CN113720573B - Wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement - Google Patents
Wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement Download PDFInfo
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- CN113720573B CN113720573B CN202111005397.XA CN202111005397A CN113720573B CN 113720573 B CN113720573 B CN 113720573B CN 202111005397 A CN202111005397 A CN 202111005397A CN 113720573 B CN113720573 B CN 113720573B
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Abstract
The application discloses a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, which comprises a vision temperature measurement subsystem, a temperature field image acquisition subsystem and a temperature field image acquisition subsystem, wherein the vision temperature measurement subsystem is used for acquiring a temperature field image of the surface of a wind tunnel; the optical fiber temperature measurement subsystem is used for measuring the temperature of a measurement blind area of the optical fiber temperature measurement subsystem on the surface of the wind tunnel; the temperature correction subsystem is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem; and the 3D display subsystem is used for displaying the three-dimensional temperature field and the cold leakage point position of the wind tunnel surface on the wind tunnel 3D model in real time. The application provides a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, which is used for realizing the purposes of monitoring the temperature change of the wind tunnel surface in real time and ensuring the accuracy and stability of cold leakage monitoring.
Description
Technical Field
The application relates to the field of wind tunnel tests, in particular to a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement.
Background
The wind tunnel test is to fix the model or the real object of the aircraft in the ground artificial environment according to the relativity principle of the movement, and artificially make the air flow to simulate various complex flight states in the air so as to acquire test data. In order to meet the temperature requirements of certain special tests, a heat insulation layer needs to be paved on the surface of the wind tunnel, and the temperature of the surface of the heat insulation layer is not lower than the local dew point temperature under normal conditions according to the design requirements of the heat insulation layer. The surface temperature of the cavity is reduced upon failure of the insulation. In the wind tunnel operation process, the state of the heat preservation layer needs to be monitored to judge whether the heat preservation layer fails. However, the conventional infrared temperature measurement technology has the following disadvantages: (1) The accuracy is reduced due to the influence of factors such as the difference of the distance from the wind tunnel surface, the formed observation angle and even the difference of the surface finish; (2) The wind tunnel equipment has complex field environment, the wind tunnel of the measured object has large and irregular volume, the outside of the tunnel body is provided with a ladder platform and is provided with equipment such as a measurement and control cabinet, and the ladder platform, the measurement and control cabinet and the like can shield infrared imaging. Therefore, the leakage cold monitoring of the wind tunnel surface is always a technical problem in the field.
Disclosure of Invention
The application provides a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, which is used for realizing the purposes of monitoring the temperature change of the wind tunnel surface in real time and ensuring the accuracy and stability of cold leakage monitoring.
The application is realized by the following technical scheme:
wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combination temperature measurement, comprising:
the visual temperature measurement subsystem is used for acquiring a temperature field image of the surface of the wind tunnel;
the optical fiber temperature measurement subsystem is used for measuring the temperature of a measurement blind area of the optical fiber temperature measurement subsystem on the surface of the wind tunnel;
the temperature correction subsystem is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem;
and the 3D display subsystem is used for displaying the three-dimensional temperature field and the cold leakage point position of the wind tunnel surface on the wind tunnel 3D model in real time.
Aiming at the problems of wind tunnel surface cold leakage monitoring in the prior art, the application provides a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement.
The application adopts the combination of vision and optical fiber temperature measurement and positioning technology to monitor the surface temperature change of the hole body. And mapping the monitoring result directly to the surface of the wind tunnel 3D model, displaying an abnormal area in a warning way, and giving the number of the heat insulation block at the position of the leakage point. The method ensures seamless, missing-free and error-free cold leakage monitoring, reduces redundancy of the system and reduces waste of system computing resources. The temperature correction subsystem is used for correcting and evaluating the temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem so as to ensure accurate temperature measurement and ensure that the temperature measurement data of all the subsystems are consistent.
Further, the visual temperature measurement subsystem is also used for acquiring a texture image of the surface of the hole. Texture images on the surface of the cavity body can be realized through a visible light image acquisition technology, and the appearance change (such as frost, icing and the like) of the cavity body caused by cold leakage can be detected and identified through an image identification technology, so that the visual temperature measurement subsystem can provide a secondary judging function. Preferably, the cold leakage monitoring process of the visual temperature measurement subsystem can be monitored through a deep learning algorithm so as to improve the self-adaptive capacity of the visual temperature measurement subsystem.
Further, the visual temperature measurement subsystem comprises a plurality of groups of double-light cameras which are arranged outside the wind tunnel in a pairwise manner; the double light of the double-light camera is infrared light and visible light;
each double-light camera is provided with an effective temperature measuring area for infrared temperature measurement of the surface of the wind tunnel, and the effective temperature measuring areas of the two opposite double-light cameras in each group are partially overlapped;
the installation height of all the double-light cameras is higher than the top of the wind tunnel, and the measuring area of the visual temperature measuring subsystem at least covers the upper surface of the wind tunnel.
The double-light cameras in the visual temperature measurement subsystem are installed by taking groups as units, each group comprises two double-light cameras which are relatively distributed outside the wind tunnel, double light of each double-light camera is infrared light and visible light, infrared temperature measurement on the surface of the hole body is realized through the infrared light, and a texture image on the surface of the hole body is obtained through the visible light. In addition, aiming at the problem that the precision of infrared temperature measurement is affected by factors such as different smoothness of the surface of an object to be measured and the observation angle formed by the object to be measured, the application can also carry out infrared temperature measurement tests with different smoothness and angles on the selected cameras when arranging specific installation positions of the double-light cameras, thereby obtaining the optimal observation distance and angle of each double-light camera and providing basis for field installation. For the reflux wind tunnel, how to reasonably monitor the outer surface of the outer side of the near tunnel (close to the wall) and the inner surface of the far tunnel (not close to the wall) by using the dual-light camera is also needed to be considered, so that the selection of the installation position of the camera is performed according to the requirements. In order to achieve the optimal monitoring effect, the two double-light cameras in each group are mutually matched, a certain common view field exists between the two double-light cameras, so that the visible surface of the pipeline is covered as large as possible, the effective measurement areas of the cameras on the two opposite sides are opposite, the size of the overlapped area is adaptively set according to actual conditions, and the size of the overlapped area is preferably about 0.5m along the circumferential direction of the hole body.
In the scheme, the installation height of all the double-light cameras is higher than the top of the wind tunnel, so that the double-light cameras monitor the surface of the wind tunnel from top to bottom, and the effective temperature measuring areas of all the double-light cameras are overlapped, so that the requirement of at least covering the outer surface of the upper half part of the wind tunnel is met.
Further, the effective temperature measurement area is obtained through measurement and calculation based on Johnson criteria; each dual-light camera has a matched pan-tilt. After the installation positions of the two-light cameras are determined according to the transfer size and shape and the corresponding factory building conditions, the effective temperature measurement area of each two-light camera is measured and calculated based on Johnson criteria. Wherein the Johnson criterion considers the recognizable standard and the recognizable standard, and the measurement result is used as a system layout scheme. Each double-light camera is provided with a matched cradle head, and cruising observation of each double-light camera can be realized through a pre-cradle head rotating path; particularly, for the infrared/visible light double-light camera, the resolution of the visible light lens is larger, the measuring range is smaller, and the resolution of the infrared lens is smaller, the measuring range is larger, and the measuring distance is longer, so that the double-light camera can only measure a small range and cannot exert the advantage of infrared temperature measurement when shooting once.
Further, the optical fiber temperature measurement subsystem comprises a temperature measurement optical fiber which is circularly paved at the lower part of the wind tunnel, and the temperature measurement optical fiber covers a measurement blind area of the visual temperature measurement subsystem on the surface of the wind tunnel; and the top end convolution part of the temperature measuring optical fiber enters the effective temperature measuring area. Besides the temperature measurement optical fiber can accurately monitor the temperature, the accurate positioning of the position can be realized through the return time of the optical fiber signal, and the calibration of the length and the temperature measurement distance on the temperature measurement optical fiber can be easily realized, so that the calibration and the correlation of the cold leakage position of the wind tunnel model are realized. In the scheme, a temperature measuring optical fiber is circularly paved at the lower part of the wind tunnel so as to fully cover the area which cannot be monitored by the visual temperature measuring subsystem; of course, the measurement blind area of the vision temperature measurement subsystem on the surface of the wind tunnel is covered by the temperature measurement optical fiber in the scheme, and besides the lower part of the wind tunnel, the measurement blind area also comprises areas for shielding infrared temperature measurement vision, such as a ladder, a platform, a measurement and control cabinet and the like, which are arranged outside the wind tunnel, and effective blind compensation measurement is realized in the areas through the temperature measurement optical fiber. Because the temperature measuring optical fiber is laid on the lower area of the wind tunnel surface in a rotary way, the rotary part is necessarily arranged at the top position of the temperature measuring optical fiber, the scheme needs to ensure that each rotary part enters the effective temperature measuring area of any double-light camera so as to ensure the effective coverage of the optical fiber, thereby improving the detection accuracy of the cold leakage area, ensuring that the detection area fully covers the whole surface of the tunnel surface and thoroughly avoiding detection blind areas.
Furthermore, a plurality of optical fiber measurement key points are distributed on the temperature measuring optical fiber at equal intervals, and redundant sections are distributed on the temperature measuring optical fiber at equal intervals. The optical fiber measurement key points can be used as optical fiber temperature measurement calibration points, so that rapid positioning of the cold leakage area is facilitated; in addition, the redundant sections are arranged on the temperature measuring optical fibers at equal intervals, namely, the redundant sections are reserved with a section of redundant length of the temperature measuring optical fibers at equal intervals, so that thermal expansion and cold contraction deformation generated by the influence of internal temperature in the wind tunnel operation process is compensated, and the influence of thermal deformation of the tunnel can be effectively overcome by the optical fiber system.
Further, the temperature correction subsystem includes:
the blackbody correction module comprises a blackbody arranged in the visual field range of the visual temperature measurement subsystem and is used for correcting the measured temperature of the visual temperature measurement subsystem;
the temperature correction evaluation module comprises a plurality of first temperature sensors arranged on the surface of the wind tunnel and a plurality of second temperature sensors arranged around the wind tunnel; the first temperature sensor is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem, and the second temperature sensor is used for monitoring the environmental temperature in the wind tunnel factory building;
the handheld thermal infrared imager is used for carrying out secondary detection on the position of the cold leakage point.
The blackbody correction module is mainly used for continuously correcting the infrared temperature measurement result in the double-light camera so as to ensure the temperature measurement precision. The blackbody is a constant temperature target, which is arranged in the field of view of the double-light camera, and the latter measures the temperature of the blackbody and performs temperature measurement calibration in real time by taking the blackbody as a reference.
The temperature correction evaluation module is mainly a first temperature sensor arranged on the surface of the wind tunnel shell, is used for carrying out online real-time monitoring on the surface temperature of the hole body and is used for correcting and evaluating the test data of the visual temperature measurement and optical fiber temperature measurement system; in addition, the method also comprises a plurality of environmental temperature sensors which are arranged around the wind tunnel, namely second temperature sensors, and when constructing a cold leakage detection algorithm, a local reference temperature is provided.
The handheld thermal infrared imager is mainly used for giving out an alarm to an abnormal area according to a monitoring result and giving out the position of a leakage point, and system maintenance personnel obtaining the information hold the handheld thermal infrared imager to the site to carry out secondary detection.
Further, the 3D display subsystem includes:
the visual temperature measurement processing module is used for processing the temperature field data acquired by the visual temperature measurement subsystem;
the optical fiber temperature measurement processing module is used for processing temperature data obtained by measurement of the optical fiber temperature measurement subsystem;
the fusion module is used for fusing the temperature data of the overlapping measurement area of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem;
the mapping module is used for mapping the fused temperature data to the wind tunnel 3D model;
and the display module is used for displaying the surface temperature field of the wind tunnel in a thermal pattern mode.
In the application, the 3D display subsystem is mainly used for displaying the result of cold leakage detection and displaying the three-dimensional temperature field and the position of the cold leakage point on the wind tunnel 3D model in real time. The 3D display subsystem adopts a data fusion technology to fuse the data of the overlapping measurement part of the visual temperature measurement and the optical fiber temperature measurement; the fusion belongs to decision-level fusion, primary conclusions are respectively obtained on the wind tunnel surface temperature information through an infrared camera and a distributed optical fiber, then decision-level fusion judgment is carried out through association processing, and finally fusion-type wind tunnel surface temperature information is obtained. And meanwhile, a data interpolation algorithm is adopted to map the fused temperature image to a wind tunnel 3D model in a fusion way, so that the surface temperature field of the wind tunnel is displayed in a heat map mode.
Further, the temperature data fusion method of the overlapping measurement area of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem comprises the following steps:
extracting optical fiber data points obtained by optical fiber temperature measurement;
and obtaining temperature data among the optical fiber data points by adopting a data interpolation algorithm, wherein a curved surface adopted by the data interpolation algorithm is obtained by fitting measurement data of a visual temperature measurement subsystem.
In the bottom area of the wind tunnel and other shielded areas, the infrared temperature measurement technology cannot shoot to obtain data, so that the temperature measurement is carried out by adopting the laid optical fiber. At the edge of the optical fiber layout, the infrared temperature measurement and the optical fiber temperature measurement have partial overlapping areas, so that data fusion is needed. The infrared temperature measurement can obtain the temperature change of continuous space, and the measurement accuracy is lower than that of an optical fiber. Optical fibers can accurately measure temperature, but fiber routing limitations result in single point data being measured by the optical fibers. In addition, the temperature resolution of the infrared temperature measurement is higher, the data mapping is smoother, and the temperature measured by the optical fiber is more accurate. Therefore, the scheme adopts the optical fiber data at the positions with the optical fiber data, and the point data is obtained by adopting an interpolation method at the points among the optical fiber data. The curved surface adopted by interpolation is obtained by fitting infrared temperature measurement data. The data of the fitted curved surface at the corresponding point of the optical fiber is the temperature measured by the optical fiber, and the change trend of the data is the same as that of the infrared temperature measurement data, namely, the data is equivalent to the trend that the optical fiber data provides accurate temperature values and the infrared temperature measurement data provides temperature change.
Further, the method for mapping the fused temperature data onto the wind tunnel 3D model is a bicubic interpolation method, which comprises the following steps:
setting the P point as the position of the target image in the (X, Y) position corresponding to the source image; the P point coordinates are P (x+u, y+v), wherein x and y respectively represent integer parts, and u and v respectively represent decimal parts;
and (3) calculating:
wherein f (x, y) is the pixel value of the P point after interpolation; x is x i ，y i Pixel coordinates in a 4 x 4 range around the P-point; i=0, 1,2,3; f (x) i ，y i ) Pixel values corresponding to pixel coordinates within a 4 x 4 range; w is an interpolation coefficient, and the value of the interpolation coefficient is as follows:
wherein a= -0.5.
According to the application, the infrared image is required to be mapped onto the wind tunnel three-dimensional model, and the number of pixel points in the wind tunnel three-dimensional model surface piece is greatly higher than the resolution of the infrared image because the resolution of the infrared image is lower, so that interpolation is required in the wind tunnel three-dimensional model surface piece to perform temperature field mapping. Meanwhile, the optical fibers arranged at the bottom of the wind tunnel are also provided with intervals, so that data interpolation is also needed when the optical fiber temperature measurement data are displayed on the model.
Formula (VI)The calculation formula is used for carrying out bicubic interpolation, and the purpose is to find out the influence factor of 16 pixel points nearest to the target image on the pixel value of the P position by finding out a coefficient, so that the pixel value of the corresponding point of the target image is obtained according to the influence factor, and the purpose of image scaling is achieved.
Formula (VI)Is the calculation of the interpolation coefficient, in the present application, W (x-x i ) When m is replaced by x-x i Calculating; calculation of W (y-y) i ) And the same is true.
According to the scheme, the mapping result with more uniform texture transition, minimum sawtooth effect and better image effect is obtained through bicubic interpolation.
Compared with the prior art, the application has the following advantages and beneficial effects:
1. the wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement adopts the combination of vision and optical fiber temperature measurement technology to monitor the surface temperature change of the tunnel. And mapping the monitoring result directly to the surface of the wind tunnel 3D model, displaying an abnormal area in a warning way, and giving the number of the heat insulation block at the position of the leakage point. The method ensures seamless, missing-free and error-free cold leakage monitoring, reduces redundancy of the system, reduces waste of calculation resources of the system, covers the surface area of the wind tunnel to be measured to the greatest extent, and has high sensitivity and response speed.
2. According to the wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, two double-light cameras in each group are matched with each other, a certain common view field exists between the two double-light cameras, and therefore the effective measurement area of the cameras on two opposite sides of the visual surface of a pipeline is covered as large as possible; and cruising of the double-light camera is realized through the cradle head, so that the camera dosage of the system can be obviously reduced, and the system layout cost is reduced.
3. The application provides a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, and provides a fusion layout scheme based on Johnson criterion and infrared test, so that the effectiveness of infrared temperature measurement is ensured.
4. The application discloses a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement, wherein optical fiber data are adopted at positions with optical fiber data, point data are obtained by adopting an interpolation method at points among the optical fiber data, and a curved surface adopted by interpolation is obtained by fitting infrared temperature measurement data; the interpolation method is bicubic interpolation, and a mapping result with more uniform texture transition, minimum sawtooth effect and better image effect can be obtained.
Drawings
The accompanying drawings, which are included to provide a further understanding of embodiments of the application and are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:
FIG. 1 is a schematic diagram of a system according to an embodiment of the present application;
FIG. 2 is a layout diagram of a dual-camera according to an embodiment of the present application;
FIG. 3 is a schematic view illustrating the installation of each group of dual-light cameras according to an embodiment of the present application;
FIG. 4 is a schematic diagram of laying a temperature measurement fiber in an embodiment of the application;
FIG. 5 is a top view of a temperature sensing fiber in an embodiment of the present application;
FIG. 6 is a simulation diagram of the fused thermometry data in an embodiment of the application;
FIG. 7 is a diagram illustrating bicubic interpolation in accordance with an embodiment of the present application;
FIG. 8 is a bicubic interpolation function diagram according to an embodiment of the application;
FIG. 9 is a schematic workflow diagram of an embodiment of the present application.
In the drawings, the reference numerals and corresponding part names:
1-wind tunnel, 2-temperature measuring optical fiber and 3-redundant segment.
Detailed Description
For the purpose of making apparent the objects, technical solutions and advantages of the present application, the present application will be further described in detail with reference to the following examples and the accompanying drawings, wherein the exemplary embodiments of the present application and the descriptions thereof are for illustrating the present application only and are not to be construed as limiting the present application. In the description of the present application, it should be understood that the terms "front", "rear", "left", "right", "upper", "lower", "vertical", "horizontal", "high", "low", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the scope of the present application.
Example 1:
in the embodiment, taking an X wind tunnel as an example, the X wind tunnel is a continuous closed backflow transonic wind tunnel driven by an axial flow compressor, and the power of the compressor is 60MW. The wind tunnel consists of a main loop of the tunnel body, an auxiliary system, a factory building and the like. The temperature range of the X wind tunnel running medium is-196 ℃ to 50 ℃, the inner layer of the tunnel body is a heat insulation layer, the outer layer of the tunnel body is a stainless steel shell, the tunnel body is insulated by the heat insulation layer, and the heat insulation layer is formed by splicing 5000 heat insulation blocks with the size of 1m multiplied by 1 m.
The surface temperature of the heat insulation layer is not lower than the local dew point temperature under normal conditions according to the design requirements of the heat insulation layer. The surface temperature of the cavity is reduced upon failure of the insulation. In the wind tunnel operation process, the state of the heat preservation layer needs to be monitored to judge whether the heat preservation layer fails. The wind tunnel currently faces the following problems in terms of temperature measurement:
(1) The distance, angle and finish of the measured object lead to the problem of reduced infrared temperature measurement precision. The infrared camera is influenced by the distance of the measured object, the formed observation angle, the surface finish and other factors due to the measurement characteristics, so that the accuracy of the infrared camera is reduced. In the project, 18 double-spectrum cameras are distributed together to cooperate with a cradle head to perform preset-position scanning type infrared temperature measurement, and when different positions of a surface finish wind tunnel are measured and determined, the temperature measurement accuracy can be affected to a certain extent due to the difference of distances and angles, so that failure of temperature measurement and cold leakage monitoring is caused.
(2) The visual equipment and the optical fiber temperature measuring equipment are reasonably deployed. Because the field environment of the project is complex, the wind tunnel of the measured object is large and irregular, the ladder platform is arranged outside the tunnel body, the measurement and control cabinet is arranged outside the tunnel body, and the infrared temperature measuring camera is arranged on the wall around the wind tunnel, so that the ladder platform and the measurement and control cabinet can shield infrared imaging, and the appearance of the measured object is shown in the following figure. Therefore, the single-use visual temperature measurement is difficult to accurately measure and completely covers the surface of the hole body, the auxiliary temperature measurement is needed to be carried out by matching with an optical fiber temperature measurement system, and finally the re-detection is carried out by matching with a manual handheld infrared thermometer, so that the accurate temperature measurement and positioning are realized.
(3) Multi-source heterogeneous data fusion. The method is characterized in that fusion of infrared image data and optical fiber temperature measurement data is required to be realized, unified mapping of the temperature measurement data to a wind tunnel 3D model is realized, 3D display is performed after grid division is performed according to the wind tunnel three-dimensional model, a wind tunnel surface temperature field is displayed in a thermal pattern mode, and a cooling leakage area is marked.
The resolution of the visual data is higher but the temperature measurement accuracy is relatively lower, the resolution of the optical fiber temperature measurement data is lower but the temperature measurement accuracy is relatively higher, and the output modes of the two data are greatly different, so that great difficulty is brought to fusion; in addition, the number of system equipment is large, the amount of fusion data is large, and the fusion difficulty is high.
In order to solve the above problems, this embodiment provides a wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combination temperature measurement as shown in fig. 1, the system mainly includes:
the visual temperature measurement subsystem is used for acquiring a temperature field image of the surface of the wind tunnel;
the optical fiber temperature measurement subsystem is used for measuring the temperature of a measurement blind area of the optical fiber temperature measurement subsystem on the surface of the wind tunnel;
the temperature correction subsystem is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem;
and the 3D display subsystem is used for displaying the three-dimensional temperature field and the cold leakage point position of the wind tunnel surface on the wind tunnel 3D model in real time.
The specific arrangement of each subsystem is as follows:
visual temperature measurement subsystem: the main hardware comprises an infrared/visible double-light camera (i.e. a double-spectrum camera), a high-speed transmission optical fiber, a gigabit network switch, an NVR network server, a data processing server and the like, wherein the gigabit network switch and a related power supply and control module are installed in a measuring cabinet, and the NVR network server and the data processing server are installed in a measuring and controlling cabinet. The software system comprises a data acquisition and transmission module, a dual-light camera calibration module, an image fusion positioning module, an AI abnormal region identification module, a GPU hardware acceleration module and a three-dimensional temperature field mapping module.
Distributed optical fiber temperature measurement subsystem: the main hardware comprises a distributed optical fiber temperature measuring host (DTS), a temperature measuring optical fiber, a gigabit network switch, a data processing server (shared), and the like, wherein the distributed optical fiber temperature measuring host (DTS) is arranged in a measuring cabinet. The system software comprises a distributed optical fiber testing system data acquisition module, a data transmission module, a cold leakage detection module, an optical fiber positioning calibration module, a wind tunnel 3D fusion module and the like.
3D display subsystem: the hardware comprises a data processing server (shared), a measurement and control cabinet, a data information display device, a man-machine interface input device and the like. The software part comprises a data fusion module, a data display module, an interface interaction module, a playback comparison module and a user information module.
Temperature correction subsystem: the infrared thermal imaging system comprises a blackbody correction module, a temperature correction evaluation module and a handheld thermal infrared imager.
The workflow of the system is shown in fig. 9:
system preparation stage: firstly, software and hardware are distributed, and after the distribution is completed, system connectivity test is carried out. And if the connectivity test is free of problems, starting to calibrate the system, including calibration of a camera and calibration of a temperature measuring optical fiber.
And a data acquisition stage: the dual-optical camera and the distributed optical fiber begin to synchronously collect data and respectively transmit the data from the corresponding tera-mega network switch and the gigabit network switch through the high-speed optical fiber. Image data collected by the double-light camera is transmitted to an NVR network video storage server through a switch, stored in the storage server, compressed, subjected to image preprocessing and the like, and then transmitted to a data processing server. The optical fiber data is directly transmitted to the data processing server.
Data fusion stage: the data processing server will fuse the visible light with the infrared data and map the two-dimensional infrared image to the three-dimensional model surface. And then, carrying out cold leakage monitoring through a deep learning algorithm, and carrying out algorithm acceleration through a GPU. The optical fiber data is positioned on the surface of the three-dimensional cavity by installing a cooperation mark on the temperature measuring optical fiber, and the optical fiber temperature measuring data is mapped to the surface of the three-dimensional cavity.
And (3) a display stage: and merging the visual temperature measurement data with the optical fiber temperature measurement data, directly mapping the monitoring result to the surface of the wind tunnel 3D model, displaying an abnormal region in a warning manner, and giving the number of the heat insulation block at the position of the leakage point.
Example 2:
based on the wind tunnel cold leakage monitoring system of embodiment 1, the embodiment optimizes the visual temperature measurement subsystem:
according to the requirements of the tunnel factory building in the embodiment, the imaging equipment in the visual temperature measurement subsystem is arranged on the side wall of the tunnel factory building, so that reasonable layout is realized, and the observation of the upper surface of the tunnel body is realized to the maximum extent.
Camera layout takes into account several factors: (1) the camera layout needs to cover the upper surface of the cavity; (2) When the cameras are arranged, infrared temperature measurement errors caused by irradiation angles of the double-light cameras need to be considered, and a basis is provided for optical fiber arrangement; (3) Because the embodiment is a reflux wind tunnel, when the camera is arranged around the wind tunnel factory building wall, the external surface of the outer side of the near hole (close to the wall) and the external surface of the inner side of the far hole (not close to the wall) need to be considered, so that the camera can be reasonably used for monitoring.
As shown in fig. 2, the outer surface of the wind tunnel with the perimeter of about 200m is divided into 18 areas, the infrared temperature measurement of the corresponding areas is carried out by 18 double-light cameras respectively, the 18 double-light cameras are all installed at the high positions of the surrounding factory building walls, and the heights are divided into two groups according to the areas responsible for the two double-light cameras:
(1) the total number of cameras with the numbers of C1, C2, C3, C5, C8, C10, C11, C13, C16 and C18 is 10;
(2) the total of 8 cameras numbered C4, C6, C7, C9, C12, C14, C15 and C17.
The embodiment is a reflux wind tunnel, so that the height of the double-light camera responsible for monitoring the outer surface pipeline is lower, and the height of the double-light camera responsible for monitoring the inner surface pipeline is higher, so that the two groups of cameras are matched with each other, a certain public view field exists, the public view field is not overlarge, and the visible surface of the pipeline is covered as large as possible. In order to avoid that the line of sight of the opposite camera is blocked by the section of pipeline, the installation position of the corresponding camera is higher than that of other cameras for the thicker section of pipeline in the reflux wind tunnel.
In the scheme, all the bifocal cameras sequentially cruise and observe from high altitude according to a preset point position planned in advance through rotation of a cradle head at a overlook angle; each camera is responsible for designating an area, and a corresponding preset bit is set for cruising observation.
Because the surface to be measured is a curved surface target, when the dual-light camera measures the target surface at a non-positive angle, i.e. the target surface is not perpendicular to the optical axis of the camera, the effective pixel number of the surface to be measured on the infrared sensor has an equivalent proportionality coefficient (wherein is the included angle between the tangential plane of the camera surface and the optical axis), and the measurement is performed based on the identification standard of 6 pixels in the Johnson criterion.
Based on the effective temperature measurement area, the installation of two opposite dual-light cameras in each group is shown in fig. 3, the inferior arc of the AB section is the effective temperature measurement area of the camera C1, the inferior arc of the CD section is the effective temperature measurement area of the camera C2, and the included angle alpha is the limit included angle of 20 degrees of the effective temperature measurement area of the camera.
In order to achieve the best measurement effect, two groups of cameras are matched with each other, a certain common view field exists, and the common view field is not too large, so that the effective measurement areas of the cameras on the two sides of the visible surface of the pipeline are covered as large as possible, the edge of the effective measurement areas is ensured to be about 0.5m long, namely, the BC segment minor arc is an overlapping area, and the circumferential length of the BC segment is 0.5m.
It should be noted that, for the backflow wind tunnel, it is also necessary to verify that the camera on the peripheral wall is shielded by the same side pipe when monitoring the temperature of the inner wall of the side pipe.
Example 3:
based on the wind tunnel cold leakage monitoring system of embodiment 2, the embodiment optimizes the optical fiber temperature measurement subsystem:
the optical fiber temperature measurement subsystem in this embodiment is composed of a distributed optical fiber temperature measurement host (such as ATDTS-MK), a temperature measurement optical fiber (such as MGTSV-2 A1), a gigabit network switch and a data processing server (the data server of the same vision temperature measurement subsystem), and is responsible for measuring the temperature of the surface area which is not covered by the vision subsystem, detecting the cold leakage condition of the surface of the tunnel, and positioning the position of the tunnel leakage.
The optical fiber temperature measurement subsystem comprises a temperature measurement optical fiber which is spirally paved at the lower part of the wind tunnel, and as shown in fig. 4 and 5, the temperature measurement optical fiber covers a measurement blind area of the visual temperature measurement subsystem on the surface of the wind tunnel; and the top end convolution part of the temperature measuring optical fiber enters the effective temperature measuring area. And a plurality of optical fiber measurement key points are distributed on the temperature measuring optical fiber at equal intervals, and redundant sections are distributed on the temperature measuring optical fiber at equal intervals.
In the embodiment, the optical fiber measurement key points (redundancy 1 m) are reserved at intervals of 100 m and used as temperature measurement standard points, and meanwhile, the optical fiber system is ensured to overcome the influence of thermal deformation of the hole body. By adopting the optical fiber convolution laying scheme, the optical fiber laying interval distance is 0.5m, and the joint of the optical fiber laying interval distance and the heat insulation block with the size of 1m square is kept consistent, so that the optical fiber can effectively cover the gap of the joint of the heat insulation block, the detection accuracy of the cold leakage area is improved, and the detection area accuracy reaches the standard. In the surface section of the cavity with other objects such as ladder/platform, the winding height of the optical fiber exceeds the height of the ladder/platform by 0.5 meter.
According to the laying principle, the temperature measuring optical fiber in the embodiment is higher than the inferior arc section AD of the surface of the hole which cannot be covered by the double-light camera in FIG. 3 by 0.5m, namely, the laying position and the height of the optical fiber are the marked thick section in FIG. 3.
The functions of the optical fiber temperature measurement subsystem in this embodiment include:
(1) The data acquisition and transmission function is realized by the data acquisition and transmission module, and the original temperature measurement optical signal data of the temperature measurement optical fiber arranged on the surface of the cavity body is acquired and transmitted to the DTS host through the optical cable; the processed temperature measurement electric data is transmitted to a data processing server by a gigabit network switch; in order to ensure the expandability of the system, the switch is adopted to transmit the temperature measurement electric data, and a plurality of DTSs and corresponding temperature measurement optical fibers can be accessed at any time.
(2) And the data storage and processing function is that the data storage and processing module processes the collected temperature measurement optical signal data in the DTS host computer to obtain a temperature measurement electric signal, and the temperature measurement electric signal is transmitted to the data processing server for storage.
(3) And the calibration function of the optical fiber test system is realized by a calibration module of the optical fiber test system, and the calibration of the length and the temperature measurement distance on the temperature measurement optical fiber is realized.
(4) And the measurement result and the wind tunnel 3D model are associated, and the calibration and association of the temperature measured by the optical fiber and the position of the wind tunnel model are realized on a data processing server by the optical fiber temperature measurement three-dimensional positioning module.
(5) And the cold leakage monitoring function is to detect and position the abnormal temperature part of the optical fiber in the DTS host after the temperature measurement electric signal is obtained by the cold leakage monitoring module through data processing, and to detect and position the abnormal temperature part of the surface of the three-dimensional hole on the data processing server.
Example 4:
on the basis of any of the above embodiments, the present embodiment optimizes the temperature correction subsystem:
the temperature correction subsystem is mainly used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem and comprises a blackbody correction module, a temperature correction evaluation module and a handheld thermal infrared imager.
The blackbody correction module is mainly used for continuously correcting the infrared temperature measurement camera so as to ensure the temperature measurement precision. The blackbody is a constant temperature target and is used for continuously correcting the infrared temperature measurement of the double-light camera so as to ensure the temperature measurement precision, the blackbody is arranged in the visual field of the double-light camera, the blackbody is used for measuring the temperature, and the temperature measurement calibration is carried out in real time by taking the blackbody as a reference. The portable blackbody correction module is adopted in the project, and can be arranged on a tripod for installation. When temperature correction is carried out, the black body is arranged at a fixed position, and after the camera is corrected, the black body is arranged at the next camera calibration position, so that the next double-light camera is corrected.
The temperature correction evaluation module mainly comprises a first temperature sensor arranged on the surface of a wind tunnel shell, 4 parts are distributed, the surface temperature of the wind tunnel shell is monitored in real time on line and used for correcting and evaluating test data of a visual temperature measurement system and an optical fiber temperature measurement system, in addition, a second temperature sensor is arranged at the periphery of the wind tunnel, the ambient temperature is monitored in real time, and the ambient temperature is used as a local reference temperature when a cold leakage detection algorithm is constructed.
Example 5:
on the basis of any of the above embodiments, the present embodiment optimizes a 3D display subsystem:
the 3D display subsystem is mainly used for displaying the result of cold leakage detection and displaying the three-dimensional temperature field and the position of the cold leakage point on the wind tunnel 3D model in real time.
The 3D display subsystem shares a data processing server with the visual temperature measuring subsystem and the optical fiber temperature measuring subsystem, and fusion processing is carried out on the visual temperature measuring data and the optical fiber temperature measuring data; and uniformly mapping the temperature measurement data onto a wind tunnel 3D model, carrying out data fusion on the overlapping measurement area, carrying out 3D display after carrying out grid division according to the wind tunnel three-dimensional model, displaying the wind tunnel surface temperature field in a thermal pattern mode, and marking the cooling leakage area.
The 3D display subsystem adopts a data fusion technology to fuse the data of the visual temperature measurement and the optical fiber temperature measurement. The fusion belongs to decision-level fusion, primary conclusions are respectively obtained on the wind tunnel surface temperature information through an infrared camera and a distributed optical fiber, then decision-level fusion judgment is carried out through association processing, and finally fusion-type wind tunnel surface temperature information is obtained. And meanwhile, a data interpolation algorithm is adopted to map the fused temperature image to a wind tunnel 3D model in a fusion way, so that the surface temperature field of the wind tunnel is displayed in a heat map mode.
The functions of the 3D display subsystem mainly comprise fusion of infrared temperature measurement and optical fiber temperature measurement data at an overlapping part and mapping of a three-dimensional temperature field.
The method comprises the following steps of (1) fusing infrared temperature measurement and optical fiber temperature measurement data at an overlapping part:
in the blind area of infrared temperature measurement, the infrared camera can not shoot and obtain data. Thus, a temperature measurement is performed using the laid optical fiber. At the edge of the fiber layout, there is a partial overlap between the infrared camera and the fiber area, and therefore, data fusion is required.
The infrared camera can shoot the temperature change in continuous space, and the measurement accuracy is lower than that of an optical fiber. Optical fibers can accurately measure temperature, but fiber routing limitations result in single point data being measured by the optical fibers.
The point values in fig. 6 are the temperatures measured by the optical fibers, and the curved surface is the temperature field measured by the infrared camera. The temperature resolution measured by the infrared camera is higher, and the data mapping is smoother; and the temperature measured by the optical fiber is more accurate. Therefore, the scheme adopts the optical fiber data at the positions with the optical fiber data, and the point data is obtained by adopting an interpolation method at the points among the optical fiber data. The curved surface adopted by interpolation is obtained by fitting infrared camera data. The data of the fitted curved surface at the corresponding point of the optical fiber is the temperature measured by the optical fiber, and the change trend of the data is the same as the data of the infrared camera; the infrared camera provides a trend of temperature change corresponding to the accurate temperature value provided by the optical fiber data.
According to the embodiment, through effective and reasonable deployment of infrared temperature measurement and optical fiber temperature measurement equipment, the surface of the hole body is covered to the greatest extent, only the shielded place and the lower half part of the hole body cannot be detected, so that seamless, missing-free and error-free cold leakage monitoring is guaranteed, and meanwhile, the redundancy of a system is reduced, and the waste of system computing resources is reduced.
(II) mapping of three-dimensional temperature fields:
this embodiment requires that the infrared image be mapped onto the wind tunnel three-dimensional model, since the resolution of the infrared image is only 640 x 512, and the number of pixels inside the surface of the wind tunnel three-dimensional model is much higher than the resolution of the infrared image. Therefore, interpolation in the wind tunnel three-dimensional model panel is needed to map the temperature field. Meanwhile, the interval of optical fibers arranged at the bottom of the wind tunnel is 0.4m, and the square size of the 3D model is 0.25mX0.25m. Therefore, data interpolation is also required at the time of model display.
The item adopts a bicubic interpolation method to conduct data interpolation, so that the texture transition is more uniform, the sawtooth effect is minimum, and the image effect is best.
The principle of bicubic interpolation is as follows:
assuming that the source image a has a size of mxn, the scaled target image B has a size of mxn. The corresponding coordinates of B (X, Y) on a can be found from the scale item as:
A(x,y)＝A(X×(n/M),Y×(n/M))
in bilinear interpolation, the item selects the nearest four points of A (x, y). In bicubic interpolation, the item selects the nearest 16 pixels as the parameter for calculating the pixel value at the target image B (X, Y), as shown in fig. 7.
In FIG. 7, the point P is the position of the target image B in the (X, Y) corresponding to the source image A, and the coordinate position of P is a fractional part, so the item assumes that the point P has the coordinates P (x+u, y+v), where X, Y respectively represent integer parts, u, v respectively represent fractional parts. Then the position of the nearest 16 pixels as shown can be obtained, using a ij (i, j=0, 1,2, 3).
The purpose of bicubic interpolation is to find out the influence factor of the 16 pixels on the pixel value at the P position by finding out a coefficient, so that the pixel value of the corresponding point of the target image is obtained according to the influence factor, and the purpose of image scaling is achieved. The calculation formula is as follows:
wherein f (x, y) is the pixel value of the interpolated P point, x i ，y i For pixel coordinates in the 4 x 4 range around the P point, f (x i ，y i ) Is a pixel value corresponding to a pixel coordinate in the 4 x 4 range. It can be seen that bicubic interpolation is based on weighting the surrounding 16 pixels.
The calculation method of the interpolation coefficient W is as follows:
wherein a= -0.5. The function diagram is shown in fig. 8.
According to the embodiment, mapping is carried out by a bicubic interpolation method, 3D display is finally carried out after grid division is carried out according to a wind tunnel three-dimensional model, a wind tunnel surface temperature field is displayed in a thermal pattern mode, and a cold leakage area is marked. According to the camera layout scheme, the minimum pixel number of a 0.25 m-sized target in a camera is 15.2 pixels, targets far larger than 6 pixels are identified, and the resolution of the 3D display grid of the threshold wind tunnel reaches 0.25mX0.25m finally through three-dimensional temperature field mapping.
The foregoing description of the embodiments has been provided for the purpose of illustrating the general principles of the application, and is not meant to limit the scope of the application, but to limit the application to the particular embodiments, and any modifications, equivalents, improvements, etc. that fall within the spirit and principles of the application are intended to be included within the scope of the application.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. In addition, the term "coupled" as used herein may be directly coupled or indirectly coupled via other components, unless otherwise indicated.
Claims (8)
1. Wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combination temperature measurement, which is characterized by comprising:
the visual temperature measurement subsystem is used for acquiring a temperature field image of the surface of the wind tunnel;
the optical fiber temperature measurement subsystem is used for measuring the temperature of a measurement blind area of the optical fiber temperature measurement subsystem on the surface of the wind tunnel;
the temperature correction subsystem is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem;
the 3D display subsystem is used for displaying the three-dimensional temperature field and the cold leakage point position of the wind tunnel surface on the wind tunnel 3D model in real time;
the 3D display subsystem includes:
the visual temperature measurement processing module is used for processing the temperature field data acquired by the visual temperature measurement subsystem;
the optical fiber temperature measurement processing module is used for processing temperature data obtained by measurement of the optical fiber temperature measurement subsystem;
the fusion module is used for fusing the temperature data of the overlapping measurement area of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem;
the mapping module is used for mapping the fused temperature data to the wind tunnel 3D model;
the display module is used for displaying the surface temperature field of the wind tunnel in a thermal pattern mode;
the method for mapping the fused temperature data onto the wind tunnel 3D model is a bicubic interpolation method, comprising the following steps:
setting the P point as the position of the target image in the (X, Y) position corresponding to the source image; the P point coordinates are P (x+u, y+v), wherein x and y respectively represent integer parts, and u and v respectively represent decimal parts;
and (3) calculating:
wherein f (x, y) is the pixel value of the P point after interpolation; x is x i ，y i Pixel coordinates in a 4 x 4 range around the P-point; i=0, 1,2,3; f (x) i ，y i ) Pixel values corresponding to pixel coordinates within a 4 x 4 range; w is an interpolation coefficient, and the value of the interpolation coefficient is as follows:
wherein a= -0.5.
2. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 1, wherein the vision temperature measurement subsystem is further used for acquiring a texture image of the surface of the hole.
3. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 1, wherein the vision temperature measurement subsystem comprises a plurality of groups of two-light cameras which are arranged outside the wind tunnel in pairs; the double light of the double-light camera is infrared light and visible light;
each double-light camera is provided with an effective temperature measuring area for infrared temperature measurement of the surface of the wind tunnel, and the effective temperature measuring areas of the two opposite double-light cameras in each group are partially overlapped;
the installation height of all the double-light cameras is higher than the top of the wind tunnel, and the measuring area of the visual temperature measuring subsystem at least covers the upper surface of the wind tunnel.
4. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 3, wherein the effective temperature measurement area is obtained based on Johnson criterion measurement; each dual-light camera has a matched pan-tilt.
5. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 3, wherein the optical fiber temperature measurement subsystem comprises a temperature measurement optical fiber which is circularly paved at the lower part of the wind tunnel, and the temperature measurement optical fiber covers a measurement blind area of the vision temperature measurement subsystem on the surface of the wind tunnel; and the top end convolution part of the temperature measuring optical fiber enters the effective temperature measuring area.
6. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 5, wherein a plurality of optical fiber measurement key points are distributed on the temperature measurement optical fiber at equal intervals, and redundant sections are distributed on the temperature measurement optical fiber at equal intervals.
7. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combination temperature measurement according to claim 1, wherein the temperature correction subsystem comprises:
the blackbody correction module comprises a blackbody arranged in the visual field range of the visual temperature measurement subsystem and is used for correcting the measured temperature of the visual temperature measurement subsystem;
the temperature correction evaluation module comprises a plurality of first temperature sensors arranged on the surface of the wind tunnel and a plurality of second temperature sensors arranged around the wind tunnel; the first temperature sensor is used for correcting and evaluating temperature measurement data of the visual temperature measurement subsystem and the optical fiber temperature measurement subsystem, and the second temperature sensor is used for monitoring the environmental temperature in the wind tunnel factory building;
the handheld thermal infrared imager is used for carrying out secondary detection on the position of the cold leakage point.
8. The wind tunnel cold leakage monitoring system based on vision and distributed optical fiber combined temperature measurement according to claim 1, wherein the temperature data fusion method of the overlapping measurement area of the vision temperature measurement subsystem and the optical fiber temperature measurement subsystem comprises the following steps:
extracting optical fiber data points obtained by optical fiber temperature measurement;
and obtaining temperature data among the optical fiber data points by adopting a data interpolation algorithm, wherein a curved surface adopted by the data interpolation algorithm is obtained by fitting measurement data of a visual temperature measurement subsystem.
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