Multi-beam parallelism calibration device and method

Abstract

The invention discloses a multi-beam parallelism calibration device and method, and belongs to the technical field of laser ranging, the multi-beam parallelism calibration device comprises three laser ranging and adjusting modules, an L-shaped adapter plate a, a ground glass screen, an angle gauge, a bottom plate a and a precise parallel guide rail of a calibration part, and a CCD camera, a bottom plate b, a signal transmission cable and an upper computer of a signal receiving and processing part; a calibration device is adopted to emit three light sources to the frosted glass screen, the positions of three light spots on the frosted glass screen are determined through an image analysis method, and if the positions of the light spots are kept unchanged when the frosted glass screen is located at different positions of the guide rail, it is considered that light beams emitted by the three laser range finders are parallel to one another; and if the position of the light spot changes before and after the frosted glass screen moves, readjusting until the position of the light spot remains unchanged before and after the frosted glass screen moves. According to the invention, whether the light beams are parallel to each other can be rapidly evaluated, the parallelism between the light beams adjusted by the device is high, and the control plane angle measurement precision is greatly improved.

Description

Technical Field

[0001] The present invention relates to the field of laser measurement, and particularly to a multi-beam parallelism calibration device and method. Background Art

[0002] In the field of aircraft assembly and manufacturing, it is necessary to calibrate and measure the control of the aircraft rudder surface angle to ensure the control of the aircraft's attitude during flight. With the increasingly wide application of composite materials, special coatings, etc. on the aircraft surface, it has become an inevitable trend to calibrate the aircraft rudder surface control system in a high-precision and non-contact manner.

[0003] Currently, the method of using the multi-beam ranging method to measure the rudder surface angle utilizes the principle that three points determine a plane. Three laser rangefinders are placed on a plane, and by measuring the distances from the three laser rangefinders to the rudder surface to be measured, the angle difference change between the plane where the laser rangefinders are located and the rudder surface to be measured can be calculated. However, if the emitted beams of the rangefinders are not strictly parallel, the measured change in the rudder surface angle will deviate from the actual rudder surface deflection angle, and the accuracy requirements for rudder surface angle measurement cannot be met.

[0004] In the prior art, patent CN116400514A discloses a parallel light debugging device and method for a high-precision optical system. The light source forms a first light spot on the reference screen at the first position through the optical module. The light spot acquisition system obtains the first light spot diameter through the first light spot. At the same time, the light spot acquisition system and the reference screen are moved while keeping their relative positions unchanged. The light source forms a second light spot on the reference screen at the second position through the optical module. The light spot acquisition system obtains the second light spot diameter through the second light spot. The light spot acquisition system compares the difference value between the first light spot diameter and the second light spot diameter, and obtains the information on whether the emitted beams of the high-precision optical system are parallel according to the difference value. This method only judges whether the beams emitted by a single light source are parallel, so as to judge the quality of the light source emitted beams, and cannot judge whether the beams emitted between multiple light sources are parallel to each other. Summary of the Invention

[0005] The present invention aims to solve the measurement error problem existing in the prior art of laser measurement of aircraft rudder surface deflection, and proposes a multi-beam parallelism calibration device and method. Using this device and method, the parallelism between the beams emitted by multiple laser light sources can be quickly calibrated.

[0006] To achieve the above-mentioned invention purpose, the technical solution of the present invention is as follows:

[0007] A multi-beam parallelism calibration device, characterized by comprising: a calibration part and a signal transmission and processing part; the calibration part includes three laser ranging and adjustment modules, an L-shaped adapter plate a, a ground glass screen, a protractor, a base plate a and a precision parallel guide rail; each laser ranging and adjustment module is installed on the L-shaped adapter plate a, and the L-shaped adapter plate a is fixedly connected to the precision parallel guide rail; the ground glass screen is fixed on the protractor and rotates synchronously with the protractor, the protractor is fixed on the base plate a, and the base plate a is slidably connected to the precision parallel guide rail; the signal receiving and processing part includes a CCD camera, a base plate b, a signal transmission cable and a host computer, the CCD camera is fixed on the base plate b, and the base plate b is fixed on the precision parallel guide rail; the CCD camera is connected to one end of the signal transmission cable, and the other end of the signal transmission cable is connected to the host computer, and the CCD camera transmits the captured image to the host computer through the signal transmission cable.

