JP2001059724A - Optical axis detector - Google Patents

Abstract

(57) [Problem] To provide an optical axis detection device capable of detecting a vertical optical axis shift even when a radar head that scans a laser beam in a horizontal direction is used. A reflector 201 provided in a vertical direction and a reflector 202 provided in an oblique direction are irradiated by a laser device, and a position of strong reflection intensity from the reflector in the vertical direction is set as a center position, By calculating the distance between the positions of both ends of the weak reflection intensity from the reflector and the center, the irradiation angle in the vertical direction is detected by using Expression (1). For example, FIG.
As shown in (1), if the irradiation angle of the laser radar is higher than the horizontal, the irradiation range on the target board is offset upward, and a difference (x1> x2) occurs in the distance from the center. Since the value of this distance corresponds to the deviation angle Ψ (irradiation angle) from the horizontal plane, the deviation angle Ψ in the vertical direction can be obtained by obtaining this value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the optical axis of laser light in a radar apparatus using laser light, and more particularly to an apparatus for detecting optical axis deviation in both horizontal and vertical directions only by scanning in the horizontal direction.

[0002]

2. Description of the Related Art A conventional optical axis detecting device is disclosed in
There is one disclosed in Japanese Patent No. 29536. In this method, a reflector is arranged at a predetermined position in front of a radar head, two-dimensionally scans a laser beam from the radar head,
The optical axis deviation in the vertical direction is determined by detecting the reflection from the road surface, and the optical axis deviation in the horizontal direction is detected by detecting the reflection from the reflector.

[0003]

In the above-mentioned conventional example, the laser beam is scanned two-dimensionally to determine the optical axis deviation in both the vertical direction and the horizontal direction. When a radar head that scans only laser light is used, there is a problem that the optical axis deviation in the horizontal direction can be detected, but the optical axis deviation in the vertical direction cannot be detected.

The present invention has been made to solve the problems of the prior art as described above. Even when a radar head that scans a laser beam in the horizontal direction is used, the optical axis deviation in the vertical direction can be reduced. It is an object of the present invention to provide an optical axis detecting device capable of detecting.

[0005]

In order to achieve the above object, the present invention is configured as described in the appended claims. That is, according to the first aspect of the present invention, a target board in which two or more rectangular reflectors made of a substance having a higher reflectance than the board are installed on the board at different angles, When the target board is irradiated with laser light from the radar device, a second beam centered on a position where the reflection intensity is equal to or higher than the first threshold and the reflection intensity is lower than the first threshold. Computing means for determining both end positions in a range equal to or greater than a threshold value and smaller than the first threshold value, and calculating a vertical irradiation angle based on a difference in distance from the center to each end. Make up.

As described above, according to the present invention, when a target board is irradiated with laser light from a radar apparatus for adjusting the optical axis, a reflector is installed obliquely around a position where the reflection intensity is extremely strong. The irradiation angle in the vertical direction is detected by calculating the distance between the positions of both ends of the reflection from the center and the center. For example, as shown in FIG. 2 described below, when the irradiation angle of the laser radar faces upward from the horizontal,
Since the irradiation range on the target board is shifted upward, a difference (x1> x2) occurs in the distance from the center. Since the value of this distance corresponds to the shift angle 水 from the horizontal plane, the vertical shift angle Ψ (irradiation angle from the horizontal plane, Equation 1 below) can be obtained by obtaining this value. The horizontal optical axis deviation can be easily obtained as a horizontal angle difference from the position where the reflection intensity is extremely strong.

[0007] The invention described in claim 2 is the first invention.
In the vertical direction based on the values of the angles (φ1, φ2) formed by the respective lines with the radar device and the center as reference axes instead of the distances (x1, x2) from the center to both ends. The configuration is such that an irradiation angle (formula 2 below) is obtained.

The invention described in claim 3 shows a specific configuration example of the target board, and corresponds to, for example, an embodiment shown in FIG. 2 described later.

The invention described in claim 4 shows another specific configuration example of the target board, and corresponds to, for example, an embodiment shown in FIG. 6 described later.

[0010]

According to the present invention, even when a radar head that scans laser light in the horizontal direction is used, an effect that the optical axis deviation in the vertical direction can be easily detected is obtained.

