JP3351374B2 - Laser distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser type distance measuring apparatus for measuring a distance to an object by scanning a laser beam emitted from a laser light source toward the object and capturing the reflected laser light. More specifically, the present invention relates to a laser type distance measuring device that scans at substantially the same time along three or more concentric scanning lines.

[0002]

2. Description of the Related Art As a laser scanning type distance measuring device, a two-dimensional raster scanning type is widely used.

In this conventional distance measuring device, a rotary polygon mirror for reflecting a laser beam emitted from a laser light source such as a laser diode, and the reflected light from the polygon mirror is reflected to an object while being reflected again. A rotating raster mirror that scans toward the target, and a sensor that captures the reflected laser light from the object as reflected light from the polygon mirror and the raster mirror and photoelectrically converts the reflected light, and rotates the two mirrors. The centers are 9
Because of the phase shift of 0 degree, the distance to the target is measured while the projected laser light is substantially scanned in the two-dimensional direction.

[0004]

The conventional laser type distance measuring apparatus as described above requires a rotation drive mechanism such as an independent motor for each mirror, so that the structure is complicated and the reduction in size and weight is limited. In addition, since the scanning method is a two-dimensional scanning method, the amount of data is large, and a high-performance computer is required for the processing, which increases the cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and achieves the intended purpose without depending on a high-performance computer while further reducing the size and weight of the entire apparatus. It is an object of the present invention to provide a laser distance measuring device that can be used.

[0006]

According to the first aspect of the present invention, a laser light source and a plurality of conical surfaces are respectively set at different angles, and the laser light emitted from the laser light source is supplied to each of the conical surfaces. A polygonal pyramid mirror that reflects the laser light from the surface and projects toward the object, and also captures the reflected laser light from the object on each conical surface, and the polygonal pyramid mirror is rotationally driven with its axis as the center of rotation. Mirror driving means for scanning the projection laser light reflected on each conical surface of the polygonal pyramid mirror in the rotational direction of the polygonal pyramid mirror, and disposed so as to face each conical surface of the polygonal pyramid mirror; It is characterized by comprising a condensing means for condensing the reflected laser light to be reflected, and a light receiving sensor for receiving the laser light condensed by the condensing means and photoelectrically converting the laser light.

The above-mentioned polygonal pyramid mirror is determined by the number of scanning lines to be scanned. For example, a triangular pyramid shape, a quadrangular pyramid shape, or a polygonal pyramid shape larger than that is used as necessary. .

According to a second aspect of the present invention, in the first aspect of the present invention, the condensing means comprises a parabolic converging mirror disposed so as to face each conical surface of the polygonal pyramid mirror; A turning mirror for reflecting the laser light condensed by the condensing mirror toward the light receiving surface of the light receiving sensor, wherein the focal point of the turning mirror matches the light receiving surface of the light receiving sensor. It is characterized by.

[0009] The invention described in claim 3 is the first invention.
Or a laser light passage hole formed in the polygonal pyramid mirror and passing the laser light from the laser light source only once per rotation of the polygonal pyramid mirror, A calibration optical fiber having a predetermined length for capturing the laser light passing through the laser light passage hole and guiding the laser light to the light receiving surface of the light receiving sensor is provided.

Therefore, according to the first aspect of the present invention,
The laser light emitted from the laser light source is reflected on each of the conical surfaces of a polygonal pyramid mirror that is rotationally driven, for example, a triangular pyramid mirror, and is projected toward an object. And, since the respective cone surfaces of the triangular pyramid mirror are set at different angles from each other, the reflected laser light from each cone surface is directed in a different direction, and as a result, the triangular pyramid mirror makes one rotation. The object is scanned along three concentric scanning lines.

On the other hand, the laser light reflected by the object is reflected by the corresponding conical surface of the triangular pyramid mirror, then condensed by the condensing means, and finally projected on the light receiving surface of the light receiving sensor and photoelectrically converted. Then, the distance to the object is measured for each scanning line as a function of the time required from when the laser light is first projected to when the light receiving sensor receives the reflected laser light.

According to the second aspect of the present invention, the focus of the parabolic converging mirror forming the condensing means does not directly coincide with the light receiving surface of the light receiving sensor. Since the laser light condensed by the method is once turned by the turning mirror and the focal point of the turning mirror is made to coincide with the light receiving surface of the light receiving sensor, the optical distance is shortened, which can contribute to the miniaturization of the entire apparatus.

