Method for improving three-dimensional positioning accuracy of laser ranging instruments based on directional point model

Abstract

The present invention relates to the field of precision measurement, and in particular to a method for improving the three-dimensional positioning accuracy of a laser rangefinder based on a directional point model. The method comprises designing and processing a directional point model, installing a reflective assembly on the processed directional point model, measuring the three-dimensional coordinates of each reflective assembly using a metrology-grade spatial posture measurement device, and measuring the distance between each laser rangefinder and each reflective assembly using each laser rangefinder; using the measurement results of the metrology-grade spatial posture measurement device and the measurement results of each laser rangefinder to calculate the three-dimensional coordinates of each laser rangefinder using a spatial intersection method; and using each laser rangefinder to measure the distance between each laser rangefinder and a target point, combining the distance with the three-dimensional coordinates of each laser rangefinder and calculating the three-dimensional coordinates of the target point using a spatial intersection method. The present invention can improve the measurement accuracy of laser rangefinders and achieve micron-level high-precision posture measurement.

Description

Technical Field

[0001] The present invention belongs to the field of precision measurement technology, and in particular relates to a method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model. Background Art

[0002] High-precision positioning is crucial in many precision measurement fields. With technological advancements, the requirements for precise positioning and alignment accuracy in aerospace, mechanical manufacturing and installation, optical system assembly, precision engineering, and industrial measurement are continuously increasing. Laser trackers, as a common high-precision 3D positioning tool, are widely used in these fields, particularly in assisting assembly and positioning. The accuracy of existing laser trackers, such as the Leica AT960 Tracker, is 15μm + 6μm / m over its full range. This error increases with increasing measurement distance, making it unable to meet the growing demand for positioning accuracy.

[0003] The laser tracker's measurement system is essentially a spherical coordinate measurement system. It calculates the target's three-dimensional coordinates by measuring the target's distance, horizontal, and vertical deflection angles. Therefore, the target's positioning accuracy is primarily affected by its ranging and angular measurement accuracy. Laser trackers measure distance based on the principle of laser interferometry and are capable of accurately measuring spatial distances. For example, the existing Leica AT960 IFM laser tracker has a ranging accuracy of up to 0.5μm / m. However, the laser tracker's angular measurement error remains the primary limiting factor. Focusing on high-precision ranging can significantly improve the positioning accuracy of the target.

[0004] Currently, a network adjustment method is commonly used to improve the positioning accuracy of target points. This method uses four or more laser trackers to perform joint measurements, using the coordinates measured by a single laser tracker as the initial values. Adjustment calculations are then performed using the high-precision distance data from pure ranging mode, thereby improving the positioning accuracy of the target points. This method significantly improves the positioning accuracy of target points by eliminating the angular measurement errors of the laser trackers and leveraging the high precision of laser interferometry ranging. However, due to the low accuracy and lack of stability of the coordinates measured by a single laser tracker, the measurement results are limited by the accuracy of the initial values.

[0005] A Chinese invention patent, published on March 19, 2024, with publication number CN117724041A, proposes a laser multilateration measurement method and system based on spatial multi-distance constraints, aiming to improve measurement accuracy. However, this measurement method can only obtain relative distances and only provides distance constraints within the horizontal plane, resulting in a complex layout process and a final accuracy of only approximately 10μm, making it difficult to meet higher positioning accuracy requirements. Summary of the Invention

[0006] In view of this, the present invention aims to provide a method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model, so as to solve the technical problem of low positioning accuracy of existing laser ranging instruments.

[0007] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0008] A method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model comprises the following steps:

[0009] S1: Design a geometrically stable directional point model based on the uniform distribution principle and polygon stability principle;

[0010] S2: Process the designed orientation point model and reasonably arrange the orientation points on the processed orientation point model to ensure that each laser ranging instrument can observe all orientation points;

[0011] S3: Install a reflective component at each orientation point, measure the three-dimensional coordinates of each reflective component using metrology-grade spatial pose measurement equipment, and arrange at least three measuring stations. Place a laser rangefinder at each measuring station, and use each laser rangefinder to measure the distance between each station and each reflective component.

[0012] S4: Using the three-dimensional coordinates of each reflective component and the distance between each laser ranging instrument and each reflective component, a spatial resection method based on the least squares method is used to calculate the three-dimensional coordinates of each measuring station;

[0013] S5: Install the reflective component on the target point, use each laser ranging instrument to measure the distance between each and the target point, and combine it with the three-dimensional coordinates of each measuring station. Calculate the three-dimensional coordinates of the target point using the spatial forward intersection method based on the least squares method.

[0014] Furthermore, in step S4, the three-dimensional coordinates of the first reflection component are set to , the three-dimensional coordinates of the remaining reflection components are , the three-dimensional coordinates of a certain measuring station are , then the distance between the first reflective component and the laser ranging instrument corresponding to the measuring station is for:

[0015]

[0016] The distance between the remaining reflective components and the laser ranging instrument corresponding to the measuring station for:

[0017]

[0018] Decomposing equations (1) and (2) yields:

[0019]

[0020]

[0021] Combining equations (3) and (4) we get:

[0022]

[0023] Arranging formula (5) yields:

[0024]

[0025] Assume that the number of reflection components is six, and the three-dimensional coordinates of the first reflection component are , the three-dimensional coordinates of the remaining reflection components are ~ , formula (6) is transformed into an overdetermined system of equations:

[0026]

[0027] The three-dimensional coordinates of the measuring station are obtained by the least squares method Solve and obtain the three-dimensional coordinates of the measuring station.

[0028] Furthermore, in step S5, the three-dimensional coordinates of the first measuring station are set to , the three-dimensional coordinates of the reflection components of the other station points are , the three-dimensional coordinates of the target point are , then the distance between the first measuring station and the target point for:

[0029]

[0030] The distance between the other measuring stations and the laser ranging instrument corresponding to the target point for:

[0031]

[0032] Decomposing equations (8) and (9) yields:

[0033]

[0034]

[0035] Combining equations (10) and (11), we can obtain:

[0036]

[0037] Arranging formula (12) yields:

[0038] ;

[0039] Assume that there are four measuring stations, and the three-dimensional coordinates of the first measuring station are The three-dimensional coordinates of the other measuring stations are ~ , formula (13) is transformed into a system of equations:

[0040]

[0041] Three-dimensional coordinates of the target point Solve and obtain the three-dimensional coordinates of the target point.

[0042] Furthermore, the orientation point model is a cube frame, including eleven horizontal bars and four vertical bars. The first horizontal bar, the second horizontal bar, the third horizontal bar, and the fourth horizontal bar constitute the bottom surface of the cube frame, the fifth horizontal bar, the sixth horizontal bar, the seventh horizontal bar, and the eighth horizontal bar constitute the top surface of the cube frame, the first horizontal bar, the fifth horizontal bar, the first vertical bar and the second vertical bar, the second horizontal bar, the sixth horizontal bar, the second vertical bar and the third vertical bar, the third horizontal bar, the seventh horizontal bar, the third vertical bar and the fourth vertical bar, the fourth horizontal bar, the eighth horizontal bar, the first vertical bar and the fourth vertical bar respectively constitute the four side surfaces of the cube frame, the ninth horizontal bar is connected between the midpoint of the fifth horizontal bar and the midpoint of the seventh horizontal bar, the tenth horizontal bar is connected between the midpoint of the third vertical bar and the midpoint of the fourth vertical bar, and the eleventh horizontal bar is connected between the midpoint of the fourth vertical bar and the midpoint of the first vertical bar.

[0043] Furthermore, the material of the directional point model is silicon carbide composite material, titanium alloy material, Invar alloy material or carbon fiber 3D printing material.

[0044] Furthermore, there are six orientation points, which are respectively arranged at the two ends of the first crossbar, the midpoints of the ninth crossbar, the tenth crossbar, the eleventh crossbar, and the intersection of the seventh crossbar and the eighth crossbar.

[0045] Furthermore, the metrology-grade spatial posture measurement equipment is a three-coordinate measuring machine.

[0046] Furthermore, the laser ranging instrument is a laser tracker, a laser interferometer or a laser tracking interferometer. When the laser ranging instrument is a laser tracker, the reflective component adopts a target ball specially used for the laser tracker; when the laser ranging instrument is a laser tracking interferometer, the reflective component adopts a cat's eye retroreflector specially used for the laser tracking interferometer; when the laser ranging instrument is a laser interferometer, the reflective component adopts a plane reflector, a corner cube prism, a right-angle prism or a cat's eye retroreflector specially used for the laser interferometer.

[0047] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0048] The present invention utilizes a spatial multi-distance constrained directional point model and the high-precision ranging technology of a laser ranging instrument to obtain high-precision measuring station coordinates, laying a high-precision measuring station foundation for subsequent network adjustment, thereby improving the measurement accuracy of the laser ranging instrument and achieving micron-level high-precision posture measurement, meeting the requirements for precise system positioning and adjustment accuracy in fields such as aerospace, mechanical manufacturing and installation, optical system adjustment, and precision engineering and industrial measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0050] Figure 1 The present invention is a flowchart of a method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to an embodiment of the present invention.

[0051] Figure 2 2 is a schematic structural diagram of a directional point model according to an embodiment of the present invention.

[0052] Figure 3 It is a schematic diagram of a spatial intersection formed by a reflective assembly and a laser ranging instrument according to an embodiment of the present invention.

[0053] Figure 4 This is a schematic diagram of intersection measurement of a laser ranging instrument according to an embodiment of the present invention.

[0054] Figure 5 It is a schematic diagram of the spatial forward intersection formed by the target point and the laser ranging instrument according to the embodiment of the invention.

[0055] Explanation of the accompanying drawings: orientation point model 1, first reflection component 11, second reflection component 12, third reflection component 13, fourth reflection component 14, fifth reflection component 15, sixth reflection component 16, first cross bar 101, second cross bar 102, third cross bar 103, fourth cross bar 104, fifth cross bar 105, sixth cross bar 106, seventh cross bar 107, eighth cross bar 108, ninth cross bar 109, tenth cross bar 110, eleventh cross bar 111, first vertical bar 112, second vertical bar 113, third vertical bar 114, fourth vertical bar 115, laser ranging instrument 21, target 3, target point 31. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0057] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other.

[0058] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second" and the like are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, features defined as "first", "second" and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0059] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art can understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0060] The following will refer to Figure 1-Figure 5 The present invention is described in detail with reference to the embodiments.

[0061] like Figure 1 As shown, the method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model provided by an embodiment of the present invention includes the following steps:

[0062] S1: Design a geometrically stable directional point model based on the uniform distribution principle and polygon stability principle.

[0063] S2: Process the designed orientation point model and reasonably arrange the orientation points on the processed orientation point model to ensure that each laser ranging instrument can observe all orientation points.

[0064] Based on the principle of uniform distribution and polygon stability, ensure that the orientation points are evenly distributed on the XY, XZ, and YZ planes, and at the same time cover the angle areas between the planes as much as possible, so that these angle surfaces have geometric constraints. In the design, the geometric constraints of the orientation points should be avoided from being too concentrated on a certain point or a certain area, and should be evenly distributed on all orientation points to ensure the overall geometric stability and measurement accuracy of the orientation point model. Under the premise of ensuring that each laser ranging instrument can see all orientation points, a geometrically stable orientation point model is designed by reasonably arranging the orientation points, thereby achieving the best balance between accuracy and stability. For example, the orientation point model is a cube frame structure, such as Figure 2 As shown, the orientation point model of the cube frame structure includes a first crossbar 101, a second crossbar 102, a third crossbar 103, a fourth crossbar 104, a fifth crossbar 105, a sixth crossbar 106, a seventh crossbar 107, an eighth crossbar 108, a ninth crossbar 109, a tenth crossbar 110, an eleventh crossbar 111, a first vertical bar 112, a second vertical bar 113, a third vertical bar 114 and a fourth vertical bar 115. The first crossbar 101, the second crossbar 102, the third crossbar 103 and the fourth crossbar 104 constitute the bottom surface of the cube frame, the fifth crossbar 105, the sixth crossbar 106, the seventh crossbar 107 and the eighth crossbar 108 constitute the top surface of the cube frame, and the first crossbar 101, the fifth crossbar 103 and the fourth crossbar 104 constitute the top surface of the cube frame. 05, the first vertical rod 112 and the second vertical rod 113 and the second crossbar 102, the sixth crossbar 106, the second vertical rod 113 and the third vertical rod 114 and the third crossbar 103, the seventh crossbar 107, the third vertical rod 114 and the fourth vertical rod 115 and the fourth crossbar 104, the eighth crossbar 108, the first vertical rod 112 and the fourth vertical rod 115 respectively constitute the four side faces of the cube frame, the ninth crossbar 109 is connected between the midpoint of the fifth crossbar 105 and the midpoint of the seventh crossbar 107, the tenth crossbar 110 is connected between the midpoint of the third vertical rod 114 and the midpoint of the fourth vertical rod 115, and the eleventh crossbar 111 is connected between the midpoint of the fourth vertical rod 115 and the midpoint of the first vertical rod 112.

[0065] The orientation point model of the present invention is not limited to the above-mentioned cube frame structure, and other regular polyhedron frame structures can also be used as long as the geometric stability requirements are met.

