Solid data corrector and recording medium

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention is a recording medium in which a solid data correction device for correcting errors and curved surfaces of solid data and a program for correcting solid data are recorded in shape processing such as computer-aided design (CAD) and computer-aided manufacturing (CAM). Regarding. The device and the recording medium are applied, for example, when correcting an error generated due to a difference in accuracy peculiar to a CAD system when data is imported from a heterogeneous CAD system. Further, the device and the recording medium are applied, for example, when correcting the gap existing between the curved surface data when they are joined together.

【0002】

[Conventional technology]

In CAD systems that handle 3D shapes, those that use solid models are becoming widespread as a method of expressing the 3D shape model. Several representation methods have been proposed for the solid model, but B-Reps represents an object with phase information that represents the relationship between vertices, ridges, and faces, and holds curves and curved surfaces as geometric information for ridges and faces. It is generally based on the (Boundary Representation) method.

【0003】

In the manufacturing industry, multiple solid model-based 3D CAD systems suitable for various subdivided design work processes are used, and with the division of labor through collaboration between companies, mutual use of data between systems is used. The need for is increasing.

【0004】

The problem when exchanging solid model data between such different CAD systems is that the tolerance when handling shape data geometrically differs depending on the CAD system, and the CAD system with a particularly large tolerance has a large tolerance. It becomes a big problem when passing data from to a small CAD system. That is, in the source CAD system, if the geometric distances between the faces and the surfaces and the ridges that are connected in phase are within the tolerance of the source CAD system, it is regarded as complete data without gaps. However, if the distance is larger than the tolerance of the destination CAD system, the destination CAD system will recognize 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 of the destination CAD system, it may not be possible.

【0005】

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

【0006】

Conventional techniques for correcting the accuracy of such solid data include the following. 1) How to change the tolerance of the entire CAD system according to the error of solid data. 2) A method of holding the margin of error in solid data units, curve units, or curved surface units. 3) A method of regenerating a ridgeline by recalculating the line of intersection between adjacent faces.

【0007】

In addition, a method of filling the gap between the surfaces according to the ridgeline of the solid data can be considered, but as an elemental technology, the curved surface is filled so as to fill the gap between the given boundary line and the curved surface. I need a way to fix it. As such a method, conventional techniques include the following. 4) How to fill the gap with another curved surface. 5) How to generate a new curved surface from a given boundary line (see "A pentagonal surface patch for computer aidedgeometric design", Peter Charrot and John A. Gregory, Computer Aided Geometric Design 1 (1984), pp. 87-94). 6) A method of matching the boundary line with the given boundary line using the Gregory Patch (see "Basics and Applications of 3D CAD" by Hiroshi Toriya and Hiroaki Chiyokura (Kyoritsu Shuppansha)).

【0008】

[Problems to be Solved by the Invention]

The conventional technique 1) has a problem that the permissible accuracy originally possessed by the CAD system cannot be used. In addition, it cannot coexist with other data created on the CAD system.

【0009】

There is a conventional technique 2) as a solution, but when manipulating multiple solid data with different retention tolerances into one solid data, there is a problem of how to use the tolerance for the calculation. Yes, there may be inconsistencies in tolerance. Also, changing a CAD system with a single margin of error to this method would require reworking most of the system's database and geometric processing, and most systems in use today are single. This method is extremely difficult in practice because it has only a margin of error.

【0010】

For most systems, the prior art 3) is an easy method to adopt, but as shown in Fig. 6, when a part X where two curved surfaces are parallel occurs at the part that should be the line of intersection, the destination CAD system It cannot be calculated if they do not intersect within the permissible error range. Also, if four or more ridgelines are gathered at one vertex, those ridgelines may not be gathered at one point due to recalculation of the ridgelines, and if this is solved by changing the phase structure, the ridgeline Y of a minute length will be obtained. It will be generated (see Figure 7). Such a minute length ridge line Y is not desirable because it may interfere with subsequent operations. Also, changing the phase structure can be a problem.

【0011】

Therefore, a method of fixing the ridgeline and filling the gap with the surface is required. At that time, if the prior art 4) is used, a minute curved surface is generated, which is not desirable because it may interfere with the subsequent operation like the above-mentioned minute length ridge line Y. By using the conventional technique 5), the gap can be filled neatly, but the shape of the original curved surface is ignored. By using the prior art 6), the gap can be filled 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 restriction.

【0012】

The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a heterogeneous CAD system, particularly a CAD system having low permissible accuracy, without making major changes to the basic parts of an existing CAD system. It is an object of the present invention to provide a solid data correction device that realizes conversion of solid data of the above without any trouble while inheriting the original shape features, and a recording medium on which the program is recorded.

【0013】

[Means for solving problems]

The solid data correction device according to the invention of claim 1 has an error measuring means for measuring an error inside the solid data, a ridgeline recalculating means for recalculating the ridgeline of the solid data, and a solid, in order to solve the above-mentioned problems. It is provided with a vertex recalculation means for recalculating the vertices of data, a ridge line correction means for correcting the ridgeline of solid data according to the vertices, and a curved surface correction means for correcting the curved surface of solid data according to an error. It is a feature.

【0014】

According to the above configuration, the shape error inherent in the solid data converted from the heterogeneous CAD system or the shape error generated internally in the solid data creation process can be removed from the original shape feature without changing the phase structure of the solid data. While inheriting it, it can be corrected within the tolerance range peculiar to the CAD system, and the success rate of correction becomes significantly higher. The ridge line recalculation means recalculates the ridge line by recalculating the intersection line of the curved surface which is the geometric information of the surface, and the vertex recalculation means recalculates the vertices by recalculating the intersection point of the ridge line and the ridge line. The curved surface correction means may be calculated and the curved surface may be corrected according to the error between the ridge line and the surface. In addition, these means may be used depending on the situation such as data.

【0015】

As a result, data can be exchanged between different types of CAD systems without hindering shape operations, and design and production operations can be smoothly linked between different CAD systems. Therefore, the design efficiency can be improved by utilizing the upstream data, and the cost can be reduced, and the concurrent engineering design environment can be improved.

【0016】

The CAD system referred to here includes a similar system such as a computer-aided manufacturing (CAM) system that handles a solid model, and is not limited to a narrow sense.

【0017】

Further, in the solid data correction device according to the invention of claim 2, in order to solve the above problem, in the configuration of claim 1, the curved surface correction means is used to measure the gap between the curved surface and the surrounding boundary line. It is characterized in that an error measuring means and a modified curved surface generating means for generating a curved surface that smoothly fills the gap in consideration of all the gaps between the curved surface and the boundary line are provided.

【0018】

According to the above configuration, the boundary error measuring means measures the gap between the curved surface and the boundary line, while the modified curved surface generating means smoothly fills the gap. This makes it possible to generate a smooth modified curved surface while inheriting the shape characteristics of the original curved surface.

【0019】

Further, in order to solve the above problem, the solid data correction device according to the invention of claim 3 has the configuration of claim 1 when the curved surface correction means corrects the curved surface in accordance with the surrounding boundary line. The boundary line is characterized in that it is given as a trim boundary of a curved surface.

【0020】

According to the above configuration, when the curved surface correction means corrects the curved surface according to the boundary line, the boundary line given as the trim boundary is treated instead of the definition rectangular boundary of the curved surface. As a result, when modifying a curved surface, it becomes possible to modify the curved surface at the trim boundary instead of the definition rectangular boundary, and it is possible to perform the modification with less restrictions.

【0021】

Further, in order to solve the above problem, the solid data correction device according to the invention of claim 4 uses the curved surface correction means to demarcate the deviation amount between the curved surface and the given boundary in the configuration of claim 3. It is characterized by creating a smooth modified shape by dispersing from to the inside, and creating a curved surface shape that inherits the shape characteristics of the original curved surface.

【0022】

According to the above configuration, it is possible to create a smooth modified shape and a modified curved surface that inherits the shape characteristics of the original curved surface in the modification of the curved surface, and the modification considering the intention of the creator regarding the shape It can be carried out.

【0023】

Further, the recording medium according to the invention of claim 5 includes an error measuring means for measuring an error inside the solid data, a ridgeline recalculation means for recalculating the ridgeline of the solid data, and a vertex recalculation for recalculating the vertices of the solid data. It is characterized by recording a program for causing a computer to execute a calculation means, a ridge line correction means for correcting the ridgeline of the solid data according to an error, and a curved surface correction means for correcting a curved surface of the solid data according to an error. There is.

【0024】

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

【0025】

FIG. 1 is a block diagram showing a configuration of a CAD system including the solid data correction device 9 of the present embodiment. This CAD system uses a B-Reps three-dimensional solid model, and includes a control unit 1 in addition to the solid data correction device 9. Further, a display unit 2, a keyboard unit 3, a tablet unit 4, a file unit 5, a modeling unit 6, and a 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 performs input / output with the CAD intermediate file conversion unit 7.

【0026】

The solid data 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 is connected to the solid data error measurement unit 11, the curved line intersection line recalculation unit 12, the vertex recalculation unit 13, the ridge line correction unit 14, the curved surface correction unit 15, and the temporary storage 23. ing.

【0027】

The solid data error measuring unit 11 measures the error inside the solid data as an error measuring means. The curved line intersection line recalculation unit 12 functions as a ridge line recalculation means for recalculating the ridge line by recalculating the curved surface intersection line which is the geometric information of the surface. The vertex recalculation unit 13 functions as a vertex recalculation means for recalculating the vertices by recalculating the ridge line and the intersection of the ridge lines. The ridge line correction unit 14 corrects the ridge line according to the apex as a ridge line correction means. Then, the curved surface correcting unit 15 corrects the curved surface of the solid data according to the error between the ridge line and the surface as the curved surface correcting means.

【0028】

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

【0029】

The operation of the solid data correction device 9 will be described with reference to the flowchart shown in FIG. In addition, each judgment part described below shall be judged by whether or not it is within the permissible error range of the CAD system.

【0030】

First, for one ridgeline in the solid data, it is determined whether or not the ridgeline is separated from the curved surface (step S1). For those that are separated, it is determined whether or not there is a line of intersection between the two curved surfaces that connect to the ridge (step S2). In this case, it is determined that there is no line of intersection for those that are completely parallel. If there is a line of intersection, recalculate the line of intersection (step S3). The calculated result is registered in the temporary hangar 23. The above is carried out for all ridges (step S4).

【0031】

Next, for one vertex in the solid data, it is determined whether the ridge line connecting to the vertex is separated from the vertex (step S5). For those determined to be separated, it is determined whether or not four or more ridgelines are connected to the vertices (step S6). If there are four or more, correct so that the end points of the ridgeline match the vertices (step S7). If the number is 3 or less, the vertices are regenerated by finding the intersections of the ridges (step S8). The above is carried out for all vertices (step S9).

【0032】

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

【0033】

By the above correction operation, the solid data correction device 9 eliminates the shape error inherent in the solid data converted from the heterogeneous CAD system or the shape error generated internally in the solid data creation process without changing the phase structure of the solid data. , It is possible to make corrections within the tolerance range peculiar to the CAD system while inheriting the original shape features, and the success rate of correction becomes significantly higher. As a result, data can be exchanged between different types of CAD systems without hindering shape operations, and design and production operations can be smoothly linked between different CAD systems.

【0034】

Next, the curved surface correction portion 15 will be described in detail. In the curved surface correction unit 15, when the curved surface is modified according to the boundary line, the boundary line is given as the trim boundary of the curved surface (the boundary of the shape obtained by cutting out the defined curved surface with an arbitrary closed curve on the curved surface). Therefore, when modifying a curved surface, it is possible to modify the curved surface at the trim boundary instead of the definition rectangular boundary, and it is possible to perform the modification with less restrictions. In addition, the curved surface correction unit 15 distributes the amount of deviation between the curved surface and the given boundary (the deviation between the points on the given boundary and the corresponding points on the curved surface) from the boundary to the inside to create a smooth correction shape. And create a curved surface shape that inherits the shape characteristics of the original curved surface.

【0035】

Specifically, as shown in FIG. 3, the curved surface correction unit 15 is provided with a curved surface correction control unit 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 generation unit 19, and the correction curved surface generation unit 20. Further, the curved surface correction amount calculation unit 21 is connected to the correction curved surface generation unit 20, and the boundary error measurement unit 22 is connected via the curved surface correction amount calculation unit 21.

【0036】

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. In this case, the generation method is to calculate the coordinates in the curved surface parameter space of the point having the shortest distance from each point on the 3D boundary curve data 18 to the curved surface data 17, and connect them to create the boundary curve in the curved surface parameter space. There is a way to generate. It is also possible to use a parameter space boundary curve as the original boundary, if it has one. Based on these data, the modified curved surface generation unit 20 generates a modified curved surface.

【0037】

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

【0038】

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

【0039】

[Number 1]

<img file="JPH1069506A_D0001.tif" />【0040】

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

【0041】

[Number 2]

<img file="JPH1069506A_D0002.tif" />【0042】

In addition, t_s, T_eAre each C_uvThe start point parameter and end point parameter of (t). Also, D (u, v, t) is a coefficient when considering T (t).

【0043】

In order for B (u, v) = T when T (t) = T (const), the following equation must hold.

【0044】

[Number 3]

<img file="JPH1069506A_D0003.tif" />【0045】

Therefore, here, using the coefficient E (u, v, t), [0046]

[Number 4]

<img file="JPH1069506A_D0004.tif" />【0047】

far.

【0048】

Surface parameter (u, v) is C_uv(t) When it is the above point, the curve parameter at that time is t₀Then [0049]

[Number 5]

<img file="JPH1069506A_D0005.tif" />【0050】

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

【0051】

[Number 6]

<img file="JPH1069506A_D0006.tif" />【0052】

In order to satisfy the above equation, the following equation shall be given.

【0053】

[Number 7]

<img file="JPH1069506A_D0007.tif" />【0054】

Where l (u, v, t) is C_uvThe distance between (t) and (u, v). Also, A is an appropriate constant. In addition, f (l) is a function that becomes 0 when l = 0 and increases as the value of l increases. For example [0055]

[Number 8]

<img file="JPH1069506A_D0008.tif" />【0056】

Is. If this formula is adopted, D (u, v, t) becomes a singular point at the point where l (u, v, t) = 0 (that is, on the boundary line), so in this case, it is directly treated as a special process. Use equation (4).

【0057】

The curved surface obtained in this way inherits the characteristics of the shape inside the curved surface to some extent, as shown in the cross-sectional view shown in 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 defined curved surface of the modified curved surface is shown by 25. In addition, 26 is the boundary line of the curved surface.

【0058】

As described above, when the curved surface is corrected by the curved surface correction unit 15, it can be corrected by the trim boundary instead of the definition rectangular boundary of the curved surface, and it is smooth while inheriting the shape characteristics of the original curved surface. It becomes possible to generate a modified curved surface.

【0059】

Further, the obtained modified 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.

【0060】

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

【0061】

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

【0062】

FIG. 8 is a diagram showing the appearance of such a CAD system. As shown in FIG. 8, the computer body 81, the display device 82, the magnetic tape device 83 to which the magnetic tape 84 is attached, the keyboard 85, the mouse 86, the CD-ROM device 87 to which the CD-ROM 88 is attached, and the communication modem 89. It has. Then, the solid data correction program is supplied to the computer main body 81 by a recording medium such as a magnetic tape or a CD-ROM, so that the solid data correction shown in FIG. 2 is executed. The solid data correction program may be supplied from another computer to the computer main body 81 via a communication modem via a communication circuit, or may be recorded on a hard disk internal to the computer main body 81.

【0063】

[Effect of the invention]

As described above, the solid data correction device according to the invention of claim 1 has an error measuring means for measuring an error inside the solid data, a ridgeline recalculation means for recalculating the ridgeline of the solid data, and a vertex of the solid data. The configuration includes a vertex recalculation means for recalculating, a ridge line correction means for correcting the ridgeline of solid data according to the vertices, and a curved surface correction means for correcting the curved surface of solid data according to an error.

【0064】

As a result, the shape error inherent in the solid data converted from the heterogeneous CAD system or the shape error generated internally in the solid data creation process is CAD while inheriting the original shape feature without changing the phase structure of the solid data. It can be corrected within the tolerance range peculiar to the system, and the success rate of correction becomes significantly higher.

【0065】

Therefore, it is possible to exchange data between different types of CAD systems without hindering shape operations, and it is possible to smoothly link design and production operations between different CAD systems.

【0066】

Further, in the solid data correction device according to the invention of claim 2, in addition to the configuration of claim 1, the curved surface correcting means includes a boundary error measuring means for measuring a gap between the curved surface and the surrounding boundary line, and a curved surface. The configuration is provided with a modified curved surface generating means for generating a curved surface that smoothly fills the gap in consideration of all the gaps between the boundary line and the boundary line.

【0067】

This makes it possible to generate a smooth modified curved surface while inheriting the shape characteristics of the original curved surface.

【0068】

Further, in the solid data correction device according to the invention of claim 3, in addition to the configuration of claim 1, when the curved surface correction means corrects the curved surface according to the surrounding boundary line, the boundary line is trimmed on the curved surface. It is a configuration given as a boundary.

【0069】

As a result, when modifying a curved surface to match the surrounding boundary line, it is possible to modify the curved surface at the trim boundary instead of the definition rectangular boundary of the curved surface, and it is possible to perform correction with less restrictions. it can.

【0070】

Further, in the solid data correction device according to the invention of claim 4, in addition to the configuration of claim 3, the deviation amount between the curved surface and the given boundary is dispersed from the boundary to the inside by the curved surface correction means. It is a configuration that creates a smooth modified shape and creates a curved surface shape that inherits the shape characteristics of the original curved surface.

【0071】

As a result, when modifying a curved surface, it is 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 possible to perform the modification in consideration of the creator's intention regarding the shape. ..

【0072】

Further, the recording medium according to the invention of claim 5 includes an error measuring means for measuring an error inside the solid data, a ridgeline recalculation means for recalculating the ridgeline of the solid data, and a vertex recalculation for recalculating the vertices of the solid data. A program for causing a computer to execute a calculation means, a ridge line correction means for correcting the ridgeline of the solid data according to an error, and a curved surface correction means for correcting a curved surface of the solid data according to an error is recorded.

【0073】

This makes it possible for the computer to modify the solid data as described above.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the structure of the CAD system provided with the solid data correction apparatus of one Embodiment of this invention.

[Figure 2]

It is a flowchart explaining the operation of the said solid data correction apparatus.

[Fig. 3]

It is a block diagram which shows the structure of the curved surface correction part provided in the solid data correction apparatus.

[Fig. 4]

It is a graph for demonstrating the calculation method of the corrected curved surface in the said curved surface correction part.

[Fig. 5]

It is explanatory drawing which shows the cross-sectional shape of the original curved surface and the cross-sectional shape of the modified curved surface by the said curved surface correction part.

[Fig. 6]

This is an explanatory diagram showing an example in which the line of intersection of curved surfaces cannot be obtained, to explain the prior art.

[Fig. 7]

It is an explanatory diagram of the prior art showing an example in which four or more ridge lines are gathered at one vertex, (a) shows a state where the end points of the vertex and the ridge line do not match, and (b) adds a ridge line to the vertex. It shows the state where the end points of the ridgeline are matched.

[Fig. 8]

It is an external view explaining an example of the recording medium of this invention.

[Explanation of symbols]

9 Solid data correction device 10 Solid data error correction control unit 11 Solid data error measurement unit (error measurement means) 12 Curved line intersection recalculation unit (ridge line recalculation means) 13 Vertex recalculation unit (vertex recalculation means) 14 Ridge line correction part (ridge line correction means) 15 Curved surface correction part (curved surface correction means) 16 Surface correction control unit 17 Surface data 18 3D boundary curve data 19 Parameter space boundary curve generator 20 Corrected curved surface generator (corrected curved surface generating means) 21 Surface correction amount calculation unit 22 Boundary error measurement unit (boundary error measurement means) 23 Temporary hangar 24 Definition of original curved surface Cross section of curved surface 25 Definition of modified curved surface Cross section of curved surface 26 Curved surface border 84 magnetic tape 88 CD-ROM