JP3408114B2 - Solid data correction device, solid data correction method, and recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid data correction device and a solid data correction device for correcting solid data errors and curved surfaces in shape processing such as computer aided design (CAD) and computer aided production (CAM). The present invention relates to a recording medium on which a program for recording is recorded. The device and the recording medium are applied, for example, when correcting an error that occurs due to a difference in accuracy peculiar to a CAD system when data is imported from a CAD system of a different model. Further, the apparatus and the recording medium are applied, for example, when the curved surface data are joined and the gaps existing therebetween are corrected.

[0002]

2. Description of the Related Art As a method for expressing a three-dimensional shape model in a CAD system that handles three-dimensional shapes,
Those using a solid model have become popular. Although several representation methods have been proposed for the solid model, B-Reps that represents an object by topological information that represents the relationship between vertices, edges, and surfaces, and that retains curves and curved surfaces as geometric information of edges and surfaces. (Boundary Represen
station system is generally used.

[0003] In the manufacturing industry, a plurality of solid model-based three-dimensional CAD systems suitable for various subdivided design work processes are used. Furthermore, with the division of labor by cooperation between companies, data between the systems is used. The need for mutual use of is increasing.

When exchanging solid model data between such different CAD systems, a problem is C
This is because the allowable error when geometrically handling shape data differs depending on the AD system, which is a big problem especially when data is transferred from a CAD system having a large allowable error to a small CAD system. That is, in the CAD system of the transmission source, if the geometric distances between the topologically connected faces and between the faces and the ridge line are within the tolerance of the CAD system of the transmission source, it is regarded as complete data with no gap. However, if the distance is larger than the tolerance of the CAD system of the destination, the CAD system of the destination recognizes it as incomplete data with a gap. Even if an attempt is made to perform a shape operation on such data based on the work in charge in the CAD system of the destination, it may not be possible.

Therefore, in order to smoothly realize the exchange of solid data between different CAD systems, it is necessary to correct the accuracy in order to absorb the difference in the allowable error between the two CAD systems.

[0006] Regarding such accuracy correction of solid data, there are the following conventional techniques. 1) A method of changing the tolerance of the entire CAD system according to the error of solid data. 2) A method of holding the tolerance in solid data units, curve units, or curved surface units. 3) A method of regenerating the ridgeline by recalculating the line of intersection between adjacent surfaces.

A method of solving the problem by filling the gap between the surfaces in accordance with the ridgeline of the solid data is conceivable. Regarding this, as an element technique, the gap between the given boundary line and the curved surface is filled. We need a method to modify the curved surface. As such a method, there are the following conventional techniques. 4) A method of filling the gap with another curved surface. 5) A method of newly generating a curved surface from a given boundary line (“A Pental surface surface p”).
match for computer aidedge
ometric design ”, Peter Cha
rrot and John A. Gregory, Co
mputer Aided Geometric De
sign 1 (1984) pp. 87-94). 6) Gregory Patch
Using h), the boundary line is matched with the given boundary line (see "Basics and applications of three-dimensional CAD" by Hiroshi Toriya and Hiroaki Chiyokura (Kyoritsu Publishing Co.)).

[0008]

In the prior art 1), there is a problem that the tolerance accuracy originally possessed by the CAD system cannot be used. Also, the CAD
Cannot coexist with other data created on the system.

As a solution to this problem, there is a conventional technique 2). When operating a plurality of solid data having different holding tolerances into one solid data, what is the tolerance used for the calculation? Therefore, there is a possibility that the tolerance will be inconsistent. Also, to change a CAD system with a single tolerance to this method,
This approach is extremely difficult in practice because most of the database processing and geometric processing of the system needs to be reworked and most systems in use today have only a single tolerance.

The conventional technique 3) is an easy method to be adopted for most systems, but as shown in FIG. Calculation is not possible if the intersection does not occur within the tolerance of the CAD system. Also, there are 4 ridges at one vertex.
When more than two lines are gathered, the edges may not be gathered at one point due to the recalculation of the edges, and if this is solved by changing the phase structure, the edge Y with a minute length is generated (FIG. 7). reference). The ridgeline Y having such a minute length is not desirable because it may hinder the subsequent operation. Also, changing the phase structure can be a problem.

Therefore, a method of fixing the ridge line and filling the gap with the surface is required. At that time, if the conventional technique 4) is used, a minute curved surface will be generated, and like the above-mentioned ridge line Y having a minute length, it may hinder subsequent operations, which is not desirable. When the conventional technique 5) is used, the gap can be finely filled, but the original curved surface shape is ignored. Using the conventional technique 6), the gap can be filled up neatly and the shape of the original curved surface can be inherited inside the curved surface, but it can be used only when the boundary line matches the boundary of the defined rectangular area of the curved surface. There is a constraint.

The present invention has been made in view of the circumstances as described above, and an object thereof is to provide a CAD of a different model without significantly changing the basic part of the existing CAD system.
It is an object of the present invention to provide a solid data correction device and a recording medium having the program recorded therein, which realizes conversion of solid data from a system, in particular, a CAD system having low tolerance accuracy, while inheriting the original shape characteristics without any trouble.

[0013]

The solid data correction device of the present invention eliminates the shape error existing inside solid data.
A solid data correcting device for correcting the error measuring means for measuring the error of the internal solid data, the error meter
It is judged by the measuring means that it is far from the connected curved surface.
Connect the solid data ridgeline to the ridgeline.
A ridge line recalculation unit that recalculates by recalculating the intersection line of the curved surface and a ridge line that is a vertex apart from the ridge line and that is connected
If there are 3 or less, the vertices of the solid data are
By recalculating the intersection point of, the recalculating vertex recalculation means and the ridges that are distant from the ridge and are connected are 4
In the case of more than this number, the ridge line correction means for correcting the ridge line of the solid data to the vertices and the curved surface of the solid data
Curved surface correction means for correcting according to the corrected ridge line is provided. The solid of the present invention
The data correction method is the shape existing inside the solid data.
A solid data correction method that corrects the error
Determining whether is away from the surface,
Connect to the ridgeline that is far from the curved surface
Recalculate the ridgeline by recalculating the intersection of two curved surfaces
Connect to a step that is a vertex away from the edge
If the number of ridges is 3 or less, re-estimate the vertex and the intersection of the ridges.
The step of recalculating by calculating
If there are four or more ridge lines that are connected and are connected, the ridge line
To match the vertices, and
The step of modifying the curved surface according to the formed ridge line.
It is characterized by that.

Solid data correction of the present invention having the above configuration
According to the apparatus and the method , the shape error inherent in the solid data converted from the different CAD system or the shape error internally generated in the solid data creation process is corrected without changing the topological structure of the solid data. It is possible to correct within a permissible error range peculiar to the CAD system while inheriting, and the success rate of correction is significantly increased. In addition, before
Serial ridge recalculating means recalculates the ridge by recalculating the curved intersection line a geometric information of the surface, the apex recalculation means, vertex by recalculating the intersection of the ridge and the ridge recalculates, the curved surface modifying means may be intended to modify the curved surface in accordance with the error between the ridge and the surface. Further, these means may be used depending on the situation of data or the like.

As a result, data can be exchanged between different CAD systems without hindering the shape operation, and the design and production work can be smoothly linked between different CAD systems. Therefore, the upstream data can be used to improve the design efficiency and eventually reduce the cost, thereby improving the concurrent engineering design environment.

The CAD system mentioned here is a computer-aided production (CAM) that handles solid models.
It includes similar systems such as systems and is not limited to a narrow sense.

In the solid data correcting apparatus of the present invention , the curved surface correcting means is a boundary error measuring means for measuring a gap T (t) between the curved surface and a boundary line (ridge line) around the curved surface. , The boundary in the parameter space (u, v) of the surface
Generate a parameter space boundary curve Cuv (t) that represents the coordinates of
Parameter space boundary curve generation means for performing Cuv (t)
L = 0 for the distance l (u, v, t) from (u, v)
The reciprocal of the function f that is 0 when and is monotonically increasing with respect to l
E (u, v, t) proportional to
Divide E (u, v, t) by the integrated value of t) with respect to t
D (u, v, t) which is a value obtained by
It is a value obtained by integrating T (t) with t) and integrating with respect to t.
Curved surface correction amount calculating means for obtaining curved surface correction amount B (u, v)
And the curved surface correction amount B (u, v) as the original curved surface So
Configured to modify the curved surface by adding to (u, v)
You may.

According to this structure, it is possible to generate a smooth modified curved surface while inheriting the shape feature of the original curved surface. Also, at the boundary of the curved surface, the tangent vector
The tor matches the boundary of the original curved surface.

[0019]

Further , in the correction of the curved surface, when the curved surface is adjusted to the boundary line of the surroundings, the trim boundary can be corrected instead of the defined rectangular boundary of the curved surface.
Less restrictive modifications can be made.

[0021]

Furthermore, in the correction of the curved surface, it becomes possible to create a smooth modified shape and a modified curved surface that inherits the shape characteristics of the original curved surface, and it is necessary to make a modification considering the manufacturer's intention regarding the shape. You can

The recording medium of the present invention has the characteristics described above.
Let the computer execute the solid data correction method.
Characterized by remembering programs for
To be

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram showing the configuration of a CAD system equipped with the solid data correction device 9 of this embodiment. This CAD system is a B-Reps type 3
The three-dimensional solid model is used, and the control unit 1 is provided in addition to the solid data correction device 9. Further, the display unit 2, the keyboard unit 3, the tablet unit 4, the file unit 5, the modeling unit 6, and the CAD intermediate file conversion unit 7 are connected to the control unit 1. The CAD intermediate file 8 is connected to the CAD intermediate file conversion unit 7 and the CA
Input / output with the D intermediate file conversion unit 7.

The solid data error correction device 9 as a solid data error correction unit includes a solid data error correction control unit 10 connected to the control unit 1. Further, the solid data error correction control unit 10 includes a solid data error measuring unit 11, a curved line intersection recalculation unit 12, and a vertex recalculation unit 1.
3, the ridge line correction unit 14, the curved surface correction unit 15, and the temporary storage 23 are connected.

The solid data error measuring section 11 measures the error inside the solid data as an error measuring means.
The curved surface intersection line recalculation unit 12 functions as a ridge line recalculation unit that recalculates the ridge line by recalculating the intersection line of the curved surface, which is the geometric information of the surface. The vertex recalculation unit 13 functions as a vertex recalculation unit that recalculates the vertices by recalculating the intersections of the edges. The ridge line correction unit 14 serves as a ridge line correction unit and corrects the ridge line in accordance with the vertices. Then, the curved surface modification unit 15 modifies the curved surface of the solid data according to the error between the ridge line and the surface as a curved surface modification means.

The CAD intermediate file 8 is generally an IG.
It is handled in a standard format such as ES (US ANSI standard) and STEP (ISO standard). The CAD intermediate file 8 passed from another CAD system is read by the CAD intermediate file conversion unit 7. If the solid data read in here requires precision correction, the solid data correction device 9 performs precision correction to obtain corrected solid data. Further, in the case of the solid data created inside the modeling unit 6, if the problem of the error cannot be solved, it is possible to intentionally create the solid data including the error and correct the error by the solid data correction device 9.

The operation of the solid data correction device 9 will be described with reference to the flowchart shown in FIG. It should be noted that each determination part described below is determined based on whether it is within the allowable error range of the CAD system.

First, for one ridgeline in solid data, it is determined whether the ridgeline is separated from the curved surface (step S1). For those that are distant from each other, it is determined whether or not there is a line of intersection between the two curved surfaces connected to the ridge (step S2). In this case, it is determined that there are no lines of intersection for perfectly parallel objects. If there are intersections, the intersections are recalculated (step S3). The calculated result is registered in the temporary storage 23. The above is performed for all ridges (step S4).

Next, for one vertex in the solid data, it is determined whether or not the ridge line connected to this is apart from the vertex (step S5). For those that are determined to be separated, it is determined whether four or more ridge lines are connected to the vertex (step S6). If there are four or more lines, the end points of the ridge are corrected so as to match the vertices (step S7). If the number is three or less, the vertex is regenerated by obtaining the intersection of the ridgelines (step S8). The above is performed for all vertices (step S9).

Next, for one curved surface in the solid data, it is judged again whether or not the ridge line connected to it is distant from the curved surface (step S10). Here, it may be determined whether or not there is a line of intersection that is determined in step S2 and a line of which the ridge line has been corrected in step S7. For those far away,
The ridge line connected to the curved surface is used as a boundary line, and the curved surface is modified accordingly (step S11). The above is carried out for all curved surfaces (step S12).

By the above correction operation, the solid data correction device 9 detects the shape error inherent in the solid data converted from the CAD system of the different model or the shape error internally generated in the solid data creation process in the phase structure of the solid data. C without changing the original shape features
The correction can be performed within the allowable error range peculiar to the AD system, and the success rate of the correction is significantly increased. As a result, it is possible to exchange data between different CAD systems without hindering the shape operation, and the design and production work can be smoothly linked between different CAD systems.

Next, the curved surface correction section 15 will be described in detail. In the curved surface correction unit 15, when the curved surface is corrected to match the boundary line, the boundary line is a trim boundary of the curved surface (a boundary of a shape obtained by cutting the defined curved surface with an arbitrary closed curve on the curved surface).
Given as. Therefore, in the correction of the curved surface, it becomes possible to perform correction with the trim boundary instead of the defined rectangular boundary of the curved surface, and it is possible to perform correction with less restrictions. In addition, the curved surface correction unit 15 disperses the deviation amount between the curved surface and the given boundary (deviation between the point on the given boundary and the corresponding point on the curved surface) from the boundary to the inside so as to obtain a smooth corrected shape. And a curved surface shape that inherits the shape characteristics of the original curved surface.

More specifically, as shown in FIG. 3, the curved surface modification section 15 is provided with a curved surface modification control section 16. The curved surface correction control unit 16 is connected to the curved surface data 17, the three-dimensional boundary curve data 18, the parameter space boundary curve generating unit 19, and the modified curved surface generating unit 20. A curved surface correction amount calculation unit 21 is connected to the corrected curved surface generation unit 20, and a boundary error measurement unit 22 is connected via the curved surface correction amount calculation unit 21.

The curved surface correction control unit 16 reads the curved surface data 17 and the three-dimensional boundary curve data 18, and the parameter space boundary curve generation unit 19 generates a boundary curve in the parameter space. As a generation method in this case, the coordinates in the curved surface parameter space of the point having the shortest distance from each point on the three-dimensional boundary curve data 18 to the curved surface data 17 are calculated, and the coordinates are connected to form the boundary curve in the curved surface parameter space. There is a way to generate. If the original boundary line has a parameter space boundary curve, it can be used. Based on these data, the modified curved surface generator 20 generates a modified curved surface.

The boundary error measuring unit 22 measures the gap between the curved surface and the surrounding boundary line as the boundary error measuring means, and the corrected curved surface generation unit 20 functions as the corrected curved surface generation unit between the curved surface and the boundary line. Considering all the gaps, generate a modified curved surface that smoothly fills the gaps. Further, the curved surface correction amount calculation unit 21 calculates the correction amount of the curved surface based on the measurement of the boundary error measurement unit 22. Specifically, the modified curved surface generation unit 20, the curved surface modification amount calculation unit 21, and the boundary error measurement unit 22.
In, the modified curved surface is obtained as follows (see FIG. 4).

The coordinates of the modified curved surface in the curved surface parameter (u, v) are S (u, v), and the coordinates of the original curved surface are S ₀ (u, v
v), and the correction amount of the coordinates is B (u, v), S (u,
v) is calculated by the following formula.

[0039]

[Equation 1]

The correction amount B (u, v) is the error amount T (t) at the point on the parameter space curve Cuv (t) at the curved surface boundary.
(The error amount T (t) is measured by the boundary error measuring unit 22), and is calculated by the following formula so that all can be taken into consideration.

[0041]

[Equation 2]

Note that t _s and t _e are the starting point parameter and the ending point parameter of C _uv (t), respectively. Also, D
(U, v, t) is a coefficient when considering T (t).

When T (t) = const , B (u, v)
In order to be = T, the following formula needs to be established.

[0044]

[Equation 3]

Therefore, here, the coefficient E (u, v, t)
Using,

[0046]

[Equation 4]

Let us say.

When the curved surface parameter (u, v) is a point on C _uv (t) and the curve parameter at that time is t ₀ ,

[0049]

[Equation 5]

Must be: In order to do so, the following conditions must be met.

[0051]

[Equation 6]

To satisfy the above equation, the following equation is given.

[0053]

[Equation 7]

Where l (u, v, t) is C _uv (t)
And (u, v). A is an appropriate constant. Further, f (l) is a function that becomes 0 when l = 0 and increases as the value of l increases. For example,

[0055]

[Equation 8]

It is If this equation is adopted, D
Since (u, v, t) becomes a singular point at a point where l (u, v, t) = 0 (that is, on the boundary line), the equation (4) is directly used as a special process in this case.

The curved surface thus obtained inherits the features of the shape inside the curved surface to some extent as shown in the sectional view of FIG. In FIG. 5, the cross section of the definition curved surface of the original curved surface is shown by 24, and the cross section of the modified curved surface is shown by 25. Further, 26 is a boundary line of the curved surface.

As described above, in the correction of the curved surface by the curved surface correction section 15, it is possible to correct the curved surface not by the defined rectangular boundary but by the trim boundary, and while inheriting the shape feature of the original curved surface. , It becomes possible to generate a smooth modified curved surface.

Further, the obtained corrected curved surface has the following characteristics at the boundary of the curved surface. The coordinates match the three-dimensional curve that represents the boundary. The tangent vector and the curvature vector match those of the original curved surface.

According to the above characteristics, this modified curved surface cannot be changed to one in which the tangent vector and the curvature vector of the boundary portion are designated. However, in the equation for obtaining the tangent vector and the curvature vector, (2)
It can be changed by adding the same one as the expression.

The correction of solid data by the solid data correction device 9 described above may be executed by supplying a solid data correction program to the CAD system (computer).

FIG. 8 is a diagram showing the appearance of such a CAD system. As shown in FIG. 8, a computer main body 81, a display device 82, a magnetic tape device 83 on which a magnetic tape 84 is mounted, a keyboard 85, a mouse 8
6. CD-ROM device 8 in which CD-ROM 88 is mounted
7 and a communication modem 89. Then, the solid data correction program shown in FIG. 2 is executed by supplying the solid data correction program to the computer main body 81 by a recording medium such as a magnetic tape or a CD-ROM. The solid data correction program may be supplied to the computer main body 81 from another computer via a communication circuit and a communication modem, or may be recorded in a hard disk included in the computer main body 81.

[0063]

[0064]

As described above, the solid data of the present invention
According to the correction device and method, a shape error inherent in solid data converted from a CAD system of a different model or a shape error internally generated in the solid data creation process can be corrected without changing the topological structure of the solid data. Can be corrected within the allowable error range peculiar to the CAD system, and the success rate of the correction is significantly increased.

Therefore, it becomes possible to exchange data between different CAD systems without hindering the shape operation.
This has the effect of smoothly linking design and production work between AD systems.

[0066]

The solid data correction device and the solid data correction device of the present invention are also provided.
According to this method, it is possible to generate a smooth modified curved surface while inheriting the shape feature of the original curved surface.

[0068]

Further, in the case of modifying a curved surface, when the curved surface is modified in accordance with the peripheral boundary line, the trim boundary can be modified instead of the defined rectangular boundary of the curved surface, and modification with less restrictions is performed. be able to.

[0070]

Further, in the correction of a curved surface, it becomes possible to create a smooth modified shape and also a modified curved surface that inherits the shape characteristics of the original curved surface, and it is necessary to make a modification considering the manufacturer's intention regarding the shape. You can

The recording medium of the present invention is a solid medium as described above.
A program for causing a computer to execute the data correction method is recorded.

As a result, the computer can be made to modify the solid data as described above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a CAD system including a solid data correction device according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the solid data correction device.

FIG. 3 is a block diagram showing a configuration of a curved surface correction unit provided in the solid data correction device.

FIG. 4 is a graph for explaining a method of calculating a modified curved surface in the curved surface modification unit.

FIG. 5 is an explanatory diagram showing a cross-sectional shape of an original curved surface and a cross-sectional shape of a corrected curved surface by the curved surface correction unit.

FIG. 6 is an explanatory diagram for explaining a conventional technique and showing an example in which a line of intersection of curved surfaces is not obtained.

FIG. 7 is an explanatory diagram of a conventional technique showing an example in which four or more ridge lines are gathered at one vertex, (a) shows a state in which the vertices and the end points of the ridge lines do not match, and (b) adds ridge lines. The vertices and the end points of the ridges are made to coincide with each other.

FIG. 8 is an external view illustrating an example of a recording medium of the present invention.

[Explanation of symbols]

9 Solid data correction device 10 Solid data error correction control unit 11 Solid data error measuring unit (error measuring means) 12 Curved line intersection recalculation unit (ridge line recalculation means) 13 Vertex recalculation unit (vertex recalculation means) 14 Ridge line correction section (ridge line correction means) 15 Curved surface correction section (curved surface correction means) 16 Curved surface correction controller 17 Curved surface data 18 3D boundary curve data 19-parameter space boundary curve generator 20 Modified Curved Surface Generation Unit (Modified Curved Surface Generation Means) 21 Curved Surface Correction Amount Calculation Unit 22 Boundary error measuring unit (boundary error measuring means) 23 Temporary storage Definition of 24-dimensional curved surface Cross section of curved surface 25 Modified surface definition Cross section of curved surface 26 boundary of curved surface 84 magnetic tape 88 CD-ROM

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G06F 17/50 JISST file (JOIS)

Claims (4)

(57) [Claims] 1. A shape error existing inside solid data.
A solid data correction device for correcting the error, which is separated from an error measuring means for measuring an error inside the solid data and a curved surface connected by the error measuring means.
Connect the solid data edge determined to be to the edge
By recalculating the intersection line of the two curved surfaces, the ridge line recalculating means for recalculating and the ridge lines which are vertices apart from the ridge line and connected are three or more.
In the case below, the vertex of the solid data, the intersection of the above-mentioned edge
By recalculating, the vertex recalculating means for recalculating, and the vertices that are far from the ridge and are connected are four or more.
In the above case, the solid line is provided with a ridge line correcting means for correcting the ridge line of the solid data to match the apex, and a curved surface correcting means for correcting the curved surface of the solid data to match the ridge line corrected. Data correction device. 2. The curved surface correction means is a boundary error measuring means for measuring a gap T (t) between the curved surface and a boundary line around the curved surface, and coordinates of the boundary line in the curved surface parameter space (u, v).
For generating a parameter space boundary curve Cuv (t) representing
The parameter space boundary curve generating means is paired with the distance l (u, v, t) between Cuv (t) and (u, v).
Then, when l = 0, it is 0 and monotonically increases with respect to l.
E (u, v, t) proportional to the reciprocal of the function f is obtained, and
E (u, v, t) is the integrated value of t with respect to E (u,
D (u, v, t), which is the value obtained by dividing v, t),
Note that T (t) is added to D (u, v, t) and t
A curved surface for which a curved surface correction amount B (u, v) that is an integrated value is obtained
Correction amount calculating means, and the curved surface correction amount B (u, v) is used as the original curved surface So (u, v).
A curved surface characterized by modifying the curved surface by adding to
The solid data correction device according to claim 1, which is a correction means . 3. A shape error existing inside solid data.
A Soriddode over data correction method of correcting, determining whether the edge line is away from the curved surface
And connect to the ridgeline that is far from the curved surface
Recalculate the ridgeline by recalculating the intersection of two curved surfaces
Steps and three or more ridges that are vertices away from the ridge and are connected
Recalculate the vertices and intersections of the ridges if
Then, the step of recalculating and the number of ridges that are vertices that are distant from the ridge and are connected to
Modifying ridge to fit the apex if above
And a step of modifying a curved surface to match the modified edge line
A method for correcting solid data, comprising: 4. The solid data correction method according to claim 3.
Stores a program that causes a computer to execute
Storage medium.