Antifouling treatment method for passive reflective target and corresponding image displacement measuring instrument

Abstract

The application discloses a kind of passive reflection target's anti-fouling processing method and corresponding image displacement measuring instrument, a layer of dustproof film is covered on the front of passive reflection target, dustproof film is controlled by film replacement mechanism, film replacement mechanism carries out a film replacement operation every interval time or receives film replacement instruction, and old protective film covered on the front of passive reflection target is removed, while new protective film is covered on the front of passive reflection target.When image displacement sensor judges that passive reflection target is contaminated according to the imaging quality of target image, it sends film replacement instruction autonomously;Or send the result to the control center in remote, and the control center sends film replacement instruction remotely.The application proposes a kind of passive reflection target anti-pollution method, transparent dustproof film is arranged in front of passive reflection target, dust is directly polluted on dustproof film during long-term use, and by regularly replacing the dustproof film, the pollution to internal passive reflection target can be avoided.

Description

Technical Field

[0001] This invention relates to a method for preventing contamination of a passive reflective target and a corresponding image displacement measuring instrument, particularly a method for preventing contamination of a passive reflective target used in slope, tunnel, and bridge displacement monitoring equipment. Background Technology

[0002] In slope, tunnel, and bridge displacement monitoring, image processing-based displacement sensors are commonly used. The basic principle is to set a target at the measurement location and then set up a camera-based displacement sensor at the far end. By capturing the changes in the target's position on the camera image, the displacement parameters of the measured target can be calculated.

[0003] Patent application number 202510085058.9, entitled "A Lightweight Monitoring System for Slope Safety," provides a lightweight monitoring system for slope safety, including a video displacement acquisition system, a video monitoring system, a rainfall acquisition system, a solar power supply system, an alarm module, and a data monitoring center platform. The video displacement acquisition system includes a passive target, a multi-point image displacement measuring instrument, and an infrared supplementary light. The passive target and alarm module are installed on the slope. The multi-point image displacement measuring instrument and the slope are located on opposite sides of the road, with the multi-point image displacement measuring instrument facing the passive target. The video monitoring system, rainfall acquisition system, and solar power supply system are installed on the side where the multi-point image displacement measuring instrument is located. The infrared supplementary light is located on the same side as the multi-point image displacement measuring instrument, facing the passive target, and is used to provide supplementary lighting for the passive target at night.

[0004] The problem is that the passive targets of existing image sensors are usually reflective films (such as 3M reflective films), and their core optical components are microcrystals or glass microbead arrays. During long-term use, surface dust contamination can affect the imaging of the remote image displacement measuring instrument. Figure 1 The image presents a photograph of an existing passive target exhibiting unclear imaging due to contamination. The upper part of the image shows a photograph of the actual target, while the lower part shows the image quality from a distant image sensor. Clearly, the target becomes unusable after severe contamination, even with distant illumination. Regular cleaning by personnel presents high maintenance costs and potential disruption to traffic, limiting the widespread adoption of this target. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preventing contamination of a passive reflective target and a corresponding image displacement measuring instrument. By setting a transparent dustproof film in front of the passive reflective target, the film material is uniformly transparent and will not affect the measurement of the displacement sensor. During long-term use, dust will directly contaminate the dustproof film. By periodically replacing the dustproof film, contamination of the internal passive reflective target can be avoided.

[0006] The technical solution of the present invention is as follows: A method for preventing contamination of a passive reflective target is characterized by: covering the front of the passive reflective target with a dustproof film, which is controlled by a film replacement mechanism. The film replacement mechanism performs a film replacement operation every certain period of time or after receiving a film replacement instruction, removing the old protective film covering the front of the passive reflective target and simultaneously covering the front of the passive reflective target with a new protective film.

[0007] In the above-mentioned anti-fouling treatment method for passive reflective targets, an image displacement sensor images the passive reflective target and exchanges information wirelessly. When the image displacement sensor determines that the passive reflective target is contaminated based on the imaging quality of the target, it generates a target contamination signal inside the sensor and autonomously sends a film replacement command to the passive reflective target; or it sends the contamination signal to a remote control center, which then remotely sends a film replacement command to the film replacement mechanism of the passive reflective target.

[0008] The image displacement sensor images the passive reflective target. When the image displacement sensor determines that the passive reflective target is contaminated based on the imaging quality of the target image, it autonomously sends a coating replacement command; or it sends the result to a remote control center, which then remotely sends a coating replacement command.

