JP3413733B2 - Method for checking interference between shapes - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for checking interference between shapes in a CAD system, and more particularly to a method for checking interference between shapes suitable for improving efficiency and accuracy of interference checking.

[0002]

2. Description of the Related Art In a general CAD system, it is necessary to check interference between a plurality of objects (check whether or not the objects overlap each other) due to a change in the arrangement of the objects to be processed. As a method of checking interference in a conventional CAD system, a method of checking interference between two objects, which is performed according to the procedure described below, is known.

A certain common coordinate system is determined according to the shape of the object to be compared, and a minimax box (in the case of two dimensions) represented by the minimum and maximum coordinate values in each axial direction of each object in the coordinate system. Is a rectangle and, in the case of three dimensions, a rectangular parallelepiped) is used to perform a rough rough check of the overlap between the objects.

When it is determined by the rough check that there is a possibility of interference, a common coordinate system is determined for each element forming the shape of each object according to the shape of the comparison target element, and the coordinate system concerned is determined. By using the minimax box represented by the minimum and maximum coordinate values of each element in each axis direction in, a rough rough check of the overlap between the elements is performed.

A more strict interference check is performed on the element determined to possibly interfere with the rough check.

[0006]

In the above-described conventional method for checking interference between shapes, it is premised on the idea that "normally, each shape is arranged in order." A rough check is performed using a minimax box whose reference axes are the X-axis, Y-axis, and Z-axis directions in a common coordinate system determined according to the shape. Therefore, even if the minimax box corresponding to one of the shapes to be compared is minimized, the minimax box corresponding to the other shape may be unnecessarily large.

FIG. 4 is a diagram showing the problems of the conventional method for checking the interference between shapes, and FIG.
It uses a dimensional coordinate system. In the figure, the shapes to be compared are a curve G ₁ and a curve G ₂ , which are layout relationships that humans can see at first glance that they do not interfere. However, if the common coordinate system determined when performing the rough check for both shapes is the coordinate system shown by the X ′ axis and the Y ′ axis in the figure, the minimax box 401 set for the curve G ₁ And the minimax box 402 set for the curve G ₂ overlap with each other in the shaded portion 410, and the “curve G ₁
And the curve G ₂ is judged to have a possibility of interference, and there is a problem that a stricter interference check that requires a lot of processing time must be performed.

Therefore, an object of the present invention is to solve the above problems and improve the accuracy of the rough check performed before the strict interference check, thereby reducing the number of executions of the strict interference check. An object of the present invention is to provide a method for checking interference between shapes that can improve the efficiency of.

[0009]

In order to achieve the above object, the method for checking interference between shapes according to the present invention is a CAD method.
When checking the interference between shapes in the system, use the minimax box represented by the minimum and maximum coordinate values in each axis direction of the coordinate system to determine the possibility of interference between shapes. In the check method, after performing the initial setting step and the first step,
If it is determined that there is interference in the first step, the second step is executed. The following processing is performed in each step.

Initial setting step: Optimal first for each of the first and second shapes
And individually set the second minimax coordinate system. A first primary minimax box corresponding to the first shape in the first minimax coordinate system and a second primary mini corresponding to the second shape in the second minimax coordinate system Find each max box.

1st step: The first 1 in the second minimax coordinate system
Find the secondary minimax box corresponding to the next minimax box. The second one in the second minimax coordinate system
It is determined whether or not there is interference between the next minimax box and the second minimax box.

Second step: For an interference area in the second minimax coordinate system, an interference minimax box corresponding to the interference area in the first minimax coordinate system is obtained. The first one in the first minimax coordinate system
The presence or absence of interference between the next minimax box and the interference minimax box is determined.

[0013]

The operation based on the above configuration will be described.

In the interference check method between shapes according to the present invention, when checking the interference between shapes in the CAD system, the shape mutual check is performed by using the minimax box represented by the minimum and maximum coordinate values in each axial direction of the coordinate system. In a method of checking interference between shapes for determining whether there is a possibility of interference between the shapes, after performing the initial setting step and the first step, if it is determined that there is interference in the first step, perform the second step. By executing it, the minimum minimax box can be obtained for each of the pair of shapes to be subjected to the interference check, and in most cases the strict interference check is necessary because the shapes face each other diagonally. For the part, it is possible to check the presence of interference with a simple interference check (rough check), using the minimax box Since the number of executions of the strict interference check is reduced with improved rough check accuracy,
The efficiency of the interference check process can be improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for checking interference between shapes according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing an example of the configuration of a system for realizing the method for checking interference between shapes according to the present invention. In the figure, 101 is a shape data storage unit, 102 is a comparison target shape selection unit, 103 is a minimax coordinate system calculation unit, 104 is a rotation matrix creation unit, 105 is a shape data rotation unit, 106 is a minimax box creation unit, 1
07 is a coordinate conversion matrix creation unit between minimax coordinate systems, 108 is a minimax box interference check unit,
Reference numeral 109 is a strict interference check unit.

In FIG. 1, the shape data storage unit 101 stores shape data created in advance by a CAD system (not shown). Based on the shape data in the shape data storage unit 101, the comparison target shape is stored. Selector 10
2 selects a pair of shape data to be subjected to the interference check. When the pair of shape data is determined, for each shape data, the minimax coordinate system calculation unit 103 uses the average normal vector method that uses the normal vector of the shape data to obtain the optimum coordinate system (in the claim, "Minimax coordinate system") is determined, and the rotation matrix creation unit 104 creates a rotation matrix oriented to the minimax coordinate system, and the shape data rotation unit 105 applies the rotation matrix to the shape data to rotate the shape. Let And
The minimax box creation unit 106 obtains the minimum coordinate value and the maximum coordinate value in each of the X-axis, Y-axis, and Z-axis directions based on the rotated shape data output from the shape data rotation unit 105, and the minimax box Create a box. Since the minimax boxes created for each shape data are expressed in different coordinate systems (minimax coordinate system), the coordinate conversion matrix creating unit 107 between the minimax coordinate systems obtains the coordinate conversion matrix.

Next, using the above coordinate transformation matrix, the first minimax box (first order) corresponding to one shape data is transformed into the other (second) minimax coordinate system, and the coordinate system concerned is transformed. At Minimax Box (Secondary)
Then, the minimax box interference check unit 108 checks whether or not there is interference with the second minimax box (first order) corresponding to the other shape data. At this time, if it is determined that there is no interference, “no interference” is reported as the check result. When it is determined that there is a possibility of interference, the overlapping area (interference area) in the above interference check is converted to the (first) minimax coordinate system to create a (interference) minimax box. ,
The presence or absence of interference with the above-described first minimax box (first order) is checked by the minimax box interference check unit 108. At this time, if it is determined that there is no interference, “no interference” is reported as the check result.
If it is determined that there is a possibility of interference, the strict interference check unit 109 performs a more strict interference check and reports the check result.

In the interference check of the first minimax box, the first minimax box is changed to the second minimax box.
If it is included in the minimax box of or if the coordinate transformation matrix is very similar to the unit matrix, it is determined whether or not strict interference check is performed based on the first interference check result, and the check result is output. It shall be.

FIG. 2 is a flow chart showing the flow of the interference check processing according to FIG. 1, and FIG. 3 is a diagram showing one application example thereof. Hereinafter, description will be given based on FIGS. 2 and 3.

First, in step 201, a pair of shape data F ₁ and F ₂ to be subjected to interference check is acquired. Then, in step 202, the coordinate system for creating the minimax box (first and second minimax coordinate systems) for each shape is obtained by the average normal vector method using the normal vector of each shape data, with each calculates a rotation matrix (a ₁ and a ₂₎ as directed in the minimax coordinate system, the minimax coordinate system by the respective shape data F _1, F ₂ applying a rotation matrix a _1, a ₂ Minimax Box at (1
Next, in step 203, the coordinate transformation matrix between the first and second minimax coordinate systems is obtained from the rotation matrices A ₁ and A ₂ in the following step 203. Above is the processing corresponding to "initialization step" in the claims, in the example of FIG. 3 (a), X ₁ axis and Y ₁ coordinate system representing the axis a first optimal for the shape data F ₁ In the minimax coordinate system,
301 is the first minimax box (primary) for the shape data F ₁ and the coordinate system represented by the X ₂ axis and the Y ₂ axis is the second minimax coordinate system optimal for the shape data F ₂ , 401
Corresponds to the second minimax box (first order) for the shape data F ₂ .

Next, in step 204, the first minimax box (first order) is multiplied by the coordinate transformation matrix to transform into the second minimax coordinate system, and in step 205, the first minimax box (first) in the second minimax coordinate system. The first minimax box (secondary) corresponding to the minimax box (first order) of In the example of FIG. 3B, 401 is the second
Corresponds to the first minimax box (first order), and 302 corresponds to the first minimax box (secondary). Then, in step 206, the first minimax box (secondary) 302 and the second minimax box (primary)
An interference check (rough check) with 401 is performed, and when it is determined that there is no interference, the process branches to step 213 and the result of “no interference” is output. On the other hand, step 206
If it is determined that there is a possibility of interference in step 20,
At 7 it is judged again whether or not the rough check should be performed. In this case, the first minimax box (secondary) 302 is the second
When it is smaller than the minimax box (1st order) 401 of the above, or when the coordinate transformation matrix is very similar to the unit matrix, it is highly likely that interference will be determined even if rough checking is performed again. ,
Assuming that there is a possibility of interference, the process branches to step 212 and a strict interference check is performed. The above is the process corresponding to the "first step" in the claims.

When it is determined in step 207 that the rough check should be performed again, the first minimax box (secondary) 302 and the second minimax box (primary) 401 overlap each other in step 208. Interference area 3
10. In step 209, the interference area 310 is multiplied by the above-mentioned coordinate conversion matrix to be converted into the first minimax coordinate system, and in step 210, the interference minimax box corresponding to the interference area in the first minimax coordinate system. Ask for. In this case, 310 in FIG. 3B is an interference area, and 311 in FIG. 3C is an interference minimax box. Then, in step 211, an interference check (rough check) is performed between the first minimax box (primary) 301 and the interference minimax box 311, and when it is determined that there is no interference, the process branches to step 213, and there is no interference. While outputting the result of
When it is determined that there is a possibility of interference, step 212
Branch to and perform strict interference check. In FIG. 3C, since the first minimax box (first order) 301 and the interference minimax box 311 do not interfere with each other,
The process branches to step 213 and the result of “no interference” is output. The above is the process corresponding to the "second step" in the claims.

In the above-described interference check (rough check), if one of the axis vectors of each minimax coordinate system in the three-dimensional space points in the same direction, the presence or absence of interference between the minimax boxes is more accurate. However, even if all axis vectors point in different directions, the probability of being judged as “no interference” is higher than in the past, so the processing time required for interference check is generally higher. Can be shortened.

As described above, according to this embodiment, the minimum minimax box can be obtained for each of the pair of shapes to be subjected to the interference check, and since the shapes are diagonally opposed to each other, strict interference is caused. For most of the cases where the check was necessary, it is possible to check the presence or absence of interference in the interference check (rough check) in the first and second steps, which improves the accuracy of the rough check using the minimax box and makes it strict. Since the number of times the interference check is executed is reduced, the efficiency of the interference check process can be improved.

[0026]

As described in detail above, according to the interference check method between shapes according to the present invention, when checking the interference between shapes in the CAD system, the minimum and maximum coordinate values in each axial direction of the coordinate system are used. In a method for checking interference between shapes using a represented minimax box to determine whether there is a possibility of interference between shapes, after performing an initial setting step and a first step, the interference is generated in the first step. If it is determined that there is, by performing the second step, the minimum minimax box can be obtained for each of the pair of shapes to be subjected to the interference check, and since the shapes are diagonally facing each other, strictness is required. It is possible to check the presence or absence of interference with a simple interference check (rough check) for the majority of cases that required a complicated interference check. Ri, the number of times of execution of strict interference check with improved accuracy of the rough check is reduced using a minimax box, there is an advantage that it is possible to improve the efficiency of interference check processing.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a system that realizes a method for checking interference between shapes according to the present invention.

FIG. 2 is a flowchart showing a flow of interference check processing according to FIG.

FIG. 3 is a diagram showing an application example of a method for checking interference between shapes according to the present invention.

FIG. 4 is a diagram showing a problem of a conventional method for checking interference between shapes.

[Explanation of symbols]

101 shape data storage unit 102 comparison target shape selection unit 103 minimax coordinate system calculation unit 104 rotation matrix creation unit 105 shape data rotation unit 106 minimax box creation unit 107 coordinate conversion matrix creation unit 108 between minimax coordinate systems 108 minimax box Interference check unit 109 Strict interference check unit

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A 64-26981 (JP, A) JP-A 1-180671 (JP, A) JP-A 3-12787 (JP, A) JP-A 7- 129627 (JP, A) JP-A-7-152807 (JP, A) JP-A-7-262243 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G06F 17/50 628 JISST File (JOIS)

Claims (2)

(57) [Claims] 1. When checking interference between shapes in a CAD system, it is determined whether or not there is a possibility of interference between shapes by using a minimax box represented by minimum and maximum coordinate values in each axial direction of the coordinate system. In the method for checking interference between shapes, the optimum first and second minimax coordinate systems are individually set for each of the first and second shapes, and the first minimax coordinate system is used. Initial setting step for obtaining a first primary minimax box corresponding to the shape and a second primary minimax box corresponding to the second shape in the second minimax coordinate system, respectively. To obtain a secondary minimax box corresponding to the first primary minimax box in the minimax coordinate system of Interference checking method between shaped cross, characterized by comprising: a first step of determining the presence or absence of interference between the secondary Minimax box and the second primary minimax box in box coordinates. 2. The interference minimax box corresponding to the interference area in the first minimax coordinate system, when the interference area is determined to exist in the first step, with respect to the interference area in the second minimax coordinate system. The second step of determining the presence or absence of interference between the first primary minimax box and the interference minimax box in the first minimax coordinate system. To check the interference between the shapes of each other.