JP2002062127A - Three-dimensional measuring method for virtual ridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional measuring method wherein three- dimensional coordinate data on a virtual ridge as a nodal line crossed by extending curved surfaces sandwiching the corner part of an object, to be measured, such as a mold or the like is calculated with good operability and with high accuracy. SOLUTION: Two arbitrary gage heads 33a, 33b which are installed at a measuring-point indicating implement 30 are simultaneously brought into contact with the curved surfaces 3a, 3b on both sides sandwiching the corner part 2 of the object 1 to be measured. Respective three-dimensional coordinate data on the two gage heads 33a, 33b are calculated by a computer 50. On the basis of the calculated three-dimensional coordinate data and on the basis of CAD data on the object 1, to be measured, stored in the computer 50, the three- dimensional coordinate data on the virtual eidge 4 of the corner part 2 is calculated. The deviation amount of the virtual ridge 4 with reference to the CAD data is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting the three-dimensional coordinates of a virtual ridge line at a corner of a measurement object such as a mold and comparing and evaluating the detected three-dimensional coordinates with CAD data and the like. .

[0002]

2. Description of the Related Art In a manufacturing process of an object to be measured such as an automobile body or a mold, a computer is used to numerically calculate measurement data obtained by measuring the external dimensions of the object with a three-dimensional measuring device such as a CCD camera. There is a step of evaluating dimensional accuracy and the like of the measurement target by comparing and evaluating the CAD data of the target. For example, measurement data obtained by measuring a virtual ridgeline of a corner portion of a measurement object with a three-dimensional measuring device and ridgeline data of CAD data are compared and evaluated, and the dimensional accuracy of the corner portion of the measurement object is determined based on the CAD data. There is a process to evaluate.

FIG. 5 shows a corner portion 2 of an object 1 to be measured. A first curved surface 3a and a second curved surface 3b are adjacent to each other with the corner portion 2 interposed therebetween, and both curved surfaces 3a and 3b are shown by broken lines in FIG. The intersection line (the chain line in FIG. 5) where the extension surfaces intersect is the virtual ridge line 4,
By calculating the three-dimensional coordinate data of the virtual ridge line 4, the dimensional accuracy and the like of the corner 2 are evaluated. First curved surface 3
a and the second curved surface 3b are curved surfaces including a flat surface. Virtual ridgeline 4
The calculation of the three-dimensional coordinate data is performed in the manner shown in FIG. 6 or FIG.

FIG. 6 shows a virtual ridge line 4 made of clay 10. Clay 10 is placed in a chevron cross section on corner 2 of measurement object 1, and both curved surfaces of clay 10 are extended surfaces of first curved surface 3 a and second curved surface 3 b, and ridge 11 of clay 10 is formed.
Coincides with the virtual ridge line 4. This clay 10
A portable measuring point indicator, for example, a probe 21 at the tip of a measuring tool 20 is brought into contact with the ridgeline 11 of the measuring tool 20, and the three-dimensional coordinates of a plurality of fixed points (light emitting points) provided on the upper part of the measuring tool 20 are converted into optical three-dimensional coordinates. The three-dimensional coordinate data of an arbitrary point on the ridgeline 11 is obtained by measuring with a measuring device and numerically calculating with a computer of the measuring device. Similarly, three-dimensional coordinate data of a plurality of points on the ridgeline 11 is obtained, and the coordinate data is numerically calculated to calculate three-dimensional coordinate data of the virtual ridgeline 4 of the measurement target 1. The calculated coordinate data is compared with the ridge line data of the CAD data stored in advance in the computer, and the dimensional accuracy and the like of the corner 2 of the measurement object 1 and the two curved surfaces 3a and 3b are evaluated. Is done.

FIG. 7 shows two points A ₁ , A ₂ , B ₁ , and B ₂ separated from each other on the curved surfaces 3a, 3b when the first curved surface 3a and the second curved surface 3b are substantially flat. And the points A ₁ , A ₂ , B ₁ , and B ₂ are sequentially applied to the probe 21 of the same measurement tool as described above, so that each point A ₁ , A ₂
The three-dimensional coordinate data of A ₂ , B ₁ , and B ₂ are obtained, the straight line of the first curved surface 3a is defined from the coordinate data of the two points A ₁ and A ₂ of the first curved surface 3a, and the two points of the second curved surface 3b are defined. A straight line of the second curved surface 3b is defined from the coordinate data of B ₁ and B ₂ and these defined 2
The coordinates of the intersection of the straight lines are set as the coordinate data of one point on the virtual ridgeline 4. In this way, coordinate data of a plurality of points of the virtual ridge line 4 is obtained, three-dimensional coordinate data of the virtual ridge line 4 of the measurement target 1 is calculated, and this is stored in a CAD stored in a computer in advance.
The dimensional accuracy and the like of the measuring object 1 are evaluated by comparing and evaluating the ridge line data of the data.