[0066] The material of the directional point model can be silicon carbide composite material, titanium alloy material, Invar alloy material or carbon fiber 3D printing material.

[0067] Invar (Fe-Ni alloy) material: extremely low thermal expansion coefficient (~1×10⁻ 6 / °C), suitable for precision optical and metrological instrument structures. Because the material is relatively soft, it can deform significantly during machining, easily generating machining stress during cutting, which affects accuracy. Therefore, orientation point models can be processed through welding or precision casting, but more complex orientation point models still require subsequent finishing.

[0068] Titanium alloy (Ti-6Al-4V): Lighter than steel, more rigid, and corrosion-resistant, it is suitable for high-precision instrument frames. Its high strength allows for integrated machining of directional point models using diamond cutting tools or laser cutting.

[0069] Carbon fiber 3D printing materials (metal laser melting L-PBF, electron beam melting EBM): integrated manufacturing of directional point models through 3D printing.

[0070] Silicon carbide composites (C / SiC): More heat-resistant and dimensional-stable than pure carbon fiber. They can be processed using diamond tools or laser cutting for integrated processing of directional point models.

[0071] The selection of orientation points should avoid being concentrated on a certain surface or area of the regular polyhedron framework structure, and should cover the angle areas between various planes as much as possible, so that these angle surfaces have geometric constraints and provide more dimensions.

[0072] S3: Install a reflective component at each orientation point, measure the three-dimensional coordinates of each reflective component using metrology-grade spatial posture measurement equipment, and set up at least three measuring stations. Place a laser rangefinder at each measuring station, and use each laser rangefinder to measure the distance between each station and each reflective component.

[0073] The distance between the reflective component and the measuring station is measured using a laser rangefinder. Laser rangefinders utilize laser trackers, laser interferometers, or laser tracking interferometers. When using a laser tracker, the laser tracker's angle weighting is disabled, and the laser tracker's precise distance measurement function is used to measure the distance to each reflective component. In this case, the reflective component utilizes a spherically mounted retroreflector (SMR) specifically designed for laser tracker systems. When using a laser tracking interferometer, the reflective component utilizes a cat's eye retroreflector (CER) specifically designed for laser tracking interferometer systems. When using a laser interferometer, the reflective component utilizes a plane reflector, corner cube, right-angle prism, or cat's eye retroreflector specifically designed for laser interferometers.

[0074] Laser interferometers typically achieve nanometer or submicron accuracy, making them suitable for high-precision distance measurement. However, their measurement range is typically small, typically within a few meters (e.g., 1 to 5 meters). Therefore, they are unsuitable for large-scale spatial positioning measurements, but only for small-scale ones. The present invention utilizes a laser tracker or laser tracking interferometer for large-scale spatial positioning measurements, while the present invention utilizes a laser interferometer for small-scale spatial positioning measurements.

[0075] Take six orientation points as an example, Figure 2 As shown, each orientation point corresponds to a reflective assembly, and the six reflective assemblies are the first reflective assembly 11, the second reflective assembly 12, the third reflective assembly 13, the fourth reflective assembly 14, the fifth reflective assembly 15, and the sixth reflective assembly 16. The first reflective assembly 11 is arranged at the intersection of the seventh crossbar 107 and the eighth crossbar 108, the second reflective assembly 12 is arranged at the midpoint of the eleventh crossbar 111, the third reflective assembly 13 is arranged at the midpoint of the tenth crossbar 110, the fourth reflective assembly 14 is arranged at the midpoint of the ninth crossbar 109, and the fifth reflective assembly 15 and the sixth reflective assembly 16 are arranged at both ends of the first crossbar 101. That is, the six orientation points are distributed on a cube frame.

[0076] If the sixth reflective component 16 is arranged near the top surface of the cube, the plane formed by the first reflective component 11, the second reflective component 12, and the sixth reflective component 16 is redundant with the plane formed by the first reflective component 11, the second reflective component 12, and the third reflective component 13. Therefore, the sixth reflective component 16 is arranged near the bottom surface of the cube to expand more dimensions.

[0077] The first reflective component 11, the second reflective component 12, the third reflective component 13, the fourth reflective component 14, the fifth reflective component 15, and the sixth reflective component 16 are respectively installed on the cube frame through the reflective component seat. The reflective component seat can be integrally processed and formed with the cube frame, or the reflective component seat can be fixed on the cube frame after the cube frame is processed.

[0078] The metrology-grade spatial posture measurement equipment uses a three-dimensional coordinate measuring machine to measure the three-dimensional coordinates of the first reflective component 11, the second reflective component 12, the third reflective component 13, the fourth reflective component 14, the fifth reflective component 15, and the sixth reflective component 16. Since the three-dimensional coordinate measuring machine has extremely high measurement accuracy, it can obtain high-precision three-dimensional coordinates of the reflective components.

[0079] S4: Using the three-dimensional coordinates of each reflective component and the distance between each laser ranging instrument and each reflective component, the three-dimensional coordinates of each measuring station are calculated using a spatial resection method based on the least squares method.

[0080] The three-dimensional coordinates of each station are calculated in the same way. Figure 3 The laser ranging instrument 21) is used as an example for explanation.

[0081] Let the three-dimensional coordinates of the first reflection component be , the three-dimensional coordinates of the remaining reflection components are , the three-dimensional coordinates of a certain measuring station are , then the distance between the first reflective component and the laser ranging instrument corresponding to the measuring station is for:

[0082]

[0083] The distance between the remaining reflective components and the laser ranging instrument corresponding to the measuring station for:

[0084]

[0085] Decomposing equations (1) and (2) yields:

[0086]

[0087]

[0088] Combining equations (3) and (4) we get:

[0089]

[0090] Arranging formula (5) yields:

[0091]

[0092] Formula (6) is transformed into an overdetermined system of equations:

[0093]

[0094] 3D coordinates of the measuring station The unknown number is solved by using the spatial intersection method to obtain the three-dimensional coordinates of the measuring station. The spatial intersection formed by the reflector component and the laser ranging instrument is as follows: Figure 3 As shown in the figure, since the solution process of the resection method involves multiple known orientation points and their measurement data, the use of the least squares method can effectively reduce the error in the measurement and ensure that the three-dimensional coordinates of the final station are highly accurate.

[0095] like Figure 4As shown in FIG, when four or more laser ranging instruments are used, all laser ranging instruments are combined with all reflection components to form a side measurement network adjustment, which can further improve the three-dimensional coordinate accuracy of the measuring station.

[0096] S5: Install the reflective component on the target point, use each laser ranging instrument to measure the distance between each and the target point, and combine it with the three-dimensional coordinates of each measuring station. Calculate the three-dimensional coordinates of the target point using the spatial forward intersection method based on the least squares method.

[0097] like Figure 5 As shown, the camera's adjustment device is used as the target 3, and the three vertices of the adjustment device are used as the target point 31. The three-dimensional coordinates of the target point 31 are calculated respectively. Since the calculation method is the same, only the three vertices of the target point 31 are used. Figure 5 The target point 31 shown is taken as an example for detailed description.

[0098] Assume the three-dimensional coordinates of the first measuring station are , the three-dimensional coordinates of the reflection components of the other station points are , the three-dimensional coordinates of the target point are , then the distance between the first measuring station and the target point for:

[0099]

[0100] The distance between the other measuring stations and the laser ranging instrument corresponding to the target point for:

[0101]

[0102] Decomposing equations (8) and (9) yields:

[0103]

[0104]

[0105] Combining equations (10) and (11), we can obtain:

[0106]

[0107] Arranging formula (12) yields:

[0108] ;

[0109] Assume that there are four measuring stations, and the three-dimensional coordinates of the first measuring station are The three-dimensional coordinates of the other measuring stations are ~ , formula (13) is transformed into a system of equations:

[0110]

[0111] Due to the three equations and three unknowns, the three-dimensional coordinates of the target point are directly Solve and obtain the three-dimensional coordinates of the target point.

[0112] When the number of measuring stations is four or more, Equation (13) becomes an overdetermined system of equations and is solved by the least squares method.

[0113] The measurement method provided by this invention utilizes a spatial multi-distance constrained directional point model and the high-precision ranging technology of a laser rangefinder to achieve high-precision three-dimensional positioning measurement. It also simplifies the process, improves measurement efficiency, and reduces operational complexity. This simple and efficient measurement method is suitable for applications requiring high-precision positioning, such as aerospace, precision manufacturing, and optical system assembly, and has strong potential for widespread application.