[0011]

1 to 5 are views showing an embodiment of the present invention. FIG. 1 is an overall view of an optical axis detection device, and FIG. 1A is a diagram of the optical axis detection device as viewed from above,
(B) is the figure seen from the lateral direction. In FIG. 1, reference numeral 1 denotes a laser radar device, which is mounted on a vehicle 10.
Reference numeral 11 denotes a semiconductor laser, 12 denotes a mirror that scans laser light from the semiconductor laser 11 in the horizontal direction, and 13 denotes a motor that rotates the mirror 12. By changing the angle of the reflecting surface of the mirror 12 by the motor 13, the laser beam can be scanned in a predetermined scanning angle unit in the horizontal direction within a range of ± φ ° with the front of the laser radar device 1 set to 0 °. Reference numeral 14 denotes a light receiving element, and a light receiving lens 15
And receives the laser light incident thereon. Then, the control device 16 determines the light emission timing of the semiconductor laser 11, the motor 1
3 and scanning angle of mirror 12 and light receiving element 1
This is a device for controlling the light receiving timing from the light source 4, and calculates a vertical optical axis shift amount, which will be described later, and outputs the shift amount to the display device 17. The display device 17 is, for example, a liquid crystal display device or the like, and displays the above-described shift amount and the like. FIG.
Ψ in (b) is the vertical deviation angle (the angle between the horizontal plane and the laser beam irradiation axis).

Reference numeral 20 denotes a target board, which is a vehicle 10
Is arranged so that the surface is parallel to the vehicle 10 (laser radar device 1) and the surface is perpendicular to the ground. Reference numeral 21 denotes a holder, which has a mechanism (not shown) for holding the target board 20 and moving the target board 20 in the vertical direction. Reference numeral 22 denotes an optical linear sensor as shown in FIG. 3 described later, which is installed in a hole (203 in FIG. 2 described later) of the target board 20. A control unit 23 controls a mechanism for moving the target board 20 in the vertical direction based on the output from the optical linear sensor 22.

FIG. 2 shows a state in which the target board 20 is mounted on the vehicle 10.
It is the figure seen from the side. The target board 20 includes a reflector 201 extending in a vertical direction on a member having a low reflectance with respect to the laser beam (for example, a matte black painted plate or the like ), and an angle θ.
, A reflector 202 extending from the upper right to the lower left and intersecting with the reflector 201 is attached. The length to both ends of the reflector 202 extending on both sides of the reflector 201 is the same. That is, the reflector 202 and the reflector 201
And cross at the center. And the reflector 201
A hole 203 is provided at the intersection of the target and the target board 20, and the optical linear sensor 22 is installed at this portion. Reference numeral 210 denotes an irradiation range of the laser beam when the laser beam is scanned in the horizontal direction. The laser beam is irradiated as a rectangular light beam having a narrow width in the vertical direction and the same width in the vertical direction of the irradiation range 210, and is scanned in the horizontal direction. H is the height from the ground surface at the vertical center position of the laser beam irradiation range, and h is the height from the ground surface at the vertical center position of the laser radar device 1 mounted on the vehicle (the height of the radar irradiation axis). Is shown). The reflectors 201 and 20
The reflectivity of the two may be the same or different, but a reflectivity higher than the target board 20 is used. As the reflectors 201 and 202, for example, a reflector using fine glass beads can be used.

FIG. 3 is a sectional view of an example of the optical linear sensor 22. In FIG. 3, reference numeral 221 denotes a light receiving element, and reference numeral 222 denotes a lens, which can detect a light receiving position of incident light. Such an optical linear sensor 22 is inserted into the hole 203 of the target board 20 (the intersection of the reflectors 201 and 202).
Then, the lens 222 is inserted toward the vehicle 10.

