Three-dimensional roundness measurement method and device, electronic equipment and storage medium

Abstract

This specification relates to a three-dimensional roundness measurement method, apparatus, electronic device, and storage medium. The three-dimensional roundness measurement method includes planarizing three-dimensional point cloud data of a workpiece to obtain a planar point cloud of the workpiece; wherein the planar point cloud includes multiple point elements; the shape of the planar point cloud corresponds to preset circumcircle selection conditions; triangulating the planar point cloud to obtain at least one triangular piece composed of multiple point elements; wherein the at least one triangular piece corresponds to at least one circumcircle; among the at least one circumcircle, a target circumcircle satisfying the circumcircle selection conditions is determined; and the roundness tolerance of the workpiece is determined based on the distance from the point elements in the planar point cloud to the contour of the target circumcircle. The embodiments of this specification can utilize triangulation to obtain the target circumcircle of the planar point cloud of the workpiece, thereby accurately obtaining the roundness tolerance of the inner diameter of complex workpieces.

Description

Technical Field

[0001] This specification relates to the field of three-dimensional measurement technology, and in particular to a three-dimensional roundness measurement method, device, electronic device and storage medium. Background Technology

[0002] In 3D vision inspection and measurement projects, roundness tolerance is a crucial parameter for product dimensions. Related technologies primarily use least squares or least-enclosed fitting to obtain an ideal circle for 3D roundness. However, when considering the inner diameter of a complex-shaped workpiece as the ideal element, existing 3D roundness measurement methods struggle to accurately measure the roundness of the inner diameter. Summary of the Invention

[0003] This specification aims to at least partially address one of the technical problems in the related art. To this end, one objective of this specification is to propose a three-dimensional roundness measurement method that utilizes triangulation to obtain the target circumcircle of the workpiece's planar point cloud, thereby accurately obtaining the roundness tolerance of the inner hole diameter of complex workpieces.

[0004] The second objective of this specification is to provide a three-dimensional roundness measuring device.

[0005] The third objective of this specification is to provide a computer-readable storage medium.

[0006] The fourth objective of this specification is to provide an electronic device.

[0007] To achieve the above objectives, a three-dimensional roundness measurement method is proposed in the first aspect of this specification. The three-dimensional roundness measurement method includes: performing planarization processing on the three-dimensional point cloud data of a workpiece to obtain a planar point cloud of the workpiece. The planar point cloud includes multiple point elements; the shape of the planar point cloud corresponds to a preset circumcircle selection condition. The planar point cloud is then triangulated to obtain at least one triangular piece composed of multiple point elements. Each at least one triangular piece corresponds to at least one circumcircle. Among the at least one circumcircle, a target circumcircle that satisfies the circumcircle selection condition is determined. The roundness tolerance of the workpiece is determined based on the distance from the point elements in the planar point cloud to the contour of the target circumcircle.

[0008] According to the three-dimensional roundness measurement method of the embodiments of this specification, by triangulating the planar point cloud of the workpiece, the circumcircle of the obtained triangular mesh is determined to be the circumcircle that meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud as the target circumcircle, so that the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined according to the target circumcircle.

[0009] In some embodiments of this specification, the following steps are used to triangulate a planar point cloud until multiple point elements constitute a triangular patch: constructing a seed triangular patch using three point elements at a specified location in the planar point cloud; growing a first triangular patch based on the seed triangular patch using the point elements in the planar point cloud; and performing mesh regularization on the first triangular patch if the area of ​​the circumcircle of the first triangular patch contains other point elements besides the three point elements of the first triangular patch.

[0010] In some embodiments of this specification, the first triangular piece is subjected to mesh regularization processing, including: deleting the common edge between the first triangular piece and the adjacent second triangular piece; and connecting the target diagonal of the quadrilateral formed by the first and second triangular pieces. The target diagonal is the diagonal of the quadrilateral excluding the common edge.

[0011] In some embodiments of this specification, the seed triangle has preset points. The grown triangles form a triangular mesh. A first triangle is grown based on the seed triangle using point elements in a planar point cloud, including: identifying the target point element closest to the preset point among the point elements that do not yet form a triangle; identifying the point element to be grown among the point elements located at the edge of the triangular mesh; and growing the first triangle using the point element to be grown and the target point element.

[0012] In some embodiments of this specification, the shape of the planar point cloud is a complete circle. Determining a target circumcircle that satisfies the circumcircle selection criteria among at least one circumcircle includes: determining the least-squares circle of the planar point cloud; and selecting the circumcircle with the largest radius and center located inside the least-squares circle among the circumcircles of any triangular patch as the target circumcircle.

[0013] In some embodiments of this specification, the shape of the planar point cloud is an arc; the distance between the circumcircle and multiple point elements is denoted as the offset. Determining the target circumcircle that satisfies the circumcircle selection criteria among at least one circumcircle includes: determining the least-squares circle of the planar point cloud. Among the circumcircles of any triangular patch, the circumcircle whose center is located inside the least-squares circle and whose maximum offset is the smallest is selected as the target circumcircle.

[0014] In some embodiments of this specification, the shape of the planar point cloud is elliptical or random. Determining a target circumcircle that satisfies the circumcircle selection criteria within at least one circumcircle includes: selecting the circumcircle with the largest radius whose center is located inside the convex hull of the planar point cloud from the circumcircles of any triangular piece, as the target circumcircle of the planar point cloud.

[0015] In some embodiments of this specification, the three-dimensional point cloud of the workpiece corresponds to a reference plane. The three-dimensional point cloud data of the workpiece is planarized to obtain a planar point cloud, including: determining a rotation matrix that aligns the plane normal vector of the reference plane with a specified coordinate axis of a preset coordinate system; and performing a rotation transformation on the three-dimensional point cloud data based on the rotation matrix to obtain the planar point cloud.

[0016] To achieve the above objectives, a second aspect of this specification provides a three-dimensional roundness measurement device, comprising: a planarization module for planarizing three-dimensional point cloud data of a workpiece to obtain a planar point cloud of the workpiece. The planar point cloud includes multiple point elements; the shape of the planar point cloud corresponds to preset circumcircle selection criteria. A triangulation module for triangulating the planar point cloud to obtain at least one triangular piece composed of multiple point elements. Each triangular piece corresponds to at least one circumcircle. A selection module for determining a target circumcircle that meets the circumcircle selection criteria among the at least one circumcircle. A determination module for determining the roundness tolerance of the workpiece based on the distance from the point elements in the planar point cloud to the contour of the target circumcircle.

[0017] According to the embodiments of this specification, the three-dimensional roundness measuring device triangulates the planar point cloud of the workpiece and determines the target circumcircle from the circumcircle of the obtained triangular mesh that meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0018] To achieve the above objectives, a third aspect of this specification provides a computer-readable storage medium storing a three-dimensional roundness measurement program, which, when executed by a processor, implements the three-dimensional roundness measurement method of any of the above embodiments.

[0019] According to the computer-readable storage medium of the embodiments of this specification, when the three-dimensional roundness measurement program is executed, it is possible to triangulate the planar point cloud of the workpiece and determine the target circumcircle from the circumcircle of the obtained triangular mesh, which meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0020] To achieve the above objectives, a fourth aspect of this specification provides an electronic device including a memory, a processor, and a three-dimensional roundness measurement program stored in the memory and executable on the processor. When the processor executes the three-dimensional roundness measurement program, it implements the three-dimensional roundness measurement method as described in any of the above embodiments.

[0021] According to the embodiments of this specification, when the processor executes a three-dimensional roundness measurement program, the electronic device can triangulate the planar point cloud of the workpiece and determine the target circumcircle from the circumcircle of the obtained triangular mesh that meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0022] Additional aspects and advantages of this specification will be set forth in part in the description which follows, and in part will be obvious from the description or may be learned by practice of this specification. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a three-dimensional roundness measurement method according to one embodiment of this specification.

[0024] Figure 2 is a schematic diagram of a planar point cloud according to an embodiment of this specification.

[0025] Figure 3 This is a flowchart illustrating a method for triangulating a planar point cloud according to one embodiment of this specification.

[0026] Figure 4 This is a schematic diagram of a planar point cloud-based triangular mesh generation method according to one embodiment of this specification.

[0027] Figure 5 This is a schematic diagram of mesh regularization according to one embodiment of this specification.

[0028] Figure 6 This is a schematic diagram of the target circumcircle of a planar point cloud of different shapes, according to one embodiment of this specification.

[0029] Figure 7 This is a structural block diagram of a three-dimensional roundness measuring device according to one embodiment of this specification.

[0030] Figure 8 This is a structural block diagram of an electronic device according to one embodiment of this specification. Detailed Implementation

[0031] The embodiments of this specification are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this specification, and should not be construed as limiting this specification.

[0032] In 3D vision inspection and measurement projects, roundness tolerance is a crucial parameter for product dimensions. With the increasing diversity of applications, the demand for roundness measurement of complex-shaped workpieces is growing. Existing methods for measuring three-dimensional roundness primarily rely on least-squares circle or minimum containment fitting to obtain the ideal circle of the workpiece. However, when the inner diameter of the workpiece is used as the ideal element, existing least-squares circle or minimum containment fitting methods cannot accurately measure the roundness tolerance of the inner diameter. Therefore, this specification proposes a three-dimensional roundness measurement method to accurately measure the roundness tolerance of the inner diameter of a workpiece.

[0033] like Figure 1 As shown in the embodiments of this specification, the three-dimensional roundness measurement method may include the following steps:

[0034] S110 performs planarization processing on the 3D point cloud data of the workpiece to obtain the planar point cloud of the workpiece.

[0035] The planar point cloud includes multiple point elements; the shape of the planar point cloud corresponds to a preset circumcircle filtering condition.

[0036] Specifically, three-dimensional point cloud data of the workpiece can be acquired using sensors, and the shape of the corresponding planar point cloud after planarization can be predicted in advance based on the distribution of the three-dimensional point cloud data. The three-dimensional point cloud data and the predicted shape of the planar point cloud are then input into a terminal for measuring the three-dimensional roundness of the workpiece.

[0037] In the embodiments of this specification, the shape of the planar point cloud can be categorized into four types: full circle, ellipse, arc, and scattered. Full circle and ellipse planar point clouds, viewed as a whole, are closed point clouds with an outline close to a circle or ellipse; these two shapes generally represent the complete outline of the workpiece. Arcs are part of a full circle shape, usually resulting from only acquiring 3D point cloud data for a portion of the workpiece. Scattered shapes are disordered planar point clouds, typically containing significant noise. Since the definition of roundness for different shapes of planar point clouds differs, corresponding circumscribed circle filtering conditions are preset for different shapes of planar point clouds to accurately determine the roundness tolerance of the workpiece.

[0038] According to the national standard GB / T1182-1996, the roundness tolerance zone is the area between two concentric circles on the same plane whose radius difference is equal to the tolerance value. Therefore, in the embodiments of this specification, after acquiring the three-dimensional point cloud data of the workpiece, the three-dimensional point cloud data can be planarized. The three-dimensional point cloud data is converted into a planar point cloud. The planar point cloud includes multiple point elements. Planarization can be achieved by projecting or rotating the three-dimensional point cloud data. If the point cloud data of the workpiece acquired by the sensor is planar point cloud data located in a plane, then no planarization is required, and roundness measurement can be performed directly based on the input planar point cloud data.

[0039] After obtaining the planar point cloud of the workpiece through planarization, the accurate shape of the planar point cloud can be determined. At this point, it can be verified whether the pre-input predicted shape of the planar point cloud matches the currently determined shape. If they do not match, the predicted shape will be replaced with the shape determined from the planar point cloud. For example, if the predicted shape input along with the 3D point cloud data is a full circle, but the shape of the planar point cloud is determined to be an ellipse after planarization, then the ellipse will be used as the accurate shape, replacing the full circle.

[0040] S120, the planar point cloud is triangulated to obtain at least one triangular patch composed of multiple point elements.

[0041] At least one triangular piece corresponds to at least one circumscribed circle.

[0042] Specifically, any three adjacent point elements in a planar point cloud can be connected to obtain multiple triangles. Multiple triangles can form a triangular mesh. The edges of any two triangles in the triangular mesh do not intersect. Each triangle corresponds to a circumcircle.

[0043] In the embodiments of this specification, in order to ensure accurate determination of the maximum inscribed circle of the planar point cloud, the circumcircle of any triangular piece cannot include any point elements other than the three point elements of that triangular piece.

[0044] S130, in at least one circumcircle, determine the target circumcircle that satisfies the circumcircle screening condition.

[0045] Specifically, based on preset circumcircle selection criteria, the circumcircles of the triangular pieces in the triangular mesh are traversed, and the circumcircle that meets the preset circumcircle selection criteria is determined as the target circumcircle of the workpiece planar point cloud. It is understood that the embodiments in this specification are for determining the inner diameter of the workpiece, and the largest inscribed circle of the planar point cloud is the circle that best fits the inner diameter of the workpiece. Therefore, the target circumcircle can be the circumcircle among multiple circumcircles that is closest to the largest inscribed circle of the workpiece planar point cloud. The diameter of the target circumcircle can be used as the roundness diameter of the inner diameter of the workpiece.

[0046] In the embodiments of this specification, the shape of the planar point cloud includes any one of four types: a full circle, an ellipse, an arc, and a scattered shape. Since the roundness of arcs and scattered shapes is usually not clearly defined, and the actual acquired 3D point cloud data may be incomplete or contain a lot of noise, arcs and scattered shapes are processed separately. That is, the four shapes of planar point clouds—full circle, ellipse, arc, and scattered—can each correspond to a preset circumcircle filtering condition.

[0047] Since scattered planar point clouds cannot describe the closed contours of specific shapes, and considering the actual workpiece, its ideal circle should be located as close as possible inside the convex hull of the planar point cloud. Therefore, the method for determining the target circumcircle of scattered planar point clouds is most similar to that for elliptical planar point clouds. Thus, the same circumcircle selection criteria can be applied to elliptical and scattered planar point clouds.

[0048] S140, determine the roundness tolerance of the workpiece based on the distance from the point element in the planar point cloud to the outline of the target circumcircle.

[0049] Roundness tolerance is the area between two concentric circles on the same plane whose radius difference is equal to the tolerance value. In the embodiments of this specification, the distance from other point elements in the planar point cloud to the center of the target circumcircle minus the radius of the target circumcircle can be used as the distance from the point element in the planar point cloud to the contour of the target circumcircle. Alternatively, the distance from the point element in the planar point cloud to the contour of the target circumcircle can be understood as the offset of the target circumcircle. The maximum offset can be used as the roundness tolerance of the workpiece.

[0050] refer to Figure 2a Hollow circles represent spatial points. Projecting these spatial points onto a reference plane yields solid circles as shown in the figure. The ideal circle illustrated can be understood as the target circumcircle of the embodiments described in this specification. The annular tolerance zone is a circle with a radius equal to the maximum distance from a point element in the planar point cloud to the center of the ideal circle. Point elements located on the annular tolerance zone are considered the maximum offset points of the ideal circle. The distance from this point element to the center of the ideal circle minus the radius of the ideal circle equals the maximum offset of the ideal circle illustrated. Point elements located on the ideal circle are considered the minimum offset points of the ideal circle. The minimum offset of the ideal circle is 0. The circular area of ​​the annular tolerance zone minus the area of ​​the ideal circle can be used as the roundness tolerance of the planar point cloud.

[0051] For example, refer to Figure 2b The diagram shows a planar point cloud of a complete circle type. The circle in the diagram represents the determined target circumcircle. Point element 220 in this planar point cloud is the point element with the largest distance to the center 210 of the target circumcircle. Therefore, point element 220 can be considered as the maximum offset point of the target circumcircle, and the distance 230 from point element 220 to the target circumcircle is the maximum offset of the target circumcircle. Therefore... Figure 2b In the diagram, a circle is drawn with the distance between the center 210 and the point element 220 as the radius, and the center 210 as the center. This circle is... Figure 2a The annular tolerance zone is shown. Subtracting the circular area of ​​the target's circumcircle from the circular area of ​​this annular tolerance zone gives the roundness tolerance of the planar point cloud.

[0052] According to the three-dimensional roundness measurement method of the embodiments of this specification, the planar point cloud of the workpiece is triangulated, and the circumcircle of the resulting triangular mesh is selected as the target circumcircle, which meets the preset circumcircle selection criteria corresponding to the shape of the planar point cloud. In the embodiments of this specification, the target circumcircle is the circle that is closest to the true roundness value of the inner hole diameter of the workpiece. Therefore, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0053] In some embodiments of this specification, such as Figure 3 As shown, the following steps are used to triangulate a planar point cloud until multiple point elements form triangular patches, which may include:

[0054] S310 constructs a seed triangle from three point elements at a specified location in a planar point cloud.

[0055] S320 uses point elements in a planar point cloud to grow the first triangle based on the seed triangle.

[0056] S330, if the area of ​​the circumcircle of the first triangle contains other point elements besides the three point elements of the first triangle, perform mesh regularization processing on the first triangle.

[0057] Specifically, any location in the planar point cloud can be selected as the designated location. For example, three point elements can be selected on the outermost side of the planar point cloud to construct a seed triangle; alternatively, the innermost side of the planar point cloud can be selected as the designated location, and the innermost three point elements can be used to construct the seed triangle. To reduce the possibility of omissions during the generation of triangles between other point elements, the innermost position of the planar point cloud can be selected as the designated location in the embodiments of this specification.

[0058] Using the point elements in the planar point cloud other than the three point elements of the seed triangle, the first triangle is continuously generated based on the seed triangle until any point element in the planar point cloud has formed a triangle with its adjacent point elements.

[0059] Each time a first triangle is generated, the "empty circle characteristic" is checked. In the embodiments of this specification, the "empty circle characteristic" can be understood as determining whether the circumcircle of the first triangle covers any point elements other than the three point elements of the first triangle. If the first triangle does not satisfy the "empty circle characteristic," the first triangle is subjected to mesh regularization processing so that the circumcircle of the processed triangle only covers the point elements at the three vertices of the corresponding triangle face.

[0060] After continuously generating the first triangular pieces and performing "empty circle property" checks and mesh regularization on them, a triangular mesh composed of multiple triangular pieces can be obtained. The edges of any two triangular pieces in the triangular mesh do not intersect, and the circumcircle of each triangular piece only covers the point elements that constitute its three vertices.

[0061] In some embodiments of this specification, the seed triangle has preset points. The grown triangles form a triangular mesh. Growing a first triangle based on the seed triangle using point elements in a planar point cloud may include: identifying the target point element closest to the preset point among the point elements that do not yet form a triangle; identifying the point element to be grown among the point elements located at the edge of the triangular mesh; and growing the first triangle using the point element to be grown and the target point element.

[0062] For example, refer to Figure 4 (a) Select the three innermost point elements 1, 2, and 3 from the planar point cloud to construct a seed triangle. Any point of the seed triangle can be selected as a preset point. In the embodiment of this specification, the center point of the seed triangle is selected as the preset point. Then, the other points in the planar point cloud are labeled according to their distance from near to far. Figure 4 (a) shows a planar point cloud consisting of 18 point elements. Except for point elements 1, 2, and 3 that constitute the seed triangle, the other point elements are labeled from 4 to 18 according to their proximity to the center point of the seed triangle.

[0063] exist Figure 4 (a) shows the planar point cloud, where seed triangles form the initial triangular mesh. Point elements numbered 4 to 18 are all point elements that do not form triangles. Point element 4 is closest to the center point of the seed triangle, therefore, point element 4 is the target point element. In the triangular mesh, the line connecting point element 4 to points 1 and 2 does not intersect the edges of other triangles, while the line connecting point element 4 to point element 3 intersects the edge formed by points 1 and 2 in the seed triangle. Therefore, points 1 and 2 can be identified as the point elements for generation.

[0064] Next, the target point element 4 is connected to the point elements 1 and 2 to be grown, respectively, to generate the first triangular patch composed of point elements 1, 2, and 4. At this point, the triangular mesh consists of two triangular patches.

[0065] The first triangle formed by point element 1, point element 2 and point element 4 is judged for "empty circle characteristic". If the first triangle does not meet the "empty circle characteristic" condition, the first triangle formed by point element 1, point element 2 and point element 4 is subjected to mesh regularization processing.

[0066] By generating the first triangular piece from point element 4 as described above, point elements 5 to 18 are sequentially taken as target point elements, and the corresponding point elements to be grown are determined to generate the first triangular piece.

[0067] It should be noted that after each point element generates the first triangle, the first triangle is subjected to "empty circle characteristic" judgment and mesh regularization processing, and then the first triangle is generated based on the next target point element.

[0068] To reduce the number of missing triangle pieces, it can be done by... Figure 4 The first triangle is generated as shown. (See reference.) Figure 4 (a) Taking point element 18 as the target point element to generate the first triangular piece as an example. The point elements to be grown corresponding to the target point element 18 include point element 14, point element 5, point element 3, point element 7, and point element 13. Starting from the center point of the seed triangular piece, a ray is drawn towards point element 18. Facing the direction of the ray, as... Figure 4 As shown in (b), growth proceeds to the right, connecting the target point element 18 to the point elements 13 and 7 to be grown, located to the right of the ray. Facing the ray direction, as... Figure 4 As shown in (c), growth proceeds to the left, connecting the target point element 18 to the point elements 3, 5, and 14 to be grown, all located to the left of the ray. (Reference) Figure 4 (d) The triangles constructed by point elements 5, 14, and 18, the triangles constructed by point elements 1, 5, and 18, the triangles constructed by point elements 1, 7, and 18, and the triangles constructed by point elements 7, 13, and 8 are all the first triangles generated with point element 18 as the target point element.

[0069] In some embodiments of this specification, mesh regularization of the first triangular piece may include: deleting the common edge between the first triangular piece and the adjacent second triangular piece; and connecting the target diagonal of the quadrilateral formed by the first and second triangular pieces; wherein the target diagonal is the diagonal of the quadrilateral other than the common edge.

[0070] refer to Figure 5 (a) The circumcircle of the first triangle formed by point elements 16, 8, and 11 covers point element 4. Therefore, it can be determined that the first triangle formed by point elements 16, 8, and 11 does not meet the "empty circle characteristic". Therefore, the first triangle can be meshed.

[0071] For example, refer to Figure 5 (b) The second triangle adjacent to the first triangle formed by point elements 16, 8, and 11 is a triangle formed by point elements 11, 8, and 4. The first and second triangles form a quadrilateral with points 4, 8, 16, and 11 as vertices. The edge formed by point elements 8 and 11 is the common edge of the first and second triangles, and also a diagonal of the quadrilateral. Therefore, meshing the first triangle includes: deleting the common edge between the first triangle and the adjacent second triangle, i.e., the edge formed by point elements 8 and 11; connecting point elements 4 and 16; the edge formed by point elements 4 and 16 being the target diagonal of the quadrilateral; and the target diagonal formed by point elements 4 and 16 being another diagonal of the quadrilateral besides the common edge formed by point elements 8 and 11.

[0072] In some embodiments of this specification, the shape of the workpiece is a complete circle. Determining a target circumcircle that satisfies the circumcircle selection criteria in at least one circumcircle includes: determining the least-squares circle of the planar point cloud. In the circumcircle of any triangular piece, the circumcircle with the largest radius and its center located inside the least-squares circle is selected as the target circumcircle.

[0073] For example, refer to Figure 6 (a) When the shape of the planar point cloud is a full circle, the least squares circle of the planar point cloud is first determined by the least squares fitting method, such as... Figure 6 (a) The circle is represented by the dashed line. Traverse the circumcircles of any triangle in the planar point cloud to determine the circumcircle whose center lies inside the least squares circle. Among the circumcircles whose centers lie inside the least squares circle, determine the circumcircle with the largest radius as the target circumcircle, such as... Figure 6 (a) The circle represented by the solid line.

[0074] In some embodiments of this specification, the shape of the workpiece is an arc. The distance between the circumcircle and multiple point elements is denoted as the offset. Determining the target circumcircle that satisfies the circumcircle selection criteria in at least one circumcircle includes: determining the least-squares circle of the planar point cloud. In the circumcircle of any triangle, the circumcircle whose center is located inside the least-squares circle and whose maximum offset is the smallest is selected as the target circumcircle.

[0075] For example, refer to Figure 6(b) When the shape of the planar point cloud is an arc, since the planar point cloud with an arc shape is usually due to the acquisition of incomplete 3D point cloud data, and the arc is generally part of a whole circle, in the embodiments of this specification, the screening conditions for the circumcircle of the arc and the whole circle are similar, and the least squares circle of the planar point cloud can also be determined by the least squares fitting method, such as... Figure 6 (b) The circle is represented by a virtual center. Then, the circumcircle of any triangle in the planar point cloud is traversed to determine the circumcircle whose center lies inside the least squares circle. The maximum offset of the circumcircle whose center lies inside the least squares circle is determined, and the circumcircle with the smallest maximum offset is taken as the target circumcircle. The distance between the circumcircle and the point element is called the offset. The point element in the planar point cloud that is farthest from the circumcircle can be called the point with the maximum offset of the circumcircle, and its farthest distance is the maximum offset.

[0076] In some cases, the shape of a planar point cloud may also be curved. For curved planar point clouds, the circumcircle selection criteria for arc shapes can be referenced.

[0077] In some embodiments of this specification, the shape of the workpiece is an ellipse or a polygon. Determining a target circumcircle that satisfies the circumcircle selection criteria in at least one circumcircle includes: in the circumcircle of any triangular piece, selecting the circumcircle with the largest radius whose center is located inside the convex hull of the planar point cloud as the target circumcircle of the planar point cloud.

[0078] For example, Figure 6 (c) represents a planar point cloud with an elliptical shape. Figure 6 (d) Represents a planar point cloud with a scattered shape. The dashed lines in both figures are formed by connecting the outermost point elements, representing the convex hull of the planar point cloud. The ellipse corresponds to the same circumcircle selection criteria as the planar point cloud with a scattered shape. Traverse any circumcircle in the planar point cloud to determine the circumcircle whose center lies within the convex hull of the planar point cloud. Among the circumcircles whose centers lie within the convex hull, select the circumcircle with the largest radius as the target circumcircle of the planar point cloud.

[0079] In some cases, when performing roundness measurements on large batches of 3D point cloud data of different shapes, planar point cloud data with complete circles and ellipses can be identified first. Then, point cloud data with open shapes resembling arcs can be defined as scattered shapes. The circumscribed circle filtering conditions of the embodiments in this specification apply to any scattered planar point cloud.

[0080] In some embodiments of this specification, the three-dimensional point cloud of the workpiece corresponds to a reference plane. The three-dimensional point cloud data of the workpiece is planarized to obtain a planar point cloud, including: determining a rotation matrix that aligns the plane normal vector of the reference plane with a specified coordinate axis of a preset coordinate system; and performing a rotation transformation on the three-dimensional point cloud data based on the rotation matrix to obtain the planar point cloud.

[0081] In some cases, planarization can generally be achieved by projecting 3D point cloud data onto a preset reference plane to obtain a planar point cloud. In the embodiments of this specification, considering that roundness measurement only requires calculating roundness tolerance and offset, a rotational transformation is used to replace the complex 3D projection calculations. This improves computational efficiency while ensuring equivalent results.

[0082] Specifically, firstly, based on the plane normal vector of the reference plane, a rotation matrix is ​​determined to rotate the plane normal vector to be parallel to a specified coordinate axis of the preset coordinate system. The specified coordinate axis can be any one of the x-axis, y-axis, or z-axis. Based on the rotation matrix, all points in the planar point cloud are rotated. For example, if the obtained rotation matrix is ​​R, then z = Rn, where n is the plane normal vector and z is the z-axis vector. The rotation transformation of all points in the planar point cloud includes: p′ = Rp, where p is the coordinate of the point element, and p′ is the coordinate of the point element after rotation. The planar point cloud is formed by the x and y coordinates of the rotated point cloud.

[0083] Corresponding to the above embodiments, this specification also proposes a three-dimensional roundness measuring device 700, such as... Figure 7 As shown, the three-dimensional roundness measuring device may include:

[0084] The planarization module 710 is used to perform planarization processing on the 3D point cloud data of the workpiece to obtain a planar point cloud of the workpiece. The planar point cloud includes multiple point elements; the shape of the workpiece corresponds to preset circumcircle filtering conditions.

[0085] The triangulation module 720 is used to triangulate a planar point cloud to obtain at least one triangular patch composed of multiple point elements. Each triangular patch corresponds to at least one circumcircle.

[0086] The filtering module 730 is used to determine, among at least one circumcircle, a target circumcircle that meets the circumcircle filtering criteria.

[0087] The determination module 740 is used to determine the roundness tolerance of the workpiece based on the distance from the point elements in the planar point cloud to the contour of the target circumcircle.

[0088] According to the embodiments of this specification, the three-dimensional roundness measuring device triangulates the planar point cloud of the workpiece and determines the target circumcircle from the circumcircle of the obtained triangular mesh that meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0089] In some embodiments of this specification, the triangulation module 720 is further configured to: construct a seed triangle using three point elements at specified locations in the planar point cloud; grow a first triangle based on the seed triangle using the point elements in the planar point cloud; and perform mesh regularization processing on the first triangle if the area of ​​the circumcircle of the first triangle contains point elements other than the three point elements of the first triangle.

[0090] In some embodiments of this specification, the triangulation module 720 is further configured to: delete the common edge between the first triangle and the adjacent second triangle; and connect the target diagonal of the quadrilateral formed by the first triangle and the second triangle. The target diagonal is the diagonal of the quadrilateral other than the common edge.

[0091] In some embodiments of this specification, the seed triangle has preset points. The grown triangles form a triangular mesh. The triangular module 720 is further configured to: determine the target point element closest to the preset point among the point elements that do not form a triangle; determine the point element to be grown among the point elements located at the edge of the triangular mesh; and grow a first triangle using the point element to be grown and the target point element.

[0092] In some embodiments of this specification, the shape of the planar point cloud is a complete circle. The filtering module 730 is also used to: determine the least-squares circle of the planar point cloud. Among the circumcircles of any triangular patch, the circumcircle with the largest radius whose center is located inside the least-squares circle is selected as the target circumcircle.

[0093] In some embodiments of this specification, the shape of the planar point cloud is an arc. The filtering module 730 is also used to: determine the least-squares circle of the planar point cloud. Among the circumcircles of any triangle, the circumcircle with the smallest maximum offset and the center located inside the least-squares circle is selected as the target circumcircle.

[0094] In some embodiments of this specification, the shape of the planar point cloud is elliptical or random. The filtering module 730 is also used to: in the circumcircle of any triangle, select the circumcircle with the largest radius whose center is located inside the convex hull of the planar point cloud as the target circumcircle of the planar point cloud.

[0095] In some embodiments of this specification, the three-dimensional point cloud of the workpiece corresponds to a reference plane. The planarization module 710 is further configured to: determine a rotation matrix that is parallel to a specified coordinate axis of a preset coordinate system by rotating the plane normal vector of the reference plane. Based on the rotation matrix, the three-dimensional point cloud data is rotated to obtain a planar point cloud.

[0096] It should be noted that the above explanation of the embodiments and beneficial effects of the three-dimensional roundness measurement method also applies to the three-dimensional roundness measurement device of the present invention. To avoid redundancy, it will not be elaborated in detail here.

[0097] Corresponding to the above embodiments, this specification also provides a computer-readable storage medium storing a three-dimensional roundness measurement program thereon, which, when executed by a processor, implements the three-dimensional roundness measurement method of the above embodiments.

[0098] According to the computer-readable storage medium of the embodiments of this specification, when the three-dimensional roundness measurement program is executed, it is possible to triangulate the planar point cloud of the workpiece and determine the target circumcircle from the circumcircle of the obtained triangular mesh, which meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0099] Corresponding to the above embodiments, this specification also provides an electronic device.

[0100] Figure 8 This is a structural block diagram of an electronic device according to an embodiment of this specification, such as... Figure 8 As shown, the electronic device 800 includes a memory 804, a processor 802, and a three-dimensional roundness measurement program 806 stored in the memory 804 and executable on the processor 802. When the processor 802 executes the three-dimensional roundness measurement program, it implements a three-dimensional roundness measurement method.

[0101] According to the embodiments of this specification, when the processor executes a three-dimensional roundness measurement program, the electronic device can triangulate the planar point cloud of the workpiece and determine the target circumcircle from the circumcircle of the obtained triangular mesh that meets the preset circumcircle screening conditions corresponding to the shape of the planar point cloud. Thus, the roundness tolerance of the inner hole diameter of the workpiece can be accurately determined based on the target circumcircle.

[0102] It should be noted that the logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (such as a computer-based system, a processor-included system, or other system that can fetch and execute instructions from, an instruction execution system, apparatus, or device). For the purposes of this specification, "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transmit programs for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include: an electrical connection having one or more wires (electronic device), a portable computer disk drive (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and editable read-only memory (EPROM or flash memory), fiber optic devices, and portable optical disc read-only memory (CDROM). Alternatively, the computer-readable medium may be paper or other suitable media on which the program can be printed, since the program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, interpreting, or otherwise processing as necessary, and then stored in a computer memory.

[0103] It should be understood that various parts of this specification can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, it can be implemented using any one or a combination of the following techniques known in the art: discrete logic circuits having logic gates for implementing logical functions on data signals, application-specific integrated circuits (ASICs) having suitable combinational logic gates, programmable gate arrays (PGAs), field-programmable gate arrays (FPGAs), etc.

[0104] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this specification. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0105] In the description of this specification, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this specification and for 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 specification.

[0106] Furthermore, the terms "first," "second," etc., used in the embodiments of this specification are for descriptive purposes only and should not be construed as indicating or implying relative importance, or implicitly specifying the number of technical features indicated in this embodiment. Therefore, features defined with terms such as "first" and "second" in the embodiments of this specification can explicitly or implicitly indicate that the embodiment includes at least one of those features. In the description of this specification, the word "multiple" means at least two or more, such as two, three, four, etc., unless otherwise explicitly specified in the embodiments.

[0107] In this specification, unless otherwise explicitly specified or limited in the embodiments, the terms "installation," "connection," "joining," and "fixing," etc., appearing in the embodiments, should be interpreted broadly. For example, a connection can be a fixed connection, a detachable connection, or an integral part; it can also be a mechanical connection, an electrical connection, etc. Of course, it can also be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication between two components, or the interaction between two components. Those skilled in the art will be able to understand the specific meaning of the above terms in this specification based on the specific implementation.

[0108] In this specification, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0109] Although embodiments of this specification have been shown and described above, it is to be understood that the above embodiments are exemplary and should not be construed as limiting this specification. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this specification.

Claims

1. A method of three-dimensional roundness measurement, characterized by, The method comprises the following steps: plane processing is performed on three-dimensional point cloud data of a workpiece to obtain a plane point cloud of the workpiece; the plane point cloud comprises a plurality of point elements; the shape of the plane point cloud corresponds to a preset circumscribed circle screening condition; triangulation processing is performed on the plane point cloud to obtain at least one triangular patch composed of the plurality of point elements; the at least one triangular patch corresponds to at least one circumscribed circle; a target circumscribed circle that satisfies the circumscribed circle screening condition is determined from the at least one circumscribed circle; a roundness tolerance of the workpiece is determined according to the distance from the point elements in the plane point cloud to the contour of the target circumscribed circle; when the shape of the plane point cloud is a complete circle, the target circumscribed circle that satisfies the circumscribed circle screening condition is determined from the at least one circumscribed circle, which comprises the following steps: a least square circle of the plane point cloud is determined; in the circumscribed circle of any triangular patch, the circumscribed circle with the largest radius and the center inside the least square circle is taken as the target circumscribed circle; when the shape of the plane point cloud is an arc, the distance between the circumscribed circle and the plurality of point elements is recorded as an offset; the target circumscribed circle that satisfies the circumscribed circle screening condition is determined from the at least one circumscribed circle, which comprises the following steps: a least square circle of the plane point cloud is determined; in the circumscribed circle of any triangular patch, the circumscribed circle with the smallest maximum offset and the center inside the least square circle is taken as the target circumscribed circle; when the shape of the plane point cloud is an ellipse or scattered, the target circumscribed circle that satisfies the circumscribed circle screening condition is determined from the at least one circumscribed circle, which comprises the following steps: in the circumscribed circle of any triangular patch, the circumscribed circle with the largest radius and the center inside the convex hull of the plane point cloud is taken as the target circumscribed circle of the plane point cloud.

2. The method of claim 1, wherein, The triangulation processing is performed on the plane point cloud until the plurality of point elements all constitute triangular patches by the following steps: a seed triangular patch is constructed by three point elements at a specified position in the plane point cloud; a first triangular patch is grown on the basis of the seed triangular patch by using the point elements in the plane point cloud; if there are other point elements in the area of the circumscribed circle of the first triangular patch except for the three point elements of the first triangular patch, the first triangular patch is subjected to grid regularization processing.

3. The method of claim 2, wherein, The grid regularization processing of the first triangular patch comprises the following steps: a common edge of the first triangular patch and a second triangular patch adjacent to the first triangular patch is deleted; a target diagonal line of a quadrilateral formed by the first triangular patch and the second triangular patch is connected; the target diagonal line is a diagonal line of the quadrilateral except for the common edge.

4. The method of claim 2, wherein, The seed triangular patch has a preset point; a triangular mesh is constructed by the triangular patches that have been grown; the first triangular patch is grown on the basis of the seed triangular patch by using the point elements in the plane point cloud, which comprises the following steps: a target point element closest to the preset point is determined from the point elements that do not constitute triangular patches; a point element to be grown is determined from the point elements located at the edge of the triangular mesh; the first triangular patch is grown by using the point element to be grown and the target point element.

5. The method of claim 1, wherein, The three-dimensional point cloud of the workpiece corresponds to a reference plane; the three-dimensional point cloud data of the workpiece is subjected to planarization processing to obtain a planar point cloud of the workpiece, comprising: determining a plane normal vector of the reference plane to be rotated to a rotation matrix parallel to a specified coordinate axis of a preset coordinate system; performing rotation transformation on the three-dimensional point cloud data based on the rotation matrix to obtain the planar point cloud.

6. A three-dimensional roundness measuring device characterized by comprising: Comprise: a planarization module for planarizing the three-dimensional point cloud data of the workpiece to obtain a planar point cloud of the workpiece; wherein the planar point cloud comprises a plurality of point elements; the shape of the planar point cloud corresponds to a preset circumscribed circle screening condition; a triangulation module for triangulating the planar point cloud to obtain at least one triangular patch composed of the plurality of point elements; wherein the at least one triangular patch corresponds to at least one circumscribed circle; a screening module for determining a target circumscribed circle that meets the circumscribed circle screening condition in the at least one circumscribed circle; a determination module for determining the roundness tolerance of the workpiece according to the distance of the point elements in the planar point cloud to the contour of the target circumscribed circle; the shape of the planar point cloud is a complete circle, and the target circumscribed circle that meets the circumscribed circle screening condition in the at least one circumscribed circle comprises: determining the least squares circle of the planar point cloud; in the circumscribed circle of any triangular patch, the circumscribed circle with the largest radius and the center inside the least squares circle is taken as the target circumscribed circle; the shape of the planar point cloud is an arc, and the distance between the circumscribed circle and the plurality of point elements is recorded as an offset; the target circumscribed circle that meets the circumscribed circle screening condition in the at least one circumscribed circle comprises: determining the least squares circle of the planar point cloud; in the circumscribed circle of any triangular patch, the circumscribed circle with the smallest maximum offset is taken as the target circumscribed circle; the shape of the planar point cloud is an ellipse or scattered, and the target circumscribed circle that meets the circumscribed circle screening condition in the at least one circumscribed circle comprises: in the circumscribed circle of any triangular patch, the circumscribed circle with the largest radius and the center inside the convex hull of the planar point cloud is taken as the target circumscribed circle of the planar point cloud.

7. A computer readable storage medium characterized in that, A three-dimensional roundness measurement program is stored thereon, and the three-dimensional roundness measurement program is executed by a processor to implement the three-dimensional roundness measurement method of any one of claims 1-5.

8. An electronic device, comprising: Comprise a memory, a processor and a three-dimensional roundness measurement program stored on the memory and executable on the processor, and the processor executes the three-dimensional roundness measurement program to implement the three-dimensional roundness measurement method of any one of claims 1-5.

Images