Gap inspection method and gap inspection device

Abstract

In this clearance inspection method, first, a region which includes an ignition coil (3) and a fuel tube (4) is scanned to obtain measurement data including a portion of the outer surface of each of such components, and to obtain design data including the outer shape of each of the components and the positional relationship between the two components within an assembly. Further, in the clearance inspection method: the design data of the ignition coil (3) is aligned, as a rigid body, with the position of the measurement data of the ignition coil (3), and the outer shape of the ignition coil (3) including a hidden outer surface portion is generated; the design data of the fuel tube (4) is aligned, as a non-rigid body, with the position of the design data of the fuel tube (4); the outer shape of the fuel tube (4) including a hidden outer surface portion is generated; and the distance between the two components is calculated.

Description

[Technical Field]

[0001] The present invention relates to a gap inspection method and a gap inspection device for inspecting the distance between a first part and a second part in an assembly formed by assembling a plurality of parts including a first part that is rigid and a second part that is non-rigid. [Background technology]

[0002] For example, during the inspection process for completed automobiles, a worker may use a ruler to measure the distance between two of the multiple parts arranged in the engine compartment. During this inspection process, the ruler may need to be moved to the far end of the engine compartment while avoiding interference with other parts, making the measurement difficult. Furthermore, there is a risk that the distance measurements will vary depending on the worker's level of skill.

[0003] Patent Document 1 also discloses a gap inspection method for measuring the spatial distance between a first rigid part and a second rigid part of an assembly. In this gap inspection method, the distance between the two parts is measured based on three-dimensional data that is design data for the first part and three-dimensional data that is design data for the second part.

[0004] However, an assembly made up of multiple parts does not necessarily contain only rigid parts, and when the assembly contains both rigid and non-rigid parts, there is a need to measure the distance between the rigid and non-rigid parts.

[0005] The present invention has been made in response to such needs, and provides a gap inspection method and a gap inspection device that can calculate the distance between a first rigid part and a second non-rigid part in an assembly by scanning from the outside. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-10342 Summary of the Invention

[0007] The present invention is a gap inspection method for inspecting the distance between a first part and a second part in an assembly formed by assembling multiple parts including a rigid first part and a non-rigid second part, comprising the steps of: scanning an area including the first part and the second part from the outside using a 3D sensor to obtain measurement data including a portion of the outer surface of each part; obtaining design data including the outer shapes of each of the first part and the second part and their positional relationship within the assembly; aligning the design data of the first part as a rigid body with the position of the measurement data of the first part to generate the outer shape of the first part including the hidden outer surface portion; aligning the design data of the second part as a non-rigid body with the position of the design data of the second part to generate the outer shape of the second part including the hidden outer surface portion; and calculating the distance between any point on the first part and any point on the second part.

[0008] According to the invention, the distance between a first rigid part and a second non-rigid part in an assembly can be calculated by scanning from the outside. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is an explanatory diagram showing various components in an engine compartment of the embodiment as viewed from above. [Figure 2] 1 is a schematic diagram of a gap inspection device according to an embodiment of the present invention. [Figure 3] This is point cloud data of the engine room and its internal parts scanned using a 3D laser scanner. [Figure 4] Point cloud data of the engine bay and its internal components showing 40% progress. [Figure 5] FIG. 10 is an explanatory diagram of reliability. [Figure 6] FIG. 10 is an explanatory diagram showing an indication of the displacement amount of the fuel tube on the display. [Figure 7] 1 is a flowchart showing a gap inspection method according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] An embodiment of the present invention will now be described with reference to the drawings. In this embodiment, the present invention is applied to a gap inspection process in which the spatial positions of two parts in an engine compartment are identified and the minimum gap between them is calculated during the inspection process of a completed automobile.

[0011] FIG. 1 is a top view of some of the various components in an automobile engine compartment 1, which is an assembly of one embodiment, showing the area near the engine intake manifold 2. An ignition coil 3, which is part of the engine's ignition system, is located below the intake manifold 2. A fuel tube 4, which supplies fuel to the engine, is located to the side of the intake manifold 2. The fuel tube 4 is made of a metal tube that is oil-resistant and fire-resistant, and has a circular cross section along its radial direction. As shown in FIG. 1, the fuel tube 4 has a straight portion 4a that extends generally linearly along the side of the intake manifold 2 and an inclined portion 4b that slopes from one end of the straight portion 4a toward the ignition coil 3. The fuel tube 4, made of a metal tube, undergoes some deformation during installation and is therefore considered a non-rigid component. On the other hand, the ignition coil 3 is considered a rigid component whose external shape does not change. The minimum spatial distance (minimum gap) between the ignition coil 3 and the fuel tube 4 is regulated by law, and therefore inspection of this minimum gap is required during the finished vehicle inspection process. In many cases, the design minimum distance between the ignition coil 3 and the fuel tube 4 is regulated at a position on the outer surface of at least one of the ignition coil 3 or the fuel tube 4 that is not visible from the outside, and it is generally difficult for an inspector to measure using a ruler. In this embodiment, the gap between these two components is determined by external measurement using a three-dimensional sensor and calculation processing.

