CN114485438A - Method for measuring distance between round stand columns of large module steel structure - Google Patents
Method for measuring distance between round stand columns of large module steel structure Download PDFInfo
- Publication number
- CN114485438A CN114485438A CN202210014094.2A CN202210014094A CN114485438A CN 114485438 A CN114485438 A CN 114485438A CN 202210014094 A CN202210014094 A CN 202210014094A CN 114485438 A CN114485438 A CN 114485438A
- Authority
- CN
- China
- Prior art keywords
- columns
- column
- cloud data
- point cloud
- deck
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/14—Measuring arrangements characterised by the use of optical techniques for measuring distance or clearance between spaced objects or spaced apertures
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
The invention discloses a method for measuring the distance between round columns of a large-scale module steel structure, which comprises the steps of carrying out omnibearing scanning on columns by using a three-dimensional scanning technology, then carrying out processing such as splicing, denoising and point cloud data simplification to obtain complete point clouds of the columns, selecting deck plane point cloud data at the bottom positions of the columns, carrying out least square fitting to obtain a reference fitting plane and converting a coordinate system, intercepting the columns by using the reference fitting plane to obtain point cloud tangent plane circles, obtaining the circle center coordinates of the tangent plane circle at the bottom ends of the columns by calculation, and calculating the distance between the columns according to the circle center coordinates. The invention solves the problems of low detection efficiency and limited detection range and potential safety hazard existing in the traditional upright post distance measurement by a three-dimensional scanning technology, and has the advantages of large detection range, simple and convenient operation, high measurement speed, great improvement on upright post detection efficiency and detection range and the like.
Description
Technical Field
The invention relates to an engineering measurement technology, in particular to a method for measuring the distance between round stand columns of a large module steel structure.
Background
With the iterative update of the technology, the construction method of the large-scale marine module is improved day by day, in order to construct the marine module with high efficiency and high quality, the marine module needs to be disassembled into a single-layer sheet structure, and finally the marine module is integrally assembled.
The traditional method for measuring the distance between the existing stand columns mainly comprises two methods, the first method is manual drawing of a ruler, two measurers are needed to cooperate in operation, the distance between two measured stand column ports is measured by two persons through a ruler tool, and due to the fact that the module is large and the internal structure is complex, measurement accuracy is easily influenced. The second kind is that the total station gets the multiple spot on every cylinder, then carry out the fitting centre of a circle, solve the centre of a circle coordinate of port under the stand, solve the column spacing through every stand centre of a circle coordinate, use the total station to measure when measuring a large amount of stands in the module and need frequently change the station, too much shelter from the thing also can make the fitting out stand centre of a circle data receive the influence, and the total station gets the spot and just must need artifical supplementary point of pasting if guaranteeing the precision, this can increase the potential safety hazard equally, the mode efficiency of single-point measurement can receive very big influence when needing to carry out a large amount of measurement tasks simultaneously.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a method for measuring the distance between the round stand columns of the large-scale module steel structure.
The method comprises the steps of taking mass point cloud data on a circular stand column and a mounting plane at the bottom of the stand column by using a three-dimensional laser, generating cross sections through the point cloud data of the bottom of the stand column, intercepting the point cloud data of the bottom of the stand column, converting a three-dimensional space circle into a two-dimensional plane circle, performing circle center fitting by using a least square method, calculating coordinates of the circle center of the bottom of each stand column, and finally calculating the distance between the circle centers of the bottom of each stand column. The three-dimensional scanning technology has the advantages that manual assistance is not needed, a scaffold is not needed to be erected, potential safety hazards are hardly caused, the measuring speed is high, the measuring range is wide, and the upright post detection efficiency is greatly improved.
The technical scheme adopted by the invention is as follows: a method for measuring the distance between round columns of a large module steel structure comprises the following steps:
step 2, splicing part of the acquired deck upper surface point cloud data and part of the acquired upright post point cloud data of each station to obtain complete point cloud data of a module layer to be measured, wherein the complete point cloud data of the module layer to be measured comprises the complete deck upper surface point cloud data and the complete upright post point cloud data;
step 3, selecting complete point cloud data of the upper surface of the deck, and performing plane fitting on the upper surface of the deck by a least square method to obtain a reference fitting plane;
and 7, judging whether the distance between the stand columns meets the requirements or not, and adjusting the stand columns which do not meet the requirements.
