JPH0566116A - Three-dimensional position measuring device - Google Patents

Abstract

PURPOSE:To provide a highly precise three-dimensional position measuring device with a wide dynamic range. CONSTITUTION:A light emitting part A consisting of a laser light source 100 for emitting a He-Ne laser beam L as a probe light and a rotatable reflecting mirror 103 for reflecting the He-Ne laser beam L to a subject 102, a light detecting part B consisting of a rotatable reflecting mirror 105 for guiding the reflected light RL of the laser beam L by the subject 102 to a CCD image sensor 104 which is a light emitting element, and a received light integrating circuit 106 for regulating the light receiving quantity of the CCD image sensor 103 are provided. The integrating time of the scattered light received by the CCD image sensor 104 is regulated according to the intensity of the light to improve light receiving sensitivity and dynamic range, so that a three- dimensional measurement can be performed continuously from a short distance to a long distance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional measuring device capable of measuring a three-dimensional shape of a subject with high accuracy.

[0002]

2. Description of the Related Art For example, a technique for measuring strain of a building, a stockpiling tank or the like with high accuracy is important from the viewpoint of maintenance of these. Here, strain is understood as a change in the three-dimensional shape of a symmetrical object over time, but in maintenance inspection, a resolution of several mm is required as the measurement accuracy, so high-precision three-dimensional shape measurement technology is required. To be done. An example of this three-dimensional shape measuring technique will be described below.

The three-dimensional position measuring apparatus shown in FIG. 4 was previously filed by the applicant of the present application (Japanese Patent Laid-Open No. 2-30060).
No. 9).

As shown in the figure, in the light irradiation section A, the light emitted from the He-Ne laser light source 1 passes through a variable attenuator 2 and a beam expander 5 composed of lenses 3 and 4. Are reflected by the mirror 6 and the emitted light forms an image on the surface a of the subject 7. Here, the variable attenuator 2 is for preventing the received light level of the observation system from changing due to the influence of the inclination and the reflectance of the surface of the subject 7. Further, the expander 5 is for reducing the spread angle of the He—Ne laser light, and by moving the lens mounting stage 8 on which the lens 4 is mounted, the beam diameter on the surface a is minimized. Has been adjusted. On the other hand, the mirror 6 is mounted on the rotary stage 9,
It is driven by the motor 10, and its rotational position is read by the rotary encoder 11 as a rotation angle θ which is the inclination of the reflected light from the optical axis.

On the other hand, in the photodetector B for detecting the reflected light from the subject 7, the image pickup optical system 12 is composed of the image pickup lens 13 and the detector 14, and the lens mount stage 15 on which the lens 13 is mounted is moved. The spot system in the detector 13 is adjusted so as to be the minimum, and the imaging lens 13, the detector 14, and the lens mounting stage 15 are mounted on the rotary stage 16 so that the motor 1
The rotary angle ψ is read by the rotary encoder 18.

Further, the above-mentioned light irradiation section A and light detection section B
Is held on a pedestal 19 and is driven by a motor 20, the center of rotation of which is coincident with the optical axis of the He—Ne laser light, and the rotation angle ω is the rotary encoder 21.
Read by. The mirror 6 and the light receiver 14
Are parallel to each other and intersect the optical axis of the He-Ne laser light at right angles at points b and c, respectively.

The variable attenuator 2, the lens mounting stage 8 and the motor 10 in the light irradiation section A, the lens mounting stage 15, the motor 17 and the motor 20 in the light detecting section B are the driver 22 and the controller 23.
Controlled by the rotary encoder 1
The data of 1, 18 and 21 are read by the reading counter 24. The CPU 25 calculates the position of the surface a of the subject 7 based on the series of controls and data.

In this apparatus, by controlling the beam expander 5 and the rotary stage 9, an image adjusted so that the beam diameter is minimized is formed on the surface a to be measured of the subject 7, and this image is The rotation stage 16 is controlled so as to be centered on the optical axis of the image pickup optical system 12, and the lens mounting stage 15 is moved so that the spot diameter in the detector 14 is adjusted to be the minimum. By using the rotation angles θ, ψ and the distance x _m between the points b and c at this time, the position of the surface a of the subject 7 can be calculated by the principle of triangulation. Further, the rotation angles θ and ω are changed and the measurement is sequentially performed in the same manner, so that the three-dimensional mapping of the reflection point position of the subject 7 can be performed.

[0009]

By the way, in the above-described three-dimensional position measuring device shown in FIG. 4, when measuring the three-dimensional position of a short distance and a long distance, for example, a three-dimensional position 1 m directly above the measuring device is measured. When measuring and height of 25m ahead 6
There is a problem that a difference in received light amount of about 660 times occurs when the three-dimensional position of m is measured. Also, when the reflectance of the object was measured in the range of the incident angle of 0 ° (directly above) necessary for measurement to the incident angle of 88 ° (height 1 m at 25 m ahead), it was 1/7 for oblique incidence as compared to front incidence. There is a problem that the reflectance becomes small. Further, the reflectance may be extremely low depending on the subject, and since the scattered light is weak, it is necessary to enhance the light receiving sensitivity and expand the dynamic range.

In view of the above circumstances, it is an object of the present invention to provide a three-dimensional position measuring device capable of measuring a three-dimensional position with high accuracy and a wide dynamic range.

[0011]

The structure of the three-dimensional position measuring apparatus according to the present invention for achieving the above object is to irradiate a subject with parallel light or convergent light as probe light, and to rotate the light in two irradiation directions. A light irradiator that is variable by rotation about an axis, an imaging lens and a light receiving element, and the optical axis direction is variable by rotation about two rotation axes, and the reflected light from the subject is reflected. Of the photodetection section for rotationally adjusting so that the image of the point coincides with the optical axis and for detection, the emitting direction of the probe light and the light receiving direction at the photodetection section, and the photodetection section and the light irradiation section. A three-dimensional position measuring device comprising a processing unit for detecting the position of the reflection point on the principle of triangulation from the relative positional relationship, wherein the light receiving element is an integral type sensor and the light receiving element detects Receives light based on the intensity of scattered reflected light Characterized in that it has a control means for controlling the integration time of the child.

[0012]

In the above structure, the intensity of the scattered reflected light received by the light receiving element is detected, and the light receiving integration time in the light receiving element is controlled based on the intensity to obtain an appropriate sensitivity, thereby controlling the sensor sensitivity. To do.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a three-dimensional position measuring apparatus according to this embodiment. FIG. 2 shows a light receiving integration circuit diagram.

As shown in these drawings, inside the frame 100, a laser light source 101 that emits He—Ne laser light L as a probe light, and this He—Ne laser light L is reflected to the subject 102. The CCD image sensor 10 which is a light receiving element for the light irradiation section A composed of the rotatable reflecting mirror 103 and the reflected light RL of the laser light L at the subject 102.
4 and a photodetection section B consisting of a rotatable reflecting mirror 105
And a light reception integration circuit 106 for adjusting the amount of light received by the CCD image sensor 104. Further, the θ axis that is the rotation axis of the light irradiation unit A and the ψ axis that is the rotation axis of the light detection unit B are the straight lines that connect the rotation center of the light irradiation unit A and the rotation center of the light detection unit. It is provided so as to be orthogonal to.
Therefore, in the figure, the ω-axis, the θ-axis, and the ψ-axis have a relationship of ω⊥θ and ω⊥ψ, and also a relationship of θ // ψ.
Incidentally, 107 and 108 are lenses for adjusting laser light.

In the above structure, the He-Ne laser light L emitted from the laser light source 101 is reflected by the reflecting mirror 103 and emitted to the subject 102. Next, the reflected light RL from the subject 102 is guided to the CCD image sensor 104, which is a light receiving element, by rotating the reflecting mirror 105.

At this time, the rotation angles θ, ψ of the rotation axes θ, ψ
Using the distance x _m between the reflecting mirrors 103 and 105, the position of the surface a of the subject 102 can be calculated according to the principle of triangulation. Further, three-dimensional mapping of the reflection point position of the object 102 can be performed by changing the rotation angles θ and ω and sequentially performing similar measurements.

Since the detector is rotationally controlled so that the reflected light coincides with the center of the optical axis, a one-dimensional line sensor or a detector with a pinhole is preferable, and a two-dimensional detector may be used.

Now, changing the integration time according to the intensity will be described with reference to FIG. 2 which is a light receiving integration circuit diagram for adjusting the amount of light received by the CCD image sensor 104 which is a light receiving element. An integration time control circuit 11 that detects the reflected light of the subject received by the CCD image sensor 104 by the light intensity detection circuit 110 and controls the integration time according to the light intensity.
1 is activated and the accumulation time is, for example, 0.5 m / sec to 512
Adjust to the range of m / sec (1024 times),
Increase the photosensitivity and dynamic range. Therefore, it is possible to continuously measure the three-dimensional position from a short distance to a long distance.

Here, the light intensity generally increases / decreases in accordance with the integration time, and as shown in FIG. 3, the saturated exposure amount (indicated by F in the figure) is 15 to 9 of the (light amount at which the accumulated charges are saturated).
The exposure amount is preferably 0% (indicated by A in the figure).
The dynamic range in this case is 6: 1 (90:15)
Since it corresponds to the
0/6 = It is necessary to expand the dynamic range by about 770 times (4600: 1 (≈) when considering the 660 times difference in received light amount and the decrease in reflectance (1/7) in the conventional case.
A dynamic range of 660 × 7: 1) is required. ).

[0021]

As described above with reference to the embodiments, the three-dimensional position measuring apparatus according to the present invention adjusts the integration time of the reflected light received by the light receiving element according to the intensity of the light, thereby obtaining the light receiving sensitivity and the dynamic. It is possible to solve the shortage of the range, and it is possible to measure three-dimensional position continuously from near objects to far objects.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a three-dimensional position measuring apparatus according to this embodiment.

FIG. 2 is a light receiving integration circuit diagram thereof.

FIG. 3 is a diagram showing a relationship between a light reception saturation amount and time.

FIG. 4 is a schematic diagram of a conventional three-dimensional position measuring apparatus.

[Explanation of symbols]

 100 frame 101 laser light source 102 subject 103 reflecting mirror 104 CCD image sensor 105 reflecting mirror 106 light receiving integration circuit 107 lens 108 lens 110 light intensity detection circuit 111 integration time control circuit L laser light RL reflected light

Claims (1)

[Claims] 1. A light irradiation unit that irradiates a subject with parallel light or convergent light as probe light, and the irradiation direction of the light is variable by rotating about two rotation axes, an imaging lens and a light receiving element. An optical detection unit which has an optical axis direction which is variable by rotation about two rotation axes and which adjusts rotation of the reflected light from the subject so that an image of the reflection point coincides with the optical axis; A processing unit that detects the position of the reflection point on the principle of triangulation based on the emitting direction of the probe light, the light receiving direction at the light detection unit, and the relative positional relationship between the light detection unit and the light irradiation unit. A three-dimensional position measuring device provided, wherein the light receiving element is an integral type sensor, and has a control means for controlling the integration time of the light receiving element based on the intensity of scattered reflected light detected by the light receiving element. 3D position measuring device characterized by ..