A bridge support displacement monitoring method and system based on color-changing photonic crystals

Abstract

The application provides a bridge support displacement monitoring method and system based on a color-changing photonic crystal, and belongs to the technical field of bridge structure health monitoring, and aims to solve the problems of difficult installation and maintenance, high equipment cost, complex data processing, great environmental interference or low efficiency of the existing bridge support displacement monitoring technology. The application utilizes the characteristic that the color-changing photonic crystal sensor generates visible spectrum change when stretched, and directly installs the sensor between the bridge support and the beam body, so that the sensor does not need external power supply and completely relies on mechanical stretching to drive color change, thereby completely solving the problems of complex installation and difficult maintenance caused by the need of laying power supply lines and signal cables for the traditional contact sensor.

Description

Technical Field

[0001] This invention relates to the field of bridge structural health monitoring technology, and in particular to a bridge support displacement monitoring method and system based on color-changing photonic crystals. Background Technology

[0002] Bridge bearings, as key force-transmitting components connecting the superstructure and substructure of a bridge, primarily function to effectively transfer the reaction forces from the superstructure to the substructure and to accommodate horizontal displacement and rotation of the bridge beam caused by temperature changes, shrinkage, creep, and load effects. Bridge bearing displacement (including longitudinal slippage and lateral displacement) is a crucial indicator for assessing the stress state, operational safety, and durability of a bridge structure. Excessive displacement of bridge bearings can lead to increased additional stress on the structure, potentially causing catastrophic accidents such as beam collapse. Therefore, in accordance with relevant requirements such as the "Technical Specification for Monitoring Highway Bridge Structures" (JT / T 1037-2022), long-term, accurate, and stable monitoring of bridge bearing displacement is of great significance for ensuring the safe operation of bridge structures throughout their entire life cycle.

[0003] Currently, monitoring technologies for bridge bearing displacement both domestically and internationally are mainly divided into three categories: contact sensor measurement, non-contact remote monitoring, and manual inspection.

[0004] Contact sensor measurement is a traditional method for automated monitoring, mainly achieved by deploying drawstring, laser, or ultrasonic displacement sensors at relevant locations on bridge bearings, piers, or beams. While these methods can directly acquire displacement data, they typically require installing the sensor body on the piers or beams, laying power supply lines and signal transmission cables, making the installation process complex and maintenance difficult. Especially in hard-to-reach locations such as bridge bearings on large bridges, sensor installation and subsequent wiring maintenance costs are high, and the sensors are prone to failure due to long-term exposure to complex environments.

[0005] Non-contact remote monitoring technologies aim to overcome the wiring challenges of contact-based measurements and mainly include microwave vibration measurement, image recognition, and 3D laser scanning. Microwave vibration measurement measures displacement by emitting microwaves and analyzing the echo signals, but its equipment is expensive and has certain requirements regarding the reflectivity of the target object. Image recognition technology uses high-definition cameras to capture images of the bridge support area and uses algorithms to identify changes in the pixel coordinates of feature points to calculate displacement. While this method achieves non-contact measurement, it is susceptible to interference from factors such as changes in lighting, rain, fog, and lens damage. Furthermore, the accuracy of measuring minute displacements relies on complex filtering algorithms and multi-frame data fusion processing, making data processing difficult and easily affecting measurement accuracy. 3D laser scanning, on the other hand, suffers from limitations such as expensive equipment, large data processing volumes, and difficulty in achieving high-frequency continuous monitoring.

[0006] Manual and semi-automatic inspections, as the most traditional methods, typically involve inspectors carrying equipment such as levels and total stations to the site for measurement. This method is not only inefficient but also highly susceptible to human error, making it difficult to guarantee the long-term stability and continuity of measurement results. Especially for large bridges, manual inspections cannot cover all monitoring points and pose safety risks associated with working at heights.

[0007] In summary, existing bridge bearing displacement monitoring technologies generally suffer from problems such as difficult installation and maintenance, high equipment costs, complex data processing, and high susceptibility to environmental interference or low efficiency. They cannot simultaneously meet the monitoring requirements of high precision, low cost, easy deployment, and long-term stability, and there is room for improvement. Summary of the Invention

[0008] This invention provides a bridge bearing displacement monitoring method and system based on color-changing photonic crystals, which solves the problems of existing bridge bearing displacement monitoring technologies, such as difficult installation and maintenance, high equipment costs, complex data processing, and high susceptibility to environmental interference or low efficiency.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] In a first aspect, a method for monitoring bridge support displacement based on a color-changing photonic crystal is provided, the method comprising:

[0011] S1. A color-changing photonic crystal sensor is installed between the bridge bearing and the beam. The color-changing photonic crystal sensor includes a longitudinal sensor arranged along the longitudinal direction of the bridge bearing and a transverse sensor arranged along the transverse direction of the bridge bearing. The two ends of the longitudinal sensor and the transverse sensor are respectively fixed to the side of the bridge bearing and the bottom of the beam, so that the relative displacement between the bridge bearing and the beam is converted into the tensile deformation and color feature change of the color-changing photonic crystal sensor.

[0012] S2. Configure a drone inspection system and control the inspection drone to fly to the bridge support monitoring area according to a preset route. The drone inspection system includes a drone base station, the inspection drone, and a high-definition camera and lighting equipment mounted on the inspection drone.

[0013] S3. Acquire a high-resolution image of the color-changing photonic crystal sensor using the high-definition camera with the assistance of the lighting equipment, and send the high-resolution image to the image processing system;

[0014] S4. The high-resolution image is preprocessed and sensor region is identified by the image processing system to extract the color features and contour information of the color-changing photonic crystal sensor.

[0015] S5. Based on the pre-established mapping relationship between the stretching length and color features of the color-changing photonic crystal sensor, the stretching lengths of the longitudinal sensor and the transverse sensor in the current state are obtained by inverting the color features.

[0016] S6. Based on the tensile lengths of the longitudinal and transverse sensors in the current state and the geometric parameters of the sensors during initial installation, the bridge bearing displacement is calculated. The bridge bearing displacement includes the longitudinal slippage and the transverse displacement of the bridge bearing.

[0017] Optionally, the color-changing photonic crystal sensor includes:

[0018] An elastic substrate is used to impart stretchability to the color-changing photonic crystal sensor;

[0019] A colloidal crystal film, embedded in the elastic substrate and assembled from periodically arranged nanoparticles, is used to generate structural color changes under tensile deformation.

[0020] A clamping device is disposed at both ends of the color-changing photonic crystal sensor for fixing the color-changing photonic crystal sensor between the bridge support and the beam.

[0021] The colloidal crystal film undergoes in-plane lattice period changes under mechanical stress, causing a shift in the structural color wavelength. The structural color wavelength and the lattice period of the colloidal crystal film satisfy the Bragg diffraction relationship.

[0022] Optionally, the color-changing photonic crystal sensor is a passive sensor, and the color feature change is directly driven by the mechanical tension caused by the relative displacement between the bridge support and the beam. The color-changing photonic crystal sensor does not require an external power supply.