Further, in step 1, before scanning the upper surface of the deck of the layer to be measured of the module and the columns on the deck by using the three-dimensional scanner, it is confirmed that each column of the layer to be measured is free from the shielding object, and the deck and each column are ensured to be in a static state.
Further, in step 1, for each upright, the upright is scanned through all positions around the upright so as to ensure that the point cloud data of each upright is complete.
Further, in step 7, the step of judging whether the distance between the columns meets the requirement is: and calculating an error value between the distance between the stand columns and the theoretical distance, judging whether the error value is within an allowable difference value, judging that the adjacent stand columns with the error value within the allowable difference value are qualified adjacent stand columns, and judging that the adjacent stand columns with the error value exceeding the allowable difference value are unqualified adjacent stand columns.
The invention has the beneficial effects that: under the condition that a plurality of persons are not needed for assisting and certain measuring personnel are avoided from working risks, the distance between the structural circular stand columns is measured through a three-dimensional scanning technology, and high-efficiency and high-precision detection is realized. The three-dimensional live-action model of the stand column is obtained through a three-dimensional scanning technology and a later point cloud data processing technology, accurate and visual stand column interval data are obtained after data extraction and analysis are carried out, post field construction personnel can adjust and install the stand column conveniently in the later period, and stand column detection efficiency and stand column installation efficiency are greatly improved.
Drawings
FIG. 1: the embodiment of the invention relates to a main structure diagram of a large marine module single-layer sheet;
FIG. 2: obtaining point cloud data maps of all stand columns according to the method;
FIG. 3: in the invention, a point cloud data schematic diagram of a vertical column tangent plane is intercepted by a translation reference fitting plane;
FIG. 4: tangent plane point cloud data of the bottom ends of the stand columns are obtained;
FIG. 5: the invention relates to tangent plane point cloud data and a fitting tangent plane circle of an upright post 1;
FIG. 6: the embodiment of the invention has the advantages that the measurement result of the distance between the upright columns is obtained;
FIG. 7: the method comprises the following steps of (1) obtaining an error range diagram of column spacing in the embodiment of the invention;
FIG. 8: the invention discloses a schematic diagram for detecting the distance between stand columns.
Detailed Description
In order to further understand the contents, features and effects of the present invention, the following embodiments are illustrated and described in detail with reference to the accompanying drawings:
the method is used for measuring the column spacing of each layer of the large marine multi-layer steel structure module, in the embodiment, one layer is taken as an example to explain the measuring method of the invention, and as shown in fig. 1, 26 columns are arranged in the layer.
The invention solves the problems of low detection efficiency and limited detection range and potential safety hazard in the traditional upright post distance measurement through a three-dimensional scanning technology, provides a method which has a larger detection range, is simple and convenient to operate and has high measurement speed, and greatly improves the upright post detection efficiency and the detection range. The specific measurement method is as follows:
And 2, importing the scanned point cloud data into FARO SCENE software through a PC for splicing, checking a splicing report of the FARO SCENE software, adjusting splicing parameters according to the report, and ensuring that the splicing precision after splicing is within +/-3 mm. And after point cloud data meeting the splicing error are obtained, cutting and deleting redundant point clouds in the point cloud data except for the upright post and the deck through the editing function of FARO SCENE software to obtain complete point cloud data of a layer to be measured of the module (including complete point cloud data of the upper surface of the deck of the layer and complete point cloud data of the upright post). FIG. 2 is a processed stud point cloud.
