JPH0610615B2 - Multi-directional distance measuring device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device, and more particularly to a device for optically measuring a distance to an object in multiple directions. Such a device is used as a visual sensor for a self-propelled robot or an obstacle detection sensor for a vehicle collision prevention device.

[Conventional technology and its problems]

In self-propelled robots, the distance to surrounding objects is measured in multiple directions as a means for recognizing the surrounding environment, and it is possible to run while avoiding collisions with objects based on the distance information thus obtained. .

In a vehicle collision prevention device, distances to surrounding objects are measured in multiple directions as means for detecting obstacles, and other vehicles, walls, etc. are measured based on the distance information thus obtained. When an object is closer than a predetermined distance, a warning is issued to the driver or an instruction to stop or decelerate the vehicle is issued.

As a means for measuring the distance in multiple directions as described above, conventionally, a method has been used in which an ultrasonic wave is emitted to an object to be measured and an ultrasonic wave returning by reflection is analyzed to obtain a distance. There is.

However, this method has a problem in that it is difficult to perform measurement when the object to be measured is small, the resolution is relatively low, and it takes time to measure the distance to a distant object.

As a method of optically performing distance measurement in multiple directions, a slit-shaped light beam is projected onto an object to be measured, the bright line shape on the object surface is measured from a direction different from the projection direction, and the distance is calculated from the shape. Has been proposed.

However, this method has a problem that a relatively long time is required for inputting the bright line shape and the subsequent calculation.

Furthermore, there is a stereo method as an optical method.

However, the stereo method has a problem that it is difficult to improve the resolution in the measurement direction.

[Means for solving problems]

According to the present invention, in order to solve the above-mentioned problems of the prior art, a light source and a light beam from the light source are incident on a reflecting mirror having a reflecting surface on a surface intersecting with a reference plane, Scanning means for scanning while reflecting or projecting a reflected light beam from the reflecting surface on the object to be measured in the reference plane by rotating or rotating the reflecting mirror around a rotation axis,
Image forming means for forming an image on the reference plane by reflecting the reflected light beam from the object to be measured and measuring a change in the image forming position of the reflected light beam on the reference plane along the optical path direction. A multi-directional distance measuring device is provided, which is characterized in that it measures distance information to objects to be measured existing in multiple directions based on the measurement of the image-forming position measuring means. It

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

1 (a) and 1 (b) are schematic side views showing a first embodiment of the device of the present invention, and FIGS. 2 and 3 are schematic plan views thereof. In these drawings, reference numeral 1 denotes a light source, and as the light source, a light emitting part using a light emitting diode, a semiconductor laser, or the like can be used. The light source 1 has a built-in trimmer lens for collimating the luminous flux emitted from the light emitting portion. 2 is a convex lens, and 3 is a plane reflecting mirror. Reference numeral 4 is a rotating plane reflecting mirror, and only the plane reflecting surface is shown in FIGS. 1 (a) and 1 (b). Incidentally, FIG.
(a) and (b) show an expanded optical path reflected by the reflecting surface. As shown in FIGS. 2 and 3, the rotating plane reflecting mirror 4 has six plane reflecting surfaces. The reflector 4 is driven to rotate about an axis of rotation 4a, each reflecting surface being symmetrically located with respect to the axis of rotation 4a. In the figure, 5 is a convex lens, and 6 is a photoelectric conversion element. The photoelectric conversion element is a so-called position sensor whose output signal changes according to the position of incidence of the light spot, and is located on the extension of the optical path from the plane reflecting mirror 3 to the rotating plane reflecting mirror 4. The photoelectric conversion element 6 is protected by a sealing material 6a. The sealing material 6a has a chevron shape, and also serves to reduce the reflection of a light beam obliquely incident on its slope and efficiently guide it to the photoelectric conversion element 6. still,
In the above optical system, the focal position of the convex lens 2 and the focal position of the convex lens 5 coincide.

The parallel light flux emitted from the light source 1 is focused on the focal position of the convex lens 5 by the convex lens 2, is reflected by the plane reflecting mirror 3 and the rotating plane reflecting mirror 4, and then passes through the convex lens 5 to become a parallel light flux. This parallel light flux is reflected by the surface of the object to be measured, and a part of it passes through the convex lens 5 and is reflected by the rotating plane reflecting mirror 4 toward the object as shown in FIGS. 1 (a) and 1 (b). The projected light is incident on a position separated from the position on which the light is incident in the direction of the rotation axis, and is reflected to form an image. The imaging position at this time varies depending on the distance to the object to be measured. FIG. 1 (a) shows a case where an object to be measured (not shown) is at a relatively short distance. In this case, the photoelectric conversion element 6 is located at a position A relatively far from the reflecting mirror 4.
Image on top. FIG. 1 (b) shows the case where the object to be measured (not shown) is at a relatively long distance. In this case, an image is formed on the photoelectric conversion element 6 at a position B relatively close to the reflecting mirror 4. To do.

Therefore, if the relationship between the image formation position on the photoelectric conversion element 6 and the distance to the object to be measured is obtained in advance, the distance to the object to be measured can be immediately obtained from the output of the photoelectric conversion element 6.

The above relationship is maintained substantially the same even when the reflecting mirror 4 is rotated around the rotation axis 4a. That is, as shown in FIG. 2, the light beam emitted from the light source 1 is projected in the direction indicated by the solid line after being reflected by the reflecting mirror 4 when the reflecting mirror 4 is in the rotation position shown by the solid line, and is reflected. When the mirror 4 is in the rotational position shown by the dotted line, it is projected in the direction shown by the dotted line after being reflected by the reflecting mirror. In addition, the light beam projected on the object to be measured and reflected by the object in this way has a convex lens 5 as shown by the solid line when the reflecting mirror 4 is at the rotation position shown by the solid line, as shown in FIG.
And an image is formed on the photoelectric conversion element 6 via the reflection mirror 4, and when the reflection mirror 4 is in the rotation position shown by the dotted line, it is formed on the photoelectric conversion element 6 via the convex lens 5 and the reflection mirror 4 as shown by the dotted line. The image is formed. Thus, a part of the reflected light beam from the object to be measured is imaged on the photoelectric conversion element 6 regardless of the direction of the light beam projection by the rotary reflecting mirror 4.
Therefore, by rotating the reflecting mirror 4, it is possible to measure the distance to the object to be measured within a predetermined angle range. Incidentally, when the reflecting mirror 4 is rotated, the reflecting mirror itself is rotated by a certain angle within the time until the reflected light from the object to be measured reaches the anti-slope of the reflecting mirror. Shifts in a direction perpendicular to the plane of the paper in FIG. 1. However, when the angular velocity of the rotation of the reflecting mirror is constant, this shift amount can be calculated in advance, and the photoelectric conversion element 6 can be appropriately moved or further the flat reflecting mirror can be moved. It is possible to perform correction by forming an image on the photoelectric conversion element 6 by intervening and appropriately rotating.

According to the present embodiment, by continuing the rotation of the reflecting mirror 4, it is possible to successively and continuously measure the distance to the object to be measured within a predetermined angle range using the adjacent reflecting surfaces. .

4 (a) and 4 (b) are schematic side views showing a second embodiment of the device of the present invention, and FIG. 5 is a schematic plan view thereof. In these drawings, the same members as those in FIGS. 1 to 3 are designated by the same reference numerals, and the description thereof will be omitted here.

In the figure, numeral 7 is a convex cylindrical lens, and its cylindrical axis direction is a direction perpendicular to the paper surface in FIG. Further, 8 is a convex cylindrical lens, and its cylindrical axis direction is a direction perpendicular to the paper surface in FIG. 9
Is a convex lens, and 10 is a photoelectric conversion element. The photoelectric conversion element 10 is a position sensor similar to the photoelectric conversion element 6. The convex lens 9 and the photoelectric conversion element 10 are
It exists directly below the optical path from the light source 1 through the convex cylindrical lens 7 to the rotary reflecting mirror 4. In this optical system, the focal line position of the convex cylindrical lens 7 and the focal line position of the convex cylindrical lens 8 coincide.

The parallel light flux emitted from the light source 1 is moved by the convex cylindrical lens 7 to the fourth position on the focal line position of the convex cylindrical lens 8.
The lens is focused only in the direction along the plane of the drawing, is reflected by the rotary plane reflecting mirror 4, and then enters the convex cylindrical lens 8, and is focused by the lens only in the direction along the plane of the paper in FIG. It becomes a luminous flux.

In the present embodiment, the convex cylindrical lens 7 is used.
A horizontal plane (a plane perpendicular to the paper surface in FIG. 4) S including the optical axis of 1 and the optical axis of the convex cylindrical lens 8 is hereinafter referred to as a reference plane.

Thus, the parallel light flux emitted from the convex cylindrical lens 8 is reflected on the surface of the object to be measured, and a part of it passes through the convex cylindrical lens 8 and is subjected to the focusing action, so that it is shown in FIGS. As shown in FIG. 5, an image is formed after being incident on the rotating plane reflecting mirror 4 at a position separated from the position where the projection light is incident on the object in the rotation axis direction. The imaging position at this time varies depending on the distance to the object to be measured. FIG. 4A shows the case where the object to be measured (not shown) is at a relatively short distance. In this case, the image is formed at a position C relatively distant from the reflecting surface of the reflecting mirror 4. FIG. 4 (b) shows the case where the object to be measured (not shown) is at a relatively long distance, and in this case, the position D relatively close to the reflecting surface of the reflecting mirror 4.
Image on. These image forming positions C and D are both on the reference plane S. Incidentally, these images are formed only in the vertical direction. Therefore, the image becomes a long line in the horizontal direction.

The convex lens 9 has a predetermined portion of the reference plane S (that is,
An image is formed on the photoelectric conversion element 10 at a portion (Q) including the image forming positions C and D, which covers all positions within the range where the reflected light beam from the measured object within the distance range to be measured forms an image. . That is, the photoelectric conversion element 10 is arranged at a position conjugate with the predetermined portion Q of the reference plane S with respect to the convex lens 9, and further, the convex cylindrical lens 8 from the object to be measured.
The light flux that has passed through the lens and is incident on the reflecting surface of the reflecting mirror 4 and reflected to form an image in the predetermined portion Q is incident on the photoelectric conversion element 10 through the convex lens 9.

Therefore, the image forming position on the reference plane S can be known from the output of the photoelectric conversion element 10, and the position of the measured object can be known from the image forming position. Thus, if the relationship between the imaging position on the photoelectric conversion element 10 and the distance to the object to be measured is obtained in advance, the distance to the object to be measured can be immediately obtained as the output of the photoelectric conversion element 10.

It is the same as in the case of the first embodiment described above that the above relationship is maintained substantially at the same time even when the reflecting mirror 4 is rotated around the rotation axis 4a. However, in this embodiment, since the image on the reference plane S is long in the horizontal direction as described above, the reflecting mirror 4
Even if the image position shifts in the horizontal direction due to the rotation of, the detection of the image formation position by the photoelectric conversion element 10 is not substantially affected.

In the second embodiment, the image formed in the predetermined portion Q in the reference plane S is further formed on the photoelectric conversion element 10 by using the convex lens 9, but in the present invention, the above-mentioned predetermined image is formed. A photoelectric conversion element may be arranged in the portion Q to measure the image formation position.

FIG. 6 is a schematic side view showing a third embodiment of the device of the present invention. In this figure, the same members as those in FIG. 4 are designated by the same reference numerals, and a description thereof will be omitted here.

This embodiment is a modification of the second embodiment. In this embodiment, the convex cylindrical lens 11 has the reference plane S.
It does not have a neighboring part, and there is no convex cylindrical lens between the light source 1 and the rotating plane reflecting mirror 4. The parallel light flux emitted from the light source 1 is reflected by the rotating plane reflecting mirror 4 and immediately thereafter projected onto the object to be measured. Others are the same as those in the second embodiment.

According to this embodiment, the number of constituent parts can be reduced.

In the above embodiment, the reflecting mirror is a rotating polygon mirror,
In the present invention, the reflecting mirror may have only one surface. In the case of a reflecting mirror consisting of only one surface, it is possible to continuously rotate in the same direction and continuously perform multidirectional distance measurement as in the above-mentioned embodiment, or to provide a predetermined angle range around the rotation axis. It is also possible to rotate the inside to continuously perform multidirectional distance measurement.

Further, in the device of the present invention, in order to distinguish the external light and the light flux from the light source to increase the S / N ratio and improve the measurement accuracy, an infrared light emitting element is used as a light source and visible light is emitted in front of the photoelectric conversion element for light reception It is also possible to apply a method such as placing a cutoff filter or modulating the light source to emit light and taking out the output of the photoelectric conversion element in synchronization with the modulation.

Further, in the present invention, a plane reflecting mirror is arranged on the optical path projected from the condenser lens to the object to be measured, and the plane reflecting mirror is arranged around a rotation axis that is non-parallel to the rotation axis of the rotating plane reflecting mirror. It is also possible to perform a two-dimensional light beam scanning by rotating it and perform distance measurement in three-dimensional directions.

〔The invention's effect〕

According to the present invention as described above, the distance measurement results in multiple directions can be immediately obtained as a time-series electrical signal, and since complicated arithmetic processing is not required, high-speed measurement can be performed with a relatively simple configuration. be able to.

Further, according to the present invention, since the measurement result can be obtained by measuring the position of the image formed optically, the resolution can be easily improved by increasing the accuracy of the optical system.

[Brief description of drawings]

1 (a) and 1 (b) are schematic side views for explaining the device of the present invention, and FIGS. 2 and 3 are schematic plan views thereof. 4 (a) and 4 (b) are schematic side views for explaining the device of the present invention. Further, FIG. 5 is a schematic plan view thereof. FIG. 6 is a schematic side view for explaining the device of the present invention. 1: light source, 2, 5, 9: convex lens, 3: flat reflecting mirror,
4: rotating flat reflecting mirror, 4a: rotating shaft, 6, 10: photoelectric conversion element, 7, 8, 11: convex cylindrical lens.

Claims (3)

[Claims] 1. A light source and a light beam from the light source are incident on a reflecting mirror having a reflecting surface on a surface intersecting with a reference plane,
Scanning means for scanning while reflecting or projecting the reflected light beam from the reflecting surface on the object to be measured in the reference plane by rotating or rotating the reflecting mirror around a rotation axis, and a reflected light beam from the object to be measured. An image forming means for forming an image on the reference plane by reflecting the light on the reflecting mirror and an image forming position measuring means for measuring a change in the image forming position along the optical path direction of the reflected light flux on the reference plane. A multi-directional distance measuring device, characterized in that it measures distance information to an object to be measured that exists in multiple directions based on the measurement of the imaging position measuring means. 2. The scope of claim 1, wherein the reflecting mirror has a plurality of reflecting surfaces symmetrically arranged with respect to one rotation axis.
Multi-direction distance measuring device of paragraph. 3. The image forming position measuring means detects the change of the re-image forming position by the optical means for re-forming the light beam emitted from the image forming position to the outside of the reference plane. The multidirectional distance measuring device according to claim 1, further comprising a detection element that measures a change in an image forming position on the reference plane.