Method for measuring three-dimensional size of flow channel of fuel cell polar plate

Abstract

The invention relates to the technical field of three-dimensional size measurement of a battery pole plate flow channel, in particular to a three-dimensional size measurement method of a fuel battery pole plate flow channel, which comprises the following steps of: (1) performing three-dimensional scanning to obtain a point cloud p; (2) performing plane correction on the point cloud to obtain a point cloud; (3) converting the point cloud into a depth map D (x, y) and normalizing and enhancing the depth map D (x, y) into D '(x, y); the method comprises the steps of (1) obtaining a depth map D '(x, y), (2) enhancing the depth map D' (x, y), (3) carrying out flow channel / ridge segmentation on the enhanced depth map D '(x, y), (4) carrying out edge detection and section extraction to obtain a flow channel / ridge region, and (6) respectively calculating the width / depth and ridge width of the flow channel by combining the values of the flow channel / ridge region, and carrying out statistical output.

Description

Technical Field

[0001] This invention relates to the field of three-dimensional dimension measurement technology for battery electrode channels, and particularly to a method for measuring the three-dimensional dimensions of fuel cell electrode channels. Background Technology

[0002] The flow channel structure on the surface of fuel cell plates is crucial for gas transport and hydrothermal management; its three-dimensional dimensions (channel width, depth, ridge width, etc.) directly affect the performance and lifespan of the fuel cell. Currently, commonly used testing methods include:

[0003] Contact coordinate measuring machine (CMM): It has the disadvantages of high accuracy but low efficiency and high cost.

[0004] Optical profilometers have the technical limitation of only being able to measure local areas and being unable to achieve large-area scanning.

[0005] Two-dimensional image detection: It cannot directly obtain depth information.

[0006] Therefore, there is an urgent need for a method to measure the three-dimensional dimensions of fuel cell electrode channels to overcome the above-mentioned shortcomings. Summary of the Invention

[0007] The main objective of this invention is to provide a method for measuring the three-dimensional dimensions of fuel cell electrode flow channels, which enables rapid detection of key dimensions of the electrode flow channels.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for measuring the three-dimensional dimensions of a fuel cell electrode flow channel includes the following steps:

[0010] (1) 3D scanning to obtain point cloud p:

[0011] P = {p i =(x i y i , z i |i = 1, 2, ..., N};

[0012] P: The obtained 3D point cloud set of the electrode surface; p i =(x i y i , z i ): The i-th point in the point cloud, having three-dimensional coordinates (x, y, y). i y i , z i ), where i = 1, 2, ..., N, and N is the total number of points in the point cloud;

[0013] (2) Perform planar correction on the point cloud to obtain the point cloud.

[0014] (3) The point cloud Convert the depth map to D(x,y) and normalize it to enhance it to D'(x,y);

[0015] (4) Perform flow channel / ridge segmentation on the enhanced depth map D'(x,y);

[0016] (5) Edge detection and cross-section extraction are used to obtain the flow channel / ridge region;

[0017] (6) Calculate the width / depth of the flow channel and the width of the ridge based on the values ​​of the flow channel / ridge region above, and output the statistics.

[0018] Preferably, step (4) specifically includes the following steps:

[0019] (4.1) The flow channel region c(x,y) is obtained by adaptive thresholding according to the formula C(x,y)=1{D′(x,y)<T};

[0020] (4.2) Connected regions are labeled using the 8-neighborhood CCL algorithm, and the geometric features of each connected region are calculated. After filtering out noise based on the geometric features, the remaining flow channel set B is the complement of the flow channel regions: R ridge =Ω\U i∈B B i .

[0021] Preferably, the geometric feature includes: the area A of each region. i Slenderness e i =λ max / λ min (Calculated from the eigenvalues ​​of the matrix composed of the second-order central moments of the connected domain), perimeter P i Rectangularity (Rect) i =A i / (bbox i ).

[0022] 4. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 1, characterized in that step (5) includes:

[0023] (5.1) Equidistant section setting: Sections x are set at intervals of Δx in the x-direction. k =x0 + k·Δx;

[0024] (5.2) Edge localization to obtain the flow channel / ridge region: Apply the Canny algorithm to detect the channel mask boundary in each cross section to obtain the left edge y l (k, j), right edge y r (k, j) and the channel / ridge boundary region [y r (k, j), y l (k, j+1)].

[0025] Preferably, the width of the flow channel is represented by W. c (k, j) = |y r (k,j)-y l (k, j)|·s y Calculate, where s y The Y-axis scaling factor; the difference between the depth ridge and the height of the flow channel is calculated using H. c (k, j) = z ridge (k,j)-z channel (k, j) is calculated; the ridge width is given by formula W. r (k, j) = |y l (k, j+1)-y r (k, j)|·s y calculate.

[0026] Preferably, step (2) specifically includes the following steps:

[0027] (2.1) Tilt correction: Fit the reference plane equation ax+by+cz+d=0 using the RANSAC algorithm or the least squares method, and calculate the normal vector n=(a,b,c);

[0028] (2.2) Coordinate transformation: The point cloud coordinate system is standardized by applying the rotation matrix R (to align the normal vector with the Z-axis) and the translation vector T (to align the reference plane with z=0).

[0029] (2.3) Translation correction: Point cloud after correction Ensure that subsequent processing is performed in the standard coordinate system;

[0030] Where, ax+by+cz+d=0: the fitted reference plane equation, a, b, c, d are the parameters of the plane equation, n=(a, b, c): the normal vector of the reference plane, R: the rotation matrix used to align the plane normal vector to the Z-axis direction, R is a three-dimensional rotation matrix, T: the translation vector used to align the reference plane with z=0, and pi: the point in the point cloud after rotation and translation correction.

[0031] Preferably, step (3) specifically includes:

[0032] (3.1) Projection mapping: Project the corrected point cloud onto the XY plane to generate a depth map D(x, y) = z, where (x, y) ∈ Ω, and Ω is the range of the depth map;

[0033] (3.2) Normalization enhancement: through D′(x,y)=(D(x,y)-z min ) / (z max -z min Implement 0-1 range mapping.

[0034] This invention discloses a method for measuring the three-dimensional dimensions of fuel cell electrode flow channels. First, a point cloud P of the product is obtained through 3D scanning, corrected, converted into a depth map, and normalized and enhanced. Then, flow channel / ridge segmentation is performed on the enhanced depth cloud map. The flow channel / ridge region is obtained by edge detection and cross-sectional extraction of the segmented flow channel. The obtained ridge region values ​​are then combined with edge detection and cross-sectional extraction to obtain the flow channel / ridge region, thus realizing a three-dimensional testing method for fuel cell electrode flow channels. This method overcomes the limitations of traditional testing methods in terms of efficiency, coverage, and 3D information acquisition, providing an efficient and accurate digital testing solution for fuel cell electrode flow channel manufacturing. It enables rapid detection of key dimensions of electrode flow channels and is of great significance for improving fuel cell performance consistency and manufacturing process level. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the steps of a method for measuring the three-dimensional dimensions of a fuel cell electrode channel according to the present invention. Detailed Implementation

[0036] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0037] It should be noted that when a component is referred to as "connected to" or "set on" another component, it can be directly on the other component or indirectly on that other component.

[0038] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0039] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise expressly specified. "Several" means one or more, unless otherwise expressly specified.

[0040] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0041] Please see Figure 1 The method for measuring the three-dimensional dimensions of a fuel cell electrode channel according to this embodiment includes the following steps:

[0042] S1, 3D scanning to acquire point cloud p. Specifically, a 3D point cloud P on the electrode surface is acquired using a 3D structured light / laser scanner, where P = {p...} i =(x i y i , z i )|i=1,2,...,N};where, P: the set of three-dimensional point clouds obtained from the surface of the electrode plate. i =(x i y i , z i ): The i-th point in the point cloud, having three-dimensional coordinates (x, y, y). i y i , z i ), where i = 1, 2, ..., N, and N is the total number of points in the point cloud. More specifically, in this embodiment, the point cloud P is acquired by using a small field-of-view, high-precision 3D scanner, scanning multiple times, and fusing the point cloud based on the mechanical coordinates and point cloud features to obtain a large field-of-view, high-precision point cloud of the fuel cell plate, thereby helping to improve the accuracy of the test using this method.

[0043] S2, Tilt Correction. Specifically, plane correction is performed by fitting the reference plane equation ax + by + cz + d = 0 using the RANSAC algorithm or least squares method. The algorithm vector n = (a, b, c) is used through the formula... Calculate the rotation matrix R to align it with the Z-axis. Here, a, b, c, and d are parameters of the plane equation, n = (a, b, c): the normal vector of the reference plane, R: the rotation matrix used to align the plane normal vector to the Z-axis direction, R ∈ SO (3) indicates that R is the rotation matrix in the three-dimensional special orthogonal group, and T: the translation vector used to align the reference plane with z = 0.

[0044] S3, translation correction. Specifically, through the expression... Point cloud obtained by translation correction Align it with the Z-axis.i Points in the point cloud after rotation and translation correction.

[0045] S4, Projection Mapping. Specifically, the corrected point cloud is projected onto the XY plane to generate a depth map D(x, y) = z, where D(x, y) is the depth map generated by projecting the corrected point cloud onto the XY plane, (x, y) represents the coordinates on the XY plane, z is the height value of the corresponding point, (x, y) ∈ Ω, and Ω is the range of the depth map.

[0046] S5, Normalization Enhancement: Through D′(x,y)=(D(x,y)-z min ) / (z max -z min This implements a 0-1 range mapping to enhance image contrast and adapt to the requirements of subsequent image processing algorithms. Where D′(x, y): the normalized and enhanced depth map, z... min and z max These are the minimum and maximum height values ​​in the depth map, respectively.

[0047] S6. The flow channel region c(x, y) is obtained according to the formula C(x, y) = 1{D′(x, y) < T} with an adaptive threshold. Specifically, the depth map is binarized using an adaptive threshold T to generate the flow channel identification function C(x, y) = 1{D′(x, y) < T}.

[0048] S7, Connected regions are labeled using the 8-neighborhood CCL algorithm, and the geometric features of each connected region are calculated. After filtering out noise based on these geometric features, the remaining flow channel set B is the complement of the flow channel regions: R ridge =Ω\U i∈B B i Specifically, connected regions are labeled using the 8-neighborhood CCL algorithm, and the area A of each region is calculated. i Slenderness e i =λ max / λ min (Calculated from the eigenvalues ​​of the matrix composed of the second-order central moments of the connected domain), perimeter P i Rectangularity (Rect) i =A i / (bbox i ), where area A i Total number of pixels in the region, elongation e i =λ max / λ min Morphological description of perimeter P based on eigenvalues ​​of the covariance matrix i Edge pixel count, Rectangularity (Rectangle) i =A i / bbox i: The fill rate of the region and the minimum bounding rectangle. B is the set of channels retained after filtering. Rridge: Ridge region, which is the complement of all channel regions Ui∈B Bi within the range of Ω.

[0049] S8, equidistant section setting. Specifically, sections x are set in the x-direction at intervals of Δx. k = x0 + k·Δx; where x k =x0+k·Δx: x-coordinates of equidistant sections, x0 is the initial x-coordinate, Δx is the section spacing, and k is the section number.

[0050] S9, edge localization to obtain the flow channel / ridge region. Specifically, the Canny method is used to obtain the left and right edges y at the boundary of the channel mask. l (k, j), y r (k, j), (on the Kth cross section, in the jth channel), and taking the ridge boundary pairs between adjacent channels, to obtain the ridge cross section region [y]. r (k, j), y l (k, j+1)].

[0051] S10, calculate the width / depth of the flow channel and the ridge width based on the values ​​of the flow channel / ridge region mentioned above, and output the results statistically. Specifically, the width of the flow channel is represented by W. c (k, j) = |y r (k,j)-y l (k, j)|·s y Calculate, where s y The Y-axis scaling factor; the difference between the depth ridge and the height of the flow channel is calculated using H. c (k, j) = z ridge (k,j)-z channel (k, j) is calculated; the ridge width is given by formula W. r (k, j) = |y l (k, j+1)-y r (k, j)|·s y Calculate the mean, standard deviation, and Pp / Ppk of Wc, Wr, and Hc for all k, j. Wc, Wr, and Hc represent the set of flow channel width, ridge width, and flow channel depth, respectively. The mean indicates the average level of the data, the standard deviation indicates the dispersion of the data, and Pp / Ppk is the process capability index.

[0052] This method leverages the planar nature of fuel cell plates. Step S3 corrects the 3D point cloud and converts it into a depth map. Thresholding, connected component analysis, morphological analysis, and 2D feature filtering methods for 2D images are introduced, significantly improving the algorithm's efficiency, adaptability, and stability. Furthermore, for the segmented target channel or ridge depth image, uniform cross-sections are taken to obtain one-dimensional data at the current cross-section. Edges are then calculated, and the required width, depth, and other dimensional information are analyzed. The 3D point cloud is progressively decomposed into one-dimensional curves for local analysis, minimizing the impact of fuel cell plate warping and skew on measurement accuracy.

[0053] As can be seen from the above description, the present invention provides a method for measuring the three-dimensional dimensions of a fuel cell electrode plate flow channel. After obtaining the point cloud of the fuel cell flow channel plate in three dimensions, it is converted into a depth map after tilt correction and translation correction. After normalization enhancement, the depth cloud map is segmented and the edges and cross sections are extracted. Then, the extracted cross section dimensions are measured and statistically output, thereby realizing the rapid measurement of the three-dimensional dimensions of the fuel cell electrode plate flow channel with high testing accuracy.

[0054] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for measuring the three-dimensional dimensions of a fuel cell electrode flow channel, characterized in that, Includes the following steps: (1) 3D scanning to obtain point cloud p: P={p i =(x i ,y i ,z i )|i=1,2,...,N}; P: The obtained 3D point cloud set of the electrode surface; p i =(x i y i , z i ): The i-th point in the point cloud, having three-dimensional coordinates (x, y, y). i y i , z i ), where i = 1, 2, ..., N, and N is the total number of points in the point cloud; (2) Perform planar correction on the point cloud to obtain the point cloud. (3) The point cloud Convert the depth map to D(x,y) and normalize it to enhance it to D'(x,y); (4) Perform flow channel / ridge segmentation on the enhanced depth map D'(x,y); (5) Edge detection and cross-section extraction are used to obtain the flow channel / ridge region; (6) Calculate the width / depth of the flow channel and the width of the ridge based on the values ​​of the flow channel / ridge region above, and output the statistics.

2. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 1, characterized in that, Step (4) specifically includes the following steps: (4.1) The flow channel region c(x,y) is obtained by adaptive thresholding according to the formula C(x,y)=1{D′(x,y)<T}; (4.2) Connected regions are labeled using the 8-neighborhood CCL algorithm, and the geometric features of each connected region are calculated. After filtering out noise based on the geometric features, the remaining flow channel set B is the complement of the flow channel regions: R ridge =Ω\U i∈B B i .

3. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 2, characterized in that, The geometric features include: the area A of each region. i Slenderness e i =λ max / λ min (Calculated from the eigenvalues ​​of the matrix composed of the second-order central moments of the connected domain), perimeter P i Rectangularity (Rect) i =A i / (bbox i ).

4. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 1, characterized in that, Step (5) includes: (5.1) Equidistant section setting: Sections X are set in the x-direction at intervals of Δx. k =x0 + k·Δx; (5.2) Edge localization to obtain ridge regions: Apply the Canny algorithm to detect the channel mask boundary in each section to obtain the left edge y l (k, j), right edge y r (k, j) and the ridge boundary region [y r (k, j), y l (k,j)].

5. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 4, characterized in that, The width of the flow channel is represented by W. c (k, j) = |y r (k,j)-y l (k, j)|·s y Calculate, where s y The Y-axis scaling factor; the difference between the depth ridge and the height of the flow channel is calculated using H. c (k, j) = z ridge (k,j)-z channel (k, j) is calculated; the ridge width is given by formula W. r (k, j) = |y l (k, j+1)-y r (k, j)|·s y calculate.

6. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 1, characterized in that, Step (2) specifically includes the following steps: (2.1) Tilt correction: Fit the reference plane equation ax+by+cz+d=0 using the RANSAC algorithm or the least squares method, and calculate the normal vector n=(a,b,c); (2.2) Coordinate transformation: Apply rotation matrix R (to align the normal vector with the Z-axis) and translation vector T (to align the reference plane with z=0) to achieve standardization of the point cloud coordinate system; (2.3) Translation correction: Point cloud after correction Ensure that subsequent processing is performed in the standard coordinate system; Where, ax+by+cz+d=0: the fitted reference plane equation, a, b, c, d are the parameters of the plane equation, n=(a, b, c): the normal vector of the reference plane, R: the rotation matrix used to align the plane normal vector to the Z-axis direction, R is a three-dimensional rotation matrix, T: the translation vector used to align the reference plane with z=0, and pi: the point in the point cloud after rotation and translation correction.

7. The method for measuring the three-dimensional dimensions of fuel cell electrode flow channels as described in claim 1, characterized in that, Step (3) specifically includes: (3.1) Projection mapping: Project the corrected point cloud onto the XY plane to generate a depth map D(x,y)=z, where (x,y)∈Ω, and Ω is the range of the depth map; (3.2) Normalization enhancement: through D′(x,y)=(D(x,y)-z min ) / (z max -z min Implement 0-1 range mapping.

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