A water film thickness measuring device based on laser triangulation and a method thereof

Abstract

The application relates to the technical field of measuring devices, and discloses a water film thickness measuring method based on laser triangulation, which comprises the following steps: connecting one end of a water film thickness measuring device to a road inspection vehicle and connecting the other end to a data processing system; irradiating a fine light beam to the surface of a water film by a transmitting system; focusing the reflected light on the upper and lower surfaces of the water film into images on a photoelectric device by an imaging system, and converting the light signals into electric signals; the water film thickness measuring device and method based on laser triangulation; the device can collect image samples to observe clear imaging quality and ideal imaging effect. The oblique laser triangulation method does not require a long transverse distance, the laser can be incident to the water surface at a small angle, the water surface height can be corrected according to the unevenness of the road surface, the measuring difficulty can be effectively reduced, the measuring precision and the measuring work efficiency can be improved.

Description

Technical Field

[0001] This invention relates to the field of measurement equipment technology, specifically to a water film thickness measurement device and method based on laser triangulation. Background Technology

[0002] With the rapid development of the civil aviation industry, the requirements for airport runways are gradually increasing. To ensure airport operational efficiency, runways must be able to meet the needs of aircraft takeoff and landing even under relatively severe weather conditions. Runway condition is crucial to the safe operation of aircraft. In rainy or snowy weather, water easily accumulates on the runway surface, especially during the rainy season and in areas with heavy rainfall in southern my country, where water is difficult to completely drain. This water forms a film on the runway surface. During aircraft takeoff or landing, this film reduces the friction performance of the runway surface, making aircraft tires prone to slippage and loss of directional control during braking, thus affecting the safe operation of the aircraft.

[0003] Existing methods for measuring water film thickness mainly involve manual measurement and sensor measurement. Manual measurement is greatly affected by subjective factors, is labor-intensive, and has low efficiency. Sensor measurement requires installing sensors on the pavement, and the results are affected by the clarity of the water on the pavement, resulting in significant errors. Furthermore, faulty sensors are difficult to repair or replace. Therefore, a more convenient, faster, and more accurate method for measuring water film thickness is needed. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a water film thickness measuring device and method based on laser triangulation, which has the advantages of improving measurement efficiency and accuracy.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for measuring water film thickness based on laser triangulation, characterized in that its steps include:

[0006] The water film thickness measuring device is installed with one end connected to the patrol vehicle and the other end connected to the data processing system;

[0007] A fine beam of light is emitted by the emission system and shines on the surface of the water film. The reflected light from the upper and lower surfaces is focused by the imaging system onto the photoelectric device, and the optical signal is converted into an electrical signal.

[0008] According to the theory of light propagation, the following relationships exist for the propagation of light in different media:

[0009]

[0010] In the formula, a is the angle of incidence of light from medium A to medium B, b is the angle of refraction of light from medium A to medium B, and n is the refractive index.

[0011] Based on the propagation characteristics of light, plot the propagation path of light produced when a laser beam is directed at a water film on the surface of a runway:

[0012]

[0013] According to the fundamental principles of geometry:

[0014]

[0015] From the above formula, the water film thickness h can be obtained as:

[0016]

[0017] In the formula: L is the distance between the incident point and the refraction point, L' is the distance between the reflection point on the water surface and the exit point of the refracted ray from the bottom of the water, a is the reflection angle of the water surface, b is the reflection angle of the ray from the bottom of the water, h is the thickness of the water film, and n is the refractive index.

[0018] The displacement of the light spot on the photodetector, the incident angle, reflection angle and imaging angle of the emitted light are determined by the water film thickness measuring device, and the image distance, object distance and focal length of the receiving lens of the photodetector are determined.

[0019] Based on the propagation characteristics of light, a laser beam is directed at the water film on the runway surface and received by a photodetector. According to the principle of triangle similarity, we can deduce:

[0020]

[0021] The lens imaging formula is as follows:

[0022]

[0023] From the two formulas above, we can derive:

[0024]

[0025] In the formula: x – displacement of the light spot on the photodetector

[0026] y - water film thickness

[0027] γ - Angle of incidence

[0028] α - Reflection angle

[0029] β - Imaging angle

[0030] a - Image distance

[0031] b - object distance

[0032] f - focal length

[0033] The data processing system determines the water film thickness using the oblique laser triangulation method.

[0034] Preferably, the zero point position is first calibrated, and then the water height is determined based on the changes in the water surface and the ground.

[0035] Preferably, the patrol vehicle moves the water film thickness measuring device on the airport runway, and uses a transmission system, imaging system and data processing system to dynamically measure the airport runway and determine the thickness of the water film in each section of the airport runway.

[0036] A water film thickness measuring device based on laser triangulation is used to implement the above-mentioned water film thickness measuring method based on laser triangulation. It includes a main body, a connector for connecting to a patrol vehicle is provided on the back of the main body, a transmitting system, an imaging system and a data processing system are provided inside the main body, and a light-transmitting port is provided at the bottom of the main body. The light-transmitting port is used for the transmitting system and the imaging system to transmit and receive light. The transmitting system, the imaging system and the data processing system are connected by electrical signals.