Step 3, selecting complete point cloud data of the cut deck, wherein the elevation of the deck point cloud data is not fixed, an optimal plane (namely a reference fitting plane) needs to be calculated through an optimal plane equation, the calculated optimal plane is used as an XY plane of a coordinate system, and meanwhile, the cross section of the upright column is also intercepted, and the optimal plane equation is as follows:
z＝ax+by+c
in the formula, (x, y, z) is coordinates under a Cartesian coordinate system, a, b and c are three generation parameters, and the calculation is carried out by using a least square method:
in the formula (x)i，yi，zi) Is the bottom position of the upright postThe ith point cloud data coordinate in the deck point cloud data is located, wherein i is 1,2, …, n, n is the total number of the deck point cloud data at the bottom position of the upright column,
for the sum of the squares of the deviation values of the distance least squares of all the measurement points, according to the principle of least squares
At a minimum, a, b, c are separately derived and then set to zero:
three parameters a, b, c of the best plane are then calculated:
the distance from the coordinate origin (the orientation point with the origin selected on the deck) to the optimal plane is calculated as:
from which the best plane (i.e., the reference fit plane) can be obtained.
And 4, aligning the XY plane of the coordinate system with the reference fitting plane, assuming that the elevation of the reference fitting plane is 0mm, namely, the Z values of the points on the reference fitting plane are both 0, moving the reference fitting plane to the position of the lower port of the upright column along the height direction of the upright column to obtain the fitting plane of the lower port of the upright column as shown in FIG. 3, and acquiring point cloud data of each upright column on the fitting plane of the lower port of the upright column, wherein the point cloud data is called tangent plane point cloud data as shown in FIG. 4. In this embodiment, the elevation +200mm is selected as the position of the lower port of the column, that is, the position 200mm higher than the reference fitting plane is the position of the lower port of the column, and the Z values of the points on the fitting plane of the lower port of the column with the elevation +200mm are all 200.
And 5, fitting the tangent plane point cloud data of each upright column by a least square method to obtain tangent plane circles of each upright column on the fitting plane of the lower port of the upright column, as shown in FIG. 5, and extracting the center coordinates of each tangent plane circle. The equation for calculating the optimal center coordinate is as follows:
x2+y2+dx+ey+f＝0
in the formula, d, e and f are parameters to be solved.
Wherein δ is the sum of the square of the circumferential point and the optimum circumferential deviation value, (x'j，y′j) And j is the j point cloud data coordinate in the point cloud tangent plane data of the calculated tangent plane circle, wherein j is 1, 2.
According to the least squares principle, to minimize δ, δ is differentiated on d, e, f, respectively:
from this, the parameters d, e, f of the circle can be calculated:
finally, the circle center is obtained as follows:
(x+0.5d)2+(y+0.5)2＝1/4d2+1/4e2-f
x′0＝-1/2d，y′0＝-1/2e
in formula (II), x'0Is the best circle center coordinate x value, y'0The value of the optimal circle center coordinate y is obtained.
And adding the Z value coordinate obtained by calculation in the step 4, namely the three-dimensional coordinate of the optimal circle center, as shown in the following table:
TABLE 1 circular center coordinates of the bottom of the cylinder (unit: mm)
And 6, selecting two vertical column circle centers which are farthest in the east-west direction and the south-north direction to be connected with the center of the vertical column based on the centers of the four vertexes of the vertical columns according to the fitted tangent plane circle centers, wherein the two connected straight lines are the X axis and the Y axis, orienting the integral point cloud data according to the actual direction of a field module to ensure that the arrangement direction of the vertical columns is consistent with the arrangement direction of the field vertical columns, introducing X, Y coordinates of the fitted vertical column tangent plane circle centers into a CAD, and measuring the circle center distance of the tangent plane circle at the bottom end of each vertical column on the CAD, wherein all numerical values in the graph 6 are in millimeter (mm) as shown in the graph 6. The distance between the centers of the tangent plane circles is the distance between the stand columns.
