3D shape measurement system

Abstract

This disclosure aims to make it possible to correct the displacement of the central axis of a tubular body caused by deformation of the tubular body. [Solution] This disclosure provides an analysis device that acquires measurement data of the surface shape of a target to be measured, calculates the longitudinal central axis of a tubular body in the target to be measured using the measurement data, and corrects the deviation of the central axis of the tubular body using information other than the tubular body obtained from the measurement data.

Description

Technical Field

[0001] This disclosure relates to a technique for arithmetic processing of measurement data measured by three-dimensional shape measurement.

Background Art

[0002] Techniques have been proposed for grasping the wall thickness of a member forming a surface shape using three-dimensional shape measurement such as a laser scanner (see, for example, Patent Document 1). In Patent Document 1, the wall thickness of a member forming a surface shape is measured by fitting the surface shape and the cross-sectional shape.

[0003] In Patent Document 1, for a water-cooled pipe used in a boiler, in order to cope with bending due to high heat, the central coordinates for each cross-section orthogonal to the longitudinal direction of the tubular body are obtained, and the sequence of these central coordinates is used as the central axis. Then, using this central axis, the surface shape and the cross-sectional shape are fitted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, when the tubular body is deformed, there is a problem that the wall thickness of the tubular body cannot be correctly measured, that is, the deformation of the tubular body cannot be correctly measured. The purpose of this disclosure is to enable accurate measurement of the deformation of the tubular body.

Means for Solving the Problems

[0006] The inventors discovered that when a tubular body is deformed, its central axis is pushed down in the direction of deformation, and this displacement of the central axis causes a misalignment in the fitting. Therefore, this disclosure provides a method for correcting the displacement of the central axis of a tubular body when it is deformed.

[0007] The three-dimensional shape measurement system of this disclosure comprises a measuring device (91) for measuring the surface shape of an object to be measured, and an analysis device (92) for acquiring measurement data obtained by the measuring device.

[0008] The analysis device acquires measurement data of the surface shape of the object to be measured, Using the aforementioned measurement data, the longitudinal central axis of the tubular body in the measurement target is calculated. The deviation of the central axis is corrected using information other than the tubular body obtained from the measurement data.

[0009] Other information than the tubular body is, for example, information about the fixing parts (12, 13) provided on the side surface of the tubular body.

[0010] The analysis device may calculate the boundary point between the tubular body and the fixed part, and correct the deviation of the central axis of the tubular body based on the relative position between the boundary point and the central axis of the tubular body. The boundary point may be a point where the curvature of the tubular body changes discontinuously.

[0011] The analysis device may use the corrected central axis to calculate the reference shape of the inner surface of the tubular body, and use the surface shape of the tubular body obtained from the measurement data and the reference shape to calculate the wall thickness of the tubular body.

[0012] The analysis device may use the corrected central axis to calculate the reference shape of the outer surface of the tubular body, and use the surface shape of the tubular body obtained from the measurement data and the reference shape to calculate the amount of deformation of the tubular body.

[0013] Furthermore, the above disclosures can be combined as much as possible. [Effects of the Invention]

[0014] According to this disclosure, it is possible to correct for the displacement of the central axis of a tubular body due to deformation. Therefore, the wall thickness and deformation of the tubular body can be accurately measured. [Brief explanation of the drawing]

[0015] [Figure 1] An example of the 3D shape measurement system described herein is shown. [Figure 2] An example of surface shape measured by a measuring device is shown. [Figure 3] An example of a measurement target is shown below. [Figure 4] An example of a central axis misalignment is shown. [Figure 5] An example of a central axis misalignment is shown. [Figure 6] An example of a central axis misalignment is shown. [Figure 7] An example of the measurement method disclosed herein is shown. [Figure 8] This is an explanatory diagram illustrating an example of calculating the central axis in procedure S13. [Figure 9] This is an explanatory diagram illustrating an example of calculating the central axis in procedure S13. [Figure 10] An example of the calculation result of the deformation amount of the tubular body 11 in procedure S16 is shown. [Figure 11] This is an explanatory diagram illustrating an example of calculating the central axis in procedure S13. [Figure 12] This is an explanatory diagram illustrating an example of calculating the central axis in procedure S13. [Figure 13] An example of the calculation result of the deformation amount of the tubular body 11 in procedure S16 is shown. [Modes for carrying out the invention]

[0016] Embodiments of this disclosure will be described in detail below with reference to the drawings. However, this disclosure is not limited to the embodiments shown below. These examples are illustrative, and this disclosure can be implemented in various modified and improved forms based on the knowledge of those skilled in the art. In this specification and in the drawings, components with the same reference numerals refer to the same components.

