JPH02311705A - Scanning type three-dimensional profile measuring apparatus - Google Patents

Abstract

PURPOSE:To measure three-dimensional values at a high speed during continuous scanning by latching the data at a moment when a non-contact type sensor which is made to scan continuously passes a measuring point, and adding the distance measured with the sensor to the Z coordinate. CONSTITUTION:A material to be measured 7 comprising an elastic body, a soft body and the like having a three-dimensional profile is mounted on a table 8 in an X-Y plane. A three- axis driving mechanism 1 is provided on the table 8. A non-contact length measuring sensor 3 is attached to the mechanism 1 so that the sensor 3 can be freely moved in three-dimensional direction. Then, a point which is separated from the tip of the sensor 3 by a specified distance Z0 is used as an original point. The sensor 3 is moved up and down in the direction Z in conformity with the change in surface shape of the material to be measured 7 within a specified range + or -DELTAz. That is the Z coordinate of the material to be measured 7 is obtained by adding the output of the sensor 3 in response to the up-and-down movement to the Z position of the mechanism 1. When the position of the sensor 3 which is made to scan with the mechanism 1 within the X-Y plane agrees with a specified measuring point, the three-dimensional coordinates representing the X-Y-Z position of the sensor 3 and the distance measured with the sensor 3 are latched. At this time, the mechanism 1 is not required to stop. The material to be measured having the complicated three-dimensional profile can be measured highly accurately in a short time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to a sensor that measures values in two directions of a workpiece placed on an xy plane table. X Sys of the object to be measured for each grid point of the pitch
This invention relates to a scanning type three-dimensional shape 71111 determination device for obtaining Z three-dimensional drift.

[Conventional technology]

A conventional example of such a three-dimensional shape measuring device is a device that combines a contact type touch sensor and a three-axis movement mechanism. In this device, while scanning the touch sensor within the xy plane, once the position of the touch sensor coincides with a measurement point consisting of grid points at a predetermined pitch, movement in the xy force direction is temporarily stopped. Then, the touch sensor is lowered in two directions, and the position of each axis of the three-axis moving mechanism when the tip of the sensor contacts the object to be measured is read to determine the three-dimensional coordinates of X5YsZ of one measurement point. Therefore, in this conventional example, it is necessary to repeatedly stop the movement of the sensor in the x and y force directions and lower the sensor in two directions for each measurement point, which has the disadvantage that continuous measurement cannot be performed and it takes time. Particularly, when the object to be measured has a complex shape such as a three-dimensional free-form surface such as an architectural design, the number of measurement points becomes enormous, and therefore a large amount of time is required for measurement.

[Problem to be solved by the invention]

This invention was made to deal with the above-mentioned circumstances,
Its purpose is to use a three-dimensional scanning method that can rapidly determine the x, y, and z values for each measurement point while continuously scanning each measurement point in the xy plane without stopping. An object of the present invention is to provide a shape measuring device.

[Means to solve the problem]

The scanning three-dimensional shape measuring device according to this invention is
A non-contact sensor that measures the distance to a fixed object in two directions, and a three-axis movement that continuously scans the sensor in the xyT' plane and moves the sensor in two directions so that the distance is constant. The three-dimensional coordinates indicating the x, y, z position of the sensor and the distance measured by the sensor when the position of the sensor in the xy plane scanned by the mechanism and the 3-axis movement mechanism coincides with a predetermined total of 71P1 points. and a latch circuit for capturing the data.

[Effect]

According to this invention, a non-contact type sensor is used, data is latched at the moment the continuously scanned sensor passes a measurement point, and the distance measured by the sensor is displayed on two coordinates of the three-axis movement mechanism. Since z (J) of the object to be measured is determined by addition, the x, y, and z values for each measurement point can be determined at high speed without stopping the constant x and y scanning of the sensor for each measurement point.

〔Example〕

An embodiment of the scanning three-dimensional shape measuring device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall configuration of the embodiment.

xy on which the object 7 having a three-dimensional shape is placed
A non-contact length measurement sensor 3 is attached to a three-axis moving mechanism 1 provided on a table 8 in a plane. As a result, the length measurement sensor 3 is movable in three directions: x and ySz.

Here, the maximum movement amount of the 3-axis movement mechanism 1 is 40 in the X direction.
00■, 2000IIIi in the y direction, 1 in the 112 direction
500IllI11, and the movement unit is 0.01mm5
The maximum travel speed is 188 mad/sec.