[0008] Further, the laser ranging and adjustment module includes a laser rangefinder, a two-dimensional adjustment frame and an L-shaped adapter plate b; the laser rangefinder is fixed on the adjustment surface of the two-dimensional adjustment frame to adjust the emission angle of the laser, the two-dimensional adjustment frame is fixed on the L-shaped adapter plate b, and the L-shaped adapter plate b is fixed on the L-shaped adapter plate a.

[0009] Further, four dark square marks are painted at the four corners of the ground glass screen for positioning the positions of the light spots on the ground glass screen.

[0010] A multi-beam parallelism calibration method, based on the above multi-beam parallelism calibration device, is characterized by including the following steps:

[0011] Align the side of the ground glass screen with the 0° direction of the protractor and lock it. The 0° direction of the protractor is parallel to the precision parallel guide rail. At this time, the side of the ground glass screen is parallel to the direction of the precision parallel guide rail;

[0012] Rotate the protractor to 90°. At this time, the ground glass screen is perpendicular to the direction of the precision parallel guide rail; move the ground glass screen along the precision parallel guide rail to the left side near the laser ranging and adjustment module, and turn on the light sources of the three laser rangefinders. The lights emitted by the three light sources form three light spots arranged in a triangle on the ground glass screen;

[0013] The CCD camera collects the image of the ground glass screen, and determines the positions of the three light spots on the ground glass screen through an image analysis method; then move the ground glass screen along the precision parallel guide rail to the end far from the laser ranging and adjustment module, and collect the ground glass screen image through the CCD camera and determine the light spot positions;

[0014] If the position of the light spot remains unchanged when the ground glass screen is at different positions on the guide rail, it is considered that the beams emitted by the three laser rangefinders are parallel to each other; if the position of the light spot changes before and after the ground glass screen moves, it is necessary to adjust the adjustment frame in the laser ranging and adjustment module to adjust the direction of the beam emitted by the laser rangefinder until the position of the light spot remains unchanged before and after the ground glass screen moves.

[0015] Further, the method for determining the positions of the three light spots on the ground glass screen by image analysis includes:

[0016] Read the grayscale image of the ground glass screen obtained by the CCD to obtain the grayscale matrix S;

[0017] Scan the grayscale matrix S column by column to obtain the maximum value of each column, and set a threshold a. If the maximum value of this column is greater than the threshold a, it is considered that the light spot covers this column, and record the column number;

[0018] Take the middle value of the continuous interval where the column numbers covered by the three light spots are located, and record the row numbers where the grayscale values of these three columns in the grayscale matrix S are greater than the threshold a; accordingly, obtain the four vertex coordinates of the rectangular area where the three light spots are located respectively;

[0019] To prevent the actual light spot range from exceeding the rectangular area, expand the range of the rectangular area, and recalculate the position of the light spot in the expanded area;

[0020] Obtain the positions of the four dark square marks on the ground glass screen in the same way, establish a reference coordinate system with the positions of the dark squares as the reference coordinates, and calculate the position of the light spot in this reference coordinate system.

[0021] Further, the following method is used to expand the range of the rectangular area where the three light spots are located: for the vertex coordinates on the side close to the origin, reduce 10% of the corresponding side length and round it, and for the vertex coordinates on the side far from the origin, increase 10% of the corresponding side length and round it.

[0022] Further, the following formula is used to recalculate the position of the light spot in the expanded area:

[0023]

[0024] In the formula, n1 is the number of pixels with grayscale values greater than the threshold a in the expanded rectangular area, and are the coordinates of the pixel point, is the grayscale of the pixel point.

