JPH07260452A - Three dimensional shape measuring method - Google Patents

Abstract

PURPOSE:To provide a method in which the three dimensional shape of an object to be measured can be measured precisely by a method wherein, when one object to be measured is measured by being divided into a plurality of times of measuring operations and pieces of measured data obtained by the respective measuring operations are composed, both pieces of measured data are composed precisely and simply. CONSTITUTION:Out of a plurality of regions which are set on the surface of an object 30 to be measured, a partially overlapped range D is formed in adjacent regions A, B, criterion spherical bodies 40 are arranged in at least three places in the overlapped range D, positions of at least three points on the surface of every criterion spherical body 40 are measured by a measuring means 22 in measurements in the individual regions A, B, the sphere center of every criterion spherical body 40 is found, and measured results of the object 30 to be measured in the individual regions A, B are composed by making use of the sphere center of every criterion spherical body 40 as a criterion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional shape measuring method, and more particularly to a method for measuring the three-dimensional shape of various objects, which is a non-contact type measuring means such as spot light. The present invention relates to a method of measuring the position of each point on the surface of the, and integrating the position information of these points to measure the three-dimensional shape of the measured object.

[0002]

2. Description of the Related Art A method of measuring a three-dimensional shape of an object to be measured by a non-contact type measuring means is used in various technical fields as a method of accurately and quickly measuring the three-dimensional shape of the object to be measured. In addition, various measuring devices to which such a three-dimensional shape measuring method can be applied have been proposed.

For example, there is a measuring device in which a measuring device of non-contact type measuring means is installed above a surface plate on which an object to be measured is placed so as to be movable along a plane parallel to the surface plate. While moving the measuring instrument forward, backward, leftward and rightward, at each position, the position of a point on the object to be measured which is located directly under the measuring instrument is measured. As a specific example of the non-contact type measuring means, for example, a spot light is emitted from the measuring device to a position directly below, and the reflected light reflected by the surface of the object to be measured is received again by the measuring device, and from the light receiving position. , There is one that measures the distance from the measuring device to the object to be measured based on the principle of triangulation. By subtracting the distance from the measuring device to the object to be measured from the distance from the measuring device to the surface of the surface plate, the height of the object to be measured at that point can be obtained. If the height of the object to be measured is obtained at many points on the object to be measured, the three-dimensional shape of the entire object to be measured can be measured.

[0004]

However, the above-described conventional three-dimensional shape measuring apparatus has a problem that when the size of the object to be measured becomes large, the measurement cannot be performed at all or the measurement result becomes inaccurate. .

First, the object to be measured must be large enough to be placed on a surface plate. Even if it is placed on the surface plate, it must be within the range that can be measured by the measuring instrument. The measuring instrument is attached so that it can be moved along the rails or beams, or is attached to the arm or support that can be expanded or contracted or rotated, so that it can be moved within a certain range. There is a limit to the range. Further, the wider the moving range of the measuring device, the more difficult it is to accurately control the movement, and the error in the position or the moving amount of the measuring device increases, so that the measurement accuracy deteriorates.

Therefore, a method of measuring one object to be measured in two times has been considered. First, half of the object to be measured is placed on the surface plate so that half of the object to be measured falls within the measuring range of the measuring instrument, and measurement is performed only within the range that can be measured by the measuring instrument. Next, so that the other half of the measured object is in the measurement range,
The object to be measured is moved and the other half is measured. This is a method in which the measurement data of each half of the object to be measured are connected at the boundary portions thereof so that the three-dimensional shape of the entire object to be measured can be measured.

However, this method has a problem that it is difficult to connect the measurement data for each half of the object to be measured, and the boundary between the two is not smoothly connected.
Improvement was requested.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, to measure one object by dividing it into a plurality of times, and combine the measurement data obtained in each measurement. Another object of the present invention is to provide a method capable of accurately and easily synthesizing both measurement data and accurately measuring the three-dimensional shape of an object to be measured.

[0009]

The three-dimensional shape measuring method according to the present invention, which solves the above-mentioned problems, is a movable non-contact measuring means for measuring the position of each point on an object to be measured, When measuring the three-dimensional shape of the DUT, divide the surface of the DUT into multiple areas, measure each area separately, and combine the measurement results to obtain the three-dimensional shape of the entire DUT. In the method for obtaining a shape, of a plurality of areas set on the surface of the object to be measured, a range is provided in which adjacent areas partially overlap each other, and reference spherical bodies are arranged at least at three positions in the overlapping range. When measuring in a region, the spherical center of each reference spherical body is obtained by measuring the position of at least three points on each surface of each reference spherical body by the measuring means, and the measurement result of the measured object in each region is obtained. , Based on the sphere center of each reference sphere Synthesized.

The object to be measured is usually measured in a state where it is placed on a stationary surface such as a surface plate whose surface is finished to be an accurate flat surface. However, even if it is not placed on the surface plate, it may be clamped or hung by some means and supported at a predetermined position. In this way, the surface serving as the reference in the state where the object to be measured is arranged at the fixed position is called the stationary surface.

