Workpiece quality determination method and workpiece quality determination system

Abstract

The present invention is to solve the problem that the deformation of the workpiece surface can be automatically determined without the reference shape data of the workpiece. In order to solve the above problem, a workpiece quality determination system determines the quality of a workpiece based on a fringe pattern projected onto the workpiece surface, and includes: an observation angle setting section that sets an observation angle for observing a projected fringe pattern projected onto the workpiece; a fringe projection angle setting section that sets a fringe projection angle of the projected fringe pattern at the set observation angle; a reference fringe creating section that creates a reference fringe pattern based on the projected fringe pattern at the set fringe projection angle; and a quality determination section that calculates a difference between the projected fringe pattern and the reference fringe pattern at the fringe projection angle, and performs quality determination based on the difference.

Description

Technical Field

[0001] This invention relates to a method and system for judging the quality of workpieces. Background Technology

[0002] Industrial products such as automobile bodies are formed by stamping or welding steel sheets. These processes are performed according to predetermined settings. However, the shape of the formed industrial product varies slightly depending on the thickness and composition of the steel sheet. Therefore, the shape of the formed industrial product is observed to determine whether deformations such as dents have occurred (quality assessment).

[0003] Previously, such quality assessments were made by an observer visually confirming the stripe pattern projected onto the workpiece surface (hereinafter sometimes referred to as the "projected stripe pattern"). However, since assessments based on visual confirmation rely on the observer's experience, there is a problem that different observers may produce different results.

[0004] Therefore, a method for automating the quality assessment of workpiece surfaces has been proposed previously. For example, Patent Document 1 describes a method that uses reference shape data, which serves as three-dimensional shape data in the workpiece's appearance design, to project a stripe pattern onto the reference shape to generate a reference stripe pattern. This reference stripe pattern is then slid relative to a projected stripe pattern projected onto the workpiece surface. The difference between the reference stripe pattern and the projected stripe pattern is calculated, and the quality is automatically assessed based on this difference. This allows for the automatic detection of deformations on the workpiece surface without relying on the observer's experience.

[0005] [Previous Technical Documents]

[0006] (Patent Documents)

[0007] Patent Document 1: Japanese Patent Application Publication No. 2014-224803 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] However, in the method described in Patent Document 1, in order to generate the reference stripe pattern, reference shape data, which is the three-dimensional shape data of the workpiece's appearance design, is required. However, in reality, it is difficult to form a workpiece whose three-dimensional reference shape data is completely consistent with the shape of the formed industrial product, and there is a problem that the result of comparing with the reference shape data cannot be correlated with the actual deformation.

[0010] The purpose of this invention is to provide a workpiece quality judgment method and a workpiece quality judgment system that can automatically determine whether the workpiece surface has been deformed without requiring reference shape data of the workpiece.

[0011] [Technical means to solve the problem]

[0012] (1) The workpiece quality judgment method disclosed herein judges the quality of a workpiece based on a stripe pattern projected onto the surface of a workpiece (e.g., workpiece W described later). The workpiece quality judgment method is characterized by including: an observation angle setting process (e.g., a process performed by the observation angle setting unit 12 described later), setting the angle for observing the projected stripe pattern (e.g., projected stripe pattern 300 described later) projected onto the aforementioned workpiece; a stripe projection angle setting process (e.g., a process performed by the stripe projection angle setting unit 13 described later), setting the stripe projection angle of the aforementioned projected stripe pattern at the set observation angle; a reference stripe pattern making process (e.g., a process performed by the reference stripe making unit 14 described later), making a reference stripe pattern (e.g., reference stripe pattern 301 described later) based on the projected stripe pattern at the set stripe projection angle; and a quality judgment process (e.g., a process performed by the quality judgment unit 15 described later), calculating the difference between the projected stripe pattern and the reference stripe pattern at the aforementioned stripe projection angle, and performing a quality judgment based on the aforementioned difference.

[0013] (2) In the workpiece quality judgment method described in (1) above, preferably, the aforementioned stripe projection angle uses the longer direction of the workpiece curvature as the projection reference angle, and the aforementioned quality judgment process changes the aforementioned stripe projection angle from the aforementioned projection reference angle to multiple angles to perform the aforementioned quality judgment.

