Crane support cylinder deformation measurement method and system

Abstract

The application discloses a crane supporting cylinder deformation measurement method and system, and utilizes a projection device to project a supporting cylinder to form mark points, so that mark points of each group of projections are located on the same cross section of the supporting cylinder; mark point images are shot on the periphery of the supporting cylinder to obtain image plane coordinates of all groups of mark points; after the image plane coordinates of the mark points are extracted, the space coordinates of each group of mark points are calculated according to the basic principle of photographic survey, and the space coordinates of any one mark point are calculated by using multiple images; the diameter of the cross section where each group of mark points is located is calculated by using the space coordinates of each group of mark points; and the deformation of the supporting cylinder is calculated according to the diameters of multiple cross sections, and the maximum difference between the diameters is taken as the deformation of the supporting cylinder. The arrangement of the mark points can be completed only by forming the mark points on the same horizontal cross section of the outer surface or the cylindrical surface of the supporting cylinder, and the cost is low.

Description

Technical Field

[0001] This invention belongs to the field of engineering measurement technology, and specifically relates to a method and system for measuring the deformation of a crane support cylinder based on close-range photogrammetry. Background Technology

[0002] Close-range photogrammetry is a highly efficient non-contact measurement method that has been widely applied in industries, construction, and cultural heritage, becoming an important measurement approach. Cranes have tall structures and complex working environments, making it difficult to directly measure key dimensions of their external contours. Traditional measurement methods suffer from poor safety and low efficiency. Close-range photogrammetry can be combined with new technologies such as image processing and computer vision to further improve the accuracy and efficiency of photogrammetry.

[0003] In existing technologies, in addition to conventional contact measurement, the deformation measurement of crane support cylinders also typically uses an infrared transmitter fixed to the lifting machinery for detection. However, the accuracy of the detection results is poor. The receiver and transmitter are exposed to the air, and dust raised in the lifting work area can easily adhere to the receiver and transmitter, causing detection failure and affecting its normal use.

[0004] Meanwhile, existing measurement methods require precise design for the layout of markers, and the methods are relatively complex, with unsatisfactory efficiency and accuracy. Moreover, due to their high cost, they cannot achieve the desired effect for practical engineering use.

[0005] The ability to measure the deformation of a crane support cylinder is of great significance for the practical application of close-range photogrammetry in engineering. Summary of the Invention

[0006] The technical problem to be solved by this application is to provide a simple, efficient, and low-cost method and system for measuring the deformation of a crane support cylinder.

[0007] Furthermore, the present invention also provides a practical non-contact measurement method and system, which has strong applicability and engineering value.

[0008] The embodiments of this application are implemented as follows:

[0009] A method for measuring the deformation of a crane support cylinder, characterized by comprising at least the following steps:

[0010] S1. Use a projection device to project the supporting cylinder to form marker points, so that the marker points of each group of projections are located on the same cross-section of the supporting cylinder; at the same time, determine the shooting distance and select the camera, calibrate the camera, and obtain the camera intrinsic parameters and distortion parameters.

[0011] S2. Select at least two suitable positions (P1, P2, ..., P1) on the outer periphery of the supporting cylinder.i Capture images of the marker points, ensuring that at least one clear image is taken for each location and that all marker points appear in each image. Obtain the image plane coordinates of all groups of marker points.

[0012] S3. After extracting the image plane coordinates of the marker points, calculate the spatial coordinates of each group of marker points according to the basic principles of photogrammetry, and use multiple images to calculate the spatial coordinates of any one of the marker points.

[0013] S4. Calculate the diameter of the cross section where each set of markers is located using the spatial coordinates of each set of markers;

[0014] S5. Calculate the deformation of the supporting cylinder based on the diameters of multiple cross sections, and take the maximum difference between the diameters as the deformation of the supporting cylinder.

[0015] In the above technical solution, in step S1, the markers in the same group are set at a horizontally uniform interval, and multiple groups of markers are set at intervals along the direction of the supporting cylinder.

[0016] In the above technical solution, the distance from each position to the outer surface of the supporting cylinder in step S2 is approximately the same.

[0017] In the above technical solution, all marker points must appear on each image in step S2.

[0018] In the above technical solution, after acquiring the image in step S2, the marker points are extracted and automatically grouped using image processing related technologies: the A group of marker points on the first image is denoted as (A11, A12, ..., A1n), the N group of points on the first image is denoted as (N11, N12, ..., N1n), and the N group of points on the i-th image is denoted as (Ni1, Ni2, ..., Nin).

[0019] In the above technical solution, step S3 calculates the spatial coordinates of each set of marker points based on the collinearity equation between the image plane coordinates and the object space coordinates. The collinearity equation is as follows:

[0020]

[0021] The parameters are as follows:

[0022] In the formula, x and y are the image plane coordinates of the image point; x0, y0, f, and X are the coordinates of the image point. s Y s Z s , ω and κ are interior orientation elements; Δx and Δy are correction values ​​for a certain systematic error, which need to be solved repeatedly during the iteration process; X s Y s Z sThese are three exterior orientation elements on a straight line; X, Y, and Z are the object space coordinates of the object point; a i b i c i (i = 1, 2, 3) are the direction cosines of the three angular orientation elements system;

[0023]

[0024] Among the three types of parameters in the collinearity equation: image point coordinates (x, y), object-space coordinates (X, Y, Z), and interior / exterior orientation elements (x0, y0, f, X). s Y s Z s , In ω, κ), as long as any two types of parameters are known, the third type of parameter can be solved.

[0025] In the above technical solution, step S4 first performs spatial circle or cross-sectional circle fitting on the obtained group of marker points with spatial coordinates, and sets any measurement point Mi(X) in the group. i ,Y i Z i The distance from the center O(X0,Y0,Z0) of the set of spatial circles is

[0026]

[0027] Let the plane P containing the fitted spatial circle be:

[0028] A0X+B0Y+C0Z+D0=0 (3);

[0029] Where A0, B0, C0, and D0 are the coefficients of the plane equation;

[0030] Any measurement point Mi(X) in space i ,Y i Z i The distance from plane P is:

[0031]

[0032] Formula (2) should satisfy |d oi -r|=0, meaning the distance from any point in space to the center O of the spatial circle is equal to the radius r of the spatial circle; formula (4) should satisfy d pi =0, meaning that any point in space lies on plane P;

[0033] Next, construct the objective function:

[0034]

[0035] By minimizing the objective function F, the parameters of the fitted spatial circle or cross-sectional circle, including the radius r and the coordinates of the center O (X0, Y0, Z0), are obtained.

[0036] In the above technical solution, in step S5, the radius of the corresponding spatial circle or cross-sectional circle is calculated for each set of marker points, and the maximum difference in the diameter of multiple cross-sectional circles is taken as the deformation of the support cylinder.

[0037] Based on the above method, the present invention also provides a crane support cylinder deformation measurement system, comprising:

[0038] The projection device projects the support cylinder to form marker points, so that the marker points of each group of projections are located on the same cross-section of the support cylinder.

[0039] The camera should be positioned at at least two suitable locations (P1, P2, ..., P3) around the periphery of the supporting cylinder. i Capture images of the markers, ensuring at least one clear image is taken at each location and all markers appear in each image. Obtain the image plane coordinates of all groups of markers.

[0040] The spatial coordinate calculation unit calculates the spatial coordinates of each group of markers based on the image plane coordinates of the extracted markers and the basic principles of photogrammetry. It also calculates the spatial coordinates of any single marker using multiple images.

[0041] A single-group cross-sectional diameter calculation unit calculates the diameter of the cross-section where each group of markers is located using the spatial coordinates of each group of markers.

[0042] The diameter error calculation unit calculates the deformation of the supporting cylinder based on the diameters of multiple cross-sections, and uses the maximum difference between the diameters as the deformation of the supporting cylinder.

[0043] The aforementioned crane support cylinder deformation measurement system is used to implement the measurement method described above.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] The marker placement method used in this invention is simple and efficient. It only requires forming markers on the same horizontal cross-section of the outer surface of the supporting cylinder or the cylindrical surface to complete the placement of markers, resulting in low cost.

[0046] Multiple sets of markers are set according to accuracy and volume, making them highly adaptable and widely applicable.

[0047] This invention employs close-range photogrammetry, which can instantly record the state of the crane support cylinder without contact, providing a practical and efficient method for measuring the deformation of the crane support cylinder.

[0048] This invention employs spatial circle fitting, which approximates the cross-sectional circle by fitting multiple sets of spatial circles at a height. The turning point and position are determined by the maximum diameter error. This method ensures measurement accuracy while minimizing computational complexity and increasing efficiency.

[0049] The method for determining the deformation of the crane support cylinder proposed in this invention has strong applicability and engineering value. Attached Figure Description

[0050] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 : A schematic diagram of the projection distribution of marker points in the crane support cylinder deformation measurement method based on close-range photogrammetry according to an embodiment of this application;

[0052] Figure 2 : A schematic diagram of the shooting process of the crane support cylinder deformation measurement method based on close-range photogrammetry according to an embodiment of this application;

[0053] Figure 3 : A schematic diagram of the spatial coordinate structure distribution in the crane support cylinder deformation measurement method based on close-range photogrammetry in this application embodiment;

[0054] Figure 4 The following is a schematic diagram of the deformation error of the crane support cylinder based on close-range photogrammetry in the embodiments of this application (Figure a shows the deformation before and after deformation, and Figure b shows the error schematic diagram). Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0056] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0057] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0058] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0059] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0060] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0061] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0062] The features and performance of this application will be further described in detail below with reference to the embodiments.

[0063] Example 1

[0064] Example 1 provides a method for measuring the deformation of a crane support cylinder based on close-range photogrammetry, including the following steps:

[0065] S1. After determining the shooting distance and selecting the camera, calibrate the camera to obtain its intrinsic parameters and distortion parameters. (See attached image) Figure 1 As shown, when projecting onto the outer surface of the supporting cylinder or cylindrical surface 1, the orientation of the projection device should be adjusted so that the projected marker points M are located on the same cross-section, and the center point of each marker point M is marked as 2.

[0066] S2. Select multiple suitable positions (P1, P2, ..., P...). i For the supporting cylinder, take at least one clear image from each position, and acquire a total of two or more images. (See attached image.) Figure 2 As shown, after taking a picture at one position, move to the next position, keeping the distance from each position to the outer surface 1 of the supporting cylinder approximately the same. Obtain the image plane coordinates of the marker points for all groups.

[0067] S3. After extracting the image plane coordinates of the marker points, calculate the spatial coordinates of each group of marker points according to the basic principles of photogrammetry, as shown in the attached figure. Figure 3 As shown, it is denoted as: any marker point M(X) M Y M Z M Each image has a projection (m1, m2, ..., m...). i ), its spatial coordinates (X M Y M Z M All calculations are performed using multiple images.

[0068] S4. Utilize the spatial coordinates (X) of each set of markers. M Y M Z M Calculate the diameter of the cross section where the marker point M is located.

[0069] S5. Calculate the deformation of the supporting cylinder based on the diameters of multiple cross-sections. (See attached diagram) Figure 4 As shown, after the supporting cylinder deforms, the diameter of each cross-section is different, and the maximum difference between the diameters is taken as the deformation of the supporting cylinder.

[0070] Specifically, in S1, the equipment is adjusted so that a set of projected marker points are located on the same cross-section. Multiple sets of marker points M are arranged on the outer surface of the crane support cylinder. The Ath set of points is denoted as (A1, A2, ..., An); the Bth set of points is denoted as (B1, B2, ..., Bn); the Nth set of points is denoted as (N1, N2, ..., Nn); each set has n points.

[0071] Specifically, in S2, after acquiring the image, image processing techniques are used to extract marker points and automatically group them. All marker points must appear on each image. The A-th group of marker points on the first image is denoted as (A11, A12, ..., A1n), the N-th group of points on the first image is denoted as (N11, N12, ..., N1n), and the N-th group of points on the i-th image is denoted as (Ni1, Ni2, ..., Nin).

[0072] Specifically, in S3, the specific implementation of calculating the position of a spatial point using the basic principles of photogrammetry is as follows:

[0073] The collinearity equation expresses the relationship between the image plane coordinates and the object space coordinates. The expression of the collinearity equation is shown in equation (1):

[0074]

[0075] in:

[0076]

[0077] In the formula, x and y are the image plane coordinates of the image point; x0, y0, and f are interior orientation elements; Δx and Δy are correction values ​​for a certain systematic error, which need to be solved repeatedly during the iteration process; X s Y s Z s These are three exterior orientation elements on a straight line; X, Y, and Z are the object space coordinates of the object point; a i b i c i (i = 1, 2, 3) is the direction cosine of the three angular orientation elements system.

[0078] The collinearity equation has three types of parameters: image point coordinates (x, y), object-space coordinates (X, Y, Z), and interior / exterior orientation elements (x0, y0, f, X). s Y s Z s , In the equation (ω, κ), the third type of parameter can be solved as long as any two types of parameters are known.

[0079] Specifically, in S4, the implementation of calculating the diameter of the cross-section where each set of markers is located is as follows:

[0080] The points used for fitting are all spatial points obtained in S3, and any measurement point Mi(X) in space. i ,Y i Z i The distance from the center O(X0,Y0,Z0) to the center O(X0,Y0,Z0) is:

[0081]

[0082] The plane P containing the fitted spatial circle is:

[0083] A0X+B0Y+C0Z+D0=0 (3)

[0084] Where A0, B0, C0, and D0 are the coefficients of the plane equation.

[0085] Any measurement point Mi(X) in space i ,Y i Z i The distance from plane P is:

[0086]

[0087] Formula (2) should satisfy |d oi -r|=0, meaning the distance from any point in space to the center of the circle is equal to the radius. Formula (4) should satisfy d pi =0, meaning that any point in space lies on the plane.

[0088] Since there will inevitably be some error, the objective function is constructed as follows:

[0089]

[0090] By minimizing the objective function F, the parameters of the fitted spatial circle, including the radius r and the coordinates of the center O (X0, Y0, Z0), are obtained.

[0091] Specifically, in S5, the specific implementation of calculating the deformation of the supporting cylinder based on the radius is as follows:

[0092] For each set of markers, the radius of the corresponding cross-section can be calculated, and the radii are respectively (r a r b , ..., r n The maximum difference in diameter among multiple cross-sections is taken as the deformation Δd of the supporting cylinder.

[0093] Δd=2(max(r a ,r b ,...r n )-min(r a ,r b ,...,r n )).

[0094] Example 2:

[0095] Based on the above method, the present invention also provides a crane support cylinder deformation measurement system, comprising:

[0096] The projection device projects onto the outer surface of the supporting cylinder or cylindrical surface 1, forming a marker point M, such that the marker points of each group of projections are located on the same horizontal cross-section of the outer surface of the supporting cylinder or cylindrical surface 1; thus forming multiple groups of projection marker points.

[0097] The camera should be positioned at at least two suitable locations (P1, P2, ..., P3) around the periphery of the supporting cylinder. i Capture images of the markers, ensuring at least one clear image is taken at each location and all markers appear in each image. Obtain the image plane coordinates of all groups of markers.

[0098] The spatial coordinate calculation unit calculates the spatial coordinates of each group of markers based on the image plane coordinates of the extracted markers and the basic principles of photogrammetry. It also calculates the spatial coordinates of any single marker using multiple images.

[0099] A single-group cross-sectional diameter calculation unit calculates the diameter of the cross-section where each group of markers is located using the spatial coordinates of each group of markers.

[0100] The diameter error calculation unit calculates the deformation of the supporting cylinder based on the diameters of multiple cross-sections, and uses the maximum difference between the diameters as the deformation of the supporting cylinder.

[0101] The aforementioned crane support cylinder deformation measurement system is used to implement the measurement method described above.

[0102] The embodiments described above are some, but not all, of the embodiments of this application. The detailed description of the embodiments of this application is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

Claims

1. A method for measuring the deformation of a crane support cylinder, characterized in that... It should include at least the following steps: S1. Project the supporting cylinder using a projection device to form marker points, so that the marker points of each group of projections are located on the same cross-section of the supporting cylinder; the marker points in the same group are set at a horizontal and uniform interval, and multiple groups of marker points are set at intervals along the direction of the supporting cylinder. S2. Select at least two suitable positions on the periphery of the supporting cylinder to take images of the marker points. Take at least one clear image at each position, and all marker points must appear in each image. Obtain the image plane coordinates of all groups of marker points. S3. After extracting the image plane coordinates of the marker points, calculate the spatial coordinates of each group of marker points according to the basic principles of photogrammetry, and use multiple images to calculate the spatial coordinates of any one marker point. S4. Calculate the diameter of the cross section where each set of markers is located using the spatial coordinates of each set of markers; S5. Using spatial circle fitting, the deformation of the supporting cylinder is calculated based on the diameters of multiple cross-sections, and the maximum difference between the diameters is taken as the deformation of the supporting cylinder.

2. The method for measuring the deformation of a crane support cylinder according to claim 1, characterized in that... In step S2, the distance from each position to the outer surface of the supporting cylinder is approximately the same.

3. The method for measuring the deformation of a crane support cylinder according to claim 1, characterized in that... After acquiring the image in step S2, the marker points are extracted and automatically grouped using image processing techniques.

4. The method for measuring the deformation of a crane support cylinder according to claim 1, characterized in that... In step S3, the spatial coordinates of each set of marker points are calculated based on the collinearity equation between the image plane coordinates and the object space coordinates. Among the three types of parameters in the collinearity equation: image point coordinates ( , ), object space coordinates of object point ( X,Y,Z ) and internal and external orientation elements In this method, as long as any two types of parameters are known, the third type of parameter can be solved.

5. The method for measuring the deformation of a crane support cylinder according to claim 1, characterized in that... In step S4, the obtained marker points in the same group with spatial coordinates are first fitted with a spatial circle or a cross-sectional circle, and any measurement point in the group is set. M i (X i ,Y i ,Z i ) To the center O of this set of spatial circles (X 0 ,Y 0 ,Z 0 ) The distance is: ； Let the plane P containing the fitted spatial circle be: ； in, A 0 ，B 0 ，C 0 ，D 0 represents the coefficients of the plane equation; Any measurement point in space M i (X i ,Y i ,Z i ) The distance to plane P is: ； In the above formula, That is, the distance from any point in space to the center O of the spatial circle is equal to the radius of the spatial circle. r ; That is, any point in space lies on plane P; Next, construct the objective function: ； By minimizing the objective function F, the parameters of the fitted spatial circle or cross-sectional circle, including the radius, can be obtained. r Coordinates of the center O (X 0 ,Y 0 ,Z 0 ) .

6. The method for measuring the deformation of a crane support cylinder according to claim 1, characterized in that... In step S5, the radius of the corresponding spatial circle or cross-sectional circle is calculated for each set of marker points, and the maximum difference in the diameter of multiple cross-sectional circles is taken as the deformation of the support cylinder.

7. A crane support cylinder deformation measurement system, comprising: The projection device projects the support cylinder to form marker points, so that the marker points of each group of projections are located on the same cross-section of the support cylinder. The markers in the same group are set at even horizontal intervals, and multiple groups of markers are set at intervals along the direction of the supporting cylinder. The camera is used to take pictures of the marker points at at least two suitable positions around the support cylinder. At least one clear image is taken at each position and all marker points must appear in each image. The image plane coordinates of all groups of marker points are obtained. The spatial coordinate calculation unit calculates the spatial coordinates of each group of markers based on the image plane coordinates of the extracted markers and the basic principles of photogrammetry. It can also calculate the spatial coordinates of any single marker using multiple images. A single-group cross-sectional diameter calculation unit calculates the diameter of the cross-section where each group of markers is located using the spatial coordinates of each group of markers. The diameter error calculation unit uses spatial circle fitting to calculate the deformation of the supporting cylinder based on the diameters of multiple cross-sections, and uses the maximum difference between the diameters as the deformation of the supporting cylinder.

8. A crane support cylinder deformation measurement system for implementing the measurement method described in any one of claims 1-6.

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