A method for marking corrosion defects based on laser projection

Abstract

The present application relates to the field of corrosion detection, and particularly relates to a corrosion defect marking method based on laser projection. The method is as follows: array laser defect marking instrument and infrared laser imaging detector are fixedly arranged on the same side of the detected structure; a positioning module is arranged on the detected structure, and one set of positioning module is arranged in each of the array laser defect marking instrument and the infrared laser imaging detector; a space reference coordinate system is constructed by the positioning module; all the positioning modules are mutually calibrated; the infrared laser imaging detector is used to detect the defect position, and the coordinates of the defect position on the imaging plane are converted into the coordinates under the space reference coordinate system; the positioning module in the infrared laser imaging detector transmits the coordinates P of the defect position to the array laser defect marking instrument, and the array laser defect marking instrument converts the coordinates of the defect position under the space reference coordinate system into the emission angle under its own coordinate system, so that the light spot is accurately projected to the defect position. The present application can mark the defect position in real time.

Description

Technical Field

[0001] This invention relates to the field of corrosion detection, and in particular to a method for marking corrosion defects based on laser projection. Background Technology

[0002] In the maintenance of modern industrial facilities, the integrity of the anti-corrosion coating directly affects the equipment's lifespan and operational safety. Laser infrared non-destructive testing (LDPT), as an advanced detection method, heats the anti-corrosion coating through active infrared radiation and records the heat conduction process using an infrared camera, thereby identifying defects such as peeling, insufficient thickness, water seepage, or bubbles. Due to its non-contact and high-efficiency characteristics, this technology is widely used in corrosion monitoring of critical facilities such as oil pipelines, chemical storage tanks, ship structures, and large steel structures. However, although infrared imaging systems can accurately capture the thermal anomaly signals of defects and generate visualized infrared images, a key bottleneck exists: it cannot automatically and in real-time mark the actual physical location of defects on-site. Secondary manual positioning and marking are still required, severely limiting detection efficiency and accuracy.

[0003] In practice, inspectors first acquire sequential thermal images of the surface being tested using an infrared thermal imager, and then use software to analyze and identify abnormal areas. These abnormalities are typically presented as areas of different colors or brightness on the image, indicating potential corrosion or coating failure. However, infrared images themselves are only two-dimensional temperature field data and cannot be directly mapped to the specific coordinates of the actual structure. Therefore, staff must analyze the photos after taking them, and then bring measuring tools (such as tape measures, laser rangefinders, etc.) to the site to manually verify and mark the approximate location of the defects estimated from the images, often using paint pens, stickers, or markers to make the markings on-site. This process is not only time-consuming and labor-intensive, but also highly susceptible to incomplete defect handling due to positioning errors, omissions, or mismarking. Especially in the inspection of large structures (such as long-distance pipelines or large storage tanks), the positioning error of manual marking may be further amplified, ultimately affecting the quality of repair.

[0004] Furthermore, this problem is not unique to infrared detection technology. Other widely used non-destructive testing methods, such as ultrasonic testing, eddy current testing, and microwave testing, although differing in their detection principles and data formats, mostly lack the ability to couple with the physical space in real time for calibration. They may be able to efficiently diagnose the presence of defects and even assess their size and severity, but almost none of them can accurately mark their spatial location on-site simultaneously. This step-by-step operation mode of "detection-analysis-relocation" has become a key obstacle restricting further improvements in the response speed and automation level of such technologies.

[0005] Therefore, developing a technology that can mark the location of corrosion defects in real time and automatically has become an urgent need in the field of industrial non-destructive testing. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a corrosion defect marking method based on laser projection, which can mark the defect location in real time.

[0007] This invention provides a method for marking corrosion defects based on laser projection, comprising the following steps:

[0008] Step S1: Fix the array laser defect marker and the infrared laser imaging detector on the same side of the structure being inspected;

[0009] Step S2: Arrange at least 3 sets of positioning modules on the structure to be inspected, with 1 set of positioning modules arranged in each of the array laser defect marker and the infrared laser imaging detector; construct a spatial reference coordinate system using the positioning modules; and calibrate all positioning modules against each other.

[0010] Step S3: Use an infrared laser imaging detector to detect the defect location, and convert the coordinates of the defect location on the imaging plane into coordinates P(x,y,z) in the spatial reference coordinate system;

[0011] Step S4: The positioning module in the infrared laser imaging detector transmits the coordinates P of the defect location to the array laser defect marker. The array laser defect marker converts the defect location coordinates in the spatial reference coordinate system into the emission angle in its own coordinate system, so that the light spot is accurately projected onto the defect location.

[0012] In one specific embodiment of the present invention, the three sets of positioning modules arranged on the detected structure are distributed in a triangular pattern.

[0013] In a specific embodiment of the present invention, step 2 specifically comprises:

[0014] Step S2-1: Construct a spatial reference coordinate system using all positioning modules;

[0015] Step S2-2: The positioning modules measure the distance between each other and use the trilateration method to calculate their respective coordinates in the spatial reference coordinate system;

[0016]

[0017] d ij Δt is the distance between two points. ij denoted as , where is the total time from when one positioning module transmits a signal to when another positioning module transmits a signal back; c is the speed of electromagnetic waves.

[0018] In one specific embodiment of the present invention, the spatial reference coordinate system is established using an infrared laser imaging detector as the reference point, a GPS signal as the reference point, or an internal signal reference point of a nuclear power plant as the origin of the coordinate system.

[0019] In a specific embodiment of the present invention, in step 2: an infrared laser imaging detector is used as the reference origin, the line connecting the array laser defect marker and the infrared laser imaging detector is the X-axis, the plane where any set of positioning modules on the inspected structure and the infrared laser imaging detector are located is the XY plane, and the direction perpendicular to the XY plane is the Z-axis direction, thus establishing a coordinate system.

[0020] In a specific embodiment of the present invention, in step 3, the pixel coordinates of the defect location in the imaging plane of the infrared laser imaging detector are (u,v), and the center of the imaging plane is the pixel origin (u0,v0).

[0021] The offset of the defect location in the imaging plane: Δu = u - u0, Δv = v - v0;

[0022] The coordinates of the defect location in the spatial reference coordinate system are P(x,y,z);

[0023]

[0024] z: Distance from the defect to the infrared detector lens; f: Focal length of the infrared detector lens;

[0025] k u k is the x-axis imaging conversion coefficient. v y is the y-axis imaging conversion coefficient.

[0026] In a specific embodiment of the present invention, in step 4, the launch angle includes azimuth angle α and elevation angle β;

[0027] The azimuth angle α is the angle between the laser in the XY plane and the Y axis;

[0028] The pitch angle β is the angle between the laser beam in the XY plane and the Z axis;

[0029] The laser array is controlled to adjust the emission direction according to the emission angle, so that the light plate is accurately projected onto the defect location.

[0030] In one specific embodiment of the present invention, it further includes:

[0031] The infrared laser imaging detector sends defect information to the array laser defect marker. The array laser defect marker selects different colored laser beams according to the defect and, combined with the emission angle, precisely projects the light spot onto the defect location.

[0032] The present invention also provides a corrosion defect marking system based on laser projection, comprising:

[0033] Infrared laser imaging detector, array laser defect marker;

[0034] Each of the array laser defect marker and the infrared laser imaging detector is equipped with a positioning module;

[0035] At least three positioning modules are deployed on the structure being inspected;

[0036] The software and communication unit is used for data communication between the infrared laser imaging detector, the array laser defect marker, and multiple positioning modules.

[0037] In one specific embodiment of the present invention, the communication method is wired communication or wireless communication.

[0038] Compared with the prior art, the laser projection-based corrosion defect marking method of the present invention has the following advantages:

[0039] (1) When the present invention is combined with a fixed online non-destructive corrosion detection equipment to perform non-contact remote online detection or monitoring of structures, it can quickly and efficiently realize the location marking of defects, the delineation of shape areas, and the color marking of defect types; for example, the present invention can mark multiple defects simultaneously with laser beams of different colors, and the degree of defects can be displayed by color marking.

[0040] (2) This invention is a remote visible light projection mark, which can be widely used in various remote non-contact non-destructive anti-corrosion layer detection scenarios, especially in some inaccessible areas and high-risk areas, and has very positive application value.

[0041] (3) This invention can be applied to online monitoring and can operate continuously online. When used with online corrosion monitoring equipment, it can quickly and timely project the type and location of defects, providing important assistance to on-site maintenance personnel in making rapid decisions and solving problems;

[0042] (4) When the positioning module, defect detector, etc. are transformed into mobile inspection mode such as robot or drone, the present invention is also applicable and has high scalability. Attached Figure Description

[0043] Figure 1 A schematic diagram showing the structure of a corrosion defect marking system based on laser projection;

[0044] In the figure, 1-Array laser defect marker; 2-Infrared laser imaging detector; 2.1-Active infrared heating lamp; 2.2-Infrared camera; 3-Positioning module; 3.1-Positioning module A; 3.2-Positioning module B; 3.3-Positioning module C; 4-Software and communication unit; 5-Structure under inspection; 6-Laser beam; 7-Infrared laser beam. Detailed Implementation

[0045] To further understand the present invention, embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the present invention.

[0046] An embodiment of the present invention discloses a method for marking corrosion defects based on laser projection, comprising the following steps:

[0047] Step S1: Fix the array laser defect marker and the infrared laser imaging detector on the same side of the structure being inspected;

[0048] The array laser defect marker is fixed in position and does not move.

[0049] The array laser defect marker can simultaneously emit laser beams of multiple colors and can also form light spot projections of different shapes at a distance. Therefore, it can be used to mark multiple defects simultaneously.

[0050] The infrared laser imaging detector is fixed in position and can remotely and non-destructively inspect large areas for corrosion defects.

[0051] Step S2: Arrange at least 3 sets of positioning modules on the structure to be inspected, with 1 set of positioning modules arranged in each of the array laser defect marker and the infrared laser imaging detector; construct a spatial reference coordinate system using the positioning modules; and calibrate all positioning modules against each other.

[0052] The positioning module arranged on the structure being inspected is attached to the surface of the structure being inspected and is used to determine the spatial information of the structure being inspected.

[0053] The number of positioning modules arranged on the structure being inspected is not limited to three sets. The more modules there are, the more detailed the spatial shape information of the object being inspected will be.

[0054] If three sets are selected, preferably, the three sets of positioning modules are arranged in a triangular pattern.

[0055] Step 2 specifically involves:

[0056] Step S2-1: Construct a spatial reference coordinate system using all positioning modules;

[0057] The spatial reference coordinate system is established using an infrared laser imaging detector as the reference point, a GPS signal, or an internal signal reference point of a nuclear power plant as the origin.

[0058] Preferably, a coordinate system is established with the infrared laser imaging detector as the reference origin, the line connecting the array laser defect marker and the infrared laser imaging detector as the X-axis, the plane between any set of positioning modules on the inspected structure and the infrared laser imaging detector as the XY plane, and the direction perpendicular to the XY plane as the Z-axis direction.

[0059] Step S2-2: The positioning modules measure the distance between each other and use the trilateration method to calculate their respective coordinates in the spatial reference coordinate system.

[0060] The distance measurement formula is:

[0061] d ij Δt is the distance between two points. ij is the total time from when one positioning module transmits a signal to when another positioning module transmits a signal back, in seconds; c is the speed of electromagnetic waves.

[0062] Step S3: Use an infrared laser imaging detector to detect the defect location, and convert the coordinates of the defect location on the imaging plane into coordinates P(x,y,z) in the spatial reference coordinate system;

[0063] In the imaging plane of the infrared laser imaging detector, the pixel coordinates of the defect location are (u, v), and the center of the imaging plane is the pixel origin (u0, v0). The pixel origin is a known parameter of the device. For example, if the image resolution of the infrared laser imaging detector is 1920×1080, then u0=960, v0=540.

[0064] The offset of the defect location in the imaging plane: Δu = u - u0, Δv = v - v0;

[0065] The coordinates of the defect location in the spatial reference coordinate system are P(x,y,z);

[0066]

[0067] z: Distance from the defect to the infrared detector lens, in meters, measured by the positioning module or calculated from the known thickness of the structure; f: Focal length of the infrared detector lens, in meters, a known equipment parameter;

[0068] k u k is the x-axis imaging conversion coefficient. v These are the y-axis imaging conversion coefficients; these two coefficients depend on the parameters and size of the imaging lens and are known device parameters.

[0069] Step S4: The positioning module in the infrared laser imaging detector transmits the coordinates P of the defect location to the array laser defect marker. The array laser defect marker converts the defect location coordinates in the spatial reference coordinate system into the emission angle in its own coordinate system, so that the light spot is accurately projected onto the defect location.

[0070] The launch angle includes the azimuth angle α and the elevation angle β;

[0071] The azimuth angle α is the angle between the laser in the XY plane and the Y axis;

[0072] The pitch angle β is the angle between the laser beam in the XY plane and the Z axis;

[0073] The laser array is controlled to adjust the emission direction according to the emission angle, so that the light plate is accurately projected onto the defect location.

[0074] Also includes:

[0075] The infrared laser imaging detector sends defect information to the array laser defect marker. The array laser defect marker selects different colored laser beams according to the defect and, combined with the emission angle, precisely projects the light spot onto the defect location.