[0017] Figure 1 shows an example of the three-dimensional shape measurement system of this disclosure. The three-dimensional shape measurement system of this embodiment comprises a measuring device 91 and an analysis device 92. The measuring device 91 measures the surface shape of the object to be measured. The analysis device 92 acquires the measurement data obtained by the measuring device 91 and performs arbitrary calculation processing. The object to be measured in this embodiment includes a plurality of tubular bodies 11-1, 11-2, and 11-3. Hereinafter, when tubular bodies 11-1, 11-2, and 11-3 are not distinguished, they will be referred to as tubular body 11.

[0018] The measuring device 91 is a device capable of measuring the three-dimensional shape of the surface of an object to be measured. An example of the measuring device 91 is a laser scanner that measures the surface shape of an object by irradiating it with measuring light and measuring the reflected light. The analysis device 92 is a computer that performs arbitrary processing using the measurement results from the measuring device 91.

[0019] The sides of the tubular bodies 11-1, 11-2, and 11-3 are provided with components other than the tubular bodies, such as membranes 12-1, 12-2, and fixing parts 13-1 and 13-3. Membranes 12-1 and 12-2 function as fixing parts for connecting the tubular bodies 11-1, 11-2, and 11-3 to each other. Fixing parts 13-1 and 13-3 function as fixing parts for fixing the tubular body 11 to components other than the tubular body 11. The fixing part of this disclosure includes both membranes 12-1, 12-2 and fixing parts 13-1 and 13-3. Hereinafter, when membranes 12-1 and 12-2 are not distinguished, they will be referred to as membrane 12.

[0020] Figure 2 shows an example of the surface shape of a tubular body measured by the measuring device 91. When the tubular body 11 can only be measured from one side, and the tubular body 11 is connected by a membrane 12, the surface shape of the tubular body 11 will not be tubular. Furthermore, as shown in Figure 3, the shape of the tubular body 11 may deform over time due to wear, dents, buildup, and replacement. Therefore, when calculating the central axis based on the curvature of the surface shape of the tubular body 11 measured by the measuring device 91, there is a problem in that the central axis of the tubular body 11 is misaligned.

[0021] Figure 4 shows an example of a central axis displacement. When the surface of the tubular body 11 wears down, it takes on the surface shape 11A shown in Figure 4(a). Therefore, the measuring device 91 measures the surface shape 11A shown in Figure 4(b). At this time, when the analysis device 92 calculates the central axis based on the curvature of the surface shape 11A, the circle C2 calculated based on the curvature of the surface shape 11A becomes larger than the tubular body 11. Therefore, the central axis A2 calculated using circle C2 will have a value on the z axis that is different from the original central axis A1 of the tubular body 11. In the first place, the z-axis coordinate of the surface shape 11A is lower than that of the tubular body 11. As a result, when the surface of the tubular body 11 wears down, the central axis A1 of the tubular body 11 sinks significantly in the z-axis direction to the central axis A2.

[0022] Figure 5 shows an example of a central axis misalignment. If the tubular body 11 has a recess 11B as shown in Figure 5(a), the analysis device 92 calculates the central axis based on the curvature of the surface shape 11C other than the recess 11B, as shown in Figure 5(b). Since the surface shape 11C is less than half the size of the tubular body 11, the error in the circle C3 calculated based on the curvature of the surface shape 11C tends to be large, as shown in Figure 5(c). Figure 5(c) is an example where the error occurs in the direction that the diameter of the circle is calculated to be larger than it is actually, but conversely, the diameter of the circle may also be calculated to be smaller than it is actually. In addition, the surface shape 11C may be distorted by the recess 11B. As a result of these factors, if the tubular body 11 has a recess 11B, the central axis A1 of the tubular body 11 will be misaligned with the central axis A3 in the z-axis and x-axis directions.

[0023] To prevent the shift in the central axis due to the change in the radius of curvature of the tubular body 11, it is conceivable to correct the diameters of circles C2 and C3 to the diameter of the tubular body 11. However, because the curvature of the surface shape 11A is large, there is a problem in that the result differs depending on where on the surface shape 11A the diameter of the tubular body 11 is aligned, as shown in A4 in Figure 6(a), A5 in Figure 6(b), and A6 in Figure 6(c). Furthermore, the coordinates on the z axis of the surface shape 11A are shifted from the coordinates on the z axis of the original tubular body 11. For these reasons, it is not possible to derive the correct central axis A1 simply by using the diameter of the tubular body 11.

[0024] (First Embodiment) Figure 7 shows an example of the measurement method of the present disclosure. In this embodiment, the three-dimensional shape measurement system of the present disclosure has steps S11 to S16. In step S11, the measuring device 91 measures the object to be measured. In step S12, the analysis device 92 acquires the measurement data obtained in step S11 from the measuring device 91. In step S13, the analysis device 92 uses the measurement data to calculate the longitudinal central axis of the tubular body 11 in the object being measured. In step S14, the analysis device 92 corrects the deviation of the central axis of the tubular body 11 using information other than the tubular body 11 obtained from the measurement data. In step S15, the analysis device 92 calculates the reference shape of the tubular body 11 using the central axis corrected in step S14. In step S16, the analysis device 92 calculates the difference between the surface shape obtained in step S11 and the reference shape obtained in step S15.

[0025] (Procedures S11 and S12) In this embodiment, in step S11, the surface shapes of the tubular body 11, the membrane 12, and the fixing part 13 are measured. In step S12, the analysis device 92 acquires measurement data of the surface shapes of the tubular body 11, the membrane 12, and the fixing part 13.

[0026] Regarding the measurement procedure S11 of the surface shape of the tubular body 11, any method capable of measuring the surface shape of the tubular body 11 as shown in FIG. 2, including the measuring device 91, can be adopted. Procedure S12 may be performed after procedure S11, or procedure S12 may be performed simultaneously with procedure S11.

[0027] (Procedure S13) The analysis device 92 calculates the central axis of each position in the longitudinal direction of the tubular body 11. The method of calculating the central axis can be, for example, calculating the central axis of the cross-sectional shape in the longitudinal direction of the tubular body 11 using at least either the curvature or the outer diameter of the tubular body 11, and connecting this in the longitudinal direction of the tubular body 11 to calculate it.

[0028] (Procedure S14) Regarding information other than the tubular body 11 obtained from the measurement data, information on regions with less deformation such as wear and dents compared to the tubular body 11 among the surface shapes included in the measurement data can be used. For example, the membrane 12 can be exemplified. As shown in FIG. 8, the membrane 12 has a value of the z-axis of z A in the plane P A Therefore, the analysis device 92 corrects the deviation of the central axis of the tubular body 11 based on the relative position between the plane P A of the membrane 12 and the central axis C A of the tubular body 11.

[0029] For example, when the membrane 12 is arranged on a plane passing through the central axis of the tubular body 11, the analysis device 92 shifts T 12 half of the thickness T 12 / 2 in the z-axis direction from the plane P A at z = z A Thereby, the analysis device 92 can calculate the value z C of the z-axis of the central axis. If the fixing part 13-3 is also arranged on the plane P A , the plane P A may be calculated including the information of the fixing part 13-3 in addition to the membrane 12.

[0030] In FIG. 8, the plane having the value z C of the z-axis of the central axis is PC This is shown. The analysis device 92 calculates the z-axis value of the central axis of the tubular body 11 obtained in procedure S13 as the value z C Correction is performed using the value z. At this time, the z-axis value of the central axis of the tubular body 11 obtained in step S13 is set to the value z C This can be replaced with this. This allows the central axis of the tubular body 11 to be corrected.

[0031] The method for calculating the z-axis value of the central axis is not limited to this. For example, as shown in Figure 9, coordinate P E (x E ,z A Alternatively, a point A7 at a predetermined angle θ and distance from ) may be found, and the z-axis value z7 of point A7 may be used as the z-axis value of the central axis. Coordinate P E (x E ,z A The angle θ from that point can be determined using a portion of the tubular body 11 that is not deformed by wear, dents, buildup, replacement, etc.

[0032] Here, coordinate P E (x E ,z E ) is the coordinate of the boundary point between the tubular body 11 and the membrane 12. At the boundary point between the tubular body 11 and the membrane 12, the curvature changes discontinuously. Therefore, the analysis device 92 uses coordinate P to determine the position where the curvature changes discontinuously in a part of the circle. E (x E ,z E It can be used for this purpose. Locations where the curvature changes discontinuously can be detected, for example, by checking whether the difference in curvature between adjacent regions exceeds a certain threshold.

[0033] (Procedure S15) The analysis device 92 calculates the reference shape of the tubular body 11 using the corrected central axis obtained in procedure S14. Examples of reference shapes include the outer surface of the tubular body 11 that is free from deformation such as wear, dents, buildup, or replacement, and the inner surface of the tubular body 11. These reference shapes can be calculated by obtaining the outer or inner diameter of the tubular body 11, provided that the central axis is known.

[0034] (Procedure S16) The analysis device 92 calculates the difference between the reference shape obtained in step S15 and the surface shape of the tubular body 11 obtained in step S12. At this time, the corrected central axis obtained in step S14 is used to superimpose the reference shape obtained in step S15 and the surface shape of the tubular body 11 obtained in step S12.

[0035] For example, if the reference shape is the outer surface of the tubular body 11, the amount of deformation of the tubular body 11 can be calculated using the surface shape of the tubular body 11 obtained from the measurement data and the reference shape. If the reference shape is the inner surface of the tubular body 11, the wall thickness of the tubular body 11 can be calculated using the surface shape of the tubular body 11 obtained from the measurement data and the reference shape.

[0036] Figure 10 shows an example of the measurement results of the deformation amount of the tubular body 11. Figure 10(a) shows the case when the correct central axis A1 is used, Figure 10(b) shows the case when no central axis correction is performed, and Figure 10(c) shows the case when the central axis in the z-axis direction is corrected. According to the accurate measurement shown in Figure 10(a), the surface of the tubular body 11 is deformed. Without central axis correction, as shown in Figure 10(b), it is measured as deformation of the back surface of the tubular body 11. In contrast, in this embodiment shown in Figure 10(c), similar to Figure 10(a), it is detected as deformation of the surface of the tubular body 11, rather than deformation of the back surface of the tubular body 11.

[0037] As described above, the 3D shape measurement system of this embodiment corrects the misalignment of the central axis of the tubular body 11 in the z-axis direction during steps S13 and S14. Therefore, this embodiment makes it possible to accurately measure the deformation of the tubular body 11.

[0038] (Second embodiment) As seen in the example in Figure 10(c), the measurement results show deformation in the x-axis direction on the back surface of the tubular body 11. This is thought to be due to the effects of deformation as explained in Figure 5. Therefore, in this embodiment, in procedure S14, the analysis device 92 corrects the displacement of the central axis of the tubular body 11 in the x-axis direction.

[0039] For example, as shown in Figure 11, the analysis device 92 determines the coordinates P of two boundary points where the curvature of the tubular body 11 changes discontinuously in the longitudinal cross-section. D (x D ,z D ) and P E (x E ,z E ) is determined, and these coordinates are used to calculate the x-coordinate of the central axis of the tubular body 11. For example, z D ≒z E Therefore, x D and x E Midpoint P F (x F ,z F Calculate ).

[0040] Regarding the fixing part 13-1, the plane P A and are arranged in the z-axis direction perpendicular to the central axis of the tubular body 11. In this configuration, as shown in Figure 12, there are two boundary points P where the curvature changes discontinuously at the fixed part 13-1. G (x G ,z G ) and P H (x H ,z H ) can be determined, and these coordinates can be used to calculate the x-coordinate of the central axis of the tubular body 11. For example, z G ≒z H Therefore, x G and x H Midpoint P I (x I ,z I ) calculate the coordinate x I Let this be the x-axis of the central axis A1.

[0041] Furthermore, as shown in Figure 12, the straight line L represents the thickness of the fixed part 13-1. G1 and L G2 Using this, the center line L of the thickness of the fixed part 13-1 G3 Find the center line L G3 The x-coordinate of may be defined as the x-axis of the central axis A1.

[0042] In step S14, the analysis device 92 determines the value of the z axis of the central axis A1, zC When we can find the coordinate (x F ,z C ) can be determined. In this case, the analysis device 92 uses the central axis obtained in step S13 to determine the coordinate (x F ,z C The correction is made based on the coordinate (x). At this time, the analysis device 92 uses the central axis obtained in step S13 as coordinate (x F ,z C ) can be replaced with this.

[0043] Procedures S15 and S16 are the same as in the first embodiment.

[0044] Figure 13 shows an example of the measurement results for the deformation of the tubular body 11. Figure 13(a) shows the case when the correct central axis A1 is used, Figure 13(b) shows the case when no correction is made to the central axis, and Figure 13(c) shows the case when the central axis is corrected in the x-axis and z-axis directions. Figures 13(a) and 13(b) are the same as Figures 10(a) and 10(b). In the example of Figure 13(c), the deformation of the tubular body 11 in the x-axis direction that remained in Figure 10(c) has disappeared, and the correct measurement result shown in Figure 13(a) has been reproduced.

[0045] As described above, the 3D shape measurement system of this embodiment corrects for the displacement of the central axis of the tubular body 11 in the x-axis and z-axis directions in steps S13 and S14. Therefore, this embodiment makes it possible to accurately measure the deformation of the tubular body 11.

[0046] In the example shown in Figure 3, the longitudinal direction of the tubular body 11 is shown to be straight, but this disclosure is not limited to this. For example, the tubular body 11 may be curved at any point in its longitudinal direction, or it may be spirally curved. This disclosure is applicable even to such shapes. That is, the tubular body 11 is not limited to a water cooling tube used in a boiler, but may also be a car muffler, a wire harness, or an electrode rod for a battery.

[0047] (Other embodiments) The analysis device 92 of the present invention can also be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. [Explanation of Symbols]

[0048] 11-1, 11-2, 11-3: Tubular body 12-1, 12-2: Membrane 13-1, 13-2: 91: Measuring device 92: Analysis device

Claims

1. Obtain measurement data of the surface shape of the object to be measured, Using the aforementioned measurement data, the longitudinal central axis of the tubular body in the measurement target is calculated. Using information other than the tubular body obtained from the measurement data, the deviation of the central axis is corrected. Analysis device.

2. The information other than the tubular body is information about the fixing part for fixing the tubular body. The analysis apparatus according to claim 1.

3. The boundary point between the tubular body and the fixing part is calculated, Based on the relative position between the boundary point and the central axis of the tubular body, the deviation of the central axis is corrected. The analysis apparatus according to claim 2.

4. The boundary point is the point at which the curvature of the tubular body changes discontinuously. The analysis apparatus according to claim 3.

5. Using the corrected central axis, the reference shape of the inner surface of the tubular body is calculated. Using the surface shape of the tubular body obtained from the measurement data and the reference shape, the wall thickness of the tubular body is calculated. The analysis apparatus according to claim 1.

6. Using the corrected central axis, the reference shape of the outer surface of the tubular body is calculated. Using the surface shape of the tubular body obtained from the measurement data and the reference shape, the amount of deformation of the tubular body is calculated. The analysis apparatus according to claim 1.

7. A measuring device for measuring the surface shape of the object to be measured, An analysis device according to any one of claims 1 to 6, which acquires measurement data obtained by the aforementioned measuring device, A three-dimensional shape measurement system equipped with the following features.

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