Hybrid support tower concrete peeling monitoring method based on vision measurement and optical fiber sensing

Abstract

The invention relates to a hybrid support tower drum concrete peeling monitoring method based on vision measurement and optical fiber sensing, which comprises the following steps: S1, acquiring strain data of a weak area concrete surface in real time through an optical fiber strain sensing module arranged on the weak area concrete surface of the inner wall of a tower drum; and S2, when the strain data exceed a set strain threshold value, determining a tower drum abnormal area in which the strain data exceed the strain threshold value, then controlling a first camera module to photograph the tower drum abnormal area, and performing defect identification and classification analysis on the tower drum abnormal area according to obtained first image data. By arranging the optical fiber strain sensing module and the first camera shooting module, on the basis of a visual measurement and optical fiber sensing mode, automatic monitoring and rapid positioning of concrete peeling in the weak area of the inner wall of the mixed supporting tower drum are achieved, and the detection accuracy and the inspection efficiency are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hybrid support tower monitoring, and particularly relates to a hybrid support tower concrete spalling monitoring method based on visual measurement and optical fiber sensing. BACKGROUND

[0002] The hybrid support wind turbine is affected by various environmental factors and wind load cycles during service, and structural damages such as tower segment surface concrete cracking, spalling, erosion and exposed reinforcement often occur during the operation of the wind turbine, thereby causing the decrease of tower structure strength and durability and seriously affecting the bearing capacity and safety of the hybrid support structure.

[0003] At present, the surface defects of the hybrid support tower are generally checked and maintained regularly by manual inspection, but there are problems such as long time consumption, strong human subjectivity, narrow coverage and high cost. In recent years, the rapid development of unmanned aerial vehicles and machine vision has to some extent solved the semi-automatic inspection problem of the outer surface defects of the hybrid support tower, and significantly improved the detection accuracy and inspection efficiency. However, the detection of the inner surface defects of the hybrid support tower still remains in the stage of manual inspection. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a hybrid support tower concrete spalling monitoring method based on visual measurement and optical fiber sensing.

[0005] The technical scheme adopted by the present application to solve the technical problem is: a hybrid support tower concrete spalling monitoring method based on visual measurement and optical fiber sensing, comprising the following steps:

[0006] S1, acquiring strain data of a weak area of a tower in real time by arranging an optical fiber strain sensing module on a concrete surface of the weak area of the tower;

[0007] S2, when the strain data exceeds a set strain threshold, determining an abnormal area of the tower where the strain data exceeds the strain threshold, then controlling a first camera module to take a picture of the abnormal area of the tower, and performing defect identification and classification analysis on the abnormal area of the tower according to obtained first image data.

[0008] In an embodiment, the method further comprises:

[0009] S3, collecting vibration signals generated by object falling by arranging an optical fiber vibration sensing module array at the bottom of the tower, and recording the time when the vibration signals occur;

[0010] S4, when the vibration signal exceeds the set vibration threshold, determining the position of the abnormal vibration sensing module whose vibration signal exceeds the vibration threshold, controlling the second camera module to take a photo of the position of the abnormal vibration sensing module, and performing image recognition and classification on the falling object according to the obtained second image data.

[0011] In an embodiment, further comprising:

[0012] S5, according to the recognition result of the second image data, if the falling object is a concrete block and the fiber strain sensing module captures abnormal strain data, it is determined that the concrete block comes from the weak area of the inner wall of the tower drum, and the falling time, peeling area position and peeling area of the concrete block are generated.

[0013] In an embodiment, further comprising:

[0014] S6, according to the recognition result of the second image data, if the falling object is a concrete block and the strain data does not exceed the set strain threshold, it is determined that the concrete block comes from other areas of the inner wall of the tower drum, and the falling time of the concrete block is generated.

[0015] In an embodiment, further comprising:

[0016] By arranging the fiber temperature sensing module on the surface of the concrete in the weak area of the inner wall of the tower drum, the temperature data of the concrete surface is collected, and the strain data is corrected according to the temperature data to eliminate the strain change caused by temperature.

[0017] In an embodiment, the strain data is corrected based on the following formula:

[0018] Δλ b =K ξ *ε+K T *ΔT

[0019] In the formula, Δλ b is the central wavelength drift, K ξ is the strain sensitivity, K T is the temperature sensitivity, ΔT is the temperature change, and ε is the strain data.

[0020] In an embodiment, the fiber strain sensing module uses quasi-distributed optical cable;

[0021] The quasi-distributed optical cable includes a plurality of first parts and a plurality of second parts, the two ends of the first part are fixed on the adjacent two segments, and the two ends of the second part are connected to the first end of the adjacent two first parts or the second end of the adjacent two first parts; The first part is provided with a weak grating, and the weak grating is located between the segment connection area of the adjacent two segments.

[0022] In an embodiment, when the weak area is a tube sheet connection area of the inner wall of the tower drum, the first camera module is installed at a central area of the inner support platform of the tower drum, and the first camera module comprises a plurality of cameras.

[0023] In an embodiment, the array of fiber vibration sensing modules comprises a plurality of fiber grating vibration sensors connected in series, and the fiber grating vibration sensors are uniformly arranged along the circumferential direction of the tower drum wall at the bottom of the tower drum.

[0024] In an embodiment, the second camera module is installed at a central area of the bottom of the tower drum, and the second camera module comprises a plurality of cameras.

[0025] The implementation of the present application has the following beneficial effects: through the arrangement of the fiber strain sensing module and the first camera module, automatic monitoring and rapid positioning of concrete spalling of the weak area of the inner wall of the hybrid support tower drum are realized in a manner based on visual measurement and fiber sensing, and the accuracy and inspection efficiency of detection are significantly improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] The present application will be further described below with reference to the accompanying drawings and embodiments, in which:

[0027] Figure 1 is a flowchart of an embodiment of the present application, which is a hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing;

[0028] Figure 2 is a schematic diagram of the arrangement of the quasi-distributed optical cable in the inner wall of the hybrid support tower drum in an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of the arrangement of the monitoring equipment of the weak area in an embodiment of the present application;

[0030] Figure 4 is a schematic diagram of the calculation of the camera elevation angle in an embodiment of the present application;

[0031] Figure 5 is a schematic diagram of the arrangement of the monitoring equipment at the bottom of the tower drum in an embodiment of the present application. DETAILED DESCRIPTION

[0032] In order to have a clearer understanding of the technical features, objectives and effects of the present application, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, the terms “first”, “second”, etc. are only used for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features with “first”, “second”, etc. can explicitly or implicitly include one or more of the features. For ordinary skilled persons in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] As Figure 1 shown, in an embodiment of the mixed support tower drum concrete spalling monitoring method based on visual measurement and optical fiber sensing of the application, the following steps are included:

[0034] S1, by laying the optical fiber strain sensing module on the concrete surface of the weak area of the tower drum inner wall, real-time acquisition of the strain data of the weak area of the concrete surface.

[0035] The weak area in step S1 is mainly identified according to the design data, simulation results and operation and maintenance experience of the mixed support tower drum, mainly including the stress concentration area of the tower drum inner wall and the area prone to concrete spalling, such as the tower drum diameter transition section, transition section, tower drum door hole around, etc. These areas are prone to stress concentration, and under the coupling action of complex cyclic load and environmental factors, pipe piece concrete cracking, crushing and spalling phenomenon easily occurs. The optical fiber strain sensing module is arranged for the weak area of the tower drum inner wall, and the strain data of the concrete surface is collected in real time, which can significantly improve the efficiency and speed of concrete spalling monitoring.

[0036] In this embodiment, the optical fiber strain sensing module uses quasi-distributed optical cable. As an option, the quasi-distributed optical cable is engraved with a weak grating (wFBG) array, and the weak grating array is composed of a plurality of wFBGs with a spacing of 2m, a center wavelength of 1552nm and a reflectivity of 0.1%.

[0037] The pipe piece connection area refers to the key part for realizing structural connection, force transmission and sealing between adjacent pipe pieces, and in some cases, the pipe piece connection area of the mixed support tower drum is connected using concrete. For the pipe piece connection area, the laying method provided in this embodiment is that the quasi-distributed optical cable includes a plurality of first parts and a plurality of second parts, the two ends of the first part are fixed on the adjacent two pipe pieces respectively, and the two ends of the second part are connected with the first end of the adjacent two first parts or the second end of the adjacent two first parts. The first part is provided with a weak grating, and the weak grating is located in the pipe piece connection area between the adjacent two pipe pieces.

[0038] The quasi-distributed optical cable is engraved with a weak grating (wFBG) array, and the quasi-distributed optical cable is fixed on the tower drum, and the strain change is monitored in real time by the weak grating array, wherein the number of fixed points can be determined according to the spatial measurement resolution and the actual situation. For example, optical cable fixed points 2, 3, 6, 7, 10 and 1, 4, 5, 8, 9 are arranged on the upper and lower pipe pieces of the tower drum weak area respectively. Figure 2

[0039] ​In the first part of the cable is laid across the segmental connection area, the optical cable needs to be pre-stretched and then fixed, such as the cable 1-2, 3-4, 5-6, 7-8, 9-10, to ensure that the strain data of the concrete surface of the segmental connection area is accurately measured. When the concrete between the two vertical cable fixing points cracks or peels off, the first part between the fixing points will be stretched and deformed, causing the wFBG center wavelength to drift. By synchronously demodulating the frequency and position, the wavelength drift amount can be calculated, and the strain data of the corresponding position of the tower drum can be obtained, so that the accurate positioning of the concrete peeling position or deformation position can be realized. In addition, when the first part is laid, the wFBG should be kept in the middle position between the two adjacent vertical cable fixing points. The second part on the same segment does not need to be pre-stretched and is naturally curved, such as the cable 2-3, 4-5, 6-7, 8-9.

[0040] It can be understood that for other weak areas, the layout mode of the quasi-distributed optical cable can be adjusted according to actual monitoring needs.

[0041] In an embodiment, the method further comprises: collecting temperature data of the concrete surface by the optical fiber temperature sensing module laid on the concrete surface of the weak area of the inner wall of the tower drum, correcting the strain data according to the temperature data, and eliminating the strain change caused by the temperature.

[0042] Since temperature changes can also cause the optical cable to deform, the strain data needs to be corrected according to the temperature data. The optical fiber temperature sensing module uses a temperature compensation wFBG. The optical fiber temperature sensing module is connected in series at the tail end of the optical fiber strain sensing module and contacts the concrete surface. The optical fiber temperature sensing module is not sensitive to external strain changes and only senses temperature changes, which is used to compensate for the influence of environmental temperature on the wavelength change of the optical fiber strain sensing module.

[0043] Wherein, the strain data is corrected based on the following formula:

[0044] Δλ b = K ξ * ε + K ξ * ΔT

[0045] In the formula, Δλ b is the center wavelength drift amount, K ξ is the strain sensitivity of the optical fiber strain sensing module, K T is the temperature sensitivity of the optical fiber temperature sensing module, ΔT is the temperature change amount of the concrete surface, and ε is the strain data of the concrete surface.

[0046] S2, when the strain data exceeds the set strain threshold, determining an abnormal area of the tower drum whose strain data exceeds the strain threshold, and then controlling the first camera module to take a photo of the abnormal area of the tower drum, and performing defect identification and classification analysis on the abnormal area of the tower drum according to the obtained first image data.

[0047] When the abnormal area of the tower drum has concrete spalling or deformation, the strain data of the abnormal area exceeds the strain threshold, the position information of the weak light grating that monitors the abnormal strain data is obtained, the elevation angle and the deflection angle of the first camera module are calculated, and then the first camera module is controlled to take a photo of the abnormal area of the tower drum and upload the photo. The defect identification is based on an image recognition model of YOLOv8 or other algorithms, and the model is trained based on a defect data set of the tower drum surface. The model can realize classification and positioning of diseases such as concrete spalling, cracking, and water seepage, and output the type of the disease, so as to realize monitoring and early warning of concrete cracking before concrete spalling of the tower drum, and enable the operation and maintenance personnel to intervene in the operation and maintenance of the tower drum defects in advance. Further, based on the output result, it can be determined whether the weak area has concrete spalling, and automatic monitoring and rapid positioning of concrete spalling of the weak area of the inner wall of the hybrid support tower drum are realized, which significantly improves the inspection efficiency. Through camera linkage and image recognition algorithm, secondary identification of the abnormal area of the tower drum is performed, false positives are avoided, and the recognition accuracy of the concrete spalling of the tower drum is improved.

[0048] Alternatively, when the weak area is a segment connection area of the inner wall of the tower drum, the first camera module is installed at the center area of the inner support platform of the tower drum, and the first camera module includes a plurality of cameras.

[0049] The support platform is a horizontal load-bearing structure installed inside the tower drum, and is usually located at different height layers of the tower drum and is fixed to the tower drum wall through platform support rods or other connecting members. As shown in FIG. 1, the first camera module includes three high-definition cameras, each of which monitors 1 / 3 of the circumference of the tower drum. The cameras also have an automatic light compensation function, and can still take high-definition photos of the tower drum wall when the line of sight is poor. Figure 3

[0050] As shown in FIG. 2, the heights of the weak light grating and the camera from the support platform are H and h respectively, the distance between the camera and the tower drum wall is L, and when the camera is installed at the center of the support platform, L is the radius R of the support platform of the tower drum. The elevation angle a of the camera can be obtained by the following formula: Figure 4

[0051] The deflection angle θ of the camera can be determined according to the layout position of the quasi-distributed optical cable. For example, the quasi-distributed optical cable is uniformly laid at a segment connection area, and 36 weak light gratings are uniformly engraved on the quasi-distributed optical cable, and the deflection angle between two adjacent weak light gratings is 10°.

[0052]

[0053] ​​Further, the method further comprises:

[0054] S3, collecting the vibration signal generated by the object falling through the fiber vibration sensing module array arranged at the bottom of the tower drum, and recording the time when the vibration signal occurs.

[0055] In an embodiment, the fiber vibration sensing module array is formed by a plurality of fiber grating vibration sensors connected in series, and the fiber grating vibration sensors are uniformly arranged along the circumferential direction of the tower drum at the bottom of the tower drum. Specifically, the fiber grating vibration sensors are connected in series through sensing optical cables in sequence, and the number of fiber grating vibration sensors is determined according to actual monitoring requirements. The falling of concrete blocks or other objects to the bottom of the tower drum will cause a vibration shock signal, and the fiber grating vibration sensor can capture the vibration signal generated by the falling and record the capture time as the time when the vibration signal occurs.

[0056] S4, when the vibration signal exceeds the set vibration threshold, determining the position of the abnormal vibration sensing module whose vibration signal exceeds the vibration threshold, controlling the second camera module to take a photo of the position of the abnormal vibration sensing module, and performing image recognition and classification on the falling object according to the obtained second image data.

[0057] The abnormal vibration sensing module is a fiber grating vibration sensor whose collected vibration signal exceeds the vibration threshold. When the vibration signal exceeds the vibration threshold, it is preliminarily determined as a suspected concrete spalling event, and the object falls near the abnormal vibration sensing module. When the vibration signals collected by multiple fiber grating vibration sensors exceed the vibration threshold, the fiber grating vibration sensor with the largest vibration signal amplitude is selected as the abnormal vibration sensing module. According to the position of the abnormal vibration sensing module, the elevation and deflection angle of the second camera module are controlled, and then the second camera module is controlled to take a photo of the abnormal area of the tower drum and upload it. Then, the falling object is identified and classified according to the second image data, to determine whether the falling object is a concrete block. In this embodiment, an image recognition model based on YOLOv8 or other algorithms can be used.

[0058] As shown in Figure 5 The second camera module is installed in the central area at the bottom of the tower drum, and the second camera module includes a plurality of cameras, such as three or four. The number of cameras can be specifically set as needed. The calculation scheme of the elevation and deflection angle of the second camera module is similar to that of the first camera module, which will not be described here.

[0059] Further, the method further comprises:

[0060] S5, according to the identification result of the second image data, if the falling object is a concrete block and the fiber strain sensing module captures abnormal strain data, it is determined that the concrete block comes from the weak area of the inner wall of the tower drum, and the falling time, spalling area position and spalling area of the concrete block are generated.

[0061] It can be understood that, within a certain time range, if the falling object is identified as a concrete block, the fiber strain sensing module arranged in the weak area captures abnormal strain data, and it is determined that the defect of the abnormal area of the tower drum is concrete peeling, which indicates that the cause of the phenomenon is that the concrete block in the weak area of the inner wall of the tower drum peels off and falls to the bottom of the tower drum after passing through the support platform or other blocking structure. Therefore, by combining the fiber sensing and visual measurement technology, the embodiment can generate the falling time of the concrete block according to the time of the vibration signal, determine the peeling area position according to the abnormal strain data, and identify the peeling area according to the first image data.

[0062] S6, according to the identification result of the second image data, if the falling object is a concrete block and the strain data does not exceed the set strain threshold, it is determined that the concrete block comes from other areas of the inner wall of the tower drum, and the falling time of the concrete block is generated.

[0063] It can be understood that, if the falling object is identified as a concrete block, but there is no strain data exceeding the strain threshold, it indicates that the concrete block does not come from the weak area of the inner wall of the tower drum, but comes from other concrete segment areas of the inner wall of the tower drum, and the falling time of the concrete block is generated according to the time of the abnormal vibration signal.

[0064] It can be understood that the above embodiments only express the preferred embodiments of the present application, which are described in detail and in detail, but cannot be understood as a limitation on the scope of the patent of the present application; It should be pointed out that for ordinary skilled in the art, the above technical features can be freely combined without departing from the concept of the present application, and some deformations and improvements can be made, which belong to the protection scope of the present application; Therefore, any equivalent transformation and modification within the scope of the claims of the present application shall belong to the scope of the claims of the present application.

Claims

1. A hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing, characterized by, The method comprises the following steps: S1, acquiring strain data of the weak area of the tower drum in real time through the optical fiber strain sensing module arranged on the surface of the concrete of the weak area of the tower drum; S2, when the strain data exceeds the set strain threshold, determining the abnormal area of the tower drum where the strain data exceeds the strain threshold, and then controlling the first camera module to take a photo of the abnormal area of the tower drum, and performing defect identification and classification analysis on the abnormal area of the tower drum according to the obtained first image data.

2. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 1, characterized in that, Further comprising: S3, collecting vibration signals generated by the falling object through the array of optical fiber vibration sensing modules arranged at the bottom of the tower drum, and recording the time when the vibration signals occur; S4, when the vibration signals exceed the set vibration threshold, determining the position of the abnormal vibration sensing module where the vibration signals exceed the vibration threshold, controlling the second camera module to take a photo of the position of the abnormal vibration sensing module, and performing image recognition and classification on the falling object according to the obtained second image data.

3. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 2, characterized in that, Further comprising: S5, according to the recognition result of the second image data, if the falling object is a concrete block and the optical fiber strain sensing module captures abnormal strain data, it is determined that the concrete block comes from the weak area of the inner wall of the tower drum, and the falling time, peeling area position and peeling area of the concrete block are generated.

4. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 2, characterized in that, Further comprising: S6, according to the recognition result of the second image data, if the falling object is a concrete block and the strain data does not exceed the set strain threshold, it is determined that the concrete block comes from other areas of the inner wall of the tower drum, and the falling time of the concrete block is generated.

5. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 1, characterized in that, Further comprising: The optical fiber temperature sensing module arranged on the surface of the concrete of the weak area of the inner wall of the tower drum is used to collect temperature data of the surface of the concrete, and the strain data is corrected according to the temperature data to eliminate the strain change caused by temperature.

6. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 5, characterized in that, The strain data is corrected based on the following formula: Δλ b = K ξ * ε + K T * ΔT In the formula, Δλ b is a central wavelength shift amount, K ξ is a strain sensitivity, K T is a temperature sensitivity, ΔT is a temperature change amount, and ε is a strain data.

7. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 1, characterized in that, The optical fiber strain sensing module uses quasi-distributed optical cable; The quasi-distributed optical cable comprises a plurality of first parts and a plurality of second parts, the two ends of the first part are fixed on the adjacent two segments, and the two ends of the second part are connected to the first end of the adjacent two first parts or the second end of the adjacent two first parts; a weak grating is arranged in the first part, and the weak grating is located in the segment connection area between the adjacent two segments.

8. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 1, characterized in that, When the weak area is the segment connection area of the inner wall of the tower drum, the first camera module is installed in the central area of the inner support platform of the tower drum, and the first camera module comprises a plurality of cameras.

9. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 2, characterized in that, The array of optical fiber vibration sensing modules is connected in series by a plurality of fiber grating vibration sensors, and the fiber grating vibration sensors are uniformly arranged along the circumferential direction of the tower drum wall at the bottom of the tower drum.

10. The hybrid support tower drum concrete spalling monitoring method based on visual measurement and fiber sensing according to claim 2, characterized in that, The second camera module is installed in the central area at the bottom of the tower drum, and the second camera module comprises a plurality of cameras.

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