[0014] (3) In the workpiece quality judgment method described in (1) or (2) above, it is preferred that the aforementioned difference is the angle and amplitude formed by the aforementioned projected stripe pattern and the aforementioned reference stripe pattern.

[0015] (4) The workpiece quality judgment system of this disclosure (e.g., the workpiece quality judgment system 1 described later) judges the quality of a workpiece based on a stripe pattern projected onto the surface of a workpiece (e.g., workpiece W described later). The workpiece quality judgment system includes: an observation angle setting unit (e.g., observation angle setting unit 12 described later) that sets an observation angle for observing the projected stripe pattern (e.g., projected stripe pattern 300 described later) projected onto the workpiece; a stripe projection angle setting unit (e.g., stripe projection angle setting unit 13 described later) that sets the stripe projection angle of the projected stripe pattern at the set observation angle; a reference stripe production unit (e.g., reference stripe production unit 14 described later) that produces a reference stripe pattern (e.g., reference stripe pattern 301 described later) based on the projected stripe pattern at the set stripe projection angle; and a quality judgment unit (e.g., quality judgment unit 15 described later) that calculates the difference between the projected stripe pattern and the reference stripe pattern at the stripe projection angle and judges the quality based on the difference.

[0016] (5) In the workpiece quality judgment system described in (4) above, preferably, the stripe projection angle is the projection reference angle of the longer curvature direction of the workpiece, and the quality judgment unit changes the stripe projection angle from the projection reference angle to multiple angles to perform the aforementioned quality judgment.

[0017] (6) In the workpiece quality judgment system described in (4) or (5) above, preferably, the aforementioned difference is the angle and amplitude formed by the aforementioned projected stripe pattern and the aforementioned reference stripe pattern.

[0018] (The effect of the invention)

[0019] According to the workpiece quality judgment method described in (1) above, since a reference stripe pattern is created based on the projected stripe pattern projected onto the workpiece, it is not necessary to have reference shape data for the workpiece to automatically determine whether the workpiece surface has been deformed. Since the reference stripe pattern is generated based on the projected stripe pattern, an evaluation based on the appearance of the actual object can be performed. Since the stripe projection angle of the projected stripe pattern projected onto the workpiece is set at the observation angle and at each observation angle, a quantitative evaluation of the workpiece surface can be performed using various angles, and a high-precision quality judgment with no deviation in the evaluation results can be performed.

[0020] According to the workpiece quality judgment method described in (2) above, since the longer curvature direction of the workpiece is used as the reference to set the stripe projection angle, stable results can be obtained, especially when the object being judged is a narrow curved surface. Thus, a quality judgment method with high versatility can be provided.

[0021] According to the workpiece quality judgment method described in (3) above, the difference is calculated by determining the angle and amplitude between the projected fringe pattern and the reference fringe pattern, thus eliminating the need for processes such as sliding the reference fringe pattern relative to the projected fringe pattern. Therefore, a simpler and faster quality judgment can be performed.

[0022] According to the workpiece quality judgment system described in (4) above, since a reference stripe pattern is created based on the projected stripe pattern projected onto the workpiece, it is not necessary to have reference shape data for the workpiece to automatically determine whether the workpiece surface has been deformed. Since the reference stripe pattern is generated based on the projected stripe pattern, an evaluation based on the appearance of the actual object can be performed. Since the stripe projection angle of the projected stripe pattern projected onto the workpiece is set at the observation angle and at each observation angle, a quantitative evaluation of the workpiece surface can be performed using various angles, and a high-precision quality judgment with no deviation in the evaluation results can be performed.

[0023] According to the workpiece quality assessment system described in (5) above, since the longer curvature direction of the workpiece is used as the reference for setting the stripe projection angle, stable results can be obtained, especially when the assessment object is a narrow curved surface. Thus, a highly versatile quality assessment system can be provided.

[0024] According to the workpiece quality judgment system described in (6) above, the difference is calculated by determining the angle and amplitude between the projected fringe pattern and the reference fringe pattern, thus eliminating the need for complicated procedures such as sliding the reference fringe pattern relative to the projected fringe pattern. Therefore, a simpler and faster quality judgment can be performed. Attached Figure Description

[0025] Figure 1 This is a block diagram illustrating the functional structure of the workpiece quality assessment system.

[0026] Figure 2A This is a diagram illustrating an example of the structure of a workpiece quality assessment system.

[0027] Figure 2B This is another example of a diagram illustrating the structure of a workpiece quality assessment system.

[0028] Figure 3 This is a flowchart illustrating an example of the processing flow of a workpiece quality assessment system.

[0029] Figure 4 It is a three-dimensional drawing showing a part of the workpiece that is the object of quality assessment.

[0030] Figure 5 This is the main view of the judgment object surface, which explains the method for setting the viewing angle relative to the judgment object surface.

[0031] Figure 6 This is a top view of the judgment object plane, illustrating the method for setting the observation angle relative to the judgment object plane.

[0032] Figure 7 It is a diagram that shows the pattern of projected stripes onto a workpiece.

[0033] Figure 8 It is a diagram illustrating the longer and shorter curvature directions of a workpiece.

[0034] Figure 9 It is a diagram illustrating the projection angle of the projected stripe pattern onto the workpiece.

[0035] Figure 10 This diagram illustrates a method for creating a reference stripe pattern based on a projected stripe pattern onto a workpiece.

[0036] Figure 11A This is a schematic diagram illustrating the method for calculating the angle and amplitude between the reference fringe pattern and the projected fringe pattern.

[0037] Figure 11B This is a schematic diagram illustrating the method for calculating the angle and amplitude between the reference fringe pattern and the projected fringe pattern.

[0038] Figure 12 This diagram illustrates the method for calculating the angle and amplitude between the reference fringe pattern and the projected fringe pattern. Detailed Implementation

[0039] Reference Figure 1-Figure 2 1. This paper describes the workpiece quality assessment method and the workpiece quality assessment system using this method. First, refer to... Figure 1 The functions of the workpiece quality judgment system 1 disclosed herein will be explained. Figure 1 This is a block diagram illustrating the functional structure of the workpiece quality judgment system 1.

[0040] [Functions of Workpiece Quality Judgment System 1]

[0041] The workpiece quality judgment system 1 is configured to include a stripe projection unit 11, an observation angle setting unit 12, a stripe projection angle setting unit 13, a reference stripe production unit 14, a quality judgment unit 15, and a storage unit 16.

[0042] The stripe projection unit 11 projects a stripe pattern for quality judgment onto the surface of the workpiece W. Specifically, the stripe projection unit 11 determines the judgment target surface on the surface of the workpiece W for quality judgment and projects a stripe pattern onto the judgment target surface.

[0043] The observation angle setting unit 12 sets the angle (hereinafter referred to as "observation angle") for observing the projected stripe pattern, which is projected onto the surface of the workpiece W. The observation angle of the projected stripe pattern is set to multiple angles with different fields of view in the front-back and up-down directions, which will be described in detail later.

[0044] The stripe projection angle setting unit 13 sets the projection angle of the stripe pattern projected onto the surface of the workpiece W. The projection angle setting includes multiple projection angles, each with a different angle formed by the extension direction of the line segments constituting the projected stripe pattern relative to the projection reference angle. These will be described in detail later.

[0045] The reference fringe fabrication unit 14 smooths the projected fringe pattern projected onto the judgment surface of the workpiece W, and fabricates a reference fringe pattern based on the projected fringe pattern. When deformation (concavity and convexity) occurs on the surface of the workpiece W, this deformation manifests as creases in the projected fringe pattern. The reference fringe fabrication unit 14 smooths each line segment of the projected fringe pattern projected onto the judgment surface of the workpiece W, thereby creating a reference fringe pattern with no or few creases relative to the projected fringe pattern. Smoothing is achieved by thinning out multiple control points on the line segments constituting the projected fringe pattern, thereby forming a smooth curve from those line segments. This smoothing process is known, and existing methods such as NURBS (Non-Uniform Rational B-Spiine) can be used, for example.

[0046] The quality judgment unit 15 compares the projected stripe pattern with the reference stripe pattern at each observation angle set by the observation angle setting unit 12 and each projection angle set by the stripe projection angle setting unit 13 to calculate the difference, and performs a quality judgment on whether the object surface of the workpiece W is deformed based on the calculated difference.

[0047] The storage unit 16 stores the three-dimensional shape data of the workpiece W and the data generated in each process.

[0048] [Structure of Workpiece Quality Judgment System 1]

[0049] Next, referring to FIG2, the specific structure of the workpiece quality assessment system 1 will be described. The workpiece quality assessment system 1 is configured to include at least a computer 102 capable of performing three-dimensional image processing.

[0050] Figure 2A The image shows an example of a workpiece quality assessment system 1. For example... Figure 2AAs shown, the workpiece quality assessment system 1 is configured to include a three-dimensional scanner 101 capable of measuring the surface shape of workpiece W and a computer 102. In this embodiment, the workpiece quality assessment system 1 represents a case where a car body is used as the quality assessment object, i.e., workpiece W. However, the quality assessment object, i.e., workpiece W, is not limited to a car body; it can be any industrial product whose surface quality needs to be assessed after molding.

[0051] A 3D scanner 101 measures the surface shape of a workpiece W and provides the resulting 3D shape data to a computer 102. The computer 102 is equipped with a predefined program capable of 3D image processing, such as projecting a stripe pattern onto the measured surface shape of the workpiece W, changing the viewing angle of the projected stripe pattern, and changing the projection angle. Using the 3D shape data provided by the 3D scanner 101, the computer 102 performs 3D image processing to execute the workpiece quality assessment method described later, thereby assessing the quality of the workpiece W.

[0052] Figure 2B Another example of a workpiece quality assessment system 1 is illustrated in the diagram. For example... Figure 2B As shown, the workpiece quality judgment system 1 is configured to include a stripe projection device 103 that projects a stripe pattern onto the surface of the workpiece W, a camera 104 that captures the stripe pattern (projected stripe pattern) projected onto the workpiece W, and a computer 102.

[0053] The stripe projection device 103 is a wall surface that forms a stripe pattern and is disposed around the workpiece W. When light is shone from the stripe projection device 103 toward the workpiece W, the stripe pattern formed on the stripe projection device 103 is projected onto the surface of the workpiece W. At this time, the stripe projection device 103 can set the projection angle of the projected stripe pattern relative to the surface of the workpiece W to multiple different angles. The camera 104 captures images of the projected stripe pattern projected onto the surface of the workpiece W and provides the captured image data of the projected stripe pattern to the computer 102. At this time, the camera 104 captures images of the workpiece W from various angles by changing the field of view, thereby setting the viewing angle of the projected stripe pattern to multiple different angles. The computer 102 uses the image data (projected stripe pattern) provided by the camera 104 to perform three-dimensional image processing to execute the workpiece quality judgment method described later, thereby judging the quality of the workpiece W.

[0054] Alternatively, the stripe projection device 103 can be a single wall without a light source. If a stripe pattern is formed on the wall surrounding the workpiece W, the stripe pattern will be projected onto the surface of the workpiece W even if no light is irradiated onto the workpiece W from the stripe projection device 103.

[0055] exist Figure 2AIn the workpiece quality judgment system 1 with the structure shown, the processor and memory of the computer 102 perform the functions of the stripe projection unit 11, the observation angle setting unit 12, the stripe projection angle setting unit 13, the reference stripe production unit 14, the quality judgment unit 15, and the storage unit 16. Figure 2B In the workpiece quality judgment system 1 with the structure shown, the stripe projection device 103 functions as the stripe projection unit 11 and the stripe projection angle setting unit 13, the camera 104 functions as the observation angle setting unit 12, and the processor and memory of the computer 102 function as the reference stripe production unit 14, the quality judgment unit 15, and the storage unit 16.

[0056] [Action of Workpiece Quality Judgment System 1]

[0057] Next, refer to Figures 3-1 1. The operation of the workpiece quality assessment system 1 will be explained. The operation of the workpiece quality assessment system 1 shown in this embodiment includes examples of using… Figure 2A The structure shown represents a workpiece quality assessment system 1.

[0058] Figure 3 This is a flowchart illustrating an example of the processing flow of the workpiece quality judgment system 1. (Refer to...) Figure 3 In step S1, the 3D scanner 101 obtains the 3D shape data of the surface of the workpiece W by measuring the surface of the workpiece W, and supplies the obtained 3D shape data to the computer 102.

[0059] Next, in step S2, the computer 102 (striped projection unit 11) creates a judgment object surface (CAD surface, Computer Aided Design) for quality judgment based on the three-dimensional shape data supplied by the three-dimensional scanner 101. Here, as... Figure 4 As shown, the left door 200 of the car body is used as the judgment object. In the directions shown in the figure, T is the front-to-back direction of the car body, B is the width direction of the car body, and H is the vertical direction of the car body.

[0060] Next, in step S3, the computer 102 (observation angle setting unit 12) sets the observation angle of the projected stripe pattern for quantitative evaluation of the judgment object surface created in step S2 (observation angle setting process).

[0061] Reference Figure 5 and Figure 6 The method for setting the observation angle of the projected stripe pattern relative to the object surface is explained. Figure 5 This is the main view of the left door 200, which serves as the object to be determined. Figure 6 This is a top view of the left door 200, which serves as the object to be determined.

[0062] First, such as Figure 5 As shown, the computer 102 (observation angle setting unit 12) selects the evaluation part Wa to be evaluated and the coordinate values ​​of the evaluation point Ep contained in the evaluation part Wa on the surface of the judgment object surface (left door 200). The method for specifying the evaluation part Wa can be varied depending on the situation. For example, the evaluation part Wa can be arbitrarily specified by the inspector's sensory evaluation, or it can be specified by color mapping the concavity and convexity of the judgment object surface (left door 200) using curvature analysis (Gaussian curvature) to specify the part with a sharp change in concavity and convexity. Alternatively, the evaluation part Wa can be predefined using prior CAE (Computer Aided Engineering) analysis.

[0063] Next, the computer 102 (observation angle setting unit 12) first as follows Figure 6 As shown, a horizontal profile line X passing through the evaluation point Ep is set, and a frontal face D0 with respect to the curvature of the judgment object surface (left door 200) is defined relative to this horizontal profile line X. The frontal face D0 with respect to the curvature is perpendicular to the tangent of the evaluation point Ep on the horizontal profile line X on the evaluation part Wa. Next, the computer 102 (observation angle setting unit 12) sets a predetermined angle +θ1 for the front side of the main body and a predetermined angle -θ1 for the rear side of the main body in the horizontal direction relative to its frontal face D0. This predetermined angle is set to the same angle for both the front and rear sides. As a result, the observation conditions for the front and rear sides can be made consistent for the same evaluation part Wa, enabling appropriate and highly accurate quality judgment.

[0064] The specific angle ±θ reflects the deformation of the evaluation area Wa, and is preferably set to the actual angle from the viewpoint of the user (owner of the car) of the workpiece W. In this embodiment, it is set to ±75°. However, the specific angle ±θ varies depending on the type of workpiece W, the position of the evaluation area Wa, etc., and is not limited to ±75°.

[0065] Next, as Figure 5 As shown, the computer 102 (observation angle setting unit 12) sets multiple different angles for the position relative to the height direction of the judgment object surface (left door 200). Specifically, these are the angles of the observer's standing position H1, squatting position H2, and seated position H3 for the evaluation part Wa.

[0066] The observation angle of the projected stripe pattern is set by combining the angles in the front-back direction (±θ) and the angles in the height direction (heights H1, H2, H3). Therefore, in this embodiment, a total of 6 observation angles can be set. For example, the computer 102 (observation angle setting unit 12) sets the initial value to the angle of the front (+75°) and the height H1 of the standing position. Whenever the time for angle change arrives (step S11 described later), it sequentially changes to the remaining 5 angle combinations (front + height H2, front + height H3, rear + height H1, rear + height H2, rear + height H3). Thus, the observation angle with the most obvious deformation relative to the evaluation part Wa can be selected.

[0067] Next, in step S4, as Figure 7 As shown, the computer 102 (stripe projection unit 11) projects a stripe pattern (projected stripe pattern 300) onto the determination object surface created in step S2. The projection of the stripe pattern can be achieved using the pattern display function in existing 3D CAD software (stripe pattern projection process).

[0068] Next, in step S5, the computer 102 (stripe projection angle setting unit 13) sets the stripe projection angle of the projected stripe pattern 300 according to the curvature of the target surface (left door 200) (stripe projection angle setting process).

[0069] Specifically, firstly, such as Figure 8 As shown, in determining the object surface (left door 200), the direction of curvature with the largest curvature is determined from the directions of curvature with the longer curvature. Next, as... Figure 9 As shown, the angle θ2 formed by the line segments of the projected stripe pattern 300 relative to the horizontal cross-sectional line X along the longer direction of curvature of the evaluation portion Wa on the judgment object surface (left door 200) is set as the stripe projection angle of the projected stripe pattern 300. Figure 8 In the embodiment shown, the projection reference angle is set to 155° as the initial value of the stripe projection angle (θ2). Therefore, in step S5, the computer 102 (stripe projection unit 11) sets 155° as the stripe projection angle (θ2) of the initial projected stripe pattern 300.

[0070] Furthermore, the computer 102 (stripe projection unit 11) can set the stripe projection angle (θ2) of the projected stripe pattern 300 to multiple stages where a predetermined angle is changed each time in the ± direction from the projection reference angle (155°) at each angle change time (step S9 described later). In this embodiment, by changing ±10° each time within a range of ±30° relative to the projection reference angle (155°) as the initial value, the stripe projection angle (θ2) of the projected stripe pattern 300 is set to a total of 7 values: 155°, 165°, 175°, 185°, 145°, 135°, and 125°.

[0071] Next, in step S6, as Figure 10 As shown, the computer 102 (reference stripe production unit 14) smooths the projected stripe pattern 300 on the evaluation area Wa of the judgment object surface (left door 200), thereby producing a reference stripe pattern 301 (reference stripe pattern production process).

[0072] The reference fringe pattern 301 is made as a curve in which the deformation of the workpiece W surface is substantially eliminated relative to the projected fringe pattern 300. Since the reference fringe pattern 301 is made using the projected fringe pattern 300 as a measured line, the computer 102 (reference fringe making unit 14) can make the reference fringe pattern 301 without additional shape data such as reference shape data of the workpiece W.

[0073] Next, in step S7, the computer 102 (quality determination unit 16) compares the projected stripe pattern 300 with the reference stripe pattern 301 at the initial values ​​of the observation angle and the stripe projection angle. Specifically, the computer 102 (quality determination unit 16) calculates the deformation of the projected stripe pattern 300, which is the difference between the projected stripe pattern 300 and the reference stripe pattern 301 on the evaluation area Wa.

[0074] Based on the angle and amplitude between the projected fringe pattern 300 and the reference fringe pattern 301 at the evaluation location Wa, the deformation 300 of the projected fringe pattern 300 is calculated using the following formula.

[0075] Deformation = Angle × Amplitude

[0076] The angle between the projected fringe pattern 300 and the reference fringe pattern 301 is defined as follows. First, as... Figure 11A and Figure 11BAs shown, an arbitrary evaluation point is selected from the reference fringe pattern 301 and defined as reference evaluation point A. Next, a normal perpendicular to the reference fringe pattern 301 is drawn from reference evaluation point A, and the intersection of this normal with the projected fringe pattern 300 is defined as the physical evaluation point B corresponding to reference evaluation point A. Then, the contact vector A of the reference fringe pattern 301 at reference evaluation point A and the contact vector B of the projected fringe pattern 300 at physical evaluation point B are calculated, and the angle ±θ3 formed by these contact vectors A and B is defined as the angle between the projected fringe pattern 300 and the reference fringe pattern 301.

[0077] Computer 102 (quality assessment unit 16) calculates the angle ±θ3 between the projected stripe pattern 300 and the reference stripe pattern 301 for multiple evaluation points. Then, computer 102 (quality assessment unit 16) extracts the absolute value of the calculated angle ±θ3 to be within a range greater than or equal to a predetermined angle. In this embodiment, the predetermined angle is set to 5°. Next, as... Figure 12 As shown, the computer 102 (quality judgment unit 16) sets a group of evaluation points on the projected stripe pattern 300 where the absolute value of the calculated angle ±θ3 is above a specified angle. Figure 12 Groups 1 through 3 are shown.

[0078] The amplitude is determined using the normal length between a reference evaluation point A and the corresponding physical evaluation point B. For example... Figure 11A As shown, when the projected fringe pattern 300 is offset downwards relative to the reference fringe pattern 301, the normal between the selected reference evaluation point A and the physical evaluation point B is defined as the "-direction". For example... Figure 11B As shown, when the projected stripe pattern 300 is offset upward relative to the reference stripe pattern 301, the normal between the selected reference evaluation point A and the physical evaluation point B is defined as the "+ direction".

[0079] As described above, since the angle between the projected stripe pattern 300 and the reference stripe pattern 301 varies in the ± direction, the computer 102 (quality determination unit 16) calculates the amplitude for each of the above groups using the following formula.

[0080] Amplitude = {(-maximum value in the direction) + (+maximum value in the direction)} ÷ 2

[0081] Next, the computer 102 (quality determination unit 16) calculates the deformation of each group based on the maximum value of the angle and the maximum value of the amplitude calculated for each group, using the above formula (angle × amplitude). The calculated deformation value is stored in the storage unit 16.

[0082] Computer 102 (quality determination unit 16) performs deformation calculations for an evaluation region Wa at multiple different viewing angles and multiple different stripe projection angles. Therefore, in step S8, for the stripe projection angles of the projected stripe pattern 300, computer 102 (quality determination unit 16) determines whether a comparison between the projected stripe pattern 300 and the reference stripe pattern 301 at all stripe projection angles within a range of ±30° from the projection reference angle (155°) is complete. Here, the stripe projection angle is set to the initial projection reference angle (155°), therefore step S8 is NO, and the process moves to step S9.

[0083] In step S9, the computer 102 (quality determination unit 16) changes the stripe projection angle from the initial projection reference angle (155°) to, for example, an angle of +10° (165°). Then, the computer 102 (quality determination unit 16) repeats the processes described in steps S5 to S8. For a total of seven stripe projection angles that change by ±10° each time within a range of ±30° from the projection reference angle (155°), when the processes described in steps S5 to S7 are completed, step S8 is set to YES, and the process proceeds to step S10.

[0084] Subsequently, in step S10, the computer 102 (quality judgment unit 16) determines whether there are other viewing angles for the evaluation area Wa of the judgment object surface, that is, whether the comparison between the projected stripe pattern 300 and the reference stripe pattern 301 under all viewing angles has been completed. Here, since the viewing angle is set to the angle of the initial value forward +75° and the height H1 of the standing position, step S10 is NO, and the process moves to step S11.

[0085] In step S11, the computer 102 (quality determination unit 16) changes the observation angle from the initial value of +75° in front and the height H1 of the standing position to, for example, +75° in front and the height H2 of the crouching position. Then, the computer 102 (quality determination unit 16) repeats the processing from steps S3 to S10. When the processing from steps S3 to S8 is completed for a total of six observation angles, step S10 is YES, and the processing moves to step S12.

[0086] In step S12, the computer 102 (quality judgment unit 16) performs quality judgment (quality judgment process) on the evaluation part Wa of the judgment object surface based on the comparison results within the respective ranges of the stripe projection angle and the observation angle.

[0087] That is, the computer 102 (quality judgment unit 16) compares the deformation values ​​calculated for each group within the respective ranges of the stripe projection angle and the observation angle, and uses the largest deformation value as the representative value to determine the quality of the evaluation part Wa of the workpiece W. The quality judgment can be performed by comparing the deformation value used as the representative value with a threshold value, and judging the quality as poor if the deformation value exceeds the threshold value.

[0088] The quality judgment process ends when the quality judgment in step S12 is completed.

[0089] The workpiece quality judgment system 1 described above achieves the following effects.

[0090] In the workpiece quality assessment system 1, the observation angle setting unit 12 sets the observation angle for observing the projected stripe pattern 300 projected onto the workpiece W, the stripe projection angle setting unit 13 sets the stripe projection angle of the projected stripe pattern 300 at the set observation angle, and the reference stripe generation unit 14 generates a reference stripe pattern 301 based on the projected stripe pattern 300 at the set stripe projection angle. Furthermore, the quality assessment unit 15 calculates the difference between the projected stripe pattern 300 and the reference stripe pattern 301 at the stripe projection angle and performs a quality assessment based on the difference. With this structure, the reference stripe pattern 301 is generated based on the projected stripe pattern 300 projected onto the workpiece W, thus automatically determining whether the surface of the workpiece W has deformed without requiring reference shape data for the workpiece W. Since the reference stripe pattern 301 is generated based on the projected stripe pattern 300, an evaluation based on the appearance of the actual object is possible. Since the observation angle of the projected stripe pattern 300 projected onto the workpiece W and the stripe projection angle of the projected stripe pattern 300 are set at each observation angle, quantitative evaluation of the surface of the workpiece W can be performed using various angles, and high-precision quality judgment can be performed without deviation of the evaluation results.

[0091] In the workpiece quality assessment system 1 described above, the stripe projection angle uses the longer curvature direction of the workpiece W as the projection reference angle. The quality assessment unit 15 performs quality assessment by changing the stripe projection angle from the projection reference angle multiple times. According to this structure, since the stripe projection angle is set based on the longer curvature direction of the workpiece W, stable results can be obtained, especially when the assessment target surface is a narrow curved surface. Therefore, a highly versatile workpiece quality assessment system 1 can be provided.

[0092] In the aforementioned workpiece quality assessment system 1, the difference between the projected fringe pattern 300 and the reference fringe pattern 301 is the angle and amplitude formed by the projected fringe pattern 300 and the reference fringe pattern 301. Based on this structure, the difference is calculated by determining the angle and amplitude formed by the projected fringe pattern 300 and the reference fringe pattern 301, thus eliminating the need for complex procedures such as sliding the reference fringe pattern 301 relative to the projected fringe pattern 300. Therefore, a simpler and faster quality assessment can be performed.

[0093] The workpiece quality judgment method described above achieves the same effect as the workpiece quality judgment system 1 described above.

[0094] Figure Labels

[0095] 1. Workpiece Quality Judgment System

[0096] 12 Observation Angle Setting Section

[0097] 13-striped projection angle setting unit

[0098] 14. Standard Stripe Production Department

[0099] 15 Quality Assurance Department

[0100] 300 projection stripe pattern

[0101] 301 Baseline Stripe Pattern

[0102] W workpiece

Claims

1. A method for judging the quality of a workpiece, which judges the quality of the workpiece based on a stripe pattern projected onto the surface of the workpiece, the method being characterized by comprising: The observation angle setting process involves setting the angle at which the projected stripe pattern is projected onto the aforementioned workpiece. The stripe projection angle setting process involves setting the stripe projection angle of the aforementioned projected stripe pattern at the previously set observation angle. The reference stripe production process involves creating a reference stripe pattern based on the aforementioned projected stripe pattern under the set stripe projection angle. The quality assessment process involves calculating the difference between the projected stripe pattern and the reference stripe pattern at the aforementioned stripe projection angle, and then assessing the quality based on the difference.

2. The workpiece quality judgment method according to claim 1, wherein, The aforementioned stripe projection angle uses the longer direction of the workpiece's curvature as the projection reference angle. The aforementioned quality assessment process involves changing the projection angle of the aforementioned stripes from multiple angles based on the aforementioned projection reference angle to assess the aforementioned quality.

3. The workpiece quality judgment method according to claim 1 or 2, wherein, The aforementioned difference is the angle and amplitude between the aforementioned projected fringe pattern and the aforementioned reference fringe pattern.

4. A workpiece quality assessment system, which assesses the quality of a workpiece based on a stripe pattern projected onto its surface, the workpiece quality assessment system being characterized by comprising: The observation angle setting unit sets the observation angle for observing the projected stripe pattern projected onto the aforementioned workpiece; The stripe projection angle setting unit sets the stripe projection angle of the aforementioned projected stripe pattern at the set viewing angle. The reference stripe production department produces a reference stripe pattern based on the aforementioned projected stripe pattern under the set stripe projection angle. The quality assessment unit calculates the difference between the projected stripe pattern and the reference stripe pattern at the aforementioned stripe projection angle, and performs a quality assessment based on the aforementioned difference.

5. The workpiece quality judgment system according to claim 4, wherein, The aforementioned stripe projection angle uses the longer direction of the workpiece's curvature as the projection reference angle. The aforementioned quality assessment unit performs the aforementioned quality assessment by changing the aforementioned stripe projection angle from the aforementioned projection reference angle to multiple angles.

6. The workpiece quality judgment system according to claim 4 or 5, wherein, The aforementioned difference is the angle and amplitude between the aforementioned projected fringe pattern and the aforementioned reference fringe pattern.

Images