JP2000011210A - Device and method for generating curved surface and recording medium having recorded curved surface generating program thereon - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curved surface generating device that generates a curved surface section curve of which is transformed and moved along an orbital curve, is smoothly linked to a supporting curved surface and passes on the supporting curve. SOLUTION: A section curve coordinate system decision part 7 decides a section curve coordinate system so that a point on section curve to cross an orbital curve is made to be an origin, a direction towards a point on the section curve to cross a supporting curve from the origin is made to be an X axis, a tangential direction of the section curve at the origin is made to be a Y axis, a direction vertical to the X axis and the Y axis is made to be a Z axis, and the distance from the origin to a point on the section curve to cross the supporting curve is one. A section curve transformation moving part 9 generates a curved surface by transformation moving the section curve so that the origin of the section curve coordinate system is positioned on the orbital curve, the Y axis of the section curve coordinate system contacts the supporting curve on the orbital curve and a point in the distance 1 in the X axis direction from the origin of the section curve coordinate system is positioned on the supporting curve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curved surface creating apparatus and method, and a recording medium on which a curved surface creating program is recorded. More particularly, an apparatus, method and recording for creating a curved surface by moving a sectional curve along a trajectory curve by a computer. Regarding the medium. Further, the present invention provides a CAD / CAD system for supporting, for example, design design and mold design.
It can be applied to CAM systems.

[0002]

2. Description of the Related Art Conventionally, the following are known as this kind of curved surface creating apparatus or curved surface creating method.

Referring to FIG. 6, a curved surface shape generating apparatus for generating a curved surface by moving along a trajectory curve while rotating, enlarging, or reducing the cross-sectional curve using a previously generated cross-sectional curve and trajectory curve. Is disclosed in JP-A-5-250444.

Referring to FIG. 7, a cross-sectional curve is rotated, enlarged, and reduced so as to pass through the orbit curve and the support curve by using the pre-generated cross-section curve, orbit curve and support curve, and along the orbit curve. A curved surface generation method for generating a curved surface by moving is disclosed in Japanese Patent Laid-Open No. 6-168302.

Referring to FIG. 8, a cross-sectional curve is rotated using a cross-section curve, a trajectory curve, and a support surface generated in advance so as to pass through the trajectory curve and smoothly connect to the support surface on the trajectory curve. A curved surface generation method of generating a curved surface by moving along a trajectory curve while enlarging or reducing the size is known.

Specifically, in the apparatus for creating a curved surface shown in FIG. 6, (1) First, a point to be located on a trajectory curve in a space in which a cross-section curve is created is defined as an origin P0, and the cross-section curve is defined as a trajectory. A vector that is desired to be kept perpendicular to a cross-section that is a reference when the curve is taken is defined as a Z-axis, a vector that is desired to be constantly maintained upward in a direction perpendicular to the Z-axis is defined as a Y-axis, and a vector that is perpendicular to the Z-axis and the Y-axis is defined as (2) Next, at a plurality of positions on the trajectory curve, a point on the trajectory curve is defined as an origin Q0, and a tangent vector of the trajectory curve at the origin Q0 is defined as a Z-axis. A vector obtained by passing a predetermined upward vector through the origin Q0 and projecting on a plane perpendicular to the Z axis (hereinafter referred to as a cross section) is defined as the Y axis, and a vector perpendicular to the Z axis and the Y axis is defined as the X axis. Determine the cross-sectional coordinate system and (3 Further, the section curve is arranged in the space of the trajectory curve by rotating and moving the section curve coordinate system so as to match each section coordinate system. (4) Finally, the curved surface passing through the plurality of arranged section curves is set. By creating, the curved surface which rotated and moved the cross-sectional curve along the orbit curve was created.

As another method for determining the Z axis of the sectional coordinate system, a method is used in which the same vector given in advance at any position of the trajectory curve is used as the Z axis, or a section defining curve different from the trajectory curve. And a method has been used in which a tangent vector at a point associated with a point on the trajectory curve on the section defining curve is set as the Z axis.

Further, a method has been used in which the enlargement / reduction ratio at a point on the trajectory curve is obtained by using the enlargement / reduction ratio curve, and the enlargement / reduction is performed in addition to the rotation and movement when arranging the sectional curve. .

By using the above method, the sectional curve can be rotated,
It was possible to create a curved surface that moved along the orbit curve while enlarging and reducing.

A method of creating a curved surface as shown in FIG.
Is similar to the method of creating a curved surface such as The differences are the method of determining the X-axis and Y-axis and the method of determining the enlargement / reduction ratio of the sectional coordinate system at a plurality of positions on the sectional curve coordinate system and the orbit curve. That is, in the method of FIG.
(1) The X axis of the sectional curve coordinate system is a vector perpendicular to the Z axis and directed from the origin P0 to the point to be located on the support curve. (2) The Y axis of the sectional curve coordinate system is the Z axis and the X axis.
(3) The X axis of the sectional coordinate system is a vector perpendicular to the Z axis and directed from the origin Q0 to the intersection of the support curve and the section at that point, and (4) the Y axis of the sectional coordinate system. The axis is a vector perpendicular to the Z axis and the X axis. (5) The enlargement / reduction ratio is the distance from the origin P0 in the sectional curve coordinate system to the point to be located on the support curve;
It is determined to be the ratio of the distance from the origin Q0 in the sectional coordinate system to the intersection of the section and the support curve at that point.

According to this method, the points to be located on the orbital curve and the points to be located on the support curve are taken on the cross-sectional curve, so that the cross-sectional curve is rotated, enlarged, and reduced along the orbital curve. With the moved surface, a surface passing through the trajectory curve and the support curve could be created.

Similarly, the method of creating a curved surface as shown in FIG. 8 is different from the method of creating a curved surface as shown in FIG. 6 in that the Y of the sectional coordinate system and the sectional coordinate system at a plurality of positions on the trajectory curve are different. Only the method of determining the axis is different. That is, in the method of FIG. 8, (1) the Y axis of the sectional curve coordinate system is a vector that is perpendicular to the Z axis and is to be matched with the normal vector of the supporting curved surface, and (2) the Y axis of the sectional coordinate system is the origin. The normal vector of the support curved surface in Q0 is determined to be a vector projected on the cross section.

According to this method, a point to be located on the trajectory curve is set on the cross-sectional curve, and a vector perpendicular to a tangent vector of the cross-sectional curve at that point is defined as Y in the cross-sectional curve coordinate system.
By using an axis, a curved surface that moves along the trajectory curve while rotating, enlarging, or reducing the cross-sectional curve can create a curved surface that passes through the trajectory curve and smoothly connects to the support surface on the trajectory curve. Was.

[0014]

However, according to the above-described conventional surface forming apparatus or method, only the rotation, enlargement, and reduction are performed when moving the cross-sectional curve along the trajectory curve. 9 (a), the cross-sectional curve is deformed and moved along the orbit curve using the cross-sectional curve B, the orbit curve G, the support curved surface S, and the support curve C. Thus, a curved surface (R in FIG. 9B) passing through the support curve C could not be created.

That is, the curved surface created by the method for creating a curved surface as shown in FIG. 7 passes on the trajectory curve and the support curve, but does not smoothly connect to the support curved surface.

The curved surface created by the method for creating a curved surface as shown in FIG. 8 passes on the trajectory curve and smoothly connects to the support curved surface on the trajectory curve, but does not pass on the support curve.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem. When a cross-sectional curve is moved along a trajectory curve, the cross-sectional curve is deformed in addition to rotation, enlargement, and reduction, thereby providing a trajectory. It is an object of the present invention to provide a curved surface creating apparatus that smoothly connects to a support curved surface on a curve and generates a curved surface passing on the support curve.

[0018]

According to one aspect of the present invention to achieve the above object, a curve creating device includes a section curve creating means for creating a sectional curve for controlling a sectional shape of a curved surface to be created; A trajectory curve creating means for creating a trajectory curve for causing a cross-sectional curve to be deformed and moved, and a cross-section rule for creating a cross-section defined curve for determining a slope of a cross-section serving as a reference when the cross-sectional curve is deformed and moved Curve creation means, support curve creation means for creating a support curve through which the created surface should pass, support surface creation means for creating a support surface on which the created surface should smoothly connect on the trajectory curve, and intersection with the trajectory curve The point on the section curve to be taken is the origin,
The direction from the origin to the point on the cross-sectional curve that should intersect with the support curve is defined as the X axis, and the tangential direction of the cross-sectional curve at the origin is defined as Y.
A sectional curve coordinate system that determines a sectional curve coordinate system such that a direction perpendicular to the X axis and the Y axis is a Z axis, and a distance from the origin to a point on the sectional curve that should intersect with the support curve is 1. Determining means, the origin of the sectional curve coordinate system determined by the sectional curve coordinate system determining means is located on the trajectory curve, the Y axis of the sectional curve coordinate system is in contact with the supporting curved surface on the trajectory curve, A section curve deformation moving means for deforming and moving the section curve such that a point located at a distance of 1 in the X-axis direction from the origin is located on the support curve.

According to the present invention, the origin of the sectional curve coordinate system is located on the trajectory curve, the Y axis of the sectional curve coordinate system is in contact with the supporting curved surface on the trajectory curve, and the origin of the sectional curve coordinate system is in the X-axis direction. The sectional curve can be deformed and moved so that the point at a distance of 1 is located on the support curve.

Preferably, the section curve deformation moving means sets the point on the trajectory curve as the origin, sets a tangent vector at a point associated with the origin on the section defining curve as the Z axis, and passes the Z axis from the origin through the origin. The direction toward the intersection of the section and the support curve as a normal vector is defined as the X axis, the intersection of the tangent plane of the support curved surface at the origin and the section is defined as the Y axis, and the cross section and the support curve are defined from the origin. A sectional coordinate system determining means for determining a sectional coordinate system so that the distance to the intersection is set to 1;
Point sequence coordinate conversion means for converting a point sequence on the cross-sectional curve from the cross-section curve coordinate system determined by the cross-section curve coordinate system determination means to the cross-sectional coordinate system determined by the cross-section coordinate system determination means.

According to another aspect of the present invention, a curved surface creating method includes a step of creating a sectional curve for controlling a sectional shape of a curved surface to be created, and a step of forming a trajectory curve for causing the sectional curve to be deformed and moved. A step of creating, a step of creating a section defining curve for determining a slope of a section which is a reference when deforming and moving the section curve, and a step of creating a support curve through which a created surface passes. A step of creating a support surface to be smoothly connected to the orbit curve on the cross-section curve, and a direction from the origin to a point on the cross-section curve to intersect with the support curve from the origin as a point on the cross-section curve to intersect with the orbit curve Is the X axis, the tangential direction of the sectional curve at the origin is the Y axis, and the X axis and the Y
Determining a cross-sectional coordinate system such that the direction perpendicular to the axis is the Z-axis, and the distance from the origin to a point on the cross-sectional curve that should intersect with the support curve is 1, and determining the cross-sectional curve coordinate system The origin of the sectional curve coordinate system determined by the above is located on the orbital curve, the Y axis of the sectional curve coordinate system is in contact with the support curved surface on the orbital curve, and one point in the X-axis direction from the origin of the sectional curve coordinate system. Deforming and moving the sectional curve so that a point at a distance is located on the support curve.

According to still another aspect of the present invention, in a recording medium storing a curved surface creating program for creating a curved surface by a computer, the curved surface creating program causes the computer to control a cross-sectional shape of the created curved surface. Create a curve, create a trajectory curve to follow the cross-sectional curve when deforming and moving it, and create and create a cross-section defining curve to determine the reference cross-sectional inclination when deforming and moving the cross-sectional curve A curved surface to be passed is created, and a curved surface to be created is created.A curved surface to be created is made to be smoothly connected on the trajectory curve. The direction toward the point on the cross-sectional curve that should intersect with the X-axis is defined as the X-axis, the tangential direction of the cross-sectional curve at the origin is defined as the Y-axis,
The direction perpendicular to the axis and the Y axis is the Z axis, and the distance from the origin to a point on the cross-sectional curve that should intersect with the support curve is 1
The origin of the previously determined cross-sectional curve coordinate system is located on the trajectory curve, the Y-axis of the cross-sectional curve coordinate system is in contact with the supporting curved surface on the trajectory curve, The cross-sectional curve is deformed so that a point located at a distance of 1 in the X-axis direction from the origin of the curved coordinate system is located on the support curve.

[0023]

FIG. 1 is a block diagram showing a configuration of a curved surface creating apparatus according to one embodiment of the present invention.
Referring to the figure, the curved surface creation device includes a curved / curved surface display unit 1.
A section curve creating section 2, a trajectory curve creating section 3, a section defining curve creating section 4, a support curve creating section 5, a support curved surface creating section 6, a section curve coordinate system determining section 7, and an initial section determining. Part 8
A section curve deformation moving section 9 and a section interpolation curved surface creating section 10
A section adding unit 11, a control unit 12 for controlling the portions indicated by the reference numerals 1 to 11, and a storage unit 13 for storing curves, curved surfaces, and the like created by the portions indicated by the reference numerals 1 to 11. And The curved surface creation device creates a curved surface while synchronizing with the input device 30 such as a keyboard and a mouse and the display device 31. Further, a program for the control may be stored in the floppy disk 34 or the CD-ROM 35 and input to the device via the external storage device 33.

The section curve deformation moving section 9 includes a section coordinate system determining section 20, an initial point sequence determining section 21, a point sequence coordinate converting section 22, a point sequence interpolation curve creating section 23, and a point sequence adding section. 24
And a deformation movement control unit 25 for controlling the parts indicated by reference numerals 20 to 24.

FIG. 2 is a flowchart showing the flow of the process of the curved surface creating apparatus. Hereinafter, the operation of the curved surface creating apparatus shown in FIG. 1 will be described by taking as an example a case where the curved surface shown in FIG. 9B is created.

(Step S1) The section curve creating section 2 receives a command from the control section 12, creates a section curve B using data input from the input device 30, and stores the section curve B in the storage section 13.
To be stored. Thereafter, the curve / curved surface display unit 1 receives a command from the control unit 12 and displays the cross-sectional curve B on the display device 31.

The sectional curve B may be any curve as long as it is a parametric curve that can be expressed by P = f (t) (Equation 1).

In Equation 1, P is a position vector in a three-dimensional space, t is a parameter of a curve, and f is a vector function of the curve.

The method of creating the parametric curve is described in "Shape Processing Engineering by Computer Display [II] (by Fujio Yamaguchi, Nikkan Kogyo Shimbun)" Curvature is 0
There are well known methods of generating a B-spline as follows, and methods of generating a NURBS from a plurality of smoothly connected straight lines and arcs.

(Step S 2) The trajectory curve generator 3 receives a command from the controller 12, generates a trajectory curve G using data input from the input device 30, and
To be stored. Thereafter, the curve / curved surface display unit 1 receives a command from the control unit 12 and displays the trajectory curve G on the display device 31. The orbit curve may be any curve as long as it is a parametric curve.

(Step S 3) The section defining curve creating section 4 receives a command from the control section 12, creates a section defining curve using the data input from the input device 30, and stores the section defining curve in the storage section 13. Thereafter, the curve / curved surface display unit 1 receives a command from the control unit 12 and displays the section defining curve on the display device 31.

The section defining curve is a curve for defining a section which serves as a reference when the section curve is deformed and moved. When the section defining curve is a curve having the same shape as the orbit curve, the section is defined as an orbit curve. Always kept vertical.

When the section defining curve is a straight line, the section always has a constant slope. If the section definition curve is any other curve,
The cross section is constantly kept perpendicular to the curve.

The section defining curve creating section 4 creates a section defining curve which is a parametric curve which can be expressed by Equation 1, and which has the same parameter range as that of the trajectory curve G. By doing so, it is possible to simplify the processing of the subsequent steps. That is, the orbit curve G
The cross section passing through the arbitrary point P above is obtained as a plane passing through the point P and perpendicular to the tangent vector of the section defining curve at the parameter t, where t is the parameter of the trajectory curve G at the point P.

In the following steps, the operation will be described on the assumption that the section defining curve is a curve having the same shape as the trajectory curve.

(Step S 4) The support curve creation unit 5 receives a command from the control unit 12, creates a support curve C using data input from the input device 30, and stores the support curve C in the storage unit 13.
To be stored. Thereafter, the curve / curved surface display unit 1 receives a command from the control unit 12 and displays the support curve C on the display device 31.

The support curve C does not need to be a parametric curve as long as it can calculate an intersection with a plane, and may be a curve composed of a plurality of smoothly connected curves.

However, the curve must intersect all the sections on the orbit curve G only once.

(Step S 5) The support surface creating unit 6 receives a command from the control unit 12, creates a support surface S using data input from the input device 30, and stores the support surface S in the storage unit 13.
To be stored. Thereafter, the curve / curved surface display unit 1 receives a command from the control unit 12 and displays the support curved surface S on the display device 31.

The support surface S does not need to be a parametric surface as long as the surface can calculate a normal vector at a specified point, and may be a surface composed of a plurality of smoothly connected surfaces. However, the curved surface must pass through the orbit curve G only once.

(Step S6) Section Curve Coordinate System Determination Unit 7
Receives the command from the control unit 12, refers to the cross-sectional curve B stored in the storage unit 13, and uses the input device 30 to intersect the point P0 on the cross-sectional curve to cross the orbit curve and the support curve. A point P1 on the power section curve is input, P0 (origin of the section curve coordinate system), a unit vector Vx (X-axis of the section curve coordinate system) from P0 to P1, and a unit vector Vy of a tangent vector of the section curve at P0. (The Y axis of the sectional curve coordinate system), the unit vector Vz perpendicular to both Vx and Vy (the Z axis of the sectional curve coordinate system), and the distance D from P0 to P1 (the enlargement / reduction ratio of the sectional curve coordinate system). It is stored in the storage unit 13 (see FIG. 4).

(Step S7) The initial section determining unit 8 receives an instruction from the control unit 12, refers to the trajectory curve G stored in the storage unit 13, and sets several parameters including the start point and end point parameters of the trajectory curve G. The parameters are entered in the trajectory curve parameter list and stored in the storage unit 13.

The parameters to be included in the trajectory curve parameter list are determined by inserting parameters obtained by equally dividing the start and end point parameters of the trajectory curve G into a predetermined number, or by setting the parameter interval according to the curvature of the trajectory curve G. There are ways to change.

(Step S8) The section curve deformation moving unit 9 receives a command from the control unit 12, and receives the section curve B, the trajectory curve G, the section defining curve, the support curve C, and the support curved surface S stored in the storage unit 13. The cross section curve is deformed and moved to the parameter position extracted from the trajectory curve parameter list while referring to the cross section curve coordinate system, and the cross section curve after the deformation movement is stored in the storage section 13 together with the parameters.

The cross-sectional curves after the deformation movement are stored while being ordered so that the parameters are arranged in ascending order.

In this manner, a process of creating a curved surface interpolating the cross-sectional curve after the deformation movement (step S10)
Can be simplified. The details of the deformation moving method will be described later.

(Step S 9) The control unit 12 checks the storage unit 1
Referring to the number of parameters included in the orbit curve parameter list of No. 3, if there is one or more, step S8 is repeated.

(Step S10) When there are no more parameters in the trajectory curve parameter list, the section interpolation curved surface creating section 10 receives a command from the control section 12, and receives the deformed and moved section stored in the storage section 13. A cross-section interpolation curved surface that smoothly passes through the curve is created and stored in the storage unit 13.

As a method of creating a curved surface that smoothly passes through the cross-sectional curve after the deformation movement, a method using spline interpolation or the like is known.

(Step S11) Upon receiving a command from the control section 12, the section adding section 11 receives the section interpolated curved surface stored in the storage section 13 and the section curve after the deformation movement, the section curve B, the trajectory curve G, and the section. With reference to the prescribed curve, the support curve C, the support curved surface S, and the cross-sectional curve coordinate system, the cross-sectional curve is newly deformed and moved to the midpoint of each section surrounded by the two deformed and moved cross-sectional curves. If the cross-section interpolation surface does not match,
The midpoint parameter is added to the trajectory curve parameter list.

In the determination as to whether the newly deformed and moved curve and the cross-section interpolated surface coincide, if both of the following two types of determinations (1) and (2) are true,
Assumes a match.

(1) The shortest distance between each of the plurality of error determination points set on the newly deformed and moved curve and the cross-section interpolation curved surface is within a predetermined allowable value.

As the error judgment point, there are a method using points obtained by equally dividing the start and end point parameters of the curve into a predetermined number, and a method of changing the interval between the points according to the curvature of the curve. .

(2) The inner product of the tangent vector at the origin of the cross-section coordinate system of the newly deformed and moved curve and the normal vector at the origin of the cross-section interpolated curved surface is within a predetermined allowable value.

(Step S12) The control unit 12 refers to the number of parameters included in the trajectory curve parameter list of the storage unit 13, and if there is one or more, the control unit 12 performs steps S8 to S11.
Is repeated.

(Step S13) If there are no more parameters in the trajectory curve parameter list,
The curved surface display unit 1 receives a command from the control unit 12 and receives a command from the storage unit 1.
3 is displayed on the display device 31.

By the above processing, the curved surface obtained by deforming and moving the sectional curve along the trajectory curve,
And a curved surface R passing on the support curve C can be generated.

Next, the operation of the section curve deformation moving section 9 will be described in detail. The section curve deformation moving section 9 is configured such that the origin of the section curve coordinate system determined by the section curve coordinate system determination section 7 is located on the trajectory curve, and the Y axis of the section curve coordinate system contacts the support curved surface on the trajectory curve. The sectional curve is deformed so that a point located at a distance of 1 in the X-axis direction from the origin of the sectional curve coordinate system is located on the support curve.

FIG. 3 is a flowchart showing the operation of the section curve deformation moving unit. (Step S21) The section coordinate system determination unit 20 receives an instruction from the deformation movement control unit 25, extracts one parameter from the trajectory curve parameter list stored in the storage unit 13, and obtains the parameter position on the trajectory curve G. The point Q at
0 (origin of the sectional coordinate system) and a unit vector Wz (Z-axis of the sectional coordinate system) of the tangent vector at the parameter position on the sectional defining curve are obtained and stored in the storage unit 13. Next, an intersection Q1 between the plane passing through the point Q0 and having the normal vector Wz as the normal vector and the support curve C is determined, and a unit vector Wx (X-axis of the sectional coordinate system) from the point Q0 to the point Q1 and the point Q0
Is stored in the storage unit 13 from the distance E to the point Q1 (enlargement / reduction ratio of the sectional coordinate system). Further, a unit vector Wy (Y-axis of the sectional coordinate system) in the cross product direction of the normal vector N and the vector Wz of the support curved surface S at the point Q0 is obtained, and the storage unit 1
3 (see FIG. 5).

(Step S22) Initial point sequence determination unit 21
Receives a command from the deformation movement control unit 25 and
, The parameters of the cross-sectional curve B at the start and end points of the cross-sectional curve, the point P0 on the cross-sectional curve to intersect with the trajectory curve, and the point P1 on the cross-sectional curve to intersect with the support curve. The parameters of several points including the parameters are put in the section curve parameter list and stored in the storage unit 13.

The method for determining the parameters to be included in the section curve parameter list is the same as in step S7, except that the section curve B
And a method of changing the parameter interval in consideration of the curvature of the cross-sectional curve B.

(Step S23) Point sequence coordinate converter 22
Receives a command from the deformation movement control unit 25 and
The point P on the sectional curve B is obtained from the sectional curve B stored in
Ask for. This is converted to a point Q by the following equation 2 and stored in the storage unit 13 together with the parameters.

The points Q after the coordinate conversion are stored while being ordered so that the parameters are arranged in ascending order. By doing so, the process of creating a curve interpolating the point Q (step S25) can be simplified.

Q = aEWx + bEWy + cEWz + Q0 a = (A−KB) / (1−K ² ) b = (B−KA) / (1−K ² ) c = CA = (P−P0) · Vx / DB (P−P0) · Vy / DC = (P−P0) · Vz / DK K = Vx · Vy (Equation 2) where P0, Vx, Vy, Vz, and D are the origins of the sectional curve coordinate system, respectively. , X-direction unit vector, Y-direction unit vector, Z-direction unit vector, and enlargement / reduction ratio. Q0,
Wx, Wy, Wz and E are the origin of the sectional coordinate system, X
The direction unit vector, the Y direction unit vector, the Z direction unit vector, and the enlargement / reduction ratio. The operator “·” means an inner product operation of a vector.

(Step S24) Deformation movement control unit 25
Refers to the number of parameters in the section curve parameter list in the storage unit 13, and if there is one or more, step S2
Repeat 3.

(Step S25) When there are no more parameters in the section curve parameter list, the point sequence interpolation curve generator 23 receives a command from the deformation movement controller 25 and receives the coordinates stored in the memory 13. A point sequence interpolation curve that smoothly passes through the converted point sequence and has the Y direction vector as a tangent vector at the origin of the sectional coordinate system is created, and stored in the storage unit 13.
To be stored.

As a method of creating a curve that smoothly passes through a point sequence, a method using spline interpolation is known.

(Step S 26) The point sequence adding section 24 receives the command from the deformation movement control section 25, and refers to the sectional curve B, the sectional curve coordinate system, and the sectional coordinate system, and performs coordinate conversion.
When a new point on the cross-sectional curve B is coordinate-transformed to a midpoint of each section surrounded by the points, and the shortest distance between the point and the point sequence interpolation curve exceeds a predetermined allowable value, the midpoint parameter Is added to the section curve parameter list.

(Step S27) Deformation movement control unit 25
Refers to the number of parameters in the section curve parameter list in the storage unit 13, and if there is one or more, step S2
Steps S26 to S26 are repeated.

The above steps S21 to S27 are the processing procedure of the section curve deformation moving unit 9. As described above, according to the curved surface creating apparatus in the present embodiment, a curved surface in which a cross-sectional curve is deformed and moved along a trajectory curve is smoothly connected to a supporting curved surface on the trajectory curve and generates a curved surface passing through the supporting curve. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a curved surface creation device according to one embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of a process performed by the curved surface creation device of FIG. 1;

FIG. 3 is a flowchart illustrating an operation of a section curve deformation moving unit;

FIG. 4 is a diagram illustrating the operation of a section curve coordinate system determination unit.

FIG. 5 is a diagram illustrating an operation of a cross-section coordinate system determination unit.

FIG. 6 is a first diagram showing an example of a curved surface created by a conventional curved surface creating device and a curved surface creating method.

FIG. 7 is a second diagram showing an example of a curved surface created by a conventional curved surface creating device and a curved surface creating method.

FIG. 8 is a third diagram showing an example of a curved surface created by a conventional curved surface creating device and a curved surface creating method.

FIG. 9 is a diagram illustrating a specific example of a curved surface created by the curved surface creating device.

[Explanation of symbols]

 Reference Signs List 4 Section defining curve creating section 5 Support curve creating section 6 Supporting curve creating section 7 Section curve coordinate system determining section 9 Section curve deformation moving section 20 Section coordinate system determining section 22 Point sequence coordinate converting section 33 External storage device 34 Floppy disk 35 CD -ROM B Cross section curve G Orbit curve S Support curved surface C Support curve P0 Origin of cross section curve coordinate system Vx X direction unit vector of cross section curve coordinate system Vy Y direction unit vector of cross section curve coordinate system Vz Z direction unit of cross section curve coordinate system Vector D Enlargement / reduction ratio of cross-sectional coordinate system Q0 Origin of cross-sectional coordinate system Wx X-direction unit vector of cross-sectional coordinate system Wy Y-direction unit vector of cross-sectional coordinate system Wz Z-direction unit vector of cross-sectional coordinate system E Enlargement / reduction of cross-sectional coordinate system rate

Claims (4)

[Claims] 1. A curved surface creating apparatus for creating a curved surface, comprising: a sectional curve creating means for creating a sectional curve for controlling a sectional shape of a curved surface to be created; A trajectory curve creating means for creating a trajectory curve, a section defining curve creating means for creating a section defining curve for determining a slope of a section to be a reference when deforming and moving the section curve, and a curved surface to be created should pass A support curve creating means for creating a support curve, a support surface creating means for creating a support surface on which a curved surface to be created should be smoothly connected on a trajectory curve, and a point on a cross-sectional curve which should intersect with the trajectory curve as an origin; The direction from the origin to a point on the cross-sectional curve that should intersect with the support curve is the X axis, the tangential direction of the cross-sectional curve at the origin is the Y axis, and the direction perpendicular to the X axis and the Y axis is Z.
A sectional curve coordinate system determining means for determining a sectional curve coordinate system so that a distance from the origin to a point on the sectional curve to intersect with the support curve is set to 1; The origin of the cross-sectional curve coordinate system is located on the trajectory curve, the Y-axis of the cross-sectional curve coordinate system is in contact with the supporting curved surface on the trajectory curve, and the distance from the origin of the cross-sectional curve coordinate system is 1 in the X-axis direction. A cross-section curve deformation moving means for deforming and moving the cross-section curve so that a certain point is located on the support curve. 2. The section curve deformation moving means has a point on an orbit curve as an origin, a tangent vector at a point on the section defining curve corresponding to the origin as a Z axis,
A direction from the origin to the intersection of the cross section with the Z axis as a normal vector and the support curve through the origin as the X axis,
A sectional coordinate system for determining a sectional coordinate system such that a line of intersection between the tangent plane of the support curved surface at the origin and the cross section is the Y axis, and a distance from the origin to the intersection of the cross section and the support curve is 1. Determining means; and a point sequence coordinate converting means for converting a point sequence on the sectional curve from the sectional curve coordinate system determined by the sectional curve coordinate system determining means to the sectional coordinate system determined by the sectional coordinate system determining means. The curved surface creation device according to claim 1, comprising: 3. A method for creating a curved surface, comprising the steps of: creating a cross-sectional curve for controlling a cross-sectional shape of a curved surface to be created; and generating a trajectory curve for causing the cross-sectional curve to follow a deformed movement. A step of creating a section defining curve for determining the slope of the section which is a reference when deforming and moving the section curve; a step of creating a support curve through which the created surface passes; Creating a support surface to be smoothly connected on the orbit curve; and setting a point on the cross-section curve to intersect with the orbit curve as an origin, and setting a direction from the origin to a point on the cross-section curve to intersect with the support curve as X. Axis, the tangential direction of the cross-sectional curve at the origin is the Y axis, and the direction perpendicular to the X axis and the Y axis is Z
Determining a sectional curve coordinate system so that the distance from the origin to a point on the sectional curve that should intersect with the support curve is set to 1; and a section determined by the step of determining the sectional curve coordinate system. The origin of the curved coordinate system is located on the orbit curve, and the Y axis of the cross-sectional curve coordinate system is in contact with the support curved surface on the orbit curve,
Deforming and moving the sectional curve so that a point located at a distance of 1 in the X-axis direction from the origin of the sectional curve coordinate system is located on the support curve. 4. A recording medium which records a curved surface creation program for creating a curved surface by a computer,
The curved surface creation program causes a computer to create a cross-sectional curve for controlling the cross-sectional shape of the curved surface to be created, to create a trajectory curve to follow the cross-sectional curve when deforming and moving, and to deform and move the cross-sectional curve. To create a cross-section defining curve to determine the slope of the reference cross-section, create a support curve through which the created surface should pass, and create a support surface through which the created surface should smoothly connect on the orbit curve, The point on the cross-sectional curve to intersect with the orbit curve is the origin, the direction from the origin to the point on the cross-sectional curve to intersect with the support curve is the X axis, the tangential direction of the cross-sectional curve at the origin is the Y axis, The direction perpendicular to the X axis and the Y axis is Z
Axis, the cross-sectional curve coordinate system is determined so that the distance from the origin to a point on the cross-sectional curve that should intersect with the support curve is set to 1, and the origin of the previously determined cross-sectional curve coordinate system is set on the trajectory curve. And the Y-axis of the sectional curve coordinate system is in contact with the support curved surface on the orbit curve, and the Y-axis of the sectional curve coordinate system is located at 1 point from the origin of the sectional curve coordinate system in the X-axis direction
Characterized in that the cross-sectional curve is deformed and moved so that a point at a distance of (c) is located on the support curve.