Portable crack width measuring device and method for non-flat wall surface

Abstract

The invention discloses a portable crack width measuring device and method for a non-flat wall surface. The portable crack width measuring device comprises an image acquisition unit, a width measuring unit and a processing unit, the width measuring unit comprises a rod-shaped lens module, a photosensitive module and a moving mechanism; the rod-shaped lens module comprises a rod-shaped lens array, a telescopic mechanism and light-transmitting glass, and the rod-shaped lens array is driven by the telescopic mechanism to move, so that the light-transmitting glass is in contact with the wall surface; the moving mechanism comprises structural parts arranged at the two ends of the photosensitive module, a sliding rail for bearing the structural parts and a motor for controlling the structural parts to move on the sliding rail, and the photosensitive module is driven to collect crack brightness curves under different focal lengths; and the processing unit identifies the crack position according to the crack image, selects a focusing brightness curve from the crack brightness curves, performs brightness self-compensation on the focusing brightness curve, and calculates the crack width after merging. The problems that the measurement result is influenced by a concave-convex fluctuating wall surface, misjudgment is caused by wall surface pits / protrusions, the measurement range is small, and the precision is low are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of crack width measurement, and particularly to a portable crack width measurement device and method for non-flat walls. Background Art

[0002] The statements in this part merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Concrete is widely used in the field of engineering construction. Due to the influence of factors such as load stress and steel bar corrosion, cracks are likely to occur on the concrete surface, posing potential hazards to the healthy service of engineering facilities. Regular inspection of concrete building facilities and targeted repair of cracks with potential safety hazards are important measures to ensure project safety. During the inspection of concrete buildings, due to reasons such as a large amount of building inspection work, limited working space, and large manual measurement errors, high-efficiency, miniaturized, and high-precision portable crack width measurement devices are the development trend of crack width measurement devices.

[0004] However, existing portable crack width measurement devices based on contact image sensors (CIS) are difficult to adapt to uneven walls, easily causing measurement errors. Moreover, due to the limitation of single-row pixels, the device cannot distinguish interference such as wall holes and small protrusions, easily resulting in misjudgment. Existing micro-camera portable crack width measurement devices must be equipped with high-precision, high-resolution cameras and high-performance control chips, which are expensive and still have problems such as a small measurement range and low precision. Due to the small measurement range, the camera must be accurately aligned with the crack position, resulting in low usage efficiency. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a portable crack width measurement device and method for non-flat walls. The designed rod lens module can independently contract back and forth, adapt to uneven walls and maintain focus, and use the crack image obtained by the image acquisition unit to provide crack position information for the single-row pixel photosensitive chip in the width measurement unit, solving problems such as the influence of uneven walls on the crack width measurement result during actual crack measurement, misjudgment of the crack area caused by wall holes / protrusions, and the small measurement range and low precision of existing devices.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a portable crack width measurement device for non-flat walls, including: a housing, and an image acquisition unit, a width measurement unit, and a processing unit provided on the housing;

[0008] The image acquisition unit is used to obtain a crack image;

[0009] The width measurement unit includes at least two rows of rod lens modules, with at least two rod lens modules arranged side by side in the same direction in each row, a photosensitive module and a moving mechanism located directly behind the rod lens modules;

[0010] Each rod lens module includes a rod lens array, a module fixing mechanism provided on a housing, a telescopic mechanism provided inside the module fixing mechanism and connected to the rod lens array, and a light-transmitting glass provided on the rod lens array, so as to drive the movement of the rod lens array through the telescopic mechanism, thereby bringing the light-transmitting glass into contact with the wall surface;

[0011] The moving mechanism includes structural members provided at both ends of the photosensitive module, a slide rail for carrying the structural members, and a motor for controlling the movement of the structural members on the slide rail, so as to drive the photosensitive module to collect the crack brightness curves at different focal lengths;

[0012] The processing unit receives the crack image and the crack brightness curve, and is configured to identify the crack position information according to the crack image, select the focusing brightness curves of all rod lens modules from the crack brightness curve, perform brightness self-compensation and merging on the focusing brightness curves, and calculate the crack width in combination with the crack position information.

[0013] As an alternative implementation, a reserved groove is provided inside the module fixing mechanism, the telescopic mechanism is provided in the reserved groove, the telescopic mechanism includes a spring, a reset rod and a baffle, the reset rod passes through the spring and is provided in the reserved groove, the baffle is provided at the top of the rod lens array, the baffle is pressed by the reset rod and fits against the inner wall of the reserved groove, and by compressing the spring with the baffle, each rod lens array moves telescopically independently, so that the light-transmitting glass is in contact with the wall surface.