[0025] Further, the positions of each light spot in the reference coordinate system established with the positions of the four dark squares as the reference coordinates are respectively:

[0026] Light spot 1:

[0027]

[0028] Light spot 2:

[0029]

[0030] Light spot 3:

[0031]

[0032] Wherein, k is the spacing between adjacent dark squares, are the positions of the three light spots calculated in the enlarged rectangular area, are the positions of the four dark squares calculated by the same method.

[0033] Further, whether the position of the light spot changes before and after the frosted glass screen moves is judged according to the following method: Move the frosted glass screen, recalculate the positions of the three light spots in the same way, calculate the position deviation of the light spot before and after the movement. When the deviation is less than 0.01k, it is considered that the position of the light spot remains the same before and after the frosted glass screen moves.

[0034] Further, if the position of the light spot is inconsistent before and after the frosted glass screen moves, the adjustment method is as follows:

[0035] Taking a beam of light as an example, if the light spots A and A' before and after adjusting the frosted glass screen do not coincide, then fine-tune the position of the light spot in the direction; after adjustment, move the frosted glass screen back to the left side of the guide rail close to the laser ranging and adjustment module group along the precision parallel guide rail, calculate the position deviation of the light spot before and after the frosted glass screen moves. If the position of the light spot remains the same before and after the movement, stop the adjustment; if there is still a deviation in the position of the light spot before and after the movement, repeat the above process until the position of the light spot is the same before and after the frosted glass screen moves. At this time, this beam of light is parallel to the direction of the parallel guide rail; similarly, the remaining beams of light are adjusted according to the same process to make each beam of light parallel to the direction of the parallel guide rail, then these beams of light are parallel to each other.

[0036] In summary, the present invention has the following advantages:

[0037] (1) The present invention designs a multi-beam parallel adjustment device, which uses a CCD camera to obtain the position of the light spot at the cross-section of the light beam on the frosted glass screen, can quickly evaluate whether the light beams are parallel to each other, and the parallelism between the light beams adjusted by using this device is high, and the corresponding measurement accuracy of the rudder surface angle is also greatly improved.

[0038] (2) The present invention can quickly calibrate the parallelism between the light beams emitted by multiple laser light sources; by using the method of CCD image analysis, it can automatically obtain the position of the laser beam hitting the light screen, judge whether multiple laser beams are parallel, and provide the direction of beam calibration. Brief Description of the Drawings

[0039] Figure 1 It is a structural diagram of the multi-beam parallel adjustment device of the present invention;

[0040] Figure 2 It is a grayscale image of the ground glass screen and spot zoning;

[0041] Figure 3 It is the calculation of the coordinates of the dark square and the spot;

[0042] Figure 4 It is a schematic diagram of the method for adjusting the beam parallelism;

[0043] In the figure:

[0044] 1 - Laser ranging and adjustment module; 2 - L-shaped adapter plate a; 3 - Ground glass screen; 4 - Angle gauge; 5 - Base plate a; 6 - Precision parallel guide rail; 7 - Laser rangefinder; 8 - Two-dimensional adjustment bracket; 9 - L-shaped adapter plate b; 10 - CCD camera; 11 - Base plate b; 12 - Signal transmission cable; 13 - Host computer; 14 - Spot; 15 - Dark square mark. Detailed Description of the Preferred Embodiments

[0045] To more clearly illustrate the present invention, the present invention will be further described below in conjunction with the preferred embodiments and the drawings. Those skilled in the art should understand that the specific content described below is illustrative rather than restrictive, and should not be used to limit the protection scope of the present invention.

[0046] Embodiment 1

[0047] The present invention provides a multi-beam parallelism calibration device, as Figure 1 shown, including a calibration part and a signal transmission and processing part.

[0048] The calibration part includes three laser ranging and adjustment modules 1, L-shaped adapter plate a 2, ground glass screen 3, angle gauge 4, base plate a 5 and precision parallel guide rail 6.