[0012] Furthermore, in addition to the intake manifold 2, the ignition coil 3, and the fuel tube 4, multiple other parts are provided in the engine compartment 1. In the completed vehicle inspection process of this embodiment, the distance between the ignition coil 3 and the fuel tube 4 is inspected in an automobile that is assembled from multiple parts including the ignition coil 3, which is a rigid part, and the fuel tube 4, which is a non-rigid part that takes into account deformation of its shape.

[0013] As shown in Figure 2, one embodiment of a gap inspection device used in the finished vehicle inspection process is mainly composed of a three-dimensional sensor, such as a three-dimensional laser scanner 5, a database 6, a control device 7, and one or more displays 8. In the finished vehicle inspection process, a large number of inspections are carried out sequentially in a predetermined order. The gap inspection device of one embodiment is configured as part of the inspection equipment in the finished vehicle inspection process.

[0014] The 3D laser scanner 5 can obtain the 3D coordinates of the surface shape of the measurement target by irradiating the measurement target with a laser and measuring the reflection time. By performing measurements at a high speed of approximately tens of thousands of points per second, high-density point cloud data can be obtained. While various sizes and types of 3D laser scanners are known, one embodiment uses a type that can be held by an operator and used to scan the measurement target. The target area is measured by manually scanning the area including the ignition coil 3, the fuel tube 4, and other components from the outside. Scanning with this 3D laser scanner 5 obtains point cloud data for the entire area including a portion of the outer surface of the ignition coil 3 and the fuel tube 4, as shown in FIG. 3 . Although point cloud data is actually acquired as time-series data for each frame by scanning, point cloud data for the entire area can be acquired by overlaying the data. It is also desirable to perform noise reduction processing on the acquired point cloud data to remove noise caused by dust or other particles that may have been introduced during scanning. The 3D laser scanner may also require markers to serve as references for identifying the shape and position of the target part during scanning.

[0015] Here, "scanning" in the present invention is a concept that includes either or both of the planar scanning function of the 3D sensor (e.g., 3D laser scanner 5) itself and the movement of the 3D sensor by, for example, an operator. In one embodiment, scanning is performed by using a 3D laser scanner 5 with a planar scanning function and further moving this 3D laser scanner 5. Depending on the size and shape of the target area to be measured or the type of 3D sensor, it is also possible, for example, to arrange multiple 3D sensors fixedly at appropriate positions in space and acquire point cloud data of the target area using the scanning function of each 3D sensor.

[0016] The database 6 stores all design data for the automobile to be inspected. Therefore, shape data for the ignition coil 3 and the fuel tube 4, which are the objects of the gap inspection, are stored as design data, along with data indicating their spatial relationship. Furthermore, the database 6 also stores shape data and positional relationship data for other components present within the area. The design data is stored in the database 6 in the form of CAD data constituting a mesh. During the gap inspection, the necessary design data is read from the database 6 to the control device 7. After the design data is read into the control device 7, known hidden surface removal may be performed on areas other than those involved in the gap between the ignition coil 3 and the fuel tube 4 to reduce the data size.

[0017] The control device 7 first aligns the design data of the ignition coil 3 as a rigid body with the position of the measurement data of the ignition coil 3 to generate the outer shape of the ignition coil 3 including the hidden outer surface portion, and then aligns the design data of the fuel tube 4 as a non-rigid body with the position of the measurement data of the fuel tube 4 to perform various processes to generate the outer shape of the fuel tube 4 including the hidden outer surface portion.The control device 7 then calculates the distance between any point on the ignition coil 3 and any point on the fuel tube 4 based on the generated outer shapes of the ignition coil 3 and the fuel tube 4. Each component of the control device 7 will be described in detail later.