[0023] The color-changing photonic crystal sensor is provided with a transparent protective layer on the outside. The transparent protective layer is made of a polymer material with high light transmittance and is used to isolate external moisture, dust and ultraviolet radiation.

[0024] Optionally, the pre-established mapping relationship between the stretched length and color features of the color-changing photonic crystal sensor is established in the following manner:

[0025] Multiple preset stretch lengths are applied to the color-changing photonic crystal sensor under a calibration environment;

[0026] The calibration images of the color-changing photonic crystal sensor at each preset stretching length were acquired respectively;

[0027] Extract color features corresponding to each preset stretch length from the calibration image;

[0028] Based on each preset stretching length and the corresponding color feature, a fitting function relationship between the stretching length and the color feature is established, and the fitting function relationship is stored in the image processing system.

[0029] Optionally, a color-changing photonic crystal sensor is installed between the bridge bearing and the beam, including:

[0030] One end of the longitudinal sensor and one end of the transverse sensor are fixed to a fixed point on the side of the bridge bearing using a common clamping device, and the fixed point on the side of the bridge bearing is used as a reference point for displacement monitoring.

[0031] The other end of the longitudinal sensor is fixed to the first fixed point on the bottom surface of the beam.

[0032] The other end of the transverse sensor is fixed to the second fixing point on the bottom surface of the beam.

[0033] The bridge bearing side fixing point, the first fixing point on the bottom surface of the beam, and the second fixing point on the bottom surface of the beam are used to form a geometric constraint relationship for calculating the longitudinal slip and the lateral displacement of the bridge bearing.

[0034] Optionally, the inspection drone is controlled to fly along a preset route to the bridge support monitoring area, including:

[0035] The drone base station performs take-off and landing control, charging control, and data transmission control on the inspection drone.

[0036] The inspection drone is controlled to fly to multiple bridge support monitoring points along a preset three-dimensional route.

[0037] The inspection drone uses autonomous navigation and obstacle avoidance functions to hover at the shooting position corresponding to the current bridge support monitoring point.

[0038] Acquiring high-resolution images from the color-changing photonic crystal sensor includes:

[0039] The high-resolution images are captured using a high-definition camera with a resolution of at least 20 megapixels;

[0040] The color-changing photonic crystal sensor is illuminated by an LED ring light;

[0041] The color-changing photonic crystal sensor area in the high-resolution image is located using an image recognition algorithm, and the inspection drone is controlled to adjust its hovering position so that the color-changing photonic crystal sensor area is located at a preset position in the captured image.

[0042] Optionally, the high-resolution image is preprocessed and sensor region identified by the image processing system to extract the color features and contour information of the color-changing photonic crystal sensor, including:

[0043] The high-resolution image is subjected to denoising, image enhancement, and color correction.

[0044] Sensor region segmentation is performed on the preprocessed high-resolution image to determine the color-changing photonic crystal sensor region;

[0045] At least one of the RGB color values, hue values, saturation values, brightness values, and structural color wavelength parameters of the color-changing photonic crystal sensor region is extracted as the color feature;

[0046] The geometric contour of the color-changing photonic crystal sensor region is extracted as the contour information;

[0047] After extracting the contour information of the color-changing photonic crystal sensor, the method further includes:

[0048] Based on the contour information, determine whether the color-changing photonic crystal sensor is twisted, partially detached, or obstructed by foreign objects;

[0049] If the contour information indicates that the color-changing photonic crystal sensor is twisted, partially detached, or obstructed by foreign objects, the corresponding monitoring data will be marked as suspicious data, and a manual review prompt will be output.

[0050] Optionally, the method for calculating the bridge support displacement is as follows:

[0051] The lateral displacement Δx and longitudinal slippage Δy of the bridge bearing are calculated according to Equations (1) and (2), respectively:

[0052] (1)

[0053] (2)

[0054] Wherein, β and δ are calculated according to equations (3) and (4), respectively:

[0055] (3)

[0056] (4)

[0057] In the formula, Δx is the lateral displacement distance of the bridge bearing, and Δy is the longitudinal sliding distance of the bridge bearing; a is the horizontal lateral distance between fixed points A and B on the bottom surface of the beam, b is the horizontal longitudinal distance between fixed points A and B on the bottom surface of the beam, L is the straight-line distance between fixed points A and B on the bottom surface of the beam, and h is the vertical distance between the side fixed point O of the bridge bearing and the plane of fixed points A and B on the bottom surface of the beam; l1 and l2 are the initial lengths of the longitudinal sensor OA and the initial length of the lateral sensor OB during installation, respectively; l3 and l4 are the lengths of the longitudinal sensor OA' and the lateral sensor OB' after displacement, respectively.

[0058] Secondly, a bridge bearing displacement monitoring system is provided, the system comprising:

[0059] A color-changing photonic crystal sensor is used to be installed between bridge bearings and beams, and generates tensile deformation and color feature changes when the bridge bearings and beams are relatively displaced.

[0060] The drone inspection system is used to fly to the bridge support monitoring area according to a preset route, collect high-resolution images from the color-changing photonic crystal sensor, and send the high-resolution images to the image processing system.

[0061] An image processing system is used to preprocess the high-resolution image and identify the sensor region, extract the color features and contour information of the color-changing photonic crystal sensor, invert the tensile length of the color-changing photonic crystal sensor based on the color features, and calculate the bridge support displacement based on the tensile length and the geometric parameters of the sensor at the time of initial installation.

[0062] The image processing system includes an image preprocessing module, a sensor positioning module, a color feature extraction module, a stretching length inversion module, a displacement calculation module, and an anomaly marking module.

[0063] Optionally, the color-changing photonic crystal sensor includes a longitudinal sensor and a transverse sensor;

[0064] The longitudinal sensor is arranged along the longitudinal direction of the bridge bearing and is used to detect the longitudinal slippage of the bridge bearing.

[0065] The lateral sensor is arranged laterally along the bridge support to detect the lateral displacement of the bridge support.

[0066] One end of the longitudinal sensor and the transverse sensor are fixed to the side of the bridge support, and the other end is fixed to the bottom surface of the beam.

[0067] The drone inspection system includes:

[0068] The drone base station is used to control the take-off and landing, charging, and data transmission of inspection drones.

[0069] Inspection drones are used to fly to the bridge bearing monitoring area according to a preset route and hover at the shooting position corresponding to the bridge bearing monitoring point;

[0070] A high-definition camera, mounted on the inspection drone, is used to acquire high-resolution images from the color-changing photonic crystal sensor;

[0071] Lighting equipment, mounted on the inspection drone, is used to provide supplemental lighting for the color-changing photonic crystal sensor when acquiring the high-resolution image.

[0072] The image preprocessing module is used to perform noise reduction, image enhancement, and color correction on the high-resolution image.

[0073] The sensor positioning module is used to identify and locate the color-changing photonic crystal sensor region from the preprocessed high-resolution image;

[0074] The color feature extraction module is used to extract at least one of RGB color values, hue values, saturation values, brightness values, and structural color wavelength parameters from the color-changing photonic crystal sensor region.

[0075] The stretching length inversion module is used to invert the current stretching length of the color-changing photonic crystal sensor based on the color features and the pre-established mapping relationship between stretching length and color features.

[0076] The displacement calculation module is used to calculate the displacement of the bridge support based on the current tensile length and the geometric parameters of the sensor at the time of initial installation;

[0077] The anomaly marking module is used to determine whether the color-changing photonic crystal sensor is twisted, partially detached, or obstructed by foreign objects based on the contour information, and to mark the corresponding monitoring data as suspicious data when an anomaly is found.

[0078] Thirdly, an electronic device is provided, comprising: a processor and a memory; the memory is used to store a computer program, which, when executed by the processor, causes the electronic device to perform the bridge support displacement monitoring method and system based on color-changing photonic crystals as described in the first aspect.

[0079] In one possible design, the electronic device described in the third aspect may further include a transceiver. This transceiver may be a transceiver circuit or an interface circuit. The transceiver can be used for communication between the electronic device described in the third aspect and other electronic devices.

[0080] In the embodiments of the present invention, the electronic device described in the third aspect may be a terminal, or a chip (system) or other component or assembly disposed in the terminal, or a system containing the terminal.

[0081] Fourthly, a computer-readable storage medium is provided, comprising: a computer program or instructions; when the computer program or instructions are executed on a computer, the computer causes the computer to perform the bridge support displacement monitoring method and system based on color-changing photonic crystals described in the first aspect.

[0082] In summary, the above methods and systems have the following technical effects:

[0083] 1. This invention utilizes the characteristic of color-changing photonic crystal sensors to produce visible spectrum changes when stretched. It can be directly installed between bridge supports and beams. The sensor does not require external power supply and relies on mechanical stretching to drive color changes, thus solving the problems of complex installation and difficult maintenance caused by the need to lay power supply lines and signal cables for traditional contact sensors.

[0084] 2. This invention uses drones equipped with high-definition cameras for regular inspections, enabling automated acquisition of sensor images without requiring personnel to reach the bridge bearing area. This significantly reduces the labor intensity and safety risks of manual inspections, while also enabling high-frequency, full-coverage monitoring of multiple bridge bearings on large bridges.

[0085] 3. This invention establishes a mapping relationship between the sensor's tensile length and color features, inverts to obtain accurate bridge support displacement, and further provides a displacement calculation formula based on a geometric model, realizing quantitative and high-precision measurement of bridge support displacement, overcoming the shortcomings of traditional image recognition technology that rely on pixel coordinate changes and are easily affected by light and angle interference.

[0086] 4. The color characteristics of the color-changing photonic crystal sensor in this invention have a clear physical correspondence with the stretching length, namely the Bragg diffraction law. It has good environmental adaptability, and when used with lighting equipment during UAV inspections, it can effectively eliminate the influence of natural light changes, ensuring the stability and repeatability of monitoring results under different weather conditions and time periods.

[0087] 5. The present invention has a simple structure and low cost. The sensor itself is passive, lightweight, easy to install and replace. The UAV inspection system can simultaneously monitor other parts of the existing infrastructure. The overall solution is easy to promote and provides a practical and feasible technical path for long-term automated monitoring of bridge bearing displacement. Attached Figure Description

[0088] Figure 1 The flowchart shows a bridge support displacement monitoring method based on color-changing photonic crystals.

[0089] Figure 2 A schematic diagram of a bridge support displacement monitoring system that integrates a color-changing photonic crystal with a drone.

[0090] Figure 3A schematic diagram of the installation structure for a color-changing photonic crystal sensor;

[0091] Figure 4 A schematic diagram illustrating the working principle of a color-changing photonic crystal sensor;

[0092] Figure 5 A schematic diagram of drone inspection and image acquisition;

[0093] Figure 6 A schematic diagram of the geometric model for calculating the displacement of bridge supports.

[0094] In the diagram: 11. Pier; 12. Bridge bearing; 13. Beam; 14. Longitudinal sensor; 15. Lateral sensor; 2. Color-changing photonic crystal sensor; 21. Elastic substrate; 22. Colloidal crystal film; 23. Shared clamping device; 24. First clamping device; 25. Second clamping device; 26. Transparent protective layer; 31. UAV base station; 32. Inspection UAV; 33. High-definition camera; 34. LED ring light; 35. Image processing system; 41. Incident white light; 42. Visible light violet end; 43. Visible light red end; 44. Visible light spectrum. Detailed Implementation

[0095] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0096] In the description of the embodiments of the present invention, unless otherwise stated, " / " indicates that the objects before and after are in an "or" relationship. For example, A / B can represent A or B. "And / or" in the embodiments of the present invention is merely a description of the relationship between the related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone, where A and B can be singular or plural. Furthermore, in the description of the embodiments of the present invention, unless otherwise stated, "multiple" refers to two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple. Additionally, to facilitate a clear description of the technical solutions of the embodiments of the present invention, the terms "first" and "second" are used in the embodiments of the present invention to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or order of execution, and that "first," "second," etc., are not necessarily different. Furthermore, in the embodiments of this invention, words such as "exemplary" or "for example" are used to indicate that something is being described as an example, illustration, or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of this invention should not be construed as being more preferred or advantageous than other embodiments or design schemes. Specifically, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner for ease of understanding.

[0097] The network architecture and business scenarios described in the embodiments of this invention are for the purpose of more clearly illustrating the technical solutions of the embodiments of this invention, and do not constitute a limitation on the technical solutions provided by the embodiments of this invention. As those skilled in the art will know, with the evolution of network architecture and the emergence of new business scenarios, the technical solutions provided by the embodiments of this invention are also applicable to similar technical problems.

[0098] Figure 1 This is a flowchart illustrating the method provided in an embodiment of the present invention. The specific process is as follows: A bridge bearing displacement monitoring method is applied to a bridge bearing 12 displacement monitoring system. The system includes a color-changing photonic crystal sensor 2, a drone inspection system, and an image processing system 35, which form the bridge bearing 12 displacement monitoring architecture. The drone inspection system includes a drone base station 31, an inspection drone 32, and a high-definition camera 33 and lighting equipment mounted on the inspection drone 32. The image processing system 35 includes an image preprocessing module, a sensor positioning module, a color feature extraction module, a stretching length inversion module, a displacement calculation module, and an anomaly marking module. The method includes:

[0099] S1. A color-changing photonic crystal sensor 2 is installed between the bridge support 12 and the beam 13. The color-changing photonic crystal sensor 2 includes a longitudinal sensor 14 arranged along the longitudinal direction of the bridge support 12 and a transverse sensor 15 arranged along the transverse direction of the bridge support 12. The two ends of the longitudinal sensor 14 and the transverse sensor 15 are respectively fixed to the side of the bridge support 12 and the bottom surface of the beam 13, so that the relative displacement between the bridge support 12 and the beam 13 is converted into the tensile deformation and color feature change of the color-changing photonic crystal sensor 2.

