Laser imaging freezing rain identification device and identification method based on prism refraction

Abstract

The invention discloses a laser imaging freezing rain identification device and identification method based on prism refraction, and belongs to the technical field of power cables, the identification device comprises a first imaging unit, a second imaging unit and a control unit; the first imaging unit and the second imaging unit are oppositely arranged, a slit is formed between the first imaging unit and the second imaging unit, and the horizontal plane of the slit is perpendicular to the ground surface; the first imaging unit is used for emitting pulse laser and horizontally transmitting a light beam of the pulse laser to the slit; the second imaging unit is used for receiving the light beam of the pulse laser in the slit and imaging; the control unit is used for controlling the first imaging unit and the second imaging unit, processing imaging results and judging whether freezing rain occurs or not. According to the laser imaging freezing rain identification device and identification method based on prism refraction, freezing rain particle monitoring with high precision, high real-time performance and strong anti-interference performance is realized, and the accuracy of freezing rain disaster early warning is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of power cables, and in particular to a laser imaging freezing rain recognition device and a recognition method based on prism refraction. Background Art

[0002] As global climate change intensifies, extreme weather events occur frequently. Among them, freezing rain, as a special form of precipitation phenomenon, poses a great safety hazard to transportation, power transmission and other fields in winter. Traditionally, the monitoring of freezing rain mainly relies on meteorological radars, ground observation stations and other means. Although these methods can provide meteorological information over a large area, it is difficult to accurately monitor local small-scale freezing rain phenomena. In addition, due to the strong randomness and locality of freezing rain, traditional monitoring methods often cannot provide early warning information in a timely and accurate manner, resulting in delayed emergency response and increased disaster losses.

[0003] When freezing rain falls, it forms a thick layer of ice covering the power lines, which greatly increases the weight of the cables. As the ice accumulates, the load on the wires will exceed their designed carrying capacity, causing the cables to sag or even break. In addition, the towers may also tilt or collapse due to excessive tension. In this case, not only will it cause power outages, but it may also pose a threat to the surrounding infrastructure and personal safety. Therefore, timely detection and removal of ice accumulation is crucial to ensure the safe operation of the power system.

[0004] Traditional freezing rain monitoring technology has the following main shortcomings: First, the monitoring accuracy is not high, and it is difficult to accurately capture the specific location and intensity changes of freezing rain; second, the monitoring cost is high, and a large number of ground stations are required to achieve a certain coverage density; third, the response speed is slow, and it is impossible to feedback the freezing rain situation in real time, which affects the decision-making efficiency. In recent years, with the development of optical technology, freezing rain monitoring technology based on optical principles has gradually become a research hotspot. These technologies can improve monitoring accuracy and response speed to a certain extent, but there are still some limitations, such as high equipment complexity and susceptibility to interference from ambient light. At the same time, the existing laser imaging freezing rain recognition device also has the problem of short laser service life and easy damage to the camera when the laser and the camera are shot together. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides a laser imaging freezing rain identification device and identification method based on prism refraction to solve the existing problems raised in the above-mentioned background technology. To achieve the above-mentioned purpose, the present invention provides the following technical solutions:

[0006] A laser imaging freezing rain identification device based on prism refraction comprises a first imaging unit, a second imaging unit and a control unit; the first imaging unit and the second imaging unit are arranged opposite to each other, and a slit is formed between the two, and the horizontal plane of the slit is perpendicular to the ground surface; the first imaging unit is used to emit a pulsed laser and transmit the pulsed laser beam horizontally to the slit; the second imaging unit is used to receive the pulsed laser beam in the slit and form an image; the control unit is used to control the first imaging unit and the second imaging unit, and process the imaging results to determine whether freezing rain occurs.

[0007] Furthermore, the first imaging unit includes a first disk surface, a first prism and a laser arranged in sequence from top to bottom; the first disk surface, the first prism and the laser are located on the same axis; the laser is used to emit pulsed laser, and the first prism is used to turn the direction of the light beam emitted by the laser by 90 degrees and then emit it from the center of the first disk surface and enter the slit.

