JPS6287809A - Method for measuring multidirectional distance - Google Patents

Abstract

PURPOSE:To enable the measurement of the distance up to a multidirectional matter, by allowing luminous flux to be incident on a rotary flat reflective mirror and scanning matter to be measured while the reflected luminous flux thereof is projected to said matter to be measured and reflecting the reflected luminous flux from the matter to be measured by the flat reflective mirror to form an image. CONSTITUTION:The parallel luminous flux emitted from a light source 1 is converged to the focal position of a convex lens 5 by a convex lens 2 are reflected by a flat reflective mirror 3 and a rotary flat reflective mirror 4 and the reflected luminous flux passes through the lens 5 to be converted to parallel luminous flux which is, in turn, incident on matter to be measured to be reflected therefrom. A part of the reflected luminous flux from said matter passes through the lens 5 and reflected by the mirror 4 to form an image on a photoelectric converter element 6. The image forming positions A, B are determined by the distance up to the matter. Therefore, if the relation between the image forming position on the element 6 and the distance up to the matter is preliminarily calculated, the distance up to the matter can be immediately detected from the output of the element 6. The mirror 4 has six flat reflective surfaces and, by succeedingly rotating the mirror 4 around a rotary shaft, the distance up to the matter present in a predetermined angular range can be repeatedly and continuously measured at a high speed successively using adjacent reflective surfaces.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring method, and more particularly to a method for optically measuring distances to objects in multiple directions. Such a method is used as a visual sensor for a self-propelled robot and an obstacle detection sensor for a collision prevention device of an automobile.

[Conventional technology and its problems]

In self-propelled locomotives, the distance to surrounding objects is measured in multiple directions as a means of recognizing the surrounding environment, and based on the distance information obtained in this way, the vehicle moves while avoiding collisions with objects. be able to.

In addition, in collision prevention systems for automobiles, distances to surrounding objects are measured in multiple directions as a means of detecting obstacles, and based on the distance information obtained in this way, it is possible to detect obstacles such as other cars or walls. When the vehicle approaches an object by a predetermined distance, a warning is issued to the driver or an instruction to stop or decelerate the vehicle is issued.

The conventional method for measuring distances in multiple directions as described above is to emit ultrasonic waves at the object to be measured and analyze the reflected ultrasonic waves to determine the distance. It is used.

However, this method has problems in that it is difficult to measure 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 for optically measuring distances in multiple directions, a slit-shaped light beam is projected onto the object to be measured, the shape of the bright line on the object surface is measured from a direction different from the direction of projection, and the distance is calculated from the shape. A method has been proposed to find the .

However, this method has a problem in that it takes a relatively long time to input the emission line shape and perform subsequent calculations.

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

However, the stereo method has a problem in 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 problems of the prior art as described above, a light beam from a light source is made incident on a plane reflecting mirror, and the plane reflecting mirror is rotated about a rotation axis in a direction parallel to the reflecting surface. The reflector is rotated or pivoted to scan the object to be measured while projecting the reflected light beam from the reflecting mirror onto the object to be measured, and the reflected light beam from the object to be measured is reflected by the plane reflecting mirror and passed through the condenser lens. A multidirectional distance measuring method is provided, which comprises forming an image and measuring the position of the image.

〔Example〕

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

1(!L) and (b) are schematic side views showing a first embodiment of the method 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 a light source using a light emitting diode, a semiconductor radar, or the like as a light emitting part can be used as the light source. The light source 1
has a built-in collimator lens for collimating the luminous flux of the light emitting section.

2 is a convex lens, and 3 is a flat reflecting mirror. Reference numeral 4 denotes a rotating plane reflecting mirror, and only its plane reflecting surface is shown in FIGS. 1(a) and 1(b). Furthermore, Figure 1 (
(a) and (b) are expanded views of the 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 reflecting mirror 4 is driven to rotate around a rotation axis 4a, and each reflecting surface is positioned symmetrically with respect to the rotation axis 4a. In the figure, 5 is a convex lens, and 6 is a photoelectric conversion element. The photoelectric conversion element is a so-called I-position sensor whose output signal changes depending on the incident position of the light spot, and is located on an extension of the optical path from the flat reflecting mirror 3 to the rotating flat reflecting mirror 4. The photoelectric conversion element 6 is made of a material 6
It has been retained by &. The sealing material 6a has a chevron shape, and also has the function of reducing reflection of the light beam incident obliquely on its slope and efficiently guiding it to the photoelectric conversion element 6. In the above optical system, the focal position of the convex lens 2 and the focal position of the convex lens 5 coincide.

A parallel beam of light emitted from a light source 1 is focused by a convex lens 2 to the focal point of a convex lens 5, reflected by a plane reflecting mirror 3 and a rotating plane reflecting mirror 4, and then passes through the convex lens 5 to become a parallel beam.

This parallel light beam 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 9-turn flat reflector 4 to form an image. The imaging position at this time differs depending on the distance to the object to be measured.

FIG. 1(,) shows a case where the object to be measured (not shown) is located relatively close to each other. Form an image. FIG. 1(b) shows a case where the object to be measured (not shown) is located at a relatively long distance. Image.

Therefore, if the relationship between the imaging position on the photoelectric conversion element 6 and the distance to the object to be measured is determined 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 almost the same even if the reflecting mirror 4 is rotated around the rotation axis 4a. BIJ, as shown in FIG. 2, when the reflecting mirror 4 is in the rotational position shown by the solid line, the light beam emitted from the light source 1 is projected in the direction shown by the solid line after being reflected by the reflecting mirror, When the reflecting mirror 4 is in the rotational position shown by the dotted line, the light is reflected by the reflecting mirror and then projected in the direction shown by the dotted line. Furthermore, as shown in FIG. 3, when the reflecting mirror 4 is in the rotational position shown by the solid line, the light beam projected onto the object to be measured and reflected by the object passes through the convex lens as shown by the solid line. When the reflecting mirror 4 is in the rotational position shown by the dotted line, the image is formed on the photoelectric conversion element 6 via the convex lens 5 and the reflecting mirror 4 as shown by the dotted line. image is formed. Thus, one rotation reflection! 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 4.

Therefore, by rotating one reflecting mirror 4, the distance to the object to be measured within a predetermined angular range can be measured. Note that when the reflecting mirror 4 is rotated, the internal pressure reflecting mirror itself is rotated by a certain angle during the time it takes for the reflected light from the object to be measured to reach the reflecting surface of the reflecting mirror, so strictly speaking, the imaging position is The deviation occurs in the direction perpendicular to the plane of the paper in FIG. By appropriately rotating the intervening pattern, it is possible to correct the image formation on the photoelectric conversion element 6.

According to this embodiment, by continuing to rotate the reflecting mirror 4, it is possible to repeatedly and continuously measure the distance to the object to be measured within a predetermined angular range by sequentially using adjacent reflecting surfaces at high speed. can.

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

In the figure, 7 is a convex cylindrical lens, the cylindrical axis direction of which is perpendicular to the plane of the paper in FIG.

8 is a convex cylindrical lens, and its cylindrical axis direction is perpendicular to the plane of the paper in FIG. 9 is a convex lens, and 1° is a photoelectric conversion element. The photoelectric conversion element 10 is a position sensor similar to the photoelectric conversion element 6 described above. The convex lens 9 and the photoelectric conversion element 10 are connected to the rotating reflecting mirror 4 from the light source 1 through the convex cylindrical lens 7.
It is located directly below the optical path leading to . In this optical system, the focal line position of the convex cylindrical lens 7 and the focal a position of the convex cylindrical lens 8o coincide.

The parallel light beam emitted from the light source 1 is transmitted to the fourth focal line position of the convex cylindrical lens 8 by the convex cylindrical lens 7.
It is focused only in the direction along the plane of the paper in the figure, and after being reflected by the rotating plane reflector 4, it enters the convex cylindrical lens 8, and the lens receives a focusing action only in the direction along the plane of the paper in Figure 4. is a parallel beam of light.

In this embodiment, the convex cylindrical lens 7
A horizontal plane S (a plane perpendicular to the plane of the paper in FIG. 4) that includes the optical axis of the convex cylindrical lens 8 and the optical axis of the convex cylindrical lens 8 will hereinafter be referred to as a reference plane.

In this way, the parallel light beam exiting 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 focused and formed into an image. The imaging position at this time differs depending on the distance to the object to be measured. Figure 4 (&) is the object to be measured (not shown)
In this case, the image is formed at a position C that is relatively far from the reflecting surface of the reflecting mirror 4.

FIG. 4(b) shows a case where the object to be measured (not shown) is located at a relatively long distance, and in this case, the image is formed at a position relatively close to the reflecting surface of the reflecting mirror 4. These imaging positions C,
Both D are on the reference plane S. Note that these images are formed only in the vertical direction.

Therefore, the image becomes a long linear image in the horizontal direction.

The convex lens 9 is located at a predetermined portion of the reference plane S (i.e.,
A portion Q that includes the image formation positions C and D and covers all positions within the image formation range of the reflected light beam from the object to be measured within the distance range to be measured is imaged on the photoelectric conversion element 10. . That is, the photoelectric conversion element 10 is disposed at a position conjugate with a predetermined portion Q of the reference plane S with respect to the convex lens 9, and furthermore, the photoelectric conversion element 10 is located at a position conjugate with the predetermined portion Q of the reference plane S, and furthermore, the convex cylindrical lens 8
The light beam passes through the convex lens 9, enters the reflecting surface of the reflecting mirror 4, is reflected, and forms an image within the predetermined portion Q, and then enters the photoelectric conversion element 10 through the convex lens 9.

Therefore, the image formation position on the reference plane S can be determined from the output of the photoelectric conversion element 10, and the position of the object to be measured can be determined from the image formation 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 determined in advance, the distance to the object to be measured can be immediately obtained as the output of the photoelectric conversion element 10.

As in the case of the first embodiment, the relationship described above is maintained substantially the same even when the reflecting mirror 4 is rotated about the rotation axis 4m. 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, it does not substantially affect the detection of the image position by the photoelectric conversion element 10.

In the second embodiment, the image formed within the predetermined portion Q within the reference plane S is further formed onto the photoelectric conversion element 10 using the convex lens 9, but in the present invention, the image formed within the predetermined portion Q within the reference plane The imaging position may be measured by placing a photoelectric conversion element in the portion Q of .

FIG. 6 is a schematic side view showing a third embodiment of the method of the present invention. In this figure, the same members as in FIG. 4 are given the same reference numerals, and their explanations will be omitted here.

This embodiment is a modification of the second embodiment.

In this embodiment, the convex cylindrical lens 11 does not have a portion near the reference element surface S, and there is no convex cylindrical lens between the light source 1 and the rotating plane reflecting mirror 4. The parallel light beam emitted from the light source 1 is reflected by the rotating plane reflector 4 and immediately projected onto the object to be measured. The rest is the same as the second embodiment.

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

In the above embodiment, the reflecting mirror consists of a rotating polygon mirror,
In the present invention, the reflecting mirror may consist of only one surface. In the case of a reflecting mirror consisting of only one surface, it is possible to continuously measure distances in multiple directions by continuing to rotate in the same direction as in the above embodiment, or by rotating the rotation axis at a predetermined angle. It is also possible to continuously measure distances in multiple directions by rotating within the range.

In addition, in the method of the present invention, in order to increase the S/N ratio and improve measurement accuracy by distinguishing between external light and the luminous flux from the light source, an infrared light emitting element is used as a light source, and visible light is emitted in front of the photoelectric conversion element for receiving light. It is also possible to apply a method such as placing a cutoff filter or modulating a light source to emit light and outputting an output from a photoelectric conversion element in synchronization with the modulation.

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

〔Effect of the invention〕

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

Furthermore, according to the present invention, measurement results can be obtained by measuring the position of an optically formed image, so the resolution can be easily improved by increasing the accuracy of the optical system. .

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are schematic side views for explaining the method of the present invention, and FIGS. 2 and 3 are schematic plan views thereof. FIGS. 4(a) and 4(b) are schematic side views for explaining the method of the present invention. Moreover, FIG. 5 is a schematic plan view thereof. FIG. 6 is a schematic side view for explaining the method of the present invention. 1: Light source, 2, 5, 9: Convex lens, 3: Thousand-sided reflector, 4
: Rotating plane reflecting mirror, 4a: Rotation axis, 6°10: Photoelectric conversion element, 7, 8, 11: Convex cylindrical lens. Agent Patent Attorney Minoru Yamashita Children Figure 1 (G) Figure 1 (b) Figure 3 Figure 4 (0) Figure 4 (b) Figure 5 Figure 6

Claims (2)

[Claims] (1) The light flux from the light source is made incident on a plane reflecting mirror, and the plane reflecting mirror is rotated or rotated around a rotation axis in a direction parallel to the reflecting surface, and the reflected light flux from the reflecting mirror is thus measured. A multifunction device characterized in that the object is scanned while being projected onto the object, the reflected light beam from the object to be measured is reflected by the plane reflecting mirror and passed through a condensing lens to form an image, and the image forming position is measured. Directional distance measurement method. (2) The multidirectional distance measuring method according to claim 1, wherein the plane reflecting mirror has a plurality of reflecting surfaces arranged symmetrically about one rotation axis.