[0100] Please see Figure 4 Specifically, in the figure, d represents the unstretched lattice period; d' represents the stretched lattice period; λ represents the unstretched reflected light wavelength; and λ' represents the stretched reflected light wavelength. The color-changing photonic crystal sensor 2 includes an elastic substrate 21, a colloidal crystal film 22 embedded in the elastic substrate 21, and clamping devices disposed at both ends of the sensor. The elastic substrate 21 is used to impart stretchability to the color-changing photonic crystal sensor 2. The colloidal crystal film 22 is assembled from periodically arranged nanoparticles and is used to generate structural color changes under stretching deformation. The clamping devices are used to fix the color-changing photonic crystal sensor 2 between the bridge support 12 and the beam 13.

[0101] The colloidal crystal film 22 is assembled from periodically arranged nanoparticles and can generate structural color. When relative displacement occurs between the bridge support 12 and the beam 13, the sensor is stretched, and the in-plane lattice period of the colloidal crystal film 22 changes: the unstretched lattice period d becomes the stretched lattice period d′. When incident white light 41 shines on the sensor, the wavelength of the reflected light satisfies Bragg's diffraction law: 2d sinθ = nλ. The stretched lattice period d′ is greater than the unstretched lattice period d, and the wavelength of the stretched reflected light λ′ is consequently greater than the wavelength of the unstretched reflected light λ. This manifests as a shift of structural color towards longer wavelengths, that is, a shift from the violet end 42 to the red end in the visible light spectrum. The color change is illustrated as a transition from violet to red.

[0102] Optionally, the colloidal crystal film 22 undergoes an in-plane lattice period change under mechanical stress, causing a shift in the structural color wavelength. The structural color wavelength and the lattice period of the colloidal crystal film 22 satisfy the Bragg diffraction relationship. For example, when relative displacement occurs between the bridge support 12 and the beam 13, the longitudinal sensor 14 or the transverse sensor 15 is stretched. The lattice period of the colloidal crystal film 22 increases with the stretching deformation, causing the reflected light wavelength to shift towards longer wavelengths, which manifests as a change in the structural color on the sensor surface. By identifying the wavelength parameter or RGB color value of the structural color, the displacement state of the bridge support 12 can be converted into color features that can be read by the image processing system 35.

[0103] Optionally, the color-changing photonic crystal sensor 2 is a passive sensor. The color feature change is directly driven by mechanical tension caused by the relative displacement between the bridge support 12 and the beam 13. The color-changing photonic crystal sensor 2 does not require external power supply. It is understood that the bridge support 12 is usually located below the beam 13 or on top of the pier 11, in locations that are difficult to wire and maintain. If a traditional active sensor is used, additional power supply and signal lines would be required. This embodiment utilizes mechanical tension to directly drive the color change, making the sensor body independent of on-site power supply, thereby reducing installation difficulty and subsequent maintenance costs.

[0104] Furthermore, a transparent protective layer 26 can be provided on the exterior of the color-changing photonic crystal sensor 2. This transparent protective layer 26 is made of a high-transmittance polymer material and is used to isolate external moisture, dust, and ultraviolet radiation, while allowing the inspection drone 32 to collect the color characteristics of the color-changing photonic crystal sensor 2. Thus, in the long-term service environment of the bridge, the transparent protective layer 26 can reduce the impact of rainwater, dust, ultraviolet radiation, and pollutants on the colloidal crystal film 22, enabling the sensor to maintain a stable optical response.

[0105] In terms of installation structure, one end of the longitudinal sensor 14 and the transverse sensor 15 can be fixed to a fixed point on the side of the bridge bearing 12 via a shared clamping device 23, and the fixed point on the side of the bridge bearing 12 can be used as a reference point for displacement monitoring; the other end of the longitudinal sensor 14 can be fixed to a first fixed point on the bottom surface of the beam 13; the other end of the transverse sensor 15 can be fixed to a second fixed point on the bottom surface of the beam 13; wherein, the fixed point on the side of the bridge bearing 12, the first fixed point on the bottom surface of the beam 13, and the second fixed point on the bottom surface of the beam 13 are used to form a geometric constraint relationship for calculating the longitudinal slip and the transverse displacement of the bridge bearing 12.

[0106] For example, in a bridge structure, a bridge bearing 12 is installed on the top of the pier 11, and a beam 13 is above the bridge bearing 12. A longitudinal sensor 14 is arranged along the longitudinal direction of the bridge, and a transverse sensor 15 is arranged along the transverse direction of the bridge. One end of the two sensors near the bridge bearing 12 is fixed to the same fixing point on the side of the bridge bearing 12, and the other end is fixed to the first fixing point and the second fixing point on the bottom surface of the beam 13, respectively. When the beam 13 slides longitudinally or moves laterally relative to the bridge bearing 12, the lengths of the two sensors change differently. The image processing system 35 can then decouple the current lengths and initial geometric parameters of the two sensors to obtain the displacement of the bridge bearing 12.

[0107] S2. Configure a drone inspection system and control the inspection drone 32 to fly to the monitoring area of ​​the bridge support 12 according to the preset route. The drone inspection system includes a drone base station 31, the inspection drone 32, and a high-definition camera 33 and lighting equipment mounted on the inspection drone 32.

[0108] Specifically, the drone base station 31 is used to perform take-off and landing control, charging control, and data transmission control for the inspection drone 32; the inspection drone 32 is used to fly to the monitoring area of ​​the bridge support 12 according to the preset route and hover at the shooting position corresponding to the monitoring point of the bridge support 12; the high-definition camera 33 is mounted on the inspection drone 32 and is used to collect high-resolution images of the color-changing photonic crystal sensor 2; the lighting equipment is mounted on the inspection drone 32 and is used to provide supplementary lighting for the color-changing photonic crystal sensor 2 when collecting the high-resolution images.

[0109] Optionally, controlling the inspection drone 32 to fly to the monitoring area of ​​the bridge support 12 according to a preset route includes: performing take-off and landing control, charging control and data transmission control on the inspection drone 32 through the drone base station 31; controlling the inspection drone 32 to fly to multiple bridge support 12 monitoring points according to a preset three-dimensional route; and using the autonomous navigation and obstacle avoidance functions of the inspection drone 32 to make the inspection drone 32 hover at the shooting position corresponding to the current bridge support 12 monitoring point.

[0110] Understandably, large bridges typically have multiple bridge bearing monitoring points (12), and some of these bearing areas are located at high altitudes, in narrow spaces, or in locations difficult for personnel to access. If manual inspection is used, inspectors would need to carry measuring equipment into the vicinity of the bridge bearings (12), which is inefficient and poses operational risks. This embodiment uses a drone base station (31) and an inspection drone (32) to form a mobile data acquisition terminal, enabling the inspection drone (32) to automatically reach each bridge bearing (12) monitoring point according to a preset three-dimensional flight path and complete non-contact image acquisition.

[0111] For example, the preset three-dimensional flight path can be set according to the bridge bearing 12 number, the pier 11 position, the beam bottom clearance and surrounding obstacles. After taking off from the drone base station 31, the inspection drone 32 flies to each bridge bearing 12 monitoring point in sequence and hovers at the best shooting position at each bridge bearing 12 monitoring point. After completing the image acquisition, the inspection drone 32 can automatically fly to the next bridge bearing 12 monitoring point or return to the drone base station 31 to perform charging and data synchronization.

[0112] S3. The high-resolution image of the color-changing photonic crystal sensor 2 is acquired by the high-definition camera 33 with the assistance of the lighting equipment, and the high-resolution image is sent to the image processing system 35.

[0113] Specifically, acquiring high-resolution images of the color-changing photonic crystal sensor 2 may include: acquiring the high-resolution images using a high-definition camera 33 with a resolution of not less than 20 million pixels; providing supplemental lighting to the color-changing photonic crystal sensor 2 using an LED ring light 34; locating the area of ​​the color-changing photonic crystal sensor 2 in the high-resolution image using an image recognition algorithm; and controlling the inspection drone 32 to adjust its hovering position so that the area of ​​the color-changing photonic crystal sensor 2 is located at a preset position in the acquired image.

[0114] Understandably, the color characteristics of the color-changing photonic crystal sensor 2 are used to invert the tensile length, therefore the image acquisition quality directly affects the accuracy of displacement calculation. At the bridge site, there may be interference such as insufficient natural light, backlighting, shadows, rain, fog, dust on the beam bottom, and changes in shooting angle. Direct image acquisition can easily cause color feature drift. Therefore, this embodiment uses a high-definition camera 33 and an LED ring light 34 to acquire images, ensuring that the sensor area obtains clear, uniform, and comparable image data.

[0115] For example, the LED ring light 34 can be arranged around the lens of the high-definition camera 33 to provide coaxial or near-coaxial auxiliary lighting to the sensor area when the inspection drone 32 hovers and shoots, so as to reduce shadows and reflections; the image recognition algorithm can identify the color-changing photonic crystal sensor 2 area in the picture. When the sensor area is off the center of the picture or the size does not meet the preset acquisition conditions, the inspection drone 32 finely adjusts the hovering position or shooting distance and continuously acquires multiple high-resolution images for subsequent image processing system 35 to screen and process.

[0116] Furthermore, the high-resolution images can be transmitted to the image processing system 35 in real time via a wireless communication link, or they can be cached in the inspection drone 32 or drone base station 31 and then uploaded to the image processing system 35 in batches after the inspection task is completed. Thus, the system can adapt to different bridge inspection scenarios, both with good and limited on-site communication conditions.

[0117] S4. The high-resolution image is preprocessed and sensor region is identified by the image processing system 35 to extract the color features and contour information of the color-changing photonic crystal sensor 2.

[0118] Optionally, the image processing system 35 preprocesses the high-resolution image and performs sensor region identification to extract the color features and contour information of the color-changing photonic crystal sensor 2, including: performing noise reduction, image enhancement, and color correction on the high-resolution image; performing sensor region segmentation on the preprocessed high-resolution image to determine the region of the color-changing photonic crystal sensor 2; extracting at least one of the RGB color values, hue values, saturation values, brightness values, and structural color wavelength parameters of the region of the color-changing photonic crystal sensor 2 as the color features; and extracting the geometric contour of the region of the color-changing photonic crystal sensor 2 as the contour information.

[0119] Specifically, the image preprocessing module can perform denoising, image enhancement, and color correction on high-resolution images. Denoising is used to reduce random noise generated during image acquisition and wireless transmission; image enhancement is used to improve the contrast between the sensor area and the bridge background; and color correction is used to reduce color deviations caused by different shooting times, different lighting intensities, and different shooting angles.

[0120] The sensor localization module can identify and locate the region of the color-changing photonic crystal sensor 2 from the pre-processed high-resolution image. For example, the sensor localization module can use an image segmentation-based localization algorithm or a trained target detection model to automatically identify the positions of the longitudinal sensor 14 and the transverse sensor 15, and filter out non-target areas such as bridge support 12, beam bottom, bolts, dust, and background textures.

[0121] The color feature extraction module can extract at least one of the following from the color-changing photonic crystal sensor 2 region: RGB color value, hue value, saturation value, lightness value, and structural color wavelength parameter. For example, the system can average the RGB channel values ​​of all pixels within the effective area of ​​the sensor, or it can calculate color features after excluding bright reflective areas, shadow areas, and blurred edge areas, to improve the stability of the correspondence between color features and the sensor's stretched state.

[0122] Optionally, after extracting the contour information of the color-changing photonic crystal sensor 2, the method further includes: determining whether the color-changing photonic crystal sensor 2 is twisted, partially detached, or obstructed by foreign objects based on the contour information; if the contour information indicates that the color-changing photonic crystal sensor 2 is twisted, partially detached, or obstructed by foreign objects, then the corresponding monitoring data is marked as suspicious data, and a manual review prompt is output.

[0123] For example, when the sensor profile is significantly bent, partially missing, or obscured by mud and sand, even if the color features can still be extracted, the inverted stretching length may be unreliable. The anomaly marking module can determine whether the monitoring data is reliable based on the profile integrity, length-to-width ratio, boundary continuity, and obscured area, and mark the data as suspicious data in abnormal situations to prevent abnormal images from directly entering the displacement calculation process of bridge bearing 12.

[0124] S5. Based on the pre-established mapping relationship between the stretching length and color features of the color-changing photonic crystal sensor 2, the stretching lengths of the longitudinal sensor 14 and the transverse sensor 15 in the current state are obtained by inverting the color features.

[0125] Specifically, the pre-established mapping relationship between the stretching length and color features of the color-changing photonic crystal sensor 2 can be established as follows: multiple preset stretching lengths are applied to the color-changing photonic crystal sensor 2 under a calibration environment; calibration images of the color-changing photonic crystal sensor 2 at each preset stretching length are acquired respectively; color features corresponding to each preset stretching length are extracted from the calibration images; a fitting function relationship between the stretching length and the color features is established based on each preset stretching length and the corresponding color features, and the fitting function relationship is stored in the image processing system 35.

[0126] For example, during the laboratory calibration phase, a precision displacement stage can be used to apply multiple known stretching lengths to the color-changing photonic crystal sensor 2, for example, starting from an unstretched state and gradually stretching it according to a preset step size. At the same time, a high-definition camera 33 or a spectrometer is used to record the color features corresponding to each stretching length. The image processing system 35 establishes a fitting function relationship between the stretching length and the RGB color value, hue value or structural color wavelength parameter based on multiple calibration samples, and stores the fitting function relationship in the calibration mapping storage module.

[0127] During the on-site monitoring phase, the stretching length inversion module reads the current color features output by the color feature extraction module and calls the fitting function relationship in the calibration mapping storage module. It then obtains the stretching lengths of the longitudinal sensor 14 and the transverse sensor 15 in the current state through interpolation, fitting function solving, or table lookup. Therefore, the system no longer directly relies on the pixel displacement of surface feature points of the bridge bearing 12 in the image, but instead indirectly inverts the sensor stretching length through the color encoding of the passive color-changing photonic crystal sensor 2, reducing the impact of shooting distance and changes in the background texture of the bridge bearing 12 on displacement recognition.

