Method for establishing a reference coordinate system based on a target device used as a reference benchmark

Abstract

The present invention relates to the field of image measurement technology, and particularly to a method for establishing a reference coordinate system based on a target device used as a reference benchmark. The target device includes a base, a three-dimensional attitude adjustment mechanism, and a reference target. The three-dimensional attitude adjustment mechanism is installed on the base, and the reference target is fixed to the three-dimensional attitude adjustment mechanism. The reference target is made of hard alloy steel and has a cubic shape. The method includes the steps of: setting the positive directions of the X S , Y S , and Z S axes; determining the X S coordinate component, Y S0 coordinate component, and Z S0 coordinate component of the origin O S0 . Through the positive directions of the X S , Y S , and Z S axes set in the above steps and the three-dimensional coordinates (X S , Y S0 , Z S0 ) of the origin O S0 calculated, the establishment of the reference coordinate system O S -X S Y S Z S is completed. The purpose of the method for establishing a reference coordinate system based on a target device used as a reference benchmark is to solve the problem that a standard sphere cannot meet the reference benchmark of an industrial image measurement system.

Description

Technical Field

[0001] The present invention relates to the technical field of image measurement, and particularly relates to a method for establishing a reference coordinate system based on a target device used as a reference benchmark. Background Art

[0002] Geometric measurement is one of the important branches in the field of measurement, which refers to the experimental process for determining the value of the measured geometric quantity. In recent years, with the development of various new technologies, especially computer technology, geometric measurement devices and systems have shown a trend of coordinate transformation, automation, and intelligence. This not only significantly improves the measurement accuracy of the instrument and equipment, but also reduces the manufacturing cost of the instrument and equipment, realizes the versatility and applicability of the instrument and equipment, and thus meets the measurement requirements of modern industrial production with multiple varieties, small batches, and rapid changes. Among them, the industrial image measurement system is a relatively new type of geometric measurement instrument, which is an organic combination of image processing technology and coordinate measurement technology, and is a coordinate measuring machine equipped with a non-contact optical image probe or an industrial camera. The industrial image measurement system provides a measurement means for two-dimensional parameter measurement, and the latest technological development enables it to also measure the parameters of the surface of three-dimensional objects. Therefore, since the beginning of this century, the industrial image measurement system has been more and more widely used in enterprises, research institutions, and production sites.

[0003] The industrial image measurement system uses an industrial camera to collect the image of the workpiece to be measured, extracts the coordinate points on the surface of various complex-shaped workpieces through digital image processing technology, and then converts them into various geometric elements in the coordinate measurement space by using coordinate transformation and data processing technology, so as to calculate the actual size, shape, and mutual position relationship of the workpiece to be measured. During the application process, it is usually necessary to set up and establish a reference coordinate system. The reference coordinate system is a reference benchmark established based on a fixed point on the workbench of the industrial image measurement system, so that even when the industrial camera is changed or the system is restarted after shutdown, the mutual position relationship between each element can still be simply and quickly restored according to this reference benchmark.

[0004] For a traditional contact three - coordinate measuring machine, the reference coordinate system is usually set on a standard ball fixed on the workbench. By measuring a standard ball fixed on the workbench of the three - coordinate measuring machine, and then taking its ball center as the origin to establish the reference coordinate system. For a non - contact industrial image measuring system, its front - end sensor is an industrial camera. Different from conventional contact probes and laser triangulation probes, it has a certain depth - of - field range and outputs a two - dimensional image of the measured object. At the same time, during the imaging process of the industrial camera, a two - dimensional image of the measured object is formed by projecting a three - dimensional scene onto a two - dimensional image plane, losing the spatial depth information and unable to make the standard ball lie on the object - side focal plane of the industrial camera. Therefore, standard balls with three - dimensional spatial characteristics are not suitable as the reference benchmark for industrial image measuring systems, and it is impossible to use them to establish the reference coordinate system. Since the output of the industrial camera is a two - dimensional image of the measured object and is sensitive to abrupt parts such as the edges and sharp corners of the measured object, it is necessary to set the reference benchmark according to its own characteristics to determine and establish the reference coordinate system in the industrial image measuring system.

[0005] In an industrial image measuring system with an industrial camera as the front - end sensor, a fixed and unchanging point is required as the reference benchmark to establish the reference coordinate system, so that when the industrial camera is changed or restarted after shutdown, the mutual position relationship between various elements can still be restored according to this reference benchmark. Industrial image measuring systems are usually used to achieve two - dimensional plane measurement, and general standard balls with three - dimensional spatial characteristics cannot be on the object - side focal plane of the industrial camera, so they are not suitable as the reference benchmark for such measuring systems.

[0006] Therefore, the inventor provides a method for establishing a reference coordinate system based on a target device used as a reference benchmark. Summary of the Invention

[0007] (1) Technical problems to be solved

[0008] The embodiment of the present invention provides a method for establishing a reference coordinate system based on a target device used as a reference benchmark, which solves the technical problem that the standard ball cannot meet the reference benchmark of the industrial image measuring system.

[0009] (2) Technical solutions

[0010] The present invention provides a method for establishing a reference coordinate system based on a target device used as a reference benchmark. The target device includes a base, a three - dimensional attitude adjustment mechanism, and a reference target. The three - dimensional attitude adjustment mechanism is installed on the base, and the reference target is fixed to the three - dimensional attitude adjustment mechanism. The reference target is made of hard alloy steel and has a cubic shape. Wherein, the method includes the following steps:

[0011] Determine the reference coordinate system O S -X S Y S Z S The positive directions of the X S axis, Y S axis, and Z S axis are the same as the positive directions of the X-axis, Y-axis, and Z-axis of the machine coordinate system O-XYZ of the industrial image measurement system respectively;

[0012] Move the industrial camera. When the front surface of the reference target is on the object-side focal plane of the industrial camera, determine the grating scale reading of the X linear motion axis as the reference coordinate system O S -X S Y S Z S The origin O S The X S0 coordinate component;

[0013] Lock the X-axis and move the industrial camera along the Y-axis direction. When the front edge of the reference target is at the center of the field of view of the industrial camera, determine the grating scale reading of the Y linear motion axis as the reference coordinate system O S -X S Y S Z S The origin O S The Y S0 coordinate component;

[0014] Lock the X-axis and move the industrial camera along the Z-axis direction. When the upper edge of the reference target is at the center of the field of view of the industrial camera, determine the grating scale reading of the Z linear motion axis as the reference coordinate system O S -X S Y S Z S The origin O S The Z S0 coordinate component;

[0015] Based on the positive directions of the X S axis, Y S axis, and Z S axis, and the calculated three-dimensional coordinates (X S , Y S0 , Z S0 , Z S0 ) of the origin O, establish the reference coordinate system O S -X S Y S Z S .

[0016] Furthermore, each surface of the reference target is a smooth, flat, and uniformly textured matte surface.

[0017] Furthermore, the flatness error of each surface of the reference target is ≤ 2 μm.

[0018] Furthermore, each edge of the reference target is a sharp, continuous, and complete straight edge.

[0019] Furthermore, the three-dimensional attitude adjustment mechanism includes a one-dimensional manual angular position stage A, a one-dimensional manual angular position stage B, a one-dimensional manual rotary stage, a plurality of locking nuts, and a plurality of adjusting handles. The reference target is installed on the one-dimensional manual rotary stage;

[0020] The one-dimensional manual angular position stage A and the one-dimensional manual angular position stage B are stacked and installed in sequence, and are respectively used to adjust the rotation angle α of the reference target around the X-axis and the rotation angle β around the Y-axis under the drive of the corresponding adjusting handle, and the position is locked by the corresponding locking nut;

[0021] The one-dimensional manual rotary stage is stacked and installed on the one-dimensional manual angular position stage A or the one-dimensional manual angular position stage B, and is used to adjust the rotation angle γ of the reference target around the Z-axis under the drive of the corresponding adjusting handle, and the position is locked by the corresponding locking nut.

[0022] Furthermore, the target device used as a reference also includes a protective cover, and the protective cover covers the base, the three-dimensional attitude adjustment mechanism, and the reference target.

[0023] Furthermore, the protective cover is a transparent cubic hollow shell.

[0024] Furthermore, a window is opened on the front surface of the protective cover.

[0025] Furthermore, the protective cover is used to be fixed on the workbench of the industrial image measurement system.

[0026] (3) Beneficial effects

[0027] In summary, the present invention adopts a specially designed geometric structure feature for the reference target in the target device used as a reference. It has a smooth, flat, and uniformly textured matte surface and sharp, continuous, and complete edges, which is convenient for the automatic focusing of the industrial camera and the accurate recognition and extraction of the edges. Moreover, it has the characteristics of simple geometric features, easy processing, and easy guarantee of geometric and positional accuracy, and is the best measurement object for the industrial camera. This method realizes the establishment of the reference coordinate system by automatically focusing on the reference target by the industrial camera and accurately recognizing and extracting the edges, giving full play to the advantages of the industrial image measurement system in measuring plane features, and has the characteristics of simple principle, convenient use, and easy realization of automation. Description of the drawings

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments of the present invention. Obviously, the following described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 It is a schematic flowchart of a method for establishing a reference coordinate system based on a target device used as a reference benchmark provided by an embodiment of the present invention;

[0030] Figure 2 It is a schematic structural diagram of a target device used as a reference benchmark provided by an embodiment of the present invention;

[0031] Figure 3 It is a schematic structural diagram of a three-dimensional attitude adjustment mechanism of a target device used as a reference benchmark provided by an embodiment of the present invention;

[0032] Figure 4 It is a schematic structural diagram of a reference target of a target device used as a reference benchmark provided by an embodiment of the present invention;

[0033] Figure 5 It is a schematic structural diagram of a protective cover of a target device used as a reference benchmark provided by an embodiment of the present invention;

[0034] Figure 6 It is a schematic diagram of a reference coordinate system provided by an embodiment of the present invention;

[0035] Figure 7 It is a schematic diagram of a process for establishing a reference coordinate system provided by an embodiment of the present invention;

[0036] Figure 8 It is an image schematic diagram when the front edge of the reference target is at the center of the field of view of the industrial camera provided by an embodiment of the present invention;

[0037] Figure 9 It is an image schematic diagram when the upper edge of the reference target is at the center of the field of view of the industrial camera provided by an embodiment of the present invention.

[0038] In the figure:

[0039] 1 - base; 11 - mounting hole; 2 - three-dimensional attitude adjustment mechanism; 21 - one-dimensional manual angular position table A; 22 - one-dimensional manual angular position table B; 23 - one-dimensional manual rotating table; 24 - locking nut; 25 - adjusting handle; 3 - reference target; 31 - front surface of the reference target; 32 - upper surface of the reference target; 33 - side surface of the reference target; 34 - upper edge of the reference target; 35 - front edge of the reference target; 4 - protective cover; 41 - front surface of the protective cover; 411 - window; 5 - industrial camera. Detailed implementation mode

[0040] The following further describes in detail the implementation mode of the present invention in conjunction with the accompanying drawings and embodiments. The following detailed description of the embodiments and the accompanying drawings are used to exemplarily illustrate the principle of the present invention, but cannot be used to limit the scope of the present invention, that is, the present invention is not limited to the described embodiments, and covers any modifications, substitutions, and improvements of parts, components, and connection methods without departing from the spirit of the present invention.

[0041] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The following will describe the present application in detail with reference to the accompanying drawings and embodiments.

[0042] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship when the product of the present invention is normally placed, or the orientation or positional relationship commonly understood by those skilled in the art. It is 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 to the present invention.

[0043] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set" and "installed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0044] Figure 1 is a schematic flowchart of a method for establishing a reference coordinate system based on a target device used as a reference benchmark provided by an embodiment of the present invention. The target device includes a base 1, a three-dimensional attitude adjustment mechanism 2, and a reference target 3. The three-dimensional attitude adjustment mechanism 2 is installed on the base 1, and the reference target 3 is fixed to the three-dimensional attitude adjustment mechanism 2; the reference target 3 is made of hard alloy steel and has a cube shape; wherein, as Figure 1 shown, the method includes the following steps:

[0045] S100. Determine the reference coordinate system O S -X S Y S Z S The positive directions of the X S axis, Y S axis, and Z S axis of are the same as the positive directions of the X-axis, Y-axis, and Z-axis of the machine coordinate system O-XYZ of the industrial image measurement system, respectively;

[0046] S200. When the front surface 31 of the reference target is on the object-side focal plane of the industrial camera 5, determine the grating scale reading of the X linear motion axis as the reference coordinate system O S -X S Y S Z S Origin O S of X S0 coordinate component;

[0047] S300. Lock the X-axis and move the industrial camera 5 along the Y-axis direction. When the front edge 35 of the reference target is at the center of the field of view of the industrial camera 5, determine the grating scale reading of the Y linear motion axis as the reference coordinate system O S -X S Y S Z S Origin O S of Y S0 coordinate component;

[0048] S400. Lock the X-axis and move the industrial camera 5 along the Z-axis direction. When the upper edge 34 of the reference target is at the center of the field of view of the industrial camera 5, determine the grating scale reading of the Z linear motion axis as the reference coordinate system O S -X S Y S Z S Origin O S of Z S0 coordinate component;

[0049] S500. Based on the positive directions of the X S axis, Y S axis and Z S axis and the calculated three-dimensional coordinates (X S , Y S0 , Z S0 ) of the origin O S0 , establish the reference coordinate system O S -X S Y S Z S .

[0050] In the above embodiment, in step S100, after the industrial image measurement system returns to zero, set the positive directions of the X S -X S Y S Z S axis, Y S and Z S axis of the reference coordinate system O S to be the same as the positive directions of the X, Y, and Z axes of the machine coordinate system O-XYZ of the industrial image measurement system respectively.

[0051] In step S200, control the X, Y, and Z axes of the industrial image measurement system to drive the industrial camera 5 to move, so that the front surface 31 of the reference target enters the field of view of the industrial camera 5. Set the focusing interval and step length in the X-axis direction, and through the autofocus process, make the industrial camera 5 correctly focus on the front surface 31 of the reference target along the X-axis. At this time, the front surface 31 of the reference target is located on the object-side focal plane of the industrial camera 5, and the industrial camera 5 can collect the sharpest orthographic image of the front surface 31 of the reference target. Record the grating scale readings of the X, Y, and Z linear motion axes of the industrial image measurement system at this time as (X1, Y1, Z1), and calculate the X S coordinate component of O S0 as follows:

[0052] X S0 = X1 (1).

[0053] In step S300, lock the X-axis and move the industrial camera 5 along the positive or negative direction of the Y-axis until the front edge 35 of the reference target appears at the center of the field of view of the industrial camera 5, as Figure 8 shown. Collect the image at this time and record the grating scale readings of the X, Y, and Z linear motion axes at this time as (X2, Y2, Z2) (X2 = X1), and calculate the Y S coordinate component of O S0 as follows:

[0054] Y S0 = Y2 (2).

[0055] In step S400, continue to lock the X-axis and move the industrial camera 5 along the positive direction of the Z-axis until the upper edge 34 of the reference target appears at the center of the field of view of the industrial camera 5, as Figure 9 shown. Collect the image at this time and record the grating scale readings of the X, Y, and Z linear motion axes at this time as (X3, Y3, Z3) (X3 = X1), and calculate the Z S coordinate component of O S0 as follows:

[0056] Z S0 = Z3 (3).

[0057] In step S500, after completing the establishment of the reference coordinate system O S -X S Y S Z S , the mutual conversion relationship between the machine coordinate system O-XYZ and the reference coordinate system O S -X S Y S Z S can be determined, so as to convert the measurement data in the machine coordinate system O-XYZ to the reference coordinate system OS -X S Y S Z S so that, in the case of changing the industrial camera or restarting after shutdown, the relative position relationship between each element can still be restored according to the target device used as the reference benchmark.

[0058] Meanwhile, a plurality of mounting holes 11 are provided at the lower part of the base 1 for fixing and mounting the base 1 on the workbench of the industrial image measurement system by screws. The three-dimensional attitude adjustment mechanism 2 is mounted on the upper end surface of the base 1 by screws. The reference target 3 is mounted and fixed on the three-dimensional attitude adjustment mechanism 2 by clamping or bonding.

[0059] The reference target 3 adopts a specially designed geometric structure feature, having a smooth, flat, and evenly textured matte surface and sharp, continuous, and complete edges, which is convenient for the automatic focusing of the industrial camera 5 and the accurate recognition and extraction of edges, and has the characteristics of simple geometric features, easy processing, and easy guarantee of geometric and dimensional accuracy, and is the best measurement object for the industrial camera 5.

[0060] As an optional implementation manner, each surface of the reference target 3 is a smooth, flat, and evenly textured matte surface.

[0061] Specifically, as Figure 4 shown, the material of the reference target 3 is hard alloy steel or special alloy steel, its shape is a cuboid, having good geometric and dimensional accuracy and surface quality, each surface is a smooth, flat, and evenly textured matte surface, and the flatness error of each surface is not greater than 2 μm. The adjacent surfaces are perpendicular to each other, and the opposite surfaces are parallel to each other. Each edge of the reference target 3 is a sharp, continuous, and complete straight edge, with good straightness, no chamfer, and not being chamfered or dulled. The front surface 31 of the reference target is the surface of the reference target 3 facing the industrial camera 5 in the industrial image measurement system, the upper surface 32 of the reference target is the surface of the reference target 3 facing the positive direction of the Z axis, and the side surface 33 of the reference target is the surface of the reference target 3 facing the positive or negative direction of the Y axis. The upper edge 34 of the reference target is the edge where the front surface 31 of the reference target intersects the upper surface 32 of the reference target, and the front edge 35 of the reference target is the edge where the front surface 31 of the reference target intersects the side surface 33 of the reference target.

[0062] After the target device used as a reference benchmark is installed on the workbench of the industrial image measurement system, auxiliary tools such as a micrometer and an inductive micrometer are applied, and the spatial attitude and orientation of the reference target 3 are adjusted through the three-dimensional attitude adjustment mechanism 2. First, make the front surface 31 of the reference target parallel to the YOZ plane. At this time, the β angle and γ angle of the reference target 3 need to be adjusted, and the adjustment handles 25 of the one-dimensional manual angular position table B22 and the one-dimensional manual rotating table 23 corresponding to it in the attitude adjustment mechanism 2 are adjusted; then, make the upper surface 32 of the reference target parallel to the XOY plane. At this time, the α angle and β angle of the reference target 3 need to be adjusted, and the adjustment handles 25 of the one-dimensional manual angular position table A21 and the one-dimensional manual angular position table B22 corresponding to it in the three-dimensional attitude adjustment mechanism 2 are adjusted. Alternately perform the above steps until the front surface 31 of the reference target is parallel to the YOZ plane and the upper surface 32 of the reference target is parallel to the XOY plane, and tighten each locking nut 24 to fix the state of the three-dimensional attitude adjustment mechanism 2, so that the state of the reference target 3 is fixed and remains unchanged. At this time, the upper edge 34 of the reference target is in the orientation parallel to the Y axis; the front edge 35 of the reference target is in the orientation parallel to the Z axis.

[0063] As an optional implementation manner, the three-dimensional attitude adjustment mechanism 2 includes a one-dimensional manual angular position table A21, a one-dimensional manual angular position table B22, a one-dimensional manual rotating table 23, a plurality of locking nuts 24 and a plurality of adjustment handles 25, and the reference target 3 is installed on the one-dimensional manual rotating table 23;

[0064] The one-dimensional manual angular position table A21 and the one-dimensional manual angular position table B22 are sequentially stacked and installed and are respectively used to adjust the rotation angle α of the reference target 3 around the X axis and the rotation angle β around the Y axis under the drive of the corresponding adjustment handle 25, and the position is locked by the corresponding locking nut 24;

[0065] The one-dimensional manual rotating table 23 is stacked on the one-dimensional manual angular position table A21 or the one-dimensional manual angular position table B22 and is used to adjust the rotation angle γ of the reference target 3 around the Z axis under the drive of the corresponding adjustment handle 25, and the position is locked by the corresponding locking nut 24.

[0066] Specifically, as Figure 3 shown, the one-dimensional manual angular position table A21 and the one-dimensional manual angular position table B22 are stacked and assembled together and the angle adjustment directions are perpendicular to each other, and are respectively used to adjust the rotation angle α of the reference target 3 around the X axis and the rotation angle β around the Y axis, and perform one-dimensional angle position adjustment in the range of -30° to +30° through the adjustment handle 25, and the position is locked by the locking nut 24; the one-dimensional manual rotating table 23 is used to adjust the rotation angle γ of the reference target 3 around the Z axis, and perform one-dimensional angle position adjustment in the range of 0° to 360° through the adjustment handle 25, and the position is locked by the locking nut 24.

[0067] As an alternative embodiment, the target device used as a reference benchmark further includes a protective cover 4, and the protective cover 4 covers the base 1, the three-dimensional attitude adjustment mechanism 2, and the reference target 3.

[0068] Specifically, as Figure 5 shown, the target device used as a reference benchmark is located inside the protective cover 4 and has no contact with each inner surface of the protective cover 4. The protective cover 4 is installed and fixed on the workbench of the industrial image measurement system and is used for dust prevention, collision prevention, impact protection, and protection of the target device used as a reference benchmark. The protective cover 4 is a rectangular parallelepiped hollow housing made of transparent acrylic material to facilitate observation and confirmation of the state of the target device used as a reference benchmark. The protective cover 4 can cover the target device used as a reference benchmark from five directions: above, left, right, front, and rear of the target device used as a reference benchmark. The front surface 41 of the protective cover is the surface of the protective cover 4 between the reference target 3 and the industrial camera 5. A window 411 is provided on the front surface 41 of the protective cover so that the industrial camera 5 can observe the front surface 31 of the reference target, the upper edge 34 of the reference target, and the front edge 35 of the reference target.

[0069] As Figures 6-7 shown, the reference target 3 is used as a reference benchmark in the measurement space of the industrial image measurement system to establish the reference coordinate system O S -X S Y S Z S . The reference coordinate system O S -X S Y S Z S is a right-handed rectangular coordinate system, and the positive directions of the X S , Y S , and Z S axes are respectively the same as the positive directions of the X, Y, and Z axes of the machine coordinate system O-XYZ of the industrial image measurement system. The origin O S is located at the intersection of the upper edge 34 of the reference target and the front edge 35 of the reference target, and its three-dimensional coordinates in the machine coordinate system O-XYZ are (X S0 , Y S0 , Z S0 ).

[0070] It should be clear that each embodiment in this specification is described in a progressive manner. For the same or similar parts between each embodiment, they can be referred to each other. The key point of each embodiment is to illustrate the differences from other embodiments. The present invention is not limited to the specific steps and structures described above and shown in the figures. And, for the sake of brevity, the detailed description of known method technologies is omitted here.

[0071] The above are only the embodiments of the present application and do not limit the present application. For those skilled in the art, various changes and modifications can be made to the present application without departing from the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the scope of the claims of the present application.

Claims

1. A method for establishing a reference coordinate system based on a target device used as a reference benchmark, characterized in that The target device includes a base (1), a three-dimensional attitude adjustment mechanism (2) and a reference target (3). The three-dimensional attitude adjustment mechanism (2) is installed on the base (1), and the reference target (3) is fixed to the three-dimensional attitude adjustment mechanism (2). The reference target (3) is made of hard alloy steel and has a cube shape. Among them, the method includes the following steps: Determine the reference coordinate system O S -X S Y S Z S The positive directions of the X S axis, Y S axis and Z S axis are the same as the positive directions of the X-axis, Y-axis and Z-axis of the machine coordinate system O-XYZ of the industrial image measurement system respectively; Moving industrial camera (5), when the front surface (31) of the reference target is on the object focal plane of the industrial camera (5), determine the grating ruler reading of the X linear motion axis as the reference coordinate system O S -X S Y S Z S Origin O S of the X S0 coordinate component; Lock the X-axis and move the industrial camera (5) along the Y-axis direction. When the front edge (35) of the reference target is at the center of the field of view of the industrial camera (5), determine the grating scale reading of the Y linear motion axis as the Y coordinate component of the reference coordinate system O S -X S Y S Z S Origin O S of the Y S0 coordinate component; Lock the X-axis and move the industrial camera (5) along the Z-axis. When the edge (34) on the reference target is at the center of the field of view of the industrial camera (5), determine the grating scale reading of the Z linear motion axis as the reference coordinate system O S -X S Y S Z S Origin O S of Z S0 coordinate component; According to X S axis, Y S axis and Z S axis positive directions and the calculated origin O S 's three-dimensional coordinates (X S0 , Y S0 , Z S0 ), a reference coordinate system O S -X S Y S Z S ; Each edge of the reference target (3) is a sharp, continuous and complete straight edge. The adjacent surfaces of the reference target (3) are perpendicular to each other, and the opposite surfaces are parallel to each other.

2. The method for establishing a reference coordinate system according to claim 1, wherein Each surface of the reference target (3) is a smooth, flat and evenly textured matte surface.

3. The method for establishing a reference coordinate system according to claim 2, characterized in that The flatness error of each surface of the reference target (3) is ≤2μm.

4. The method for establishing a reference coordinate system according to claim 1, wherein The three-dimensional attitude adjustment mechanism (2) includes a one-dimensional manual angular position table A (21), a one-dimensional manual angular position table B (22), a one-dimensional manual rotary table (23), a plurality of locking nuts (24) and a plurality of adjusting handles (25). The reference target (3) is installed on the one-dimensional manual rotary table (23). The one-dimensional manual angular position table A (21) and the one-dimensional manual angular position table B (22) are stacked and installed in sequence, and are respectively used to adjust the rotation angle α of the reference target (3) around the X-axis and the rotation angle β around the Y-axis under the drive of the corresponding adjusting handle (25), and the position is locked by the corresponding locking nut (24). The one-dimensional manual rotary table (23) is stacked and installed on the one-dimensional manual angular position table A (21) or the one-dimensional manual angular position table B (22), and is used to adjust the rotation angle γ of the reference target (3) around the Z-axis under the drive of the corresponding adjusting handle (25), and the position is locked by the corresponding locking nut (24).

5. The method for establishing a reference coordinate system according to claim 1, characterized in that It further includes a protective cover (4), and the protective cover (4) covers the base (1), the three-dimensional attitude adjustment mechanism (2) and the reference target (3).

6. The method for establishing a reference coordinate system according to claim 5, characterized in that, The protective cover (4) is a transparent cubic hollow shell.

7. The method for establishing a reference coordinate system according to claim 5 or 6, characterized in that, A window (411) is opened on the front surface (41) of the protective cover (4).

8. The method for establishing a reference coordinate system according to claim 5, characterized in that, The protective cover (4) is used to be fixed on the workbench of the industrial image measurement system.

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