JPH08261752A - Triangulation type distance measuring device and obstacle detection device - Google Patents

Abstract

PURPOSE: To make possible measuring a distance to a measuring object with mirror surface of which direction is unknown. CONSTITUTION: Light is cast from a roughly point light source 35 to a plane mirror 40 and its reflection light is received with a light reception part 33 on standard side and a light reception part 34 on reference side by way of a first and a second optical systems 31 and 32. Brightness signals from both reception parts 33 and 34 are input in a computer, parallax is calculated by the comparison of two brightness signals, and the distance Dk to a virtual image 35' of the point source 35 with the triangulation principle is calculated. Furthermore, from the distance Dk and the distance Doff from the point light source 35 to the optical system and equation h=(Dk-Doff)/2, the distance to the plane mirror 40 is calculated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a triangulation type distance measuring device capable of measuring a distance even on a mirror-reflected measuring object and an obstacle detecting device using the triangulation type distance measuring device.

[0002]

2. Description of the Related Art As a conventional distance measuring device, it has two sets of optical systems and a light receiving part, and light from a measurement object is received by each corresponding light receiving part through each optical system, and the intensity of the received light beam. A lightness signal corresponding to the distribution is output from each light receiving unit, and the output mutual lightness signals are compared, for example, while shifting the other lightness signal with one lightness signal as a reference, and the correlation is calculated. Passive triangulation type distance measuring device for obtaining a position shift amount when the brightness signal most approximated to one reference brightness signal is obtained and calculating a distance from this shift amount when the brightness signal is highest. (For example, JP-A-50
-138825 gazette).

The principle of a conventional passive triangulation type distance measuring device will be described with reference to FIGS. 23 and 24. However, the object to be measured shall be in front of the distance measuring device. The light from the measuring object 1 passes through the first optical system 2 and is received by the reference side light receiving section 3, and the reference side light receiving section 3 obtains a first brightness signal 4 according to the intensity distribution of the received light beam. . Also, measurement target 1
The light from is received by the reference side light receiving section 6 through the second optical system 5, and the reference side light receiving section 6 obtains the second brightness signal 7 of the received light beam.

In this case, the position 1'of the object to be measured 1, the lens center position 2'of the second optical system 2, the lens center position 5'of the second optical system 5, and the optical axis of the second optical system 5 are used. The positional relationship between the intersection 8 of the reference-side light-receiving unit 6, the position 9 on the reference-side light-receiving unit 6 where the light from the measurement target 1 focuses and the optical axis 10 of the first optical system 2 is as shown in FIG. . At this time, triangle 1'-2 '
-5 'and triangle 5'-8-9 are similar.

Here, the distance (measurement distance) between the position 1'of the object 1 to be measured and the lens center position 2'of the first optical system 2 is measured.
Is Dj, the distance (baseline length) between the lens center position 2'of the first optical system 2 and the lens center position 5'of the second optical system 5 is B, and the focal lengths of the optical systems 2 and 5 are f. Assuming that the distance (parallax) between the intersection 8 with the optical axis on the reference side light receiving unit 6 and the position 9 where the light from the measurement target 1 focuses is Dj / B = f / R ( 1) holds. From the equation (1), Dj = B · f / R (2), and the distance Dj from the optical system to the measurement target 1 is
It can be calculated from the equation (2).

Therefore, since the base line length B and the focal length f can be measured in advance, if the parallax R is known, the distance Dj
Can be calculated. As described above, the parallax R is
Since the lightness signals 4 and 7 obtained from the reference side light receiving unit 3 and the reference side light receiving unit 6 are compared and calculated as the shift amount when the mutual correlation is highest, the lightness signal 4 from each light receiving unit 3 and 6 is calculated. ，
By detecting 7, the distance Dj to the measurement target can be calculated.

[0007]

However, in the conventional triangulation type distance measuring device of this type, when the measurement target is a mirror surface, the virtual image reflected on the measurement target surface is not the distance to the measurement target. There was a problem that the distance to could be measured. As a conventional distance measuring device when the measurement target is a mirror surface, the light from one substantially point light source is detected by a plurality of light receivers, and the positional relationship between the substantially point light source and the received light receivers and the angle of the plane mirror are detected. To the object to be measured, or the light rays from a plurality of approximate point light sources are detected by one light receiver, and the positions of the approximate point light source and the light receiver turned on when the light receiver receives the light A method for calculating the relationship and the distance from the angle of the plane mirror to the object to be measured (Japanese Patent Laid-Open No. 51-40169).
(See Japanese Laid-Open Patent Publication No. 2004-242242), light from one approximate point light source is imaged on the position detecting element using the light receiving lens, the position of the light on the position detecting element, the positional relationship between the approximate point light source and the light receiving lens, A device for calculating the distance from the angle to the measurement target
The former principle of distance measurement (see Japanese Patent Publication No. 255905) is described with reference to FIGS. 25 and 26.

The light projected from the narrow directional light source 11 is reflected by the plane mirror 12 and is incident on the light receiver 13. Narrow directional light source
It is assumed that 11 and each light receiving body 13 are lined up on the reference line, and the reference line and the plane mirror 12 are parallel to each other. If the angle of the plane mirror 12 with respect to the reference line does not change, the distance Dm to the plane mirror 12 can be calculated by Dm = J / 2 tan θ (3) J is a distance between the narrow directional light source 11 and the light receiving body 13, and θ is an angle formed by the narrow directional light source 11 with respect to an axis orthogonal to the plane mirror 12.

When the light from one light source is detected by a plurality of light receivers as shown in FIG. 25, when the plane mirror 12 moves from the position a to the position b, the light receiver 13 which receives the light is different.
When light from a plurality of light sources is detected by one light receiver as shown in FIG. 26, the light source 11 that emits the light received by the light receiver 13 differs depending on the position of the plane mirror 12. Therefore, in any case, depending on the position of the plane mirror 12, the distance J between the light source 11 and the light receiver 13
Changes, the flat mirror 12 can be detected by detecting this distance J.
The distance Dm to can be calculated.