[0037] Preferably, the emission system includes a laser emitter and a collimating lens, with the collimating lens located in front of the emission port of the laser emitter.

[0038] Preferably, the imaging system includes a receiving lens, a filter, and a photodetector, with the receiving lens and the filter located in front of the optical path of the photodetector, and the filter located between the receiving lens and the photodetector.

[0039] Preferably, the data processing system includes a data processor.

[0040] Beneficial effects:

[0041] This invention relates to a water film thickness measurement device and method based on laser triangulation. The device acquires image samples with clear imaging quality and ideal imaging effects. By employing oblique laser triangulation, a long lateral distance is not required, the laser can be incident on the water surface at a small angle, and the water level can be corrected according to road surface unevenness. Furthermore, it effectively reduces measurement difficulty, improves measurement accuracy, and enhances measurement efficiency. Attached Figure Description

[0042] Figure 1 This is a side view of the connection between the water film thickness measuring device for laser triangulation of the present invention and the road inspection vehicle.

[0043] Figure 2 This is a front view of the connection between the water film thickness measuring device for laser triangulation of the present invention and the road inspection vehicle.

[0044] Figure 3 This is a schematic diagram of the connection of the water film thickness measuring device for laser triangulation according to the present invention;

[0045] Figure 4This is a schematic diagram illustrating the light propagation theory of this invention;

[0046] Figure 5 This is a schematic diagram of the propagation path of the light generated when the laser of the present invention is directed at the water film on the surface of the runway;

[0047] Figure 6 This is a schematic diagram of the oblique laser triangulation method of the present invention;

[0048] Figure 7 This is a schematic diagram illustrating the calibration of the zero-point position of the present invention;

[0049] Figure 8 This is a schematic diagram of image 1 acquired by the first image acquisition system of the present invention;

[0050] Figure 9 This is a schematic diagram of image 2 acquired by the first image acquisition system of the present invention;

[0051] Figure 10 This is a schematic diagram of image 3 acquired by the first image acquisition system of the present invention;

[0052] Figure 11 This is a schematic diagram of image 4 acquired by the first image acquisition system of the present invention;

[0053] Figure 12 This is a schematic diagram of image 5 acquired by the first group of image acquisition systems of the present invention;

[0054] Figure 13 This is a schematic diagram of image 1 acquired by the second image acquisition system of the present invention;

[0055] Figure 14 This is a schematic diagram of image 2 acquired by the second image acquisition system of the present invention;

[0056] Figure 15 This is a schematic diagram of image 3 acquired by the second image acquisition system of the present invention;

[0057] Figure 16 This is a schematic diagram of image 4 acquired by the second image acquisition system of the present invention;

[0058] Figure 17 This is a schematic diagram of image 5 acquired by the second image acquisition system of the present invention.

[0059] In the diagram: 1. Main body; 2. Connector; 3. Laser emitter; 4. Collimating lens; 5. Receiving lens; 6. Filter; 7. Photodetector; 8. Light transmission port. Detailed Implementation

[0060] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0061] Example 1

[0062] Please see Figure 1-3 A water film thickness measuring device based on laser triangulation is used to implement a water film thickness measuring method based on laser triangulation. It includes a main body 1, a connector 2 for connecting to a patrol vehicle is provided on the back of the main body 1, a transmitting system, an imaging system and a data processing system are provided inside the main body 1, and a light-transmitting port 8 is provided at the bottom of the main body 1. The light-transmitting port 8 is used for the transmitting system and the imaging system to transmit and receive light. The transmitting system, the imaging system and the data processing system are connected by electrical signals.

[0063] In this embodiment, the emission system includes a laser emitter 3 and a collimating lens 4, with the collimating lens 4 located in front of the emission port of the laser emitter 3.

[0064] In this embodiment, the imaging system includes a receiving lens 5, a filter 6, and a photodetector 7. The receiving lens 5 and the filter 6 are located in front of the optical path of the photodetector 7, and the filter 6 is located between the receiving lens 5 and the photodetector 7.

[0065] In this embodiment, the data processing system includes a data processor 9.

[0066] Example 2

[0067] Please see Figure 1-7 A method for measuring water film thickness based on laser triangulation, characterized by the following steps:

[0068] The water film thickness measuring device is installed with one end connected to the patrol vehicle and the other end connected to the data processing system;

[0069] A fine beam of light is emitted by the emission system and shines on the surface of the water film. The reflected light from the upper and lower surfaces is focused by the imaging system onto the photoelectric device, and the optical signal is converted into an electrical signal.

[0070] refer to Figure 4 According to the theory of light propagation, the following relationships exist for light propagation in different media:

[0071]

[0072] In the formula, a is the angle of incidence of light from medium A to medium B, b is the angle of refraction of light from medium A to medium B, and n is the refractive index.

[0073] refer to Figure 5 Based on the propagation characteristics of light, plot the propagation path of light produced when a laser beam is directed at a water film on the surface of a runway:

[0074]

[0075] According to the fundamental principles of geometry:

[0076]

[0077] From the above formula, the water film thickness h can be obtained as:

[0078]

[0079] In the formula: L is the distance between the incident point and the refraction point, L' is the distance between the reflection point on the water surface and the exit point of the refracted ray from the bottom of the water, a is the reflection angle of the water surface, b is the reflection angle of the ray from the bottom of the water, h is the thickness of the water film, and n is the refractive index.