[0014] As an alternative implementation, the thickness of the light-transmitting glass is set to the focal length of the rod lens array.

[0015] As an alternative implementation, the two rows of rod lens modules face the same direction, the lower row of rod lens modules is in an inverted state, the rod lens arrays in the two rows of rod lens modules are in contact with each other, and the two rows of rod lens modules are arranged in a staggered "pin" shape.

[0016] As an alternative implementation, the photosensitive module includes at least two photosensitive chips and a first circuit board, the at least two photosensitive chips are arranged in parallel on the first circuit board, and the rod lens array of one row of rod lens modules corresponds to one photosensitive chip.

[0017] As an alternative implementation, the housing includes a scanning gun housing and a scanning head panel, the scanning head panel is installed at the head of the scanning gun housing, an image acquisition unit and a width measurement unit are installed on the scanning head panel, and the light-transmitting glass protrudes from the scanning head panel.

[0018] As an alternative embodiment, the process of selecting the focus brightness curve includes: intercepting the crack brightness curves of each rod lens module at different focal lengths, respectively calculating the first derivative array and the corresponding derivative standard deviation; selecting the set of crack brightness curves with the largest standard deviation as the focus brightness curve of the current rod lens module.

[0019] As an alternative embodiment, the process of brightness self-compensation and merging includes: performing normalization processing on the focus brightness curve to obtain a normalized brightness curve with a mean of zero, splicing the normalized brightness curves row by row, and using the normalized brightness curve at the same position in another row to splice the missing part of the normalized brightness curve formed at the junction of adjacent rod lens modules, and introducing an offset coefficient during splicing to make the starting point of the normalized brightness curve at the missing part coincide with the ending point of the previous normalized brightness curve, thereby forming at least two complete focus brightness curves.

[0020] As an alternative embodiment, the process of calculating the crack width in combination with the crack position information includes:

[0021] The crack position information includes the abscissa of the lower end position of the crack and the width of the crack recognition frame. Based on this, a crack distribution probability function is established. After normalizing the focus brightness curve, its complementary curve is multiplied by the crack distribution probability function to obtain a processed curve. The position corresponding to the minimum value of the processed curve is the true crack position;

[0022] Calculate the average value of the focus brightness curve, calculate the number of pixel points lower than the average value at the left and right ends of the true crack position of the focus brightness curve, and multiply the obtained number of pixel points by the pixel width to obtain the crack width.

[0023] As an alternative embodiment, a set of crack widths is obtained based on the focus brightness curve of each row of rod lens modules, and the final crack width is the average value of each group of crack widths.

[0024] In a second aspect, the present invention provides a measurement method for a portable crack width measurement device for a non-flat wall surface described in the first aspect, including:

[0025] Move the portable crack width measurement device above the surface of the crack to be measured, and keep the rod lens module perpendicular to the crack direction;

[0026] Press the scanning head panel against the surface of the crack to be measured, so as to compress the spring through the baffle, drive each rod lens array to move separately and telescopically, so that the light-transmitting glass contacts the wall surface;

[0027] Capture a crack image through the image acquisition unit, and collect the crack brightness curves at different focal lengths by driving the photosensitive module;

[0028] Identify the crack position information based on the crack image. Select the focus brightness curves of all rod lens modules from the crack brightness curve. After performing brightness self-compensation and merging on the focus brightness curves, calculate the crack width in combination with the crack position information.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] The present invention provides a portable crack width measurement device and method for non-flat walls. During the actual measurement process, the scanning head panel is closely attached to the wall where the crack is located. The two rows of rod lens modules of the width measurement unit are used to make the measurement adapt to the uneven crack wall surface. The telescopic mechanism in the rod lens module is used to keep each rod lens array in focus with the wall. The position of the photosensitive chip is controlled by a micro stepping motor to obtain the crack brightness curve during focusing. Then, the crack image is obtained from the image acquisition unit, the crack position is obtained through the built-in crack detection algorithm, and further the position of the crack in the rod lens module is deduced. The brightness curve of the rod lens module at this specific position is processed and analyzed to obtain the crack width. This solves the problems that the uneven wall surface affects the crack width measurement result during the actual crack measurement, the wall holes / protrusions cause misjudgment of the crack area, and the existing equipment has a small measurement range and low accuracy.

[0031] In the present invention, through the image acquisition unit and the width measurement unit installed on the scanning head panel, during the actual measurement, the portable device is closely attached to the area near the crack. The crack image obtained by the image acquisition unit provides the crack position information for the single-row pixel photosensitive chip in the width measurement unit. The width measurement unit is used to measure the crack width. Compared with the micro-camera device that needs to be accurately aligned with the crack for use, the present invention is convenient and fast to use, only needs to be roughly aligned, and has a large measurement range and high accuracy.

[0032] The present invention improves the traditional long-strip lens array of CIS by segmentation to form independent rod lens modules. The rod lens array of each rod lens module can independently contract forward and backward. It contracts backward in the wall protrusion area and extends forward in the wall depression area. The telescopic mechanism is used to keep each part of the rod lens array in focus with the wall, making the device adapt to the uneven wall surface and maintain focus, effectively solving the problem that the crack width measurement device is easily affected by the uneven and undulating wall surface, resulting in measurement errors.

[0033] The present invention captures the crack area image through the image acquisition unit and identifies the crack position through the crack detection algorithm, providing a reference basis for the crack position for the width measurement unit, effectively avoiding the problem that the CIS-based crack width measurement device cannot distinguish the interference of wall holes, small protrusions, etc., and further ensuring the accuracy of the crack width data.

[0034] Through the display screen of the portable device, after it is connected to the image acquisition unit, the width measurement unit, and the processing unit, during the actual measurement, it is only necessary to observe the measurement data displayed on its display screen, which further reduces the workload of on-site measurement staff and makes the device more user-friendly during use.

[0035] Advantages of additional aspects of the present invention will be partly given in the following description, partly will become obvious from the following description, or will be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained according to the provided drawings.

[0037] Figure 1 Schematic diagram of the overall structure of the portable crack width measurement device for non-flat walls provided in Embodiment 1 of the present invention;

[0038] Figure 2 Schematic diagram of the overall side view structure of the portable crack width measurement device for non-flat walls provided in Embodiment 1 of the present invention;

[0039] Figure 3 Schematic diagram of the internal structure of the portable crack width measurement device for non-flat walls provided in Embodiment 1 of the present invention;

[0040] Figure 4 For Figure 3 Enlarged structure schematic diagram at A in

[0041] Figure 5 Schematic diagram of the structure of the rod lens module provided in Embodiment 1 of the present invention;

[0042] Figure 6 Schematic diagram of the structure of the photosensitive module and its moving mechanism provided in Embodiment 1 of the present invention;

[0043] Figure 7 Schematic diagram of the shape and distribution of the photosensitive chips provided in Embodiment 1 of the present invention;

[0044] Figure 8 Schematic diagram of the defocusing and focusing conditions during the imaging of the rod lens array provided in Embodiment 1 of the present invention;

[0045] Figure 9 Schematic diagram of the processing method flow of the processing unit provided in Embodiment 1 of the present invention;

[0046] Wherein: 1. The housing of the barcode scanner; 2. The scanning head panel; 3. The image acquisition unit; 4. The width measurement unit; 5. The camera; 6. The fill light; 7. The light bar; 8. The rod lens module; 9. The photosensitive chip; 10. The module fixing mechanism; 11. The rod lens array; 12. The transparent glass; 13. The reserved groove; 14. The spring; 15. The reset rod; 16. The baffle; 17. The first circuit board; 18. The nut sleeve structural member; 19. The threaded rod; 20. The micro stepping motor; 21. The slider; 22. The slide rail; 23. The second circuit board; 24. The battery; 25. The measurement button; 26. The display screen; 27. The handle; 28. The out-of-focus plane; 29. The in-focus plane; 30. The out-of-focus curve; 31. The in-focus curve. Specific embodiments

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0048] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0049] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments of the present invention. As used herein, unless the context clearly indicates otherwise, the singular forms are also intended to include the plural forms. In addition, it should be understood that the terms "comprising" and "including" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0050] In the case of no conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0051] Embodiment 1

[0052] This embodiment provides a portable crack width measurement device for non-flat walls, including: a housing and an image acquisition unit, a width measurement unit, and a processing unit provided on the housing;

[0053] The image acquisition unit is used to acquire a crack image;

[0054] The width measurement unit includes at least two rows and at least two rod lens modules arranged side by side in the same direction in each row, and a photosensitive module and a moving mechanism located directly behind the rod lens modules;

[0055] Each rod lens module includes a rod lens array, a module fixing mechanism provided on the housing, a telescopic mechanism provided inside the module fixing mechanism and connected to the rod lens array, and a light-transmitting glass provided on the rod lens array, so as to drive the movement of the rod lens array through the telescopic mechanism, thereby bringing the light-transmitting glass into contact with the wall surface;

[0056] The moving mechanism includes structural members provided at both ends of the photosensitive module, a slide rail for carrying the structural members, and a motor for controlling the movement of the structural members on the slide rail, so as to drive the photosensitive module to collect the crack brightness curves at different focal lengths;

[0057] The processing unit receives the crack image and the crack brightness curve, and is configured to identify the crack position information according to the crack image, select the focusing brightness curves of all the rod lens modules from the crack brightness curve, perform brightness self-compensation and merging on the focusing brightness curves, and then calculate the crack width in combination with the crack position information.

