Method for accurately measuring and evaluating shape, position and size of ultra-long large-thickness common-bottom storage tank

Abstract

The invention provides a method for accurately measuring and evaluating the shape, position and size of an ultra-long and large-thickness common-bottom storage box, and the method comprises the steps: carrying out the segmented scanning of the ultra-long and large-thickness common-bottom storage box, and arranging a plurality of common measurement points in each scanning segment; a laser tracker is adopted to measure the coordinates of all the common measuring points under the global coordinate system, and a set of the common measuring points under the global coordinates is obtained; local measuring points are arranged in the measuring sections, key features of all the sections are scanned through a laser scanner, and feature scanning point clouds of the sections are converted into point clouds under a global coordinate system; integrating the section scanning point clouds under the global coordinate system to obtain an overall scanning point cloud, obtaining a pose set of the key features of the storage tank under the action of gravity, and performing gravity deformation simulation calculation of the storage tank to obtain poses of the key features of the storage tank under a simulation coordinate system; and according to a simulation deformation result, compensating a feature pose obtained by horizontal scanning measurement to obtain the shape and position size of the ultra-long and large-thickness common-bottom storage tank without gravity influence.

Description

Technical Field

[0001] The present invention relates to the technical field of the measurement and evaluation of the shape and position dimensions of rocket tanks. Specifically, it relates to a method for accurately measuring and evaluating the shape and position dimensions of an ultra-long and thick co-bottom tank. Background Art

[0002] As the main load-bearing structure of a new generation of launch vehicles, the manufacturing accuracy of an ultra-long and thick co-bottom tank directly affects the service performance of the launch vehicle. To ensure the flight attitude of the rocket body and the machining accuracy of the conduit installation brackets, it is necessary to accurately measure and evaluate the key shape and position dimensions (such as cross-sectional perimeter, roundness, coaxiality, overall surface difference, etc.) of the ultra-long and thick co-bottom tank and the installation profile and position of the conduit brackets on the tank in a horizontal state.

[0003] However, the traditional laser tracker measurement method is difficult to meet the field measurement requirements for the overall shape and local fine features of the tank. On the other hand, in order to measure the overall shape and local fine features of the tank within an ultra-long span, the traditional laser scanner profile measurement method requires a large number of station transfers and splicing, which will introduce a large number of splicing errors and cause large measurement errors in the shape and position dimensions of the tank. In addition, the ultra-long and thick co-bottom tank weighs more than 20 tons, and significant self-weight deformation will occur when placed horizontally, resulting in the measurement results in the horizontal state being unable to reflect the true shape of the tank during the vertical assembly of the rocket body. Therefore, it is necessary to propose a new method for accurately measuring and evaluating the shape and position dimensions according to the structural characteristics and stress state of the ultra-long and thick co-bottom tank. Summary of the Invention

[0004] Aiming at the defects in the prior art, the purpose of the present invention is to provide a method for accurately measuring and evaluating the shape and position dimensions of an ultra-long and thick co-bottom tank, which is used to solve the problem that it is difficult to accurately measure and evaluate the shape and position dimensions of the ultra-long and thick co-bottom tank due to long span and self-weight deformation.

[0005] To solve the above problems, the technical solution of the present invention is as follows:

[0006] A method for accurately measuring and evaluating the shape and position dimensions of an ultra-long and thick co-bottom tank, comprising the following steps:

[0007] Segmentally scan the ultra-long and thick co-bottom tank, and arrange a plurality of common measurement points in each scanned segment;

[0008] Use a laser tracker to measure the coordinates of all common measurement points in the global coordinate system, and obtain the set of common measurement points in the global coordinates;

[0009] Local measurement points are arranged in the measurement section, and the key features of each section are scanned by a laser scanner to obtain the section feature point cloud and the coordinate information of the section common measurement points in the local coordinates of the laser scanner, and the feature scan point cloud of the section is transformed into the point cloud in the global coordinate system;

[0010] The overall scan point cloud is obtained by integrating the section scan point clouds in the global coordinate system, and the pose set of the key features of the storage tank under the action of gravity is obtained, and the gravity deformation simulation calculation of the storage tank is carried out to obtain the pose of the key features of the storage tank in the simulation coordinate system;

[0011] According to the simulation deformation results, the feature poses obtained by horizontal scan measurement are compensated to obtain the geometric dimensions of the ultra-long and thick-bottom storage tank without the influence of gravity.

[0012] Preferably, in the step of segmentally scanning the ultra-long and thick-bottom storage tank and arranging a plurality of common measurement points in each scan section, the scan sections are divided according to the relative position relationship of the key features of the storage tank structure, and the features with relatively high scan accuracy requirements for each other's poses are divided into the same scan section to obtain N storage tank scan sections, and a plurality of common measurement points are arranged in each scan section.

[0013] Preferably, the step of measuring the coordinates of all common measurement points in the global coordinate system by using a laser tracker to obtain the set of common measurement points in the global coordinates specifically includes: measuring the coordinates of all common measurement points in the global coordinate system by using a laser tracker to obtain the set of common measurement points in the global coordinates q = [q 1 , q 2 , … q M , where M is the number of common measurement points, and q j = [x j y j z j T , j = 1, 2, … M.

[0014] Preferably, the step of arranging local measurement points in the measurement section, scanning the key features of each section by a laser scanner, obtaining the section feature point cloud and the coordinate information of the section common measurement points in the local coordinates of the laser scanner, and transforming the feature scan point cloud of the section into the point cloud in the global coordinate system specifically includes: transforming the storage tank feature scan point cloud P i of section i into the point cloud p i in the global coordinate system, and its three-dimensional conversion relationship is:

[0015] p i = R i P i + T i ,

[0016] ​Among them, R i is the rotation matrix represented by the rotation angle, specifically:

[0017]

[0018] T i is the translation matrix, expressed as:

[0019]

[0020] The solution of the parameters r = (α, β, γ, dx, dy, dz) of the rotation matrix and the translation matrix requires constructing an objective function, ε i :

[0021] ε i (r) = ||R i Q i +T i -q i ||,

[0022] where ||·|| is the norm of the vector.

[0023] Preferably, the particle swarm algorithm is used to solve the transformation parameter r that minimizes ε i and obtain p i .

[0024] Preferably, the step of integrating the partial segment scan point cloud in the global coordinate system to obtain the overall scan point cloud, obtaining the pose set of the key features of the storage tank under the action of gravity, and performing the simulation calculation of the gravity deformation of the storage tank to obtain the pose of the key features of the storage tank in the simulation coordinate system specifically includes: integrating the partial segment scan point cloud p i in the global coordinate system to obtain the overall scan point cloud p = [p 1 p 2 … p N , obtaining the pose set F = [F 1 F 2 …F K of the key features of the storage tank under the action of gravity, where K is the number of features, and F j = [x j y j z j T , j = 1, 2, …, K.

[0025] ​Preferably, the step of integrating the segment scanning point clouds in the global coordinate system to obtain the overall scanning point cloud, obtaining the position and posture set of the key features of the tank under the action of gravity, and performing a simulation calculation of the gravity deformation of the tank to obtain the position and posture of the key features of the tank in the simulation coordinate system specifically also includes: using the tank CAD model to perform a finite element simulation calculation of the gravity deformation of the tank in the current horizontal state to obtain a displacement set u=[u 1 u 2 … u K ], where u j =[ux j uy j u j ] T ; ux, uy, uz are the displacement components of the feature points in the simulation coordinate system respectively; through the ICP point cloud matching algorithm, the rotation matrix R and translation matrix T from the simulation coordinate system to the scanning global coordinate system are calculated, and the position f of the scanning feature point in the simulation coordinate system is calculated: f=RF+T.

[0026] Preferably, the step of compensating the characteristic posture obtained by horizontal scanning measurement according to the simulation deformation result to obtain the shape and position size of the super-long and long-thick common-bottom storage tank without the influence of gravity specifically comprises: compensating the characteristic posture obtained by horizontal scanning measurement based on the simulation deformation result to obtain the shape and position size of the super-long and long-thick common-bottom storage tank without the influence of gravity:

[0027] Compared with the prior art, the present invention integrates the global positioning of the laser tracker and the local feature precise scanning function of the laser scanner, making up for the limitations of using a single laser tracker or laser scanner to measure the overall shape and local fine features of the super-large structure, which can significantly reduce the splicing error introduced by multi-station scanning of the super-large structure and improve the measurement accuracy of the shape and position dimensions of the super-long, long, thick and common bottom tank. The shape and position dimensions of the super-long, long, thick and common bottom tank measured in the horizontal state are compensated in combination with the finite element simulation deformation results, thereby realizing the accurate measurement and evaluation of the shape and position dimensions of the super-long, long, thick and common bottom tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Figure 1 This is a flowchart of the method for accurately measuring and evaluating the shape and position dimensions of an ultra-long and thick common-bottom storage tank of the present invention;

[0030] Figure 2 Schematic diagram of the method for measuring the shape and position dimensions of an ultra-long and thick common-bottom storage tank based on the fusion of a laser tracker and a laser scanner in the present invention;

[0031] Figure 3 This is the flowchart for processing the scanned point cloud of the ultra-long and large-thickness common-bottom storage tank of the present invention;

[0032] Figure 4 This is the diagram of the simulation calculation results of the self-weight deformation of the ultra-long and large-thickness common-bottom storage tank of the present invention;

[0033] Figure 5 This is the schematic diagram of the method for evaluating the actual geometric dimensions of the ultra-long and large-thickness common-bottom storage tank of the present invention without the influence of gravity. Detailed implementation manners

[0034] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several changes and improvements can still be made. These all belong to the protection scope of the present invention.

[0035] Specifically, the present invention provides a method for accurately measuring and evaluating the geometric dimensions of an ultra-long and large-thickness common-bottom storage tank, as Figure 1 shown, the method includes the following steps:

[0036] S1: Segmentally scan the ultra-long and large-thickness common-bottom storage tank, and arrange a plurality of common measurement points in each scanned segment;

[0037] Specifically, as Figure 2 shown, taking the ultra-long and large-thickness common-bottom storage tank as the scanning object, segmentally scan the ultra-long and large-thickness common-bottom storage tank, divide the scanned segments according to the relative position relationship of the key features of the storage tank structure, and divide the features with relatively high scanning accuracy requirements for each other's relative poses into the same scanned segment, thereby obtaining N scanned segments of the storage tank. Set laser tracker common measurement points on the fixed fixture of the storage tank and number them 1-M. The common measurement points of the storage tank fixed fixture are fixedly arranged, and more than three common measurement points are arranged in each scanned segment.

[0038] S2: Measure the coordinates of all common measurement points in the global coordinate system by using a laser tracker to obtain the set of common measurement points in the global coordinates;

[0039] Specifically, measure the coordinates of all common measurement points in the global coordinate system by using a laser tracker to obtain the set of common measurement points in the global coordinates q = [q 1 , q 2 , … q M , where M is the number of common measurement points, and q j = [x j y j z j T ​, j = 1, 2, … M.

[0040] S3: Arrange local measurement points in the measurement section, scan the key features of each section through a laser scanner, obtain the section feature point cloud and the coordinate information of the section common measurement points in the local coordinates of the laser scanner, and transform the feature scan point cloud of the section into the point cloud in the global coordinate system;

[0041] Specifically, arrange local measurement points in the measurement section i (i = 1, 2, …, N). The measurement points are evenly arranged along the surface of the storage tank and are used for the local coordinate XOY of the laser scanner within the section i established, and can be removed and arranged on the next section after the scanning of a single section is completed.

[0042] Perform local point cloud scanning on the measurement section i to obtain the storage tank feature scan point cloud P in the local coordinate system of the section i , and the coordinate set of some common measurement points in the local coordinate system of the section i where n is the number of common measurement points in the section i, m j = 1, 2, …, M. Q i The corresponding global coordinate point set is:

[0043] Transform the storage tank feature scan point cloud P of the section i i into the point cloud p in the global coordinate system i , and its three-dimensional conversion relationship is:

[0044] p i = R i P i + T i

[0045] where R i is the rotation matrix represented by the rotation angle, specifically:

[0046]

[0047] T i is the translation matrix, expressed as:

[0048]

[0049] The parameters r = (α, β, γ, dx, dy, dz) of the rotation matrix and the translation matrix need to be solved by constructing an objective function, ε i :

[0050] ε i (r)= ||R i Q i + T i - qi ||,

[0051] where ||·|| is the norm of the vector.

[0052] Solve for the transformation parameter r that minimizes ε i using the Particle Swarm Optimization (PSO) algorithm and obtain p i .

[0053] S4: Integrate the segment scan point clouds in the global coordinate system to obtain the overall scan point cloud, obtain the pose set of the key features of the storage tank under the action of gravity, and perform a simulation calculation of the gravity deformation of the storage tank to obtain the pose of the key features of the storage tank in the simulation coordinate system;

[0054] Specifically, integrate the segment scan point clouds p i in the global coordinate system to obtain the overall scan point cloud p = [p 1 p 2 … p N , obtain the pose set F = [F 1 F 2 … F K of the key features of the storage tank under the action of gravity, as Figure 3 shown, where K is the number of features and F j = [x j y j z j T , j = 1, 2, …, K.

[0055] Conduct a finite element simulation calculation of the gravity deformation of the storage tank in the current horizontal state using the storage tank CAD model, as Figure 4 shown, to obtain the displacement set u = [u 1 u 2 … u K of the key features of the storage tank in the simulation coordinate system, where u j = [ux j uy j uz j T ; ux, uy, and uz are the displacement components of the feature points in the simulation coordinate system, respectively.

[0056] Calculate the rotation matrix R and translation matrix T from the simulation coordinate system to the scan global coordinate system using the ICP point cloud matching algorithm, and calculate the pose f of the scan feature points in the simulation coordinate system:

[0057] f = RF + T.

[0058] where f is the pose set of the feature points in the simulation coordinate system, expressed as: f = [f 1 f 2 … fK , where K is the number of features, and f j = [x j y j z j T , and j = 1, 2, …, K.

[0059] S5: Compensate the feature poses obtained by horizontal scanning measurement according to the simulation deformation results to obtain the geometric dimensions of the ultra-long and large-thickness common-bottom storage tank without the influence of gravity.

[0060] Specifically, compensating the feature poses obtained by horizontal scanning measurement based on the simulation deformation can further achieve an accurate evaluation of the geometric dimensions of the ultra-long and large-thickness common-bottom storage tank without the influence of gravity, as Figure 5 shown:

[0061]

[0062] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Without conflict, the embodiments of the present application and the features in the embodiments can be arbitrarily combined with each other.​

Claims

1. A method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank, characterized in that: The method comprises the following steps: Scan the super-long and thick common-bottom tank in sections, and arrange multiple common measuring points in each scanning section; A laser tracker is used to measure the coordinates of all common measuring points in the global coordinate system to obtain a set of common measuring points in the global coordinate system; Arrange local measuring points in the measuring section, scan the key features of each section with a laser scanner, obtain the section feature point cloud and the coordinate information of the section common measuring points in the local coordinates of the laser scanner, and transform the section feature scanning point cloud into a point cloud in the global coordinate system; The overall scanning point cloud is obtained by integrating the segment scanning point cloud in the global coordinate system, and the pose set of the key features of the tank under the action of gravity is obtained. The gravity deformation simulation calculation of the tank is then performed to obtain the pose of the key features of the tank in the simulation coordinate system. The characteristic posture obtained by horizontal scanning measurement is compensated according to the simulation deformation results to obtain the shape and position dimensions of the super-long and thick common-bottom tank without the influence of gravity.

2. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 1 is characterized in that: In the step of performing segmented scanning on the extra-long and thick common-bottom tank and arranging a plurality of common measuring points in each scanning segment, the scanning segments are divided according to the relative position relationship of key features of the tank structure, and features with high relative posture scanning accuracy requirements are divided into the same scanning segment to obtain N tank scanning segments, and a plurality of common measuring points are arranged in each scanning segment.

3. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 1 is characterized in that: The step of using a laser tracker to measure the coordinates of all public measuring points in the global coordinate system to obtain a set of public measuring points in the global coordinate system specifically includes: using a laser tracker to measure the coordinates of all public measuring points in the global coordinate system to obtain a set of public measuring points in the global coordinate system q = [q 1 ,q 2 ,L q M ], where M is the number of common measuring points, q j =[x j y j z j ] T , j=1,2,LM.

4. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 1 is characterized in that: The steps of arranging local measuring points in the measuring section, scanning the key features of each section by a laser scanner, obtaining the section feature point cloud and the coordinate information of the section common measuring points in the local coordinates of the laser scanner, and converting the section feature scanning point cloud into a point cloud in the global coordinate system specifically include: converting the tank feature scanning point cloud P of section i into a point cloud in the global coordinate system; i Transformed to the point cloud p in the global coordinate system i , its three-dimensional transformation relationship is: p i =R i P i +T i , Among them, R i is the rotation matrix expressed by the rotation angle, specifically: T i is the translation matrix, expressed as: The solution of the parameters of the rotation matrix and the translation matrix r = (α, β, γ, dx, dy, dz) requires constructing the objective function, ε i : ε i (r)=||R i Q i +T i -q i ||, Among them, ||·|| is the modulus of the vector.

5. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 4 is characterized in that: Solve the problem of ε by particle swarm algorithm i The smallest transformation parameter r, and get p i .

6. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 1 is characterized in that: The steps of integrating the segment scanning point cloud in the global coordinate system to obtain the overall scanning point cloud, obtaining the position and posture set of the key features of the tank under the action of gravity, and performing the gravity deformation simulation calculation of the tank to obtain the position and posture of the key features of the tank in the simulation coordinate system specifically include: i The integrated scanning point cloud p = [p1 p2 L p N ], and obtain the position and posture set F = [F1 F2 LF K ], where K is the number of features, F j =[x j y j z j ] T , j=1,2,L,K.

7. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 6 is characterized in that: The step of integrating the segment scanning point clouds in the global coordinate system to obtain the overall scanning point cloud, obtaining the position and posture set of the key features of the tank under the action of gravity, and performing the gravity deformation simulation calculation of the tank to obtain the position and posture of the key features of the tank in the simulation coordinate system specifically includes: using the tank CAD model to carry out the gravity deformation finite element simulation calculation of the tank in the current horizontal state to obtain the displacement set u=[u1 u2 L u K ], where u j =[ux j uy j u j ] T ; ux, uy, uz are the displacement components of the feature points in the simulation coordinate system respectively; through the ICP point cloud matching algorithm, the rotation matrix R and translation matrix T from the simulation coordinate system to the scanning global coordinate system are calculated, and the position f of the scanning feature point in the simulation coordinate system is calculated: f=RF+T.

8. The method for accurately measuring and evaluating the shape and position dimensions of an ultra-long, thick, common-bottom tank according to claim 1 is characterized in that: The step of compensating the characteristic posture obtained by horizontal scanning measurement according to the simulation deformation result to obtain the shape and position size of the super-long and thick common bottom storage tank without the influence of gravity specifically includes: compensating the characteristic posture obtained by horizontal scanning measurement based on the simulation deformation result to obtain the shape and position size of the super-long and thick common bottom storage tank without the influence of gravity:

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