Prior to the description of the method of detecting the optical axis shift amount, the setting of the initial position of the target board 20 before starting the optical axis detection will be described. The target board 20
Is installed in front of the laser radar device 1. The distance between the target board 20 and the laser radar device 1 is L. First, using the control unit 23, the target board 20
The position of the target board 20 in the vertical direction is adjusted so that the position of the optical linear sensor 22 provided at the center and the center position (semiconductor laser 11) of the laser radar device 1 are at the same height. That is, after the control unit 23 is set to the adjustment mode by a switch operation (not shown), a laser light source whose optical axis is adjusted in the horizontal direction separately from the semiconductor laser 11 (not shown, the height is the center of the laser radar device 1 of the vehicle) (Located near the laser radar device 1 at the same height as the position). If the laser beam does not hit the hole 203, the optical linear sensor 22 does not receive the light. Therefore, the mechanism of the holder 21 is controlled to move the target board 20 upward or downward. When a laser beam is received by the optical linear sensor 22, the optical linear sensor 2 depends on the angle of the incident laser beam.
2 is changed, the target board 20 is set so that the laser beam is incident on the center position of the optical linear sensor 22.
Adjust the vertical position of. Thereby, the position of the optical linear sensor 22 (the reflector 201 of the target board 20)
And the position of the laser light source are at the same height, so that the reflector 20 of the target board 20
The position of the intersection of 1 and 202 and the semiconductor laser 11 of the laser radar device 1 of the vehicle are adjusted to the same height (h in FIG. 2).

The position of the target board 20 in the vertical direction can be adjusted using the laser radar device 1 of the vehicle instead of the laser light source for adjustment. In other words, the mounting angle of the laser radar device 1 of the vehicle is not extremely deviated even in the state where the laser radar device 1 is mounted first, and is within a range of about several degrees from the horizontal plane. And since the laser beam has a width up and down,
If it is out of the above range, a horizontal component exists in the laser beam. Therefore, if the optical linear sensor 22 provided on the target board 20 detects a horizontal component in the laser beam, the height (h in FIG. 2) of the semiconductor laser 11 of the laser radar device 1 can be detected. Using this h, the position can be adjusted according to the same principle as described above.

Next, FIG. 4 is a flowchart showing the processing contents of the control device 16 provided in the laser radar device 1. Hereinafter, a method of detecting the optical axis shift amount will be described with reference to FIG. First, in step S1, laser light is emitted. That is, as shown in FIG.
In the range of φ, while controlling the motor 13 for moving the reflection surface of the mirror 12 at every predetermined scanning angle, the semiconductor laser 11 is controlled to emit a pulsed laser beam at each scanning angle, and the laser beam is controlled. Scan once in the horizontal direction.

In step S2, reflected light is detected. In the case of the irradiation range as shown in FIG. 2, the characteristic of the received light intensity as shown in FIG. 5A is obtained. As described above, the laser beam is irradiated as a rectangular light beam having a narrow width in the vertical direction and the same as the vertical width of the irradiation range 210, and is scanned in the horizontal direction. When the light strikes the oblique reflector 202, the reflection intensity is small because the reflection range is narrow, and when the light strikes the vertical reflector 201, the reflection intensity is large because the reflection range is wide. In FIG. 5A, a portion where the light reception intensity exists in a plateau shape corresponds to light reception from the oblique reflector 202, and a portion rising in a peak shape corresponds to light reception from the reflector 201 in the vertical direction. . That is, when scanning is sequentially performed toward the target board 20, the light receiving intensity is very low in a portion where there is no reflector at first. When the light reflected from the oblique reflector 202 is received, the received light intensity becomes a certain value and continues to be a certain value. In the portion where the reflected light from the vertical reflector 201 is received, the received light intensity is significantly increased. After that, the light intensity of the reflected light from the oblique reflector 202 becomes the intensity again, and finally reaches the portion without the reflector.

Next, in step S3, it is determined whether or not there is data of the received light intensity equal to or more than a predetermined first threshold value Th1. Here, the first threshold value Th1 is such a value that the vertical reflector 201 is detected but the reflector 202 is not detected. If "NO" in the step S3, that is, if the deviation angle in the horizontal direction or the vertical direction is large and the reflected light from the reflector 201 cannot be obtained, the display 17 indicates "the target is appropriate" in a step S10. Is not installed in the target board 20 "to prompt the inspector to adjust the position of the target board 20. Step S3
Is "YES" in step S4, the irradiation angle of the data position having the light receiving intensity equal to or greater than the first threshold value Th1 is set to φ0, and the laser beam irradiation reference position by the mirror 12 is initialized. That is, the laser radar device 1 is set so that this position is in front. This allows the horizontal illumination angle to be calibrated. FIG. 5B is a diagram illustrating the reflection intensity of FIG. 5A in a state where the irradiation reference position is initialized as described above.