As shown in FIG. 2, the non-contact n1 length sensor 3 uses a point 1 dizo apart from its tip as its origin, and measures the displacement of the surface of the object to be measured 7 within a predetermined range (±Δ2) before and after the origin. It measures non-contact using light, etc., and outputs the measurement results as an electrical signal. In this way sensor 3
Since the measurement range of is limited, the three-axis moving mechanism 1 moves the length measurement sensor 3 up and down in two directions in accordance with changes in the surface shape of the object to be measured 7, as will be described later. As a result, the object to be measured 7
The surface of is always located within the n1 constant range of the length measurement sensor 3, and the two coordinates of the object to be measured are determined by adding the output of the sensor 3 to the two positions of the three-axis moving mechanism 1.

The output of the sensor 3 is input to an interface 5 via a detector amplifier 4. The interface 5 is connected to the positioning control device 2 of the three-axis moving mechanism 1 as well as to the data processing device 6. The interface 5 is connected to the positioning control device 2, detector amplifier 4, and data processing device 6 via cables. The positioning control device 2 controls the movement of the 3-axis movement mechanism 1 in each of the x, y, and z directions, and scans the non-contact length measurement sensor 3 in the xy plane. Connect the sensor 3 to the object to be measured 7 so that the output is always 0.
It is moved up and down in two directions along the surface shape.

Various types of non-contact length measurement sensor 3 can be considered, examples of which are shown in FIG. Laser light from a helium-neon (He-Ne) gas laser 30 outside the cylindrical housing 36 is reflected by a micromirror 47 provided on the optical axis 42, and is directed to the object to be measured via the convex lens 41 at the tip of the housing 36. 7 is irradiated. Focal length f of convex lens 41
l is the constant distance 20 in FIG. The position of the mirror 47 is not limited to this, and may be between the convex lens 41 and the object to be measured 7 or between the light shielding plate 44 and the convex lens 41.
In short, it is sufficient if the object to be measured 7 can be irradiated with laser light along the optical axis 42.

The light reflected from the object to be measured 7 passes through the convex lens 41 and the light shielding plate 4.
4 slits 46a, 46b, 46c.

The light enters CCD line sensors 50a, 50b, and 50c via cylindrical lenses 51a, 51b, and 51c. In FIG. 3, only the slit 46a, the cylindrical lens 51a, and the CCD line sensor 50a are shown for the sake of simplicity.
FIG. 4 shows a sectional view taken along the line AA' in FIG. 3, and FIG. 5 shows a sectional view taken along the line BB' in FIG. 3. In this way, the disk-shaped light shielding plate 44 has three directions perpendicular to the radial direction.
The slits 46a, 46b, 46c are arranged at equal intervals (120
(° interval). Behind the light shielding plate 44 are three cylindrical lenses 51a and 51b.

The generatrix of 51c is the slits 46a and 46b.

46c.

The cylindrical lenses 51 a, 5 l b, and 51 c are provided on a virtual plane 45 parallel to the light shielding plate 44, and the distance between the virtual plane 45 and the convex lens 41 is fl, and the virtual plane 45
The distance between the rear end of the housing 36 and the rear end of the housing 36 is I2 (the focal length of the cylindrical lenses 51a, 51b, and 51c is 1ift).

At the rear end of the housing 36 are three CCD line sensors 50a, 50b facing in the radial direction.

50c is provided. Line sensor 50a.

The outputs of 50b and 50c are supplied to the data processing device 6,
The displacement Δzl of the object to be measured 7 is determined.

FIG. 6 shows the relationship among the slit 46a, cylindrical lens 51a, and line sensor 50a. The line sensor 50a is provided in a vertical plane 60a perpendicular to the generatrix 52a of the cylindrical lens 51a. Slit 46a1 Generating line 5 of cylindrical lens 51a
2a is provided in a vertical plane 60a I: a horizontal plane 62b orthogonal to each other. Let the distance between the horizontal plane 62b and the optical axis 42 be a. The center of the line sensor 50a is within the horizontal 11j62b. Although not shown, line sensors 50b, 50
c is similarly provided.

Next, the distance measurement principle of the length measurement sensor 3 will be explained. First, since the slit 46a is provided on the front surface of the cylindrical lens 51a, the light rays incident on the cylindrical lens 51a can be considered to be parallel rays, as shown in FIG. For this reason, the seventh
The following relationship can be obtained from the figure.

x-I2 ・tan θ −(1) Also, the following relationship can be obtained from FIG.

tanθ-y/(fl+z2) = (y-a)/fl...(2) Convex lens 41a
The following relationship is obtained by the action of .

fl”−Δzl −z2 − (3)
The following relationships can be obtained from equations (1)2 to (3).

X-a-I2・Δz1/f I2- (4) (4)
The formula shows that the displacement Δzl of the object to be measured can be determined from the incident position X of the beam spot on the line sensor 50a. The incident position X can be determined from the address of the element where the output of the line sensor 50a peaks. A line sensor 50a with 7 μm x 2059 elements is used, a-20+n+n, f 1 =70 mm,
When f 2-150 +u+ is closed, the resolution is 11.
One displacement can be measured in the range of ±11.7a++a (Δzl) at 4μm.

In this way, according to this sensor 3, the displacement can be determined only from the position of the incident light, so the measured value does not depend on the intensity of the incident light or changes in the amount of light, and it is possible to determine the displacement of the surface of the object to be measured. Reproducible APL determination results can be obtained that are not affected by reflectance, roughness, curvature, inclination, or external interference signals.

Since it is a non-contact/1111 constant, it can also be used to measure the displacement of intermediate I1 bodies, soft bodies, objects in high-temperature containers, etc., which are difficult to measure with contact iPI constants. Further, since parallel light rays are emitted on the optical axis of the lens system and reflected light is picked up near the optical axis, no blind spot of 4Pj is generated. Furthermore, since the detection of the incident position of the reflected light by the line sensor is based on the premise that the intensity distribution of the light is axially symmetrical with respect to the optical axis of the lens, it is difficult to detect the incident position of the reflected light. not vertical,
As a result, even if the light intensity distribution is asymmetric with respect to the optical axis, the measurement results are not affected.

FIG. 9 is a circuit diagram of the embodiment. The rotation of the X-axis, y-axis, and Z-axis servo motors 223, 213, and 203 that move the 3-axis moving mechanism 1 in the Z direction by X% Y%, that is, the rotation of the 3-axis moving mechanism 1 by X%! The current value of /%Z is detected by feedback sensor 224.214.204. Output f xi of feedback sensor 224, 214, 204
, f yl.

fzl is supplied to pulse branch circuits 504, 503, and 502. First outputs f x2 , f y2 , f z2 from the pulse branch circuits 504, 503° 502
is sent to the adder 225°215. as a feedback pulse.
205 and the second output f x
3, fy3, and fz3 are supplied to current position counters 505, 506, and 507.

On the other hand, the signal from the data processing device 6 is transmitted to the arithmetic control circuit 23.
1. Position command pulse f via pulse distribution circuit 230
Adder 2 as xo, fyo, fzo
25. The position command pulses f xo , f yo , f zo are supplied to the other input terminal of 215 and 205.
Feedback pulses f x2 , f y2 from
, f z2 are subtracted. Note that the position command pulse f
From zo, a pulse signal [Δ
2 is subtracted by adder 206. Adder 225.2
The output of 15.205 is the position control circuit 221.211.2
01 and speed control circuits 222, 212, and 202 in series, respectively, to the servo motors 223, 213, and 203.

On the other hand, the outputs f x3 , f y3 , f z3 of the current position counters 505, 506° 507 are supplied to the latch counters 513, 514, and 515, and the output Δzl of the detector amplifier 4 is supplied to the latch counter 516. Coordinate data x of the next measurement point output from the parallel input/output circuit 520 connected to the data processing device 6,
1. yi is the measurement point counter 508. ．． 509. A comparator 510 compares the output of the current position counter 505 and the output of the all one point counter 508, and a comparator 511 compares the output of the current position counter 506 and the output of the measurement point counter 509. Comparator 510°511
outputs an “H” level coincidence signal when the two forces match. The outputs of the comparators 510 and 511 are connected to the AND gate 51
Latch counter 513, 514, 515, 5 through 2
16, is supplied to the parallel input/output circuit 520 as a latch command signal.

That is, the latch command signal is generated every time the position of the length measurement sensor 3 in the xy plane coincides with a predetermined measurement point. Output X+ of latch counters 513, 514, 515゜516
Y+z+Δ2 is supplied to parallel input/output circuit 520.

The operation of the circuit shown in FIG. 9 will be explained. First, the data processing device 6 determines the xy coordinates of measurement points consisting of grid points at a predetermined pitch. Based on the xy coordinates of each measurement point, the parallel input/output circuit 520 outputs the xy coordinates xi, yi of the next measurement point to the measurement point counters 508 and 509. Further, the arithmetic and control unit 231 generates a position command pulse fxo for causing the three-axis moving mechanism 1 to perform constant x-y scanning based on the pitch of measurement points, measurement range, etc.

fyo is determined and output via the pulse distribution circuit 230.

On the other hand, the arithmetic and control unit 231 obtains a position command pulse fzo that will cause the position of the three-axis moving mechanism 1 in two directions to be 20,
It is output via the pulse distribution circuit 230. Detector
The output voltage signal Δzl of the amplifier 4 is converted into a pulse fΔ2 with a frequency corresponding to the voltage by a displacement/frequency conversion circuit 501, and is added to the position command pulse fzo. The displacement/frequency conversion circuit 501 does not respond to voltages below ±ε0, but responds to voltages higher than that and generates pulses with a frequency proportional to the voltage. Therefore, the servo controller 203 is controlled so that the distance from the tip of the sensor 3 to the object 7 to be measured is always within a certain distance of 20±ε0, and the output of the sensor 3 is always zero.

As a result, the 3-axis moving mechanism 1 automatically moves up and down along the surface shape of the object to be measured 7, and the surface of the object to be measured 7 is always located within the distance measurement range (±Δ2) of the length measurement sensor 3. become.

Current value f x3 of the xy coordinates of the 3-axis moving mechanism 1 obtained by the feedback sensor 224° 214 during xy constant scanning
, f y3 is the xy coordinate xi of the next measurement point.

If they match Yi, the current position of the three-axis moving mechanism 1 and the output of the length measurement sensor 3 are latched. At this time, the 3-axis moving mechanism 1
movement need not be stopped. After this, the parallel input/output circuit 520 updates the coordinates of a total of 7 #1 points and reads the latch data. The binary value of the object to be measured 7 is obtained by adding the output Δz1 of the length measurement sensor 3 to the binary value of the three-axis moving mechanism 1. By repeating the above operations, three-dimensional coordinates of all measurement points can be obtained.

According to this embodiment, the three-dimensional shape can be measured in a short time and with high accuracy even for an object to be measured that has a complicated three-dimensional shape and requires a huge number of points (111 points in total).

When measuring at a pitch of 5 tnm while performing uniaxial scanning at a speed of f30 mm/sec, an accuracy of ±0.05 mm was obtained.

〔Effect of the invention〕

As explained above, according to the present invention, there is a non-contact sensor that measures the distance to the object to be measured in two directions by 1lllJ, and the sensor scans two-dimensionally within the xy plane, and the distance is kept constant. A 3-axis movement mechanism that moves the sensor in two directions so that x of the sensor is scanned by the 3-axis movement mechanism.
By providing a latch circuit that captures the three-dimensional coordinates indicating the x, ySz position of the sensor and the distance measured by the sensor when the y horizontal city position coincides with a predetermined measurement point, A scanning three-dimensional shape measuring device is provided that rapidly obtains x, y, and z values for each measurement point while continuously scanning xy scans of a sensor without stopping.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an embodiment of the scanning three-dimensional shape measuring device according to the present invention, Fig. 2 is a diagram showing the measurement range of the length measurement sensor, and Figs. 3 to 6 show an example of the length measurement sensor. Figure shown, 7th
FIG. 8 is a diagram explaining the measurement principle of the DJ length sensor, and FIG. 9 is a circuit diagram of an embodiment. 1... 3-axis movement mechanism, 2... positioning control device, 3...
・・Non-contact 1jlllJ length sensor, 4...detector・
Amplifier, 5... Interface, 6... Data processing device, 7... Subject A-j constant. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 4 Figure 5

Claims (1)

[Claims] A non-contact sensor that measures the distance in the z direction to the object to be measured, and a 3-axis movement that continuously scans the sensor in the xy plane and moves the sensor in the z direction so that the distance is constant. mechanism, and three-dimensional coordinates indicating the x, y, z position of the sensor when the position in the xy plane of the sensor being scanned by the 3-axis movement mechanism matches a predetermined measurement point, and the position measured by the sensor. A scanning three-dimensional shape measuring device comprising a distance and a means for taking in the distance.