[0049] Among them, the laser ranging and adjustment module is composed of a laser rangefinder 7, a two-dimensional adjustment bracket 8, and an L-shaped adapter plate b 9. The laser rangefinder 7 is fixed on the adjustment surface of the two-dimensional adjustment bracket 8 to adjust the emission angle of the laser. The two-dimensional adjustment bracket 8 is then fixed on the L-shaped adapter plate b 9 to form the laser ranging and adjustment module. Each laser ranging and adjustment module is fixed on the L-shaped adapter plate a 2 through the L-shaped adapter plate b 9. The L-shaped adapter plate a 2 is stuck in the precision parallel guide rail 6 through the bottom slot and fixed by bolts.

[0050] The ground glass screen 3 is fixed on the angle gauge 4 and rotates synchronously with the angle gauge 4. The angle gauge 4 is fixed on the bottom plate a5 by bolts. The bottom of the bottom plate a5 has a matching groove that is stuck on the precision parallel guide rail 6 and can slide along the direction of the parallel guide rail.

[0051] Furthermore, four dark square marks are painted at the four corners of the ground glass screen 3 for positioning the position of the light spot on the ground glass screen.

[0052] The signal receiving and processing part consists of a CCD camera 10, a bottom plate b11, a signal transmission cable 12, and a host computer 13. The CCD camera is fixed on the bottom plate b11 by studs. The bottom plate b is stuck on the precision parallel guide rail 6 through the slot at the bottom and fixed by bolts. One end of the signal transmission cable is connected to the CCD camera, and the other end of the signal transmission cable is connected to the host computer. The CCD camera transmits the captured image to the host computer through the signal transmission cable.

[0053] Embodiment 2

[0054] Based on the multi-beam parallelism calibration device proposed in the above Embodiment 1, this embodiment proposes a multi-beam parallelism calibration method, including the following steps:

[0055] Align the side of the ground glass screen 3 with the zero-degree direction of the angle gauge 4 and lock it. The 0° direction of the angle gauge 4 is parallel to the slot of the bottom precision parallel guide rail 6. At this time, the side of the ground glass screen 3 is parallel to the direction of the precision parallel guide rail 6.

[0056] Rotate the angle gauge 4 to 90°. At this time, the ground glass screen 3 is perpendicular to the direction of the precision parallel guide rail 6. Move the ground glass screen 3 along the precision parallel guide rail 6 to the left side of the guide rail close to the laser ranging and adjustment module 1. Turn on the light sources of the three laser rangefinders 7. The light emitted by the three light sources forms three light spots 14 arranged in a triangle on the ground glass screen 3.

[0057] The CCD camera 10 collects the image of the ground glass screen 3, and determines the positions of the three light spots 14 on the ground glass screen 3 through the image analysis method. Move the ground glass screen 3 along the precision parallel guide rail 6 to the end of the guide rail far from the laser ranging and adjustment module 1. Collect the image of the ground glass screen 3 through the CCD camera 10 and determine the position of the light spot 14. When the position of the light spot 14 remains unchanged when the ground glass screen 3 is in different positions of the guide rail, it is considered that the beams emitted by the three laser rangefinders 7 are parallel to each other; if the position of the light spot 14 changes before and after the movement of the ground glass screen 3, the adjustment frame in the laser ranging and adjustment module 1 needs to be adjusted to adjust the direction of the light beam emitted by the laser rangefinder 7 until the position of the light spot 14 remains unchanged before and after the movement of the ground glass screen 3.

[0058] Furthermore, the image analysis method used in the present invention is as follows:

[0059] The grayscale image of the ground glass screen obtained by the CCD is as follows Figure 2 As shown, there are a total of three light spots 14 and four dark square markers 15 for position correction. Read the grayscale image to obtain the grayscale matrix S, and scan each column to obtain the maximum value of each column. Set the threshold a according to the actual usage requirements. If the maximum value of a column is greater than the threshold a, it is considered that there is a bright area in this column. Within the range covered by the light spot, record the column number to determine the position of the light spot.

[0060] According to the equilateral triangle arrangement of the laser ranging modules, the column numbers covered by the light spots should be three consecutive intervals, namely n1~n2, p1~p2, q1~q2. It should be noted that the method for calculating the position of the light spot in the present invention takes the case where the light spots are arranged in a triangle as an example, but is not limited to the triangular arrangement, and is also applicable to the case where the light spots are arranged in a straight line. When the special case where the light spots are arranged in a vertical straight line occurs, the initial grayscale matrix needs to be transposed to facilitate distinguishing different light spots in the vertical direction. After obtaining the position result of the light spot, exchange the horizontal and vertical coordinates of the light spot as the final result.

[0061] Take the median values of the three intervals Record the row numbers in the grayscale matrix where the grayscale values of these three columns are greater than the threshold a, which should be three consecutive intervals, namely n3~n4, p3~p4, q3~q4. Then the three light spots are within the following rectangular areas, and each area is represented by the four vertex coordinates of the rectangular area.

[0062] Area 1: (n1, n3), (n1, n4), (n2, n3), (n2, n4);

[0063] Area 2: (p1, p3), (p1, p4), (p2, p3), (p2, p4);

[0064] Area 3: (q1, q3), (q1, q4), (q2, q3), (q2, q4).

[0065] To prevent the actual light spot range from exceeding the area, taking Area 1 as an example, reduce n1 and n3 by 10% of the corresponding side length and round down, and increase n2 and n4 by 10% of the corresponding side length and round up to expand the area range:

[0066] Area 1:

[0067] Similarly, expand Area 2 and Area 3:

[0068] Area 2:

[0069] Area 3:

[0070] Calculate the position of the light spot in the enlarged area. Taking the light spot in area 1 as an example, search for the coordinates of all gray values greater than the threshold a in area 1 The corresponding gray values are respectively n1 is the number of pixels with gray values greater than the threshold a in area 1, and the coordinate position is calculated as:

[0071]

[0072] Calculate the positions of the light spots in area 2 and area 3 in the same way:

[0073]

[0074] Similarly, calculate the positions of the four dark squares on the ground glass screen in the same way. Set the threshold b, search for and calculate the positions of the four dark squares with gray values less than b.

[0075] The calculated positions of the three light spots are The calculated positions of the dark squares are Such as Figure 3 As shown. Taking the positions of the dark squares as the reference coordinates, the spacing of the dark squares is known, set as k, establish a reference coordinate system, and calculate the positions of the light spots in the reference coordinate system as:

[0076] Light spot 1:

[0077]

[0078] Light spot 2:

[0079]

[0080] Light spot 3:

[0081]

[0082] The coordinates of light spot 1, light spot 2, and light spot 3 in the reference coordinate system are briefly recorded as: (x1, y1), (x2, y2), (x3, y3). Move the ground glass screen, and calculate the positions of the three light spots in the same way as: (x1’, y1’), (x2’, y2’), (x3’, y3’), and calculate the position deviation of the light spots before and after the movement:

[0083]

[0084] When Δr1, Δr2, and Δr3 are all less than 0.01k, it is considered that the positions of the light spots remain the same before and after the movement of the ground glass screen.

[0085] The adjustment method of the present invention for the inconsistent positions of the light spots before and after the movement of the ground glass screen is as follows:

[0086] As Figure 4 shown, taking a beam of light as an example, the light is emitted by a laser rangefinder. When the ground glass screen is at the left side of the guide rail near the laser ranging and adjustment module, a light spot A is formed; the ground glass screen is moved along the precision parallel guide rail to the end of the guide rail far from the laser ranging and adjustment module, and a light spot A' is formed on the ground glass screen by the light beam. If the light spots A and A' do not coincide, the position of the light spot is finely adjusted in the direction. For example, if A' is at the upper right of A, the light spot is finely adjusted towards the lower left. After adjustment, the ground glass screen is moved back along the precision parallel guide rail to the left side of the guide rail near the laser ranging and adjustment module, and the deviation of the light spot position before and after the movement of the ground glass screen is calculated. If the light spot positions before and after the movement remain the same, the adjustment is stopped; if there is still a deviation in the light spot positions before and after the movement, the above process is repeated until the light spot positions before and after the movement of the ground glass screen are the same. At this time, this light beam is parallel to the direction of the parallel guide rail.

[0087] Similarly, the same adjustment process is carried out for several other light beams to make each light beam parallel to the direction of the parallel guide rail, and then these light beams are parallel to each other.

[0088] The above is only a preferred embodiment of the present invention, and does not impose any formal restrictions on the present invention. Any simple modification or equivalent change made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A multi-beam parallelism calibration device, characterized in that: include: Calibration part and signal transmission and processing part; The calibration part comprises three laser distance measuring and adjustment modules (1), an L-shaped adapter plate a (2), a frosted glass screen (3), an inclinometer (4), a bottom plate a (5) and a precision parallel guide rail (6); each laser distance measuring and adjustment module (1) is mounted on the L-shaped adapter plate a (2), the L-shaped adapter plate a (2) is fixedly connected to the precision parallel guide rail (6); the frosted glass screen (3) is fixed on the inclinometer (4) and rotates synchronously with the inclinometer (4), the inclinometer (4) is fixed on the bottom plate a (5), and the bottom plate a (5) is slidably connected to the precision parallel guide rail (6). The invention relates to a precision parallel guide rail (6); the signal receiving and processing part comprises a CCD camera (10), a base plate b (11), a signal transmission cable (12) and a host computer (13); the CCD camera (10) is fixed on the base plate b (11), and the base plate b (11) is fixed on the precision parallel guide rail (6); the CCD camera (10) is connected to one end of the signal transmission cable (12), and the other end of the signal transmission cable (12) is connected to the host computer (13); the CCD camera (10) transmits the captured image to the host computer through the signal transmission cable (12).

2. A multi-beam parallelism calibration device as claimed in claim 1, characterized in that: The laser distance measurement and adjustment module (1) comprises a laser distance meter (7), a two-dimensional adjustment frame (8) and an L-shaped adapter plate b (9); the laser distance meter (7) is fixed on an adjustment surface of the two-dimensional adjustment frame (8) to adjust the emission angle of the laser, the two-dimensional adjustment frame (8) is fixed on the L-shaped adapter plate b (9), and the L-shaped adapter plate b (9) is fixed on the L-shaped adapter plate a (2).

3. A multi-beam parallelism calibration device as claimed in claim 1, characterized in that: Four dark square marks at fixed positions are applied at the four corners of the frosted glass screen (3) to locate the position of the light spot (14) on the frosted glass screen (3).

4. A multi-beam parallelism calibration method, based on a multi-beam parallelism calibration device according to any one of claims 1 to 3, characterized in that: The steps include: Align the side of the frosted glass screen (3) with the 0° direction of the inclinometer (4) and lock them, so that the 0° direction of the inclinometer (4) is parallel to the precision parallel guide rail (6). At this time, the side of the frosted glass screen (3) is parallel to the direction of the precision parallel guide rail (6); The angle meter (4) is rotated to 90 degrees, at which time the frosted glass screen (3) is perpendicular to the direction of the precision parallel guide rail (6); the frosted glass screen (3) is moved along the precision parallel guide rail (6) to the left side of the guide rail close to the laser distance measurement and adjustment module (1), and the light sources of the three laser distance meters (7) are turned on. The light emitted by the three light sources appears as three light spots (14) arranged in a triangle on the frosted glass screen (3); The CCD camera (10) collects an image of the frosted glass screen (3), and determines the positions of three light spots (14) on the frosted glass screen (3) by means of an image analysis method; the frosted glass screen (3) is then moved along the precision parallel guide rail (6) to an end of the guide rail away from the laser distance measurement and adjustment module (1), and the CCD camera (10) collects an image of the frosted glass screen (3) and determines the positions of the light spots (14); If the position of the light spot (14) remains unchanged when the frosted glass screen (3) is at different positions on the guide rail, it is considered that the light beams emitted by the three laser rangefinders (7) are parallel to each other; if the position of the light spot (14) changes before and after the frosted glass screen (3) moves, it is necessary to adjust the adjustment frame in the laser distance measurement and adjustment module (1) to adjust the direction of the light beam emitted by the laser rangefinder (7) until the position of the light spot (14) remains unchanged before and after the frosted glass screen (3) moves.

5. A multi-beam parallelism calibration method as claimed in claim 4, characterized in that: The method of determining the positions of the three light spots on the frosted glass screen by using an image analysis method includes: Read the grayscale image of the frosted glass screen acquired by the CCD to obtain the grayscale matrix S; Scan the gray matrix S by column to obtain the maximum value of each column, and set a threshold a. If the maximum value of the column is greater than the threshold a, it is considered that the light spot covers the column, and the column number is recorded; Take the middle value of the continuous interval of the column numbers covered by the three light spots, and record the row numbers of the grayscale matrix S in these three columns whose grayscale values ​​are greater than the threshold a; based on this, obtain the coordinates of the four vertices of the rectangular area where the three light spots are located; In order to prevent the actual light spot range from exceeding the rectangular area, the range of the rectangular area is expanded, and the position of the light spot is recalculated in the expanded area; The positions of the four dark square marks on the frosted glass screen are obtained in the same way. The positions of the dark squares are used as reference coordinates to establish a reference coordinate system, and the position of the light spot in the reference coordinate system is calculated.

6. A multi-beam parallelism calibration method as claimed in claim 5, characterized in that: The following method is used to expand the rectangular area where the three light spots are located: for the vertex coordinates close to the origin, the corresponding side length is reduced by 10% and rounded up; for the vertex coordinates far from the origin, the corresponding side length is increased by 10% and rounded up.

7. A multi-beam parallelism calibration method as claimed in claim 5, characterized in that: The position of the light spot is recalculated in the enlarged area using the following formula: Where n1 is the number of pixels in the expanded rectangular area whose grayscale value is greater than the threshold a. and is the coordinate of the pixel point, is the grayscale of the pixel.

8. A multi-beam parallelism calibration method as claimed in claim 5, characterized in that: The positions of each light spot in the reference coordinate system established with the positions of the four dark squares as reference coordinates are: Spot 1: Light spot 2: Light spot 3: Where k is the distance between adjacent dark blocks, are the positions of the three light spots calculated in the expanded rectangular area, are the positions of the four dark squares calculated using the same method.

9. A multi-beam parallelism calibration method as claimed in claim 1, characterized in that: Whether the position of the light spot changes before and after the frosted glass screen moves is determined by the following method: move the frosted glass screen, recalculate the positions of the three light spots in the same way, calculate the position deviation of the light spot before and after the movement, and when the deviation is less than 0.01k, it is considered that the position of the light spot remains consistent before and after the frosted glass screen moves.

10. A multi-beam parallelism calibration method according to claim 1 or 9, characterized in that: If the light spot position is inconsistent before and after the frosted glass screen moves, the adjustment method is as follows: Take a beam of light as an example. If the light spots A and A' do not overlap before and after adjusting the frosted glass screen, adjust the light spot position to Fine-tune the direction; after adjustment, move the frosted glass screen along the precision parallel guide rail back to the left side of the guide rail near the laser ranging and adjustment module group, calculate the deviation of the light spot before and after the movement of the frosted glass screen, if the light spot position before and after the movement is consistent, stop adjusting; if there is still a deviation in the light spot position before and after the movement, repeat the above process until the light spot is consistent before and after the movement of the frosted glass screen, at this time the light beam is parallel to the direction of the parallel guide rail; similarly, adjust the remaining light beams according to the same process to make each light beam parallel to the direction of the parallel guide rail, then these light beams are parallel to each other.

Images