When the first curved surface 3a and the second curved surface 3b are convex surfaces which are not flat, the sampling points of the two curved surfaces 3a and 3b are set to three or more points, and the position coordinates of these many sampling points are set. From the data, both surfaces 3a,
The curve 3b is defined, and the three-dimensional coordinate data of the virtual ridgeline 4 is calculated from the position coordinates of the intersection of the defined two curves.

[0007]

In the three-dimensional measuring method of the virtual ridgeline using clay shown in FIG. 6, the work of accurately placing the clay on the object to be measured and the work of removing the clay require many man-hours, resulting in poor workability. . Also, the measurement accuracy of the virtual ridgeline is affected by the skill of the worker who puts up the clay, and the measurement accuracy is not stable. Furthermore, depending on the size and shape of the measurement object, it is often difficult to place clay on the corner portion, which is the portion where the virtual ridgeline is measured, and lacks flexibility and versatility. In addition, if a measuring element is applied to the viscosity, the viscosity portion may be deformed, and accurate measurement may not be performed.

[0008] The three-dimensional measuring method of the virtual ridge line shown in FIG.
If two or more sampling points can be set on both curved surfaces sandwiching the corner portion of the measurement object, highly accurate three-dimensional measurement can be performed, and this type of measurement method can be applied to measurement objects having various dimensions and shapes. However, in order to set two or more points on each of the two curved surfaces sandwiching the corner of the object to be measured as sampling points, manually move a measuring tool or the like to each sampled point, and measure each sampling point in order, The number of man-hours for three-dimensional measurement of one virtual ridgeline increases, and it is difficult to improve workability.

An object of the present invention is to provide a three-dimensional measuring method for calculating three-dimensional coordinate data of virtual ridge lines of both curved surfaces sandwiching a corner portion of an object to be measured with reduced man-hour and good workability.

[0010]

According to a first aspect of the present invention, there is provided a three-dimensional measuring method for a virtual ridgeline, wherein the first curved surface and the first curved surface adjacent to each other with a corner portion of the object to be measured interposed therebetween are provided. Two tracing styluses placed apart from the tip of the measuring point indicator are simultaneously brought into contact with each of the two curved surfaces, and the three-dimensional coordinate data of each tracing stylus is calculated and sampled by a computer, and the obtained stylus is obtained. On the virtual ridge line, which is a virtual intersection of the first curved surface and the second curved surface extended to the corner side, based on the three-dimensional coordinate data of the above and the CAD data of the measurement object stored in advance in the computer. It is characterized in that coordinate data of a point is calculated.

According to a third aspect of the present invention, in the three-dimensional measuring method of the virtual ridgeline according to the first aspect, the sampling measurement operation is performed in the direction of a corner part by a measuring point indicator. Is performed at a plurality of sampling points by relative movement, and based on three-dimensional coordinate data of the tracing stylus obtained from the plurality of sampling points and CAD data of the measurement object stored in the computer in advance, the first curved surface and the It is characterized in that coordinate data of a virtual ridgeline which is a virtual intersection line of the extended surface obtained by extending the two curved surfaces to the corner portion side is calculated.

According to a third aspect of the present invention, in the method of measuring a virtual ridgeline according to the first or second aspect, the three-dimensional coordinate data of the two tracing styluses is measured. It is characterized in that the amount of deviation from the CAD data of the virtual ridge line is calculated by comparing and evaluating the CAD data of the object.

Here, the CAD data is three-dimensional coordinate data of a corner portion and both curved surfaces in a design stage of a measurement object to be manufactured, and the present invention utilizes the CAD data to calculate the measurement object. The coordinate data of the virtual ridgeline is accurate,
Easy to get. Also, by calculating the amount of deviation of the coordinate data of the two tracing styluses from the CAD data, the dimensional accuracy of the measuring object in the manufacturing stage is evaluated with high reliability.

According to a third aspect of the present invention, in the three-dimensional measuring method of the virtual ridgeline according to the first or second aspect, three or more of the measuring point indicating tools are provided at the tip of the measuring point indicator. The present invention is characterized in that the tracing styluses are set apart from each other, and two tracing styluses suitable for the shape of the corner of the object to be measured are selected and used.

Here, as the measuring point indicator, a portable measuring tool having two or more measuring elements at the tip may be used.
Such a measuring point indicator is an optical measuring tool in which three or more light emitting points installed on an upper part are read by a computer of a remote optical three-dimensional measuring device (CCD camera or the like), an articulated arm, or the like. The measuring tool attached to the mechanical three-dimensional measuring device having the following is applied. Further, two or more tracing styluses are desirably spheres having the same radius, but their shapes and sizes are not limited.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A virtual ridge 4 of a measurement object 1 shown in FIG.
An embodiment of the measurement according to the method of the present invention will be described with reference to FIGS.

The measuring point indicating tool 30 shown in FIG. 1 is a portable optical measuring tool operated with one hand, and has two or more measuring elements 33a at the tip. The measuring point indicator 30 has a main body 31 held by one hand and a probe 32 protruding from a lower end of the main body 31. Light emitting points 34, such as light emitting diodes, are provided at a plurality of fixed locations. Probe part 3
The two tips are branched into a plurality of pieces, and the probes 33a,... Are connected one by one to each of the branched tips. FIG. 4 shows a specific example of the measuring point indicating tool 30. The measuring point indicating tool 30 shown in FIG. For example, a sphere (a stylus sphere) having the same radius. When measuring the virtual ridgeline 4 of the measuring object 1 with the measuring point indicator 30, any two of the five tracing styluses 33a to 33e are selected and used as shown in FIG. Note that FIG. 1 shows only two tracing styluses used, and these two are, for example, a first tracing stylus 33a and a second tracing stylus 33b.

The virtual ridge 4 of the corner 2 of the object 1 to be measured
At the time of measurement, the five measuring elements 33 of the measuring point indicator 30
a that most closely matches the size and shape of the corner portion 2 out of a to 33e
Are selected, and the selected two first tracing stylus 33a and second tracing stylus 33b are connected to the first curved surface 3a on both sides of the corner portion 2.
And one sampling point of the second curved surface 3b at the same time, and the main body 3 of the measuring point indicator 30 at this time.
1 is imaged by an imaging device 40 such as a plurality of CCD cameras, and the imaged image data is sent to a computer 50.

The computer 50 calculates three-dimensional coordinate data of a plurality of light-emitting points 34,... Of the main body 31, and calculates the center of the two first tracing stylus 33a and the second tracing stylus 33b based on the coordinate data. Calculate point coordinates. That is, as shown in FIG. 2, the sphere centers Pa and Pb of the two tracing styluses 33a and 33b simultaneously abutting on both the curved surfaces 3a and 3b of the measuring object 1,
The distance between the light emitting points 34,... At the fixed point of the measuring point indicator 30 is stored in the computer 50 as known data, and the known data and the three-dimensional coordinate data of the light emitting points 34,. Spherical center P of measuring elements 33a and 33b
The three-dimensional coordinate data of a and Pb is calculated.

On the other hand, the computer 50 stores the surface data of the first CAD curved surface Ca, the second CAD curved surface Cb, and the CAD corner surface Cc of the CAD data indicated by the chain line in FIG. When the two tracing styluses 33a and 33b simultaneously come into contact with one sampling point of each of the two curved surfaces 3a and 3b of the measuring object 1, and the three-dimensional coordinate data of the respective sphere centers Pa and Pb is obtained, the sphere is obtained. Projection points Qa, Qb obtained by projecting the centers Pa, Pb on the corresponding CAD curved surfaces Ca, Cb from orthogonal directions.
Is calculated. Then, as shown in FIG. 3, two spherical centers Pa and Pb and two projected points Qa and Qb
A cut plane is defined from the four points. Center Pa of probe 33a
A point Ma at a position separated from the point Pa by the radius of the tracing stylus on the straight line connecting the point Pa and the projection point Qa is obtained, and the error (vector ea) on the curved surface 3a is calculated from Ma and Qa. Curved surface 3
An error (vector eb) is similarly calculated for b. Therefore, the error (vector e) from the CAD data of the virtual ridge line on the section plane is calculated by vector ea + vector eb, and the position coordinate data of one point is obtained.

The above two curved surfaces 3a, 3b sampling operation of the sampling points S ₁ in which a plurality of spaced measuring points the pointing device 30 so modeled after the direction of the corner portion 2 of FIG. 1,
S ₃ ,... Are sequentially performed to calculate three-dimensional coordinate data of the virtual ridge line 4. The amount of deviation between the curved surfaces is calculated based on the coordinate data of the two curved surfaces 3a and 3b of the measuring object 1 and the CAD data of the CAD curved surfaces Ca and Cb, and the CAD virtual ridgeline Cd where the extended surfaces of the two CAD curved surfaces Ca and Cb intersect is measured. From the coordinate data of the virtual ridge line 4 of the object 1, a deviation Dx between the two virtual ridge lines Cd and 4 is calculated. By evaluating the presence / absence and magnitude of such a shift amount, the corner portion 2 and both curved surfaces 3 of the measurement object 1 are evaluated.
The dimensional accuracy of a and 3b is evaluated with high accuracy.

The two tracing styluses 33a and 33b of the measuring point pointing device 30 used in the above-described virtual ridgeline measuring method include:
The spheres having different radii may be used. In addition, five tracing styluses 33a to 33e are installed on the measuring point indicator 30 with different intervals and directionality, and are most suitable for the size of the corner 2 of the measuring object 1 and the direction of the virtual ridgeline. If the number of tracing styluses is used, the manual tracing operation of the measuring point indicator 30 can always be performed under favorable conditions, and the workability of the three-dimensional measuring operation of the virtual ridgeline is further improved. In the above embodiment, the optical measuring point indicator 30 is used. However, this type of measuring point indicator can use a measuring point indicator attached to a mechanical three-dimensional measuring device. is there.

[0023]

According to the present invention, two tracing styluses of a measuring point indicator are simultaneously brought into contact with both curved surfaces sandwiching a corner portion of an object to be measured, and coordinate data of one sampling point of each of the two curved surfaces is obtained. And the computer calculates the three-dimensional coordinate data of the virtual ridgeline at the corner,
The measurement operation of one virtual ridgeline can be performed by a simple operation with a small number of steps of copying one measurement point indicating tool to the corner portion, and the workability can be greatly improved.

Also, three or more measuring elements are installed at the tip of the measuring point indicating tool so as to be separated from each other, and two measuring elements most suitable for the shape, size and direction of the corner of the measuring object are set. By selecting and using it, it is possible to operate the two tracing stylus manually on both curved surfaces sandwiching the corner of the measuring object so that it can be moved more easily. Workability is further improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an object to be measured and a measuring point indicator showing an embodiment of the method of the present invention.

FIG. 2 is a perspective view showing a relationship between two tracing styluses and a CAD data curved surface in FIG. 1;

FIG. 3 is a cross-sectional view showing a relationship between two tracing styluses, a CAD data curved surface, and a measurement object curved surface in FIG. 1;

FIG. 4 is a perspective view showing an example of a measurement point indicator used for virtual ridgeline measurement.

FIG. 5 is a perspective view of a corner portion of an object to be measured.

FIG. 6 is a perspective view for explaining a virtual ridgeline measuring method of the measuring object of FIG. 5 according to a conventional method.

FIG. 7 is a perspective view for explaining a virtual ridgeline measuring method according to another conventional method of the measuring object in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Measurement object 2 Corner part 3a 1st curved surface 3b 2nd curved surface 4 Virtual ridgeline 30 Measurement point indicator 33 Measuring element 33a, 33b (Measuring element used) 50 Computer

Continued on the front page F term (reference) 2F065 AA04 AA19 AA53 BB05 BB29 CC00 FF05 GG07 GG13 JJ03 JJ05 JJ26 QQ01 QQ23 QQ25 2F069 AA04 AA17 AA66 DD25 EE08 GG01 GG07 GG59 GG63 GG65 HH01H30

Claims (4)

[Claims] 1. A first and a second curved surface adjacent to each other across a corner portion of a measuring object are simultaneously contacted by two tracing styluses spaced apart from a tip of a measuring point indicator. The three-dimensional coordinate data of the tracing stylus is calculated and sampled by a computer, and based on the obtained three-dimensional coordinate data of the tracing stylus and the CAD data of the measuring object stored in advance in the computer, the first curved surface and the A three-dimensional measurement method of a virtual ridge line, wherein coordinate data of a point on a virtual ridge line, which is a virtual intersection line of an extension surface obtained by extending two curved surfaces to a corner portion side, is calculated. 2. The sampling measurement operation is performed at a plurality of sampling points by relatively moving a measuring point indicating tool in a direction of a corner, and the three-dimensional coordinate data of a tracing stylus obtained from the plurality of sampling points and the computer perform the sampling measurement operation. Calculating coordinate data of a virtual ridge line, which is a virtual intersection of an extension surface obtained by extending the first curved surface and the second curved surface to the corner portion side, based on CAD data of the measurement object stored in advance. The three-dimensional measurement method of a virtual ridgeline according to claim 1. 3. The displacement amount of the virtual ridge line from the CAD data is calculated by comparing and evaluating the three-dimensional coordinate data of the two tracing styluses with the CAD data of the object to be measured. 3. The three-dimensional measurement method of the virtual ridge line according to 2. 4. At least three measuring elements are installed at the tip of the measuring point indicating tool so as to be separated from each other, and two measuring elements suitable for the shape of the corner of the object to be measured are selected and used. The three-dimensional measuring method of a virtual ridgeline according to claim 1 or 2, wherein: