JPH07243822A - Method and device for measuring three-dimensional shape - Google Patents

Abstract

PURPOSE:To provide a method and device for measuring three-dimensional shapes by which the position and attitude of a measuring means are found so accurately that the measuring accuracy can be improved and the measuring work efficiency be also enhanced. CONSTITUTION:At least three points P1-P3 and S1-S3 on respective surfaces of reference spherical body 40 and reference plane body 30 which are placed in position beforehand are selected and their relative positions against a measuring means 20 are subject to measurement by the movable and non-contact type means 20. Based on the obtained relative positions of the respective points P1P3 on the body 40, the relative position of the center C of the body 40 against the means 20 is calculated, while the relative attitude of the body 30 against the means 20 is calculated based on the obtained relative positions of the respective points S1-S3 on the body 30. Thus, information concerning the position and attitude of the means 20 are obtained on the basis of the obtained results.

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, in the conventional three-dimensional shape measuring method and apparatus as described above,
There is a problem in that it takes time to prepare before starting the measurement, and the measurement accuracy of the three-dimensional shape is not sufficient.

That is, in the conventional measuring apparatus as described above, if the surface of the surface plate on which the object to be measured is placed and the moving surface on which the measuring device moves are not exactly parallel, the object to be measured is The height measurements at each point in will be inaccurate, resulting in
The measurement accuracy of the three-dimensional shape deteriorates. In addition, if the direction of the spot light emitted from the measuring device is not exactly right below, an error occurs in the distance from the measuring device to the object to be measured.

Therefore, in the conventional measuring apparatus, when the measuring instrument and its moving mechanism are installed on the surface plate, a level or the like is used so that the moving surfaces of the surface plate and the measuring equipment are parallel to each other. In addition, it was necessary to perform careful work, which was a very troublesome work. Also, while using the measuring device, due to external force such as vibration or shock, or environmental change,
The measurement result may be inaccurate due to the displacement of the position and orientation of the measuring instrument and the moving mechanism. Therefore, on a regular basis,
In some cases, it was necessary to inspect and correct the mounting position and posture of the measuring instrument and the moving mechanism.

Further, there is no problem when the measurement surface of the object to be measured faces the irradiation light from the measuring device, but the measurement surface of the object to be measured is inclined with respect to the irradiation light from the measurement. If so, the reflected light from the measurement surface cannot be captured by the measuring instrument, and measurement cannot be performed. Therefore, the posture of the measuring instrument can be changed so that the irradiation light from the measuring instrument is directly opposed to the measuring surface of the measuring object, and the measuring instrument can be swung freely to measure the measuring surface of the measuring object. It was considered that the irradiation direction of light was changed according to the shape of.

However, if the measuring instrument is tilted in order to change the light irradiation direction, the inclination of the measuring instrument with respect to the surface plate is naturally changed, so that the measuring instrument is in the original state in which it is directly facing the surface plate surface. There is no continuity with the measurement results. Even if the distance from the measuring instrument to the measuring point is the same, the height of the measuring point varies depending on the inclination of the measuring instrument. Therefore, it was not possible to measure one object to be measured by changing the inclination of the measuring device depending on the place.

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art and to improve the measurement accuracy of a three-dimensional shape by accurately knowing the position and orientation of the measuring device, that is, the measuring means. A three-dimensional measuring method that can perform measurement without problems even if the measuring means is tilted or the posture is changed according to the shape of the object to be measured, and that the measuring means is easy to install and adjust without difficulty. And to provide a device.

[0010]

A three-dimensional measuring device according to the present invention, which solves the above-mentioned problems, is a non-contact type measuring means which is movable with respect to a stationary object to be measured. In the method of measuring the position of each point, to measure the three-dimensional shape of the object to be measured, the stationary surface of the object to be measured, a reference spherical body and a reference plane body are arranged, the reference spherical body and With respect to at least three points on each surface of the reference flat body, the relative position with respect to the measuring means is measured by the measuring means, and the center of the reference spherical body with respect to the measuring means is measured from the position of each point on the reference spherical body measured here. Of the relative position of the reference flat body relative to the measuring means from the position of each point on the reference flat body, based on these results, of the measuring means for the stationary surface of the measured object. Know position and attitude.

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 performing distance measurement 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 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 is set in advance separately from the measuring means. Specifically, for a stationary surface such as a surface plate,
It may be attached at an appropriate position, may be integrally formed on the surface plate, or may be fixed with screws or metal fittings. The reference spherical body may be provided at a position distant from the stationary surface, for example, by providing the reference spherical body at the tip of a column standing on the surface plate. Further, the reference spherical body may be detachably attached at a plurality of positions on a stationary surface such as a surface plate. If the mounting position of the reference spherical body can be changed, the reference spherical body can be mounted in a place that does not interfere with the measurement according to the shape of the object to be measured. In the present invention, it suffices that the reference spherical body serving as the reference of the position of the measuring means is fixed so as not to move during a continuous series of measuring operations.

Similar to the reference spherical body, the reference plane body can be freely set in its plane shape and area as long as it has a plane capable of obtaining at least three or more measurement points at which the position can be measured by the measuring means. it can. The reference plane body is formed of the same material as the reference spherical body. The reference plane body may be on the same surface as the stationary surface or at a position away from the stationary surface as long as it is arranged at a fixed position and posture with respect to the stationary surface of the object to be measured. The reference plane body may be arranged in parallel to the stationary surface or may be inclined, and its inclination angle can be set arbitrarily.
Similarly to the reference spherical body, the reference plane body may be detachably attached to a plurality of positions on a stationary surface such as a surface plate. The reference plane body and the reference spherical body may be integrally formed so that both can be handled together.

A reference plane represented by the surface of the reference plane body,
One coordinate system is determined based on the origin represented by the spherical center of the reference spherical body. This coordinate system is an absolute coordinate system that does not change due to changes in the moving position and orientation of the measuring means.

In the present invention, the position and orientation of the measuring means itself is known by performing the measurement on the reference spherical body and the reference plane body by the measuring means.

That is, the measuring means measures the positions of at least three measuring points on the respective surfaces of the reference spherical body and the reference plane body. Here, what is measured is a relative position based on the position and orientation of the measuring means.

The relative position of the sphere center of the reference spherical body with respect to the measuring means is obtained by performing appropriate arithmetic processing from the positions of at least three points on the reference spherical body measured here in accordance with the law of geometry. To be 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. 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 and the radius of the reference spherical body, but if the position data of four points is available, the radius may not be known. The center of the sphere can be found. Further, by measuring the number of positions that exceeds the theoretically required number, the error in the measurement position can be reduced. The relative attitude of the reference plane body with respect to the measuring means is obtained from the positions of the three points on the reference plane body. The calculation processing at this time is performed in the same manner as in the case of the reference spherical body.

Based on the relative position of the spherical center of the reference spherical body with respect to the measuring means and the relative attitude of the reference plane body with respect to the measuring means, in the absolute coordinate system determined by the reference spherical body and the reference plane body, The position and orientation of the measuring means are required.

Based on the obtained information on the position and orientation of the measuring means, the information on the position and orientation of the measuring means in the movement control system of the measuring means is corrected and the measurement data is corrected.

[0023]

If the origin position of the coordinate and the plane showing the direction of the coordinate axis are determined, one coordinate system can be determined. Therefore,
It is possible to determine a coordinate system in which the sphere center of the fixed reference spherical body is the origin and the surface of the reference plane is the reference plane.

Next, if the positions of at least three points on the spherical surface are known, the position of the center of the sphere can be obtained. That is, if the positions of three points on the spherical surface and the radius of the sphere, or the positions of four points on the spherical surface are determined, the center of the sphere is determined. Further, if the positions of three points on the plane are known, the inclination of the plane, that is, the posture can be obtained.

Therefore, if the measuring means measures the positions of at least three points on the respective surfaces of the reference spherical body and the reference plane body, which are separately arranged from the measuring means, the reference spherical body of the measuring means is measured. The relative position of the center of the sphere and the relative attitude of the plane of the reference plane body are obtained. Here, if the absolute coordinate system determined by the sphere center of the reference spherical body and the plane of the reference plane body is used as a reference, the position and orientation of the measuring means in this coordinate system can be obtained.

If the method of measuring the position of a point on the reference spherical body is adopted when obtaining the origin of the absolute coordinate system, the origin itself is provided and the position can be measured by the measuring means. In comparison, it is much easier to operate and more accurate. This is because, for example, even if an origin display is provided on the surface of a surface plate or the like, it is difficult to perform measurement by accurately aligning the measuring means with the origin display position, and moreover, in the physically formed origin display, Since there is a certain spread, it is difficult to measure the origin in a strict sense. However, it is easy to measure the position of any point on the reference spherical body having a certain size. Further, no matter where the positions of the plurality of measurement points are selected, the position of the center of the sphere calculated from the positions of those measurement points can be mathematically determined strictly.

In this way, if the accurate position and orientation of the measuring means are obtained, there will be an installation error when the measuring means is installed, or a manufacturing error or a mounting error in the member forming the measuring means and its moving mechanism. Even if there is an error or variation in the position determination or control of the measuring means inside the moving mechanism, it is possible to easily correct the influence of the error or variation on the measurement result.

That is, information about the position and orientation of the measuring means can be added to the calculation elements at the time of measurement without physically adjusting or correcting the installation of the measuring means physically. Just process the information,
The deviation of the position and orientation of the measuring means is corrected, and the measurement accuracy can be improved.

Further, even if the position error due to the movement of the measuring means is accumulated by performing continuous measurement, the position of the measuring means using the above-mentioned reference spherical body and reference plane body at an appropriate stage. If the position and posture information of the measuring means is corrected by measuring the position and the posture, the error will not be accumulated and the measurement accuracy will not be significantly affected.

Measurement of the position and orientation of the measuring means using the above-mentioned reference spherical body and reference plane body even when an operation for tilting the measuring direction of the measuring means is performed according to the shape of the object to be measured. If the position and orientation information associated with the inclination of the measurement direction is corrected by performing the above, accurate measurement can be performed even when the measurement direction is inclined. In addition, even if the measurement direction is not tilted and tilted or the tilt angle is different for one measurement object, the measurement results in those different states are shown in each state. It is possible to process all the measurement results in the same way by adding the correction according to the position and the posture of the measuring means in.

[0031]

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 22, a traveling support column 24, a swivel unit 25, and a rotary arm 2 are mounted on a thick plate-shaped surface plate 10 made of a hard metal, ceramics, or other material having high rigidity.
A measuring device 20, which is a non-contact type measuring means, is attached via 6 or the like. The support structure 22 is provided in a beam shape in the horizontal direction across the center of the surface plate 10 to both ends.
The traveling column 24 is freely movable horizontally along the support structure 22. At the lower part of the traveling column 24,
5 turns horizontally. The rotating arm 26 extending in the horizontal direction with respect to the revolving unit 25 rotates in the vertical direction together with the measuring device 20 at the tip. By combining the movements of the traveling column 24, the revolving unit 25, and the rotary arm 26, the measuring instrument 20 can be moved to any place on the surface plate 10, and the inclination of the measuring instrument 20 can be freely changed. It has become.

An object to be measured X for measuring a three-dimensional shape is placed on the surface plate 10. A reference spherical body 40 and a reference plane body 30 are mounted on the surface plate 10 on the side of the object to be measured X. The reference plane body 30 is made of a thin rectangular ceramic plate, and its surface is finished in an accurate plane. If one example of the dimensions of the reference plane body 30 is described, 5 × 1
It is about 0 cm, and its flatness is finished to about 2 μm. The surface of the reference plane body 30 is attached in parallel with the surface of the surface plate 10.

The reference spherical body 40 is a spherical body made of ceramics, and is attached to a position slightly higher than the surface of the surface plate 10 by a vertical support shaft 42 joined to the bottom.

A method of measuring the three-dimensional shape of the object X to be measured using the measuring device having the above structure will be described.

First, the measuring device 20 measures the positions of the three points S _{1 to} S ₃ on the surface of the reference flat body 30. When the positions of the three points on the plane are determined, the posture or inclination of the plane can be known, and therefore the relative posture or inclination of the reference plane body 30 with respect to the measuring instrument 20 can be obtained. In practice, the reference plane body 30 is fixed to the surface plate 10, so that the measuring device 20
The relative posture or inclination of the reference plane body 30 with respect to the reference plane body 30 indicates the posture or inclination of the measuring device 20 with respect to the reference plane body 30 or the surface plate 10.

Next, the measuring device 20 measures the positions of the three points P _{1 to} P ₃ on the surface of the reference spherical body 40. When the positions of the three points on the spherical surface are determined, the radius of the reference spherical body 40 is known in advance, so the position of the center of the reference spherical body 40 can be known. This state is described in detail in FIG. 2. If the spot light R is applied to the three points P _{1 to} P ₃ and the respective positions are obtained, those three points P _{1 to} P ₃ are present on the surface. A sphere with a specific radius will be uniquely determined. In this way, the position of the spherical center C of the reference spherical body 40 with respect to the measuring device 20 is obtained. This means that if the center of the sphere C of the reference spherical body 40 is the origin, the position of the measuring device 20 with respect to this origin C is obtained.

As a result, the accurate posture or inclination of the measuring device 20 with respect to the reference plane fixed to the surface plate 10, that is, the fixed surface, and the accurate position of the measuring device 20 with the spherical center C of the reference spherical body 40 as the origin. Is determined. In other words, the position and orientation of the measuring device 20 in the absolute coordinate system determined by the reference plane fixed on the stationary surface side and the origin are determined.

The measuring device 20 controls the position and posture inside the moving mechanism based on the traveling amount and the turning amount of the traveling column 24 and the revolving part 25, which are the moving mechanism, and controls the inside of the moving mechanism. The position of the measuring device 20 is detected by various sensors provided. By obtaining the deviation between the position and orientation information of the measuring instrument 20 in the coordinate system inside the moving mechanism, that is, the control coordinate system, and the position and orientation in the absolute coordinate system with the reference plane and the origin as the reference, Correct the control coordinate system on the moving mechanism side. That is, the origin of the control coordinate system and the information on the axial direction are corrected. Instead of physically or mechanically adjusting the installation of the moving mechanism itself, it is only necessary to modify the control coordinate system as internal information such as a control program incorporated in the control device of the moving mechanism. . If the control coordinate system on the moving mechanism side is correctly corrected, then the movement control of the measuring instrument 20 and the determination of the position and orientation can be performed using only the control coordinate system on the moving mechanism side.

The measuring operation on the object X to be measured by the measuring device 20 is carried out in the same manner as the ordinary measuring method for a three-dimensional shape. Specifically, with respect to the measurement point Q on the object to be measured X, the measuring device 2
By irradiating the spot light from 0 and capturing the reflected light, the distance from the measuring device 20 to the measuring point Q, that is, the relative position from the measuring device 20 can be known. The position and orientation of the measuring instrument 20 at this time are calculated based on the measured value at the measuring point Q, the moving amount of the measuring instrument 20 in the control coordinate system inside the moving mechanism, the control coordinate system and the absolute coordinate system. Since the correction is made by the deviation of, the accurate measurement result can always be obtained.

During measurement while moving the measuring device 20, errors in the amount of movement inside the moving mechanism may accumulate, resulting in deviation from the correct position and posture. . In such a case, the reference spherical body 40 and the reference plane body 3 described above are every time measurement is performed for a certain period of time.
If the coordinate system is corrected by measuring 0, the accumulation of errors due to the movement of the measuring device 20 can be eliminated.

If the object to be measured X is an object having only a flat surface, the reflected light of the spot light R emitted vertically downward from the measuring device 20 can be reliably captured by the measuring device 20. When the measurement object X has a complicated curved surface or inclined surface, it becomes difficult for the measuring device 20 facing vertically downward to capture reflected light.

Therefore, if the rotating arm 26 is swung according to the shape of the object to be measured X and the measuring device 20 is tilted to change the irradiation direction of the spot light R, the inclined surface or the vertical surface of the object to be measured X is changed. Also at the measurement point Q, the accurate position can be measured. As described above, when the measuring instrument 20 is tilted, if the coordinate system is corrected by the measurement of the reference spherical body 40 and the reference plane body 30 described above, it is possible to obtain an accurate result in the same manner as when the measuring instrument 20 is not tilted. Can measure. While changing the inclination of the measuring device 20 with respect to one DUT X depending on the location,
The three-dimensional shape of the entire measured object X can be accurately measured.

[0044]

According to the method and apparatus for measuring a three-dimensional shape of the present invention described above, the position and orientation of the non-contact type measuring means can be obtained by using the reference spherical body and the reference plane body. You can know exactly.

As a result, it is possible to easily correct the measurement error due to the installation error of the measuring means and its moving mechanism. Rather than physically correcting the position and orientation of the measuring means and the moving mechanism, it is only to correct the information of the coordinate system that determines the position and orientation, so the correction work is simple and highly accurate. It is possible.

In particular, even when the measuring means is tilted in accordance with the shape of the object to be measured, the position and orientation associated with the tilt can be easily corrected. Accurate measurement can be performed by moving the measurement point to the most preferable position and posture.

[Brief description of drawings]

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

FIG. 2 is a perspective view illustrating a method for measuring the position of a reference spherical body.

[Explanation of symbols]

10 surface plate (stationary surface) 20 measuring device (non-contact type measuring means) 22 to 26 moving mechanism 30 reference plane body 40 reference spherical body C center of sphere Q measurement point on object to be measured P _{1 to} P _{3 on} reference spherical body Measurement points S _{1 to} S ₃ Measurement points on the reference flat body X DUT

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

Claims (4)

[Claims] 1. A method for measuring a 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, and a reference spherical body which is previously fixed and With respect to at least three points on each surface of the reference flat body, the relative position with respect to the measuring means is measured by the measuring means, and the sphere of the reference spherical body with respect to the measuring means is measured from the position of each point on the reference spherical body. Find the relative position of the center,
Also, a three-dimensional characteristic characterized in that the relative posture of the reference plane body with respect to the measuring means is obtained from the position of each point on the reference plane body, and information on the position and posture of the measuring means is obtained based on these results. Shape measurement method. 2. The three-dimensional shape measuring method according to claim 1, wherein the stationary positions of the reference spherical body and / or the reference plane body can be changed. 3. The three-dimensional shape measuring method according to claim 1 or 2, wherein the non-contact measuring means is a means using a laser. 4. A tertiary comprising a stationary surface on which an object to be measured is stationary, and non-contact type measuring means which is movable with respect to the stationary surface and the object to be measured and which measures the position of each point on the object to be measured. In the original shape measuring apparatus, a three-dimensional shape including a reference spherical body and a reference plane body on the stationary surface side capable of measuring the positions of at least three points on the surface by the non-contact type measuring means. Measuring device.