JPH09257427A - Method and apparatus for measurement of size and shape of object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus, for the precise measurement of the size and the shape of an object, in which, when the size and the shape of the object to be measured are measured by using a plurality of sensors, their measurement is not affected even when the positional relationship between the sensors is changed and in which their measurement is not affected even when the position and the posture of the object to be measured are changed. SOLUTION: A reference object 5 which has at least two sets of mutually corresponding cross planes whose mutual positional relationship is known in such a way that the direction of an intersection line is different and whose size is known is arranged so as to be close to an object 4 to be measured. Then, the reference object 5 and the object 4 to be measured are measured simultaneously. On the basis of information on the reference object 5, measured results by a plurality of sensors are integrated so as to align their positions and directions precisely. On the basis of the positional relationship between respective faces of the object 4, to be measured, after their integration, its size is computed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the size and shape of an object such as an industrial product with high accuracy for measuring the size and shape of the object such as thickness and width.

[0002]

2. Description of the Related Art In order to measure the dimensions such as thickness and width of an object, or the shapes such as irregularities and bends, a plurality of distance measuring sensors such as a laser range finder are used to measure a plurality of distances from a predetermined position. Conventionally, a method for obtaining a location and calculating a desired dimension by combining these has been conventionally performed, but this method has a difficulty in that a positional relationship between sensors must be strictly maintained. In order to solve this problem, the present applicant has previously proposed a method using an area three-dimensional sensor (Japanese Patent Application No. 06-072723). According to the method of this application, even when a plurality of sensors are used to determine the size of an object, even if the positional relationship between the sensors is changed, it is possible to perform measurement without being affected by the change.

The above invention will be described below with reference to FIGS. Fig. 3 shows 1 of the device arrangement for measuring the thickness of an object.
It is an example. In FIG. 3, reference numerals 1a and 1b are area three-dimensional sensors, which are projection devices 2 for projecting a pattern on the surface of an object.
a, 2b and image pickup devices 3a, 3b for picking up an image of a pattern projected on the object surface from a direction different from the projection, and processing distortion of the picked-up pattern image to obtain a large number of object surfaces in the measurement area. Measure the three-dimensional coordinates of the point. The area three-dimensional sensors 1a, 1b are arranged so as to measure from both sides of the object to be measured 4 and a reference object 5 whose dimensions are known (in this case, the thickness d is known) so as to sandwich it in the thickness direction. The spatial coordinates of a large number of points measured by the area three-dimensional sensor are respectively identified to which surface of which object, and the surface expression is determined so that each surface is statistically best fitted. .

FIG. 4A shows the result of measurement by the area three-dimensional sensor 1a, which shows the area 3 of the object 4 to be measured.
The measurement fitting result 4-1 of the surface on the side of the dimension sensor 1a and the measurement fitting result 5-1 of the surface of the area 3D sensor 1a on the side of the area 3D sensor 1a among the reference objects 5 of known dimensions are X ₁ Y ₁ peculiar to the area 3D sensor 1a. Z ₁ - is represented in the coordinate system. Similarly, FIG. 4B shows the result measured by the area three-dimensional sensor 1b, which is the result of measurement fitting 4-2 of the surface of the measured object 4 on the side of the area three-dimensional sensor 1b and the reference object 5 whose dimensions are known. The measurement fitting result 5-2 of the surface on the area three-dimensional sensor 1b side is represented by the X ₂ Y ₂ Z ₂ -coordinate system unique to the area three-dimensional sensor 1b. Here, the measurement fitting results 5-1 and 5-2 of the surface of the reference object 5 are the thickness d.
By using the condition that the distances are parallel to each other, the respective measurement fitting results can be integrated as shown in FIG. 4C, and the measurement fitting results 4-1 and 4-of the surface of the measured object 4 can be integrated.
The thickness T of the measured object 4 can be obtained from the relationship of 2.

As described above, in the above invention, the X ₃ Y ₁ Z ₁ specific to the area three-dimensional sensor 1a and the measurement result measured by the coordinate system and the X ₂ Y ₂ specific to the area three dimensional sensor 1b.
In order to integrate the measurement results measured in the Z ₂ -coordinate system, the thickness information of the reference object 5 whose dimensions are known, more accurately, the information regarding the direction in which the two surfaces of the reference object 5 whose dimensions are known are parallel, and its 2 The positional information that the distance between the surfaces is d is used, and the positional relationship between both coordinate systems as used in the past, in other words, the positional relationship between both sensors is not used at all, so the positional relationship between both sensors is not used. Even if fluctuates, it is possible to perform accurate thickness measurement without being affected by it.

[0006]

However, in the case of the thickness measuring method shown in FIG. 3, in order to integrate the measurement result of the area three-dimensional sensor 1a and the measurement result of the area three-dimensional sensor 1b, a reference object of known size is used. Since the thickness information of No. 4 is used, accurate alignment can be performed in the thickness direction, but accurate alignment cannot be performed in the height direction and the length direction of the object. Therefore, a measurement error occurs depending on the posture of the measured object 4. There was a problem of doing. This will be described in detail with reference to FIG.

FIG. 5 shows a state after integration when viewed from the length direction of the object. 5A and 5B show the case where the object to be measured and the reference object whose dimensions are known are parallel to each other. In either case, the positions are accurately aligned in the thickness direction. FIG.
Fig. 5 (a) shows the case in which the alignment in the height direction is accurate.
(B) is a case where the height direction alignment is incorrect. In this case, the height direction alignment error does not affect the thickness measurement result of the measured object, and both are accurate. The thickness T can be measured.

Next, FIGS. 5 (c) and 5 (d) show the case where the measured object is not parallel to the reference object whose dimensions are known, that is, when the measured object is tilted with respect to the reference object whose dimensions are known. 5
In (c), if the alignment in the height direction is accurate,
(D) is a case where the alignment in the height direction is incorrect. As can be seen from the figure, in FIG.
However, in FIG. 5D, the accurate thickness T cannot be measured due to the vertical shift, and a measurement error of ΔT occurs. Where ΔT = ΔY · sin θ (ΔY
Is a position displacement amount in the height direction, and θ is a displacement angle from parallel), and the greater the displacement in alignment and the greater the inclination from parallel, the greater the thickness measurement error. Similarly, if the alignment in the length direction is not accurate, the measurement of the thickness becomes inaccurate when the parallelism in the length direction between the measured object and the reference object whose dimensions are known is wrong. . In the above invention, since the reference object whose dimensions are known has only the information in the thickness direction, it is not possible to accurately align the positions in the height direction and the length direction, and as described above, the posture of the measured object is changed. There was a problem that the measurement became inaccurate when there was a change.

The position in the height direction and the position in the length direction of the common object 5 whose dimensions are known are shown in the image pickup devices 3a and 3 shown in FIG.
If it is possible to accurately determine the edge position of the common object from the image captured in b, for example, the position can be accurately aligned in the height direction and the length direction, and the projection device 2a, Since the light projected from 2b is not light having a uniform brightness distribution but light patterned for measuring spatial coordinates, the edge of the reference object 5 having a plate-like dimension as shown in FIG. 3 is known. Not suitable for measuring position. Therefore, the edge position cannot be accurately measured, and the alignment is inaccurate in the height direction and the length direction.

The present invention has been made in order to solve such a problem, and not only is it possible to perform accurate dimension measurement which is not affected even if the positional relationship between the two sensors fluctuates, but also to measure the object to be measured. An object of the present invention is to provide a method and apparatus for measuring the size of an object, which enables accurate size measurement even when the posture changes.

[0011]

As described above, in order to perform accurate dimension measurement even when the posture of the object to be measured changes, it is necessary to accurately measure when combining the measurement results of the three-dimensional area sensors. The position and direction must be adjusted. In order to realize this, in the dimension measuring method and apparatus of the present invention, when combining based on the known dimension information of the reference object, the shape of the reference object is changed so that the position and the direction can be accurately combined in all directions. It has all the information about the position and orientation. Specifically, the reference object should have at least two sets of corresponding intersecting planes whose mutual positional relations are known so that the directions of the intersecting lines are different, in the measurement area of each area three-dimensional sensor. I have to. This will be described in detail with reference to the drawings.

In FIG. 6 (a), a reference object 5 of known dimensions is composed of intersecting planes 6 and 8. The intersecting plane 6 is composed of two planes intersecting at the intersecting line 7, and the intersecting plane 8 is composed of two planes intersecting at the intersecting line 9. Also, intersections 6 and 8
Have a known mutual positional relationship and form a corresponding set. The first area three-dimensional sensor (not shown) measures the side of the intersecting surface 6, and the measurement result is the measurement fitting results 5-1a and 5-1b for the intersecting surface 6 as shown in FIG. 6B. The intersection line 5-1c is represented by the X ₁ Y ₁ Z ₁ -coordinate system unique to the first area three-dimensional sensor.

A second area three-dimensional sensor (not shown) measures the side of the intersection 8 and the measurement result is shown in FIG.
As shown in (c), the measurement fitting results 5-2a and 5-2b and the intersection line 5-2c with respect to the intersecting surface 8 are expressed in the X ₂ Y ₂ Z ₂ -coordinate system unique to the second area three-dimensional sensor. ing. Since the positional relationship between the intersecting surfaces 6 and 8 is known, the measurement fitting results 5-1a, 5-1b, 5-2a, 5-2b
As shown in FIG. 6D so that the intersection lines 5-1c and 5-2c satisfy the known positional relationship, the measurement results of both area three-dimensional sensors can be integrated. However,
Since there is no position information in the direction of the line of intersection, that is, the direction of the arrow in FIG. 6D, the position cannot be accurately aligned.

FIG. 7 (a) is another reference object of known dimensions, which is composed of intersecting planes 10 and 12, and the intersecting planes 10 and 12 also correspond to each other because their mutual positional relationship is already known. It forms one group. 11 is an intersection plane 10
Is a line of intersection, and 13 is a line of intersection of the intersecting planes 12. Intersection 10
Side is measured by the first area three-dimensional sensor, and the intersection 1
When the side 2 is measured by the second area three-dimensional sensor,
The measurement results can be integrated as shown in FIG. 7B, but similarly, the positions cannot be accurately aligned in the direction of the intersecting line (the direction of the arrow in FIG. 7B). That is, when either the reference object shown in FIG. 6 (a) or the reference object shown in FIG. 7 (a) is used alone, the measurement results of the area three-dimensional sensors are accurately aligned in position and direction. Cannot be integrated.

FIG. 8 shows a case in which both the reference object shown in FIG. 6A and the reference object shown in FIG. 7A are used. In the example of this figure, the measured object 4 is sandwiched. The reference objects 5 are arranged above and below. In this case, since the intersecting directions of the two sets of intersecting directions are different from each other, all the information necessary to integrate the measurement results of both area three-dimensional sensors is available, and the results are obtained by accurately aligning all the positions and directions. Can be integrated.

As described above, at least two sets of corresponding intersecting planes whose positional relationships are known are provided in the measurement areas of the area three-dimensional sensors of the reference object so that the directions of the intersecting lines are different from each other. If it has, since it has all the information about the position and direction required when combining the measurement results of each area three-dimensional sensor, it becomes possible to accurately match the position and direction and combine the measurement results. Therefore, even if the posture of the object to be measured changes, the dimension can be measured accurately without being affected by the change. The directions of the lines of intersection of the two sets of intersecting planes need not be the same, but as can be easily understood, the closer they are to the right angles, the more accurately the positions can be aligned.

Note that FIG. 8 is an example, and the reference object does not have to be divided into two parts above and below the object to be measured 4, and may be integrated as shown in FIG. 9 (a). good. Further, various shapes are possible, for example, as shown in FIG.
The shape shown in FIG. The two lines of intersection of the pair of intersecting surfaces do not have to be parallel, but it is easier to manufacture them if they are parallel, and it is easier to calculate when they are integrated.

[0018]

1 is one embodiment of the method or apparatus of the present invention. A reference object 5 having a known size is arranged below the measured object 4 and two area three-dimensional sensors 1a and 1b measure the measured object 4 and the reference object 5 having a known size from both sides. FIG. 2A shows the result measured by the area three-dimensional sensor 1a, and the result of measurement fitting of the surface of the measured object 4 on the side of the area three-dimensional sensor 1a 4-
1 and the measurement fitting result 5-1 of the surface of the reference object 5 of known dimensions on the side of the area three-dimensional sensor 1a is represented by the X ₁ Y ₁ Z ₁ -coordinate system unique to the area three-dimensional sensor 1a. Similarly, FIG. 2B shows the result measured by the area three-dimensional sensor 1b, and the result of measurement fitting 4-2 of the surface of the measured object 4 on the side of the area three-dimensional sensor 1b and the reference object 5 whose dimensions are known. The measurement fitting result 5-2 of the surface on the area three-dimensional sensor 1b side is represented by the X ₂ Y ₂ Z ₂ -coordinate system unique to the area three-dimensional sensor 1b.

As described above, the measurement results of both area three-dimensional sensors are accurately integrated so that the relationship between the measurement fitting results 5-1 and 5-2 of the reference object 5 whose dimensions are known has a known positional relationship. As a result, the relationship between the measurement fitting results 4-1 and 4-2 of the surface of the measured object 4 is related as shown in FIG. 2C, and the thickness T of the measured object 4 is calculated. This value is not affected by the position variation of the area three-dimensional sensor for the reason already explained, and the measured object 4
It is an accurate value that will not be affected by changes in the position or posture of.

Although FIG. 1 shows an example of thickness measurement, the present invention is not necessarily limited to such dimension measurement applications, and can be applied to a wide range of dimension and shape measurement applications such as bending measurement and angle measurement. is there. Also, the area three-dimensional sensor is not limited to two, and can be applied when a larger number is used.

[0021]

As described above, according to the measuring method and apparatus of the present invention, not only the measured value of the dimension is not affected by the positional variation between the sensors, but also the variation of the position and the posture of the target object. Since it is not affected by, it is possible to measure extremely accurate dimensions, and its application range is extremely wide.
The effect is enormous.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a result measured by FIG.

FIG. 3 is a schematic view of an apparatus of a conventional dimension measuring method.

FIG. 4 is an explanatory diagram showing a result measured by FIG.

FIG. 5 is an explanatory diagram for explaining problems of the conventional method.

FIG. 6 is a view for explaining the action of the first set of intersecting surfaces.

FIG. 7 is a view for explaining the action of the second set of intersecting surfaces.

FIG. 8 is a diagram showing a combination of first and second intersecting surfaces.

FIG. 9 is a diagram showing another example of a combination of first and second intersecting surfaces.

[Explanation of symbols]

1a, 1b Area 3D sensor 2a, 2b Projection device 3a, 3b Imaging device 4 Object to be measured 4-1 and 4-2 Measurement result of surface of object 4 to be measured 5 Reference object with known dimensions 5-1 and 5- 1a, 5-1b, 5-1d, 5-1e, 5-2, 5-2a, 5-2b, 5-2d, 5-2e Measurement fitting result of the surface of the reference object 5 whose dimensions are known 5-1c, 5 -1f, 5-2c, 5-2f Intersection line 6,8,10,12 Intersection plane 7,9,11,13 Intersection line

Claims (2)

[Claims] 1. A plurality of area three-dimensional sensors measure the spatial position of each part of an object to be measured and a reference object whose dimensions are known, and the space of the object to be measured is measured by each area three-dimensional sensor. A method for measuring a dimension of an object by combining a position on the basis of a known dimension of the reference object, wherein a pair of corresponding intersecting planes whose mutual positional relations are known intersect each other. A method for measuring the size and shape of an object, characterized in that at least two sets of reference objects having different directions are arranged in the measurement area of each area three-dimensional sensor. 2. An object to be measured and a reference object whose dimensions are known are arranged close to each other, and a plurality of area three-dimensional sensors for measuring the spatial position of each part of these objects are provided, and the object measured by each area three-dimensional sensor is provided. An object size measuring apparatus for measuring the size of an object to be measured by combining the spatial position of a measurement object based on the known size of the reference object, wherein the reference object is within the measurement area of each area three-dimensional sensor. An apparatus for measuring the size and shape of an object, characterized in that at least two sets of corresponding intersecting planes whose positional relationships are known are provided so that the directions of the intersecting lines are different.