Next, the latter principle of distance measurement will be described with reference to FIG. The position of the substantially point light source is L, the center position of the light receiving lens is O, the position of the plane mirror is T, a perpendicular is drawn from the substantially point light source to the plane mirror, the intersection is Q, and the light from the substantially point light source is reflected at a point P on the plane mirror. Then, when the position on the light receiving body which is focused by the light receiving lens is X and the intersection point on the extension line of the straight line LQ and the straight line OP is I, L, O are calculated according to the principle of triangulation explained in FIG. , X, and the angle of the plane mirror, the distance from the position L to the point light source I can be calculated. Since the triangles L-Q-P and I-Q-P are equal, the distance from the point light source to the plane mirror is half the distance from L to I.

However, in the above-mentioned conventional apparatus for measuring the distance of a measurement object whose surface is a mirror surface, the distance to the plane mirror cannot be measured unless the angular relationship between the measurement object flat mirror and the distance measuring apparatus is known. There is a problem that it cannot be used when the measurement target is unspecified. The present invention has been made in view of such conventional problems. Focusing on the reflection of a virtual image of a light source on a mirror surface, the principle of triangulation is used to measure the distance of an unspecified measuring object. An object of the present invention is to provide a triangulation type distance measuring device that is capable of measuring distance even with a measurement object that is specularly reflective. Further, an obstacle detection device using this triangulation type distance measuring device is provided.

[0012]

Therefore, in the triangulation type distance measuring device of the first invention, as shown in FIG. 1, the light source B for irradiating the measuring object A with light and the light from the measuring object A are used. And first and second optical systems C and D for respectively receiving light, and a reference side light receiving means E for outputting a first lightness signal indicating an intensity distribution state of light received via the first optical system C. , Comparing the first lightness signal and the second lightness signal with the reference side light receiving means F that outputs the second lightness signal indicating the intensity distribution state of the light received via the second optical system D. Measuring means G for measuring the amount of deviation of the light receiving position of the reference side light receiving means from the light receiving position of the surface of the reference side light receiving means, and the virtual image of the light source using the principle of triangulation based on the amount of deviation measured by the measuring means G. To the first distance calculation means H for calculating the distance to When the distance to the virtual image is Dk and the distance from the light source to the optical system is Doff, the distance Dh to the measurement object is calculated by the following equation: Dh = (Dk-Doff) / 2 I and.

Further, in the triangulation type distance measuring device according to the second invention, as shown in FIG.
And second light sources B and B ', first and second optical systems C and D into which light from the measurement object A enters, and intensity distributions of light received through the first optical system C. A reference side light receiving means E for outputting a first lightness signal indicating the state, and a reference side light receiving means F for outputting a second lightness signal indicating the intensity distribution state of the light received via the second optical system D. , The first lightness signal and the second lightness signal are compared for each irradiation light of each of the light sources B and B ', and the deviation amount of the light receiving position of the reference side light receiving means with respect to the light receiving position of the surface of the reference side light receiving means is calculated for each light source Measuring unit G for measuring each irradiation light, and calculating the distance to each virtual image of each light source using the principle of triangulation based on each deviation amount of each light source with respect to the irradiation light measured by the measuring unit G. The distance between the first distance calculation means H and each virtual image calculated by the first distance calculation means H is Dk. ₁ , Dk ₂ , and the respective distances from the first and second light sources to the optical system are Doff ₁ , Doff ₂
Then, the distance Dh to the measurement target is Dh = (Dk ₂ · Doff ₁ −Dk ₁ · Doff ₂ ) /
The second distance calculating means I which is calculated by the arithmetic expression (Dk ₁ −Doff ₂ −Dk ₂ + Doff ₁ ) is provided.

Further, the triangulation type distance measuring device of the first and second inventions is provided with a judging means for judging whether or not the object to be measured is a mirror surface based on the brightness signal of at least one of the light receiving means. , When it is determined that the measurement target is not a mirror surface,
The value calculated by the first distance calculating means based on the displacement amount obtained when the light source is turned off is set as the distance to the measurement target, and when it is determined that the measurement target is a mirror surface, the second The value calculated by the distance calculation means may be used as the distance to the measurement target.

The determination means determines whether or not there is a peak value higher than a preset threshold value in the brightness signal, and when there is a peak value higher than the threshold value, it is determined that the measurement target is a mirror surface and the peak value higher than the threshold value. When the object does not exist, it is determined that the measurement target is not a mirror surface. Further, the determination means calculates the difference between the value of the lightness signal when the light source is turned on and when the light source is turned off,
It is determined whether the calculated difference signal has a peak value higher than a preset threshold value, and when the difference signal has a peak value higher than the threshold value, the measurement target is determined to be a mirror surface, and a peak value higher than the threshold value exists. It may be configured to determine that the measurement target is not a mirror surface when not performing.

The determination means calculates the spatial differential value of the brightness signal or the difference signal, determines whether or not there is a peak value higher than a preset threshold value in the absolute value of the calculated spatial differential value, and determines from the threshold value. The measurement target may be determined to be a mirror surface when a high peak value exists, and the measurement target may not be a mirror surface when a peak value higher than the threshold value does not exist. Further, the measuring means compares the difference signal between the values of the first lightness signal when the light source is turned on and off and the difference signal of the second lightness signal when the light source is turned on and off to compare the light receiving position. It is advisable to adopt a configuration for measuring the amount of deviation.

The distance between the intersection of the optical axis of the first optical system and the light receiving position on the surface of the reference side light receiving means is Rd, the focal length of the first optical system is f, and the direction of the object to be measured. It is preferable that the angle θh be provided with a direction angle calculating unit that calculates the angle θh by the arithmetic expression of θh = atan (f / Rd).

It is preferable to use a cylindrical lens for both optical systems. Further, an optical filter that cuts light other than the wavelength of the irradiation light of the light source may be installed between the measurement target and the light receiving means. In the obstacle detection device of the present invention, as shown by the dotted lines in FIGS. 1 and 2, display means is provided, and the position information of the measuring object obtained by the above-mentioned triangulation type distance measuring device is input to the display means. This is a configuration for displaying the position of the measurement target.

Further, it is preferable that the display means has a fan-shaped display portion and displays the position of the measuring object with the position of the fan as the position of the distance measuring device.

[0020]

According to the structure of the first aspect of the present invention, when the object to be measured is a mirror surface, the distance to the virtual image of the light source reflected on the object to be measured is triangulated by the first distance calculating means. The object to be measured is a mirror surface and is unspecified by calculating from the principle and calculating the distance from the calculated distance to the virtual image and the distance between the light source and the optical system from the second distance calculating means using a predetermined calculation formula. Even in the case, it is possible to calculate the distance to the measurement target.

Further, as in the second aspect of the present invention, by providing two light sources, the distance can be measured even if the object to be measured is a curved mirror. Further, as described in claim 3, by providing a function of determining whether the measurement target is a mirror surface or a non-mirror surface, it is possible to perform distance measurement according to the surface state of the measurement target. Further, as described in claim 8, if the deviation amount of the light receiving position is measured from the signal of the difference in the value of the brightness signal when the light source is turned on and off, the influence of external light other than the light source is reduced. Therefore, the S / N is improved, and the distance measurement accuracy is enhanced.

Further, if a cylindrical lens is used in the optical system, the detection range is expanded in the vertical direction, and distance measurement is possible even if the measurement target is tilted in the vertical direction. Further, by providing an optical filter that cuts light other than the wavelength of the light emitted from the light source, the influence of external light can be reduced and the S / N can be improved. The obstacle detecting device according to claim 12 can easily grasp the position of the obstacle by the display means, and is suitable for an obstacle detecting system mounted on an automobile or the like.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 shows the configuration of an embodiment of a distance measuring device in which the plane mirror of the first invention is the object of measurement. In the figure, the case
A first optical system 31 and a second optical system 32 are arranged on the front surface of 30 with a space. Behind the first optical system 31, the first
A reference side light receiving section 33 which is a reference side light receiving means for receiving the light entering through the optical system 31 is disposed, and the reference side light receiving section 33 is disposed behind the second optical system 32 via the second optical system 32. A reference side light receiving section 34 which is a reference side light receiving means for receiving the shining light is arranged.
The reference side light receiving unit 33 and the reference side light receiving unit 34 are configured to output a first lightness signal and a second lightness signal corresponding to the intensity distribution state of the received light, respectively. First optical system 31
In the space inside the case 30 between the second optical system 32 and the second optical system 32, a substantially point light source 35 using an LED or the like for irradiating the measurement object with light is arranged.

The computer 36 outputs a control signal for turning on / off to the LED driver 37 for driving the substantially point light source 35, and the reference side light receiving section 33 and the reference side light receiving section 34 based on the irradiation light of the substantially point light source 35. Each lightness signal is converted into a digital value via the A / D converter 38 and taken in, and written in the storage device 39 via the data bus. First and second written
Based on the lightness signal information of the reference light receiving unit 34, the second lightness signal on the reference light receiving unit 34 side is sequentially shifted and compared with the first lightness signal of the reference light receiving unit 33, and when the correlation is highest (first When the second brightness signal is most similar to the brightness signal of
The shift amount is calculated as the shift amount (parallax). Furthermore, when the measurement target is a plane mirror using the principle of triangulation based on the calculated displacement amount, the distance to the virtual image of the approximate point light source 35 reflected on the plane mirror is calculated, and the calculated value and the approximate value are calculated. The distance between the point light source 35 and the optical system and the distance to the measurement target are calculated.

Therefore, the computer 36 has the functions of measuring means for measuring the amount of deviation, first distance calculating means and second distance calculating means. Next, with reference to FIGS. 4 and 5, the principle of distance measurement of the apparatus of this embodiment will be described. First, a case where the measurement target is a plane mirror and the plane mirror is parallel to the optical system will be described with reference to FIG.

The light from the substantially point light source 35 is reflected by the plane mirror 40 to be measured and passes through the first optical system 31 to receive the light on the reference side.
The light enters the reference side light receiving unit 34 through the second optical system 32. Therefore, from the formula (2), which is the distance calculation formula based on the distance measuring principle of the conventional passive triangulation type distance measuring device, from the formula (2), Dk = B · f / R (4) The distance Dk to 35 'can be calculated. However, B is the distance (baseline length) between the lens center positions 31 'and 32' of the optical systems 31 and 32, f is the focal length of the optical system, and R is the reference side light receiving section 33 and the reference side light receiving section 34. It is a shift amount (parallax) obtained from the comparison result of the brightness signals.

If the distance (offset) between the first and second optical systems 31 and 32 and the substantially point light source 35 is Doff, the distance Dh from the optical system to the plane mirror 40 is Dh = (Dk-Doff ) / 2 (5), and the distance to the plane mirror 40 can be calculated from the equation (5) when the optical system and the plane mirror are parallel to each other.

Next, a case where the object to be measured is a plane mirror and the plane mirror is not parallel to the optical system will be described with reference to FIG. Virtual image position 35 'of the point light source 35, lens center position 31' of the first optical system 31, lens center position of the second optical system 32
32 ', a straight line 3 from the lens center position 32' of the second optical system 32
The positional relationship between the intersection 8 of the line extending parallel to 5'-31 'and the reference side light receiving portion 34 and the position 9 on the reference side light receiving portion 34 where the reflected light of the light from the substantially point light source 35 focuses is shown in FIG. It becomes like 5.
At this time, the triangle 35'-31'-32 'and the triangle 32'-8-
9 is similar, and equation (4) holds. However, the distance D
k is the shortest distance from the reference line connecting 31'-32 'of each optical system to the virtual image 35', B is the above-mentioned baseline length, f is the focal length of the optical system, and R is the parallax. Therefore, the shortest distance Dh from the reference line connecting the lens center positions 31'-32 'of the optical system to the plane mirror 40 can be calculated by the equation (5), which is a distance calculation formula when the plane mirror is parallel to the optical system.

The direction angle θh of the plane mirror 40 with respect to the reference line can be calculated by θh = atan (f / Rd) (6) However, Rd is the light receiving section 33 on the reference side.
It is the distance from the point of intersection with the optical axis of the first optical system 31 above to the imaging position. The measurement distance D obtained by the equation (5)
h is the shortest distance, and the accurate distance Dr from the lens center position 31 'of the first optical system 31 to the plane mirror 40 can be corrected by: Dr = Dh / sin θh (7)

FIG. 6 shows a flow chart of the distance measuring operation of the apparatus of this embodiment. In step 1 (indicated by S1 in the drawing, the same applies hereinafter), a light source lighting command is generated to the LED driver 37 to light the substantially point light source 35. In step 2, each lightness signal from the reference side light receiving section 33 and the reference side light receiving section 34 is read as a digital signal through the A / D converter 38 and stored in the storage device 39.

In step 3, the shift amount i of the reference side light receiving section 34 is set to zero. In step 4, the reference side light receiving part
The brightness signal of 34 is sequentially shifted, and the correlation is calculated by comparing with the brightness signal of the reference side light receiving unit 33 at each shift amount. In step 5, it is determined whether the shift amount i has reached the predetermined amount n, and the correlation calculation of step 4 is executed until the shift amount i reaches the predetermined amount n. When the predetermined amount n is reached, the process proceeds to step 6.

In step 6, the shift amount when the correlation is highest is calculated as the parallax R based on the calculation result of step 4. In step 7, the parallax R calculated in step 6 and the distance (baseline length) B between the lens center positions of the known optical system.
And the focal length f, the distance Dk to the virtual image is calculated by the equation (4) using the principle of triangulation.

In step 8, the distance Dk calculated in step 7 and the distance Dof between the known optical system and the point light source are known.
The distance Dh to the measurement target is calculated from f by the equation (5). As described above, according to the present embodiment, since the distance and the direction to the plane mirror can be calculated regardless of the direction angle of the plane mirror 40, the direction angle of the measurement target, which was not possible with the conventional distance measuring device for the mirror surface. Distance can be measured even for unspecified objects with unknown.

Next, an embodiment of the second invention in which the measuring object is a curved mirror will be described. FIG. 7 shows the configuration of the embodiment apparatus. The same elements as those of the first embodiment shown in FIG. 3 are designated by the same reference numerals. In FIG. 7, a first optical system 31 and a second optical system 32 are arranged on the front surface of a case 30 with a space therebetween, and a reference side, which is a reference side light receiving means, is provided behind the first optical system 31. The light receiving section 33 is arranged, and the reference side light receiving section 34 which is the reference side light receiving means is arranged behind the second optical system 32.
The reference side light receiving section 33 and the reference side light receiving section 34 respectively output a first lightness signal and a second lightness signal corresponding to the intensity distribution state of the received light. In the apparatus of this embodiment, the first
In the space inside the case 30 between the optical system 31 and the second optical system 32, in addition to the point light source 35 which is a first light source using an LED or the like for irradiating the measurement object with light, , And second
This is different from the first invention in that a point light source 41, which is a light source, is arranged.

The computer 36 has two substantially point light sources 35 and 41.
A control signal for turning on / off the light is output to the LED driver 37 for driving the light source, and each brightness signal based on the light from the point light sources 35 and 41 from the reference side light receiving section 33 and the reference side light receiving section 34 is converted into an A / D converter.
It is converted into a digital value via 38 and taken in, and is written in the storage device 39 via the data bus. Each memorized point light source
Based on the first and second brightness signal information for each of 35 and 41, for example, the second brightness signal on the reference side light receiving section 34 side is sequentially shifted and compared with the first brightness signal on the reference side light receiving section 33. Then, the shift amount when the correlation is highest is calculated for each of the substantially point light sources 35 and 41 as the shift amount (parallax). Based on these calculated deviations, the distance to each virtual image of the point light sources 35 and 41 reflected on the curved mirror is calculated using the principle of triangulation, and the calculated values and the point light sources 35 and 41 and the optical system are calculated. The distance to each curved mirror, which is the object of measurement, is calculated from each distance between the two.

Therefore, the computer 36 has the functions of measuring means for measuring the amount of deviation, first distance calculating means and second distance calculating means. Next, with reference to FIGS. 8 and 9, the principle of distance measurement of the apparatus of this embodiment will be described. FIG.
Shows the case where the light from one approximate point light source 35 is applied to the curved mirror 42, and FIG. 9 shows the case where the light from the other approximate point light source 41 is applied to the curved mirror.

In this case, the distance (offset) from the approximate point light source 35 to the reference line connecting the optical systems 31 and 32 is Doff ₁ , the distance between the approximate point light source 41 and the reference line is Doff ₂ , and the approximate point light source 35 Virtual image 35 'and the center position of each lens of the optical systems 31 and 32 3
'The shortest distance between the reference line connecting the Dk _1, virtual image 41 of a substantially point source 41'1'-32 the minimum distance reference line connecting the center of the lens position 31 '-32' and Dk _2. The distance to be measured from the reference line to the curved mirror 42 that is the measurement target is Dh.
Let Dk ₁ -Dh be Dr ₁ and Dk ₂ -Dh be Dr ₂ .
Distances Dr ₁ , D to the virtual images 35 ', 41' reflected on the curved mirror 42
When r ₂ is approximated by the distance from the curved mirror 42 to the real image (actual approximate point light source) using the coefficient α that changes depending on the curvature of the curved mirror 42, the following equation holds.

Dr ₁ = α · (Dh + Doff ₁ ) (8) Dk ₁ = Dh + Dr ₁ (9) Dr ₂ = α · (Dh + Doff ₂ ) (10) Dk ₂ = Dh + Dr ₂ ... (11) (8), (9) from the _{equation, Dk 1 = α · (Dh} + Doff 1) + Dh ··· (12) (10), (11) from _{equation, Dk 2 = α · (Dh} + Doff 2) + Dh ・ ・ ・ (13) α ・ (Dh + Doff ₂ ) = Dk ₂ −Dh ・ ・ ・ (14) α = (Dk ₂ −Dh) / (Dh + Doff ₂ ) ・ ・ ・ (15) (12) are substituted into equation, Dk ₁ = _{[(Dk 2 -Dh) / (Dh} + Doff 2) ] _{· (Dh + Doff 1) +} Dh ··· (16) (Dk 1 -Dh) · (Dh + Doff 2) = (Dk _{2 -Dh) · (Dh + Do} ff 1) ··· (17) -Dh · Dh + (Dk 1 -Dof _{2) · Dh + Dk 1 ·} Doff 2 = -Dh · Dh + (Dk 2 -Doff 1) · Dh + Dk 2 · Doff 1 ··· (18) (Dk 1 -Doff 2 -Dk 2 + Doff 1) · Dh = Dk 2 · Doff ₁ −Dk ₁ · Doff ₂ (19) Dh = (Dk ₂ · Doff ₁ −Dk ₁ · Doff ₂ ) / (Dk ₁ −Doff ₂ −Dk ₂ + Doff ₁ ) ··· (20) Where , Doff ₁ and Doff ₂ are known and D
k ₁ and Dk ₂ are calculated from the equation (4) according to the principle of triangulation if the parallax is calculated from the lightness signals from the reference side light receiving section 33 and the reference side light receiving section 34 for each of the substantially point light sources 35 and 41. Therefore, the shortest distance Dh from the curved mirror 42 to the reference line connecting the lens center positions 31'-32 'of the optical system can be obtained from the equation (20).

FIG. 10 shows a flowchart of the distance measuring operation of the apparatus of this embodiment. In step 11, the LED driver 37 is instructed to turn on the first point light source 35 to turn on the point light source 35. In step 12, each lightness signal from the reference side light receiving section 33 and the reference side light receiving section 34 is read as a digital signal via the A / D converter 38 and stored in the storage device 39.

In step 13, the shift amount i of the reference side light receiving section 34 is set to zero. In step 14, the reference side light receiving unit
The brightness signals of 34 are sequentially shifted, and the correlation is calculated by comparing with the brightness signal of the reference side light receiving unit at each shift amount. In step 15, it is determined whether or not the shift amount i has reached the predetermined amount n, and the correlation calculation in step 14 is executed until the shift amount i reaches the predetermined amount n. When the predetermined amount n is reached, the process proceeds to step 16.

In step 16, after a command to turn off the first approximate point light source 35 is generated, a command to turn on the second approximate point light source 41 is generated to turn on the approximate point light source 41. Correlation calculation is executed in steps 17 to 20 in the same manner as steps 12 to 15 in the case of the first approximate point light source 35. In step 21, based on the calculation results of steps 14 and 19, the shift amount when the correlation is highest is calculated as the parallax R ₁ and R ₂ of each of the first and second substantially point light sources 35 and 41.

In step 22, from the parallaxes R ₁ and R ₂ calculated in step 21, the distance (baseline length) B between the lens center positions of the known optical system, and the focal length f, the principle of triangulation is used (4 ), The distance Dk to each virtual image 35 ', 41'
₁ and Dk ₂ are calculated. In step 23, from the distances Dk ₁ and Dk ₂ calculated in step 22 and the distances Doff ₁ and Doff ₂ between the known optical system and the point light source, the distance Dh to the measurement target is calculated from the equation (20). calculate.

As described above, according to this embodiment, the distance to the curved mirror can be calculated regardless of the angle of the curved surface. next,
Another embodiment will be described. In this embodiment, the influence of external light other than the point light source is removed. The hardware configuration is the same as that of the above-described embodiment, only the software configuration is different, and its operation will be described below with reference to the flowchart of FIG.

In step 31, a command for lighting the substantially point light source is generated to light the substantially point light source. In step 32, the brightness signals of the reference side light receiving portion and the reference side light receiving portion when the point light source is turned on are read. In this case, the standard-side brightness signal 61a and the reference-side brightness signal 62a having the intensity distribution as shown in FIG. 12A are obtained. In step 33, a command to turn off the approximate point light source is generated to turn off the approximate point light source.

In step 34, the lightness signals of the reference side light receiving portion and the reference side light receiving portion when the point light source is turned off are read. In this case, the standard side brightness signal 61b and the reference side brightness signal 62b having the intensity distribution as shown in FIG. 12B are obtained. Step 35
Then, based on the lightness signal information stored in steps 32 and 34, the difference between the lightness signals when the point light sources of the standard side light receiving unit and the reference side light receiving unit are turned on and off is calculated. FIG.
The difference signal 61c on the standard side and the difference signal 62c on the reference side are shown in (C).

In step 36, the shift amount i of the reference side light receiving section 34 is set to zero. In step 37, the difference signal 62c of the reference side light receiving portion 34 calculated in step 35 is sequentially shifted,
At each shift amount, the correlation is calculated by comparing with the difference signal 61c of the reference side light receiving unit. In step 38, it is judged whether or not the shift amount i has become the predetermined amount n, and when the shift amount i has become the predetermined amount n and the correlation calculation of all the difference signals is completed, the routine proceeds to step 39.

In step 39, the shift amount when the correlation is highest is calculated as the parallax R based on the calculation result of step 37, and then the distance Dh to the measurement object is calculated in the same manner as described above. As described above, the approximate point light source is blinked in accordance with the timing of the brightness signal generation, and the difference between the brightness signal when the approximate point light source is turned on and when it is turned off is calculated on the reference side and the reference side, respectively. If the distance Dh is calculated using the difference signals 61c and 62c, the influence of external light other than the point light source is reduced, the S / N is improved, and the distance measurement accuracy can be improved.

Next, another embodiment will be described. In this embodiment, it is possible to determine whether the measurement target is a mirror surface or a non-mirror surface. Also in this case, the hardware configuration is the same as that of the above-described embodiment, only the software configuration is different, and its operation will be described below with reference to the flowcharts of FIGS. 13 and 14.

When the object to be measured is a mirror surface, a virtual image of a substantially point light source reflected on the mirror surface is detected. Therefore, as shown in FIG. 15 (A), the brightness signal or difference signal 71 from each light receiving section 33, 34 is detected.
Has a clear peak, but when the measurement target is not a mirror surface, as shown in FIG.
There is no clear peak at 71. Therefore, the computer 36 is provided with a function of a determination unit that determines whether or not the measurement target is a mirror surface based on the presence or absence of the peak of the brightness signal or the difference signal 71. When the distance Dh calculated by the method of the present invention and the distance measurement result of the distance Dj by the conventional triangulation match, either distance measurement result may be used. When the distance measurement results do not match, which distance measurement result is selected is determined according to the determination result of whether it is a mirror surface.

In the flowcharts of FIGS. 13 and 14,
Steps 41 to 46 are the same as the flowchart in FIG. 11, and when the point light source is turned on and off,
The lightness signal and the difference signal in the light receiving sections on the reference side and the reference side are read, and the shift amount i is set to zero. In step 47, the correlation between the reference side brightness signal and the reference side brightness signal when the point light source is turned off is calculated, and when it is determined in step 48 that all the correlation calculations have been completed, the process proceeds to step 49, and The distance Dj is calculated according to the principle of triangulation.

In step 50, the shift amount i is set to 0. In step 51, the correlation calculation is performed based on the difference signal between the lightness signals on the reference side and the reference side calculated in step 45, and when it is determined in step 52 that all the correlation calculations have been completed, the process proceeds to step 53. In step 53, the distance Dh when a substantially point light source is used is calculated.

In step 54, it is determined whether or not the distance Dj calculated in step 49 according to the conventional triangulation principle and the distance Dh calculated in step 53 match. If they match, one of them is determined as the distance to the measurement target, and the distance measuring operation is ended. If they do not match, the process proceeds to step 55. In step 55, for example, it is determined whether or not the peak value of the reference-side brightness signal exceeds the threshold value Vth.
If it exceeds, it is determined that the contrast of the mirror surface is stronger even if the measurement object is a mirror surface or the mirror surface and the non-mirror surface are mixed, and the process proceeds to step 56, and the distance Dh is selected as the distance to the measurement object. To complete the distance measurement operation. on the other hand,
If it does not exceed, it is determined that the contrast of the non-mirror surface is stronger even if the measurement target is not a mirror surface, or the mirror surface and the non-mirror surface are mixed, and the process proceeds to step 57, where the distance to the measurement target is determined by conventional triangulation. Distance D calculated by the principle
Select j to end the distance measuring operation.

In the above embodiment, the judgment as to whether or not it is a mirror surface is made by using the brightness signal itself output from the light receiving section, but it may be made by using the difference signal of the brightness signals. Needless to say. Further, in addition to the brightness signal or the difference signal, the absolute value of the spatial differential value of these signals can be used to determine whether or not it is a mirror surface.

That is, the spatial differential value 72 of the lightness signal or the difference signal thereof also has a clear peak as shown in FIG. 16A when the measurement target is a mirror surface, and a clear peak when the measurement target is a non-mirror surface.
There is no clear peak as shown in 16 (B). Therefore, even if the spatial differential value of the brightness signal or its difference signal is used,
By setting an appropriate threshold range Vth ′, it is possible to determine whether the measurement target is a mirror surface.

According to this embodiment, the distance to the measuring object can be accurately calculated regardless of whether the measuring object is a mirror surface or whether the mirror surface and the non-mirror surface are mixed. The distance measuring mechanism for the distance Dj based on the conventional triangulation principle is shown in FIG.
17 can be performed with the point light source turned off. However, as shown in FIG. 17, a conventional distance measuring device 80 dedicated to distance measurement by triangulation is provided, and a computer is provided via the A / D converter 81. The configuration may be such that data is input to 36. In the case of the distance measuring device having the two substantially point light sources shown in FIG. 7 which is an embodiment of the second invention, one distance measuring device may also be used, and as in FIG. 17, it is dedicated to triangulation. It goes without saying that the distance measuring device 80 may be separately provided.

Note that, for example, as shown in FIG. 18, the reference side light receiving section 33 is divided into a plurality of areas LZ1 to LZ3, and the reference side light receiving section 34 also has the areas LZ1, LZ2, LZ of the reference side light receiving section 33.
It is divided into regions RZ1, RZ2, RZ3 corresponding to 3 respectively. Then, the corresponding divided regions LZ1 and RZ
1. If the distance calculation is performed for each of LZ2 and RZ2, LZ3 and RZ3, even if there are multiple measurement targets and the distances to each measurement target are different, the distance to each measurement target can be calculated. You can

Next, a configuration of the distance measuring device of the present invention applied to, for example, an obstacle detection system of an automobile will be described.
This will be described with reference to 19. In FIG. 19, the approximate point light source 35 is
It is driven by the LED driver 37 according to a command from the computer 36. The reference side lightness signal and the reference side lightness signal generated from the reference side light receiving section 33 and the reference side light receiving section 34 are input to the computer 36 through the respective A / D converters 38 and 38 'and stored via the data bus. Written to device 39. In the computer 36, a storage device via a data bus
Data is exchanged with 39, and distance calculation as shown in the flowcharts of FIGS. 20 and 21 is executed to calculate the distance and direction of the obstacle. The distance calculation operation up to steps 61 to 77 of the flowcharts of FIGS. 20 and 21 is the same as that of the flowcharts of FIGS. 13 and 14. Then, when the distance Dj or Dh calculated based on the judgment of step 74 or step 75 is selected, the computer 36 finally executes the calculated data through the data bus by the execution of step 78, and the display device 90 as a display means. Send to. As shown in the figure, the display device 90 has a display unit 91 that displays the position of the obstacle (the dark portion in the upper center) with the center of the fan as the host vehicle position. .

According to such a system, since the position (distance and direction) of the obstacle existing around the automobile can be notified to the driver on the screen, the driver can easily grasp the position information of the obstacle. it can. In the distance calculation operation of this system, it is determined whether the measurement target is a mirror surface (step
It goes without saying that the step 75) may be performed by using the difference signal of the brightness signal or the spatial differential value of the brightness signal.

A cylindrical lens may be used or an optical filter may be added to the optical system of each of the above-described embodiments. As shown in FIG. 22, when the cylindrical lens 51 is used as the optical system, the detection range becomes wider in the vertical direction (the direction of the arrow in the figure), and the same effect as that of lengthening the light receiving portion can be obtained. When the measurement target is tilted in the vertical direction, the vertical direction in which the reflected light from the measurement target from the point light source is returned changes, so by using the cylindrical lens 51 in the optical system, the measurement target is tilted in the vertical direction. Even if it is on, distance measurement is possible.

Further, as shown in FIG. 22, by adding an optical filter 52 in front of the light receiving portions 33 and 34, which cuts light other than the wavelength of the light from the point light source, light other than the point light source is added. Since the influence due to can be reduced, the S / N ratio of the brightness signal can be further improved. Although the cylindrical lens 51 and the optical filter 52 are shown together in FIG. 22,
It goes without saying that either one may be provided.

[0061]

As described above, according to the present invention, even if the surface of the object to be measured is a mirror surface, distance measurement can be performed by utilizing the principle of triangulation, and even if the object to be measured is a mirror surface and is unspecified. Can measure distance. Further, by using two light sources, distance measurement can be performed even if the measurement target is a curved mirror.

Further, by providing the function of determining whether or not the measuring object is a mirror surface based on the brightness signal, the distance can be measured regardless of whether the measuring object is a mirror surface or not. Reduces the effect of outside light by calculating the parallax using the difference signal of the brightness signal or by entering the light into the light receiving part through an optical filter that cuts light other than the wavelength of the irradiation light of the light source. As a result, the S / N is improved and the distance measurement accuracy can be improved.

Further, by dividing the light receiving portion into a plurality of areas and performing distance measurement for each area, distance measurement can be performed even if there are a plurality of measurement objects having different distances. If a cylindrical lens is used in the optical system, distance measurement is possible even if the measurement target is tilted in the vertical direction. If the obstacle detection device is configured by providing display means in the triangulation type distance measuring device of the present invention, it becomes possible to inform the driver of obstacles existing in the vicinity of, for example, an automobile.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a triangulation type distance measuring device according to a first invention.

FIG. 2 is a configuration diagram of a triangulation type distance measuring device according to a second invention.

FIG. 3 is a configuration diagram of an embodiment of the first invention.

FIG. 4 is an explanatory view of a distance measuring principle of the above-mentioned embodiment when measurement targets are parallel.

FIG. 5 is an explanatory view of the distance measuring principle of the above-mentioned embodiment when the measurement object is not parallel.

FIG. 6 is a flowchart showing a distance measuring operation of the above embodiment.

FIG. 7 is a configuration diagram of an embodiment of the second invention.

FIG. 8 is an explanatory view of a distance measuring principle of the above embodiment.

FIG. 9 is an explanatory view of a distance measuring principle of the above embodiment.

FIG. 10 is a flowchart showing a distance measuring operation of the above embodiment.

FIG. 11 is a flowchart showing a distance measuring operation of an embodiment in which a shift amount is calculated using a difference signal of brightness signals.

FIG. 12 shows a brightness signal, (A) when the light source is turned on, (B)
Is when the light source is off, (C) is the difference signal between when the light is on and when it is off

FIG. 13 is a flowchart showing a distance measuring operation of an embodiment having a function of determining whether or not it is a mirror surface

FIG. 14 is a flowchart following FIG. 13.

FIG. 15 is a brightness signal, (A) when the measurement target is a mirror surface, (B) when the measurement target is a non-mirror surface

FIG. 16 is a spatial differential value of the lightness signal, where (A) is the case where the measurement target is a mirror surface, and (B) is the case where the measurement target is a non-mirror surface.

FIG. 17 is a configuration diagram of an embodiment in which a dedicated triangulation distance measuring device is separately provided.

FIG. 18 is an explanatory diagram of an embodiment in which the light receiving unit is divided into a plurality of areas and distance measurement is performed for each area.

FIG. 19 is a configuration diagram showing an embodiment of an obstacle detection device.

FIG. 20 is a flowchart showing the obstacle detection operation of the above embodiment.

FIG. 21 is a flowchart that follows FIG. 20.

FIG. 22 is an explanatory diagram of an embodiment that uses a cylindrical lens or an optical filter.

FIG. 23 is an explanatory diagram of a conventional example of a passive triangulation type distance measuring device.

FIG. 24 is an explanatory diagram of a distance measuring principle of the conventional example as above.

FIG. 25 is an explanatory diagram of a conventional device that measures a distance to a plane mirror.

FIG. 26 is an explanatory diagram of a conventional device that measures a distance to a plane mirror.

FIG. 27 is an explanatory diagram of another conventional device that measures a distance to a plane mirror.

[Explanation of symbols]

 31 First optical system 32 Second optical system 33 Reference side light receiving section 34 Reference side light receiving section 35, 41 Point light source 36 Computer 37 LED driver 38 A / D converter 39 Storage device 40 Plane mirror 42 Curved mirror 51 Cylindrical lens 52 Optical filter 90 Display 91 Display

Claims (13)

[Claims] 1. A light source for irradiating a measurement target with light, first and second optical systems into which light from the measurement target respectively enters, and an intensity distribution state of light received via the first optical system. And a reference-side light receiving unit that outputs a second lightness signal indicating the intensity distribution state of the light received via the second optical system, and a first light-receiving unit that outputs a first lightness signal that indicates Measuring means for comparing the lightness signal and the second lightness signal with each other to measure the deviation amount of the light receiving position of the reference side light receiving means with respect to the light receiving position of the surface of the reference side light receiving means, and the deviation amount measured by the measuring means. The first distance calculating means for calculating the distance to the virtual image of the light source using the principle of triangulation and the distance to the virtual image calculated by the first distance calculating means are D
k, and a distance from the light source to the optical system is Doff, the distance Dh to the measurement object is calculated by the following formula: Dh = (Dk-Doff) / 2 A triangulation type distance measuring device characterized in that 2. A first and a second light source for irradiating a measurement target with light, a first and a second optical system for receiving light from the measurement target respectively, and light reception through the first optical system. Reference side light receiving means for outputting a first brightness signal indicating the intensity distribution state of the received light, and reference side light receiving for outputting a second brightness signal indicating the intensity distribution state of the light received via the second optical system. Means for comparing the first lightness signal and the second lightness signal for each irradiation light of each light source, and irradiating each light source with the deviation amount of the light reception position of the reference side light reception means with respect to the light reception position of the surface of the reference side light reception means. First distance calculation for calculating the distance to the virtual image of each light source by using the principle of triangulation based on the deviation amount of each light source with respect to the irradiation light measured by the measurement means Means and the distance to each virtual image calculated by the first distance calculation means is D
where k ₁ and Dk ₂ and Doff ₁ and Doff ₂ are the distances from the first and second light sources to the optical system, the distance Dh to the measurement target is Dh = (Dk ₂ · Doff ₁ −Dk ₁・ Doff ₂ ) /
_{(Dk 1 -Doff 2 -Dk 2 +} Doff 1) triangulation distance measuring apparatus characterized by being configured with a second distance calculating means for calculating, for the arithmetic expression. 3. A determination means for determining whether or not the measurement object is a mirror surface based on the brightness signal of at least one of the both light receiving means, and when the measurement object is not a mirror surface, the light source is turned off. The value calculated by the first distance calculation means based on the obtained displacement amount is set as the distance to the measurement target, and when it is determined that the measurement target is a mirror surface, the second
The triangulation type distance measuring device according to claim 1 or 2, wherein the value calculated by the distance calculating means is the distance to the object to be measured. 4. The determining means determines whether or not there is a peak value higher than a preset threshold value in the brightness signal, and when there is a peak value higher than the threshold value, the measurement target is determined to be a mirror surface and is higher than the threshold value. The triangulation type distance measuring device according to claim 3, wherein the measurement target is not a mirror surface when there is no peak value. 5. The determining means calculates the difference between the values of the lightness signal when the light source is turned on and when the light source is turned off, and determines whether the calculated difference signal has a peak value higher than a preset threshold value. The triangulation distance measurement according to claim 3, wherein when the difference signal has a peak value higher than the threshold value, the measurement target is determined to be a mirror surface, and when there is no peak value higher than the threshold value, the measurement target is not a mirror surface. apparatus. 6. The determination means calculates a spatial differential value of a lightness signal, determines whether or not a peak value higher than a preset threshold value exists in the absolute value of the calculated spatial differential value, and the peak value is higher than the threshold value. 4. The triangulation type distance measuring apparatus according to claim 3, wherein the measuring object is determined to be a mirror surface when a peak value exists, and the measuring object is not a mirror surface when a peak value higher than a threshold value does not exist. 7. The peak value higher than a threshold value preset to the absolute value of the calculated spatial differential value by calculating the spatial differential value of the difference signal between the values of the lightness signal when the light source is turned on and when the light source is turned off. 4. It is configured to determine whether or not exists, determine that the measurement target is a mirror surface when a peak value higher than the threshold value exists, and determine that the measurement target is not a mirror surface when there is no peak value higher than the threshold value. Triangulation range finder. 8. The measuring means compares the difference signal between the values of the first brightness signal when the light source is turned on and off and the difference signal between the values of the second brightness signal when the light source is turned on and off. The triangulation type distance measuring device according to any one of claims 1 to 7, wherein the triangulation type distance measuring device is configured to measure a shift amount of a light receiving position. 9. The direction of the object to be measured, wherein Rd is the distance between the light receiving position and the intersection of the optical axis of the first optical system on the surface of the reference side light receiving means, and f is the focal length of the first optical system. Angle θ
9. The triangulation type distance measuring device according to claim 1, further comprising a direction angle calculating means for calculating h by an arithmetic expression of θh = atan (f / Rd). 10. The triangulation type distance measuring device according to claim 1, wherein a cylindrical lens is used for both optical systems. 11. The triangulation according to claim 1, wherein an optical filter that cuts light other than the wavelength of the irradiation light of the light source is installed between the measurement target and the light receiving means. Distance measuring device. 12. A triangulation type distance measuring device according to any one of claims 1 to 11, and display means for inputting and displaying position information of a measurement target obtained by the triangulation type distance measuring device. An obstacle detection device characterized by being configured as follows. 13. The obstacle detection device according to claim 12, wherein the display unit has a fan-shaped display unit and is configured to display a position of a measurement target with a main position of the fan as a position of the distance measuring device.