[0008] Furthermore, the second imaging unit includes a second disk, a second prism, a lens, a filter and a camera arranged in sequence from top to bottom; the second disk, the second prism, the lens, the filter and the camera are located on the same axis; the second prism turns the direction of the light beam in the slit by 90 degrees and then enters the lens, and after filtering out the ambient light interference through the filter, the camera forms an image.

[0009] Furthermore, the second disk surface and the first disk surface are disk-shaped structures, and heating devices are installed inside the second disk surface and the first disk surface.

[0010] Furthermore, the control unit includes a host, and the control unit is communicatively connected with the first imaging unit and the second imaging unit respectively; the first imaging unit and the second imaging unit transmit signals through an optical path.

[0011] Furthermore, the laser is a pulsed laser.

[0012] Furthermore, the lens is a telecentric lens.

[0013] Furthermore, the filter is a near-infrared bandpass filter.

[0014] The laser imaging freezing rain recognition method based on prism refraction adopts the above-mentioned laser imaging freezing rain recognition device based on prism refraction, and comprises the following steps:

[0015] S1, the host starts the laser and controls the laser to emit laser;

[0016] S2, the laser beam is turned 90 degrees by the first prism and then emitted from the center of the first disk surface, passing through the slit between the first disk surface and the second disk surface;

[0017] S3, the laser beam is redirected 90 degrees by the second prism and then enters the lens. After passing through the lens, a clear image is formed in the camera, and the ambient light interference is filtered out by the filter;

[0018] S4, collecting an image without freezing rain through S1-S3 as a background image; collecting an image with freezing rain through S1-S3 as a target image; calling a freezing rain particle image recognition program through the host, calculating a difference image between the background image and the target image, and obtaining the size and velocity parameter data of the freezing rain particles;

[0019] S5. Turn off the laser through the host and wait for the next cycle of collection and calculation.

[0020] Furthermore, in S4, the host computer calls a freezing rain particle image recognition program to calculate a difference image between the background image and the target image to obtain the size and velocity parameter data of the freezing rain particles, which specifically includes:

[0021] The image collected by the host when there is no freezing rain is used as the background image I b save;

[0022] The image collected by the host when freezing rain occurs is used as the background image I t save;

[0023] The difference image I d The calculation formula is: d =I b -I t , through the difference image I d , using image processing algorithms to identify the shadow area of ​​the image and extract the contours of the freezing rain particles F(I b ,I t ), the formula is: F(I b ,I t )=Morphology(Binarize(G(|I b -I t |,σ),T)), where G is the Gaussian filter function, σ is the standard deviation of the Gaussian kernel, T is the dynamic threshold, Binarize is the binarization function, and Morphology is the morphological function; through F(I b ,I t ) obtain the position of the freezing rain particles, and calculate the size A and flow velocity v of the freezing rain particles;

[0024] The formula for the size A of the freezing rain particles is: A = N × d 2, where N is the difference image I d The number of pixels in the shadow area, d is the pixel size;

[0025] The flow velocity v of the freezing rain particles is given by: Among them, (x1, y1) and (x2, y2) are the coordinates of the freezing rain particles in the two frames of images, and t1 and t2 are the acquisition times of the two frames of images.

[0026] The beneficial effects of the present invention are:

[0027] 1. The present invention solves the problems of unstable imaging quality and susceptibility to background light in traditional optical monitoring technology by using a telecentric lens and a near-infrared bandpass filter; the telecentric lens can ensure that the image magnification is constant during the imaging process, avoiding image distortion caused by distance changes, while the near-infrared bandpass filter can effectively filter out visible light and other wavelengths of interfering light, allowing only specific wavelengths of light to pass, further improving the imaging quality. This combined design not only improves the contrast and clarity of the image, but also enables the system to work normally at night or in low light conditions, greatly expanding the scope of application.

