Part geometric change automatic identification method, system, equipment and medium

Abstract

The invention relates to the technical field of computer aided design, in particular to a part geometric change automatic identification method, system and equipment and a medium. The method comprises the following steps: acquiring three-dimensional model data of a part according to graph numbers before and after the part is changed, and comparing the three-dimensional model data with global feature information to judge whether the part is geometrically changed or not; if the geometric change occurs, establishing an index between points and surfaces according to a topological relation between the vertexes and the surfaces in the part, analyzing an incidence relation between the vertexes and the surfaces, obtaining a set of the vertexes and the surfaces with differences through a matching result of vertex coordinate matching, and identifying an area corresponding to the set of the vertexes and the surfaces as a change area of the part; the part change area is accurately positioned, automatic recognition of part geometric change is achieved, and manual dependence is reduced.

Claims

1. A method for automatically identifying part geometry changes, characterized in that: Obtain the 3D model data of the part based on the drawing numbers before and after the part is changed, and compare it with the global feature information to determine whether the part has undergone geometric changes; If a geometric change occurs, the index between the points and faces is established according to the topological relationship between the vertices and faces in the part, the association between the vertices and faces is analyzed, and the set of vertices and faces with differences is obtained through the matching results of vertex coordinate matching, and the area corresponding to the set of vertices and faces is identified as the changed area of ​​the part.

2. A method for automatically identifying part geometry changes according to claim 1, characterized in that: The specific steps include: Step S1: obtaining the drawing number of the part before the change and the drawing number of the part after the change according to the part engineering change order, and obtaining the corresponding three-dimensional model of the part from the product data management system according to the drawing number of the part before the change and the drawing number of the part after the change; Step S2: obtaining global feature information of the part from the CAD system, and determining whether the part has undergone geometric changes based on the global feature information; Step S3: If a geometric change occurs, obtain all vertices and faces in part p and part q, and create an index from point to face; Step S4: Align the vertex sets of part p and part q, and identify the faces associated with the unsuccessfully matched vertices as the changed areas.

3. A method for automatically identifying part geometry changes according to claim 2, characterized in that: The step S2 specifically includes the following steps: Step S21: Obtaining global feature information of the part from the CAD system; the global feature information of the part includes the surface area S of the part p p , the surface area S of part q q 、The volume V of part p p , the volume V of part q q , the number of surface elements N in part p p and the number of surface elements N in part q q ; Step S22: According to the surface area S p , surface area S q 、Volume V p 、Volume V q 、Number of surface elements p 、Number of surface elements q , set the judgment conditions to determine whether the part has been changed.

4. A method for automatically identifying part geometry changes according to claim 3, characterized in that: The judgment conditions are: Sp = Sq&&Vp = Vq&&Np = Nq ； Among them, && represents logical AND.

5. The method for automatically identifying part geometry changes according to claim 2, characterized in that: The step S3 specifically comprises the following steps: Step S31: If a geometric change occurs, for part p, read all vertex sets Point in part p p ={v p,1 ,v p,2 ,…v p,n }Face collection of noodles p ={ f p,1 ,f p,2 ,…f p,m }, where v and f represent the vertices and faces in the part, respectively, and n and m represent the number of vertices and faces, respectively; Step S32: traverse the face set Face p For each face f in , if Point p If a point v in composes a face f, then add the point v to the vertex index set of the face, that is: index(f ∈ Face p ) = {v丨v ∈ Point p , v ∈ f}; Step S33: traverse the vertex set Point p For each point v in the face set Face, if the point v is p If a face f is included in , then add face f to the index set of vertex v, that is: index(v ∈ Point p ) = {f | f ∈ Face p , v ∈ f}; Step S34: For part q, repeat steps S31-S32 and generate the index of each vertex (v∈Point q ).

6. A method for automatically identifying part geometry changes according to claim 5, characterized in that: The step S4 specifically comprises the following steps: Step S41: For each vertex v in part q q ∈Point q , if any vertex v in part p p ∈Point p If the set conditions are met, the vertex v q Add to set R, that is: R = { v q ∈ Point q 丨 coor(v q )≠ coor(v p ), ∀ v p ∈ Point p}; Among them, coor (v q ) and coor(v p ) represents the vertex v q and v p The three-dimensional coordinate value of Step S42: Obtain the face set formed by all points in the set R, and identify the changed area of ​​the changed drawing number: S1=U v∈Rindex (v); Step S43: For each face f in part q q ∈Face q , if any face f in part p p ∈Face p If the set conditions are met, the face f q Add to set S2, that is: S2 = { f q ∈ Face q 丨 ∀ f p ∈ Face p ,index(Face q )≠ index(Face p )}; Among them, index (Face q )≠index(Face p ) indicates index (Face q ) and index(Face p ) have vertices with different coordinates; Step S44: Combine set S1 and set S2 to identify the changed area of ​​the drawing number after the change, that is: S= S1∪S2.

7. A system for automatically identifying part geometry changes, used to implement the method for automatically identifying part geometry changes as claimed in claim 1, characterized in that: It includes an acquisition unit, a judgment unit, an index establishment unit, and an identification unit; The acquisition unit is used to acquire the three-dimensional model data of the part according to the drawing numbers before and after the part is changed; The judging unit is used to compare with the global feature information to judge whether the part has undergone geometric changes; The index establishment unit is used to establish the index between the points and the faces according to the topological relationship between the vertices and the faces in the part when the geometric changes occur; The identification unit is used to analyze the association between vertices and faces, obtain a set of different vertices and faces through the matching results of vertex coordinate matching, and identify the area corresponding to the set of vertices and faces as the changed area of ​​the part.

8. An electronic device, characterized in that: It comprises a processor and a memory; a computer program is stored in the memory; when the computer program is executed on the processor, the method for automatically identifying part geometry changes as described in any one of claims 1 to 6 is implemented.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions; when the computer instructions are executed, the method for automatically identifying part geometry changes as described in any one of claims 1 to 6 is implemented.

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