Warpage gauge, inspection system, inspection method, inspection program

Abstract

To provide a strain gauge, an inspection system, an inspection method, and an inspection program, capable of accurately measuring strain or a displacement amount of an object to be measured.SOLUTION: A strain gauge includes a gauge base, a detection unit that is attached to the gauge base and detects strain of an object to be measured as an electric signal, and an image displacement measurement pattern provided in the gauge base.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a strain gauge, an inspection system, an inspection method, and an inspection program.

Background Art

[0002] In the inspection work of measurement objects such as bridges and towers, for example, the strain or displacement amount of the measurement object is measured by the digital image correlation method or the sampling moire method. Patent Document 1 discloses an inspection system for measuring the strain of a measurement object by the digital image correlation method. Patent Document 2 discloses an inspection system for measuring the displacement amount of a measurement object by the sampling moire method.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] It is desired to accurately measure the strain or displacement amount of a measurement object using an image measurement method such as the digital image correlation method and the sampling moire method.

[0005] An object of the present invention is to provide a strain gauge, an inspection system, an inspection method, and an inspection program capable of accurately measuring the strain or displacement amount of a measurement object.

Means for Solving the Problems

[0006] The strain gauge according to the first aspect of the present invention includes a gauge base, a detection unit attached to the gauge base for detecting the strain of a measurement object as an electrical signal, and a pattern for image displacement measurement provided on the gauge base.

[0007] According to the strain gauge according to the first aspect, the strain value or displacement amount calculated based on the displacement of the pattern for image displacement measurement used in the digital image correlation method or the sampling moiré method can be corrected based on the strain value or displacement amount calculated based on the detection result of the strain gauge. Therefore, the strain or displacement amount of the measurement object can be accurately measured.

[0008] The strain gauge according to the second aspect of the present invention is the strain gauge according to the first aspect, wherein the pattern for image displacement measurement is an irregular pattern used in the digital image correlation method or a regular lattice used in the sampling moiré method.

[0009] According to the strain gauge according to the second aspect, the strain or displacement amount of the measurement object can be accurately measured using the digital image correlation method or the sampling moiré method.

[0010] The strain gauge according to the third aspect of the present invention is the strain gauge according to the second aspect, wherein the pattern for image displacement measurement is an irregular pattern used in the digital image correlation method, and the gauge base has an information providing unit that displays information regarding the setting conditions of an imaging device for photographing the pattern for image displacement measurement.

[0011] According to the strain gauge according to the third aspect, since the characteristics of the pattern for image displacement measurement are associated with the setting conditions of the imaging device, the strain or displacement amount of the measurement object can be easily measured using the digital image correlation method.

[0012] The strain gauge according to the fourth aspect of the present invention is the strain gauge according to the third aspect, wherein the information providing unit includes a two-dimensional code or a one-dimensional code.

[0013] According to the strain gauge according to the fourth aspect, information regarding the setting conditions of the imaging device can be easily obtained.

[0014] The inspection system according to the fifth aspect of the present invention includes a strain gauge according to any one of the first to fourth aspects, and an inspection unit that calculates the strain or displacement amount of the measurement object based on the detection result of the strain gauge. The strain gauge includes a gauge base, a detection unit that is attached to the gauge base and detects the strain of the measurement object as an electric signal, and an image displacement measurement pattern provided on the gauge base. The inspection unit includes a calculation unit that calculates a first strain value or a first displacement amount in a reference measurement region based on an image of the image displacement measurement pattern photographed by an imaging device. The calculation unit calculates a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit.

[0015] According to the inspection system according to the fifth aspect, the strain value or displacement amount of a measurement region other than the reference measurement region can be accurately measured using the correction coefficient.

[0016] The inspection system according to the sixth aspect of the present invention is the inspection system according to the fifth aspect, wherein the calculation unit calculates the strain value or displacement amount of a plurality of measurement regions other than the reference measurement region based on an image of the image displacement measurement pattern photographed by the imaging device, and calculates a strain distribution value or a displacement amount distribution by correcting the calculated strain value or displacement amount of the plurality of measurement regions based on the correction coefficient.

[0017] According to the inspection system according to the sixth aspect, the strain distribution value or the displacement amount distribution can be accurately calculated.

[0018] The inspection method according to the seventh aspect of the present invention is an inspection method for measuring the strain or displacement amount of a measurement object using a strain gauge, wherein the strain gauge includes a gauge base, a detection unit attached to the gauge base for detecting the strain of the measurement object as an electrical signal, and an image displacement measurement pattern provided on the gauge base. The method includes calculating a first strain value or a first displacement amount in a reference measurement region based on an image of the image displacement measurement pattern taken by an imaging device, and calculating a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit.

[0019] According to the inspection method according to the seventh aspect, the strain value or displacement amount of a measurement region other than the reference measurement region can be accurately measured using the correction coefficient.

[0020] The inspection program according to the eighth aspect of the present invention is an inspection program for measuring the strain or displacement amount of a measurement object using a strain gauge, wherein the strain gauge includes a gauge base, a detection unit attached to the gauge base for detecting the strain of the measurement object as an electrical signal, and an image displacement measurement pattern provided on the gauge base. The program causes a computer to calculate a first strain value or a first displacement amount in a reference measurement region based on an image of the image displacement measurement pattern taken by an imaging device, and calculate a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit.

[0021] According to the above inspection program, the strain value or displacement amount of a measurement region other than the reference measurement region can be accurately measured using the correction coefficient.

Effects of the Invention

[0022] According to the strain gauge, inspection system, inspection method, and inspection program of the present invention, the strain or displacement amount of a measurement object can be accurately measured.

Brief Description of the Drawings

[0023]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0024] Hereinafter, an inspection system according to an embodiment of the present invention will be described with reference to the drawings.

[0025] <1. Overall Configuration of the Inspection System> FIG. 1 is a schematic configuration diagram of the inspection system 10. The inspection system 10 is configured to accurately measure the strain or displacement amount of the object to be measured. The object to be measured is, for example, the upper die of a forging press, the movable die of an injection molding machine, or an infrastructure structure. The infrastructure structure is, for example, an elevated road, a bridge, a railway bridge, or a tunnel. The inspection system 10 includes a strain gauge 20, a strain measuring instrument 30, an inspection unit 40, and an imaging device 50.

[0026] <2. Hardware Configuration of the Inspection System> <2-1. Configuration of the Strain Gauge> FIG. 2 is a front view of the strain gauge 20. The strain gauge 20 has a gauge base 21, a detection unit 22, an image displacement measurement pattern 23, and an information providing unit 24.

[0027] As the gauge base 21, a gauge base of a known strain gauge can be used. The gauge base 21 has a front surface 21A and a back surface 21B. The gauge base 21 is, for example, coated with an adhesive on the back surface 21B and joined to the object to be measured via the adhesive. The gauge base 21 is, for example, made of a resin material.

[0028] The detection unit 22 can use a known detection unit of a strain gauge. In the present embodiment, the detection unit 22 has a resistance wire or a photo-etched resistance foil on the grid, and lead wires and the like. The detection unit 22 outputs the strain of the measurement object as an electric signal. The detection unit 22 is attached to the surface 21A of the gauge base 21.

[0029] The image displacement measurement pattern 23 is a pattern used in image measurement methods such as the digital image correlation method and the sampling moiré method. In the present embodiment, the image displacement measurement pattern 23 is an irregular pattern used in the digital image correlation method. The image displacement measurement pattern 23 may be a regular grid used in the sampling moiré method. The image displacement measurement pattern 23 is formed substantially over the entire surface 21A of the gauge base 21.

[0030] The information providing unit 24 displays information regarding the setting conditions of the imaging device 50 (see FIG. 1) that captures the image displacement measurement pattern 23. In the present embodiment, since the image displacement measurement pattern 23 is an irregular pattern, the pattern of the image displacement measurement pattern 23 is different for each strain gauge 20. When changing the setting conditions of the imaging device 50 for each strain gauge 20 to be used, the work is complicated. In the present embodiment, since the information regarding the setting conditions of the imaging device 50 is displayed in advance on the gauge base 21, the setting conditions of the imaging device 50 can be easily set. The information regarding the setting conditions of the imaging device 50 includes, for example, the distance between the imaging device 50 and the strain gauge 20 and information regarding the calibration of the lens. The specific configuration of the information providing unit 24 can be arbitrarily selected. In the present embodiment, the information providing unit 24 is a two-dimensional code. The information providing unit 24 may be a one-dimensional code. The information providing unit 24 is formed, for example, in a portion of the surface 21A of the gauge base 21 where the image displacement measurement pattern 23 is not formed.

[0031] <2-2. Configuration of the strain measuring instrument> The strain measuring device 30 shown in FIG. 1 is connected to the lead wires of the detection unit 22 of the strain gauge 20. The strain measuring device 30 calculates a strain value based on the detection result of the detection unit 22 (see FIG. 2). The strain measuring device 30 transmits the calculated strain value to the inspection unit 40.

[0032] <2-3. Configuration of the inspection unit> The inspection unit 40 shown in FIG. 1 calculates the strain or displacement amount of the measurement object based on the detection result of the strain gauge 20. The inspection unit 40 includes a main body 41, an input device 42, and an output device 43. The main body 41 includes a storage device 41A and a control device 41B. The storage device 41A and the control device 41B are connected so as to be able to communicate via a bus 44. The storage device 41A is, for example, a hard disk or a solid state drive. The storage device 41A stores one or more programs (hereinafter referred to as "inspection program 41P") related to the calculation of the strain or displacement amount of the measurement object.

[0033] The control device 41B includes a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc., and executes functions described later. The control device 41B executes the inspection program 41P stored in the storage device 41A in response to a request from the input device 42. By the control device 41B executing the inspection program 41P, one or more functional blocks described later are constructed in the inspection unit 40.

[0034] The input device 42 is, for example, a keyboard and is connected to the main body 41. The output device 43 is, for example, a liquid crystal display and is connected to the main body 41 so as to be able to receive a signal output from the main body 41. Note that the main body 41, the input device 42, and the output device 43 may be integrally configured like a notebook personal computer.

[0035] <2-3. Configuration of the imaging device> The imaging device 50 is configured to be able to photograph the image displacement measurement pattern 23 (see FIG. 2). In the present embodiment, the imaging device 50 is a camera. The imaging device 50 photographs the image displacement measurement pattern 23 at regular intervals. In the present embodiment, the imaging device 50 is connected so as to be able to perform wireless communication or wired communication with the inspection unit 40. The images of the image displacement measurement pattern 23 taken at regular intervals by the imaging device 50 are transmitted to the inspection unit 40 and stored, for example, in the storage device 41A.

[0036] <3. Software Configuration of Inspection System> The functional blocks configured by the control device 41B executing the inspection program 41P stored in the storage device 41A include, for example, a calculation unit 41X. By constructing functional blocks such as the calculation unit 41X in the inspection unit 40, an inspection process for calculating the strain or displacement amount of the measurement object is executed.

[0037] <4. Inspection Process> With reference to FIG. 3, an example of the processing procedure of the inspection process will be described. The calculation unit 41X discloses the inspection process, for example, based on the fact that the strain gauge 20 is attached to the measurement object and the imaging of the image displacement measurement pattern 23 is started by the imaging device 50.

[0038] In step S11, the calculation unit 41X detects the movement of the pixel positions based on the image of the image displacement measurement pattern 23.

[0039] In step S12, the calculation unit 41X calculates the displacement amount of the pixel group in the reference measurement area based on the movement amount of each pixel. The reference measurement area is an area in the image displacement measurement pattern where the strain of the measurement object can be detected by the strain gauge 20.

[0040] In step S13, the calculation unit 41X calculates the strain value (hereinafter referred to as "first strain value XA") of the reference measurement area based on the displacement amount of the pixel group in the reference measurement area calculated in step S12.

[0041] In step S14, the calculation unit 41X calculates a correction coefficient α for correcting the first distortion value XA based on the distortion value of the reference measurement region (hereinafter referred to as "second distortion value XB") detected by the detection unit 22. The correction coefficient α is calculated by the following formula (1). Correction coefficient α = second distortion value XB / first distortion value XA ··· (1)

[0042] In step S15, the calculation unit 41X calculates the displacement amounts of the pixel groups in a plurality of regions other than the reference measurement region in the image displacement measurement pattern 23 based on the image of the image displacement measurement pattern 23.

[0043] In step S16, the calculation unit 41X calculates the distortion values (hereinafter referred to as "third distortion values XC") of a plurality of regions other than the reference measurement region based on the displacement amounts calculated in step S15, respectively.

[0044] In step S17, the calculation unit 41X corrects the third distortion value XC by multiplying the third distortion value XC by the correction coefficient α. By completing step S17, the third distortion value XC in a plurality of measurement regions can be measured, so that the distortion distribution value can be calculated.

[0045] <5. Effects of this Embodiment> According to the inspection system 10 configured as described above, the following effects can be obtained.

[0046] <5-1> Since the third distortion value XC is corrected using the correction coefficient α, the third distortion value XC can be accurately measured.

[0047] <5-2> Generally, the random pattern used in the digital image correlation method is applied by spraying it onto the object to be measured. The operation of applying the random pattern to the object to be measured is complicated because there are various constraints such as the limitation on the number of random patterns with respect to the number of pixels. According to the inspection system 10 of the present embodiment, since the image displacement measurement pattern 23 is previously applied to the gauge base 21, the operator only needs to attach the strain gauge 20 to the object to be measured. Therefore, the measurement of the strain of the object to be measured can be easily performed.

[0048] <5-3> Since the strain gauge 20 has the information providing unit 24, the characteristics of the image displacement measurement pattern 23 and the setting conditions of the imaging device 50 are associated with each other. Therefore, the setting conditions of the imaging device 50 can be easily set.

[0049] <5-4> Since the strain value of the region where the image displacement measurement pattern 23 is formed can be accurately calculated by one strain gauge 20, the configuration of the inspection system 10 can be simplified.

[0050] <6. Modification Example> The above embodiment is an example of a form that the strain gauge, inspection system, inspection method, and inspection program related to the present invention can take, and is not intended to limit that form. The strain gauge, inspection system, inspection method, and inspection program related to the present invention can take forms different from the forms exemplified in the embodiment. An example thereof is a form in which a part of the configuration of the embodiment is replaced, changed, or omitted, or a new configuration is added to the embodiment. Modification examples of the embodiment are shown below.

[0051] In the above embodiment, the calculation unit 41X calculates the strain value of the measurement region other than the reference measurement region, in other words, the third strain value XC, but the displacement amount of the measurement region other than the reference measurement region may be calculated.

[0052] For example, in step S12 of the inspection process, the calculation unit 41X calculates the first displacement amount ΔXA of the reference measurement area. Next, in step S14 of the inspection process, the calculation unit 41X calculates a correction coefficient β for correcting the first displacement amount ΔXA based on the second displacement amount ΔXB of the reference measurement area detected by the detection unit 22. The correction coefficient β is calculated by the following formula (2). Correction coefficient β = Second displacement amount ΔXB / First displacement amount ΔXA ··· (2)

[0053] Next, in step S15 of the inspection process, the calculation unit 41X calculates the third displacement amount ΔXC of each pixel group of a plurality of areas other than the reference measurement area in the image displacement measurement pattern 23 based on the image of the image displacement measurement pattern 23. Next, in step S17 of the inspection process, the calculation unit 41X corrects the third displacement amount ΔXC by multiplying the third displacement amount ΔXC by the correction coefficient β. When step S17 is completed, the third displacement amount ΔXC in a plurality of measurement areas can be measured, so that the displacement amount distribution can be calculated.

Explanation of reference numerals

[0054] 10: Inspection system 20: Strain gauge 21: Gauge base 22: Detection unit 23: Image displacement measurement pattern 24: Information providing unit 41P: Inspection program 41X: Calculation unit 50: Imaging device

Claims

1. A gauge base, a detection unit attached to the gauge base for detecting the strain of the object to be measured as an electrical signal, and an image displacement measurement pattern provided on the gauge base. A strain gauge.

2. The image displacement measurement pattern is an irregular pattern used in the digital image correlation method or a regular lattice used in the sampling moiré method. The strain gauge according to claim 1.

3. The image displacement measurement pattern is an irregular pattern used in the digital image correlation method, and the gauge base has an information providing unit for displaying information regarding the setting conditions of an imaging device for photographing the image displacement measurement pattern. The strain gauge according to claim 2.

4. The information providing unit includes a two-dimensional code or a one-dimensional code. The strain gauge according to claim 3.

5. A strain gauge according to any one of claims 1 to 4, and an inspection unit for calculating the strain or displacement amount of the object to be measured based on the detection result of the strain gauge. The inspection system includes: The strain gauge is a gauge base, a detection unit attached to the gauge base for detecting the strain of the object to be measured as an electrical signal, and an image displacement measurement pattern provided on the gauge base. The inspection unit is equipped with a calculation unit for calculating a first strain value or a first displacement amount in a reference measurement region based on an image of the image displacement measurement pattern photographed by an imaging device. The calculation unit calculates a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit. An inspection system.

6. The calculation unit is based on an image of the image displacement measurement pattern photographed by the imaging device, calculates the strain value or displacement amount of a plurality of measurement regions other than the reference measurement region, and calculates a strain distribution value or a displacement amount distribution by correcting the calculated strain value or displacement amount of the plurality of measurement regions based on the correction coefficient. The inspection system according to claim 5.

7. An inspection method for measuring the strain or displacement amount of an object to be measured using a strain gauge, wherein the strain gauge is a gauge base, a detection unit attached to the gauge base for detecting the strain of the object to be measured as an electrical signal, and an image displacement measurement pattern provided on the gauge base. Based on the image of the pattern for image displacement measurement captured by the imaging device, calculating a first strain value or a first displacement amount in a reference measurement region; calculating a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit; and An inspection method. **Claim 8** An inspection program for measuring the strain or displacement amount of a measurement object using a strain gauge, wherein the strain gauge comprises a gauge base, a detection unit attached to the gauge base for detecting the strain of the measurement object as an electrical signal, and a pattern for image displacement measurement provided on the gauge base; Based on the image of the pattern for image displacement measurement captured by the imaging device, calculating a first strain value or a first displacement amount in a reference measurement region; causing a computer to execute a step of calculating a correction coefficient for correcting the first strain value or the first displacement amount based on a second strain value or a second displacement amount of the reference measurement region detected by the detection unit; An inspection program.

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