JP7635687B2 - Distance measuring device - Google Patents

Description

This disclosure relates to a distance measuring device.

There are distance measuring devices that emit a transmitted wave and detect the reflected wave from an object to determine the distance to the object and its relative speed. In this type of distance measuring device, a rotating deflection mirror is generally used to deflect the transmitted wave for scanning. The transmitted wave output from the transmitter is reflected by the deflection mirror and emitted in a direction according to the rotation angle of the deflection mirror, thereby scanning a preset scanning range.

Patent Document 1 discloses a lidar device that performs two-dimensional scanning by deflecting and scanning light beams output from two transmitters in the vertical direction by two oscillatingly driven plane mirrors and in the horizontal direction by one rotationally driven polygon mirror. In this lidar device, a first light beam output from one transmitter is reflected by the first plane mirror toward the polygon mirror, and a second light beam output from the other transmitter is reflected by the second plane mirror toward the polygon mirror. The first light beam and the second light beam are then reflected by different reflecting surfaces of the polygon mirror and are each emitted into a different scanning range.

U.S. Pat. No. 10,324,170

In recent years, there has been a demand for even smaller distance measuring devices. However, after detailed consideration by the inventors, it was found that the configuration disclosed in Patent Document 1 has two transmitters, two oscillating mirrors, and two oscillating motors for driving the oscillating mirrors, resulting in a problem that the overall size of the distance measuring device becomes large.

One aspect of the present disclosure is to provide technology that can reduce the overall size of a distance measuring device.

One aspect of the present disclosure is a distance measuring device (1) that includes a measurement unit (2) that irradiates a transmission wave and detects a reflected wave from an object irradiated with the transmission wave. The measurement unit includes one each of a transmission unit (11), a reception unit (12), an oscillating scanner (20), and a polygon scanner (30). The transmission unit is configured to output a transmission wave. The reception unit is configured to detect a reflected wave. The oscillating scanner includes an oscillating mirror (21) that reflects the transmission wave and the reflected wave, and an oscillating motor (22) configured to drive the oscillating mirror to oscillate around an oscillating axis (221) extending in a first direction. The polygon scanner includes a polygon mirror (31) having a plurality of reflecting surfaces that reflect the transmission wave and the reflected wave, and a rotary motor (32) configured to rotate the polygon mirror around a rotary axis (321) extending in a second direction perpendicular to the first direction. The transmitter, receiver, oscillating mirror, and polygon mirror are arranged so that the transmission wave output from the transmitter is reflected by the oscillating mirror and polygon mirror in that order and emitted within a pre-set scanning range, and the reflected wave is reflected by the polygon mirror and oscillating mirror in that order and received by the receiver.

With this configuration, the size of the entire distance measuring device can be reduced by providing one each of a transmitter, receiver, oscillating scanner, and polygon scanner.

FIG. 2 is a perspective view showing the appearance of a lidar device. FIG. FIG. 2 is a perspective view showing a schematic configuration of a measurement unit. 2 is a schematic diagram showing the optical path of a light beam output from a light projecting unit until it is incident on a reflecting surface of a polygon mirror. FIG. FIG. 2 is a schematic diagram of the measurement unit as viewed from above. FIG. 2 is a schematic diagram of the measuring unit as viewed from the front. FIG. 4 is a schematic diagram of the measurement unit as viewed from the right. FIG. 11 is a block diagram showing a schematic configuration of a lidar device according to a second embodiment. 11A and 11B are diagrams illustrating an example of correcting a control value of a swing motor according to error information in an error correction process. 10 is a flowchart of an error correction process executed by a control unit in the second embodiment. FIG. 13 is a block diagram showing a schematic configuration of a lidar device according to a third embodiment. 13 is a flowchart of a gradient correction process executed by a control unit in the third embodiment. 2 is a schematic diagram showing an example of an arrangement of a transmitting/receiving unit, an oscillating scanner, a polygon scanner, and a folding mirror. FIG. 2 is a schematic diagram showing an example of an arrangement of a transmitting/receiving unit, a swinging scanner, and a polygon scanner. FIG. 2 is a schematic diagram of a lidar device equipped with a breathing filter, viewed from the optical window side with the optical window removed.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.
[1. First embodiment]
[1-1. Overall configuration]
The LIDAR device 1 shown in Fig. 1 is a distance measuring device that measures the distance and relative speed to an object by emitting a transmission light and receiving the reflected light from the object on which the transmission light is irradiated. The LIDAR device 1 is mounted on a vehicle and used to detect various objects present in front of the vehicle. LIDAR is also written as LiDAR. LiDAR is an abbreviation for Light Detection and Ranging.

The lidar device 1 includes a housing 100 , an optical window 200 , and a heat sink 700 .
In the following description, the positive x-axis direction in a three-dimensional orthogonal coordinate system is defined as the right, the negative x-axis direction as the left, the positive y-axis direction as the up, the negative y-axis direction as the down, the positive z-axis direction as the forward, and the negative z-axis direction as the rear. The configuration of the lidar device 1 will be described assuming that in such a three-dimensional orthogonal coordinate system, the width direction of the lidar device 1 is the x-axis direction, the height direction is the y-axis direction, and the depth direction is the z-axis direction, and that the lidar device 1 is installed so that the transmitted light is emitted forward.

The housing 100 is a rectangular parallelepiped box made of resin or metal and having one open side.
The optical window 200 is made of a material that transmits transmitted light and reflected light, and is disposed so as to cover the opening of the housing 100 .

The heat sink 700 is installed on the outer surface of the housing 100 to dissipate heat generated inside the housing 100 and from electronic components mounted on the control board 600 described below. In this embodiment, the heat sink 700 is installed on the top surface of the housing 100.

As shown in FIG. 2, the lidar device 1 includes a control board 600. The control board 600 is a plate-shaped board having an electronic control circuit on which electronic components are mounted. The control board 600 is mounted with a control unit 3, which will be described later. In this embodiment, the control board 600 is installed so that the control unit 3 is sandwiched between the upper surface of the housing 100 and the heat sink 700. Although not shown, at least a portion of the control unit 3 is disposed on the upper surface of the control board 600 so as to face the heat sink 700.

The measurement section 2 is housed in the internal space of the housing 100. The measurement section 2 includes a transmitting/receiving unit 10, an oscillating scanner 20, and a polygon scanner 30.
As shown in Fig. 3, the transmitting/receiving unit 10 is configured as a single unit with a light-projecting section 11 and a light-receiving section 12. The light-projecting section 11 and the light-receiving section 12 are housed inside the transmitting/receiving unit 10. The light-projecting section 11 outputs a transmission light. The light-receiving section 12 receives the reflected light from an object irradiated with the transmission light and converts it into an electrical signal. The measuring section 2 deflects and scans the transmission light output from the light-projecting section 11 with the oscillating scanner 20 and the polygon scanner 30, and emits it within a preset scanning range. Furthermore, the measuring section 2 detects the reflected light with the light-receiving section 12.

