to different piers, greatly improving measurement efficiency.

[0073] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

[0074] The above is only a preferred specific implementation of the embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with this technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solutions and concepts of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A high-precision measurement method for bridge piers based on a flying displacement measurement robot, including: The remote control terminal is controlled to make the UAV fly towards the target bridge pier. The UAV is equipped with an attitude adjustment mechanism and a measuring rod. The attitude adjustment mechanism is used to adjust the attitude of the measuring rod. The camera onboard the drone captures images of the top of the target pier, uses image processing algorithms to identify the outline of the target pier and calculate the coordinates of its center point, and controls the drone to hover directly above the coordinates of the center point. After the drone lands, the attitude adjustment mechanism is used to adjust the attitude of the measuring rod so that the measuring rod remains vertical and accurately aligned with the center of the target bridge pier; Through the use of ground measurement auxiliary equipment and measuring rods, multi-dimensional measurement of target bridge piers is carried out; After the measurement is completed, the next flight command is executed to measure the next target bridge pier; After all target piers are measured, the drone returns; The measurement data of all target bridge piers are analyzed.

2. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 1, characterized in that: The steps for the drone to identify the target pier outline and calculate the center point coordinates for hovering and landing include: The drone, equipped with a high-resolution camera, hovered above the target bridge pier to collect a bird's-eye view of the target pier, which has four pad stones on its top surface. The pre-trained deep learning model is used to analyze the overhead image, and the model outputs the coordinates of the geometric centers of the four pad stones; Compare the geometric center coordinates of the pad stone output by the model with the geometric center coordinates of the designed pad stone. If the comparison is consistent, the center coordinates of the target pier are calculated using the geometric center coordinates of the four pad stones. If the comparison is inconsistent, a pad stone construction deviation warning is issued; After the comparison is consistent, the center point coordinates of the target bridge pier are fed back to the UAV flight control system, the UAV hovering position is adjusted, and the deviation between the UAV and the center point coordinates is monitored in real time to ensure the UAV lands accurately. After the drone completes landing, it stores the center point coordinate data of the target bridge pier to provide a reference for subsequent measurement or construction tasks.

3. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 1, characterized in that: The steps of adjusting the posture of the measuring rod by the posture adjustment mechanism include: The horizontal and vertical displacement sensors at the bottom of the measuring rod are used to sense the position of the measuring rod and compare it with the center point coordinates of the target pier contour to calculate the center point offset. The XY direction fine adjustment component in the posture adjustment mechanism moves the position of the measuring rod according to the center point offset, corrects the plane position of the measuring rod, and makes the measuring rod be at the center point coordinate of the bridge pier; The Z-direction fine-tuning component in the attitude adjustment mechanism corrects the verticality of the measuring rod based on the gyroscope data feedback at the bottom of the measuring rod, so that the measuring rod remains vertical.

4. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 3, characterized in that: The Z-direction fine-tuning component includes an electric push rod and a gyroscope angle feedback closed-loop control, and the vertical adjustment accuracy is ≤0.5 degrees.

5. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 3, characterized in that: The XY direction fine-tuning assembly is driven by a micro motor to drive the screw, so that the measuring rod can be accurately displaced within the range of ±5cm in the horizontal plane.

6. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 1, characterized in that: The method for flying a drone to the top of the target bridge pier is as follows: the stereo vision system carried by the drone collects the bridge pier image, uses the improved Canny edge detection algorithm and SURF feature extraction algorithm to identify the bridge pier outline, combines the 3D reconstruction technology to generate the 3D spatial coordinates of the bridge pier, and the drone automatically locates the top of the target bridge pier.

7. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 6, characterized in that: The improved Canny edge detection algorithm uses bilateral filter instead of Gaussian filter and adds gradient direction calculation.

8. The method for high-precision measurement of bridge piers based on a flying displacement measurement robot according to claim 1, characterized in that: The ground measurement auxiliary equipment includes a total station and a laser receiver. A prism and a laser rangefinder are set on the measuring rod. The total station is used to cooperate with the prism on the measuring rod, and the laser receiver is used to cooperate with the laser rangefinder on the measuring rod.

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