As the non-contact type measuring means, various known measuring means such as a measuring device for measuring a distance by triangulation with a spot light such as a laser are used. The measurement principle and internal mechanism can be freely combined with known techniques. Instead of light, non-contact measurement means using various radiations, electromagnetic waves, magnetism, ultrasonic waves, etc. can also be adopted.

The moving mechanism of the non-contact type measuring means may have the same structure as the moving mechanism in the known three-dimensional shape measuring apparatus. The movement of the measuring means may be performed by freely combining linear movement in the front-rear, left-right, or vertical directions, and a turning movement in a horizontal plane or a vertical plane, as required. As the moving mechanism, it is preferable that the moving mechanism is capable of tilting the measuring direction of the measuring means. The measuring direction of the measuring means is the irradiation direction of the spot light, and is the direction in which the measuring point to be measured should be arranged.

The reference spherical body may be a complete spherical body, or a partial spherical body such as one in which a support pillar projects from a part of the spherical body, a hemisphere, or a combination of a solid body and a spherical body such as a rectangular parallelepiped. . It suffices that the measuring points at which the position can be measured by the measuring means have spherical surfaces capable of taking at least three points. The diameter of the reference spherical body and the area of the spherical surface may be set in consideration of the measuring principle and accuracy of the measuring means, the processing accuracy of the spherical surface, and the like. For example, in the case of a measuring device that performs triangulation using spot light, the spot light diameter is 1
Those having a spherical diameter of about 0 to 100 times are preferable. The reference spherical body is preferably made of a material that can be formed into an accurate and smooth spherical surface having no unevenness or distortion that may affect the measurement, and specifically, ceramic is a preferable material. Hard metals, synthetic resins, and glassy materials can also be used.

The reference spherical body can be temporarily fixed to the object to be measured. Specifically, various fastening means such as an adhesive, an adhesive tape, an adhesive tape, a pin, and a screw fitting may be adopted. A pin or a metal fitting may be integrally formed on the reference spherical body. The reference spherical body may be attached in close contact with the surface of the object to be measured, or may be attached to a position protruding from the surface of the object to be measured. When the reference spherical body is attached to the object to be measured, it is necessary to attach the spherical portion at a position where measurement can be performed by a measuring means so that measurement can be performed at three or more points. If the reference spherical body is a perfect spherical body, it is convenient because the measurement can be surely performed regardless of the posture in which the spherical body is mounted.

To measure a three-dimensional shape of an object to be measured, the surface of the object to be measured is divided into a plurality of areas, the measurement is performed separately for each area, and the respective measurement results are combined to form a three-dimensional shape of the entire object to be measured. Get the original shape. The setting method of each area and the number of divided areas can be freely set in consideration of conditions such as the shape and size of the object to be measured and the structure of the measuring device. Under normal conditions, the number of regions is sufficient to be two, but it is also possible to divide into three or more regions.

Among a plurality of divided areas, adjacent areas are provided with a partial overlapping area, and the reference spherical body is arranged at least at three positions in the overlapping area. The width and size of this overlapping range are set to such an extent that the three reference spherical bodies can be arranged with a certain distance therebetween. Three
The wider the range having the reference spherical bodies as vertices becomes, the higher the measurement accuracy becomes. Therefore, if the size of the overlapping range and the positions of the three reference spherical bodies are determined according to the required measurement accuracy. Good.

In such a state, the three-dimensional shape of each region is measured by a usual method. When measuring each area, the object to be measured may be moved or the posture thereof may be changed so that the measurement in each area can be performed as well as possible. At the time of measurement in each of these regions, the position of at least three points on each surface of each reference spherical body is measured by the measuring means separately from the measurement of the measured object itself.

When the positions of at least three points on the surface of one reference spherical body are known, the position of the sphere center of the reference spherical body can be obtained by geometrical arithmetic processing. For example, if the positions of three points on the spherical surface and the radius of the sphere are known, the center of the sphere can be determined, and if the positions of four points that are not on the same circle are known, the center of the sphere can be determined without knowing the radius. Such arithmetic processing may be performed using an arithmetic processing device such as a microcomputer and an arithmetic processing program incorporated in the control device of the measuring means. It should be noted that in order to obtain the spherical center of the reference spherical body, it is theoretically necessary to know the positions of at least three points, but the number of positions exceeding the theoretically necessary number is measured to reduce the influence of the measurement error. You can also

The measurement data relating to the three-dimensional shape of the measured object measured in each region is combined to obtain the three-dimensional shape of the entire measured object. Since the sphere center positions of the three reference spherical bodies are obtained for each region, the measurement data of each region may be synthesized by superimposing the sphere center positions on each other. Note that the overlapping range is the same regardless of which measurement data is used, and thus only one measurement data may be used or an average value of both measurement data may be taken. Such combination of measurement data can be performed quickly and accurately by using an arithmetic processing device such as a computer.

[0020]

If the surface of the object to be measured is divided into a plurality of areas and the overlapping areas are provided in the adjacent areas, the measurement data in this overlapping area will represent the same object in both areas.

Therefore, if a reference point is provided in the overlapping range and the positions of the reference points in the measurement data in both areas are made to coincide with each other and both measurement data are combined, accurate combination is achieved. You can do it. In the case of a three-dimensional shape, normally, when the positions of three points are determined, the posture thereof is determined, so that at least three reference points should be provided in the overlapping range.

However, even if the display of the reference point is drawn on the surface of the object to be measured, it is difficult to perform the measurement accurately by aligning the measuring means with the reference point display position, and in addition, the drawing line, the groove, On the display of the reference point physically formed by the protrusion,
Due to the constant spread, it is not possible to measure the reference point in the strict sense. If the measurement position of the reference point has an error or variation, even if the measurement data is combined based on such a reference point, accurate combination cannot be achieved.

Therefore, if a reference spherical body having a certain size is arranged in the overlapping range, it is easy to measure the position of an arbitrary measurement point on the reference spherical body, and the position of the measurement point is predetermined. No matter where the positions of the several measuring points are chosen, the position of the sphere center calculated from the positions of these measuring points is mathematically determined exactly. If the position of the sphere center obtained in this way is used as a reference point when synthesizing the above-mentioned measurement data, the position of the reference point measured in any region,
An accurate position is always shown, and if the measurement data is synthesized based on the position of such an accurate reference point, an accurate three-dimensional shape of the entire measured object can be obtained.

[0024]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of the three-dimensional shape measuring apparatus. A gate-shaped support structure 20 and a measuring device 2 supported by the support structure 20 on a surface plate 10 made of a hard metal, ceramics, or other material having high rigidity
2 is attached. The measuring instrument 20 irradiates the spot light R from its lower surface, captures the reflected light reflected at the measuring point again by the measuring instrument 20, and measures the position of the measuring point by the principle of triangulation. The measuring instrument 22 is mounted on the support structure 20 so as to be able to horizontally move or turn to move.

An object to be measured 30 for measuring a three-dimensional shape is placed on the surface plate 10. The device under test 30 has an arrow A
Area A on the side indicated by −A and area B on the side indicated by arrow BB
And, the three-dimensional shape is measured in two areas.
Regions A and B are adjacent to each other and overlap each other to form an overlapping range D. In the overlapping range D, small balls 40 serving as reference spherical bodies are attached to three positions on the surface of the DUT 30.

A procedure for measuring the three-dimensional shape of the object 30 to be measured using the above measuring device will be described.

For each of the areas A and B, the three-dimensional shape is measured by the usual procedure. For each of the areas A and B, the measurement may be performed by moving the position of the object to be measured 30 or changing the posture thereof so that the measurement device 20 can easily perform the measurement.

At the time of measurement in each of the areas A and B, with respect to the three small spheres 40 arranged in the overlapping range D, the position of the measuring device 20 is also set at three points on the surface of each small sphere 40. Take a measurement. The measurement point of each small ball 40 may be set arbitrarily. In the areas A and B, it is not necessary to make the measurement points of the small balls 40 the same.

From the measurement position data of three points of each small ball 40,
The ball center C of each small ball 40 is obtained. For example, as shown in FIG. 2, if the spot light R is applied and the positions of the three points P _{1 to} P ₃ are measured, the sphere center C is calculated from the positions of the points P _{1 to} P ₃ and the value of the radius of the sphere. The position of is required.

In this way, after the measurement data is obtained for each of the area A and the area B, both measurement data are combined. At this time, since the sphere center C of the small sphere 40 exists in all the measurement data, the positions of the three sphere centers C are represented by the respective measurement data so that both the measurement data match. By moving the three-dimensional shape described above, it is possible to accurately combine both measurement data and obtain an accurate three-dimensional shape of the entire measured object 30.

[0032]

As described above, according to the three-dimensional shape measuring method of the present invention, by using the above-mentioned reference spherical body, the measurement data of a plurality of separately measured regions can be obtained.
It is possible to accurately match and synthesize.

As a result, by dividing an object to be measured into a plurality of regions for measurement, even if the object to be measured has a size or a shape that is difficult to measure at once, there is no problem in accurate three-dimensional measurement. The shape can be measured, which can greatly contribute to the efficiency of the three-dimensional shape measurement of various articles and the improvement of workability.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a measurement state of a reference spherical body.

[Explanation of symbols]

10 surface plate 20 support structure 22 measuring device 30 object to be measured 40 small sphere (reference spherical body) A, B measurement area C sphere center D overlapping range P _{1 to} P ₃ measurement point on reference sphere R spot light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahata Ichiyanagi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. When measuring the three-dimensional shape of an object to be measured by measuring the position of each point on the object to be measured by a movable non-contact type measuring means, a plurality of areas are formed on the surface of the object to be measured. In the method of obtaining the three-dimensional shape of the entire DUT by combining the respective measurement results, the measurement is performed separately for each region, and among the plurality of regions set on the surface of the DUT, The regions to be partially overlapped with each other are provided, and the reference spherical bodies are arranged in at least three places of the overlapping regions, and at the time of measurement in each region, at least three points on each surface of each reference spherical body are described above. Three-dimensional, characterized in that the sphere center of each reference spherical body is obtained by measuring the position with a measuring means, and the measurement result of the object to be measured in each region is synthesized with reference to the sphere center of each reference spherical body. Shape measurement method.