[0018] If the minimum distance calculated by the control device 7 is less than a threshold value prescribed by law, the display 8 displays the displacement (movement) amount required for the fuel tube 4 and the location thereof.

[0019] Next, we will explain each component of the control device 7. As shown in Fig. 2, the control device 7 has a first alignment unit 7a, a progress calculation unit 7b, a second alignment unit (rigid alignment unit) 7c, a third alignment unit (non-rigid alignment unit) 7d, a reliability calculation unit 7e, a first interpolation unit 7f, a second interpolation unit 7g, a distance calculation unit 7h, and a displacement calculation unit 7i.

[0020] The first alignment unit 7a roughly aligns the entire target area (the so-called target area in alignment) including the ignition coil 3, the fuel tube 4, and other components in the measurement data acquired by the 3D laser scanner 5 with the entire area (the so-called reference area in alignment) including the ignition coil 3, the fuel tube 4, and other components in the design data stored in the database 6. More specifically, the first alignment unit 7a uses the FPFH algorithm to search for keypoints in the point cloud data of the entire target area and describes the characteristics of these keypoints, such as the normal vectors of the keypoints and the relative angles of the surroundings. Furthermore, the first alignment unit 7a converts the design data of the entire reference area into point cloud data using a well-known conversion method, and then similarly uses the FPFH algorithm to search for keypoints and describe the characteristics of these keypoints, such as the normal vectors of the keypoints and the relative angles of the surroundings. The first alignment unit 7a then compares the normal vectors between the target keypoints and the reference keypoints and their relative angles with the surrounding point clouds to search for a pair of keypoints whose normal vectors and relative angles approximately match, and then roughly aligns the point cloud data of the reference with the point cloud data of the target using the pair of keypoints. During this rough alignment, the non-rigid fuel tube 4 is considered to be a rigid body, and as a result, for example, an average alignment is performed within the length of the fuel tube 4. The rough alignment of the target region by the first alignment unit 7a is performed in parallel with the progress of scanning the target region. The first alignment unit 7a may also perform rough alignment of the target region using a known algorithm other than the FPFH algorithm.

[0021] The progress calculation unit 7b calculates the progress of the scanning required within the target area after the rough alignment by the first alignment unit 7a and before the detailed alignment of the ignition coil 3 and the fuel tube 4 (described later). That is, the progress calculation unit 7b calculates the progress of the scanning from the ratio between the number of points in the point cloud data of the target area based on the reference design data and the number of points that match between the reference and the target through the rough alignment by the first alignment unit 7a. The progress calculation unit 7b further compares the calculated progress with a predetermined progress threshold (e.g., 40% in this embodiment) and determines in real time whether the progress, which gradually increases as the scanning progresses, has exceeded the progress threshold. For example, information on the current progress and whether the progress has exceeded the progress threshold is displayed on the display 8 via an information output unit (not shown). The operator then continues scanning using the 3D laser scanner 5 according to this display. In other words, scanning by the 3D laser scanner 5 (generation of point cloud data), rough alignment, and progress calculation are repeated in real time until a predetermined progress threshold is exceeded. For example, the area surrounded by the dashed line in Figure 4 corresponds to a progress of 40%.

[0022] In addition to the ratio of the number of data points as described above, the degree of progress may also be evaluated based on the number of viewpoints passed by the 3D laser scanner 5, the number of key points used in rough alignment, etc.

[0023] Since the basic shape or configuration of the area to be scanned is known as design data obtained from the database 6, it is possible to estimate the spatial position of the 3D laser scanner 5 and its movement trajectory, including its movement trajectory, based on the point cloud data sequentially obtained from the 3D laser scanner 5. Then, the progress of scanning can be calculated based on how much of the distance scanned by the 3D laser scanner 5 is included in the length of this movement trajectory.

[0024] In addition, for the viewpoint at the position of the 3D laser scanner 5, multiple representative viewpoints are predetermined, and the progress of scanning can be determined based on how many representative viewpoints the 3D laser scanner 5 passes through before drawing a movement trajectory.

[0025] Furthermore, the maximum number of key points is determined based on the point cloud data converted from the design data, so the progress of scanning can be calculated by finding the ratio of key points based on the point cloud data converted from the measurement data to this maximum number of key points.

[0026] The second alignment unit 7c performs detailed spatial alignment for each component, provided that the progress rate exceeds 40%. Specifically, the second alignment unit 7c searches for paired points in the reference point cloud data for every point in the target point cloud data obtained by measuring the ignition coil 3 and the fuel tube 4, and performs detailed alignment of the reference point cloud data with the target point cloud data. The non-rigid fuel tube 4 is considered to be a rigid body here, and as a result, average alignment is performed within the length of the fuel tube 4. The detailed alignment in the second alignment unit 7c can be performed using an appropriate known algorithm.

[0027] After the detailed alignment by the second alignment unit 7c, the third alignment unit 7d performs so-called non-rigid alignment of non-rigid components (fuel tube 4 in this embodiment) taking deformation into account. Any known algorithm can be used here. For example, the third alignment unit 7d searches for nearest neighbor pairs from the reference point cloud data and target point cloud data, which have been previously aligned as rigid bodies, and calculates rotation, scaling, and translation parameters to bring the paired points closer to each other. For example, the outer shape of the fuel tube 4 is downsampled to form an outer surface composed of multiple triangles with vertices and edges. Using the vertices representing the point clouds (clusters) of each downsampled region, i.e., each region containing multiple adjacent triangles, the deformation of the cluster is decomposed into rotation, scaling, and translation parameters under the constraint that the edge length does not change (strictly speaking, the length change is minimized). The deformation of the entire fuel tube 4 is obtained as a collection of such cluster-based deformations. The third alignment unit 7d aligns the reference point cloud data for the fuel tube 4 with the target point cloud data in space while deforming the reference point cloud data for the fuel tube 4 using a non-rigid alignment method that takes such deformation into consideration.

[0028] The reliability calculation unit 7e calculates the reliability of the alignment of each target component (i.e., the ignition coil 3 and the fuel tube 4). In other words, the reliability calculation unit 7e calculates the reliability indicating how close the target point cloud data is to the aligned reference point cloud data for each of the ignition coil 3 and the fuel tube 4.

[0029] FIG. 5 is an explanatory diagram that schematically shows point cloud data of a fuel tube 4 after alignment to explain reliability. For simplicity, it is assumed here that the circular outer surface of a cross section of the fuel tube 4 is formed by 13 pieces of point cloud data. The 13 pieces of point cloud data Dr arranged in a circle are reference point cloud data based on design data, and the seven pieces of point cloud data Dt arranged in a semicircle are target point cloud data based on measurement data. For example, if scanning by the 3D laser scanner 5 is performed only from the top of the figure, the lower half will be an area that was not scanned (a missing area), and the target point cloud data Dt will be arranged in a semicircle.

[0030] The reliability is expressed, for example, as the ratio between the number of points in the reference point cloud data Dr and the number of points in the target point cloud data Dt that fall within a radius L from each point in the reference point cloud data Dr. In the figure, the range of radius L from the numerous points in the reference point cloud data Dr is represented by an outer circle C1 and an inner circle C2, each indicated by a dashed line. In the example shown in FIG. 5( a), four target point cloud data Dt are included within the range R of the circles C1 and C2, resulting in a reliability of 4 / 13. In the example shown in FIG. 5( b), two target point cloud data Dt are included within the range R of the circles C1 and C2, resulting in a reliability of 2 / 13. In the example shown in FIG. 5( c), all of the target points, i.e., seven point cloud data Dt, are included within the region R, resulting in a reliability of 7 / 13. Thus, the reliability is affected by both the accuracy of alignment and the size or proportion of missing areas in the measurement data.

[0031] The first interpolation unit 7f uses reference point cloud data to interpolate missing portions that have not been scanned in the measurement data of the ignition coil 3, i.e., the target point cloud data. In other words, the first interpolation unit 7f interpolates the outer surface portion of the back (lower) side of the ignition coil 3, which is hidden from view from above the engine compartment 1, using the reference point cloud data to generate point cloud data including the hidden portion. The first interpolation unit 7f then converts the generated point cloud data into mesh data that constitutes a surface using a well-known conversion method.

[0032] Similarly, the second interpolation unit 7g interpolates missing portions that have not been scanned in the measurement data of the fuel tube 4, i.e., the target point cloud data, using the reference point cloud data. In other words, the outer surface portion of the back side (lower side) of the fuel tube 4, which is hidden from view from above the engine compartment 1, is interpolated using the reference point cloud data to generate point cloud data of the fuel tube 4 including the hidden portion. Then, the second interpolation unit 7g converts the generated point cloud data into mesh data that constitutes a surface using a well-known conversion method.