[0128] It is understandable that there may be differences in temperature, humidity, and lighting conditions at the same bridge site. To improve the adaptability of the mapping relationship, calibration images can be acquired under different supplementary lighting intensities, different shooting angles, or different environmental conditions. The image processing system 35 can also introduce color correction parameters into the color features to ensure that the color features extracted on site are consistent with the color features in the calibration stage.

[0129] S6. Based on the tensile lengths of the longitudinal sensor 14 and the transverse sensor 15 in the current state and the geometric parameters of the sensors during initial installation, the displacement of the bridge support 12 is calculated. The displacement of the bridge support 12 includes the longitudinal slippage of the bridge support 12 and the transverse displacement of the bridge support 12.

[0130] Optionally, the displacement of the bridge bearing 12 is calculated based on the tensile lengths of the longitudinal sensor 14 and the transverse sensor 15 in the current state and the geometric parameters of the sensors during initial installation. This includes: obtaining the initial length of the longitudinal sensor 14, the initial length of the transverse sensor 15, the current length of the longitudinal sensor 14, and the current length of the transverse sensor 15; obtaining the initial geometric parameters between the side fixing point of the bridge bearing 12, the first fixing point on the bottom surface of the beam 13, and the second fixing point on the bottom surface of the beam 13; and calculating the longitudinal slip and transverse displacement of the bridge bearing 12 based on geometric constraints using the initial geometric parameters, the initial length of the longitudinal sensor 14, the initial length of the transverse sensor 15, the current length of the longitudinal sensor 14, and the current length of the transverse sensor 15.

[0131] Please see Figure 2 , Figure 3 and Figure 6 Specifically, among them, Figure 6In the diagram, O represents the side fixing point of the bridge bearing; A represents the first fixing point on the bottom surface of the beam; B represents the second fixing point on the bottom surface of the beam; A' represents the first fixing point on the bottom surface of the beam after displacement; B' represents the second fixing point on the bottom surface of the beam after displacement; l1 represents the initial length of the longitudinal sensor OA; l2 represents the initial length of the transverse sensor OB; l3 represents the length of the longitudinal sensor OA' after displacement; l4 represents the length of the transverse sensor OB' after displacement; a represents the horizontal transverse distance between fixing points A and B on the bottom surface of the beam; b represents the horizontal longitudinal distance between fixing points A and B on the bottom surface of the beam; L represents the straight-line distance between fixing points A and B on the bottom surface of the beam; and h represents the vertical distance between the side fixing point O of the bridge bearing and the plane containing fixing points A and B on the bottom surface of the beam. The geometric parameters of the sensors during initial installation may include the vertical distance between the plane containing the side fixing point of the bridge bearing 12 and the bottom fixing point of the beam 13, the transverse distance, longitudinal distance, or straight-line distance between the first fixing point and the second fixing point on the bottom surface of the beam 13, and the lengths of the longitudinal sensor 14 and the transverse sensor 15 in the initial installation state. After the image processing system 35 obtains the current lengths of the longitudinal sensor 14 and the transverse sensor 15 through inversion, it can establish the geometric constraint relationship between the fixed point on the side of the bridge support 12 and the fixed point on the bottom surface of the beam 13 by combining the above geometric parameters.

[0132] For example, the side fixing point of the bridge bearing 12 can be recorded as the reference point, and the first fixing point and the second fixing point on the bottom surface of the beam 13 can be used as the fixing ends of the longitudinal sensor 14 and the transverse sensor 15, respectively. When the bridge bearing 12 experiences longitudinal slippage, the tensile length of the longitudinal sensor 14 changes significantly. When the bridge bearing 12 experiences transverse displacement, the tensile length of the transverse sensor 15 changes significantly. When the bridge bearing 12 experiences both longitudinal slippage and transverse displacement, the current lengths of the two sensors participate in the geometric solution to obtain the longitudinal slippage and transverse displacement of the bridge bearing 12.

[0133] In one embodiment, the image processing system 35 can read the initial lengths of the longitudinal sensor 14 and the transverse sensor 15 from the database, and inversely obtain the current lengths of the longitudinal sensor 14 and the transverse sensor 15 based on color features. Subsequently, the displacement calculation module calls the initial geometric parameters between the side fixing point of the bridge support 12, the first fixing point on the bottom surface of the beam 13, and the second fixing point on the bottom surface of the beam 13, and calculates the transverse displacement distance and the longitudinal sliding distance of the bridge support 12 according to a preset geometric calculation model. Thus, the color changes of the two sensors can be converted into quantifiable displacement results of the bridge support 12.

[0134] Through the above steps, this embodiment converts the relative displacement between the bridge bearing 12 and the beam 13 into a structural color change of the color-changing photonic crystal sensor 2. Then, the sensor image is collected by the UAV inspection system, and the image processing system 35 performs color feature extraction, stretching length inversion and geometric displacement calculation. This realizes passive, remote and automated monitoring of the displacement of the bridge bearing 12, avoids the problem of on-site power supply and wiring required by traditional contact sensors, and also reduces the error of manual inspection and traditional image feature point recognition methods in complex bridge environments.

[0135] In one embodiment, the relevant parameters are known as follows: a=30cm, b=30cm, h=20cm, l1=40cm, l2=42cm.

[0136] During the first monitoring, l3 = 44 cm and l4 = 46 cm. Substituting these values ​​into the above calculation formula, we obtain the following results: the lateral displacement distance of bridge bearing 12 is −3.98 cm, and the longitudinal slip distance Δy of bridge bearing 12 is 3.72 cm.

[0137] During the second monitoring, l3 = 45 cm and l4 = 45 cm. Substituting these values ​​into the above calculation formula, we obtain the following results: the lateral displacement distance of bridge bearing 12 is −2.52 cm, and the longitudinal slip distance Δy of bridge bearing 12 is 5.25 cm.

[0138] The following details a bridge bearing displacement monitoring system for performing the methods provided in embodiments of the present invention. The system is configured to include:

[0139] The color-changing photonic crystal sensor 2 is used to be installed between the bridge support 12 and the beam 13, and generates tensile deformation and color feature change when the bridge support 12 and the beam 13 are relatively displaced.

[0140] The drone inspection system is used to fly to the monitoring area of ​​the bridge support 12 according to a preset route, collect high-resolution images of the color-changing photonic crystal sensor 2, and send the high-resolution images to the image processing system 35;

[0141] The image processing system 35 is used to preprocess the high-resolution image and identify the sensor region, extract the color features and contour information of the color-changing photonic crystal sensor 2, invert the stretching length of the color-changing photonic crystal sensor 2 based on the color features, and calculate the displacement of the bridge support 12 according to the stretching length and the geometric parameters of the sensor at the time of initial installation.