[0080] The displacement of the light spot on the photodetector, the incident angle, reflection angle and imaging angle of the emitted light are determined by the water film thickness measuring device, and the image distance, object distance and focal length of the receiving lens of the photodetector are determined.

[0081] refer to Figure 6 Based on the propagation characteristics of light, a laser beam is directed at the water film on the runway surface and received by a photodetector. According to the principle of triangle similarity, we can deduce:

[0082]

[0083] The lens imaging formula is as follows:

[0084]

[0085] From the two formulas above, we can derive:

[0086]

[0087] In the formula: x – displacement of the light spot on the photodetector

[0088] y - water film thickness

[0089] γ - Angle of incidence

[0090] α - Reflection angle

[0091] β - Imaging angle

[0092] a - Image distance

[0093] b - object distance

[0094] f - focal length

[0095] The data processing system determines the water film thickness using the oblique laser triangulation method.

[0096] refer to Figure 7 In this embodiment, the zero point position is first calibrated, and then the water level is determined based on the changes in the water surface and the changes in the ground.

[0097] Image samples were acquired using a water film thickness measurement device based on laser triangulation according to Embodiment 1, and measurements were performed according to the method of Embodiment 2. The oblique laser triangulation method does not require a long lateral distance, the laser can be incident on the water surface at a small angle, and the water level can be corrected according to the unevenness of the road surface.

[0098] Two sets of images are acquired using two image acquisition systems. The first set of image acquisition systems acquires a reference image. Figure 8-12 The second group of image acquisition systems acquires reference images. Figure 13-17 ;

[0099] The first and second image acquisition systems acquired 5 images and their pixel counts, as shown in Table 1-2. The acquisition results are shown in Table 3-4.

[0100]

[0101] Table 1

[0102]

[0103] Table 2

[0104] Distance of the change in the reflection point First group of image acquisition systems Second image acquisition system x1 2.24 4.24 X2 10.00 4.12 X3 8.06 7.81 X4 8.54 5.66

[0105] Table 3

[0106] Distance of change of reflection point First group of image acquisition systems Second image acquisition system y1 3.87 6.32 y2 13.42 9.22 y3 18.36 13.04 y4 19.70 14.87

[0107] Table 4

[0108] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for measuring water film thickness based on laser triangulation, characterized in that, The steps include: The water film thickness measuring device is installed with one end connected to the patrol vehicle and the other end connected to the data processing system; A fine beam of light is emitted by the emission system and shines on the surface of the water film. The reflected light from the upper and lower surfaces is focused by the imaging system onto the photoelectric device, and the optical signal is converted into an electrical signal. The displacement of the light spot on the photodetector, the incident angle, reflection angle and imaging angle of the emitted light are determined by the water film thickness measuring device, and the image distance, object distance and focal length of the receiving lens of the photodetector are determined. Based on the propagation characteristics of light, a laser beam is directed at the water film on the runway surface and received by a photodetector. According to the principle of triangle similarity, we can deduce: The lens imaging formula is as follows: From the two formulas above, we can derive: In the formula: x – displacement of the light spot on the photodetector y - water film thickness γ - Angle of incidence α - Reflection angle β - Imaging angle a - Image distance b - object distance f - focal length The data processing system determines the water film thickness using the oblique laser triangulation method.

2. The water film thickness measurement method based on laser triangulation according to claim 1, characterized in that: First, the zero point position is calibrated, and then the water level is determined based on the changes in the water surface and the ground surface.

3. The water film thickness measurement method based on laser triangulation according to claim 1, characterized in that: The patrol vehicle moves the water film thickness measuring device on the airport runway, and uses a launch system, imaging system and data processing system to dynamically measure the airport runway and determine the thickness of the water film in each section of the airport runway.

4. A water film thickness measuring device based on laser triangulation, used to implement the water film thickness measuring method based on laser triangulation as described in any one of claims 1-3, characterized in that: Includes a main body (1), with a connector (2) for connecting to the patrol vehicle on the back of the main body (1), and a transmission system, an imaging system and a data processing system inside the main body (1). A light-transmitting port (8) is opened at the bottom of the main body (1), which is used for the transmission system and the imaging system to transmit and receive light. The transmission system, the imaging system and the data processing system are connected by electrical signals.

5. The water film thickness measuring device based on laser triangulation according to claim 4, characterized in that: The emission system includes a laser emitter (3) and a collimating lens (4), with the collimating lens (4) located in front of the emission port of the laser emitter (3).

6. The water film thickness measuring device based on laser triangulation according to claim 4, characterized in that: The imaging system includes a receiving lens (5), a filter (6), and a photodetector (7). The receiving lens (5) and the filter (6) are located in front of the optical path of the photodetector (7), and the filter (6) is located between the receiving lens (5) and the photodetector (7).

7. The water film thickness measuring device based on laser triangulation according to claim 4, characterized in that: The data processing system includes a data processor (9).

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