JPS6080705A - Measuring method of three-dimensional object - Google Patents

Abstract

PURPOSE:To improve measuring accuracy by moving a distance detector which is movable in the direction intersecting with the turning axial line of an object to be measured while maintaining the specified distance between said object and detector by the reflected light of the light irradiated from the detector to the surface of the object and determining the coordinates of the measuring point. CONSTITUTION:A freely vertically movable Z-shaft 13 and a revolving shaft 14 provided with a freely rotatable angle detector 49 are respectively supported on both sides of a base 11 and horizontal and rotary tables 53, 16 are respectively attached to the shafts 13, 14. A distance detector 54 of a non-contact type which is moved forward and backward by a positioning device 56 in the direction orthogonal with the turning axial line O of the table 16 and a position detector 55 for said detector are provided to the table 53. The beam from a laser light source 61 is irradiated via a splitter 62 and an objective lens 63 to an object W to be measured and the light reflected from the object is bent by the splitter 62 and is detected by the photodetecting surface 65 of a photodiode. The detector 54 is moved until the output therefrom is made constant and the position of the detector is determined. The coordinates on the surface of the object W are thus determined.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measurement method for measuring three-dimensional objects in a non-contact manner.

In general, for measuring the dimensions and shape of objects to be measured,
So-called three-dimensional object measurement, in which a touch signal probe is configured to be movable in two or three dimensions, and the dimensions and shape of the object to be measured are measured from the amount of displacement of the probe when it comes into contact with the object to be measured. The device is known.

Conventionally, in this type of device, the probe is brought into contact with the object to be measured, which not only tends to cause errors due to the contact force and contact posture, but also requires the probe to have return-to-origin, omnidirectionality, and overstroke tolerance. As a result of sexual and other functions being considered,
It has to be expensive. Furthermore, if the object to be measured is a relatively elastic material such as a plastic member, measurement may not be possible.

This requires a non-contact measuring device. Optical and electromagnetic methods are conceivable, but we have yet to see anything of practical value emerge. The reason for this is thought to be the result of unstable characteristics with respect to directionality and strokes.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for measuring three-dimensional objects that eliminates the drawbacks of the conventional measuring methods and enables highly efficient and highly accurate measurement.

Therefore, in the present invention, while the object to be measured is rotated, a light beam is irradiated onto the surface of the object to be measured from a non-contact distance detector that can be moved in a direction intersecting the axis of rotation of the object to be measured. The distance detector is moved using the reflected light from the surface of the object to be measured so that the distance from the distance detector to the surface of the object to be measured is constant, and when the object to be measured stops, the initial position of the distance detector is The above object is achieved by determining the coordinates of the measurement point of the object from the amount of movement relative to the object.

Therefore, first, the measurement principle of the present invention will be explained. First, as shown in FIG. 1, the object to be measured W is placed on a rotating disk E, and the laser beam projector/receiver G is placed at a position B that is a distance A away from the center of rotation O of the rotating disk E. Here, distance A
is the focal length of the laser beam of the laser beam emitter/receiver G.

In this state, while irradiating the laser beam from the laser beam emitter/receiver G to the measurement point P+ of the object W, the laser beam emitter/receiver G is rotated around the center so that the focus of the laser beam is on the measurement point P1. When the laser beam emitter/receiver G is moved in the direction intersecting 0, the distance OPI from the rotation center 0 to the measurement point PI of the object W is moved relative to the position B.
is moved to position C, which is located to the left.

Next, when the rotating disk E is rotated by an angle θ1 in the direction indicated by the arrow in the figure, a measurement point P2 is located at the position of the measurement point P1. Here, if the laser beam emitter/receiver G is moved so that the focal point of the laser beam from the laser beam emitter/receiver G is focused on the measurement point P2.

The laser beam projector/receiver G is moved by a distance 1 down 2 from the rotation center 0 to the measurement point P2 with respect to the above position IB.

In this way, the rotating disk E is rotated by a predetermined angle,
Each measurement point P+ of the object to be measured W at each rotation stop position
, p2. When the laser beam emitter/receiver G is moved so that the laser beam focuses on Pg and P4 in order,
The distance from the rotation center 0 to the laser beam emitter/receiver G is:
(A+OF+).