[0076] Embodiments of the present invention also disclose a corrosion defect marking system based on laser projection, such as... Figure 1 As shown, it includes:

[0077] Infrared laser imaging detector 2, array laser defect marker 1,

[0078] Each of the infrared laser imaging detector 2 and the array laser defect marker 1 is equipped with a positioning module 3, namely positioning module D and positioning module E, respectively.

[0079] The infrared laser imaging detector 2 includes an active infrared heating lamp 2.1 and an infrared camera 2.2; the active infrared heating lamp 2.1 emits an infrared laser beam 7 to monitor and detect the location of defects;

[0080] The array laser defect marker 1 can simultaneously emit laser beams 6 of multiple colors to mark the location of defects;

[0081] At least three positioning modules are arranged on the structure 5 being inspected, namely positioning module A3.1, positioning module B3.2, and positioning module C3.3.

[0082] The software and communication unit 4 is used for data communication between the infrared laser imaging detector 1, the array laser defect marker 2, and multiple positioning modules 3.

[0083] The communication method is either wired or wireless.

[0084] Example 1

[0085] A method for marking corrosion defects based on laser projection includes the following steps:

[0086] Step S1: Fix the array laser defect marker and the infrared laser imaging detector on the same side of the structure being inspected;

[0087] The array laser defect marker is fixed in position and does not move.

[0088] The array laser defect marker can simultaneously emit laser beams of multiple colors and can also form light spot projections of different shapes at a distance. Therefore, it can be used to mark multiple defects simultaneously.

[0089] The infrared laser imaging detector is fixed in position and can remotely and non-destructively inspect large areas for corrosion defects.

[0090] Step S2: Arrange three sets of positioning modules in a triangular distribution on the structure to be inspected, namely positioning module A3.1, positioning module B3.2, and positioning module C3.3;

[0091] Each of the infrared laser imaging detector 2 and the array laser defect marker 1 is equipped with a positioning module, namely positioning module D and positioning module E, respectively.

[0092] Construct a spatial reference coordinate system using all positioning modules;

[0093] A coordinate system is established with the infrared laser imaging detector as the reference origin, the line connecting positioning module D and positioning module E as the X-axis, the plane containing positioning module A and positioning module D as the XY plane, and the direction perpendicular to the XY plane as the Z-axis direction.

[0094] The positioning modules measure distances in pairs and use trilateration to calculate their respective coordinates in the spatial reference coordinate system.

[0095] The distance measurement formula is:

[0096] d ij Δt is the distance between two points. ij is the total time from when one positioning module transmits a signal to when another positioning module transmits a signal back, in seconds; c is the speed of electromagnetic waves.

[0097] A spatial reference coordinate system is constructed by the positioning module; all positioning modules are calibrated against each other.

[0098] Step S3: Use an infrared laser imaging detector to detect the defect location, and convert the coordinates of the defect location on the imaging plane into coordinates P(x,y,z) in the spatial reference coordinate system;

[0099] In the imaging plane of the infrared laser imaging detector, the pixel coordinates of the defect location are (u, v), and the center of the imaging plane is the pixel origin (u0, v0). The pixel origin is a known parameter of the device. For example, if the image resolution of the infrared laser imaging detector is 1920×1080, then u0=960, v0=540.

[0100] The offset of the defect location in the imaging plane: Δu = u - u0, Δv = v - v0;

[0101] The coordinates of the defect location in the spatial reference coordinate system are P(x,y,z);

[0102]

[0103] z: Distance from the defect to the infrared detector lens, in meters, measured by the positioning module or calculated from the known thickness of the structure; f: Focal length of the infrared detector lens, in meters, a known equipment parameter;

[0104] k u k is the x-axis imaging conversion coefficient. v These are the y-axis imaging conversion coefficients; these two coefficients depend on the parameters and size of the imaging lens and are known device parameters.

[0105] Step S4: The positioning module inside the infrared laser imaging detector transmits the coordinates P of the defect location and the defect information to the array laser defect marker.

[0106] The array laser defect marker converts the defect location coordinates in the spatial reference coordinate system into the emission angle in its own coordinate system, wherein the emission angle includes the azimuth angle α and the elevation angle β.

[0107] The azimuth angle α is the angle between the laser beam in the △ADE plane and the Y-axis;

[0108] The pitch angle β is the angle between the laser beam in the △ADE plane and the Z-axis;

[0109] The array laser defect marker selects different colored laser beams according to the defect condition and, combined with the emission angle, precisely projects the light spot onto the defect location. It controls the laser array to adjust the emission direction according to the emission angle, so that the light plate is precisely projected onto the defect location.

[0110] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0111] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for marking corrosion defects based on laser projection, characterized in that, The method comprises the following steps: Step S1: fixing and arranging the array laser defect marking instrument and the infrared laser imaging detector on the same side of the detected structure; Step S2: arranging at least three sets of positioning modules on the detected structure, one set of positioning module is arranged in the array laser defect marking instrument and the infrared laser imaging detector; a space reference coordinate system is constructed by the positioning modules; all the positioning modules are mutually calibrated; Step S3: detecting the defect position by the infrared laser imaging detector, and converting the coordinates of the defect position in the imaging plane into the coordinates P(x, y, z) in the space reference coordinate system; In the imaging plane of the infrared laser imaging detector, the pixel coordinates of the defect position are (u, v), and the center of the imaging plane is the pixel origin (u0, v0); The offset of the defect position in the imaging plane: Δu = u-u0, Δv = v-v0; The coordinates P(x, y, z) of the defect position in the space reference coordinate system; Z: the distance from the defect to the lens of the infrared detector; f: the focal length of the lens of the infrared detector; k u is the x-axis imaging conversion coefficient, k v is the y-axis imaging conversion coefficient; Step S4: the positioning module in the infrared laser imaging detector transmits the coordinates P of the defect position to the array laser defect marking instrument, and the array laser defect marking instrument converts the coordinates of the defect position in the space reference coordinate system into the emission angle in its own coordinate system, so that the light spot is accurately projected to the defect position.

2. The method of claim 1, wherein the method further comprises: The three sets of positioning modules arranged on the detected structure are in a triangular distribution.

3. The method of claim 2, wherein the laser projection-based corrosion defect marking method is characterized by, The step S2 is specifically: Step S2-1: constructing the space reference coordinate system by all the positioning modules; Step S2-2: measuring the distance between the positioning modules two by two, and calculating the coordinates of each in the space reference coordinate system by the three-edge measurement method; d ij is the distance between two points; Δt ij is the total time for a signal to be transmitted from one localization module to another and back; c is the speed of electromagnetic waves.

4. The method of claim 3, wherein the laser projection-based corrosion defect marking method is characterized by, The space reference coordinate system is established with the infrared laser imaging detector as the reference point, the GPS signal or the internal signal reference point of the nuclear power plant as the coordinate origin.

5. The method of claim 4, wherein the laser projection-based corrosion defect marking method is characterized by, In the step S2, the infrared laser imaging detector is taken as the reference origin, the line connecting the array laser defect marking instrument and the infrared laser imaging detector is taken as the X-axis, the plane where any one set of positioning module on the detected structure and the infrared laser imaging detector are located is taken as the X-Y plane, and the direction perpendicular to the X-Y plane is taken as the Z-axis direction, so as to establish the coordinate system.

6. The method of claim 1, wherein the method further comprises: In the step S4, the emission angle includes the azimuth angle α and the elevation angle β; The azimuth angle α is the included angle between the laser and the Y-axis in the X-Y plane; The elevation angle β is the included angle between the laser and the Z-axis in the X-Y plane; The laser array adjusts the emission direction according to the emission angle, so that the light spot is accurately projected to the defect position.

7. The method of claim 1, wherein the method further comprises: Further comprising: The infrared laser imaging detector sends the defect information to the array laser defect marking instrument, the array laser defect marking instrument selects the laser beam of different colors according to the defect condition, and combines the emission angle to accurately project the light spot to the defect position.

8. A laser projection based corrosion defect marking system characterized in that, Comprise: The infrared laser imaging detector and the array laser defect marking instrument; One set of positioning module is arranged in the array laser defect marking instrument and the infrared laser imaging detector; At least three sets of positioning modules are arranged on the detected structure; The software and communication unit is used for data communication among the infrared laser imaging detector, the array laser defect marking instrument and the multiple positioning modules; The positioning modules construct a space reference coordinate system; all the positioning modules calibrate each other; The infrared laser imaging detector detects the defect position, and converts the coordinates of the defect position on the imaging plane into coordinates P(x, y, z) under the space reference coordinate system; In the imaging plane of the infrared laser imaging detector, the pixel coordinates of the defect position are (u, v), and the center of the imaging plane is the pixel origin (u0, v0); The offset of the defect position on the imaging plane: Δu = u - u0, Δv = v - v0; The coordinates P(x, y, z) of the defect position under the space reference coordinate system; z: the distance from the defect to the lens of the infrared detector; f: the focal length of the lens of the infrared detector; k u is the x-axis imaging conversion coefficient, k v is the y-axis imaging conversion coefficient.

9. The laser projection based corrosion defect marking system as claimed in claim 8, wherein, The data communication mode between the plurality of positioning modules is wired communication or wireless communication.

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