[0058] As Figure 1 shown, the housing includes a scanning gun housing 1 and a scanning head panel 2. The scanning head panel 2 is installed at the head of the scanning gun housing 1, and an image acquisition unit 3 for collecting crack images and a width measurement unit 4 for measuring the crack width are installed on the scanning head panel 2.

[0059] As Figure 2 shown, a battery 24, a measurement button 25 and a display screen 26 are installed inside the scanning gun housing 1. The battery 24 and the measurement button 25 are installed at the handle 27 of the scanning gun housing 1, and the display screen 26 is installed behind the head of the scanning gun housing 1.

[0060] In this embodiment, the image acquisition unit 3 includes a camera 5 fixedly connected to the scanning head panel 2 and fill lights 6 provided on the left and right sides of the camera 5. The camera 5 is used to capture the crack image for detecting and positioning the crack position.

[0061] As Figure 3 shown, the width measurement unit 4 includes a light bar 7, a rod lens module 8, a photosensitive module and a moving mechanism; the width measurement unit 4 is used to obtain the crack brightness curve, and select, splice and process the brightness curve through the built-in chip algorithm to obtain the crack width information.

[0062] Exemplarily, the light bar 7 is used to provide supplementary light for the width measurement unit 4, so that the rod lens module 8 can receive stable wall reflected light, and an LED light bar can be used.

[0063] As Figures 3 - 5As shown in the figure, the rod lens module 8 is a miniature self-adhesive rod lens module, specifically including: a rod lens array 11, a module fixing mechanism 10 fixed on the scanning head panel 2, a telescopic mechanism arranged inside the module fixing mechanism 10 and connected to the rod lens array 11, and a light-transmitting glass 12 arranged on the rod lens array 11;

[0064] A reserved groove 13 is formed inside the module fixing mechanism 10, and a telescopic mechanism is installed inside the reserved groove 13. The telescopic mechanism includes a spring 14, a reset rod 15, and a baffle 16. The reset rod 15 passes through the spring 14 and is arranged in the reserved groove 13; a baffle 16 is provided at the top of the rod lens array 11, and the baffle 16 is pressed by the reset rod 15 and fits against the inner wall of the reserved groove 13. A cylindrical hole is formed behind the reserved groove 13, and the other end of the reset rod 15 passes through the cylindrical hole behind the reserved groove 13, so that the reset rod 15 can reciprocate in the cylindrical hole; the light-transmitting glass 12 is fixed to the rod lens array 11, and the thickness of the light-transmitting glass 12 is set to the focal length of the rod lens array 11.

[0065] As Figures 3 - 4 shown in the figure, there are multiple (at least two) rod lens modules 8, which are arranged in two rows on the scanning head panel 2. The multiple rod lens modules 8 in the same row are arranged side by side in the same direction, and the two rows of rod lens modules 8 face the same direction. The light-transmitting glass 12 protrudes from the scanning head panel 2; the lower row of rod lens modules 8 is in an inverted state, and the rod lens arrays 11 in the two rows of rod lens modules 8 are in contact with each other; the two rows of rod lens modules 8 are arranged in a staggered "pin" shape.

[0066] In order to enable the measurement to adapt to uneven cracked walls, in this embodiment, the rod lens modules 8 are arranged side by side in the same direction, and each rod lens module 8 in each row can be individually telescoped and moved, so as to ensure that each rod lens module 8 can contact the wall, and further ensure that the entire row of rod lens modules 8 can fit the undulating wall in the arrangement direction. Moreover, the rod lens array 11 in each rod lens module 8 and the wall are in contact through the light-transmitting glass 12, and the thickness of the light-transmitting glass 12 is the focal length of the rod lens array 11, thus ensuring that each rod lens array 11 is in focus with the wall and avoiding imaging blurring caused by defocusing between the lens and the wall.

[0067] The specific operation process is as follows: When the rod lens module is in contact with the undulating wall, for the protruding wall, by applying pressure to the device, the light-transmitting glass is pressed to contact the wall, thereby driving the baffle to compress the spring, and then driving the rod lens array to move backward to make the light-transmitting glass better contact the wall; for the sunken wall, the spring resets, and the light-transmitting glass protrudes from the scanning head panel and extends into the sunken wall to contact the wall.

[0068] Due to a certain data acquisition blind area between adjacent single-row rod lens modules 8, there may be a situation where a crack happens to be located between the rod lens modules 8, which easily causes missing crack data and errors. To address this problem, in this embodiment, the double-row rod lens modules 8 are arranged in a staggered "pin" shape, and the blind area of the single-row rod lens module 8 is the central acquisition area of the other row of rod lens modules 8, so that there is no acquisition blind area within the entire width measurement unit 4.

[0069] As Figures 6 - 7 shown, the photosensitive module is located inside the scanning head panel 2, behind the rod lens module, and includes a photosensitive chip 9 and a first circuit board 17. The photosensitive chip 9 is in a strip-shaped structure, with two installed in total. The two photosensitive chips 9 are arranged in parallel on the first circuit board 17; and the rod lens arrays 11 of the two rows of rod lens modules 8 respectively correspond to the two photosensitive chips 9. The photosensitive chip 9 is located directly behind the rod lens array 11 of the rod lens module 8 and has a certain distance from the rod lens array 11.

[0070] As Figure 6 shown, the moving mechanism includes a nut sleeve structure 18, a threaded rod 19, a micro stepping motor 20, a slider 21, and a slide rail 22; nut sleeve structures 18 are installed on both sides at the rear of the first circuit board 17. The rear of the nut sleeve structure 18 meshes with the threaded rod 19 of the micro stepping motor 20. The nut sleeve structures 18 on both sides and the micro stepping motor 20 are symmetrically installed with each other, and the bottoms of the nut sleeve structures 18 on both sides are fixed to the sliders 21 on both sides. The bottoms of the sliders 21 are connected to the slide rail 22.

[0071] During the measurement of the crack width on an uneven wall surface, in this embodiment, the rod lens module 8 that can be individually telescoped and moved is set to ensure that each rod lens array 11 is in focus with the wall surface. However, since the entire row of rod lens modules 8 uses the same photosensitive chip 9, the telescoping and moving degrees of the rod lens modules 8 at different positions in the same row are different, resulting in a defocus phenomenon between the rod lens array 11 and the photosensitive chip 9. To further ensure that each rod lens array 11 is in focus with the photosensitive chip 9, it is necessary to implement the above technical solution, specifically:

[0072] When the two rows of rod lens modules 8 are attached to the undulating wall surface, by controlling the micro stepping motor 20 to rotate a fixed angle, the threaded rod 19 then rotates a certain angle, driving the nut sleeve structure 18 and the first circuit board 17 to move forward (or backward) by a certain distance, thereby realizing the change of the front and rear positions of the photosensitive chip 9. Thus, the crack brightness curve of the rod lens module 8 at this distance is collected, and the first circuit board 17 records the rotation angle of the micro stepping motor 20 at this distance, and a set of data acquisition of the image distance can be completed; continuously controlling the micro stepping motor 20 to rotate different angles can complete the acquisition of the crack brightness curves at multiple image distances, that is, ensure that the crack brightness curves of each rod lens array 11 and the photosensitive chip 9 at different distances are recorded, including the crack brightness curve during focusing. Through the subsequent focusing brightness curve selection algorithm, the focusing brightness curves of all rod lens modules 8 can be obtained, and then accurate data can be provided for the subsequent crack width measurement.

[0073] As Figure 3 shown, a second circuit board 23 is fixedly installed inside the scanning gun housing 1. The chip inside the second circuit board 23 has a crack detection algorithm, a focusing brightness curve selection algorithm, a brightness curve self-compensation algorithm, and a crack width measurement algorithm, and the second circuit board 23 is connected to the first circuit board 17, the image acquisition unit 3, and the micro stepping motor 20.

[0074] As Figure 9 shown, specifically:

[0075] (1) The crack detection algorithm is a lightweight crack detection neural network that can be transplanted to embedded devices and is currently available.

[0076] (2) As Figure 8 shown in (a)-(c) of, in order to select the focusing brightness curve from all the collected crack brightness curves and obtain the crack data under accurate focusing conditions, this embodiment uses the difference between the focusing curve 31 and the defocus curve 30 for selection. In the defocus case, the crack brightness curve collected on the defocus plane 28 has a blurred phenomenon, the curve details will be weakened, and the overall smoothness is better; in the focusing case, the local details of the crack brightness curve collected on the focusing plane 29 are prominent, and the curve volatility is larger.

[0077] Based on the above principle, a focusing brightness curve selection algorithm is proposed. The focusing brightness curve selection algorithm uses the difference between the focusing curve and the defocus curve for selection;

[0078] First, intercept the crack brightness curve l d (x) of each group of rod lens modules 8 at different image distances, and calculate its first derivative array l' d (x) and the corresponding derivative standard deviation σ:

[0079]

[0080] where x i is the (i + 1)-th pixel position on the rod lens module 8; x0 is the 1st pixel position on the rod lens module 8; l' d (x0) is the first derivative of the crack brightness curve at x0 when the image distance is d; l' d (x i ) is the first derivative of the crack brightness curve at x i ;

[0081] Then, select a set of crack brightness curves with the largest standard deviation (the largest volatility) as the focus brightness curve of the rod lens module 8

[0082] (3) The brightness curve self-compensation algorithm performs brightness self-compensation and merging on the focus brightness curves of all rod lens modules 8 and merges them.

[0083] To eliminate the differences between the crack brightness curves of different rod lens modules and the errors caused by the boundaries of the rod lens modules during curve merging, first process the focus brightness curves through z-score standardization to obtain a standardized brightness curve with a mean of zero At this time, the brightness of each curve is at the same level, eliminating the differences between the brightness curves of different rod lens modules.

[0084] Then, splice the processed standardized brightness curves row by row. The missing standardized brightness curves formed at the junctions of adjacent rod lens modules 8 are spliced using the standardized brightness curves at the same position in another row to fill the missing brightness curves at the module junctions. An offset coefficient is introduced during splicing to make the starting point of the standardized brightness curve at the missing part coincide with the ending point of the previous standardized brightness curve, forming two complete focus brightness curves L1(x) and L2(x), eliminating the errors caused by the boundaries of the rod lens modules during curve merging;

[0085]

[0086] where α and β are offset coefficients.

[0087] (4) The crack width measurement algorithm calculates the crack width using the focus brightness curve and the crack position.

[0088] First, obtain the abscissa x of the lower end position of the crack through the crack detection algorithm crackand the width d of the crack recognition frame. Specifically: To enable the device to distinguish wall holes and small protrusions during measurement and avoid misjudgment of the crack area, in this embodiment, the image acquisition unit 3 is arranged above the width measurement unit 4 to collect images of the crack area. Since the width measurement unit 4 is in direct contact with the wall, it is impossible to observe the position where the crack is distributed through the image acquisition unit 3. At this time, the position of the crack can be estimated through the image acquisition unit 3 above the width measurement unit 4; that is, the crack image above the width measurement unit 4 is captured by the image acquisition unit 3, and the lightweight neural network built into the processing chip of the second circuit board 23 is used to detect the crack in the crack image. The lightweight crack detection neural network includes, but is not limited to, existing neural networks such as lightM-Unet. Thus, the crack position information is obtained, mainly including the abscissa x of the lower end position of the crack crack and the width d of the crack recognition frame.

[0089] Then, after obtaining the crack position information above the width measurement unit 4, a crack distribution probability function is established through known information to estimate the crack distribution in the area of the width measurement unit 4. The crack distribution probability function represents the probability of cracks appearing at different positions in the area of the width measurement unit. The higher the function value, the greater the probability of cracks appearing in this area. The crack distribution probability function established in the form of a Gaussian function is:

[0090]

[0091] where μ = x crack , σ = kd, and k is determined by the image size and brightness curve sampling rate collected by the camera.

[0092] Furthermore, after inferring the probability of the crack appearance position, it is also necessary to jointly analyze and process the focus brightness curve in the focus state and the crack distribution probability function, thereby proposing a crack width measurement algorithm. First, after normalizing the focus brightness curve, its complementary curve is multiplied by the crack distribution probability function to obtain the processed curve L p (x) = (1 - Normal(L(x))) · g(x), and the position x corresponding to the minimum value of the processed curve L p (x) is the true crack position x real ; finally, the average value of the focus brightness curve is obtained For the true crack position x of the focus brightness curve L(x) real Calculate the number of pixel points num at both ends lower than the average value , and multiply the obtained number of pixel points num by the pixel width φ to obtain the crack width width = num · φ.

[0093] The crack width measurement algorithm highlights the curve features of the positions with a high probability of crack distribution, weakens the curve features of other areas, and avoids misjudgment of the crack area caused by pits and protrusions in other areas.