[0142] The color-changing photonic crystal sensor 2 includes a longitudinal sensor 14 and a transverse sensor 15. The longitudinal sensor 14 is arranged longitudinally along the bridge support 12 and is used to sense the longitudinal slippage of the bridge support 12. The transverse sensor 15 is arranged transversely along the bridge support 12 and is used to sense the transverse displacement of the bridge support 12. One end of the longitudinal sensor 14 and the transverse sensor 15 are fixed to the side of the bridge support 12, and the other end is fixed to the bottom surface of the beam 13.

[0143] Please see Figures 5-6 The drone inspection system includes a drone base station 31, an inspection drone 32, a high-definition camera 33, and lighting equipment. The drone base station 31 controls the take-off and landing, charging, and data transmission of the inspection drone 32. The inspection drone 32 flies along a preset route to the monitoring area of ​​the bridge support 12 and hovers at the shooting position corresponding to the monitoring point of the bridge support 12. The high-definition camera 33 is mounted on the inspection drone 32 and is used to acquire high-resolution images of the color-changing photonic crystal sensor 2. The lighting equipment is mounted on the inspection drone 32 and is used to provide supplementary lighting for the color-changing photonic crystal sensor 2 when acquiring the high-resolution images.

[0144] The image processing system 35 includes an image preprocessing module, a sensor positioning module, a color feature extraction module, a stretching length inversion module, a displacement calculation module, an anomaly marking module, and a calibration mapping storage module.

[0145] The image preprocessing module is used to perform denoising, image enhancement, and color correction on the high-resolution image; the sensor positioning module is used to identify and locate the region of the color-changing photonic crystal sensor 2 from the preprocessed high-resolution image; the color feature extraction module is used to extract at least one of RGB color values, hue values, saturation values, brightness values, and structural color wavelength parameters from the region of the color-changing photonic crystal sensor 2; the stretching length inversion module is used to invert the current stretching length of the color-changing photonic crystal sensor 2 based on the color features and the pre-established mapping relationship between stretching length and color features; the displacement calculation module is used to calculate the displacement of the bridge support 12 based on the current stretching length and the geometric parameters at the initial installation of the sensor; the anomaly marking module is used to determine whether the color-changing photonic crystal sensor 2 is twisted, partially detached, or obstructed by foreign objects based on the contour information, and to mark the corresponding monitoring data as suspicious data when anomalies are found; the calibration mapping storage module is used to store the fitting function relationship between the stretching length and color features of the color-changing photonic crystal sensor 2 established under the calibration environment.

[0146] Understandably, the above modules can be integrated into the same image processing terminal, or they can be distributed across the UAV base station 31, the bridge monitoring server, edge computing devices, or the cloud platform. The division of each module is mainly for illustrating the functional relationship and does not limit the specific hardware form. Through the above system modules, the aforementioned bridge bearing 12 displacement monitoring method can be realized, forming a complete closed loop for automatic bridge bearing 12 displacement monitoring, which includes passive color-changing sensing, UAV image acquisition, image preprocessing, color feature extraction, tensile length inversion, geometric displacement calculation, and abnormal data marking.

[0147] The electronic device provided in this embodiment of the invention, exemplarily, can be a network device, or a chip (system) or other component or assembly that can be disposed in a network device. The electronic device may include a processor. Optionally, the electronic device may also include a memory and / or a transceiver. The processor is coupled to the memory and transceiver, for example, by means of a communication bus connection.

[0148] In the several embodiments provided in this invention, it should be understood that the disclosed systems and methods can also be implemented in other ways. The system and method embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0149] In addition, the functional modules in the various embodiments of the present invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0150] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, an electronic device, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention.

[0151] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for monitoring bridge support displacement based on a color-changing photonic crystal, characterized in that, The method includes: S1. A color-changing photonic crystal sensor (2) is installed between the bridge bearing (12) and the beam (13). The color-changing photonic crystal sensor (2) includes a longitudinal sensor (14) arranged along the longitudinal direction of the bridge bearing (12) and a transverse sensor (15) arranged along the transverse direction of the bridge bearing (12). The two ends of the longitudinal sensor (14) and the transverse sensor (15) are respectively fixed to the side of the bridge bearing (12) and the bottom surface of the beam (13) so that the relative displacement between the bridge bearing (12) and the beam (13) is converted into the tensile deformation and color feature change of the color-changing photonic crystal sensor (2). S2. Configure a drone inspection system and control the inspection drone (32) to fly to the monitoring area of ​​the bridge support (12) according to the preset route. The drone inspection system includes a drone base station (31), the inspection drone (32), and a high-definition camera (33) and lighting equipment mounted on the inspection drone (32). S3. The high-resolution image of the color-changing photonic crystal sensor (2) is acquired by the high-definition camera (33) with the assistance of the lighting equipment, and the high-resolution image is sent to the image processing system (35). S4. The high-resolution image is preprocessed and sensor region is identified by the image processing system (35) to extract the color features and contour information of the color-changing photonic crystal sensor (2); S5. Based on the pre-established mapping relationship between the stretching length and color features of the color-changing photonic crystal sensor (2), the stretching lengths of the longitudinal sensor (14) and the transverse sensor (15) in the current state are obtained by inverting the color features. S6. Based on the tensile length of the longitudinal sensor (14) and the transverse sensor (15) under the current state and the geometric parameters of the sensor during initial installation, the displacement of the bridge bearing is calculated. The displacement of the bridge bearing includes the longitudinal slip of the bridge bearing (12) and the transverse displacement of the bridge bearing (12).

2. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, The color-changing photonic crystal sensor (2) includes: An elastic substrate (21) is used to impart stretchability to the color-changing photonic crystal sensor (2); A colloidal crystal film (22), embedded in the elastic substrate (21) and assembled from periodically arranged nanoparticles, is used to generate structural color changes under tensile deformation; A clamping device is provided at both ends of the color-changing photonic crystal sensor (2) to fix the color-changing photonic crystal sensor (2) between the bridge support (12) and the beam (13); The colloidal crystal film (22) undergoes in-plane lattice period changes under mechanical stress, causing a shift in the structural color wavelength. The structural color wavelength and the lattice period of the colloidal crystal film (22) satisfy the Bragg diffraction relationship.

3. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, The color-changing photonic crystal sensor (2) is a passive sensor. The color feature change is directly driven by the mechanical tension caused by the relative displacement between the bridge support (12) and the beam (13). The color-changing photonic crystal sensor (2) does not require external power supply. The color-changing photonic crystal sensor (2) is provided with a transparent protective layer (26) on the outside. The transparent protective layer (26) is made of a polymer material with high light transmittance and is used to isolate external water vapor, dust and ultraviolet radiation.

4. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, The pre-established mapping relationship between the stretching length and color characteristics of the color-changing photonic crystal sensor (2) is established in the following manner: Multiple preset stretch lengths are applied to the color-changing photonic crystal sensor (2) under a calibration environment; The calibration images of the color-changing photonic crystal sensor (2) at each preset stretching length were collected respectively; Extract color features corresponding to each preset stretch length from the calibration image; Based on each preset stretch length and the corresponding color feature, a fitting function relationship between the stretch length and the color feature is established, and the fitting function relationship is stored in the image processing system (35).

5. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, A color-changing photonic crystal sensor (2) is installed between the bridge bearing (12) and the beam (13), including: One end of the longitudinal sensor (14) and the transverse sensor (15) are fixed to the side fixing point of the bridge support (12) by a common clamping device (23), and the side fixing point of the bridge support (12) is used as the reference point for displacement monitoring. The other end of the longitudinal sensor (14) is fixed to the first fixed point on the bottom surface of the beam (13); The other end of the transverse sensor (15) is fixed to the second fixing point on the bottom surface of the beam (13); The side fixing point of the bridge bearing (12), the first fixing point on the bottom surface of the beam (13) and the second fixing point on the bottom surface of the beam (13) are used to form a geometric constraint relationship for calculating the longitudinal slip and the lateral displacement of the bridge bearing (12).

6. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, Control the inspection drone (32) to fly to the monitoring area of ​​the bridge support (12) according to the preset route, including: The inspection drone (32) is controlled by the drone base station (31) for take-off and landing, charging and data transmission. Control the inspection drone (32) to fly to multiple bridge support (12) monitoring points according to the preset three-dimensional route; Through the autonomous navigation and obstacle avoidance functions of the inspection drone (32), the inspection drone (32) is made to hover at the shooting position corresponding to the current bridge support (12) monitoring point; Acquiring high-resolution images of the color-changing photonic crystal sensor (2) includes: The high-resolution images are acquired by a high-definition camera (33) with a resolution of not less than 20 million pixels; The color-changing photonic crystal sensor (2) is illuminated by an LED ring light (34); The color-changing photonic crystal sensor (2) area in the high-resolution image is located by an image recognition algorithm, and the inspection drone (32) is controlled to adjust its hovering position so that the color-changing photonic crystal sensor (2) area is located at a preset position in the acquisition screen.

7. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, The high-resolution image is preprocessed and sensor region identified by the image processing system (35), and the color features and contour information of the color-changing photonic crystal sensor (2) are extracted, including: The high-resolution image is subjected to denoising, image enhancement, and color correction. Sensor region segmentation is performed on the preprocessed high-resolution image to determine the region of the color-changing photonic crystal sensor (2); Extract at least one of the RGB color value, hue value, saturation value, brightness value and structural color wavelength parameter of the region of the color-changing photonic crystal sensor (2) as the color feature; The geometric contour of the region of the color-changing photonic crystal sensor (2) is extracted as the contour information; After extracting the contour information of the color-changing photonic crystal sensor (2), the method further includes: Based on the contour information, determine whether the color-changing photonic crystal sensor (2) is twisted, partially detached, or obstructed by foreign objects; If the contour information indicates that the color-changing photonic crystal sensor (2) is twisted, partially detached, or obstructed by foreign objects, the corresponding monitoring data will be marked as suspicious data and a manual review prompt will be output.

8. The bridge support displacement monitoring method based on color-changing photonic crystal according to claim 1, characterized in that, The method for calculating the displacement of the bridge bearing (12) is as follows: The lateral slip distance Δx and longitudinal sliding distance Δy of bridge bearing (12) are calculated respectively: ； ； Where β and δ are calculated respectively: ； ； In the formula, Δx is the lateral displacement distance of the bridge bearing (12), Δy is the longitudinal sliding distance of the bridge bearing (12); a is the horizontal lateral distance between the fixed points A and B on the bottom surface of the beam (13), b is the horizontal longitudinal distance between the fixed points A and B on the bottom surface of the beam (13), L is the straight distance between the fixed points A and B on the bottom surface of the beam (13), h is the vertical distance between the fixed point O on the side of the bridge bearing (12) and the plane between the fixed points A and B on the bottom surface of the beam (13); l1 and l2 are the initial longitudinal sensor (14) OA length and the initial lateral sensor (15) OB length during installation, respectively; l3 and l4 are the lengths of the longitudinal sensor (14) OA' and the lateral sensor (15) OB' after displacement, respectively.

9. A bridge bearing displacement monitoring system, characterized in that, The system for performing the bridge bearing displacement monitoring method according to any one of claims 1 to 8, the system comprising: A color-changing photonic crystal sensor (2) is used to be installed between the bridge support (12) and the beam (13), and to generate tensile deformation and color feature change when the bridge support (12) and the beam (13) undergo relative displacement. The unmanned aerial vehicle (UAV) inspection system is used to fly to the monitoring area of ​​the bridge support (12) according to the preset route, collect high-resolution images of the color-changing photonic crystal sensor (2), and send the high-resolution images to the image processing system (35). Image processing system (35) is used to preprocess the high-resolution image and identify the sensor region, extract the color features and contour information of the color-changing photonic crystal sensor (2), invert the stretching length of the color-changing photonic crystal sensor (2) based on the color features, and calculate the bridge support displacement based on the stretching length and the geometric parameters when the sensor is initially installed. The image processing system (35) includes an image preprocessing module, a sensor positioning module, a color feature extraction module, a stretching length inversion module, a displacement calculation module, and an anomaly marking module.

10. The bridge bearing displacement monitoring system according to claim 9, characterized in that, The color-changing photonic crystal sensor (2) includes a longitudinal sensor (14) and a transverse sensor (15). The longitudinal sensor (14) is arranged longitudinally along the bridge bearing (12) to sense the longitudinal slippage of the bridge bearing (12); The lateral sensor (15) is arranged laterally along the bridge bearing (12) to sense the lateral displacement of the bridge bearing (12). One end of the longitudinal sensor (14) and the transverse sensor (15) are fixed to the side of the bridge support (12), and the other end is fixed to the bottom surface of the beam (13); The drone inspection system includes: The drone base station (31) is used to perform take-off and landing control, charging control and data transmission control for the inspection drone (32); The inspection drone (32) is used to fly to the monitoring area of ​​the bridge support (12) according to the preset route and hover at the shooting position corresponding to the monitoring point of the bridge support (12); A high-definition camera (33) is mounted on the inspection drone (32) to collect high-resolution images of the color-changing photonic crystal sensor (2); Lighting equipment, mounted on the inspection drone (32), is used to provide supplementary lighting for the color-changing photonic crystal sensor (2) when acquiring the high-resolution image; The image preprocessing module is used to perform noise reduction, image enhancement, and color correction on the high-resolution image. The sensor positioning module is used to identify and locate the region of the color-changing photonic crystal sensor (2) from the pre-processed high-resolution image; The color feature extraction module is used to extract at least one of RGB color value, hue value, saturation value, brightness value and structural color wavelength parameter from the region of the color-changing photonic crystal sensor (2); The stretching length inversion module is used to invert the current stretching length of the color-changing photonic crystal sensor (2) based on the color features and the pre-established mapping relationship between stretching length and color features. The displacement calculation module is used to calculate the displacement of the bridge support based on the current tensile length and the geometric parameters of the sensor at the time of initial installation; The anomaly marking module is used to determine whether the color-changing photonic crystal sensor (2) is twisted, partially detached or blocked by foreign objects based on the contour information, and to mark the corresponding monitoring data as suspicious data when an anomaly is found.

Images