[0114] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0115] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model, characterized in that: The steps include: S1: Design a geometrically stable directional point model based on the uniform distribution principle and polygon stability principle; S2: Process the designed orientation point model and arrange the orientation points reasonably on the processed orientation point model to ensure that each laser ranging instrument can observe all orientation points; the orientation point model is a hollow regular polyhedron frame structure; the orientation points are evenly distributed on the XY, XZ, and YZ planes; S3: Install a reflective component at each orientation point, measure the three-dimensional coordinates of each reflective component using a coordinate measuring machine, and arrange at least three measuring stations. Place a laser rangefinder at each measuring station, and use each laser rangefinder to measure the distance between each station and each reflective component. S4: Using the three-dimensional coordinates of each reflective component and the distance between each laser ranging instrument and each reflective component, a spatial resection method based on the least squares method is used to calculate the three-dimensional coordinates of each measuring station; S5: Install the reflective component on the target point, use each laser ranging instrument to measure the distance between each and the target point, and combine it with the three-dimensional coordinates of each measuring station. Calculate the three-dimensional coordinates of the target point using the spatial forward intersection method based on the least squares method.

2. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 1, characterized in that: In step S4, the three-dimensional coordinates of the first reflection component are set to , the three-dimensional coordinates of the remaining reflection components are , the three-dimensional coordinates of a certain measuring station are , then the distance between the first reflective component and the laser ranging instrument corresponding to the measuring station is for: The distance between the remaining reflective components and the laser ranging instrument corresponding to the measuring station for: Decomposing equations (1) and (2) yields: Combining equations (3) and (4) we get: Arranging formula (5) yields: Assume that the number of reflection components is six, and the three-dimensional coordinates of the first reflection component are , the three-dimensional coordinates of the remaining reflection components are ~ , formula (6) is transformed into an overdetermined system of equations: The three-dimensional coordinates of the measuring station are obtained by the least squares method Solve and obtain the three-dimensional coordinates of the measuring station.

3. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 1, characterized in that: In step S5, the three-dimensional coordinates of the first measuring station are set to , the three-dimensional coordinates of the reflection components of the other station points are , the three-dimensional coordinates of the target point are , then the distance between the first measuring station and the target point for: The distance between the remaining measuring stations and the laser ranging instrument corresponding to the target point for: Decomposing equations (8) and (9) yields: Combining equations (10) and (11), we can obtain: Arranging formula (12) yields: ； Assume that there are four measuring stations, and the three-dimensional coordinates of the first measuring station are The three-dimensional coordinates of the other measuring stations are ~ , formula (13) is transformed into a system of equations: Three-dimensional coordinates of the target point Solve and obtain the three-dimensional coordinates of the target point.

4. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 1, characterized in that: The orientation point model is a cube frame, including eleven horizontal bars and four vertical bars. The first horizontal bar, the second horizontal bar, the third horizontal bar, and the fourth horizontal bar constitute the bottom surface of the cube frame, the fifth horizontal bar, the sixth horizontal bar, the seventh horizontal bar, and the eighth horizontal bar constitute the top surface of the cube frame, the first horizontal bar, the fifth horizontal bar, the first vertical bar and the second vertical bar, the second horizontal bar, the sixth horizontal bar, the second vertical bar and the third vertical bar, the third horizontal bar, the seventh horizontal bar, the third vertical bar and the fourth vertical bar, and the fourth horizontal bar, the eighth horizontal bar, the first vertical bar and the fourth vertical bar respectively constitute the four side surfaces of the cube frame, the ninth horizontal bar is connected between the midpoint of the fifth horizontal bar and the midpoint of the seventh horizontal bar, the tenth horizontal bar is connected between the midpoint of the third vertical bar and the midpoint of the fourth vertical bar, and the eleventh horizontal bar is connected between the midpoint of the fourth vertical bar and the midpoint of the first vertical bar.

5. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 4, characterized in that: The material of the directional point model is silicon carbide composite material, titanium alloy material, Invar alloy material or carbon fiber 3D printing material.

6. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 4, characterized in that: There are six orientation points, which are respectively arranged at the two ends of the first crossbar, the midpoints of the ninth crossbar, the tenth crossbar, the eleventh crossbar, and the intersection of the seventh crossbar and the eighth crossbar.

7. The method for improving the three-dimensional positioning accuracy of a laser ranging instrument based on a directional point model according to claim 1, characterized in that: The laser ranging instrument is a laser tracker, a laser interferometer or a laser tracking interferometer. When the laser ranging instrument is a laser tracker, the reflective component adopts a target ball specially used for the laser tracker; when the laser ranging instrument is a laser tracking interferometer, the reflective component adopts a cat's eye retro-reflective mirror specially used for the laser tracking interferometer; when the laser ranging instrument is a laser interferometer, the reflective component adopts a plane reflector, a corner cube prism, a right-angle prism or a cat's eye retro-reflective mirror specially used for the laser interferometer.

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