[0094] At the same time, in order to improve the accuracy of crack width measurement, the crack width measurement algorithm is used to process two rows of rod lens modules 8, and a set of crack width data is obtained for each row. Finally, the crack width is taken as the average of the two.

[0095] When measuring the crack width, the device using the CIS linear image sensor principle to measure cracks is easily affected by uneven and undulating walls, resulting in out-of-focus imaging and errors. Moreover, this kind of device cannot distinguish between wall pits and small protrusions, which is likely to cause misjudgment of the crack area. The micro-camera device using the probe imaging to measure cracks has a small measurement range, and the probe needs to be accurately placed on the crack during use, with low working efficiency. Therefore, it is necessary to solve this problem by adopting the above technical solution, which mainly includes the scanning gun housing 1 and the scanning head panel 2. An image acquisition unit 3 and a width measurement unit 4 for measuring the crack width are installed on the scanning head panel 2.

[0096] During measurement, the scanning head panel 2 is closely attached to the wall where the crack is located, so that the crack appears within the field of view of the image acquisition unit 3, and the crack direction is preferably perpendicular to the width measurement unit 4. During this process, the two rows of rod lens modules 8 of the width measurement unit can retract backward relative to the scanning head panel 2, so that the measurement can adapt to the uneven crack wall. The rod lens module 8 retracts more in the protruding area of the wall and less in the sunken area of the wall. Through this telescopic mechanism, each rod lens array 11 is kept in focus with the wall. Then, the micro stepping motor 20 is used to control the front and back movement of the photosensitive chip 9. During this process, the crack brightness curve when the rod lens array 11 is in focus with the photosensitive chip 9 is obtained through the focus brightness curve selection algorithm. Then, the crack image is obtained from the image acquisition unit 3, the crack position is obtained through the built-in crack detection algorithm, and the position of the crack within the rod lens module is further deduced. Finally, the brightness curve data of the rod lens module at this specific position is processed and analyzed to obtain the crack width data.

[0097] Embodiment 2

[0098] This embodiment provides a measurement method for a portable crack width measurement device for non-flat walls, including the following steps:

[0099] Step 1: Move the device above the surface of the crack to be measured through the handle 27, and keep the two rows of rod lens modules 8 as perpendicular as possible to the crack direction.

[0100] Step 2: Press the scanning head panel 2 against the surface of the crack to be measured, so that the scanning head panel 2 is in close contact with the crack surface. Compress the spring through the baffle, and the reset rod 15 expands and contracts accordingly, driving each rod lens array to expand and contract independently, so that the light-transmitting glass contacts the wall surface, thereby enabling the rod lens module 8 to adapt to the undulating wall surface.

[0101] Step 3: Press the measurement button 25, and the image acquisition unit 3 takes an image of the crack within the shooting area. The micro stepping motor 20 controls the photosensitive chip 9 to collect the crack brightness curves at different focal lengths.

[0102] Step 4: The chip inside the second circuit board 23 calls the focusing brightness curve selection algorithm to select the focusing brightness curves of each rod lens module 8, realizes the brightness self-compensation between the focusing brightness curves through the brightness curve self-compensation algorithm and merges and splices the focusing brightness curves, calls the crack detection algorithm to identify the crack positions in the crack image, and finally calls the crack width measurement algorithm to measure the crack width, and displays the final crack width result, the crack image, and the two groups of focusing brightness curves on the display screen 26.

[0103] Although the specific implementation manners of the present invention are described above in conjunction with the accompanying drawings, it is not a limitation to the protection scope of the present invention. Those skilled in the art should understand that based on the technical solutions of the present invention, various modifications or deformations that can be made by those skilled in the art without creative efforts are still within the protection scope of the present invention.

Claims

1. A portable crack width measuring device for non-flat walls, characterized in that: Comprising: a housing, an image acquisition unit, a width measurement unit, and a processing unit provided on the housing; the image acquisition unit is configured to acquire a crack image; the width measurement unit includes at least two rows of rod lens modules with at least two rod lens modules arranged side by side in the same direction in each row, a photosensitive module and a moving mechanism located directly behind the rod lens modules; each rod lens module includes a rod lens array, a module fixing mechanism provided on the housing, a telescopic mechanism provided inside the module fixing mechanism and connected to the rod lens array, and a light-transmitting glass provided on the rod lens array, so as to drive the movement of the rod lens array through the telescopic mechanism, thereby bringing the light-transmitting glass into contact with the wall surface; the moving mechanism includes structural members provided at both ends of the photosensitive module, a slide rail for carrying the structural members, and a motor for controlling the movement of the structural members on the slide rail, so as to drive the photosensitive module to acquire crack brightness curves at different focal lengths; the processing unit receives the crack image and the crack brightness curve, and is configured to identify the crack position information according to the crack image, select the focus brightness curves of all the rod lens modules from the crack brightness curve, perform brightness self-compensation and merging on the focus brightness curves, and then calculate the crack width in combination with the crack position information.

2. A portable crack width measuring device for a non-flat wall surface as claimed in claim 1, characterized in that: A reserved groove is provided inside the module fixing mechanism, the telescopic mechanism is provided in the reserved groove, the telescopic mechanism includes a spring, a reset rod, and a baffle. The reset rod passes through the spring and is provided in the reserved groove. The baffle is provided on the top of the rod lens array, and the baffle is pressed by the reset rod against the inner wall of the reserved groove. By compressing the spring with the baffle, each rod lens array can be telescopically moved independently, so that the light-transmitting glass is in contact with the wall surface.

3. A portable crack width measurement device for a non-flat wall surface according to claim 1, wherein the thickness of the light-transmitting glass is set to the focal length of the rod lens array; the two rows of rod lens modules face the same direction, the lower row of rod lens modules is in an inverted state, the rod lens arrays in the two rows of rod lens modules are in contact with each other, and the two rows of rod lens modules are arranged in a "pin" shape with a dislocation.

4. A portable crack width measuring device for a non-flat wall surface as claimed in claim 1, characterized in that: the photosensitive module includes at least two photosensitive chips and a first circuit board. The at least two photosensitive chips are arranged in parallel on the first circuit board, and the rod lens array of one row of rod lens modules corresponds to one photosensitive chip.

5. A portable crack width measuring device for non-flat wall surface as claimed in claim 1, characterized in that: the housing includes a scanner gun housing and a scanner head panel. The scanner head panel is installed at the head of the scanner gun housing. The image acquisition unit and the width measurement unit are installed on the scanner head panel, and the light-transmitting glass protrudes from the scanner head panel.

6. A portable crack width measuring device for a non-flat wall surface as claimed in claim 1, characterized in that: The process of selecting the focus brightness curve includes: intercepting the crack brightness curves of each rod lens module at different focal lengths, respectively calculating the first derivative array and the corresponding derivative standard deviation; and selecting the group of crack brightness curves with the largest standard deviation as the focus brightness curve of the current rod lens module.

7. A portable crack width measuring device for a non-flat wall surface as claimed in claim 1, characterized in that: The process of brightness self-compensation and merging includes: standardizing the focus brightness curve to obtain a standardized brightness curve with a mean of zero, splicing the standardized brightness curves in rows, and splicing the missing standardized brightness curves formed at the junction of adjacent rod lens modules using another row of standardized brightness curves at the same position, and introducing an offset coefficient during splicing so that the starting point of the standardized brightness curve at the missing part coincides with the ending point of the previous standardized brightness curve, thereby forming at least two complete focus brightness curves.

8. A portable crack width measuring device for a non-flat wall surface as claimed in claim 1, characterized in that: The process of calculating the crack width in combination with the crack location information includes: The crack position information includes the horizontal coordinate of the lower end of the crack and the width of the crack identification frame. Based on this, a crack distribution probability function is established. The focus brightness curve is normalized and its complementary curve is multiplied by the crack distribution probability function to obtain a processed curve. The position corresponding to the minimum value of the processed curve is the real crack position. The average value of the focus brightness curve is obtained, and the number of pixels below the average value at the left and right ends of the actual crack position of the focus brightness curve is calculated. The crack width is obtained by multiplying the obtained number of pixels by the pixel width.

9. A portable crack width measuring device for a non-flat wall surface as claimed in claim 8, characterized in that: A group of crack widths is obtained based on the focus brightness curve of each row of rod lens modules, and the final crack width is the average value of the crack widths of each group.

10. A method for measuring a portable crack width measuring device for a non-flat wall surface according to any one of claims 1 to 9, characterized in that: include: Move the portable crack width measuring device above the crack surface to be measured, keeping the rod lens module perpendicular to the crack direction; The scanning head panel is pressed toward the crack surface to be detected, so as to compress the spring through the baffle plate, and drive each rod lens array to move independently, so that the light-transmitting glass contacts the wall surface; The crack image is adopted by the image acquisition unit, and the crack brightness curve under different focal lengths is acquired by driving the photosensitive module; The crack position information is identified according to the crack image, the focus brightness curves of all rod lens modules are selected from the crack brightness curves, the focus brightness curves are self-compensated for brightness and merged, and the crack width is calculated in combination with the crack position information.

Images