[0033] The distance calculation unit 7h calculates the distance from each point on the surface of the ignition coil 3 to each point on the surface of the fuel tube 4 based on the mesh data of the ignition coil 3 acquired by the first interpolation unit 7f and the mesh data of the fuel tube 4 acquired by the second interpolation unit 7g. Furthermore, the distance calculation unit 7h obtains the minimum distance by comparing the calculated distances with each other. The distance calculation unit 7h may calculate the distance from each point on the ignition coil 3 to each point on the fuel tube 4 based on the point cloud data of the ignition coil 3 and the point cloud data of the fuel tube 4 without converting them into mesh data. The distance calculation unit 7h also compares the minimum distance with a predetermined threshold, and if the minimum distance is less than the threshold, displays information on the display 8 that the minimum distance is less than the threshold. When presenting information to a worker that the minimum distance is less than the threshold, in addition to the above-mentioned image presentation using the display, the information may be presented by sound using an audio device such as a speaker, or by vibration using a wearable device such as a scanner held by the worker or a watch worn by the worker. In the case of presenting information by vibration, whether the minimum distance is above or below the threshold may be presented using a predetermined vibration pattern.

[0034] When the minimum distance is less than a predetermined threshold, the displacement amount calculation unit 7i quantitatively calculates the amount of movement required for the fuel tube 4 at the point where the minimum distance is reached and for several representative points, that is, the amount of displacement of the fuel tube 4 required for the minimum distance to be equal to or greater than the threshold, and presents the information on the display 8.

[0035] The display 8 displays the minimum distance and location between the ignition coil 3 and the fuel tube 4, along with the displacement amount required for the fuel tube 4. The display 8 also shows the desired placement of the fuel tube 4 in the engine compartment 1 by the area between two curves W1 and W2 shown by dashed lines in Fig. 6, and if the minimum distance is less than the threshold, the worker displaces the fuel tube 4 based on the displacement amount (not shown) displayed on the display 8, thereby placing the fuel tube 4 in the area between the curves W1 and W2. The dark-colored portion adjacent to the side of the fuel tube 4 indicates a portion of the fuel tube 4 before the worker displaces it. 6, the displacement amount calculation unit 7i displays a displacement of 20 mm in a direction P away from the intake manifold 2 for a point on the straight portion 4a that extends linearly along the side of the intake manifold 2, and further displays a displacement of 10 mm in another direction Q away from the intake manifold 2 for a point on the inclined portion 4b that is inclined toward the ignition coil 3 (see FIG. 1). Note that while the minimum distance and the location of the minimum distance are not shown in FIG. 6, the location of the minimum distance is located between the ignition coil 3 (see FIG. 1) and a point on the inclined portion 4b that is diagonally downward and to the left of the point where the displacement amount in direction Q is applied.

[0036] Next, the gap inspection method of this embodiment will be described with reference to the flowchart of FIG.

[0037] First, in step S1, an operator operates the 3D laser scanner 5 to scan a predetermined area in the engine compartment 1 from the outside, including the target components, the ignition coil 3 and the fuel tube 4, to obtain point cloud data including a portion of the outer surface of each component. This scanning and generation of point cloud data progresses gradually as the scanning operation proceeds.

[0038] Next, in step S2, CAD data of the target components, ignition coil 3 and fuel tube 4, and other peripheral components are obtained from database 6, along with CAD data indicating their spatial positional relationships.

[0039] Then, in step S3, the CAD data is converted into point cloud data using a known appropriate conversion method.

[0040] Next, in step S4, the first alignment unit 7a performs rough alignment between the entire target area and the entire reference area. As described above, rough alignment is performed by aligning the point cloud data of the entire area including the ignition coil 3, the fuel tube 4, and other components with the point cloud data of the entire area including the ignition coil, the fuel tube, and other components in the design data stored in the database 6 by searching for key points and combining paired key points.

[0041] After the rough alignment in step S4, in step S5, the progress calculation unit 7b calculates the progress of scanning from the ratio between the number of points in the point cloud data of the reference area and the number of matching points in the point cloud data of the scanned area.

[0042] Then, in step S6, it is determined whether this progress rate exceeds a predetermined progress rate threshold (40% in this embodiment, but the threshold is not limited to this). If the progress rate is 40% or less, the process proceeds to step S7, where the progress rate is displayed on the display 8 and the worker continues scanning. In other words, the process from step S1 onwards is repeated.

[0043] Furthermore, if the progress rate exceeds 40% in step S6, the process proceeds to step S8, where the target components, the ignition coil 3 and the fuel tube 4, are extracted from the point cloud data of the measurement data and the point cloud data of the design data, respectively. The point cloud data extracted from the measurement data becomes the so-called target, and the point cloud data extracted from the design data becomes the so-called reference. The point cloud data of the target components that serve as the reference may be generated from CAD data of the individual components.

[0044] Next, in step S9, the second alignment unit 7c uses a known appropriate algorithm to perform detailed alignment of the ignition coil 3 and the fuel tube 4. Here, the fuel tube 4 is considered to be a rigid body. For example, as described above, paired points are searched for between the point cloud data of the target that has undergone rough alignment and the point cloud data of the reference, and detailed alignment is performed so that the reference approaches the target.

[0045] Next, in step S10, the third alignment unit 7d described above downsamples the data of the fuel tube 4 in order to perform non-rigid alignment of the fuel tube 4, which is a non-rigid body. Then, in step S11, non-rigid alignment is performed taking into account the deformation of the fuel tube 4. That is, the reference point cloud data is aligned with the target position while being deformed. In this non-rigid alignment, the nearest pair is searched for from the reference point cloud data and target point cloud data, which have been aligned assuming a rigid body as described above, and rotation, enlargement, and translation are calculated as parameters for bringing them closer to each other.

[0046] Next, the process proceeds to step S12, where the reliability of the alignment is calculated for each of the ignition coil 3 and the fuel tube 4. The reliability is expressed, for example, as the ratio between the number of points in the reference point cloud data and the number of points in the target point cloud data that are included within a predetermined radius from each point in the reference point cloud data.

[0047] Then, in step S13, it is determined whether or not the reliability of the ignition coil 3 and the reliability of the fuel tube 4 each satisfy a predetermined reliability. If both reliability levels satisfy the predetermined reliability, it is determined that alignment is complete and the process proceeds to step S14.

[0048] In step S14, the first interpolation unit 7f and the second interpolation unit 7g interpolate unscanned portions of the target point cloud data of the ignition coil 3 and the fuel tube 4 with reference point cloud data aligned with the targets. As a result, point cloud data of the ignition coil 3 and the fuel tube 4 including unscanned portions (i.e., hidden portions) is generated at the positions of each target.

[0049] Then, in step S15, a known conversion method is used to convert the point cloud data including the unscanned portions of both the ignition coil 3 and the fuel tube 4 into mesh data that constitutes a surface.

[0050] Next, in step S16, distance calculation unit 7h calculates the minimum distance between ignition coil 3 and fuel tube 4 based on the mesh data of ignition coil 3 and the mesh data of fuel tube 4. That is, the distance between any two points on each surface is found, and the minimum value among these is set as the minimum distance.

[0051] Then, in step S17, it is determined whether the minimum distance is equal to or greater than the threshold value. If the minimum distance is equal to or greater than the threshold value, the process proceeds to step S18, where information that the minimum distance is equal to or greater than the threshold value is presented on the display 8.

[0052] If the minimum threshold is less than the threshold in step S17, the process proceeds to step S19, where the displacement amount calculation unit 7i calculates the displacement amount of the fuel tube 4 required to make the minimum distance equal to or greater than the threshold. The calculated displacement amount is displayed on the display 8.

[0053] If the reliability is less than the predetermined reliability in step S13, the process proceeds to step S20, where it is determined whether the scanned data is insufficient. If the data is insufficient, the process proceeds to step S21, where the operator is informed that scanning needs to be performed again using the 3D laser scanner 5, and the process returns to step S1.

[0054] If it is determined in step S20 that there is sufficient data, it is assumed that the reliability in step S13 was determined to be low due to excessive deformation of the fuel tube 4, and the process proceeds to step S18, where a message to that effect is displayed on the display 8.

[0055] As described above, in this embodiment, the first interpolator 7f uses the reference point cloud data to interpolate the outer surface portion hidden behind the rigid ignition coil 3 after alignment, thereby generating point cloud data including the hidden portion and acquiring the outer shape. Similarly, the second interpolator 7g uses the reference point cloud data to interpolate the outer surface portion hidden behind the non-rigid fuel tube 4 after alignment, thereby generating point cloud data including the hidden portion and acquiring the outer shape. The outer surface shape of the non-rigid fuel tube 4, which takes deformation into consideration, is difficult to grasp, and interpolation is difficult by simply applying design data. However, as in this embodiment, by performing alignment and generating point cloud data including the hidden portion of the fuel tube 4 to acquire the outer shape, and using this data together with the outer shape of the ignition coil 3, the distance between any point on the ignition coil 3 and any point on the fuel tube 4 can be easily calculated.

[0056] In this embodiment, the distance calculation unit 7h calculates the minimum distance between the ignition coil 3 and the fuel tube 4. The distance calculation unit 7h then compares the minimum distance with a threshold value, and when the minimum distance is less than the threshold value, displays information on the display 8 indicating that the minimum distance is less than the threshold value. Furthermore, when the minimum distance is less than the threshold value, the displacement calculation unit 7i quantitatively calculates the location of the minimum distance and the displacement amount of the fuel tube 4 required to make the minimum distance equal to or greater than the threshold value, and displays the information on the display 8. This allows the worker to accurately displace the fuel tube 4 toward the desired position while looking at the fuel tube 4 displayed on the display 8 when the minimum distance is less than the threshold value. Furthermore, since the information that the minimum distance is less than the threshold value is displayed by sound or vibration, the worker can recognize that the minimum distance is less than the threshold value while continuing his or her work without averting his or her eyes.

[0057] In this embodiment, point cloud data generated from design data of an area including the ignition coil 3 and the fuel tube 4 is roughly aligned using key points with point cloud data of the area acquired by scanning as measurement data. Then, the point cloud data of the ignition coil 3 based on the design data is aligned with the point cloud data of the ignition coil 3 extracted from the measurement data. Furthermore, the point cloud data of the fuel tube 4 based on the design data is aligned with the point cloud data of the fuel tube 4 extracted as a non-rigid body from the measurement data. In other words, the positional relationship between the ignition coil 3 and the fuel tube 4 is acquired in the scanned area during rough alignment, and then detailed alignment is performed for each of them. Therefore, the distance, i.e., the gap, can be calculated accurately based on the positional relationship between the ignition coil 3 and the fuel tube 4.

[0058] Furthermore, in this embodiment, the minimum distance between the ignition coil 3 and the fuel tube 4 is inspected during the finished vehicle inspection process. During the finished vehicle inspection, the ignition coil 3 and the fuel tube 4 are already assembled together with various components such as the intake manifold 2, and the ignition coil 3 is located further back than the intake manifold 2 when viewed from above the engine compartment 1, making it difficult to measure. Furthermore, the fuel tube 4 is a non-rigid body that undergoes deformation, making it more difficult to measure than a rigid body. Therefore, by using the gap inspection method of this embodiment to efficiently inspect the minimum distance between the ignition coil 3 and the fuel tube 4 during the finished vehicle inspection process, which includes the ignition coil 3 and the fuel tube 4, which are difficult to measure, the time required for the finished vehicle inspection process can be shortened compared to when an operator performs inspection using, for example, a ruler.

[0059] Furthermore, in this embodiment, the design minimum distance between the ignition coil 3 and the fuel tube 4 may be defined by the position of an outer surface that is not visible from the outside of at least one of the ignition coil 3 or the fuel tube 4. Even in cases where such an outer surface that is not visible from the outside of the ignition coil 3 or the fuel tube 4 is included, the minimum distance between the ignition coil 3 and the fuel tube 4 can be calculated by interpolating the above-mentioned outer surface that is not visible using the first interpolation unit 7f and the second interpolation unit 7g of the gap inspection device of this embodiment.

[0060] In this embodiment, an example of calculating the distance between the rigid ignition coil 3 and the non-rigid fuel tube 4 is disclosed, but the distance between other rigid parts and non-rigid parts arranged in the engine room 1 may also be calculated.

[0061] Furthermore, in this embodiment, an example of non-rigid alignment of a fuel tube 4 having a circular radial cross section has been described, but the present invention may also be applied to non-rigid alignment of a pipe having a radial cross section other than a circular one, for example, a rectangular one.

[0062] Furthermore, in this embodiment, an example of calculating the distance between a rigid part and a non-rigid part of an automobile is disclosed, but the distance between a rigid part and a non-rigid part used in an object other than an automobile may also be calculated.

[0063] Furthermore, in the above embodiment, an example has been described in which the three-dimensional laser scanner 5 is held and operated by an operator, but the present invention can also be applied to cases in which scanning is performed by a robot using a three-dimensional sensor.

[0064] In addition, in this embodiment, a 3D laser scanner 5 has been described as a 3D sensor, but other types of 3D sensors, such as ToF types and triangulation types such as stereo cameras, can be widely applied.

Claims

1. 1. A gap inspection method for inspecting a distance between a first part that is rigid and a second part that is non-rigid in an assembly formed by assembling a plurality of parts, the first part and the second part, the method comprising: scanning an area including the first part and the second part from the outside with a three-dimensional sensor to obtain measurement data including a portion of the outer surface of each part; acquiring design data including the external shapes of the first part and the second part and the positional relationship between the two parts within the assembly; aligning the design data of the first part as a rigid body with the position of the measurement data of the first part, and when the reliability of the alignment of the first part is satisfied, interpolating the hidden outer surface portion based on the design data of the first part, and generating an outer shape of the first part including the hidden outer surface portion; aligning design data of the second part as a non-rigid body with the position of measurement data of the second part, and when the reliability of the alignment of the second part is satisfied, interpolating a hidden outer surface portion based on the design data of the second part, and generating an outer shape of the second part including the hidden outer surface portion; Calculating the distance between any point on the first part and any point on the second part; Gap inspection method.

2. The gap inspection method according to claim 1 , further comprising calculating a minimum distance between the first component and the second component.

3. The gap inspection method according to claim 2 , further comprising: comparing the minimum distance with a threshold; and, when the minimum distance is less than the threshold, presenting information that the minimum distance is less than the threshold.

4. The gap inspection method according to claim 3, further comprising: when the minimum distance is less than the threshold value, calculating the location of the minimum distance and the amount of displacement of the second component required to make the minimum distance equal to or greater than the threshold value, and presenting the information.

5. The gap inspection method according to claim 3 , further comprising presenting the information that the gap is less than the threshold value by using at least one of an image, a sound, and a vibration.

6. After roughly aligning point cloud data generated from design data of an area including the first part and the second part with point cloud data of an area acquired by scanning as measurement data using key points, 2. The gap inspection method according to claim 1, wherein point cloud data of the first part based on design data is aligned with point cloud data of the first part extracted from measurement data, and point cloud data of the second part based on design data is aligned with point cloud data of the second part extracted from measurement data as a non-rigid body.

7. 2. The gap inspection method according to claim 1, wherein the assembly is an automobile, the second part is a pipe arranged in an engine compartment, and the first part is a part in the engine compartment for which a minimum distance between the first part and the pipe is specified.

8. 2. The gap inspection method according to claim 1, wherein the minimum distance between the first part and the second part is inspected during inspection of a completed automobile.

9. 2. The gap inspection method according to claim 1, wherein the design minimum distance between the first part and the second part is defined at a position on an outer surface of at least one of the first part or the second part that is not visible from the outside.

10. 1. A gap inspection device for inspecting a distance between a first part that is rigid and a second part that is non-rigid in an assembly formed by assembling a plurality of parts, the first part and the second part, a three-dimensional sensor that scans an area including the first part and the second part from the outside to acquire measurement data including a portion of the outer surface of each part; a database that stores design data including the external shapes of the first part and the second part and the positional relationship between the two parts within the assembly; a rigid body alignment unit that aligns the design data of the first part with a position of the measurement data of the first part as a rigid body; a non-rigid body alignment unit that aligns design data of the second part with a position of measurement data of the second part as a non-rigid body; a reliability calculation unit that calculates a reliability of alignment for each of the first part and the second part; a first interpolation unit that, when the reliability of the alignment of the first part is satisfied, interpolates a hidden outer surface portion of the first part based on design data of the first part, and generates an outer shape of the first part including the hidden outer surface portion; a second interpolation unit that, when the reliability of the alignment of the second part is satisfied, interpolates a hidden outer surface portion of the second part based on design data of the second part, and generates an outer shape of the second part including the hidden outer surface portion; a distance calculation unit that calculates a distance between an arbitrary point on the first part and an arbitrary point on the second part; A gap inspection device equipped with

11. 1. A gap inspection method for inspecting a distance between a first part that is rigid and a second part that is non-rigid in an assembly formed by assembling a plurality of parts, the first part and the second part, the method comprising: scanning an area including the first part and the second part from the outside with a three-dimensional sensor to obtain measurement data including a portion of the outer surface of each part; acquiring design data including the external shapes of the first part and the second part and the positional relationship between the two parts within the assembly; After aligning the design data of the first part as a rigid body to the position of the measurement data of the first part, aligning the design data of the second part as a non-rigid body to the position of the measurement data of the second part; generating an outer shape including hidden outer surface portions of the first part and the second part; Calculating the distance between any point on the first part and any point on the second part; Gap inspection method.

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