Step 7, formulating a column spacing error range diagram according to the requirements of the project specification, as shown in fig. 7, wherein the upper number 40000 in fig. 7 represents the theoretical spacing between the columns 1 and 4, between the columns 5 and 6, between the columns 7 and 8, between the columns 9 and 12, between the columns 13 and 14, between the columns 15 and 18, between the columns 19 and 22, and between the columns 23 and 26;
the number "14000" indicates the theoretical spacing of columns 1 and 2, 3 and 4, 9 and 10, 11 and 12, 15 and 16, 17 and 18, 19 and 20, 21 and 22, 23 and 24, and 25 and 26;
the number "12000" indicates the theoretical spacing between columns 2 and 3, columns 10 and 11, columns 16 and 17, columns 20 and 21, and columns 24 and 25;
the number "58000" on the right in fig. 7 indicates the theoretical spacing of the uprights 1 and 26, 2 and 25, 3 and 24, 4 and 23;
the number "10000" represents the theoretical spacing between the columns 15 and 22, 16 and 21, 17 and 20, 18 and 19;
the number "8000" indicates the theoretical spacing of columns 1 and 6, 6 and 7, 7 and 12, 12 and 13, 13 and 18, 19 and 26, 20 and 25, 21 and 24, 22 and 23, 14 and 15, 9 and 14, 8 and 9, 5 and 8, 4 and 5.
For the numbers with "+" sign in fig. 7, "+ 22" indicates, in the lateral direction, that the allowable difference between the actual and theoretical pitches of the columns 5 and 6, 7 and 8, and 13 and 14 is 22 mm;
"+ 8" indicates that the allowable difference between the actual and theoretical spacings of column 1 and column 2, column 3 and column 4, column 9 and column 10, column 11 and column 12, column 15 and column 16, column 17 and column 18, column 19 and column 20, column 21 and column 22, column 23 and column 24, and column 25 and column 26 is 8 mm;
"+ 6" indicates that the allowable difference between the actual and theoretical spacings of the uprights 2 and 3, 10 and 11, 16 and 17, 20 and 21, 24 and 25 is 6 mm.
In the vertical direction, "+ 12" indicates that the allowable difference between the actual spacing and the theoretical spacing of the upright 2 and the upright 11, and between the upright 3 and the upright 10 is 12 mm;
"+ 8" indicates that the allowable difference between the actual and theoretical spacings of the columns 11 and 17, 10 and 16 is 8 mm;
"+ 5" indicates that the allowable difference between the actual and theoretical spacings of the uprights 15 and 22, 16 and 21, 17 and 20, 18 and 19 is 5 mm;
"+ 4" indicates that the allowable difference between the actual and theoretical spacings of column 1 and column 6, column 6 and column 7, column 7 and column 12, column 12 and column 13, column 13 and column 18, column 19 and column 26, column 20 and column 25, column 21 and column 24, column 22 and column 23, column 14 and column 15, column 9 and column 14, column 8 and column 9, column 5 and column 8, and column 4 and column 5 is 4 mm.
All values in fig. 7 are in millimeters (mm).
And outputting a measurement report of the distance between the bottom ends of the columns by referring to the column distance error range diagram to provide field reference, judging whether the measured error value between the column distance and the corresponding theoretical distance is within an allowable difference value or not according to the column distance error range diagram, and outputting an adjustment scheme to a field constructor to adjust the adjacent columns of which the error values exceed the allowable difference value.
Fig. 8 is a schematic diagram of pillar spacing detection, wherein three circles are tangent plane circles at the bottom ends of pillars 3, 4 and 5, and the three circles are all formed by fitting point cloud data at the bottom ends of pillars corresponding to the elevations, in the diagram, the value of 7999 is the actual spacing between the bottom ends of pillars 4 and 5, and the value of 14001 is the actual spacing between the bottom ends of pillars 3 and 4.
The three-dimensional scanning technology has the advantages that manual assistance is not needed, potential safety hazards are avoided, the precision is not influenced by frequent station transfer superposition errors, and the efficiency and the high precision are realized through the measurement of the scanner, so that the detection efficiency of the distance between the stand columns is greatly improved.
Although the preferred embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are only illustrative and not restrictive, and those skilled in the art can make many modifications without departing from the spirit and scope of the invention as claimed.
