JP7504250B1 - Inspection system and inspection method - Google Patents

Abstract

[Problem] To realize an inspection system and inspection method that can easily obtain appropriate inspection results regardless of the position and shape of the object to be inspected. [Solution] The system includes a thermal image capturing device 21 capable of capturing a thermal image of an object to be inspected to which a coating material has been applied, a storage device 22b that stores a reference image, which is a thermal image of an object to be inspected to which a coating material has been normally applied, and arithmetic units 22a and 32a, and the arithmetic units 22a and 32a are capable of performing a position identification function for identifying the position of the object to be inspected, an image capturing function for capturing a thermal image of the object to be inspected, a position adjustment function for performing at least one of adjusting the relative position between the object to be inspected and the thermal image capturing device 21 and adjusting the position of the object to be inspected in the captured thermal image, and a judgment function for judging the state of application of the coating material on the object to be inspected based on the reference image and the thermal image captured by the image capturing function. [Selected Figure] Figure 2

Description

The present invention relates to an inspection system and an inspection method for inspecting an object to be inspected that has a coating applied thereto.

Various coatings may be applied to articles such as car bodies in order to impart certain functions. In the case of car bodies, examples of coatings include anti-rust wax that is applied to prevent rust, and urethane foam that is applied to impart soundproofing and vibration-proofing properties.

When a coating material is applied to an article, the quality of the coating directly impacts the quality of the product. For this reason, various methods for inspecting the coating condition of coating materials have been studied. For example, JP 2014-92371 A (Patent Document 1) discloses a coating inspection system equipped with an infrared thermograph that captures the coating area where the coating material is applied. The invention of Patent Document 1 instantly displays the temperature distribution of the coating area, allowing the applicator to check the inspection results directly and in a timely manner.

JP 2014-92371 A

However, with the technology of Patent Document 1, the positional relationship between the infrared thermograph and the object being inspected is fixed, so depending on the position where the coating material is applied, it may be difficult to obtain a thermal image that makes it easy to understand the condition of that position. Also, when the positions and shapes of the objects to be inspected vary widely, it is difficult to obtain thermal images suitable for inspection for all of them, and it may be difficult to obtain appropriate inspection results.

Therefore, there is a need to develop an inspection system and method that can easily obtain appropriate inspection results regardless of the position and shape of the object being inspected.

The first inspection system according to the present invention is characterized in that it comprises a thermal imaging device that captures a thermal image of the side of an inspection object opposite to the side to which the coating material has been applied, a memory device that stores a reference image which is a thermal image of the inspection object on which the coating material has been normally applied, a position identification means that identifies the position of the inspection object, a position adjustment means that adjusts the relative position of the inspection object and the thermal imaging device based on the position of the inspection object identified by the position identification means, and a judgment means that judges the coating condition of the inspection object by comparing the thermal image of the opposite side of the inspection object captured by the thermal imaging device after the position has been adjusted by the position adjustment means with the reference image.
The second inspection system of the present invention is characterized in that it comprises a thermal image capturing device that captures a thermal image of the side of an inspection object coated with a coating material opposite the side to which the coating material is applied, a memory device that stores a reference image, which is a thermal image of the inspection object on which the coating material has been normally applied, a position identification means that identifies the position of the inspection object, a position adjustment means that adjusts the position of the inspection object in the thermal image captured by the thermal image capturing device based on the position of the inspection object identified by the position identification means, and a judgment means that judges the coating condition of the inspection object by comparing the thermal image position-adjusted by the position adjustment means with the reference image.

The first inspection method according to the present invention is characterized by comprising a position identification step of identifying a position of an object to be inspected on which a coating material has been applied ; a position adjustment step of adjusting a relative position between the object to be inspected and a thermal image photographing device based on the position of the object to be inspected identified in the position identification step ; an imaging step of photographing a thermal image of the side of the object to be inspected opposite to the side to which the coating material has been applied by the thermal image photographing device after the position has been adjusted by the position adjustment step ; and a determination step of determining the coating condition of the object to be inspected by comparing the thermal image of the opposite side of the object to be inspected photographed by the imaging step with a reference image which is a thermal image of the object to be inspected on which the coating material has been normally applied.
The second inspection method of the present invention is characterized by comprising a position identification step of identifying the position of an object to be inspected on which a coating material has been applied; an imaging step of capturing a thermal image of the side of the object to be inspected opposite the side to which the coating material has been applied using a thermal image imaging device; a position adjustment step of adjusting the position of the object to be inspected in the thermal image captured by the imaging step based on the position of the object to be inspected identified by the position identification step; and a determination step of determining the coating condition of the object to be inspected by comparing the thermal image whose position has been adjusted by the position adjustment step with a reference image, which is a thermal image of the object to be inspected on which the coating material has been normally applied.

