JPH06300539A - Three-dimensional shape measurement device - Google Patents

Abstract

PURPOSE:To provide a device having an intensity adjustment means capable of obtaining the proper intensity of a bundle of diffused rays at all times, regardless of the surface color or surface state of a measurement object, or the incident angle or the like of a measurement ray bundle. CONSTITUTION:This device is composed of a measurement ray bundle emission means A for emitting a spot-like measurement ray bundle toward a measurement object 2, a diffused ray bundle detection means B for detecting a bundle of diffused rays from the surface of the object 2, and a signal processing means C for operating and deriving the three-dimensional shape of the object 2 on the basis of data detected with the means B. In addition, the device is equipped with an intensity measurement means D for adjusting the intensity of the measurement ray bundle on the basis of a ratio of the intensity detected with the means B to the intensity of the measurement ray bundle, so that the intensity detected with the means B falls within the predetermined range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a measuring beam bundle irradiating means for irradiating a measuring beam bundle in the form of a slit or a spot toward an object to be measured, and a beam bundle scattered from the surface of the object to be measured. Regarding a three-dimensional shape measuring device comprising a scattered light flux detection means and signal processing means for calculating and deriving the three-dimensional shape of the measurement object based on detection data by the scattered light flux detection means, for example, a spot A device that scans a circular laser beam bundle onto the measurement target, measures the scattered light flux from the measurement target with a CCD image sensor, etc., and specifies the shape of the measurement target from the detected position data. Input device for CAD data that inputs the external shape from the model of various types of designed products and finishes the final design drawing, and input device for 3D image materials used for education and sales , Medical diagnostic equipment, or relates to a three-dimensional shape measuring apparatus used as a visual sensor of a robot.

[0002]

2. Description of the Related Art A three-dimensional shape measuring apparatus of this type detects a minute light flux incident on a scattered light flux detecting means out of scattered light flux from an object to be measured. It was necessary to secure the intensity of the measurement light flux so as to obtain it. For example, a spot-like laser beam flux is scanned on the measurement target, and the scattered light flux from the measurement target is transferred to the CCD.
In the case of measuring with an image sensor and detecting the position, if the scattered light flux intensity is too strong, the output of multiple adjacent pixels of the CCD image sensor is saturated, and the true position cannot be detected, or the scattered light flux is not detected. CCD is too weak
The output of the image sensor becomes so small that the S / N ratio is lowered, and the true position cannot be accurately detected. Therefore, the detection intensity by the scattered light flux detection means is within a predetermined range,
For example, when a CCD image sensor is used as a detection element, if the detection intensity is small so that it falls within a certain range where saturation is not reached and the S / N ratio does not decrease, the intensity of the measurement light flux is small. Is increased at a constant rate, and if the detected intensity is large, the intensity of the measurement light beam is reduced at a constant rate.
A strength adjusting means for performing so-called proportional control was provided.

[0003]

However, the above-mentioned intensity adjusting means according to the prior art does not consider the surface color or surface state of the object to be measured, the incident angle of the measuring light beam bundle, or the like, and has a uniform scattering characteristic. Assuming that (the measured light flux intensity and the scattered light flux intensity are in a proportional relationship), the intensity of the measured light flux is proportionally controlled at a constant ratio.
Depending on the surface color and surface state of the object to be measured, the incident angle of the measurement light flux, etc., the intensity of the light flux incident on the scattered light flux detection means may differ greatly from the expected value. Has a problem that accurate detection becomes impossible. For example, the intensity control means is the surface color "
When the intensity of the measurement light flux is adjusted at a constant rate based on the "black" measurement target, when a measurement target with a "white" surface color is measured, "white" is better than "black" Since the reflection coefficient is large, overcorrection occurs, and conversely, when the intensity adjusting means intensity-adjusts the measurement light flux at a constant ratio based on the measurement object with the surface color "white", the surface color is When a "black" object is measured, the correction coefficient is insufficient because "black" has a smaller reflection coefficient than "white." The object of the present invention is to eliminate the above-mentioned conventional drawbacks. , Regardless of the surface color or surface condition of the object to be measured, or the incident angle of the measurement light bundle,
It is an object of the present invention to provide a three-dimensional shape measuring apparatus provided with an intensity adjusting means that can always obtain an appropriate scattered light flux intensity.

[0004]

In order to achieve this object, the characteristic configuration of the three-dimensional shape measuring apparatus according to the present invention is based on the ratio between the intensity detected by the scattered light flux detecting means and the intensity of the measured light flux at that time. The point is that intensity adjusting means for adjusting the intensity of the measurement light flux is provided so that the intensity detected by the scattered light flux detection means falls within a predetermined range. In the above-mentioned configuration, the intensity adjusting means, based on the ratio of the intensity of the measurement light flux at that time and the detection intensity by the scattered light flux detection means in the vicinity of the measurement target location for the measurement target, It is preferable to control the strength. Further, the intensity adjusting means adjusts the intensity of the measurement light flux based on the ratio of the intensity of the measurement light flux at that time to the intensity detected by the scattered light flux detection means at the measurement object position with respect to the measurement object. Is preferred.

[0005]

When the surface color or surface condition of the object to be measured, or the incident angle of the measuring light flux is constant, the ratio of the intensity detected by the scattered light flux detecting means and the intensity of the measuring light flux at that time is constant. Focusing on, the intensity adjusting means, based on the ratio of the intensity detected by the scattered light flux detecting means and the intensity of the measured light flux at that time, the intensity of the measuring light flux detected by the scattered light flux detecting means falls within a predetermined range. The intensity of is adjusted.
In this case, in the vicinity of the measurement target location with respect to the measurement target, the surface color or surface state of the measurement target, or the incident angle of the measurement light flux is often almost constant. By adjusting the intensity of the measurement light flux this time based on the ratio of the intensity of the scattered light flux detection means in the vicinity of the target location and the intensity of the measurement light flux at that time, the measurement target location can be continuously changed to a high speed. Can be measured. Furthermore, in the case where the surface color or surface state of the measurement target, or the incident angle of the measurement light flux changes rapidly in the vicinity of the measurement target location for the measurement target, the same measurement target of the measurement target is measured. Based on the ratio of the intensity of the measured light flux at that point by the scattered light flux detection means and the intensity of the measurement light flux, if the intensity of the measurement light flux is further adjusted,
Can measure more accurately.

[0006]

Therefore, according to the present invention, the intensity adjusting means can always obtain an appropriate scattered light flux intensity regardless of the surface color or surface condition of the object to be measured or the incident angle of the measurement light flux. It has become possible to provide a three-dimensional shape measuring device equipped with.

[0007]

EXAMPLES Examples will be described below. As shown in Figure 1,
The three-dimensional shape measuring device X-
Measuring beam bundle irradiating means A for irradiating the measuring object 2 placed on the Y reference plane 1, scattered beam bundle detecting means B for detecting scattered beam flux from the surface of the measuring object 2, and its And a signal processing means C for calculating and deriving the three-dimensional shape of the measuring object 2 based on the detection data by the scattered light flux detecting means B.

The measuring beam bundle irradiating means A comprises a light source 3 provided with a laser, a double-sided reflecting mirror 4 rotatable about an axis P along the Y-axis direction, and a first fixed mirror 5. The spot light flux from the light source 3 is scanned in the X-axis direction toward the measurement object 2 via the first fixed mirror 5 by the rotation of the double-sided reflection mirror 4.

The scattered light flux detection means B includes a second fixed mirror 6 for reflecting a part of the scattered light flux from the surface of the object 2 to be measured toward the back surface of the double-sided reflection mirror 4, and the double-sided reflection mirror 4. , A light receiving element 8 composed of a CCD image sensor, and an optical system 7 for condensing the scattered light beam bundle on the light receiving element 8, and a light beam which is scanned by the measuring light beam irradiating means A and scattered from the measuring object 2. Detect a bundle.

Further, the measuring beam bundle irradiating means A and the scattered beam bundle detecting means B are integrated to form an optical head H, and the optical head H is moved in the Y axis direction to perform scanning in the Y axis direction. A mechanism (not shown) is provided so that the measuring beam bundle can be scanned over the XY plane.

The signal processing means C is a control circuit using a microcomputer or the like, and has a position at which the light receiving element 8 detects the scattered light flux from the reference plane 1 and a position at which the current scattered light flux is detected. Deviation and the double-sided reflection mirror 4
The surface position of the measuring object 2 from the reference plane 1 is calculated and derived from the rotation angle and the like. That is, as shown in FIG. 2, the distance X ₀ X ₁ detected by the CCD image sensor is proportional to ΔX ₀ , and the surface position Z ₀ of the measuring object 2 from the reference plane 1 is Z ₀ × Since Z ₀ is obtained from the relationship of θ = ΔX ₀ , X of the measurement light flux is determined.
The XYZ coordinates of the surface of the measuring object 2 are derived from the irradiation position in the Y direction.

Based on the ratio of the intensity detected by the scattered ray bundle detecting means B to the intensity of the measured ray bundle at that time, the scattered ray bundle detecting means B adjusts the intensity of the measured ray bundle so that the detected intensity falls within a predetermined range. A strength adjusting means D for adjusting the strength is provided. More specifically, as shown in FIG. 3, the intensity adjusting means D inputs the intensity data I _n-1 detected by the light receiving element 8 and the output intensity F _n-1 of the light source 3 at that time, and outputs them between them. the ratio K _n derives as a control parameter for the current regulation for controlling the current supplied an operation circuit for deriving the output intensity F _n of the next light source 3 based on the following equation, to the light source 3 according to the value It is composed of a circuit and the like. Here _{K n = F n-1 /} I n-1 F n = K n · (I n-1 -I) + F n-1 = K n · I, K n is the control parameter, F _n-1 is the previous Laser output value, I _n−1 is the previous brightness value, F _n is the calculated value, and I is the corrected brightness value.

Generally, the average light quantity I _d detected by the light receiving element 8 is expressed by the following equation. I _d = (1 / π) · α · F _t · ρ · cos θ where α is a constant parameter of the light receiving optical system, F _t is the amount of light incident on the measurement object 2, ρ is a diffuse reflection coefficient, and θ is measurement. The angle between the direction of the normal to the surface of the object and the direction of the incident light (incident angle)
Is. From the above equation, for example, even when the light flux having the same incident light amount F _t is applied to the measurement object 2, the average light amount I _d is large if the incident angle θ is small and the incident angle θ is large. It will be smaller if there is. However, the control parameter K _n = F _n-1
/ I _n-1 (= F _t / I _d = π / α · ρ · cos θ) is
The smaller the incident angle θ is, the smaller the incident angle θ is, and the larger the incident angle θ is.
_{Even if n-1} −I is the same, the controlled variable K _n · (I _n-1 −
I) decreases relatively. The difference between the surface color and the state of the measuring object 2 is represented by the diffuse reflection coefficient ρ, and the change can be dealt with in the same manner as described above. Therefore, according to the surface state of the measurement location,
The brightness value detected by the light receiving element 8 can be kept within a certain range where accurate detection is possible.

Here, the intensity adjusting operation by the intensity adjusting means D is performed on the basis of the ratio of the intensity detected by the scattered ray bundle detecting means B in the vicinity of the measuring object portion to the measuring object 2 and the intensity of the measuring light flux at that time. By adjusting the intensity of the measurement light flux, it is possible to measure at extremely high speed. That is, FIG. 4 (a)
As shown in, on the assumption that the surface state in the vicinity of the measurement point does not change significantly, the spot light flux from the light source 3 is passed through the first fixed mirror 5 by the rotation of the double-sided reflection mirror 4. When scanning in the X-axis direction toward the measurement target 2 or in the Y-axis direction by the scanning mechanism, the adjustment amount of the output intensity of the light source 3 with respect to the next measurement point is a measurement value at a nearby position, for example, immediately before. It is decided based on the measured value.

Further, as shown in FIG. 4 (b), the intensity adjusting operation by the intensity adjusting means D is carried out by detecting the intensity detected by the scattered ray bundle detecting means B at the measurement target portion with respect to the measurement object 2 and the measurement light flux at that time. If the intensity of the measurement light beam is adjusted based on the ratio of the intensities, the measurement can be performed extremely accurately and reliably. That is, the adjustment amount of the output intensity of the light source 3 is determined based on the previous or multiple past measurement results at the same measurement point.

Another embodiment of the present invention will be described below. The configuration of the three-dimensional shape measuring apparatus that scans the spot light described in the above embodiments is not limited to this, and can be realized by various configurations such as driving and scanning the light source itself.

In the above embodiment, a laser oscillator is used as the light source,
Although the case where the CCD image sensor is used as the light receiving element has been described, the present invention is not limited to these and other elements can be used.

In the above embodiment, as the three-dimensional shape measuring device, the one in which the measuring object is scanned with the spot light is described. However, the measuring object is measured by using the light cutting method of scanning the measuring object with the slit light. It may be one that measures the cross-sectional shape.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Fig. 1] Overall configuration diagram of the three-dimensional shape measuring apparatus

FIG. 2 is an explanatory diagram showing the principle.

FIG. 3 is a block configuration diagram of a main part.

FIG. 4 is an explanatory diagram of strength adjusting operation.

[Explanation of symbols]

 2 object to be measured A measuring beam flux irradiating means B scattered beam flux detecting means C signal processing means D intensity adjusting means

Claims (3)

[Claims] 1. A measuring ray bundle irradiating means (A) for irradiating a measuring ray bundle in the form of a slit or a spot toward a measuring object (2), and a scattered ray bundle from the surface of the measuring object (2). And a signal processing means (C) for calculating and deriving the three-dimensional shape of the measuring object (2) based on the detection data by the scattered light flux detecting means (B). A three-dimensional shape measuring apparatus configured from the scattered light flux detecting means (B) based on the ratio of the intensity detected by the scattered light flux detecting means (B) to the intensity of the measured light flux at that time. So that the detection intensity is within the specified range,
A three-dimensional shape measuring apparatus comprising intensity adjusting means (D) for adjusting the intensity of the measurement light beam. 2. The intensity adjusting means (D) is a ratio between the intensity detected by the scattered light flux detecting means (B) in the vicinity of the measurement target position with respect to the measurement target (2) and the intensity of the measurement light flux at that time. The three-dimensional shape measuring apparatus according to claim 1, wherein the intensity of the measurement light beam is adjusted based on the above. 3. The intensity adjusting means (D) is based on the ratio of the intensity detected by the scattered light flux detecting means (B) at the measurement target position to the measurement target (2) and the intensity of the measurement light flux at that time. The three-dimensional shape measuring apparatus according to claim 1, wherein the intensity of the measurement light beam is adjusted.