Claims (5)
1. A method for measuring the distance between round stand columns of a large module steel structure is characterized by comprising the following steps:
step 1, scanning the upper surface of a deck of a layer to be measured of a module and an upright column to be measured on the deck by using a three-dimensional scanner in a substation scanning mode until the whole scanning of the upper surface of the deck and the upright column is completed, wherein each station scans to obtain partial cloud data of upper surface points of the deck and partial cloud data of the upright column;
step 2, splicing part of the acquired deck upper surface point cloud data and part of the acquired upright post point cloud data of each station to obtain complete point cloud data of a module layer to be measured, wherein the complete point cloud data of the module layer to be measured comprises the complete deck upper surface point cloud data and the complete upright post point cloud data;
step 3, selecting complete point cloud data of the upper surface of the deck, and performing plane fitting on the upper surface of the deck by a least square method to obtain a reference fitting plane;
step 4, moving the reference fitting plane to the position of the lower port of the upright column along the height direction of the upright column to obtain a fitting plane of the lower port of the upright column, and acquiring point cloud data of each upright column on the fitting plane of the lower port of the upright column, wherein the point cloud data is called tangent plane point cloud data;
step 5, fitting the tangent plane point cloud data of each upright column by a least square method to obtain tangent plane circles of each upright column on a fitting plane of a lower port of the upright column, and extracting the center coordinates of each tangent plane circle;
step 6, calculating the distance between the centers of the tangent plane circles so as to obtain the distance between the stand columns;
and 7, judging whether the distance between the stand columns meets the requirements or not, and adjusting the stand columns which do not meet the requirements.
2. The method for measuring the distance between the round columns of the large module steel structure according to claim 1, wherein in step 1, before the three-dimensional scanner is used for scanning the upper surface of the deck of the layer to be measured of the module and the columns on the deck, it is confirmed that each column of the layer to be measured is not provided with a shelter, and the deck and each column are ensured to be in a static state.
3. The method for measuring the distance between the round columns of the large module steel structure according to claim 1, wherein in step 1, in the process of scanning the upper surface of the deck of the layer to be measured of the module and the columns to be measured on the deck by using a three-dimensional scanner through substation scanning, the continuity of each scanning station is ensured, and the scanning stations have a common surface.
4. The method for measuring the distance between the round columns of the large-scale module steel structure according to claim 1, wherein in the step 1, for each column, the column is scanned through all positions around the column to ensure the integrity of point cloud data of each column.
5. The method for measuring the distance between the round columns of the large module steel structure according to claim 1, wherein in the step 7, the step of judging whether the distance between the columns meets the requirement is as follows: and calculating an error value between the distance between the stand columns and the theoretical distance, judging whether the error value is within an allowable difference value, judging that the adjacent stand columns with the error value within the allowable difference value are qualified adjacent stand columns, and judging that the adjacent stand columns with the error value exceeding the allowable difference value are unqualified adjacent stand columns.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210014094.2A CN114485438A (en) | 2022-01-06 | 2022-01-06 | Method for measuring distance between round stand columns of large module steel structure |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210014094.2A CN114485438A (en) | 2022-01-06 | 2022-01-06 | Method for measuring distance between round stand columns of large module steel structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN114485438A true CN114485438A (en) | 2022-05-13 |
Family
ID=81510523
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210014094.2A Pending CN114485438A (en) | 2022-01-06 | 2022-01-06 | Method for measuring distance between round stand columns of large module steel structure |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114485438A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024021262A1 (en) * | 2022-07-25 | 2024-02-01 | 中建钢构工程有限公司 | Design drawing processing method and system, and electronic device and storage medium |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017022901A1 (en) * | 2015-08-05 | 2017-02-09 | 삼인정보시스템(주) | Size measuring apparatus and method based on three-dimensional point cloud data |
| CN110095060A (en) * | 2019-03-12 | 2019-08-06 | 中建三局第一建设工程有限责任公司 | Steel construction rapid quality detection method based on 3-D scanning technology |
| CN111127312A (en) * | 2019-12-25 | 2020-05-08 | 武汉理工大学 | Method for extracting circle from point cloud of complex object and scanning device |
| CN111238386A (en) * | 2019-11-26 | 2020-06-05 | 中国航空工业集团公司北京长城计量测试技术研究所 | Method for measuring minimum spacing of engine pipelines |
| CN111811463A (en) * | 2020-06-02 | 2020-10-23 | 中国海洋石油集团有限公司 | Method for accurately measuring span of stand column at bottom of block |
| CN112414305A (en) * | 2020-11-26 | 2021-02-26 | 江南造船(集团)有限责任公司 | Container ship guide rail frame measuring method and system |
| CN113865570A (en) * | 2021-10-15 | 2021-12-31 | 博迈科海洋工程股份有限公司 | Steel structure circular stand column verticality measuring method |
-
2022
- 2022-01-06 CN CN202210014094.2A patent/CN114485438A/en active Pending
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017022901A1 (en) * | 2015-08-05 | 2017-02-09 | 삼인정보시스템(주) | Size measuring apparatus and method based on three-dimensional point cloud data |
| CN110095060A (en) * | 2019-03-12 | 2019-08-06 | 中建三局第一建设工程有限责任公司 | Steel construction rapid quality detection method based on 3-D scanning technology |
| CN111238386A (en) * | 2019-11-26 | 2020-06-05 | 中国航空工业集团公司北京长城计量测试技术研究所 | Method for measuring minimum spacing of engine pipelines |
| CN111127312A (en) * | 2019-12-25 | 2020-05-08 | 武汉理工大学 | Method for extracting circle from point cloud of complex object and scanning device |
| CN111811463A (en) * | 2020-06-02 | 2020-10-23 | 中国海洋石油集团有限公司 | Method for accurately measuring span of stand column at bottom of block |
| CN112414305A (en) * | 2020-11-26 | 2021-02-26 | 江南造船(集团)有限责任公司 | Container ship guide rail frame measuring method and system |
| CN113865570A (en) * | 2021-10-15 | 2021-12-31 | 博迈科海洋工程股份有限公司 | Steel structure circular stand column verticality measuring method |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024021262A1 (en) * | 2022-07-25 | 2024-02-01 | 中建钢构工程有限公司 | Design drawing processing method and system, and electronic device and storage medium |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107167790B (en) | A kind of two step scaling method of laser radar based on Calibration Field | |
| CN107402001B (en) | Ultrahigh-rise building construction deviation digital inspection system and method based on 3D scanning | |
| CN103292748B (en) | A kind of split of many substrates based on laser measurement detection method | |
| CN106886659A (en) | The virtual pre-splicing and detection method of steel structure bridge based on 3 D laser scanning and cloud platform | |
| CN102052897B (en) | Method for positioning center and four median lines of cylinder | |
| CN103808277B (en) | A kind of modification method of multisensor point cloud error | |
| CN111174721A (en) | Hoisting mechanical structure deformation detection method based on three-dimensional laser scanning | |
| CN112884647A (en) | Embedded part construction positioning method based on BIM point cloud technology guidance | |
| CN103389136A (en) | External floating top vertical metal can volume measuring method based on three-dimensional laser scanning technology | |
| CN109405817B (en) | Method for detecting verticality of circular stand column | |
| CN103322916A (en) | Large-scale vertical tank volume measurement system and method based on three-dimensional laser scanning method | |
| CN113865570B (en) | Method for measuring verticality of steel structure round upright post | |
| CN103026310B (en) | Method for realizing the spatial transformation from machining points to reference points of installation survey | |
| CN207907883U (en) | A kind of airplane horizontal survey system of high-efficiency high-accuracy | |
| CN114541480B (en) | Steel shell immersed tube assembly precision inspection method and system | |
| CN103673976A (en) | Method and system for converting and unifying composite type precision measuring coordinate system | |
| CN114332402B (en) | Steel bridge simulation pre-assembly method integrating ground type and hand-held laser scanning | |
| CN112017293A (en) | Method for measuring geometric initial defects of round steel pipe | |
| CN114485438A (en) | Method for measuring distance between round stand columns of large module steel structure | |
| CN114875971A (en) | Measuring device suitable for large prefabricated part of fully-assembled subway station and refined installation control method | |
| CN106643582A (en) | Large mesh antenna reflector profile high-precision test method | |
| CN110095112A (en) | A kind of pre-manufactured steel member position inspection method based on spatial digitizer technology | |
| CN112878736A (en) | Positioning device, positioning unit, positioning assembly and unloading method of positioning assembly | |
| CN117368203A (en) | Complex shape surface defect identification positioning and shape detection method based on point cloud matching | |
| CN107462186A (en) | 4th axle arrangement for measuring verticality and the 4th shaft flange end face squareness detection method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |