Design method of omni-directional speckle structured light measuring system for three-dimensional measurement of wellbore casing

Abstract

The present application belongs to the technical field of oil and gas equipment detection, and particularly relates to a design method of an omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement. The design method of the omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement realizes high-precision and high-efficiency reconstruction of the full-circumferential three-dimensional morphology of the casing cavity, effectively overcoming the defects of the existing wellbore casing detection system, such as insufficient theoretical basis for parameter design and inability to reconstruct the full-circumferential morphology from a single image. The design method of the omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement comprises the following steps: constructing a light path model of the omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement; calculating the projection range and imaging range of the light path model of the omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement; and optimizing the parameters of the light path model of the omnidirectional speckle structured light measuring system for wellbore casing three-dimensional measurement.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas equipment testing technology, and particularly relates to the design method of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. Background Technology

[0002] In oil drilling operations, the well casing serves as a support for the wellbore and prevents collapse, making it a crucial structure for ensuring the smooth implementation of drilling and subsequent oil production operations. However, during service, the well casing not only suffers wear due to friction with downhole tools or rock formations, but also endures harsh conditions such as high temperature, high pressure, complex stress, and electrochemical corrosion, leading to accelerated wear and even extreme situations like deformation, diameter reduction, and perforation. Therefore, to ensure the long-term stable operation of oil and gas wells and reduce frequent well workovers caused by casing wear, technicians need to conduct regular inspections of the well casing to assess for any potential safety hazards.

[0003] Further research revealed that existing well casing inspection systems typically use point and line structured light, combined with a rotating mechanism, to complete a full circumferential scan of the well casing, thereby acquiring cavity morphology data. However, this type of well casing inspection system requires coordinated rotation and feeding, making it impossible to obtain all data images of the cavity data reconstruction process through a single motion, resulting in low work efficiency and susceptibility to motion errors. For example, the patent CN115170671B, "Calibration Method, System, and Calibration Device for Omnidirectional Loop 3D Scanner," proposes a calibration method, system, and device. However, this technical solution cannot achieve omnidirectional reconstruction from a single image, but relies on stitching together multiple frames, thus affecting reconstruction accuracy; moreover, its system structure is complex, and key parameters lack theoretical derivation, limiting its applicability to various inspection scenarios. The patent CN216621031U, "An Omnidirectional 3D Scanning System," proposes an omnidirectional visual stereo device, specifically comprising multiple omnidirectional visual sensors. However, it is worth noting that this technical solution does not establish a mathematical relationship between optical element parameters and imaging range, and the parameter design lacks theoretical support.

[0004] In summary, existing well casing inspection systems still have significant limitations in achieving omnidirectional reconstruction of the well casing cavity. Therefore, there is an urgent need for those skilled in the art to provide a novel design method for designing a three-dimensional measurement system for well casing to meet the requirements for detecting three-dimensional morphological data of the well casing cavity. Summary of the Invention

[0005] This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. Specifically, this design method creates a novel omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing based on stacked hyperboloid mirrors. This system achieves high-precision and efficient reconstruction of the full-circumference three-dimensional morphology of the casing cavity, effectively overcoming the shortcomings of existing well casing inspection systems, such as insufficient theoretical basis for parameter design and the inability to reconstruct the full-circumference morphology from a single image.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] The design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing includes the following steps:

[0008] Step S1: Construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing;

[0009] Step S2: Calculate the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing;

[0010] Step S3: Optimize the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0011] Preferably, the process of constructing the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S1 is specifically described as follows:

[0012] In the XOZ plane, construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing;

[0013] A coordinate system is established with one focal point of the hyperboloid mirror in the omnidirectional speckle structured light measurement system as the origin. The standard equation of the hyperboloid mirror satisfies: (1);

[0014] focal length of a hyperboloid mirror ,satisfy: ;

[0015] Assuming the diameter of the hyperboloid mirror is d, and the distance between the optical center of the camera and the bottom of the hyperboloid mirror is h, what is the maximum field of view in the vertical direction of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing? For the focus The angle between the ray emanating from point P on the edge of the hyperboloid mirror and the Z-axis satisfies: (2);

[0016] Combining equations (1) and (2), we obtain the mathematical expressions for the parameters a and b of the hyperboloid mirror, which satisfy: (3).

[0017] The preferred step, S2, involves calculating the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional well casing measurement. The specific description is as follows:

[0018] In the XOZ plane, the origin O is taken as the midpoint of the line connecting the two focal points of the projection hyperboloid mirror in the hyperboloid mirror, the axis of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is taken as the Z-axis, and the inner diameter direction of the cavity is taken as the X-axis.

[0019] Using the focal point outside the projection hyperboloid mirror as the projector's optical center, and the focal point outside the imaging hyperboloid mirror as the camera's optical center, with the distance s between the interior focal points of the projection and imaging hyperboloid mirrors, the mathematical expression for the projection hyperboloid mirror is calculated, satisfying: (4); The mathematical expression for the imaging hyperboloid mirror satisfies: (5);

[0020] in, The surface parameters of the projected hyperboloid mirror, For the surface shape parameters of the imaging hyperboloid mirror, These are the focal lengths of the projection hyperboloid mirror and the imaging hyperboloid mirror, respectively; the optical center of the projector. The coordinates are Camera optical center The coordinates are ;

[0021] Assume the projector's projection angle is Then the direction vector of the outgoing light rays at the edge of the speckle pattern satisfies: ;

[0022] The ray path satisfies: (6);

[0023] After further decomposition, we get: (7); where, parameter Indicates the distance that light travels;

[0024] Substituting equations (6) and (7) into equation (4), we obtain the parameters. The quadratic equation satisfies: (8);

[0025] in: (9);

[0026] Solving for the parameters ,satisfy: (10);

[0027] Get parameters The maximum positive root is used to find the coordinates of the reflection point, which satisfy: The direction vector of the reflected ray satisfies: ;

[0028] Further calculations yielded the coordinates of the projection point of the reflected ray at the cavity of radius R, which are the coordinates of the upper edge of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. ;

[0029] Let the projection angle of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing be . The direction vector of the light rays reflected from the top edge of the projected hyperboloid mirror satisfies: ;in, It is a rotation matrix;

[0030] Direction vector Substitute the parametric equations and repeat the above steps to calculate the coordinates of the reflection point. The coordinates of the lower edge point of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. ;

[0031] in, The distance between the two points is the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing onto a cavity with radius R.

[0032] The preferred step S2, which involves calculating the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, is specifically described as follows:

[0033] Assuming the maximum imaging field of view of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is The camera's field of view is Then the distance between the focal point of the hyperboloid mirror inside the mirror and the optical center of the camera can be calculated. ,satisfy: (11);

[0034] in, Let the diameter of the hyperboloid mirror satisfy: ;

[0035] Further calculations yielded the surface shape parameters of the imaging hyperboloid mirror. Based on the surface shape parameters of the imaging hyperboloid mirror. Obtain another reflection point of the imaging hyperboloid mirror And the upper edge point of the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. , lower edge point ;

[0036] in, The area between the two points is the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing on a cavity with radius R.

[0037] Preferably, the process of optimizing the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S3 is specifically described as follows:

[0038] Quantify the effective measurement area;

[0039] Assume the ratio of the overlapping region k1 of the projection range and the merging region k2 of the projection range and the imaging range is k;

[0040] Among them, the overlapping region k1, the merged region k2, and the ratio k satisfy: (12);

[0041] Let be the upper edge point, satisfying: ; Let be the lower edge point, satisfying: ;

[0042] When there is no overlapping region, i.e. ,count ;

[0043] The objective function for optimizing the optical path model parameters of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is constructed, resulting in: (13);

[0044] Among them, the parameter optimization objective Ω contains .

[0045] This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The design method includes the following steps: Step S1: Constructing the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S2: Calculating the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S3: Optimizing the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0046] The design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, which has the above-mentioned step characteristics, has at least the following technical advantages compared with the prior art:

[0047] 1) This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The method utilizes the Levenberg-Marquardt (LM) algorithm to optimize the parameters of the optical path model. The LM algorithm is a nonlinear optimization algorithm for solving least-squares problems. By combining gradient descent and Gauss-Newton methods, it achieves dynamic adjustment of damping parameters. While ensuring convergence speed, it avoids ill-conditioned problems that may occur when the initial point is poorly chosen, and can be widely applied to curve fitting and parameter estimation.

[0048] 2) The present invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The optical path model of the omnidirectional speckle structured light measurement system is constructed, and the projection range and imaging range of the constructed omnidirectional speckle structured light measurement system almost completely overlap. The layout of each component is clarified and optimization parameters are given, realizing high-precision reconstruction of a single three-dimensional point cloud image of the entire circumference of the well casing cavity. It is especially suitable for well casing cavity inspection scenarios with high requirements for both measurement efficiency and measurement accuracy. Attached Figure Description

[0049] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the following drawings:

[0050] Figure 1 This is a flowchart illustrating the design method of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing provided by the present invention.

[0051] Figure 2a This is a schematic diagram of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, corresponding to the optical path model.

[0052] Figure 2b for Figure 2a The diagram shows the structure of the projection hyperboloid mirror and the imaging hyperboloid mirror in the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0053] Figure 3 This is a schematic diagram of the optical path corresponding to the optical path model.

[0054] Reference numerals: 1. Projector; 2. Camera; 3. Hyperboloid mirror; 31. Projection hyperboloid mirror; 32. Imaging hyperboloid mirror; 4. Support. Detailed Implementation

[0055] This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. Specifically, this design method creates a novel omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing based on stacked hyperboloid mirrors. This system achieves high-precision and efficient reconstruction of the full-circumference three-dimensional morphology of the casing cavity, effectively overcoming the shortcomings of existing well casing inspection systems, such as insufficient theoretical basis for parameter design and the inability to reconstruct the full-circumference morphology from a single image.

[0056] like Figure 1 As shown, this invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, which specifically includes the following steps:

[0057] Step S1: Construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0058] To facilitate understanding of the present invention by those skilled in the art, the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, designed using the method of the present invention, is further described as follows: The composition of each structural unit can be referenced as follows: Figure 2a , Figure 2b As shown. Specifically, the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing includes a projector 1, a camera 2, a hyperboloid mirror 3, a support 4, a well casing specimen 5 to be measured, and a fixture 6. Further, the projector 1 and the projection hyperboloid mirror 31 constitute the projection part, the camera 2 and the imaging hyperboloid mirror 32 constitute the imaging part, and the fixture 6 is used to ensure that the projection part and the imaging part are placed in the same direction and on the same axis.

[0059] In addition, see references such as Figure 3 As shown, Figure 3 This diagram illustrates the optical path of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. Figure 3 It includes the focal point of the projection hyperboloid mirror, the imaging hyperboloid mirror, and... , etc. angles, and , , , By using edge points, the projection range and imaging range are clearly presented.

[0060] As a preferred embodiment of the present invention, the process of constructing the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S1 is specifically described as follows:

[0061] In the XOZ plane, construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0062] A coordinate system is established with one focal point of the hyperboloid mirror in the omnidirectional speckle structured light measurement system as the origin. The standard equation of the hyperboloid mirror satisfies: (1).

[0063] focal length of a hyperboloid mirror ,satisfy: .

[0064] Assuming the diameter of the hyperboloid mirror is d, and the distance between the optical center of the camera and the bottom of the hyperboloid mirror is h, what is the maximum field of view in the vertical direction of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing? For the focus The angle between the ray emanating from point P on the edge of the hyperboloid mirror and the Z-axis satisfies: (2).

[0065] Combining equations (1) and (2), we obtain the mathematical expressions for the parameters a and b of the hyperboloid mirror, which satisfy: (3).

[0066] To simplify the subsequent calculation process, the relevant parameters are initially set as follows: Then, by inputting the parameters d and h of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, as well as the maximum field of view required in the vertical direction... The surface parameters a and b of the hyperboloid mirror can be calculated using equation (3).

[0067] Step S2: Calculate the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0068] Based on completing step S1, further implement step S2. Specifically, step S2 is used to calculate the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0069] In a preferred embodiment of the present invention, the process of calculating the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S2 is specifically described as follows:

[0070] First, in the XOZ plane, take the midpoint of the line connecting the two focal points of the projected hyperboloid mirror in the hyperboloid mirror as the origin O, the axis of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing as the Z-axis, and the inner diameter direction of the cavity as the X-axis to establish a coordinate system.

[0071] Using the focal point outside the projection hyperboloid mirror as the projector's optical center, and the focal point outside the imaging hyperboloid mirror as the camera's optical center, with the distance s between the interior focal points of the projection and imaging hyperboloid mirrors, the mathematical expression for the projection hyperboloid mirror is calculated, satisfying: (4); The mathematical expression for the imaging hyperboloid mirror satisfies: (5).

[0072] in, The surface parameters of the projected hyperboloid mirror, For the surface shape parameters of the imaging hyperboloid mirror, These are the focal lengths of the projection hyperboloid mirror and the imaging hyperboloid mirror, respectively; the optical center of the projector. The coordinates are Camera optical center The coordinates are .

[0073] Specifically, based on the aforementioned preset parameters, the surface shape parameters of the projected hyperboloid mirror are... Specifically ,focal length Specifically, it is 100. At this point, the optical center of the projector is obtained. With camera optical center The coordinates are respectively and .

[0074] Assume the projector's projection angle is Then the direction vector of the outgoing light rays at the edge of the speckle pattern satisfies: .

[0075] The ray path satisfies: (6);

[0076] After further decomposition, we get: (7); where, parameter It indicates the distance that light travels.

[0077] Substituting equations (6) and (7) into equation (4), we obtain the parameters. The quadratic equation satisfies: (8);

[0078] in: (9)

[0079] Solving for the parameters ,satisfy: (10).

[0080] Get parameters The maximum positive root is used to find the coordinates of the reflection point, which satisfy: The direction vector of the reflected ray satisfies: .

[0081] Specifically, assuming the projector's projection angle is... The direction vector of the outgoing light rays at the edge of the speckle pattern is specifically expressed as: The ray path is represented as: At this point, retrieve the parameters. The largest positive root yields the coordinates of the reflection point. The direction vector of the reflected ray is Its parametric equations are constructed through focus F1.

[0082] Further calculations yielded the coordinates of the projection point of the reflected ray at the cavity of radius R, which are the coordinates of the upper edge of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. .

[0083] Then, let the projection angle of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing be . The direction vector of the light rays reflected from the top edge of the projected hyperboloid mirror satisfies: ;in, It is a rotation matrix.

[0084] Specifically, the angle of projection choose The direction vector of the light ray reflected from the top edge of the projected hyperboloid mirror is then... The rotation matrix is ​​specifically... .

[0085] Direction vector Substituting the parametric equations and repeating the above steps, the coordinates of the reflection point can be calculated. The coordinates of the lower edge point of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. .

[0086] in, The distance between the two points is the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing onto a cavity with radius R.

[0087] Furthermore, as another preferred embodiment of the present invention, the process of calculating the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S2 is specifically described as follows:

[0088] Assuming the maximum imaging field of view of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is... The camera's field of view is Then the distance between the focal point of the hyperboloid mirror inside the mirror and the optical center of the camera can be calculated. ,satisfy: (11);

[0089] in, Let the diameter of the hyperboloid mirror satisfy: .

[0090] Then, further calculations were performed to obtain the surface shape parameters of the imaging hyperboloid mirror. Based on the surface shape parameters of the imaging hyperboloid mirror. Obtain another reflection point of the imaging hyperboloid mirror And the upper edge point of the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. , lower edge point .

[0091] in, The area between the two points is the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing on a cavity with radius R.

[0092] Thus, the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing have been calculated, and the coordinates of the upper edge point of the projection range have been obtained accordingly. Coordinates of the lower edge point of the projection range and the upper edge point of the imaging range. With the lower edge point .

[0093] Step S3: Optimize the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0094] Based on completing step S2, step S3 is further implemented. Specifically, in a preferred embodiment of the present invention, the process of optimizing the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S3 is described as follows:

[0095] First, the effective measurement area is quantified.

[0096] Assume the ratio of the overlapping region k1 of the projection range and the merging region k2 of the projection range and the imaging range is k. It is worth noting that for a ratio of k, when k=1, it means that the speckle pattern and imaging pixels are fully utilized, which corresponds to the optimal system parameters.

[0097] Based on this, the ratio k between the overlapping region k1 of the projection range and the merging region k2 of the projection range and the imaging range is calculated and statistically analyzed. Specifically, the overlapping region k1, the merging region k2, and the ratio k satisfy the following: (12);

[0098] in, Let be the upper edge point, satisfying: ; Let be the lower edge point, satisfying: .

[0099] When there is no overlapping region, i.e. ,count .

[0100] Therefore, the objective function for optimizing the optical path model parameters of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is obtained as follows: (13);

[0101] Among them, the parameter optimization objective Ω contains .

[0102] It is worth noting that, as an alternative implementation, the Levenberg-Marquardt (LM) algorithm is used here for optimization of the aforementioned parameters. This method is a nonlinear optimization algorithm for solving least squares problems, combining gradient descent and the Gauss-Newton method. By dynamically adjusting the damping parameters, it ensures convergence speed while avoiding ill-conditioned problems that may occur when the initial point is poorly chosen. Therefore, it can be widely applied to curve fitting and parameter estimation problems.

[0103] Specifically, the optimal parameter statistics obtained after optimizing the parameters set in the initial values ​​are shown in the table below:

[0104] ;

[0105] This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The design method includes the following steps: Step S1: Constructing the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S2: Calculating the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S3: Optimizing the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing.

[0106] The design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, which has the above-mentioned step characteristics, has at least the following technical advantages compared with the prior art:

[0107] 1) This invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The method utilizes the Levenberg-Marquardt (LM) algorithm to optimize the parameters of the optical path model. The LM algorithm is a nonlinear optimization algorithm for solving least-squares problems. By combining gradient descent and Gauss-Newton methods, it achieves dynamic adjustment of damping parameters. While ensuring convergence speed, it avoids ill-conditioned problems that may occur when the initial point is poorly chosen, and can be widely applied to curve fitting and parameter estimation.

[0108] 2) The present invention provides a design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. The optical path model of the omnidirectional speckle structured light measurement system is constructed, and the projection range and imaging range of the constructed omnidirectional speckle structured light measurement system almost completely overlap. The layout of each component is clarified and optimization parameters are given, realizing high-precision reconstruction of a single three-dimensional point cloud image of the entire circumference of the well casing cavity. It is especially suitable for well casing cavity inspection scenarios with high requirements for both measurement efficiency and measurement accuracy.

[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A design method for an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, characterized in that, The steps include the following: Step S1: Construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S2: Calculate the projection range and imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; Step S3: Optimize the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; The process of constructing the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S1 is specifically described as follows: In the XOZ plane, construct the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing; A coordinate system is established with one focal point of the hyperboloid mirror in the omnidirectional speckle structured light measurement system as the origin; the standard equation of the hyperboloid mirror satisfies: （1）； The focal length c of the hyperboloid mirror satisfies: ; Assuming the diameter of the hyperboloid mirror is d, and the distance between the optical center of the camera and the bottom of the hyperboloid mirror is h, what is the maximum field of view in the vertical direction of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing? For the focus The angle between the ray emanating from point P on the edge of the hyperboloid mirror and the Z-axis satisfies: （2）； Combining equations (1) and (2), we obtain the mathematical expressions for the parameters a and b of the hyperboloid mirror, which satisfy: （3） 。 2. The design method of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing according to claim 1, characterized in that, Step S2, which calculates the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, is specifically described as follows: In the XOZ plane, the origin O is taken as the midpoint of the line connecting the two focal points of the projection hyperboloid mirror in the hyperboloid mirror, the axis of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is taken as the Z-axis, and the inner diameter direction of the cavity is taken as the X-axis. Using the focal point outside the projection hyperboloid mirror as the projector's optical center, and the focal point outside the imaging hyperboloid mirror as the camera's optical center, with the distance s between the interior focal points of the projection and imaging hyperboloid mirrors, the mathematical expression for the projection hyperboloid mirror is calculated, satisfying: (4); The mathematical expression for the imaging hyperboloid mirror satisfies: （5）； in, The surface parameters of the projected hyperboloid mirror, For the surface shape parameters of the imaging hyperboloid mirror, These are the focal lengths of the projection hyperboloid mirror and the imaging hyperboloid mirror, respectively; the optical center of the projector. The coordinates are Camera optical center The coordinates are ; Assume the projector's projection angle is Then the direction vector of the outgoing light rays at the edge of the speckle pattern satisfies: ； The ray path satisfies: （6） ； After further decomposition, we get: (7); where, parameter Indicates the distance that light travels; Substituting equations (6) and (7) into equation (4), we obtain the parameters. The quadratic equation satisfies: （8）； in: (9); Solving for the parameters ,satisfy: （10）； Get parameters The maximum positive root is used to find the coordinates of the reflection point, which satisfy: The direction vector of the reflected ray satisfies: ; Further calculations yielded the coordinates of the projection point of the reflected ray at the cavity of radius R, which are the coordinates of the upper edge of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. ; Let the projection angle of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing be . The direction vector of the light rays reflected from the top edge of the projected hyperboloid mirror satisfies: ;in, It is a rotation matrix; Direction vector Substitute the parametric equations and repeat the above steps to calculate the coordinates of the reflection point. The coordinates of the lower edge point of the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. ; in, The distance between the two points is the projection range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing onto a cavity with radius R.

3. The design method of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing according to claim 1, characterized in that, Step S2, which calculates the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing, is specifically described as follows: Assuming the maximum imaging field of view of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is The camera's field of view is Then the distance between the focal point of the hyperboloid mirror inside the mirror and the optical center of the camera can be calculated. ,satisfy: （11）； in, Let the diameter of the hyperboloid mirror satisfy: ; Further calculations yielded the surface shape parameters of the imaging hyperboloid mirror. Based on the surface shape parameters of the imaging hyperboloid mirror. Obtain another reflection point of the imaging hyperboloid mirror And the upper edge point of the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing. , lower edge point ; in, The area between the two points is the imaging range of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing on a cavity with radius R.

4. The design method of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing according to claim 1, characterized in that, The process of optimizing the parameters of the optical path model of the omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing in step S3 is specifically described as follows: Quantify the effective measurement area; Assume the ratio of the overlapping region k1 of the projection range and the merging region k2 of the projection range and the imaging range is k; Among them, the overlapping region k1, the merged region k2, and the ratio k satisfy: （12）； Let be the upper edge point, satisfying: ; Let be the lower edge point, satisfying: ; When there is no overlapping region, i.e. ,count ; The objective function for optimizing the optical path model parameters of an omnidirectional speckle structured light measurement system for three-dimensional measurement of well casing is constructed, resulting in: （13） ； Among them, the parameter optimization objective Ω contains .

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