With these configurations, the relative positional relationship between the object to be inspected and the thermal image capture device is adjusted, or the position of the object to be inspected on the thermal image is adjusted, and then a thermal image is captured, and the coating condition of the coating material is determined based on the thermal image, making it easier to obtain appropriate inspection results regardless of the position and shape of the object to be inspected.

Further features and advantages of the present invention will become more apparent from the following description of exemplary and non-limiting embodiments, which are given with reference to the drawings.

1 is a diagram showing an overview of an inspection system according to an embodiment; FIG. 1 is a block diagram showing components of an inspection system according to an embodiment. FIG. 2 is a flow chart showing a procedure of an inspection method according to an embodiment. FIG. 13 is a diagram showing an overview of an inspection system according to a modified example.

Embodiments of an inspection system and an inspection method according to the present invention will be described with reference to the drawings. Below, an example will be described in which the inspection system according to the present invention is applied to an inspection system 1 that inspects a vehicle body B (an example of an object to be inspected) coated with anti-rust wax (an example of an object to be coated).

The vehicle body B has bag-shaped parts (bag-shaped parts) on, for example, the door panels and the hood. Because it is difficult to visually access the bag-shaped parts, it is time-consuming to check the state of application of the rust-preventive wax to the bag-shaped parts visually or by using a visible light image. For this reason, in the past, there were cases where the state of application of the rust-preventive wax to the bag-shaped parts was insufficient. The inspection system 1 and inspection method according to this embodiment provide an inspection method that is effective even for bag-shaped parts.

In the following, an example is described in which a vehicle body B to which anti-rust wax has been applied in a previous process booth (not shown) is brought into an inspection booth in which an inspection system 1 is installed and undergoes inspection. The anti-rust wax is applied to the vehicle body B after being heated to above room temperature in the previous process. This is because the viscosity of the anti-rust wax is reduced by heating, making it easier to apply.

[Configuration of the inspection system]
The inspection system 1 includes a thermal image capturing unit 2, a three-dimensional measuring unit 3, a support device 4, and a control device 5 (an example of a computing device) (FIGS. 1 and 2).

The thermal image capturing unit 2 has a thermal image capturing device 21 capable of capturing thermal images of the vehicle body B, and a computer 22. Both the thermal image capturing device 21 and the computer 22 can use known hardware. The computer 22 has an arithmetic unit 22a and a storage device 22b. The arithmetic unit 22a performs arithmetic processing related to the control of the thermal image capturing unit 2. The storage device 22b stores data necessary for the control, and in particular stores a thermal image of the vehicle body B on which anti-rust wax has been properly applied as a reference image. The reference image was captured using the thermal image capturing unit 2 of a vehicle body B that has been determined to have anti-rust wax properly applied by manual inspection using conventional methods.

The three-dimensional measurement unit 3 has a measuring device 31 capable of measuring the vehicle body B three-dimensionally, and a computer 32. Both the measuring device 31 and the computer 32 can use known hardware. The computer 32 has an arithmetic device 32a and a storage device 32b. The arithmetic device 32a realizes arithmetic processing related to the control of the three-dimensional measurement unit 3. The storage device 32b stores data necessary for the control, and in particular stores master data based on the structure of the vehicle body B.

The support device 4 has a first robot 41 that supports the thermal image capture device 21, and a second robot 42 that supports the measurement device 31. Known industrial robots can be used as the first robot 41 and the second robot 42. Each of the first robot 41 and the second robot 42 has a controller (not shown; an example of a control device) that controls the operation of each robot.

The control device 5 is a device that comprehensively controls the thermal image capture unit 2, the three-dimensional measurement unit 3, and the support device 4, and is implemented, for example, as a PLC (programmable logic controller). Specifically, it issues commands to start the operation of the first robot 41 and the second robot 42, controls triggers for capture by the thermal image capture unit 2, controls triggers for measurement by the three-dimensional measurement unit 3, and so on. Therefore, the control device 5 is capable of communicating with the thermal image capture unit 2, the three-dimensional measurement unit 3, and the support device 4.

[Functions and inspection methods of the computing device]
Next, we will explain the functions of the inspection system 1. The following explains the functions of the programs that run on the inspection system 1 according to the procedure of the method for inspecting the vehicle body B using the inspection system 1. In other words, the following explanation also explains an embodiment of the inspection method according to the present invention (FIG. 3).

The inspection system 1 can realize a position identification function for identifying the position of the vehicle body B, a position adjustment function for adjusting the relative position between the vehicle body B and the thermal image capture device 21, an image capture function for capturing a thermal image of the vehicle body B, and a judgment function for judging the application state of the rust-preventive wax on the vehicle body B.

(1) Position Identification Function (Position Identification Step #10)
The position identification function is a function for identifying the position of the vehicle body B. The calculation processing related to the position identification function is realized by the calculation device 32a of the three-dimensional measurement unit 3. The position identification function identifies the position of the vehicle body B based on a visible light image of the vehicle body B captured by the three-dimensional measurement unit 3 (measurement device 31). Note that master data based on the structure of the vehicle body B is used as data to be compared with the captured visible light image. As described above, the master data is stored in the storage device 32b of the three-dimensional measurement unit 3.

First, the vehicle body B is photographed using the measuring device 31. At this time, the controller of the second robot 42 controls each axis of the second robot 42 so that the measuring device 31 is moved so that at least a portion of the vehicle body B necessary for identifying the position is included in the visible light image. The control amount of the second robot 42 at this time is associated with the visible light image. It is preferable to roughly align the position of the vehicle body B before photographing the vehicle body B. For example, when the vehicle body B is carried into the inspection booth by a transport device, if the stopping position of the transport device is the same every time, the vehicle body B will be carried into roughly the same position every time. In this case, the identification of the position of the vehicle body B by the position identification function is positioned as a fine adjustment based on the assumption that the rough position of the vehicle body B is constant, and it is easy to precisely identify the position of the vehicle body B.

Next, feature points present on vehicle body B are identified based on the master data. Feature points refer to parts of vehicle body B that are characteristic and relatively easy to identify on the visible light image, such as holes provided in vehicle body B or edges of vehicle body B. The number of feature points identified is arbitrary, but it is preferable that there are multiple feature points.

Finally, the positions of the feature points are identified in the captured visible light image, and each part of the vehicle body B shown in the visible light image is associated with the coordinates of each part of the vehicle body B in the master data. By performing this association, the relative position of each part of the vehicle body B with respect to the three-dimensional measuring unit 3 can be identified. Note that a reference position for the position where the vehicle body B should be placed may be determined in advance, and the position of the vehicle body B may be identified as the degree of deviation of the identified position from the reference position.

(2) Position Adjustment Function (Position Adjustment Function Step #20)
The position adjustment function is a function for adjusting the relative position between the vehicle body B and the thermal image photographing device 21 based on the position of the vehicle body B identified by the position identification function. The position adjustment function is realized by the controller of the first robot 41. The controller of the first robot 41 controls each axis of the first robot 41 to move the thermal image photographing device 21 so that the position of the vehicle body B in the thermal image photographed by the thermal image photographing device 21 is the same as the position of the vehicle body B in the reference image. In other words, the first robot 41 is controlled so that the relative position between the vehicle body B and the thermal image photographing device 21 when the reference image is photographed is reproduced, that is, so that the angle of view of the reference image is reproduced in the thermal image to be photographed. The control amount of the first robot 41 at this time is determined based on the correction amount sent to the first robot 41 from the three-dimensional measurement unit 3 (the calculation device 32a) via the control device 5.

(3) Photography function (photography process #30)
The photographing function is a function for photographing a thermal image of the vehicle body B using the thermal image photographing device 21 after the relative position between the vehicle body B and the thermal image photographing device 21 is adjusted by the position adjustment function. The photographing function is realized by the arithmetic device 23 of the thermal image photographing unit 2. As described above, since the relative position between the vehicle body B and the thermal image photographing device 21 when the reference image was photographed is reproduced by the position adjustment function, the position of the vehicle body B in the obtained thermal image becomes the same as the position of the vehicle body B in the reference image. Therefore, it is possible to photograph a thermal image that can be directly compared with the reference image.

As mentioned above, the anti-rust wax is heated to a temperature higher than room temperature before being applied, so the temperature rises at the locations of car body B where the anti-rust wax has been applied. Therefore, the locations of car body B where the anti-rust wax has been applied are detected in the thermal image as locations with a higher temperature than the surrounding area. Using this, if the temperature of the location where the anti-rust wax should be applied is lower than the expected temperature, it can be assumed that the anti-rust wax has not been applied or has been applied insufficiently. The judgment function described below judges the application state of the anti-rust wax using the above principle.

Here, the rise in temperature caused by applying the anti-rust wax is not limited to the surface on which the anti-rust wax is applied, but also extends to the opposite surface. This is because the heat contained in the anti-rust wax is transferred from the applied surface to the opposite surface. By focusing on this phenomenon, it is possible to determine the state of application of the anti-rust wax to the bag-shaped portion, without directly inspecting the bag-shaped portion, by inspecting the opposite surface of the bag-shaped portion. In other words, if the bag-shaped portion is located on the back side of vehicle body B, instead of photographing the bag-shaped portion directly, it is sufficient to photograph the front surface of vehicle body B, which is opposite the bag-shaped portion.

In light of the above, the imaging function captures images so that the front surface of the vehicle body B, which is the opposite surface of the bag-shaped portion to be inspected, is included in the thermal image. Furthermore, the position adjustment function adjusts the relative position between the vehicle body B and the thermal image imaging device 21 so that a thermal image including the opposite surface of the bag-shaped portion can be captured. Similar control is also performed when capturing a reference image.

(4) Judgment function (judgment step #40)
The judgment function is a function for judging the application state of the anti-rust wax on the vehicle body B based on the reference image and the thermal image captured by the photographing function (hereinafter referred to as the photographed image). The judgment function is realized by the calculation device 22a of the thermal image photographing unit 2. As described above, the phenomenon in which the temperature of the vehicle body B rises due to the application of the anti-rust wax is utilized to judge whether the application of the anti-rust wax has been performed normally on the areas where the wax should be applied. As described above, the reference image is stored in the memory device 22b of the thermal image photographing unit 2.

Specifically, the reference image and the captured image are compared. The method of comparison is not limited, but examples include a method of comparing the temperature of each pixel in the reference image and the captured image, counting the number of pixels that differ between the two, and judging that there is an abnormality if the counted number exceeds a predetermined threshold value, or a method of calculating the temperature difference between high-temperature parts (parts where anti-rust wax is applied) and low-temperature parts (parts where anti-rust wax is not applied) for each of the reference image and the captured image, and judging whether the image is good or bad based on a comparison of the temperature differences. Also, the maximum temperature, minimum temperature, average temperature, etc. in each image may be compared.

In addition, a judgment may be made taking into consideration the difference in the environment when the reference image and the photographed image were acquired. For example, the time required from the completion of application of the anti-rust wax to the inspection (until the photographed image is taken), the temperature of the vehicle body B before the anti-rust wax is applied, the specific heat and plate thickness of the vehicle body B, the temperature, specific heat, and amount of the anti-rust wax applied, as well as the room temperature, wall temperature, floor temperature, and ceiling temperature of the paint booth and the inspection booth, etc. may be taken into consideration. Note that when these factors are taken into consideration, information related to the factors must be input to the calculation device 22a. For example, a configuration may be adopted in which a thermometer is installed in the inspection booth, and the measurement value of the thermometer is input to the calculation device 22a as the room temperature of the inspection booth.

If it is not possible to include all of the parts of vehicle body B to be inspected in a single thermal image, the inspection may be performed by capturing multiple thermal images of each part of vehicle body B. In this case, the position identification function, position adjustment function, photographing function, and judgment function need only be realized a number of times that allows all of the thermal images to be captured. It is not necessary that each function is realized the same number of times. For example, it is usually sufficient to realize the position identification function once.

The results of the judgment can be used as appropriate from the perspective of improving the quality of the vehicle body B. For example, if an area where the anti-rust wax coating is insufficient is identified, then repainting that area will allow the production of a vehicle body B of normal quality. Furthermore, if the phenomenon of insufficient anti-rust wax coating is detected multiple times, measures such as inspecting the equipment can be taken in consideration of the possibility that there may be a problem somewhere in the process.

[Modifications]
(Modification of the Support Device)
In the above embodiment, the first robot 41 supporting the thermal image capturing device 21 and the second robot 42 supporting the measuring device 31 are separate from each other. As a modified example, the thermal image capturing device 21 and the measuring device 31 may be supported by a single robot 43 (FIG. 4).

(Modification of Position Adjustment Function)
In the above embodiment, the relative position between the vehicle body B and the thermal image photographing device 21 is adjusted (position adjustment function) based on the position of the vehicle body B identified by the position identification function, and then a thermal image of the vehicle body B is photographed (photographing function) has been described as an example. As a modified example, instead of physically adjusting the relative position between the vehicle body B and the thermal image photographing device 21, the thermal image photographed by the thermal image photographing device 21 may be processed by software to adjust the position of the vehicle body B in the thermal image. In this case, the position adjustment function is realized after the position identification function and the photographing function, and the order of the position identification function and the photographing function does not matter.

For example, if the position of vehicle body B identified by the position identification function is shifted by 10 mm in a certain direction from the position of vehicle body B in the reference image, processing is performed to shift vehicle body B in the thermal image captured by the thermal image capture device 21 by 10 mm in that direction, and the processed thermal image is provided to the judgment function.

In addition, both the adjustment of the relative position between the vehicle body B and the thermal image capture device 21 (physical adjustment) and the adjustment of the position of the vehicle body B on the thermal image (software adjustment) may be performed. In other words, the position adjustment function is a function that performs at least one of the following: adjusting the relative position between the object to be inspected and the thermal image capture device before capturing images by the capture function, based on the position of the object to be inspected identified by the position identification function, and adjusting the position of the object to be inspected in the thermal image captured by the capture function.

Other embodiments
Finally, other embodiments of the inspection system and inspection method according to the present invention will be described. Note that the configurations disclosed in the following embodiments can be combined with the configurations disclosed in other embodiments as long as no contradiction occurs.

In the above embodiment, an example has been described in which the inspection system 1 includes a three-dimensional measuring unit 3, and the position of the vehicle body B is identified based on three-dimensional measurement by the measuring device 31 in the position identification function. However, the present invention is not limited to a means for identifying the position of the object to be inspected. The present invention may use, for example, a visible light image as a component used in the position identification function. Furthermore, even when performing three-dimensional measurement as in the above embodiment, a configuration in which the measuring device can be moved using a robot as in the above embodiment is not essential.

In the above embodiment, an example has been described in which a vehicle body B coated with anti-rust wax in a previous process booth (not shown) is brought into an inspection booth in which an inspection system 1 is installed and inspected. However, the present invention is also applicable to cases where inspection is performed in the same location as the application of the coating material. In this case, if the position of the inspection object (which is the object to be coated at the time of application) is identified when the coating is performed, and the inspection proceeds directly after coating without moving the inspection object, the position of the inspection object may be identified based on the position of the inspection object identified in the coating process.

In the above embodiment, a configuration has been described in which the thermal imaging device 21 can be moved three-dimensionally by the first robot 41 that supports the thermal imaging device 21. However, in the present invention, as long as the position adjustment function can adjust the relative position between the inspection object and the thermal imaging device, the specific device configuration is not limited. For example, instead of the first robot 41 in the above embodiment, a slider may be provided and the thermal imaging device may be installed in a manner that allows it to move on the slider. Also, instead of or in addition to moving the thermal imaging device, the relative position between the inspection object and the thermal imaging device may be adjusted by moving the inspection object.

In the above embodiment, the photographing function has been described as an example of a configuration in which an image of the front surface of the vehicle body B, which is the surface opposite the bag-shaped portion to which the anti-rust wax is applied, is photographed. However, in the present invention, the surface to which the coating material is applied may also be photographed directly.

In the above embodiment, a configuration for inspecting the application state of anti-rust wax has been described as an example. However, like the above embodiment, the present invention can also be applied to inspect the application state of foaming agents, adhesives, paints, insulating materials, sealants, and other applied materials.

In the above embodiment, an example has been described in which the computational processes related to the position identification function, position adjustment function, photographing function, and judgment function are shared by the computation device 22a of the thermal image photographing unit 2, the computation device 32a of the three-dimensional measurement unit 3, and the controller of the first robot 41. However, in the inspection system according to the present invention, there may be one or more computation devices that realize the position identification function, position adjustment function, photographing function, and judgment function.

As for other configurations, it should be understood that the embodiments disclosed in this specification are illustrative in all respects and that the scope of the present invention is not limited thereto. Those skilled in the art will easily understand that appropriate modifications are possible without departing from the spirit of the present invention. Therefore, other embodiments that are modified without departing from the spirit of the present invention are naturally included in the scope of the present invention.

1: Inspection system 21: Thermal image capturing device 22a: Computing device 22b: Storage device 32a: Computing device 5: Control device

Claims (7)

a thermal image capturing device for capturing a thermal image of a surface of an object to be inspected that is opposite to a surface to which a coating material is applied ;
a storage device that stores a reference image, which is a thermal image of the inspection object on which the coating material is normally applied;
A position identification means for identifying the position of the inspection object;
a position adjusting means for adjusting a relative position between the inspection object and the thermal image capturing device based on the position of the inspection object identified by the position identifying means ;
an inspection system comprising: a judgment means for judging the coating state of the object to be inspected by comparing a thermal image of the opposite surface of the object to be inspected taken by the thermal image photographing device with a reference image after the object has been positioned by the position adjustment means. a thermal image capturing device for capturing a thermal image of a surface of an object to be inspected that is opposite to a surface to which a coating material is applied ;
a storage device that stores a reference image, which is a thermal image of the inspection object on which the coating material is normally applied;
A position identification means for identifying the position of the inspection object ;
a position adjusting means for adjusting a position of the inspection object in the thermal image captured by the thermal image capturing device based on the position of the inspection object identified by the position identifying means ;
and a determination means for determining a coating state of the object to be inspected by comparing the thermal image adjusted by the position adjustment means with the reference image . The thermal imaging device further includes a support device for movably supporting the thermal imaging device,
2. The inspection system according to claim 1, wherein the position adjustment means moves the thermal image capturing device by means of the support device. Further comprising a visible light imaging device for capturing a visible light image of the inspection object,
3. The inspection system according to claim 1, wherein the position specifying means specifies the position of the object to be inspected based on a visible light image captured by the visible light imaging device. 3. The inspection system according to claim 1, wherein the position specifying means specifies the position of the object to be inspected based on a position of the object to be inspected that is specified when the coating material is applied to the object to be inspected. a position identifying step of identifying a position of the test object to which the coating material is applied;
a position adjustment step of adjusting a relative position between the inspection object and the thermal image capturing device based on the position of the inspection object identified in the position identification step ;
an imaging step of imaging a thermal image of a surface of the inspection object opposite to a surface on which the coating material is applied by the thermal image imaging device after the position is adjusted by the position adjustment step ;
and a determination step of determining the coating condition of the object to be inspected by comparing the thermal image of the opposite surface of the object to be inspected photographed in the photographing step with a reference image, which is a thermal image of the object to be inspected on which the coating has been normally applied. a position identifying step of identifying a position of the test object to which the coating material is applied;
an imaging step of imaging a thermal image of a surface of the object to be inspected opposite to the surface to which the coating material is applied by a thermal image imaging device;
a position adjusting step of adjusting a position of the inspection object in the thermal image captured in the photographing step based on the position of the inspection object identified in the position identifying step;
and a determination step of determining the coating condition of the object to be inspected by comparing the thermal image adjusted in the position adjustment step with a reference image, which is a thermal image of the object to be inspected on which the coating material has been normally applied .

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