[0009] In the above-mentioned method for preventing contamination of passive reflective targets, the film replacement mechanism includes a housing and an active roller, a driven roller, a dustproof film, a motor unit, and a control module disposed inside the housing; A cover plate is installed at the front end of the housing, and the passive reflective target is affixed to the cover plate; The middle part of the dustproof film is the unfolding area, which covers the passive reflective target on the front surface of the cover plate. The two ends of the dustproof film are rolled up and wound around the active roll and the driven roll, respectively. One end of the active roll is equipped with a motor unit, which is electrically connected to the control module. Under the drive of the control module, the motor unit causes the active roll to rotate a set number of times, wrapping the old dustproof film of the unfolding area around the active roll. At the same time, the new dustproof film wrapped on the driven roll is unwound and covered on the passive reflective target.

[0010] In the above-mentioned anti-fouling treatment method for passive reflective targets, the active and passive rollers are set in the housing below the cover plate, and the cover plate has elongated holes on both sides for the dustproof film to pass through.

[0011] In the above-mentioned anti-fouling treatment method for passive reflective targets, two rotating guide rods are installed on both sides of the cover plate or shell, and the dustproof film in the unfolding area is supported at both ends by the two rotating guide rods and then wound on the active and driven rollers.

[0012] In the above-mentioned anti-fouling treatment method for passive reflective targets, the middle part of the rotating guide rod is a round bar, and the two ends are rotating shaft structures supported on the cover plate or the shell; the rotating guide rod is embedded in the elongated hole or installed on the brackets on both sides of the shell.

[0013] In the above-mentioned method for preventing contamination of the passive reflective target, a front panel is installed on the outside of the cover plate, and a gap is provided between the front panel and the cover plate for the dustproof film to pass through; a through hole is opened in the center of the front panel to expose the passive reflective target, and a dust-absorbing pad is provided on the outer ring of the back of the front panel.

[0014] In the above-mentioned anti-fouling treatment method for passive reflective targets, the control module includes a control circuit board and a wireless transceiver module. The control circuit board is equipped with a microcontroller, which is electrically connected to the wireless transceiver module. After the wireless transceiver module receives the film replacement signal sent from the remote end, the microcontroller drives the motor unit to rotate according to the set number of revolutions.

[0015] In the above-mentioned method for preventing contamination of passive reflective targets, the control module includes a battery and a control circuit board. The control circuit board is equipped with a microcontroller, which drives the motor unit to rotate according to a set number of revolutions after a set time interval.

[0016] An image displacement measuring instrument includes a passive reflective target, wherein the passive target is subjected to anti-fouling treatment by the aforementioned anti-fouling treatment method.

[0017] The beneficial technical effects of this invention are as follows: I. This invention proposes a method for preventing contamination using a passive reflective target. By placing a transparent dustproof film in front of the passive reflective target, dust directly contaminates the target during long-term use. By periodically replacing the dustproof film, contamination of the internal passive reflective target can be avoided. Furthermore, the dustproof film is made of a durable film material to ensure it does not degrade or affect light transmittance under prolonged outdoor conditions.

[0018] II. This invention features a simple and reliable film-changing mechanism. The middle portion of the dustproof film is placed over the passive reflective target. Both ends of the dustproof film are rolled up, wound onto an active and a driven roller inside the casing, respectively. Simultaneously, the film-changing mechanism incorporates a microcontroller-controlled motor. At set intervals or upon receiving an external command, the motor unit rotates a set number of revolutions, achieving an automatic film-changing operation and meeting the requirements for long-term outdoor operation. The entire unit adopts a low-power design, with a minimum standby current of 5 microamps, sufficient for over three years of battery power. Furthermore, the compact design, lightweight construction, and easy installation, along with replaceable batteries and film, increase the target's lifespan.

[0019] Third, the film-changing mechanism of this invention enables remote data interaction between the microcontroller, wireless transceiver module, and image displacement sensor host. The image displacement sensor host detects the target contamination status. When contamination is severe, it remotely and autonomously sends a film-changing command wirelessly, or sends the result to a remote control center, which then remotely sends the film-changing command. After receiving the film-changing command, the microcontroller's wireless transceiver module drives the motor unit to rotate according to a set number of revolutions, realizing one film-changing operation. This allows the entire image displacement sensor to operate unattended and be remotely maintained around the clock. Attached Figure Description

[0020] Figure 1 The image shows the actual object and an image of a contaminated passive reflective target from the background art. Figure 2 This is a schematic diagram illustrating the composition principle of the passive reflective target with a replaceable dustproof film of the present invention. Figure 3 This is an external view of the passive reflective target with a replaceable dustproof film according to the present invention. Figure 4 This is a schematic diagram illustrating the composition principle of the membrane changing mechanism of the present invention; Figure 5 This is a schematic diagram of the film changing mechanism with a rotating guide rod on the cover plate of the present invention. Figure 6 This is a schematic diagram of the membrane changing mechanism with a rotating guide rod on the housing of the present invention. Figure 7 This is a schematic diagram of the back of the front panel and the mounting position of the dust collection pad of the present invention; Figure 8 This is a schematic diagram illustrating the principle of sending membrane replacement commands according to the present invention; The attached diagram is labeled as follows: 1-Active roller; 2-Driven roller; 3-House; 4-Dustproof film; 41-Unfolding area; 5-Cover plate; 6-Rotating guide rod; 61-Elongated hole; 62-Bracket; 7-Passive reflective target; 8-Front panel; 81-Through hole; 82-Dust suction pad; 9-Motor unit; 10-Control module; 11-Battery; 12-Mounting bracket; 13-Wireless transceiver module; 14-Image displacement sensor; 15-Fill light; 16-Control center; 17-Camera; 18-Film changing mechanism. Detailed Implementation

[0021] To address the contamination problem of existing passive reflective targets, the project team tried various solutions, such as automatic spray cleaning devices and novel nano-anti-contamination membrane materials, but the results were ultimately unsatisfactory. Based on previous experience, this invention proposes a new anti-contamination approach by adding a dustproof membrane and replacing it periodically.

[0022] The specific anti-fouling method is as follows: A dustproof film is applied to the front of the existing passive reflective target. The dustproof film is a uniform, transparent rolled polyethylene film, and tests have shown that it has almost no impact on the imaging of existing image sensors. A film-changing mechanism is installed on the back of the passive reflective target to control the film changing. The film changing operation is performed every certain period of time or after receiving a command from the remote control module. The old, contaminated protective film covering the front of the passive reflective target is removed, and a new, uncontaminated protective film is applied to the front of the passive reflective target.

[0023] like Figures 2 to 4 As shown, the present invention discloses a passive reflective target with a replaceable dustproof film, comprising a passive reflective target 7 and a film-changing mechanism 18; wherein the film-changing mechanism 18 includes a housing 3 and an active roller 1, a driven roller 2, a dustproof film 4, a motor unit 9, and a control module 10 disposed inside the housing 3. The control module 10 is preferably powered by a battery 11.

[0024] A cover plate 5 is installed at the front end of the housing 3, and the passive reflective target 7 is affixed to the cover plate 5. The middle part of the dustproof film 4 is an unfolding area 41, which covers the passive reflective target 7 on the front surface of the cover plate 5. The two ends of the dustproof film 4 are rolled up and wound around the active roller 1 and the driven roller 2, respectively. The active roller 1 and the driven roller 2 are located inside the housing 3 below the cover plate 5. The cover plate 5 has elongated holes 61 on both sides for the dustproof film to pass through, which can limit the movement of the dustproof film 4. A mounting bracket 12 is also provided at the rear end of the housing 3 for installation and fixation at the measurement position in the tunnel or on the slope.

[0025] To enable periodic film replacement, a motor unit 9 is installed at one end of the active roll 1, which is electrically connected to the control module 10. Driven by the control module 10, the motor unit 9 rotates the active roll 1 a predetermined number of times, the equivalent of which covers the entire passive reflective target 7. The film replacement mechanism 18 winds the old dustproof film from the unfolding area 41 onto the active roll 1, while simultaneously unwinding the new dustproof film from the driven roll 2 and covering the passive reflective target 7. The motor unit includes a reducer and a motor, which is a low-power micro DC motor.

[0026] The dustproof film is made of 0.1-0.2mm thick PET polyester film. This film itself has excellent mechanical strength and chemical resistance, and it also contains UV-resistant and anti-aging additives, effectively resisting ultraviolet degradation and remaining non-yellowing and non-brittle for more than 3 years in outdoor environments. The width is 50-150mm and the length is tens of meters, dimensions sufficient for all existing targets to be used outdoors for 3 years. Measurement tests show that its light transmittance is close to that of the unfilmed version, having almost no impact on the imaging of existing image sensors.

[0027] There are two triggering methods for automatic film replacement: The first is film replacement upon receiving a command. Specifically, the control module 10 includes a control circuit board and a wireless transceiver module. The control circuit board is equipped with a microcontroller, which is electrically connected to the wireless transceiver module 13. After the wireless transceiver module 13 receives a film replacement signal from a remote end, the microcontroller drives the motor unit 9 to rotate a set number of revolutions, thus completing one film replacement operation. The second method is timed film replacement. Specifically, the control module 10 includes a control circuit board equipped with a microcontroller. The microcontroller drives the motor unit 9 to rotate a set number of revolutions at set intervals.

[0028] The control circuit board includes an STM32 microcontroller and peripheral components, primarily responsible for wireless command reception, motor drive, and control of the motor's rotation count. The wireless module is a LoRa long-range transmission module, compatible with the wireless module of the image displacement measurement device. The LoRa module is a low-power wide-area network wireless communication hardware designed specifically for the Internet of Things (IoT), enabling long-distance, highly interference-resistant wireless data transmission with extremely low power consumption. The motor is a low-power micro DC motor. Given the known rotation speed, the number of rotations can be controlled by setting the drive duration through the microcontroller, thereby controlling the movement distance of the dustproof film to precisely cover the entire passive reflective target 7. Simultaneously, the entire control circuit board employs a low-power design, with a minimum standby current of 5 microamps, sufficient for over three years of battery power supply.

[0029] As a further implementation method, such as Figure 5 and Figure 6 As shown, in order to ensure smooth rotation of the roll during film replacement and save battery power, two rotating guide rods 6 are installed on both sides of the cover plate 5 or the housing 3. The middle part of the rotating guide rod 6 is a round rod, and the two ends are rotating shaft structures supported on the cover plate 5 or the housing 3. After the dustproof film 4 in the unfolding area 41 is supported on the two rotating guide rods 6, it is then wound on the active roll 1 and the driven roll 2.

[0030] Figure 5 In the middle, the rotating guide rod 6 is embedded in the elongated hole 61 of the cover plate 5; the middle part of the rotating guide rod 6 is a round bar used to support the dustproof film 4, and the two ends are rotating shafts with a smaller diameter. The rotating shafts are fitted with the round holes at both ends of the elongated hole to achieve rotation. Figure 6 In the housing 3, brackets 62 are machined on both sides corresponding to the positions of the roll shaft, and rotating guide rods 6 are mounted on the brackets 62. The brackets have circular holes, and the rotating shafts at both ends of the circular rod are fitted into these holes with a clearance fit to achieve rotation. The rotating guide rods 6 ensure smooth and reliable rotation of the roll shaft when changing film.

[0031] As a further implementation method, such as Figure 2 and Figure 7As shown, a front panel 8 is mounted on the outside of the cover plate 5, and a gap is provided between the front panel 8 and the cover plate 5 for the dustproof film to pass through. The center of the front panel 8 has a through hole 81 exposing the passive reflective target 7, and a dust-collecting pad 82 is provided on the outer ring of the back of the front panel 8. The dust-collecting pad 82 is made of 3-5mm thick porous sponge and is adhered to the back of the front panel 8. The purpose of providing the gap and installing the dust-collecting pad 82 in the gap is to wipe clean the dust or oil stains on the surface of the dirty dustproof film that enters the housing, effectively reducing the volume of the film wrapped on the active roller 1, thereby extending the overall service life of the device within the limited volume of the housing.

[0032] like Figure 8 As shown, this invention provides a method for autonomous remote control of film replacement. The image displacement sensor 14 in the figure includes a camera 17, a supplementary light 15, and a wireless transceiver module 13. The camera 17 images a passive reflective target 7 remotely mounted on the film replacement mechanism 18. The imaging effect and quality are as follows: Figure 1 As shown, the membrane replacement mechanism 18 is also equipped with a corresponding wireless transceiver module 13. The displacement measurement of the image displacement sensor 14 and the target imaging results are both transmitted to the remote control center 16 through the wireless transceiver module 13. The wireless modules 13 are all paired LoRa long-distance transmission modules.

[0033] When the image displacement sensor 14 determines that the passive reflective target 7 is contaminated based on the imaging quality of the target image, the sensor generates a target contamination signal and autonomously sends a film replacement command to the passive reflective target 7; or it sends the target contamination signal to the remote control center, and the control center 16 remotely sends a film replacement command.

[0034] The contamination status of the passive reflective target 7 is determined based on the average signal amplitude of all pixels in the target image under normal illumination conditions. If the average signal amplitude is less than a set threshold, it will affect displacement measurement, indicating severe contamination of the target and requiring film replacement. In this case, a target contamination signal is generated within the system, for example, marked as Wu_Ran=1. The system then performs autonomous film replacement, or sends the contamination signal to the control center, which, after a decision, sends a film replacement command to the film replacement mechanism of the passive reflective target 7.

[0035] The anti-pollution membrane replacement method of this invention has a clear concept, an ingenious membrane replacement mechanism design, is easy to install, and allows for the replacement of the battery and the roll film, thus meeting the requirements for long-term outdoor operation of passive reflective targets.

Claims

1. A method for preventing contamination of a passive reflective target, characterized in that: A dustproof film (4) is covered on the front of the passive reflective target (7). The dustproof film (4) is controlled by the film replacement mechanism (18). The film replacement mechanism (18) performs a film replacement operation every certain period of time or after receiving a film replacement instruction, removing the old protective film covering the front of the passive reflective target (7) and covering the front of the passive reflective target (7) with a new protective film (4).

2. The method for preventing contamination of a passive reflective target according to claim 1, characterized in that: The image displacement sensor images the passive reflective target (7) and interacts with it wirelessly. When the image displacement sensor determines that the passive reflective target (7) is contaminated based on the imaging quality of the target, it generates a contamination signal inside the sensor and sends a film replacement command to the passive reflective target (7) autonomously. Alternatively, it sends the contamination signal to the remote control center, and the control center (16) remotely sends a film replacement command to the film replacement mechanism (18) of the passive reflective target (7).

3. The method for antifouling treatment of a passive reflective target according to claim 1 or 2, characterized in that: The membrane changing mechanism (18) includes a housing (3) and an active roller (1), a driven roller (2), a dustproof membrane (4), a motor unit (9), and a control module (10) disposed inside the housing (3). The front end of the housing (3) is fitted with a cover plate (5), and the passive reflective target (7) is attached to the cover plate (5). The middle part of the dustproof film (4) is the unfolding area (41), which covers the passive reflective target (7) on the front surface of the cover plate (5). The two ends of the dustproof film (4) are rolled up and wrapped around the active roller (1) and the passive roller (2) respectively. One end of the active roller (1) is provided with a motor unit (9), which is electrically connected to the control module (10). Under the drive of the control module (10), the motor unit (9) causes the active roller (1) to rotate a set number of times, wrapping the old dustproof film of the unfolding area (41) around the active roller (1), while unwrapping the new dustproof film wrapped on the passive roller (2) and covering the passive reflective target (7).

4. The antifouling treatment method for a passive reflective target according to claim 3, characterized in that: The active roller (1) and the driven roller (2) are located in the housing (3) below the cover plate (5). The cover plate (5) has elongated holes (61) on both sides for the dustproof film to pass through.

5. The antifouling treatment method for the passive reflective target according to claim 3, characterized in that: Two rotating guide rods (6) are installed on both sides of the cover plate (5) or the shell (3). The dustproof film (4) of the unfolded area (41) is supported at both ends by the two rotating guide rods (6) and then wound on the active roller (1) and the driven roller (2).

6. The method for preventing contamination of a passive reflective target according to claim 3, characterized in that: The middle part of the rotating guide rod (6) is a round bar, and the two ends are rotating shaft structures supported on the cover plate (5) or the housing (3); the rotating guide rod (6) is embedded in the elongated hole (61) or installed on the brackets (62) on both sides of the housing (3).

7. The antifouling treatment method for a passive reflective target according to claim 3, characterized in that: The cover plate (5) is equipped with a front panel (8) on the outside, and a gap is provided between the front panel (8) and the cover plate (5) for the dustproof film to pass through; the center of the front panel (8) has a through hole (81) to expose the passive reflective target (7), and a dust-absorbing pad (82) is provided on the outer ring of the back of the front panel (8).

8. The method for preventing contamination of a passive reflective target according to claim 3, characterized in that: The control module includes a control circuit board and a wireless transceiver module (13). The control circuit board is equipped with a microcontroller, which is electrically connected to the wireless transceiver module (13). After the wireless transceiver module (13) receives the membrane replacement signal sent from the remote end, the microcontroller drives the motor unit (9) to rotate according to the set number of revolutions.

9. The method for preventing contamination of a passive reflective target according to claim 3, characterized in that: The control module includes a battery and a control circuit board. The control circuit board is equipped with a microcontroller. The microcontroller drives the motor unit (9) to rotate according to the set number of revolutions after a set time interval.

10. An image displacement measuring instrument, characterized in that: The passive reflective target is described in any one of claims 1 to 9 for antifouling treatment.

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