According to the third aspect of the present invention, the laser light from the laser light source momentarily passes through the laser light passage hole of the polygonal pyramid mirror only once per rotation of the polygonal pyramid mirror, and the laser light passage hole passes through the laser light passage hole. The laser light that has passed through is caught by a calibration optical fiber having a predetermined length, and then guided to a light receiving sensor to be photoelectrically converted. Therefore, if the length of the optical fiber for calibration, which is the optical path, is known, the normal distance measurement data is corrected based on the distance measurement data when passing through the optical fiber, so that the temperature change in the distance measurement environment can be obtained. The distance measurement error based on, for example, is eliminated, and the measurement accuracy is improved.

[0014]

According to the first aspect of the present invention, the scanning is performed along three or more concentric scanning lines using a polygonal pyramid mirror as a main element. Only one axis is required to rotate the polygonal pyramid mirror, which makes it possible to reduce the size and weight of the entire device, and at the same time realizes a structure that is resistant to vibration and shock.
Since the processing data amount is significantly smaller than that of the conventional so-called two-dimensional raster scanning method, the minimum necessary distance data can be obtained without relying on a high-performance computer, which also simplifies the entire apparatus. There is an effect that can be achieved.

According to the second aspect of the present invention, the condensing means is constituted by a parabolic converging mirror and a return mirror, and the focal point of the converging mirror is directly matched with the light receiving sensor. Instead, the focal point of the return mirror receiving the reflected laser light from the condenser mirror is made to coincide with the light receiving sensor. Therefore, there is an advantage that the shortening of the optical distance can further contribute to downsizing of the entire apparatus.

According to the third aspect of the present invention, since the calibration optical fiber is provided, if the calibration processing of the distance measurement data is performed using the data at the time of passing through the optical fiber, the temperature change can be prevented. The distance measurement error due to the above-mentioned factors can be eliminated, and there is an effect that the distance measurement accuracy can be improved.

[0017]

1 and 2 show a preferred embodiment of a laser type distance measuring apparatus according to the present invention. FIG. 1 is a vertical sectional view, and FIG. 2 is a plan view. ing. Then, the laser type distance measuring apparatus 1 according to the present embodiment
Is used as a distance sensor for avoiding obstacles in an unmanned traveling vehicle system as shown in FIGS. 3A and 3B, for example. That is, the laser-type distance measuring apparatus 1 according to the present embodiment has a horizontal range of about 120 ° and a depression angle θ1, θ2, θ
3, scanning is performed along three concentric scanning lines S 1, S 2, and S 3 in front of the vehicle 2. The mounting height H of the distance measuring device 1 with respect to the vehicle 2 is set to, for example, about 1 to 2 meters, the distance from the vehicle 2 to the scanning line S1 is, for example, about 5 meters, and the distance to the scanning line S2. Is set to about 10 meters, and the distance to the scanning line S3 is set to about 20 meters.

As shown in FIGS. 1 and 2, this laser type distance measuring apparatus 1 has a transparent glass window 3 (angle G in FIG. 2).
Is formed as a mother body, and the case 4 is fixedly supported on the upper end of a column 5 erected on the vehicle 2 as an unmanned vehicle shown in FIG. A laser diode (semiconductor laser) with a collimator, which is a laser light source, is provided inside the bottom wall of the case 4.
6. In addition to a photodiode 7 as a light receiving sensor and an amplifier 8 for signal processing thereof, a fan-shaped condensing mirror having a parabolic mirror surface located above the laser diode 6 and the photodiode 7 9 are fixed, while a triangular pyramid mirror 10 and a flat motor 11 as a driving means thereof are arranged inside the upper wall portion of the case 4 so as to face the condensing mirror 9. .

At the position corresponding to the light projecting portion from the laser diode 6 and the position corresponding to the light receiving portion of the photodiode 7 in the condenser mirror 9, interference with the projected laser light and the received laser light is avoided, respectively. Through holes 12,
A laser beam L1 is projected from a laser diode 6 toward a triangular pyramid mirror 10 described later as parallel light, and a reflected laser beam L5 from a folding mirror 14 also described later is applied to the photodiode 7.
Is condensed.

Although the base of the triangular pyramid mirror 10 is formed in a flat cylindrical shape, three flat pyramids (mirror surfaces) at every 120 ° forming a truncated triangular pyramid shape.
10a, 10b and 10c are respectively set at different angles, and the three conical surfaces 10a, 10b and 10c are set at different angles.
At the top of the triangular pyramid formed by c, a folding mirror 14 which forms a condensing means together with the converging mirror 9 is fixed, and the triangular pyramid mirror 10 has its axis as a rotation center. The motor 11 is driven to rotate. And each conical surface 10a,
The angles of 10b and 10c are adjusted by the irradiation of the laser beam L1 from the laser diode 6 with respect to each of the conical surfaces 10a and 10c.
The reflected laser light L2 of b, 10c is depressed angle θ1, shown in FIG.
θ2 and θ3 are set.

That is, as shown in FIGS. 4 and 5, the conical surface for scanning the scanning line S1 shown in FIG. 3 is 10a, the conical surface for scanning the scanning line S2 is 10b, and the scanning line S3 Is assumed to be 10c, for example, the angle θa of the conical surface 10a is equal to the angle θa ′ formed between the perpendicular M and the vertical line N with respect to the conical surface 10a,
As a result, the angle θa ′ coincides with the angle θ1 shown in FIG. 3, and θa = θa ′ = θ1. The same applies to the angles θb and θc of the remaining conical surfaces 10b and 10c (provided that θa <θb <θc).

Therefore, as will be described later, if the triangular pyramid mirror 10 makes one rotation while the laser beam 6 is being emitted from the laser diode 6, it follows along the three scanning lines S1 to S3 shown in FIG. Scanning.

The folding mirror 14 is provided with a focusing mirror 9.
From the reflected light L4 from the photodiode 7
The focal point is made to coincide with the light receiving surface of the photodiode 7.

A single laser beam passage hole 15 is formed in a part of the triangular pyramid mirror 10, and a triangular prism 16 faces the back side of the laser beam passage hole 15. The laser light L1 emitted from the laser diode 6 during one rotation of the mirror 10 instantaneously passes through the laser light passage hole 15 to the back side of the triangular pyramid mirror 10. The triangular prism 16
Is connected to one end of an optical fiber 17 for calibration having a predetermined length, and the other end of the optical fiber 17 faces the light receiving surface side of the photodiode 7.

Therefore, the laser beam L1 emitted from the laser diode 6 while the triangular pyramid mirror 10 makes one rotation.
Is instantaneously captured only once by the triangular prism 16, and the laser light L 1 captured by the triangular prism 16 is guided to the photodiode 7 through the optical fiber 17. The distance measurement data when passing through the optical fiber 17 is managed by a data processing circuit (not shown), and by utilizing the fact that the length of the optical fiber 17 itself is known, the distance measurement data during normal distance measurement will be described later. Used as calibration data for distance data.

In the drawing, reference numeral 18 denotes a drive circuit for the motor 11, and 19 denotes a drive circuit for the laser diode 6.

Therefore, according to the laser distance measuring apparatus 1 configured as described above, when measuring the distance to the target object (not shown), the triangular pyramid mirror 10 is continuously rotated by the motor 11. Therefore, the irradiation laser light L1 emitted in parallel from the laser diode 6 is sequentially reflected with a predetermined time difference from each of the conical surfaces 10a to 10c of the triangular pyramid mirror 10 and is projected toward the target.

At this time, as described above, the triangular pyramid mirror 10
Since the angles of the respective conical surfaces 10a to 10c are different from each other, the respective conical surfaces 10a
The reflected laser beams L2 reflected by the scanning lines S1 to S10c are respectively concentric arc-shaped scanning lines S1 as shown in FIG.
Scanning is performed along 〜S3.

Then, the laser beam L2 irradiated toward the object is reflected again by the object, and is reflected again as a reflected laser beam L3 by the corresponding conical surface 10a of the triangular pyramid mirror 10.
10 to 10c. That is,
The laser beam L2 reflected on the conical surface 10a and applied to the object
Is reflected by the object and is also captured by the conical surface 10a. Similarly, the laser beam L2 reflected by the conical surfaces 10b and 10c and radiated to the object is reflected by the object, and then reflected by the object. Captured on surface 10b or 10c.
The laser light L3 captured by each of the conical surfaces 10a to 10c is sequentially reflected by the conical surfaces 10a to 10c, and is reflected and condensed by the condensing mirror 9 that is shared by the conical surfaces 10a to 10c. Further, the light is reflected by the turning mirror 14, is captured by the photodiode 7, and is converted into a predetermined electric signal. That is, the laser light L1
The distance to the target object is measured for each of the scanning lines S1, S2, and S3 as a function of the time required until the reflected laser light L4 is incident on the photodiode 7 after the light is irradiated, and a data processing circuit (not shown) Will be taken into.

Here, as described above, the triangular pyramid mirror 1
Since the distance measurement data when the laser beam L1 passes through the optical fiber 17 of a known length is obtained every one rotation of 0, the distance measurement data when passing the optical fiber 17 is used as calibration data. Using each scanning line S1
The distance measurement data for each S3 is corrected. This eliminates a measurement error due to, for example, a temperature change in the distance measurement space, and improves the distance measurement accuracy.

The laser beam L1 is emitted from the triangular pyramid mirror.
When hitting each of the conical surfaces 10a to 10c, and the conical surface 10
When the laser beam L2 reflected at a to 10c passes through the glass window portion 3, when a part of the laser beam L2 is scattered and directly enters the photodiode 7 to cause dazzling,
As shown in FIG. 1, a light shielding plate 20 is
And a light-shielding hood 21 is preferably provided around the light receiving portion of the photodiode 7.

[Brief description of the drawings]

FIG. 1 is a vertical sectional explanatory view showing a preferred embodiment of a laser type distance measuring apparatus according to the present invention.

FIG. 2 is an explanatory sectional view taken along the line aa of FIG. 1;

3A and 3B are schematic explanatory diagrams when the laser type distance measuring device is used as a distance sensor of an unmanned traveling vehicle system, where FIG. 3A is a side explanatory diagram and FIG. 3B is a plan explanatory diagram of FIG.

FIG. 4 is a bottom view of only the triangular pyramid mirror shown in FIG. 1;

FIG. 5 is an explanatory sectional view taken along line bb in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laser type distance measuring device 4 ... Case 6 ... Laser diode with collimator (laser light source) 7 ... Photodiode (light receiving sensor) 9 ... Condensing mirror (condensing means) 10 ... Triangular pyramid mirror (polygonal pyramid mirror) 11 ... Motor (mirror driving means) 14 fold-back mirror (condensing means) 15 laser beam passage hole 17 optical fiber L1, L2, L3, L4, L5 laser light

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01C 3/06 G01B 11/00 G01S 17/08

Claims (3)

(57) [Claims] 1. A laser light source, wherein a plurality of conical surfaces are respectively set at different angles, and a laser beam emitted from the laser light source is reflected by each conical surface and projected toward an object. A polygonal pyramid mirror that also captures the reflected laser light from the object on each of the conical surfaces; and a projection laser that reflects the polygonal pyramid mirror on each of the conical surfaces by rotating and driving the polygonal mirror around its axis. Mirror driving means for scanning light in the rotation direction of the polygonal pyramid mirror, and disposed so as to face each conical surface of the polygonal pyramid mirror;
A condensing means for condensing the reflected laser light reflected by the conical surface; and a light receiving sensor for receiving the laser light condensed by the condensing means and photoelectrically converting the laser light. Laser type distance measuring device. 2. The condensing means according to claim 1, wherein said condensing means has a parabolic converging mirror disposed so as to face each of the conical surfaces of the polygonal pyramid mirror, and receives a laser beam condensed by said converging mirror. 2. A laser distance measuring apparatus according to claim 1, further comprising: a reflecting mirror for reflecting light toward said light receiving surface, wherein a focal point of said reflecting mirror is matched with a light receiving surface of a light receiving sensor. apparatus. 3. A laser beam passing hole formed in the polygonal pyramid mirror and passing the laser beam from the laser light source only once per rotation of the polygonal pyramid mirror, and passing through the laser beam passing hole. The laser type distance measuring apparatus according to claim 1, further comprising a calibration optical fiber having a predetermined length for guiding the laser beam to the light receiving surface of the photoelectric sensor.