Next, in step S5, it is determined whether or not the absolute value of φ0 is equal to or smaller than a predetermined value. If the absolute value is larger than the predetermined value (“NO”), the same processing as described above is performed in step S10. Do. Here, the case where the value is larger than the predetermined value is as follows.
This is a case where the displacement in the horizontal direction is too large, and accurate φ1 and φ2 cannot be detected in step S7 described later, and the displacement in the vertical direction cannot be measured. If “YES” in the step S5, it is determined in a step S6 whether or not the data of the reflection intensity smaller than the first threshold value Th1 and larger than the second threshold value Th2 (Th1> Th2) is obtained. Determine. Here, the second threshold value Th2 is a threshold value for detecting the oblique reflector 202. Here, in the case of “NO”, the irradiation angle of the laser beam is deviated in the vertical direction so that the reflected light from the oblique reflector 202 cannot be received. Is not in the recognizable vertical range ", and prompts the inspector to adjust the orientation of the laser radar device 1 (see FIG. 1B).

On the other hand, if "YES" in the step S6, the angles φ1 and φ2 at both ends of the portion where the received light intensity is equal to or more than the second threshold value Th2 (the center position: φ0 Angle). Here, φ1 is the angle between the upper end of the laser light irradiation range and the position where the reflector 202 crosses, and φ2 is the angle between the lower end of the laser light irradiation range and the position where the reflector 202 crosses. That is, the angle φ1 corresponds to the distance x1 in FIG.
Corresponding to FIG. 5B is a diagram showing the angles φ1 and φ2 after the position of φ0 is initialized to the front (step S4).

As shown in FIG. 2, the laser radar device 1
If the irradiation angle is higher than the horizontal, the irradiation range on the target board is shifted upward, and a difference (x1> x2) occurs in the distance from the center. If the irradiation angle is lower than the horizontal, x1 <x2. As described above, since the value of the distance corresponds to the deviation angle Ψ from the horizontal plane, the vertical deviation angle Ψ
(Irradiation angle from horizontal plane, Equation 1 described later) can be obtained. The horizontal optical axis deviation can be easily obtained as a horizontal angle difference from the position where the reflection intensity is extremely strong.

For the sake of simplicity, the following description is made by replacing the angle φ with the distance x. When the angle φ is replaced with the distance x, there is a correspondence as shown in FIG. Note that L is the distance from the laser radar device 1 to the reflector, and can be easily obtained by the laser radar device 1. x1 = L
From sinφ1, x2 = Lsinφ2, the deviation between the height H of the center position (irradiation axis) of the laser irradiation range and the height h of the radar center position is as follows: It is represented by Therefore, the optical axis angle Ψ in the vertical direction (angle with respect to the horizontal plane: shift angle) is as follows: Ψ = tan ⁻¹ [(1/2) (x1−x2) tan θ / L] (Equation 1) The above calculation is performed in step S8, and the vertical deviation angle Ψ is displayed on the display 17 in step S9.

If the angle of the laser radar device 1 is adjusted so that the deviation angle Ψ becomes 0, H = h and x1 = x2. Also, by setting the laser radar device 1 so that the position of φ0 is recognized as the front of the vehicle as described above,
Horizontal calibration can be performed simultaneously.

In the above equation (1), the shift angle Ψ is displayed by using the horizontal distance x, but it can be displayed by using the angles φ1 and φ2. That is, by using φ1 and φ2 used for calculating x1 and x2, the optical axis angle Ψ (shift angle) in the vertical direction can be obtained as follows. The deviation (Hh) between the height H of the laser irradiation axis and the height h of the radar center position is Hh = (1/2) (tanφ1-tanφ2) tanθ Therefore, the optical axis angle in the vertical direction Ψ (the angle with respect to the horizontal plane) : Shift angle) is as follows: Ψ = tan ^-1 [(1/2) (tanφ1-tanφ2) tanθ] (Equation 2).

Next, a second embodiment will be described. FIG. 6 is a diagram illustrating an example of the target board used in the second embodiment. In FIG. 6, the oblique reflector is divided into two, 204 and 205, each of which extends linearly from the vertical reflector 201 to the opposite side in an obliquely upward direction and an obliquely downward direction. If the measurement resolution in the horizontal direction of the laser radar device 1 is the same, the smaller the tan θ, the finer the resolution in the vertical direction. Therefore, when a more precise adjustment is desired, the target as shown in FIG.
Can be reduced. In FIG. 6, the height H = (1/2) [(x1
+ X2) tan θ + y] Height h of laser center position h = x2 tan θ + (y / 2) Therefore, laser irradiation axis height H and radar center position height h
(H−h) = (1/2) [(x1 + x2) tan θ + y] − [x2 tan θ + (y / 2)] = (1/2) (x1−x2) tan θに な る is the same as the equation (1) as described below. Ψ = tan ⁻¹ [(1/2) (x1−x2) tan θ / L] where y is the distance between the reflectors 204 and 205 in contact with the reflector 201 (see FIG. 6).

[Brief description of the drawings]

FIG. 1 is an overall view of an optical axis detection device according to a first embodiment of the present invention, where (a) is a view of the optical axis detection device from above and (b) is a view of the optical axis detection device from a lateral direction.

FIG. 2 shows a front view of a target board (laser radar device 1).
Side).

FIG. 3 is a cross-sectional view of the optical linear sensor.

FIG. 4 is a flowchart showing calculation contents in the control device.

FIG. 5 is a reflection intensity characteristic diagram when the target board is irradiated with the laser radar device 1.

FIG. 6 is a diagram showing a target board used in a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Laser radar device 10 ... Vehicle 11 ... Semiconductor laser 12 ... Mirror 13 ... Motor 14 ... Light receiving element 15 ... Light receiving lens 16 ... Control device 17 ... Display device 20 ... Target board 21 ... Holder 22 ... Optical linear sensor 23 ... Control Section 201: Reflector in the vertical direction 202: Reflector in the oblique direction 203 ... Hole 210: Irradiation range of laser light 221: Light receiving element 222: Lenses 204, 205
... Diagonal reflector

Claims (4)

[Claims] 1. A target board on which a rectangular reflector made of a substance having a higher reflectance than the board is installed at two or more different angles, and a target device comprising: a radar device for adjusting an optical axis; When the board is irradiated with a laser beam, the reflection intensity is centered on the position where the reflection intensity is equal to or higher than the first threshold value, and the reflection intensity is equal to or higher than the second threshold value which is smaller than the first threshold value. Calculating means for obtaining both end positions in a range smaller than the threshold value and obtaining an irradiation angle in a vertical direction based on a value of a distance from the center to each end. apparatus. 2. A target board having a rectangular reflector made of a substance having a higher reflectivity than the board at two or more different angles on a board, and a target device comprising: a radar device for adjusting an optical axis; When the board is irradiated with a laser beam, the reflection intensity is centered on the position where the reflection intensity is equal to or higher than the first threshold value, and the reflection intensity is equal to or higher than the second threshold value which is smaller than the first threshold value. Calculating means for determining both end positions in a range smaller than the threshold value, and obtaining an irradiation angle in the vertical direction based on a value of an angle formed between the respective ends with the line connecting the radar device and the center as a reference axis. An optical axis detection device comprising: 3. The target board according to claim 1, wherein the first reflector has a rectangular shape provided with a longitudinal direction extending along a vertical direction, and the center of the first reflector is coincident with the center of the first reflector. The optical axis detection device according to claim 1, further comprising a rectangular second reflector that intersects the reflector at a predetermined angle. 4. The target board according to claim 1, wherein the first reflector has a rectangular shape provided in a longitudinal direction along the vertical direction, and an obliquely upward direction from a position within an upper half of the longitudinal direction of the first reflector. And a third reflector linearly extending obliquely downward in a direction opposite to the second reflector from a position within a lower half of the longitudinal direction of the first reflector. Reflector and
The optical axis detection device according to claim 1 or 2, further comprising: