Laser scanning method and device based on two-dimensional angular displacement table interpolation

Abstract

The invention belongs to the technical field of three-dimensional measurement, and relates to a laser scanning method based on two-dimensional angular displacement table interpolation, and the method comprises the steps: employing a two-dimensional angular displacement table to drive a laser detection interpolation module to rotationally scan a to-be-measured object, so as to obtain initial point cloud data; on the basis of the maximum spacing of the laser scanning beam and the actual scanning demand spacing of the object to be detected, the interpolation times of the initial point cloud data are determined, and the rotation angle of a laser detection interpolation module is determined according to the interpolation times; and driving the laser detection interpolation module to sequentially rotate according to the rotation angles by using the two-dimensional angular displacement table, and performing interpolation scanning at each rotation angle to obtain encrypted point cloud data. According to the invention, the engineering scanning precision and the field measurement speed can be improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of three-dimensional measurement, and more particularly, relates to a laser scanning method and device based on two-dimensional angular displacement table interpolation. BACKGROUND

[0002] In tunnel and slope construction, spatial data needs to be obtained through measurement technology to provide key support for engineering design, construction monitoring and safety evaluation. However, due to the actual problems that the main size and topography error of the tunnel and slope are difficult to measure, there is a lack of rapid and intuitive detection means, which makes it difficult to perform accurate construction for wet spraying operation, excavator operation and other operations, thereby often requiring repeated rework, causing waste of personnel and materials. The construction quality is severely dependent on personnel quality, with great volatility.

[0003] Currently, the mature civil engineering rapid scanning instruments on the market mainly include two mainstream products: high-precision modeling equipment and portable rapid scanning equipment. High-precision equipment, such as Leica RTC360 and FARO Focus, has excellent point cloud scanning precision, but the detection time is long, and the data needs to be processed offline, which cannot directly guide the operation on the construction site; portable equipment, such as digital green soil LiBackpack DG50, has the characteristics of light and fast scanning, but the measurement accuracy is ±10cm, and the anti-interference ability is poor, which cannot meet the operation requirements with a detection accuracy of ±2cm. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a laser scanning method and device based on two-dimensional angular displacement table interpolation, aiming to solve the problems of low scanning efficiency, poor anti-interference ability and low scanning precision of the existing civil engineering rapid scanning technology.

[0005] To achieve the above-mentioned purpose, in a first aspect, the present application provides a laser scanning method based on two-dimensional angular displacement table interpolation, comprising: S1 driving a laser detection interpolation module to rotate and scan a to-be-measured object to obtain preliminary point cloud data by using a two-dimensional angular displacement platform; S2 determining the number of interpolations of the preliminary point cloud data based on the maximum distance of the laser scanning line bundle and the actual scanning requirement distance of the to-be-measured object, and determining the rotation angle of the laser detection interpolation module according to the number of interpolations; S3 driving the laser detection interpolation module to rotate in turn according to the rotation angle by using the two-dimensional angular displacement platform, and performing interpolation scanning at each rotation angle to obtain encrypted point cloud data.

[0006] Further, after step S3, the encrypted point cloud data is also used to obtain the underbreak data cloud map or overbreak data cloud map of the to-be-measured object.

[0007] Further, the interval between adjacent point clouds in the encrypted point cloud data is less than the actual scanning requirement interval.

[0008] In a second aspect, the application provides a laser scanning device for implementing the aforementioned laser scanning method, comprising an electric control module and a laser detection interpolation module, and a data processing and display module and a two-dimensional angular displacement table connected with the electric control module respectively: The electric control module is used to control the two-dimensional angular displacement table to drive the laser detection interpolation module to rotate and scan the object to be measured, so as to obtain preliminary point cloud data; The data processing and display module is used to determine the interpolation times of the preliminary point cloud data based on the maximum interval of the laser scanning line bundle and the actual scanning requirement interval of the object to be measured, and determine the rotation angle of the laser detection interpolation module according to the interpolation times; The electric control module is also used to control the two-dimensional angular displacement table to drive the laser detection interpolation module to rotate in turn according to the rotation angle, and perform interpolation scanning at each rotation angle, so as to obtain encrypted point cloud data.

[0009] Further, the laser detection interpolation module comprises a laser radar unit, the laser radar unit is arranged on the two-dimensional angular displacement table, and the laser radar unit can rotate around the X axis, and the two-dimensional angular displacement table can drive the laser radar unit to rotate around the Y axis and / or the Z axis.

[0010] Further, the two-dimensional angular displacement table comprises a radar support, a Y-axis angular displacement unit, a Z-axis angular displacement unit and an inclination sensor connected in turn, the laser radar unit is fixed on the radar support; the inclination sensor is connected with the data processing and display module, and is used to detect and obtain the attitude data of the laser scanning device and transmit the attitude data to the data processing and display module; the electric control module can control the Y-axis angular displacement unit and / or the Z-axis angular displacement unit to rotate based on the attitude data.

[0011] Further, the rotation accuracy of the two-dimensional angular displacement table is better than 0.14°, and the repeat positioning accuracy is not greater than 0.005°.

[0012] Further, the data processing and display module comprises a data processing unit and a data display unit connected with each other, the data processing unit is used to obtain the underbreak data cloud picture or overbreak data cloud picture of the object to be measured by using the encrypted point cloud data, and the data display unit is used to display the underbreak data cloud picture or overbreak data cloud picture.

[0013] Further, the electric control module is arranged in the shell, the data processing and display module and the laser detection and interpolation module are arranged on a pair of side walls of the shell, and the data processing and display module is located in the shell with a data display end thereof facing outside the shell, and the laser detection and interpolation module is located outside the shell; and the protective shell is arranged outside the laser detection and interpolation module and connected with the shell.

[0014] It can be understood that the beneficial effects of the second aspect described above can be referred to the related description in the first aspect described above, which will not be repeated here.

[0015] Overall, compared with the prior art, the above technical solutions conceived by the present application have the following beneficial effects: (1) The present application uses data interpolation on the scanning line bundle of the laser radar to increase the point cloud density, obtain encrypted point cloud data that meets the actual scanning requirements, and further provide scanning accuracy and scanning efficiency. Through precise and controllable mechanical movement, the laser radar is used to efficiently obtain ultra-high density and high precision point cloud data, and supports on-site intuitive evaluation, thereby overcoming many limitations of existing tunnel scanning methods in terms of density, efficiency, accuracy, cost and real-time performance. It has important engineering value for tunnel structure health monitoring, construction quality acceptance, BIM reverse modeling and other applications.

[0016] (2) The laser scanning device of the present application can determine the interpolation times according to the maximum interval of the scanning line bundle of the laser radar and the required data interval of the project, so as to improve the scanning accuracy and on-site detection speed of the project, and endow the on-site operator with intuitive online measurement capability, thereby achieving the goal of improving construction quality, reducing material consumption and improving work efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a laser scanning method flow diagram based on two-dimensional angle displacement table interpolation provided by the embodiment 1 of the present application; Figure 2 is a tunnel scanning interpolation diagram provided by the embodiment 1 of the present application; Figure 3 is a laser scanning device diagram based on two-dimensional angle displacement table interpolation provided by the embodiment 2 of the present application; Figure 4 is a laser detection and interpolation module structure diagram provided by the embodiment 2 of the present application; Figure 5 is an external structure diagram of a laser scanning device based on two-dimensional angle displacement table interpolation provided by the embodiment 2 of the present application.

[0018] In all the drawings, the same reference signs are used to represent the same elements or structures, wherein: 1 - shell, 2 - data processing display module, 3 - laser detection interpolation module, 3.1 - laser radar unit, 3.2 - radar support, 3.3 - Z-axis angular displacement unit, 3.4 - inclination sensor, 3.5 - Y-axis angular displacement unit, 4 - electronic control module, 5 - protective shell. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0020] The term "and / or" herein is a description of an association relationship of associated objects, which means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone. The symbol " / " in this paper represents the relationship of or, for example, A / B represents A or B.

[0021] The terms "first" and "second" and the like in the description and claims herein are used to distinguish different objects, not to describe a specific order of the objects. For example, the first response message and the second response message are used to distinguish different response messages, not to describe a specific order of the response messages.

[0022] In the embodiments of the present application, the words "exemplary" or "for example" are used to mean serving as an example, instance, or illustration. Any embodiment or design presented as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Rather, the use of "exemplary" or "for example" is intended to present concepts in a concrete manner.

[0023] In the description of the embodiments of the present application, unless otherwise specified, "a plurality of" means two or more, for example, a plurality of processing units means two or more processing units, and the like; a plurality of elements means two or more elements, and the like.

[0024] In tunnel construction, the scanning range of the laser radar is much larger than the radius size of 7 meters of a general tunnel, but the scanning density of the laser radar is very low, which cannot meet the operation requirements of a tunnel detection accuracy of ±2 cm. In order to meet the high-precision detection needs of tunnel engineering, the present application provides a laser scanning device based on a two-dimensional angular displacement table interpolation.

[0025] One embodiment of the present application will be described below in combination with the drawings in the embodiments of the present application.

[0026] Embodiment 1 The embodiment provides a laser scanning method based on two-dimensional angular displacement table interpolation, as shown in the figure, comprising the following steps: Figure 1 S1 drives the laser detection interpolation module 3 to rotate along the Y axis and the Z axis simultaneously or sequentially by using the two-dimensional angular displacement table, traverses the to-be-measured object to obtain preliminary point cloud data.

[0027] Specifically, as shown in the figure, the laser radar scanning included angle is 15°-45°, the beam included angle is 2°, the maximum laser scanning beam spacing is 270mm on the 7m distance from the laser emission point to the tunnel surface, and the actual scanning spacing required by the tunnel construction project is 20mm, which cannot meet the detection needs of the tunnel construction, so interpolation is required on the basis of the preliminary point cloud data to encrypt the preliminary point cloud data. Figure 2

[0028] S2 determines the number of interpolations of the preliminary point cloud data based on the maximum spacing of the laser scanning beam and the actual scanning requirement spacing of the to-be-measured object, and determines the rotation angle of the laser detection interpolation module 3 according to the number of interpolations.

[0029] Specifically, based on the maximum spacing 270mm of the aforementioned laser scanning beam and the actual scanning spacing 20mm required by the tunnel construction project, it is calculated that at least 13 groups of data need to be uniformly interpolated in the preliminary point cloud data to realize the requirement that the spacing between adjacent point cloud data is less than 20mm. The laser radar scanning included angle is equally divided according to the 13 groups of interpolation data to confirm the rotation angle each time.

[0030] S3 drives the laser detection interpolation module 3 to rotate sequentially according to the rotation angle by using the two-dimensional angular displacement table, and performs interpolation scanning at each rotation angle to obtain encrypted point cloud data.

[0031] Specifically, as shown in the figure, the laser detection interpolation module 3 is caused to rotate and scan the tunnel surface at the laser emission point according to the aforementioned divided rotation angle, and encrypted point cloud data is obtained on the basis of the preliminary point cloud data. Figure 2

[0032] After step S3, the encrypted point cloud data is also used to obtain the underbreak data cloud diagram or the overbreak data cloud diagram of the to-be-measured object. Specifically, the data processing display module 2 can compare the measured encrypted point cloud data with the ideal model data of the to-be-measured project (such as a tunnel), calculate and display the tunnel underbreak data cloud diagram or the overbreak data cloud diagram. For example, the encrypted point cloud data is first denoised, then the denoised data is point cloud resampled to unify the point cloud density, eliminate the density caused by interpolation, then coordinate system alignment processing is performed, finally, the difference is calculated by using the normal vector space projection method, and the calculation result is visualized to obtain the underbreak data cloud diagram and the overbreak data cloud diagram.

[0033] Embodiment 2​​​ This embodiment provides a laser scanning device based on two-dimensional angular displacement stage interpolation, such as... Figures 3-5 As shown, the laser scanning device includes an electronic control module 4 and a laser detection interpolation module 3, as well as a data processing and display module 2 and a two-dimensional angular displacement stage, both connected to the electronic control module. The laser detection interpolation module 3 is used to scan the object under test with a laser to obtain preliminary point cloud data. It is also used to scan the object under test sequentially according to the calculated rotation angle to interpolate the preliminary point cloud data and obtain encrypted point cloud data. In this embodiment, a multi-line mechanical rotating lidar can be selected, whose laser emitting unit is composed of 32 or 64 groups of vertically arranged laser diodes, and each beam of light is collimated through an independent lens. Alternatively, a solid-state Flash lidar can be selected, whose light source is a vertical cavity surface-emitting laser array, such as an 8×8 array.

[0034] The data processing and display module 2 is used to determine the number of interpolation operations on the preliminary point cloud data based on the maximum spacing of the laser scanning beams and the actual scanning spacing required by the object under test, and to determine the rotation angle of the laser detection interpolation module according to the number of interpolation operations. The data processing and display module 2 is also used to acquire and display under-drilling and over-drilling data cloud maps of the object under test based on the encrypted point cloud data. In this embodiment, the data processing and display module has an industrial-grade display screen as the data display unit and an embedded GPU processing unit as the data processing unit.

[0035] The electronic control module 4 is used to control the two-dimensional angular displacement stage to drive the laser detection interpolation module 3 to rotate, so as to scan the object to be measured to obtain preliminary point cloud data. It is also used to control the laser detection interpolation module 3 to rotate sequentially according to the calculated rotation angle, and to perform interpolation scanning at each rotation angle to obtain encrypted point cloud data.

[0036] Specifically, the electronic control module 4 is a conventional controller module that integrates a power supply, a drive unit, a control unit, etc. The electronic control module 4 is connected to the laser detection interpolation module 3 and the data processing and display module 2 respectively, and is used to supply power to the laser detection interpolation module 3 and the data processing and display module 2, and drive them to perform corresponding laser scanning and data processing actions.

[0037] The aforementioned laser detection interpolation module 3 includes a lidar unit 3.1 and a two-dimensional angular displacement stage. The lidar unit 3.1 is mounted on the two-dimensional angular displacement stage and can rotate around the X-axis. The two-dimensional angular displacement stage can drive the lidar unit to rotate simultaneously around the Y-axis and Z-axis, or rotate independently around the Y-axis or Z-axis. Specifically, the laser detection interpolation module 3 is fixed on the two-dimensional angular displacement stage and can rotate 360° around the X-axis.

[0038] The aforementioned two-dimensional angular displacement table comprises a radar support 3.2, a Z-axis angular displacement unit 3.3, a Y-axis angular displacement unit 3.5 and an inclination sensor 3.4 connected in sequence, the laser radar unit 3.1 is fixed on the radar support 3.2, and the laser exit end thereof faces away from the inclination sensor 3.4; the inclination sensor 3.4 is connected with the data processing and display module 2, which is used for detecting and acquiring the attitude data of the laser scanning device and transmitting the same to the data processing and display module 2; the electric control module 4 can control the Z-axis angular displacement unit 3.3 and the Y-axis angular displacement unit 3.5 to rotate simultaneously based on the attitude data, or the electric control module 4 can control the Z-axis angular displacement unit 3.3 or the Y-axis angular displacement unit 3.5 to rotate alone based on the attitude data.

[0039] The aforementioned radar support 3.2 is further provided with a damping system, for example, two-stage damping is realized by using a rubber shock pad and an active electromagnetic damper.

[0040] In the embodiment, the rotation accuracy (i.e. absolute rotation accuracy) of the two-dimensional angular displacement module composed of the Z-axis angular displacement unit 3.3 and the Y-axis angular displacement unit 3.5 is better than 0.14°, and the repeat positioning accuracy is not greater than 0.005°. Specifically, the two-dimensional angular displacement module adopts a high-reduction-ratio precision worm gear drive, which can realize arbitrary forward and reverse rotation; the guide is a precision arc V-shaped guide rail, which has high strength, strong load capacity and good durability.

[0041] The motion accuracy of the aforementioned two-dimensional angular displacement module is better than the interpolation motion accuracy of the laser radar scanning, so as to further improve the scanning accuracy, and the drive motor of the two-dimensional angular displacement module is further provided with a brake, which can lock the structure in the case of power failure, thereby protecting the safety of the radar.

[0042] The data processing unit and the data display unit of the aforementioned data processing and display module 2 are connected with each other. The data processing unit has control and operation functions, can compress the massive point cloud data with high quality and ensure the accuracy of the data; is further used for automatically splicing the results of multiple scans, fitting the point cloud data, and finally displaying the fitting results through the data display unit.

[0043] In the embodiment, as shown in FIG. 1, the laser radar unit 3.1 is fixed on the radar support 3.2, and the laser exit end thereof faces away from the inclination sensor 3.4. Figure 3 and 5As shown, the laser scanning device can further include a shell 1 and a protective shell 5, the electric control module 4 is fixedly arranged in the shell 1, the data processing and display module 2 and the laser detection and interpolation module 3 are arranged on a pair of side walls of the shell 1, and the data processing and display module 2 is located in the shell 1, and the data display end of the data display unit thereof faces outward of the shell 1, and the side wall of the shell 1 corresponding to the data display unit is a reversible side wall, which is closed to limit the data display unit in the shell 1 and is opened to expose the data display unit; the laser detection and interpolation module 3 is located outside the shell 1, and the laser emission end thereof faces away from the data display end; the protective shell 5 is arranged outside the laser detection and interpolation module 3 to prevent the laser detection and interpolation module 3 from being damaged by the outside, and the protective shell 5 is assembled and connected in alignment with the shell 1, so that the laser scanning device forms a highly integrated and portable device.

[0044] The base skeleton of the aforementioned shell 1 is made of aluminum, and the base skeleton is filled with foam, which has a damping effect and protects the components in the shell 1, and the side walls of the shell 1 are provided with heat dissipation channels, and heat dissipation fans (not shown in the figure) are arranged on the side walls opposite the heat dissipation channels.

[0045] The laser scanning method and device based on the two-dimensional angular displacement table interpolation provided in the application carry the laser radar on a high-precision two-dimensional angular displacement table, drive the laser radar to rotate through the two-dimensional angular displacement table, interpolate the data of the scanning line bundle of the laser radar, increase the point cloud density, and thus obtain the point cloud data meeting the requirements. The method and device can improve the scanning accuracy and the on-site detection speed, give the on-site operator intuitive online measurement capability, and thus achieve the goal of improving the construction quality, reducing the consumption of materials, and improving the work efficiency.

[0046] It should be understood that expressions such as "include" and "may include" used in the present application indicate the presence of the disclosed functions, operations or constituent elements, and do not limit one or more additional functions, operations and constituent elements. In the present application, terms such as "include" and / or "have" can be interpreted to mean that a specific feature, number, operation, constituent element, component or combination thereof is present, but cannot be interpreted to exclude the presence or addition of one or more other features, numbers, operations, constituent elements, components or combinations thereof.

[0047] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" can include A, can include B, or can include both A and B.

[0048] In the description of the embodiments of the present application, it should be noted that unless otherwise clearly specified and limited, the term "connection" should be understood broadly, for example, "connection" can be detachable connection, or can be non-detachable connection; can be direct connection, or can be indirect connection through intermediate medium. Among them, "fixed connection" refers to the relative position relationship after connection is unchanged. "Rotary connection" refers to the relative rotation after connection. "Sliding connection" refers to the relative sliding after connection. The orientation language mentioned in the embodiments of the present application, such as "top", "bottom", "inner", "outer", "left", "right", etc., is only the direction of the drawing, therefore, the orientation language used is to better, more clearly illustrate and understand the embodiments of the present application, and is not indicative or implied that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, therefore, it cannot be understood as a limitation on the embodiments of the present application.

[0049] In addition, in the embodiments of the present application, the mathematical concepts mentioned, such as symmetry, equality, parallel, perpendicular, etc. These limitations are all for the current process level, and are not strictly defined in the mathematical sense, and a small amount of deviation is allowed, such as approximately symmetric, approximately equal, approximately parallel, approximately perpendicular, etc. For example, A is parallel to B, which means that A and B are parallel or approximately parallel, and the included angle between A and B can be between 0 degrees and 10 degrees. A is perpendicular to B, which means that A and B are perpendicular or approximately perpendicular, and the included angle between A and B can be between 80 degrees and 100 degrees.

[0050] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A laser scanning method based on two-dimensional angular displacement stage interpolation, characterized in that, include: S1 uses a two-dimensional angular displacement stage to drive the laser detection interpolation module (3) to rotate and scan the object under test to obtain preliminary point cloud data; S2 determines the number of interpolation times for the preliminary point cloud data based on the maximum spacing of the laser scanning beams and the actual scanning requirement spacing of the object under test, and determines the rotation angle of the laser detection interpolation module (3) according to the number of interpolation times; S3 uses the two-dimensional angular displacement stage to drive the laser detection interpolation module (3) to rotate sequentially according to the rotation angle, and performs interpolation scanning at each rotation angle to obtain encrypted point cloud data.

2. The laser scanning method as described in claim 1, characterized in that, After step S3, the encrypted point cloud data is used to obtain the under-dug data cloud map or over-dug data cloud map of the object under test.

3. The laser scanning method as described in claim 1, characterized in that, The spacing between adjacent point clouds in the encrypted point cloud data is smaller than the actual scanning requirement spacing.

4. A laser scanning device for implementing the laser scanning method as described in any one of claims 1-3, characterized in that, It includes an electronic control module (4) and a laser detection interpolation module (3), as well as a data processing and display module (2) and a two-dimensional angular displacement stage, which are respectively connected to the electronic control module (4): The electronic control module (4) is used to control the two-dimensional angular displacement stage to drive the laser detection interpolation module (3) to rotate and scan the object to be measured in order to obtain preliminary point cloud data; The data processing and display module (2) is used to determine the number of interpolation times for the preliminary point cloud data based on the maximum spacing of the laser scanning beam and the actual scanning requirement spacing of the object under test, and to determine the rotation angle of the laser detection interpolation module (3) according to the number of interpolation times; The electronic control module (4) is also used to control the two-dimensional angular displacement stage to drive the laser detection interpolation module (3) to rotate sequentially according to the rotation angle, and to perform interpolation scanning at each rotation angle to obtain encrypted point cloud data.

5. The laser scanning device as described in claim 4, characterized in that, The laser detection interpolation module (3) includes a laser radar unit (3.1), which is mounted on a two-dimensional angular displacement stage. The laser radar unit (3.1) can rotate around the X-axis, and the two-dimensional angular displacement stage can drive the laser radar unit (3.1) to rotate around the Y-axis and / or Z-axis.

6. The laser scanning device as described in claim 5, characterized in that, The two-dimensional angular displacement stage includes a radar bracket (3.2), a Y-axis angular displacement unit (3.5), a Z-axis angular displacement unit (3.3), and a tilt sensor (3.4) connected in sequence. The lidar unit (3.1) is fixed on the radar bracket (3.2). The tilt sensor (3.4) is connected to the data processing and display module (2), which is used to detect and acquire the attitude data of the laser scanning device and transmit it to the data processing and display module (2). The electronic control module (4) can control the rotation of the Y-axis angular displacement unit (3.5) and / or the Z-axis angular displacement unit (3.3) based on the attitude data.

7. The laser scanning device as described in claim 5, characterized in that, The rotational accuracy of the two-dimensional angular displacement stage is better than 0.14°, and the repeatability is no greater than 0.005°.

8. The laser scanning device as described in claim 4, characterized in that, The data processing and display module (2) includes a data processing unit and a data display unit connected to each other. The data processing unit is used to obtain the under-dug data cloud map or over-dug data cloud map of the object under test using the encrypted point cloud data. The data display unit is used to display the under-dug data cloud map or over-dug data cloud map.

9. The laser scanning device as described in claim 4, characterized in that, It also includes a housing (1) and a protective shell (5). The electronic control module (4) is disposed inside the housing (1). The data processing and display module (2) and the laser detection interpolation module (3) are disposed on a pair of side walls of the housing (1). The data processing and display module (2) is located inside the housing (1) with its data display terminal facing outward from the housing (1). The laser detection interpolation module (3) is located outside the housing (1). The protective shell (5) covers the laser detection interpolation module (3) and is connected to the housing (1).

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