[0028] 2. The present invention performs difference processing on the background image and the target image through the host, thereby solving the problem that the traditional method cannot accurately identify the freezing rain particles. The host collects the background image when there is no freezing rain, and collects the target image when freezing rain occurs. By calculating the difference image between the two, the image processing algorithm is used to identify the outline of the freezing rain particles, and then the size and flow rate of the freezing rain particles are calculated. This method can not only quickly and accurately identify the freezing rain particles, but also monitor their dynamic changes in real time, providing a scientific basis for disaster warning and greatly improving the timeliness and effectiveness of monitoring.

[0029] 3. The present invention solves the problems of inconvenient installation and poor adaptability of traditional freezing rain monitoring equipment through a freely adjustable modular design. The device is divided into an upper half and a lower half, which communicate through a wired connection, and the installation position can be freely adjusted. This design not only facilitates the installation and maintenance of the equipment, but also can flexibly adjust the position of each component according to actual needs, thereby improving the flexibility and adaptability of the system. Especially under different terrain and environmental conditions, this modular design can better meet the needs of on-site installation and enhance the practicality of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the planar structure of the laser imaging freezing rain identification device based on prism refraction of the present invention;

[0031] Figure 2 It is a schematic diagram of the three-dimensional structure of the laser imaging freezing rain identification device based on prism refraction of the present invention;

[0032] Figure 3 The present invention is a flowchart of the freezing rain identification method based on laser imaging of prism refraction.

[0033] In the attached figure: 1, second disk; 2, second prism; 3, lens; 4, filter; 5, camera; 6, first disk; 7, first prism; 8, laser; 9, housing; 10, host. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the present invention is not limited to the following embodiments.

[0035] Unless otherwise specified, in the present invention, the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", "x direction", "y direction", "z direction", etc. indicating orientation or position relationship are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the orientation or position relationship in the present invention are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood in conjunction with the drawings and according to specific circumstances.

[0036] Embodiment 1:

[0037] See attached Figures 1 to 3 . The present application discloses a freezing rain identification device based on laser imaging of prism refraction, including a first imaging unit, a second imaging unit and a control unit; wherein the first imaging unit and the second imaging unit are arranged opposite to each other, and a slit is formed between the two, and the horizontal plane of the slit is perpendicular to the ground surface; the first imaging unit is used to emit a pulsed laser and transmit the pulsed laser beam horizontally to the slit, and the second imaging unit is used to receive the pulsed laser beam in the slit and form an image, and the collected freezing rain needs to pass through the slit, which can ensure that the freezing rain particles entering the slit can be clearly imaged. The control unit is used to control the first imaging unit and the second imaging unit, and process the imaging results to determine whether freezing rain has occurred.

[0038] In one embodiment of the present application, Figure 1As shown, the first imaging unit includes a first disk surface 6, a first prism 7 and a laser 8 which are arranged in sequence from top to bottom, and the first disk surface 6, the first prism 7 and the laser 8 are located on the same axis. The laser 8 is used to emit pulsed laser, and the first prism 7 turns the direction of the light beam emitted by the laser 8 by 90 degrees, and then emits it from the center of the first disk surface 6 and enters the slit. The wavelength of the laser emitted by the laser 8 can be 850nm, which avoids damage to the human eye. After the direction of the laser beam emitted by the laser 8 is turned, the laser beam is prevented from directly facing the camera, thereby reducing the damage caused by the laser beam to the photosensitive element of the camera.

[0039] In one embodiment of the present application, Figure 1 As shown, the second imaging unit includes a second disk 1, a second prism 2, a lens 3, a filter 4 and a camera 5 which are arranged in sequence from top to bottom, and the second disk 1, the second prism 2, the lens 3, the filter 4 and the camera 5 are located on the same axis. Preferably, the right-angled sides of the second prism 2 and the first prism 7 are opposite and located on the same central axis, ensuring that the laser beam emitted from the laser 8 can pass through the slit to reach the camera 5. The second prism 2 turns the direction of the light beam in the slit by 90 degrees and then enters the lens 3, and after filtering out the ambient light interference through the filter 4, the camera 5 forms an image. For example, the pixel size of the camera 5 can be 3.45μm, the maximum standard frame rate can be 24, and the resolution can be 2448×2048. The camera 5 has a higher resolution and frame rate, which can make the captured freezing rain particles imaged without distortion.

[0040] In one embodiment of the present application, Figure 2 As shown, the second disk surface 1 and the first disk surface 6 are disk-shaped structures, and a heating device is installed inside the second disk surface 1 and the first disk surface 6. The heating device can prevent the second disk surface 1 and the first disk surface 6 from being frozen by freezing rain when freezing rain occurs, thereby affecting the light path transmission. Preferably, the slit width between the second disk surface 1 and the first disk surface 6 can be 18 mm, and the horizontal plane of the slit is perpendicular to the ground surface when installed, ensuring that the freezing rain particles can pass through the slit during the free fall process so as to be captured by the camera 5.

[0041] In one embodiment of the present application, the control unit includes a host 10, and may also include a box 9 for placing the host 10, and the host 10 completes the image processing function. The host 10 is respectively connected to the first imaging unit and the second imaging unit for communication, for example, through a wired connection; the first imaging unit and the second imaging unit transmit signals through an optical path. The installation position of the control unit can be freely adjusted. Specifically, the host 10 controls the start and stop of the laser 8. At the beginning, the host 10 first uses the collected image as the background image, and then the host 10 collects the image between the first disk surface 6 and the second disk surface 1 as the target image every 30 seconds. The host 10 subtracts the background image and the target image and then calls the subroutine for identifying freezing rain particles to obtain the geometric parameters of the freezing rain particles. The host 10 turns off the laser and waits for the next cycle of collection.

[0042] In one embodiment of the present application, the laser 8 is a pulse laser. The emission power of the pulse laser is reduced, which can increase the service life of the laser 8.

[0043] In one embodiment of the present application, the lens 3 is a telecentric lens, and the object-space resolution of the telecentric lens can be 11.43 microns. The telecentric lens can magnify the freezing rain particles so that they can be clearly imaged in the camera 5.

[0044] In one embodiment of the present application, the filter 4 is a near-infrared bandpass filter. Preferably, the filter 4 can be an 850-nanometer near-infrared bandpass filter. The filter 4 allows the light emitted by the laser 8 to pass smoothly and filters out interference from visible light and ambient light.

[0045] The working principle of the laser imaging freezing rain identification device based on prism refraction disclosed in this application is:

[0046] When there is no freezing rain, the host 10 controls the laser 8 to emit a laser. The laser passes through the second prism 2 to turn the light beam direction 90 degrees and then is emitted from the center of the second disk surface 1, and then passes through the slit between the second disk surface 1 and the first disk surface 6 to reach the first prism 7. The first prism 7 turns the light speed 90 degrees and then enters the telecentric lens, and then forms an image through the camera 5, and the image is saved as the background image.

[0047] When freezing rain occurs, the host 10 controls the laser 8 to emit a laser, which is emitted from the center of the second disk surface 1 after the beam direction is turned 90 degrees by the second prism 2. The freezing rain particles in the slit between the second disk surface 1 and the first disk surface 6 block the laser, and this part of the light cannot enter the camera 5, forming a shadow area in the image. The size of the shadow area is related to the size and shape of the freezing rain particles. The host 10 saves the image formed at this time as the target image. By calculating the difference image between the background image and the target image, the size and flow rate parameter data of the freezing rain particles are obtained.

[0048] The device of this embodiment uses a pulsed laser to emit laser, which is imaged by a telecentric lens after two 90-degree turns, and effectively filters out ambient light interference through a near-infrared bandpass filter. Finally, the camera 5 forms an image, accurately capturing the size and flow rate of freezing rain particles, thereby improving monitoring accuracy and real-time performance, while reducing system complexity and cost, and having high practical value.

[0049] Embodiment 2:

[0050] See attached Figures 1 to 3 Based on the first embodiment, the present application also discloses a method for identifying freezing rain using laser imaging based on prism refraction, such as Figure 3 As shown, the following steps are included:

[0051] S1, the host 10 starts the laser 8 and controls the laser 8 to emit laser;

[0052] S2, the laser beam is turned 90 degrees by the first prism 7 and then emitted from the center of the first disk surface 6, passing through the slit between the first disk surface 6 and the second disk surface 1;

[0053] S3, the laser beam is redirected by the second prism 2 by 90 degrees and then enters the lens 3. After passing through the lens 3, a clear image is formed in the camera 5, and the interference of ambient light is filtered out by the filter 4;

[0054] S4, collecting an image without freezing rain through S1-S3 as a background image, and collecting an image with freezing rain through S1-S3 as a target image; calling a freezing rain particle image recognition program through the host 10, calculating a difference image between the background image and the target image, and obtaining the size and flow rate parameter data of the freezing rain particles;

[0055] S5. Turn off the laser 8 through the host 10 and wait for the next cycle of collection and calculation.

[0056] Specifically, the host 10 calls the freezing rain particle image recognition program, calculates the difference image between the background image and the target image, and obtains the size and flow rate parameter data of the freezing rain particles, which specifically includes:

[0057] The image collected by the host 10 when there is no freezing rain is used as the background image I b save;

[0058] The image collected by the host 10 during freezing rain is used as the background image I t save;

[0059] The difference image I d The calculation formula is: d =I b -I t , through the difference image I d, using image processing algorithms to identify the shadow area of ​​the image and extract the contours of the freezing rain particles F(I b ,I t ), the formula is: F(I b ,I t )=Morphology(Binarize(G(|I b -I t |,σ),T)), where G is the Gaussian filter function, σ is the standard deviation of the Gaussian kernel, T is the dynamic threshold, Binarize is the binarization function, and Morphology is the morphological function; through F(I b ,I t ) obtain the position of the freezing rain particles, and calculate the size A and flow velocity v of the freezing rain particles;

[0060] The formula for the size A of the freezing rain particles is: A = N × d 2 , where N is the difference image I d The number of pixels in the shadow area, d is the pixel size;

[0061] The flow velocity v of the freezing rain particles is given by: Among them, (x1, y1) and (x2, y2) are the coordinates of the freezing rain particles in the two frames of images, and t1 and t2 are the acquisition times of the two frames of images.

[0062] In this embodiment, the host 10 controls the emission of the laser 8 and the imaging of the camera 5, collects the background image and the target image, and calculates the difference image between the two, uses the image processing algorithm to identify the outline of the freezing rain particles, and accurately calculates the size and flow rate of the freezing rain particles; not only the accuracy and real-time performance of the freezing rain particle identification are improved, but also the continuous monitoring capability of the system is ensured by regularly collecting images every 30 seconds, and the system's ability to resist environmental interference and practicality are significantly enhanced, providing an efficient and reliable solution for early warning and response to freezing rain disasters.

[0063] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A laser imaging freezing rain identification device based on prism refraction, characterized in that: The invention comprises a first imaging unit, a second imaging unit and a control unit; the first imaging unit and the second imaging unit are arranged opposite to each other, and a slit is formed therebetween, and the horizontal plane of the slit is perpendicular to the ground surface; the first imaging unit is used for emitting a pulsed laser and transmitting the light beam of the pulsed laser horizontally to the slit; the second imaging unit is used for receiving the light beam of the pulsed laser in the slit and forming an image; the control unit is used for controlling the first imaging unit and the second imaging unit, and processing the imaging results to determine whether freezing rain occurs.

2. The laser imaging freezing rain identification device based on prism refraction according to claim 1 is characterized in that: The first imaging unit comprises a first disk surface (6), a first prism (7) and a laser (8) which are arranged in sequence from top to bottom; the first disk surface (6), the first prism (7) and the laser (8) are located on the same axis; the laser (8) is used to emit pulsed laser light, and the first prism (7) is used to turn the direction of the light beam emitted by the laser (8) by 90 degrees, so that the light beam is emitted from the center of the first disk surface (6) and enters the slit.

3. The laser imaging freezing rain identification device based on prism refraction according to claim 2 is characterized in that: The second imaging unit comprises a second disk (1), a second prism (2), a lens (3), a filter (4) and a camera (5) which are arranged in sequence from top to bottom; the second disk (1), the second prism (2), the lens (3), the filter (4) and the camera (5) are located on the same axis; the second prism (2) turns the direction of the light beam in the slit by 90 degrees and then enters the lens (3), and after filtering out ambient light interference through the filter (4), the camera (5) forms an image.

4. The laser imaging freezing rain identification device based on prism refraction according to claim 3 is characterized in that: The second disk surface (1) and the first disk surface (6) are disk-shaped structures, and heating devices are installed inside the second disk surface (1) and the first disk surface (6).

5. The laser imaging freezing rain identification device based on prism refraction according to claim 4 is characterized in that: The control unit comprises a host (10), and the control unit is communicatively connected with the first imaging unit and the second imaging unit respectively; the first imaging unit and the second imaging unit transmit signals via an optical path.

6. The laser imaging freezing rain identification device based on prism refraction according to claim 2 is characterized in that: The laser (8) is a pulse laser.

7. The laser imaging freezing rain identification device based on prism refraction according to claim 3 is characterized in that: The lens (3) is a telecentric lens.

8. The laser imaging freezing rain identification device based on prism refraction according to claim 3 is characterized in that: The optical filter (4) is a near-infrared bandpass filter.

9. The laser imaging freezing rain identification method based on prism refraction is characterized by: The laser imaging freezing rain identification device based on prism refraction as claimed in claim 5 comprises the following steps: S1, the host (10) starts the laser (8) and controls the laser (8) to emit laser light; S2, the laser beam is turned 90 degrees by the first prism (7) and then emitted from the center of the first disk surface (6) and passes through the slit between the first disk surface (6) and the second disk surface (1); S3, the laser beam is redirected 90 degrees again through the second prism (2) and then enters the lens (3). After passing through the lens (3), a clear image is formed in the camera (5), and the interference of ambient light is filtered out through the filter (4); S4, collecting an image without freezing rain through S1-S3 as a background image; collecting an image with freezing rain through S1-S3 as a target image; calling a freezing rain particle image recognition program through the host (10), calculating a difference image between the background image and the target image, and obtaining the size and flow rate parameter data of the freezing rain particles; S5. Turn off the laser (8) through the host (10) and wait for the next cycle of collection and calculation.

10. The method for identifying freezing rain by laser imaging based on prism refraction according to claim 9, characterized in that: In S4, the host (10) calls a freezing rain particle image recognition program, calculates a difference image between a background image and a target image, and obtains the size and velocity parameter data of the freezing rain particles, which specifically includes: The host (10) uses the image collected when there is no freezing rain as the background image I b save; The host (10) collects an image when freezing rain occurs as a background image I t save; The difference image I d The calculation formula is: d =I b -I t , through the difference image I d , using image processing algorithms to identify the shadow area of ​​the image and extract the contours of the freezing rain particles F(I b ,I t ), the formula is: F(I b ,I t )=Morphology(Binarize(G(|I b -I t |,σ),T)), where G is the Gaussian filter function, σ is the standard deviation of the Gaussian kernel, T is the dynamic threshold, Binarize is the binarization function, and Morphology is the morphological function; through F(I b ,I t ) obtain the position of the freezing rain particles, and calculate the size A and flow velocity v of the freezing rain particles; The formula for the size A of the freezing rain particles is: A = N × d 2 , where N is the difference image I d The number of pixels in the shadow area, d is the pixel size; The flow velocity v of the freezing rain particles is given by: Among them, (x1, y1) and (x2, y2) are the coordinates of the freezing rain particles in the two frames of images, and t1 and t2 are the acquisition times of the two frames of images.

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