(A+ is 72), (A+OP9), (A+♂〒4)...
・Changes. In other words, the moving distance of the laser beam projector/receiver G from the position B is from the rotation center 0 to each measurement point P+, P2, Pg, P4, . . . on the object W to be measured.

From this, the rotating disk E is rotated by a predetermined angle and the laser beam emitter/receiver G is moved so that the laser beam is sequentially focused on the surface of the object W to be measured, and the rotating disk E is then moved. By calculating the angle of
a, P4, . . . can be expressed in polar coordinates with the rotation center O as the origin.

Here, each measurement point P+, P2. The polar coordinates of Pa, P4, . . . can be converted to orthogonal coordinates. For example, the orthogonal coordinates y2 is as shown in Figure 2,
If OP 2 = r, then X2-0xa -rcos
θ+ ... (1) y2≠03'*+rBlnθ-・
...(2) In this way, each measurement point P+, P
2°Pa, P<... can also be expressed as orthogonal coordinates.

Therefore, the axis passing through the center of rotation O in Figure 1 and perpendicular to the plane of the paper is Z
If the laser beam emitter/receiver G is moved by a fixed amount in the Z-axis direction, and the two-dimensional shape of the object W to be measured is expressed as polar coordinates or orthogonal coordinates at each position in the Z-axis direction, The three-dimensional shape of the object W to be measured can be easily determined.

Next, an embodiment of a three-dimensional object measuring device implementing the measuring method of the present invention will be described based on FIGS. 3 to 9.

FIG. 3 shows the external appearance of the three-dimensional object measuring device of this embodiment.

In the same figure, a vertical Z-axis 13 is provided on the upper side of the base 11 via a pole screw receiver 12 so as to be vertically movable up and down, and the Z@h13 is provided on the other side of the upper surface. The lower part of the rotating shaft 14 parallel to the Φ-center axis is rotatably supported. A rotary table 16 for mounting and fixing the object W to be measured is integrally and horizontally provided at the upper end of the rotary shaft 14, and a perfect circular ring 17 is mounted below the rotary table 16. A vertical deflection detector 18 for detecting vertical deflection of the rotary table 16 is opposed to the lower surface side of the rotary table 16, and a vertical deflection detector 18 for detecting vertical deflection of the rotary table 16 is disposed on the outer periphery of the perfect circular ring 17. A core runout detector that detects core runout! 9 is facing.

As shown in FIG. 4, the vertical vibration detector 18 is configured such that a laser beam emitted from a laser light source 21 is bent at a right angle by a beam splitter 23 from a collimator lens 22, passes through an objective lens 24, and is directed to the lower surface of a rotary table 16. The reflected light from the lower surface of the six-turn table 16, which is to be irradiated, passes through the objective lens 24 and beam splitter 23, is condensed by a condenser lens 25, and is then received by a photodiode 26. Here, if the focus of the laser beam does not match the lower surface of the rotary table 16 and moves away from or lags behind the lower surface of the rotary table 16, for example,
A focusing signal FC5I is output from the signal processing circuit 27. This focusing signal FC3+ is sent to amplifier 2.
After being amplified via f-8, the signal is input to a servo mechanism 29 that moves the entire optical system in the vertical direction. As a result, the entire optical system is moved in the vertical direction until the focus of the laser beam is properly positioned on the lower surface of the rotary table 16. Therefore, when the rotary table 16 swings vertically during rotation, the amount of vertical swing is detected as the amount of movement of the entire optical system.

Further, as shown in FIG. 5, the center runout detector 19 causes the laser beam emitted from the laser light source 31 to be beam-splitting from the collimator lens 32.

The beam is bent at a right angle at a bend 33, and is irradiated onto the outer circumferential surface of the perfect circular ring 17 through an objective lens 34. The reflected light from the outer peripheral surface of the perfect circular ring 17 passes through the objective lens 34 and the beam splitter 33, and then enters the condenser lens 35.
After the light is collected by the photodiode 36, the light is received by the photodiode 36.

Here, if the focus of the laser beam does not coincide with the outer circumferential surface of the perfect circular ring 17 and moves away or lags behind the outer circumferential surface of the perfect circular ring 17, the focusing signal F CS2 is output from the signal processing circuit 37. Output.

The focusing signal F CS 2 is amplified via an amplifier 38 and then input to a servo mechanism 39 that moves the entire optical system in the horizontal direction. As a result, the entire optical system is moved in the horizontal direction until the focus of the laser beam is correctly positioned on the outer peripheral surface of the perfect circular ring 17. Therefore, when the one-turn table 16 causes center runout during rotation, the amount of center runout is detected as the amount of movement of the entire optical system.

Further, a motor 42 serving as a rotational drive device for rotating the rotating shaft 14 is connected to the lower end of the rotating shaft 14 via a gear mechanism 41 .

An angle detector 49 that detects the rotational angular position of the rotary table 16 is connected via a gear mechanism 43. Now, if we consider the size of the object W to be measured with a radius of 500 mm centered on the rotation axis O of the rotary table 16, that is, when measuring the outer circumferential shape of the object W with a diameter of 1 m with an accuracy of IILm, one rotation is For one rotation of table 1B, (1mX
w) I have to know the number of 3141600 points for 71gm wheels. For this reason, in this embodiment, 1 revolution per revolution
An incremental rotary encoder 44 that generates 0,000 pulses is used, and the gear mechanism 43 is configured so that one rotation of the rotary table 16 generates 400 rotations, that is, 4,000,000 pulses.

In addition, in order to detect the origin in the rotational direction of the rotary table 16 and to prevent reading errors, one pulse is generated every time the incremental rotary encoder 44 makes one revolution, that is, every time lOθ00 pulses are generated, and when 400 pulses are generated, the rotation starts. For example, as shown in FIG.
The pulses generated once each time 4 rotates are input to the modulator 46, respectively. The modulator 45 modulates the frequency 1 with pulses generated by the incremental rotary encoder 44, while the modulator 46 modulates the frequency F2 with the incremental rotary encoder 44 Irff1lIi; This modulator 45
The output of the modulator 46 is inputted to a counter 47, and the rotation angle position of the rotary table 16 is determined from the count number of the counter 47. Therefore, for example modulator 4
If the output of the modulator 46 is 8I1199 due to a malfunction, the count is incorrect, so the motor 42 that applies rotational force to the rotary table 16 is stopped and the measurement is performed again. The reason for modulating the frequencies F+ and F2 with the pulses of the rotary encoder is that one frequency Fl, F2 is modulated by the pulses of the rotary encoder.
This is to prevent malfunctions in the second tuning circuit.

On the other hand, the Z-axis 13 is provided with a lifting device 51 at its lower end that raises and lowers the Z-axis 13 in the vertical direction (Z-axis direction), and also moves the vertical position of the Z-axis 13 along the Z-axis 13. A height detector 52 such as a linear encoder is provided to detect the height. Furthermore, a horizontal table 53 is horizontally attached to approximately the vertical center of the Z-axis 13 . The horizontal table 53 includes a distance detector 54 that irradiates the surface of the object W with a laser beam and detects the distance to the object W in a non-contact manner using reflected light from the surface of the object W.
The distance detector 54 adjusts the distance to the surface of the object to be measured W to be constant according to the output signal from the distance detector 54.
A positioning device 5 that moves the rotary table 16 forward and backward in a direction perpendicular to the rotation axis O of the rotary table 16 (for example, in the Z-axis direction).
A position detector 55 such as a linear encoder for detecting the moving position of the distance detector 6 and the distance detector 54 is provided, respectively.

As shown in FIG. 7, the distance detector 54 is configured such that a laser beam from a laser light source 61 passes straight through a beam splitter 62, passes through an objective lens 63, and is irradiated onto the object W to be measured. The reflected light from the object W to be measured passes through an objective lens 63, is bent at a right angle by a beam splitter 62, passes through a cylindrical lens 64, and is received by a photodiode light receiving surface 65.

Now, if the distance between the objective lens 63 and the object W to be measured matches the focal length A shown in FIG. ), a light-receiving element A+ that constitutes the photodiode light-receiving surface 65;
A2. B+ and B2 appear circularly, and the outputs of all amplifiers 67 become zero. If the distance between the objective lens 63 and the object to be measured W is larger than the focal length A, that is, the object to be measured W
When the distance between the objective lens 63 and the objective lens 63 is long, the distance shown in FIG.
As shown in FIG. 2, since the image is focused only on the light receiving elements Bl and B2, the output of the amplifier 67 becomes -Vl. This output -v■
is input to the positioning device 56 configured by a servo mechanism or the like, the positioning device M56 causes the distance detector 54 to cross the rotation axis 0 of the rotary table 16 at right angles until the output -Vl becomes zero. is moved in the axial direction, and its
The axial position is detected by a position detector 55.

The output from the position detector 55 is as shown in FIG.
It is input to one input terminal of an adder/subtractor 72 of an arithmetic processing device 71. The adder/subtractor 72 corrects the output from the position detector 55 with the output from the center runout detector 19, and (X) of the distance detector 54 is input to a synthesis circuit 73, which corrects the output from the angle detector 49. This is combined with the rotation angle data (θ) of the rotary table 16 detected at . The composite output (x, θ) from the composite circuit 73 is input to the next composite circuit 74,
It is combined with the output data from the adder/subtractor 75. The adder/subtractor 75 corrects the output from the height detector 52 with the output from the vertical shake detector 18 to calculate the height of the Z-axis 13, that is, the height data (0) of the distance detector 54. . Therefore, the height data (θ) of the distance detector 54 and the synthesis circuit 7
The synthesized output (x, θ) from 3, that is, the position data (X) of the distance detector 54 and the rotation angle data (θ) of the rotary table 16 are synthesized by a synthesis circuit 74 and then input to a computer 75. The computer 75 performs predetermined calculations according to commands given from the operation panel 77 via the controller 76, stores the results in the floppy disk 78, and outputs them to the output device 79. The output device 79 is, for example, a plotter, recorder, CRT, etc., and displays the data obtained from the computer 74 as a 2.3-dimensional image, orthogonal coordinates, polar coordinates, etc.

Next, the operation of this embodiment will be explained. First, the object W to be measured is set on the upper surface of the rotary table 16, and then the motor 42 is driven to rotate the rotary table 16 via the rotary shaft 14. Then, the rotation angle data (θ) of the rotary table 16 is detected by the angle detector 49 and then provided to the arithmetic processing unit 71.

On the other hand, when the rotary table 16 rotates, the focus of the laser beam from the distance detector 54 changes from the rotation axis O of the rotary table 16 to each measurement point on the target object W. The distance detector 54 is moved in the X-axis direction so as to be located on each measurement point, and after each movement amount is detected by the position detector 55, the adder/subtractor 72 of the arithmetic processing unit W71
is input to. At the same time, the amount of center runout of the rotating shaft 14 detected by the center runout detector 19 is input to the adder/subtractor 72 . As a result, in the adder/subtractor 72, the position detector 55
The position data (Z) given from
, the rotary table 1 detected by the angle detector 49
It is combined with the rotation angle data (θ) of No. 6.

The combined output (x, θ) from the combining circuit 73 is input to the next combining circuit 74, where it is combined with the output from the adder/subtractor 75. Since the data from the height detector 52 and the vertical vibration detector 18 are respectively input to the adder/subtracter 75, the output from the adder/subtracter 75, that is, the height data (Z) in the X-axis direction and the composite (Xlθ , Z) and computer 75
is input to. Thereby, the computer 75 calculates the dimensions of the surface of the object W from the rotation axis 0 from the given position data (X,) and the dimensions of the surface of the object W from the rotary table 16 from the height data (Z). Determine the height and the circumferential position of the surface of the object W from the rotation angle data (θ), respectively.
The results are stored in the floppy disk 77 and displayed on the output device 79.

In this way, the horizontal cross-sectional shape of the object to be measured W is measured.
By repeating this in the X-axis direction, the three-dimensional shape of the object W can be measured. For example, in addition to two-dimensional and three-dimensional shapes, dimensions of necessary parts, plane area, cubic volume, center position,
Or the hole position, hole depth, hole diameter on the surface of the object to be measured,
It is possible to measure the shape of a protrusion, surface roughness, etc., and display them together with the measured values as a two-dimensional or three-dimensional image.

Therefore, according to this embodiment, measurement can be performed without using a contactor, that is, without applying any physical external force to the object to be measured W, so that measurement can be performed at extremely high speed and with high accuracy. By the way, assuming that the rotation speed of the rotary table 16 is 15 seconds per rotation.

The XY plane can be measured in 15 seconds, and if 100 layers are measured in the X-axis direction, the total three-dimensional measurement can be performed at a speed of 1500-25 minutes, and the measured values can be measured with an accuracy of less than lILm.

Further, the position data (X) of the distance detector 54 is corrected by the amount of center runout of the center runout detector 19, while the height data (Z) of the distance detector 54 is corrected by the amount of vertical runout of the vertical runout detector 18. Therefore, errors in machining or assembly will not affect the measured values, and therefore highly accurate measurements can be expected.

Further, since the position data (X) of the distance detector 54, the rotation angle data (θ) of the rotary table 16, and the height data (Z) of the distance detector 54 are processed by the computer 75, the computer 75 In addition to the 2D and 3D image shapes, the necessary dimensions, flat area, cubic volume,
Center position or hole position on the surface of the object to be measured, hole depth,
The diameter of holes, the shape of protrusions, and even surface roughness can be easily measured, and the measurement results can also be displayed as two-dimensional or three-dimensional images.

In the above implementation, the distance detector 54 irradiates the surface of the object W with a laser beam, and the reflected light from the surface of the object W forms an image on the photodiode light receiving surface 65. Although the image-forming optical detector is used to detect the distance to the surface, the distance detector 54 irradiates the surface of the object W with a laser beam of a certain shape, and detects the reflected light from the surface of the object W. A triangulation type optical detector that detects the distance to the surface of the object to be measured W based on the reflection angle of the object W may be used.

Further, in the above embodiment, in the initial state, the distance detector 54 is arranged at a position away from the rotation axis 0 of the rotary table 16 by the focal length A, so that the focus of the laser beam from the distance detector 54 is on the rotary table 16. Although the focal point of the laser beam from the distance detector 54 does not necessarily have to coincide with the rotation axis 0 of the rotary table 16, in this case, To determine the measurement point on the surface of the object W, the amount of movement of the distance detector 54 from the initial position may be added to an arbitrarily set focal position.

Further, in the above embodiment, the rotary table 16 is rotated by a predetermined angle, and the distance detector 5 is detected at each rotation stop position.
4 to the surface of the object to be measured W is measured by moving the distance detector 54 so that the distance from the surface of the object W to be measured is constant, but the measurement may be performed while continuously rotating the rotary table 16.

In this way, faster measurement can be expected.

Furthermore, in the above embodiment, the rotation axis of the rotary table 16 is 0.
A distance detector 54 that can advance and retreat in a direction perpendicular to the
In addition to this distance detector 54, a distance detector that can be raised and lowered in a direction parallel to the rotation axis 0 is moved in a direction perpendicular to the rotation axis 0. By arranging them freely, any three-dimensional shape can be measured.

As described above, according to the present invention, it is possible to provide a method for measuring a three-dimensional object that eliminates the drawbacks of conventional measuring methods and enables efficient and highly accurate measurement.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing the measurement principle of the present invention, Fig. 52 is an explanatory diagram for converting polar coordinates to rectangular coordinates, and Fig. 3 is an example of a three-dimensional object measuring machine implementing the measuring method of the present invention. FIG. 4 is an explanatory diagram showing the vertical runout detector, FIG. 5 is an explanatory diagram showing the center runout detector, FIG. 6 is an explanatory diagram showing the angle detector, and FIG. 7 is an explanatory diagram showing the distance detector. FIGS. 8(A) and 8(B) are explanatory diagrams showing the photodiode light receiving surface,
FIG. 77 is a block diagram showing the arithmetic processing device. W...Object to be measured, 54...Distance detector. Agent Patent attorney Minoru Kinoshita (and 1 other person) Figure 1 Figure 2 OX2 XOX Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 (A) (8)

Claims (1)

[Claims] (1) While rotating the object to be measured, a non-contact distance detector that can move in a direction intersecting the rotational axis of the object irradiates a light beam onto the surface of the object. The distance detector is moved using reflected light from the surface so that the distance from the distance detector to the surface of the object to be measured is constant, and the object to be measured is measured from the amount of movement of the distance detector from the initial position. A method for measuring three-dimensional objects characterized by determining the coordinates of a location.