The lidar device 1 is provided with one measurement unit 2. That is, the lidar device 1 is provided with one each of a light projecting unit 11, a light receiving unit 12, an oscillating scanner 20, and a polygon scanner 30. A detailed description of the measurement unit 2 will be given later.

Returning to FIG. 2, the control unit 3 is an electronic control device that is mainly composed of a microcomputer equipped with a CPU, ROM, RAM, I/O, etc. (not shown). The various functions of the microcomputer are realized by the CPU executing a program stored in a non-transitive physical recording medium. In this example, the ROM corresponds to the non-transitive physical recording medium that stores the program. Furthermore, the execution of this program executes a method corresponding to the program. Note that some or all of the functions executed by the CPU may be configured in hardware using one or more ICs, etc. Also, the number of microcomputers that make up the control unit 3 may be one or more.

The control unit 3 uses the measurement unit 2 to measure the distance and relative speed of the object that reflected the transmitted light. Specifically, the control unit 3 determines the distance and relative speed of the object based on the difference between the waveform of the electrical signal output from the light receiving unit 12 and the waveform of the transmitted light output by the light projecting unit 11. In another method, the control unit 3 identifies the timing at which the reflected light was received based on the waveform of the electrical signal output from the light receiving unit 12, and determines the distance to the object based on the difference with the timing at which the transmitted light was output by the light projecting unit 11. Note that in addition to the distance and relative speed, the control unit 3 can also determine information about the object, such as the orientation in which the object is located.

[1-2. Measurement section]
As shown in FIG. 3, the measurement section 2 more specifically includes a transmitting/receiving unit 10, an oscillating scanner 20, a polygon scanner 30, and a folding mirror 40.

The light-projecting unit 11 housed in the transceiver unit 10 outputs transmission light. In this embodiment, the light-projecting unit 11 is configured to output transmission light in a direction along the x-axis. The optical path of the transmission light is indicated by a thick arrow.

As shown in FIG. 4, the light projecting unit 11 includes a light source 111 and a lens 112. Note that FIG. 4 shows only the light projecting unit 11 of the transceiver unit 10, and the other components of the transceiver unit 10 are omitted.

The light source 111 is configured to output a plurality of light beams (in other words, transmission light). The optical path of the transmission light is indicated by a thick arrow. A semiconductor laser is used for the light source 111. The light source 111 may be, for example, a multi-stripe semiconductor laser. Furthermore, for example, the light source 111 may be configured to include a plurality of semiconductor lasers to output a plurality of light beams.
The lens 112 is disposed opposite to the light emitting surface of the light source 111. The lens 112 is a lens for shaping the light beam emitted from the light source 111 into a desired shape (width, exit angle, etc.).

Returning to FIG. 3, the light receiving section 12 housed in the transmitting/receiving unit 10 has a light receiving element (not shown) configured to receive reflected light. The light receiving element has an APD array in which multiple APDs are arranged in a row. The APD is an avalanche photodiode. The light receiving element is not limited to an APD, and may be, for example, a single photodiode. Note that, for ease of understanding, FIG. 3 shows only the optical path of one transmitted light, but in reality, multiple transmitted lights are output as shown in FIG. 4.

The oscillating scanner 20 includes an oscillating mirror 21 and an oscillating motor 22 .
The oscillating mirror 21 is a flat plate-like member having a reflecting surface that reflects the transmitted light and the reflected light.
The oscillation motor 22 is configured to drive the oscillation mirror 21 to oscillate around an oscillation shaft 221 extending in a first direction. The first direction is specifically a direction along the z-axis. The oscillation motor 22 includes a rod-shaped shaft member 22a through whose center the oscillation shaft 221 passes, and oscillates the shaft member 22a around the oscillation shaft 221. The rotation timing, rotational movement direction, angular velocity, and the like of the shaft member 22a are controlled by the control unit 3. The oscillation motor 22 may be, for example, a galvano motor. The oscillation mirror 21 is fixed to the shaft member 22a on the surface opposite to the reflecting surface so that the shaft member 22a is aligned along the center line of the surface in the z-axis direction. The oscillation motor 22 is disposed behind the oscillation mirror 21.

The polygon scanner 30 includes a polygon mirror 31 and a rotary motor 32 .
The polygon mirror 31 is a rotating polygonal mirror having a plurality of reflective surfaces that reflect the transmitted light and the reflected light. The polygon mirror 31 has, for example, a prism shape or a truncated pyramid shape, and a reflective surface is arranged on each side. The polygon mirror 31 is configured so that the number of reflective surfaces is five or less. In this embodiment, the polygon mirror 31 has five reflective surfaces, and the polygon mirror 31 has a regular pentagonal prism shape with a regular pentagon on the top and bottom. In other words, the polygon mirror 31 is configured so that all of the multiple reflective surfaces are parallel to the rotation axis 321.

The rotary motor 32 is configured to rotate the polygon mirror 31 around a rotary shaft 321 extending in a second direction perpendicular to the first direction. The second direction is specifically the direction along the y-axis. The rotation timing, rotational movement direction, angular velocity, etc. of the polygon mirror 31 are controlled by the control unit 3. The polygon mirror 31 is fixed to the rotary motor 32 so that the rotary shaft 321 passes through the center of the top and bottom surfaces.

That is, the transmitted light is scanned in a direction along the y-axis (i.e., up and down) by the oscillating scanner 20, and further scanned in a direction along the x-axis (i.e., left and right) by the polygon scanner 30, thereby performing two-dimensional scanning.

The folding mirror 40 is a flat member having a reflective surface that reflects the transmitted light and the reflected light. The folding mirror 40 is arranged on the path of the transmitted light and the reflected light so as to reflect the transmitted light output from the light projector 11 in the direction of the oscillating mirror 21, and to reflect the reflected light reflected by the oscillating mirror 21 in the direction of the light receiver 12. Specifically, the folding mirror 40 is arranged below the oscillating mirror 21 so as to reflect the transmitted light in the direction along the y-axis. The folding mirror 40 is a fixed mirror arranged as described above.

The transmitting/receiving unit 10, oscillating scanner 20, polygon scanner 30 and folding mirror 40 are arranged so that the transmitted light output from the light projecting unit 11 is reflected by the folding mirror 40, oscillating mirror 21 and polygon mirror 31 in that order and emitted within the scanning range, and the reflected light is reflected by the polygon mirror 31, oscillating mirror 21 and folding mirror 40 in that order and received by the light receiving unit 12. A more specific arrangement is described below using Figures 3 to 7.

4 to 6, the transmitting/receiving unit 10 is disposed to the left of the oscillating scanner 20. The light projecting unit 11 outputs a transmission light to the right along the x-axis.
The folding mirror 40 is disposed below the oscillating mirror 21 so that the direction of the transmitted light output from the light projector 11 is bent upward by approximately 90° by the folding mirror 40 and incident on the reflecting surface of the oscillating mirror 21 .

The polygon scanner 30 is disposed on the opposite side of the oscillating scanner 20 from the transmitting/receiving unit 10, i.e., to the right of the oscillating scanner 20. The polygon scanner 30 is disposed so that the transmission light arriving from the folding mirror 40 is deflected to the right by the oscillating mirror 21, enters the reflecting surface of the polygon mirror 31, and is reflected forward.

That is, the transmitting/receiving unit 10, the oscillating scanner 20, and the polygon scanner 30 are arranged side by side in the left-right direction of the lidar device 1. Meanwhile, as shown in FIG. 6 and FIG. 7, the transmitting/receiving unit 10 and the oscillating scanner 20 are arranged so as to overlap at least partially in the up-down direction. The oscillating scanner 20 and the polygon scanner 30 are also arranged so as to overlap at least partially in the up-down direction. Also, as shown in FIG. 5 and FIG. 7, the transmitting/receiving unit 10, the oscillating scanner 20, and the polygon scanner 30 are arranged so as to overlap at least partially in the front-rear direction. In this embodiment, the transmitting/receiving unit 10, the oscillating scanner 20, and the polygon scanner 30 are arranged so as to overlap most of them in the up-down direction and the front-rear direction. Also, the transmitting/receiving unit 10, the oscillating scanner 20, and the polygon scanner 30 are all configured so that the length in the front-rear direction is longer than the length in the up-down direction.

As shown in Fig. 5, the measurement unit 2 has a longer length in the left-right direction (i.e., width direction) than in the front-rear direction (i.e., depth direction). As shown in Fig. 6, the measurement unit 2 has a longer length in the left-right direction (i.e., width direction) than in the up-down direction (i.e., height direction). As shown in Fig. 7, the measurement unit 2 has a longer length in the front-rear direction (i.e., depth direction) than in the up-down direction (i.e., height direction). Note that the folding mirror 40 can be configured to be small enough so as not to affect the width, depth, and height directions of the measurement unit 2, so its description has been omitted above.
Since the size of the LIDAR device 1 depends on the size of the measurement unit 2, the length of the LIDAR device 1 increases in the following order: width direction > depth direction > height direction.

Next, the arrangement of the multiple transmission lights (referred to as light beams in this explanation) output from the light-projecting unit 11 and the detailed configuration of the light-projecting unit 11 will be described with reference to FIG. 4. The multiple light beams are output so as to be aligned along the direction of the rotation axis 321 of the polygon mirror 31 when they are incident on the reflecting surface of the polygon mirror 31. In this embodiment, the light source 111 is configured to output four light beams, and the four light beams are output so as to be aligned along the direction of the rotation axis 321 of the polygon mirror 31 when they are incident on the reflecting surface of the polygon mirror 31. Specifically, the light source 111 outputs four light beams aligned in the vertical direction.

The light source 111 and the lens 112 are configured so that the pupil plane is located between the oscillating mirror 21 and the polygon mirror 31 in the optical path of the light beam. The position of the pupil plane can be adjusted to a desired position by a general method of appropriately changing factors such as the positional relationship between the light source 111 and the lens 112, the curvature ratio and focal length of the lens 112, etc. At the pupil plane, the multiple light beams output from the light source 111 are most concentrated, and the width of each of the multiple light beams is smallest. In other words, at the pupil plane, the width of the multiple light beams as a whole is smallest.

Next, the detailed configuration of the oscillating scanner 20 will be described. The oscillating scanner 20 is configured so that the angular range in which the oscillating mirror 21 can oscillate is larger than the angular range in which the transmitted light is scanned by the oscillating mirror 21. In other words, the angular range in which the transmitted light is scanned by the oscillating mirror 21 is the actual scanning angular range in the lidar device 1 (specifically, the vertical scanning angular range). For example, the oscillating scanner 20 may be configured to oscillate the oscillating mirror 21 in an angular range larger than the actual scanning angular range, but to scan the transmitted light within the actual scanning angular range. Also, for example, the oscillating scanner 20 may be configured so that the oscillating mirror 21 can oscillate in an angular range larger than the actual scanning angular range, but to oscillate the oscillating mirror 21 within the actual scanning angular range during scanning.

[1-3. Control board layout]
As shown in Fig. 6 and Fig. 7, the control board 600 is disposed along a plane perpendicular to the rotation axis 321 of the polygon mirror 31. The plane perpendicular to the rotation axis 321 of the polygon mirror 31 is the xz plane, that is, a plane extending in the width direction and the depth direction of the lidar device 1. As described above, the length of the lidar device 1 increases in the order of width direction > depth direction > height direction. Therefore, in the lidar device 1, the plane extending in the width direction and the depth direction is the largest surface area compared to the plane extending in the width direction and the height direction and the plane extending in the depth direction and the height direction. The control board 600 is disposed along this largest surface area. The control board 600 is a rectangular board and disposed so that the long side is in the width direction and the short side is in the depth direction.

[1-4. Effects]
According to the first embodiment described above in detail, the following effects can be obtained.
(1a) The lidar device 1 includes one each of a light-projecting unit 11, a light-receiving unit 12, an oscillating scanner 20, and a polygon scanner 30, and the light-projecting unit 11, the light-receiving unit 12, the oscillating mirror 21, and the polygon mirror 31 are arranged so that transmitted light output from the light-projecting unit 11 is reflected by the oscillating mirror 21 and the polygon mirror 31 in that order and emitted within a scanning range, and the reflected light is reflected by the polygon mirror 31 and the oscillating mirror 21 in that order and received by the light-receiving unit 12. With this configuration, compared to a configuration including two or more of at least one of the light-projecting unit 11, the light-receiving unit 12, the oscillating scanner 20, and the polygon scanner 30, the size of the lidar device 1 as a whole can be reduced by the amount of the reduced components.

In addition, the scanning angle range of the oscillating scanner 20 is generally smaller than that of the polygon scanner 30. For this reason, as in this embodiment, the oscillating mirror 21 and the polygon mirror 31 are arranged so that the transmitted light is reflected in the order of the oscillating mirror 21 and the polygon mirror 31. In other words, by arranging the oscillating scanner 20, which has a smaller scanning angle range, before the polygon scanner 30, which has a larger scanning angle range, it is possible to configure the sizes of the oscillating mirror 21 and the polygon mirror 31 to be smaller than in a configuration in which the polygon scanner 30 is arranged before the oscillating scanner 20. Therefore, the size of the entire lidar device 1 can be reduced.

For example, as in the lidar device described in the prior art document, when light beams output simultaneously from two transmitters are deflected toward one polygon scanner by two oscillating scanners to perform scanning, it is necessary to adjust the optical axis for each of the two light beams, which requires high precision. In this embodiment, one light projector 11, one oscillating scanner 20, and one polygon scanner 30 are provided, so that optical axis adjustment can be made easier than when two transmitters and two oscillating scanners are provided for one polygon scanner as in the prior art document.

(1b) The control board 600 is arranged along a plane perpendicular to the rotation axis 321 of the polygon mirror 31, that is, a plane extending in the width direction and depth direction of the lidar device 1. As described above, the length of the lidar device 1 increases in the order of width direction > depth direction > height direction. Therefore, if the control board 600 is arranged in the lidar device 1 as in this embodiment, the area of the control board 600 can be designed to be larger than when the control board 600 is arranged along a plane extending in the width direction and height direction or a plane extending in the depth direction and height direction. Therefore, according to the configuration of this embodiment, when the control board 600 is arranged in the lidar device 1, the control board 600 can be arranged along the plane with the largest area among the planes of a rectangular parallelepiped consisting of the width direction, depth direction, and height direction, so that the space of the lidar device 1 can be used most efficiently and the area of the control board 600 can be maximized.

(1c) The polygon mirror 31 is configured to have five or fewer reflective surfaces. With this configuration, the area of each reflective surface can be increased without changing the radius of the circumscribing circle of the polygon mirror 31, compared to when the polygon mirror has six or more reflective surfaces. The increased area of each reflective surface increases the amount of reflected light reflected by each reflective surface and received by the light receiving unit 12. Therefore, the detection distance of the lidar device 1 can be increased without increasing the size of the polygon mirror 31, i.e., without increasing the size of the lidar device 1 as a whole.

Furthermore, when the polygon mirror 31 has five or fewer reflecting surfaces, the angle range in which the transmitted light can be scanned at each reflecting surface can be made larger than when the polygon mirror has six or more reflecting surfaces. For example, it is desirable for the polygon scanner to have a scanning angle range of 120°. When the polygon mirror has six reflecting surfaces, the angular range in which the transmitted light can be scanned at each reflecting surface is calculated to be 120°, but in reality, the angular range in which the transmitted light can be scanned is at most about 110°. On the other hand, when the polygon mirror has five reflecting surfaces, the angular range in which the transmitted light can be scanned at each reflecting surface is calculated to be 144°, which allows a scanning angle range of 120° with a margin. When the polygon mirror has four or fewer reflecting surfaces, the angular range in which the transmitted light can be scanned at each reflecting surface is larger.
Considering the operating cycle of the lidar device, it is more preferable that the polygon mirror have five reflective surfaces.

(1d) The oscillating scanner 20 is configured so that the angular range in which the oscillating mirror 21 can oscillate is larger than the angular range in which the transmitted light is scanned by the oscillating mirror 21. According to this configuration, since there is a margin in the angular range in which the oscillating mirror 21 can oscillate with respect to the actual scanning angle range, the actual scanning angle range can be adjusted within the angular range in which the oscillating mirror 21 can oscillate, as necessary. For example, the central position of the scanning angle range by the oscillating scanner 20 may deviate from the desired position due to the lidar device 1 being installed on the vehicle at an angle. In such a case, it was common to adjust the attitude of the lidar device so that the central position of the scanning angle range by the oscillating scanner becomes the desired position using an adjustment mechanism for adjusting the attitude of the lidar device provided on the bracket for mounting the lidar device to the vehicle. According to the configuration of this embodiment, when the central position of the scanning angle range by the oscillating scanner 20 deviates from the desired position, the deviation can be suppressed by adjusting the actual scanning angle range by the oscillating scanner 20 without using the above-mentioned adjustment mechanism. This eliminates the need for the adjustment mechanism, making it possible to reduce the overall size of the bracket, and also eliminates the process of adjusting the attitude of the rider device 1 using the adjustment mechanism.

In addition, since the scanning angle range of the oscillating scanner 20 can be adjusted, a different scanning angle range in the vertical direction of the lidar device 1 can be realized by changing the control of the oscillating scanner 20 with a common configuration of the lidar device 1. Specifically, the center position and the size of the scanning angle range of the oscillating scanner 20 can be adjusted according to the mounting position of the lidar device 1 on the vehicle and the purpose of use. In this way, by changing the control of the oscillating scanner 20, various scanning patterns can be easily realized without changing the design of the oscillating scanner 20 or the polygon scanner 30. In addition, the oscillation speed of the oscillating mirror 21 can also be adjusted. For example, if the purpose is to focus on the road surface, the control value of the oscillating motor 22 can be rewritten so that the center position of the scanning angle range of the oscillating scanner 20 is lower than the horizontal direction and the oscillation speed of the oscillating mirror 21 is slowed down, thereby scanning the road surface with high accuracy.

(1e) The transmission/reception unit 10 is disposed to the left of the oscillating scanner 20, and the light projector 11 is configured to output transmission light in a direction along the x-axis. The folding mirror 40 is disposed below the oscillating mirror 21 so as to reflect the transmission light output from the light projector 11 in a direction along the y-axis. The polygon scanner 30 is disposed on the opposite side of the oscillating scanner 20 from the transmission/reception unit 10. With this configuration, the transmission/reception unit 10, the oscillating scanner 20, and the polygon scanner 30 are disposed side by side in the width direction of the lidar device 1, making it possible to reduce the height and depth of the lidar device 1. The configuration of this embodiment is suitable for cases where it is desired to reduce the height and depth of the lidar device 1, such as when the lidar device 1 is mounted on the grille or inside the vehicle cabin.

(1f) The transmitting/receiving unit 10 and the oscillating scanner 20 are arranged so that they at least partially overlap in the vertical direction. With this configuration, the vertical length of the lidar device 1, i.e., the height direction, can be further reduced compared to a case in which the transmitting/receiving unit 10 and the oscillating scanner 20 are arranged so that they do not overlap in the vertical direction.

(1g) The light projecting unit 11 is configured to output a plurality of light beams, and the plurality of light beams are arranged and output so as to be aligned along the direction of the rotation axis 321 of the polygon mirror 31 when they are incident on the reflecting surface of the polygon mirror 31. With this configuration, scanning in the vertical direction can be performed with a plurality of light beams, so the number of rotations of the polygon mirror 31 required to scan the entire scanning range can be reduced compared to a configuration in which scanning is performed with a single light beam. For this reason, when the rotation speed of the polygon mirror 31 is the same, the operation cycle of the lidar device 1 can be shortened compared to a configuration in which scanning is performed with a single light beam. Note that even when scanning is performed with a single light beam, it is possible to shorten the operation cycle by increasing the rotation speed of the polygon mirror, but when the rotation speed of the polygon mirror increases, the time required for the reflected light to be reflected by the polygon mirror becomes shorter. Therefore, the amount of reflected light reflected by the polygon mirror decreases, and the amount of reflected light received by the light receiving unit also decreases, so the detection distance of the lidar device becomes shorter. Considering that the lidar device is mounted on a vehicle, it is required that the operation cycle is short and the detection distance is long. By using multiple light beams to scan in the vertical direction as in the configuration of this embodiment, it is possible to shorten the operating cycle of the lidar device 1 while simultaneously reducing the rotation speed of the polygon mirror 31 to increase the detection distance of the lidar device 1.

(1h) The light source 111 and the lens 112 are configured so that the pupil plane is located between the oscillating mirror 21 and the polygon mirror 31 in the optical path of the light beam. As described above, the width of the multiple light beams as a whole is smallest at the pupil plane, so with this configuration, the reflective surfaces of both the oscillating mirror 21 and the polygon mirror 31 can be configured to be small compared to when the pupil plane is not at that position. For example, if the pupil plane is located close to the oscillating scanner 20, the reflective surface of the oscillating mirror 21 can be configured to be particularly small. Also, for example, if the pupil plane is located close to the polygon mirror 31, the reflective surface of the polygon mirror 31 can be configured to be particularly small.

In the first embodiment, the light-projecting unit 11 corresponds to a transmitting unit, the light-receiving unit 12 corresponds to a receiving unit, the LIDAR device 1 corresponds to a distance measuring device, the transmitted wave corresponds to the transmitted light, and the reflected wave corresponds to the reflected light.
[2. Second embodiment]
[2-1. Differences from the first embodiment]
The second embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

In the lidar device 1 of the first embodiment described above, the control unit 3 is configured to use the measurement unit 2 to measure the distance and relative speed of the object that reflected the transmitted light. In contrast, the lidar device 1A of the second embodiment differs from the first embodiment in that the control unit 3A is configured to execute the error correction process shown in FIG. 10 in addition to measuring the distance and relative speed. That is, like the control unit 3 of the first embodiment, the control unit 3A controls the drive of the oscillating motor 22 based on a control value when measuring the distance and relative speed using the measurement unit 2, but in the second embodiment, the control value is corrected by the error correction process.

As shown in FIG. 8, the lidar device 1A further includes a storage unit 4.
The storage unit 4 stores error information representing the error between a preset reference shape and the actual shape for each of the multiple reflecting surfaces of the polygon mirror 31. The error between the reference shape and the actual shape for each of the multiple reflecting surfaces of the polygon mirror 31 is measured during the manufacturing stage of the lidar device 1, and the error information is stored in the storage unit 4 during the manufacturing stage. In this embodiment, the polygon mirror 31 has five reflecting surfaces, so the error from the reference shape for each of the five surfaces is measured, and the error information for the five surfaces is stored in the storage unit 4. If the error from the reference shape of a reflecting surface is within a predetermined tolerance range, no error information may be stored for that reflecting surface, or error information indicating that there is no error may be stored.

The error information includes information that represents the error of the multiple reflecting surfaces of the polygon mirror 31 being tilted with respect to a preset reference position. FIG. 9A shows the reference position of the reflecting surface of the polygon mirror 31. In this embodiment, the reference position is a position where the reflecting surface is parallel to the rotation axis 321. FIG. 9B shows a case where the reflecting surface of the polygon mirror 31 is tilted downward with respect to the reference position, and FIG. 9C shows a case where the reflecting surface of the polygon mirror 31 is tilted upward with respect to the reference position. Note that FIG. 9 shows only one of the multiple reflecting surfaces of the polygon mirror 31, and the tilt of the reflecting surface is emphasized to explain the tilt with respect to the reference position. The error information includes information that represents the error of the downward tilt with respect to the reference position as in (b) and the error of the upward tilt with respect to the reference position as in (c).

The error caused by the inclination of the multiple reflecting surfaces of the polygon mirror 31 with respect to the reference position includes an error caused by the inclination of the multiple reflecting surfaces themselves and an error caused by a misalignment of the rotation axis 321 of the polygon mirror 31. The error caused by the inclination of the multiple reflecting surfaces themselves is an error caused by the reflecting surfaces of the polygon mirror 31 being manufactured with an inclination with respect to the reference position. The error caused by a misalignment of the rotation axis 321 of the polygon mirror 31 is an error caused by the rotation axis 321 being rotated while wobbling when the polygon mirror 31 is mounted on the rotary motor 32 and rotated around the rotation axis 321. When the polygon mirror 31 rotates with the rotation axis 321 wobbling, the reflecting surfaces of the polygon mirror 31 are tilted upward or downward with respect to the reference position, which causes the above error.

Furthermore, the error information includes information indicating that the multiple reflective surfaces of the polygon mirror 31 are convex or concave with respect to a reference shape. (a) in FIG. 9 shows the reference shape of the reflective surface of the polygon mirror 31. The reference shape of the reflective surface is flat. (d) in FIG. 9 shows a case where the reflective surface of the polygon mirror 31 is convex with respect to the reference shape, and (e) in FIG. 9 shows a case where the reflective surface of the polygon mirror 31 is concave with respect to the reference shape. Note that in FIG. 9, the concaves and convexes of the reflective surface are emphasized to illustrate that the reflective surface is convex or concave with respect to the reference shape. The error information includes information indicating an error that is convex with respect to the reference shape, such as (d), and an error that is concave with respect to the reference shape, such as (e).

[2-2. Processing]
The error correction process executed by the control unit 3A will be described with reference to the flowchart of Fig. 10. Note that the error correction process is executed when, for example, an ignition switch of the vehicle is turned on.

First, in S101, the control unit 3A acquires error information from the storage unit 4. Note that S101 corresponds to a process performed by the error information acquisition unit.
Next, in S102, the control unit 3A corrects the control value of the oscillating motor 22 so as to cancel out errors occurring in vertical scanning due to errors between the reference shapes and actual shapes of the multiple reflecting surfaces of the polygon mirror 31. Specifically, the control unit 3A corrects the control value of the oscillating motor 22 so as to change at least one of the center position of the scanning angle range by the oscillating scanner 20 and the size of the scanning angle range by the oscillating scanner 20, according to error information for each of the multiple reflecting surfaces of the polygon mirror 31. A more specific correction method will be described below with reference to FIG.

In FIG. 9, the three arrows pointing to the reflecting surface of the polygon mirror 31 indicate the transmitted light scanned by the oscillating scanner 20 that passes through the center and both ends of the scanning angle range, and the dotted line indicates the center of the scanning angle range by the oscillating scanner 20. Note that (b) to (e) of FIG. 9 show the transmitted light when the oscillating motor 22 is driven based on the corrected control value.

9(b) and (c), the control unit 3A corrects the control value of the oscillating motor 22 so as to change the center position of the scanning angle range by the oscillating scanner 20. When the reflective surface is tilted downward with respect to the reference position as shown in (b), the control unit 3A changes the center position of the scanning angle range by the oscillating scanner 20 so that the center position of the scanning angle range by the oscillating scanner 20 is more upward. When the reflective surface is tilted upward with respect to the reference position as shown in (c), the control unit 3A changes the center position of the scanning angle range by the oscillating scanner 20 so that the center position of the scanning angle range by the oscillating scanner 20 is more downward. The error information may include information on the degree of tilt indicating the degree to which the reflective surface is tilted downward or upward with respect to the reference position, and the control unit 3A may adjust the degree to which the center position of the scanning angle range is changed upward or downward according to the information on the degree of tilt.

In addition, when the error information indicates that the multiple reflecting surfaces are convex or concave with respect to the reference shape, as shown in (d) and (e) of FIG. 9, the control unit 3A corrects the control value of the oscillating motor 22 so as to change the size of the scanning angle range by the oscillating scanner 20. As shown in (d), when the reflecting surface is convex with respect to the reference shape, the control unit 3A changes the size of the scanning angle range by the oscillating scanner 20 so as to narrow the scanning angle range. For example, the control unit 3A may correct the control value of the oscillating motor 22 so as to slow down the oscillation speed of the oscillating mirror 21. As shown in (e), when the reflecting surface is concave with respect to the reference shape, the control unit 3A changes the size of the scanning angle range by the oscillating scanner 20 so as to widen the scanning angle range. For example, the control unit 3A may correct the control value of the oscillating motor 22 so as to speed up the oscillation speed of the oscillating mirror 21. The error information may also include degree information indicating the degree to which the reflecting surface is convex or concave with respect to the reference shape, and the control unit 3A may adjust the degree to which the size of the scanning angle range is changed (for example, the degree to which the oscillation speed of the oscillating mirror 21 is changed) according to the degree information.

The control value of the oscillating motor 22 is corrected for each reflecting surface according to the error information of that reflecting surface. The control value of the oscillating motor 22 can be set to a different value for each reflecting surface of the polygon mirror 31, and the control unit 3A can control the oscillating motor 22 differently for each reflecting surface based on the control value for each reflecting surface of the polygon mirror 31.

If there is no error information for a certain reflecting surface, or if the error information indicates that there is no error, correction of the control value of the oscillating motor 22 for that reflecting surface does not need to be performed.

After correcting the control value of the rocking motor 22 in accordance with the error information in S102, the control unit 3A ends the error correction process in Fig. 10. Note that S102 corresponds to the process performed by the error correction unit.
The control unit 3A controls the driving of the oscillating motor 22 based on the control value corrected by the error correction process when performing scanning using the measurement unit 2. Note that the control of the driving of the oscillating motor 22 based on the control value in the control unit 3A corresponds to processing as a drive control unit.

[2-3. Effects]
According to the second embodiment described above in detail, the same effect as that of the first embodiment can be obtained. In addition, according to the second embodiment, by correcting the control value of the oscillating motor 22, it is possible to adjust the transmitted light to scan a preset vertical scanning range regardless of the processing accuracy of the polygon mirror 31. In recent years, there has been a demand for highly accurate vertical scanning in the lidar device 1A, but it is difficult to manufacture the polygon mirror 31 with the required level of accuracy. In this regard, according to the second embodiment, the influence of errors caused in the manufacture of the polygon mirror 31 on the accuracy of the vertical scanning can be offset by correcting the control value of the oscillating motor 22, so that the accuracy required for the manufacture of the polygon mirror 31 can be relaxed.

[3. Third embodiment]
[3-1. Differences from the first embodiment]
The third embodiment has a basic configuration similar to that of the first embodiment, and therefore differences will be described below. Note that the same reference numerals as those in the first embodiment indicate the same configurations, and the preceding description will be referred to.

In the lidar device 1 of the first embodiment described above, the control unit 3 is configured to use the measurement unit 2 to measure the distance and relative speed to an object that reflects the transmitted light. In contrast, in the lidar device 1B of the third embodiment, the control unit 3B differs from the first embodiment in that it is configured to execute the gradient correction process shown in FIG. 12 in addition to measuring the distance and relative speed. That is, like the control unit 3 of the first embodiment, when measuring the distance and relative speed using the measurement unit 2, the control unit 3B controls the drive of the oscillating motor 22 based on a control value, but in the third embodiment, the control value is corrected by the gradient correction process.

As shown in FIG. 11, the vehicle on which the lidar device 1B is mounted is equipped with an acceleration sensor 5. The acceleration sensor 5 is a sensor that detects the acceleration acting on the vehicle. The acceleration sensor 5 detects the inclination of the vehicle in the forward/rearward direction.

[3-2. Processing]
The gradient correction process executed by the control unit 3B will be described with reference to the flowchart of Fig. 12. Note that the gradient correction process is executed at a predetermined cycle while the ignition switch of the vehicle is turned on.

First, in S201, the control unit 3B acquires gradient information that indicates the gradient of the road on which the vehicle (i.e., the host vehicle) on which the lidar device 1B is mounted is traveling. In this embodiment, the gradient information includes information indicating whether the gradient of the road on which the host vehicle is traveling is an upward gradient, a downward gradient, or no gradient. Specifically, the control unit 3B acquires gradient information by acquiring information on the longitudinal tilt of the host vehicle from the acceleration sensor 5, and based on this, determining whether the gradient of the road on which the host vehicle is traveling is an upward gradient, a downward gradient, or no gradient. Note that S201 corresponds to the processing performed by the gradient acquisition unit.

Next, in S202, the control unit 3B corrects the control value of the oscillating motor 22 so as to change the center position of the scanning angle range by the oscillating scanner 20 according to the gradient information. Specifically, if the gradient of the road on which the vehicle is traveling is an upward gradient, the control unit 3B changes the center position of the scanning angle range by the oscillating scanner 20 so that the center position of the scanning angle range is more upward. Also, if the gradient of the road on which the vehicle is traveling is a downward gradient, the control unit 3B changes the center position of the scanning angle range by the oscillating scanner 20 so that the center position of the scanning angle range is more downward. If the gradient of the road on which the vehicle is traveling is flat, the control unit 3B does not change the center position of the scanning angle range by the oscillating scanner 20. Note that the gradient information may include gradient degree information indicating the degree of road gradient, and the control unit 3B may adjust the degree to which the center position of the scanning angle range is changed upward or downward according to the gradient degree information.

After correcting the control value of the rocking motor 22 in accordance with the gradient information in S202, the control unit 3B ends the gradient correction process in Fig. 12. Note that S202 corresponds to the process performed by the gradient correction unit.
The control unit 3B controls the driving of the oscillating motor 22 based on the control value corrected by the gradient correction process when performing scanning using the measurement unit 2. Note that the control of the driving of the oscillating motor 22 based on the control value in the control unit 3B corresponds to processing as a drive control unit.

[3-3. Effects]
According to the third embodiment described above in detail, the same effects as those of the first embodiment can be obtained. In addition, according to the third embodiment, the vertical scanning range of the lidar device 1B can be adjusted to an appropriate direction according to the road gradient while the vehicle equipped with the lidar device 1B is traveling. For example, when the road on which the vehicle is traveling is a downhill road, the vertical scanning range of the lidar device 1B can be adjusted further downward to make it easier to detect an object ahead.

4. Other embodiments
Although the embodiments of the present disclosure have been described above, it goes without saying that the present disclosure is not limited to the above-described embodiments and can take various forms.

(4a) In the above embodiment, the control board 600 is arranged along a plane perpendicular to the rotation axis 321 of the polygon mirror 31, that is, a plane extending in the width direction and depth direction of the lidar device 1. However, the arrangement of the control board 600 is not limited to this. For example, the control board 600 may be arranged along a plane perpendicular to the oscillation axis 221 of the oscillating mirror 21, that is, a plane extending in the width direction and height direction of the lidar device 1. With this configuration, the area of the control board 600 is smaller than that of the arrangement of the above embodiment, but the area of the control board 600 can be designed to be relatively large by arranging the control board 600 along a plane including the width direction that is the longest among the width direction, depth direction, and height direction of the lidar device 1. For example, with this configuration, the area of the control board 600 can be designed to be large compared to the case where the control board 600 is arranged along a plane extending in the depth direction and height direction.

(4b) In the above embodiment, the polygon mirror 31 is configured to have five or fewer reflective surfaces. However, the number of reflective surfaces is not limited to five or fewer. For example, the polygon mirror may have six reflective surfaces.

(4c) In the above embodiment, the polygon mirror 31 is configured so that all of the multiple reflecting surfaces are parallel to the rotation axis 321 of the polygon mirror 31. However, the shape of the multiple reflecting surfaces of the polygon mirror is not limited to this. For example, the polygon mirror may be configured so that the inclination angles of each of the multiple reflecting surfaces with respect to the rotation axis are all the same. That is, the multiple reflecting surfaces may have a uniform, predetermined inclination angle. With this configuration, by designing the inclination angle of the reflecting surfaces of the polygon mirror to a predetermined angle, the center position of the scanning angle range of the oscillating scanner can be changed to a desired direction without changing the scanning angle range of the oscillating scanner. Also, for example, the polygon mirror may be configured so that all of the inclination angles of each of the multiple reflecting surfaces with respect to the rotation axis are different. For example, the multiple reflecting surfaces may be configured to have different inclination angles that increase by a predetermined angle. With this configuration, the scanning angle range in the vertical direction can be made wider than when all of the multiple reflecting surfaces are parallel to the rotation axis 321 of the polygon mirror 31 or when the multiple reflecting surfaces have a uniform inclination angle.

(4d) In the above embodiment, the oscillating scanner 20 is configured so that the angular range in which the oscillating mirror 21 can oscillate is greater than the angular range in which the transmitted light is scanned by the oscillating mirror 21. However, the angular range in which the oscillating scanner can oscillate is not limited to this. For example, the angular range in which the oscillating scanner can oscillate may be configured to be the same as the angular range in which the transmitted light is scanned by the oscillating mirror.

(4e) In the above embodiment, the transmitting/receiving unit 10 is disposed to the left of the oscillating scanner 20, the polygon scanner 30 is disposed to the right of the oscillating scanner 20, and the folding mirror 40 is disposed below the oscillating mirror 21. However, the arrangement of the transmitting/receiving unit 10, the oscillating scanner 20, the polygon scanner 30, and the folding mirror 40 is not limited to this. For example, the transmitting/receiving unit 10 may be disposed to the right of the oscillating scanner 20, and the polygon scanner 30 may be disposed to the left of the oscillating scanner 20. In addition, for example, the folding mirror 40 may be disposed above the oscillating mirror 21 so as to reflect the transmitted light in a direction along the y-axis. That is, the transmitted light is output from the light projecting unit 11 so as to pass above the oscillating mirror 21, and the folding mirror 40 may be disposed above the oscillating mirror 21 so that the transmitted light is bent downward by approximately 90° by the folding mirror 40 and is incident on the reflecting surface of the oscillating mirror 21.

In addition, the transmission/reception unit 10 may be arranged behind the oscillating scanner 20, the folding mirror 40 may be arranged below or above the oscillating mirror 21, and the polygon scanner 30 may be arranged to the left or right of the oscillating scanner 20. As an example of such an arrangement, FIG. 13 shows an example in which the transmission/reception unit 10 is arranged behind the oscillating scanner 20, the folding mirror 40 is arranged below the oscillating mirror 21, and the polygon scanner 30 is arranged to the right of the oscillating scanner 20. In such an arrangement, the light projecting unit 11 outputs the transmission light in a direction along the z-axis, and the folding mirror 40 reflects the transmission light output from the light projecting unit 11 in a direction along the y-axis. Specifically, the folding mirror 40 is arranged below or above the oscillating mirror 21 so that the direction of travel of the transmission light output from the light projecting unit 11 is bent by the folding mirror 40 approximately 90° upward or downward and is incident on the reflection surface of the oscillating mirror 21. The transmitting/receiving unit 10 and the oscillating scanner 20 may be arranged so that they at least partially overlap in the vertical direction. This configuration makes it possible to reduce the width and height of the lidar device. This configuration is suitable for cases where it is desired to reduce the width and height of the lidar device, such as when the lidar device is mounted on the rooftop of a vehicle.

The transmitting/receiving unit 10 may be disposed below or above the oscillating scanner 20, and the polygon scanner 30 may be disposed to the left or right of the oscillating scanner 20. As an example of such an arrangement, FIG. 14 shows an example in which the transmitting/receiving unit 10 is disposed below the oscillating scanner 20, and the polygon scanner 30 is disposed to the right of the oscillating scanner 20. In such an arrangement, the light projecting unit 11 outputs transmission light in a direction along the y-axis, and the transmission light output from the light projecting unit 11 is directly incident on the reflecting surface of the oscillating mirror 21. With this configuration, it is possible to reduce the width and depth of the lidar device. This configuration is suitable for cases in which it is desired to reduce the width and depth of the lidar device, such as when the lidar device is mounted on the side of the vehicle.

(4f) In the above embodiment, the light-projecting unit 11 is configured to output multiple light beams, but the configuration of the light-projecting unit 11 is not limited to this. For example, the light-projecting unit 11 may be configured to output one light beam.

(4g) In the above embodiment, the pupil plane is configured to be located between the oscillating mirror 21 and the polygon mirror 31 in the optical path of the light beam. However, the position of the pupil plane is not limited to this. For example, the pupil plane may be configured to be located between the light projector 11 and the folding mirror 40, between the polygon mirror 31 and the optical window 200, etc. in the optical path of the light beam.

(4h) In the above embodiment, the lidar device 1 is used as an example of a distance measuring device, but the type of distance measuring device is not limited to this. For example, the distance measuring device may be a millimeter wave radar device.

(4i) As shown in FIG. 15, the lidar device 1C may be configured such that a communication section 110 is formed in the housing 100 to communicate the internal space housing the measurement section 2 with the outside, and a breathing filter 800 is provided in the communication section 110. Note that FIG. 15 is a schematic diagram of the lidar device 1C viewed from the optical window 200 side with the optical window 200 removed, so the measurement section 2 housed in the internal space of the housing 100 is illustrated. The breathing filter 800 is attached to the housing 100 so as to block the communication section 110, and is configured to allow ventilation between the internal space and the outside through the communication section 110 while suppressing liquid from entering the internal space of the housing 100. Examples of liquids that may be used include rainwater, water used for car washing, water scooped up by the vehicle while it is traveling, solutions resulting from the melting of calcium chloride used as a snow-melting agent, and organic solvents such as brake oil. Note that the breathing filter 800 is also called a vent filter. This configuration allows the pressure applied to the internal space of the housing 100 to escape to the outside while preventing the intrusion of liquid from the outside, thereby reducing the stress on each component housed in the internal space of the housing 100. In addition, air can be circulated between the internal space of the housing 100 and the outside, improving the cooling efficiency of the electronic components in the lidar device 1.

(4j) In the second embodiment, the control unit 3A is configured to perform error correction processing, and in the third embodiment, the control unit 3B is configured to perform gradient correction processing, but the control unit may be configured to perform both error correction processing and gradient correction processing.

(4k) In the third embodiment, the control unit 3B is configured to obtain information on the longitudinal tilt of the vehicle from the acceleration sensor 5, and obtain gradient information based on the information. However, the method in which the control unit obtains the gradient information is not limited to this. For example, the control unit may obtain the gradient information by obtaining the current position of the vehicle and map data including information on the road gradient from the in-vehicle device, and reading information on the road gradient at the current position of the vehicle from the map data. The vehicle on which the lidar device is mounted may include, as the in-vehicle device, a position detection device that detects the current position of the vehicle based on a GPS signal received via a GPS antenna, and a map database that stores map data including information on the road gradient.

(4l) The function of one component in the above embodiments may be distributed among multiple components, or the functions of multiple components may be integrated into one component. In addition, part of the configuration of the above embodiments may be omitted. In addition, at least part of the configuration of the above embodiments may be added to or substituted for the configuration of another of the above embodiments.

(4m) In addition to the above-mentioned lidar devices 1, 1A, 1B, and 1C, the present disclosure can be realized in various forms, such as the control units 3A and 3B that constitute the lidar devices 1A and 1B, a system that includes the control units 3A and 3B as components, a program for causing a computer to function as the control units 3A and 3B, a medium on which this program is recorded, and an error correction method and a gradient correction method for the lidar devices 1A and 1B.

1, 1A, 1B, 1C... Lidar device, 2... Measurement unit, 11... Light projecting unit, 12... Light receiving unit, 20... Oscillating scanner, 21... Oscillating mirror, 22... Oscillating motor, 30... Polygon scanner, 31... Polygon mirror, 32... Rotating motor, 221... Oscillating shaft, 321... Rotating shaft.

Claims (16)

A measurement unit (2) is provided for irradiating a transmission wave and detecting a reflected wave from an object irradiated with the transmission wave,
The measurement unit includes:
A transmitting unit (11) configured to output the transmission wave;
A receiver (12) configured to detect the reflected wave;
an oscillating scanner (20) including an oscillating mirror (21) that reflects the transmission wave and the reflected wave, and an oscillating motor (22) configured to oscillate the oscillating mirror about an oscillating axis (221) that extends in a first direction;
a polygon scanner (30) including: a polygon mirror (31) having a plurality of reflecting surfaces that reflect the transmitted wave and the reflected wave; and a rotary motor (32) configured to rotate the polygon mirror about a rotation axis (321) that extends in a second direction perpendicular to the first direction;
Each of the
the transmitting unit, the receiving unit, the oscillating mirror, and the polygon mirror are arranged such that the transmission wave output from the transmitting unit is reflected by the oscillating mirror and the polygon mirror in this order and emitted within a preset scanning range, and the reflected wave is reflected by the polygon mirror and the oscillating mirror in this order and received by the receiving unit,
A drive control unit (3, 3A, 3B) configured to control the drive of the swing motor based on a control value;
an error information acquisition unit (3A, S101) configured to acquire error information representing an error between a preset reference shape and an actual shape for each of the plurality of reflecting surfaces of the polygon mirror;
an error correction unit (3A, S102) configured to correct the control value so that an error occurring in the scanning in the second direction due to the error of the plurality of reflecting surfaces is offset;
Further comprising:
the error correction unit corrects the control value so as to change at least one of a center position of a scanning angle range by the oscillating scanner and a size of a scanning angle range by the oscillating scanner in accordance with the error information of each of the plurality of reflecting surfaces;
A distance measuring device, wherein the error information includes information representing an error in tilt of the multiple reflecting surfaces relative to a predetermined reference position, and the error in tilt of the multiple reflecting surfaces relative to the reference position includes an error caused by the tilt of the multiple reflecting surfaces themselves and an error caused by a misalignment of the rotation axis of the polygon mirror. 2. A distance measuring device according to claim 1,
The distance measuring device is a lidar device that outputs a light beam as the transmission wave. 3. A distance measuring device according to claim 2,
The transmitting unit includes a light source (111) that outputs the light beam and a lens (112).
A distance measuring device, wherein the light source and the lens are configured so that a pupil plane is located between the oscillating mirror and the polygon mirror in the optical path of the light beam. A distance measuring device, comprising:
A measurement unit (2) is provided for irradiating a transmission wave and detecting a reflected wave from an object irradiated with the transmission wave,
The measurement unit includes:
A transmitting unit (11) configured to output the transmission wave;
A receiver (12) configured to detect the reflected wave;
an oscillating scanner (20) including an oscillating mirror (21) that reflects the transmission wave and the reflected wave, and an oscillating motor (22) configured to oscillate the oscillating mirror about an oscillating axis (221) that extends in a first direction;
a polygon scanner (30) including: a polygon mirror (31) having a plurality of reflecting surfaces that reflect the transmitted wave and the reflected wave; and a rotary motor (32) configured to rotate the polygon mirror about a rotation axis (321) that extends in a second direction perpendicular to the first direction;
Each of the
the transmitting unit, the receiving unit, the oscillating mirror, and the polygon mirror are arranged such that the transmission wave output from the transmitting unit is reflected by the oscillating mirror and the polygon mirror in this order and emitted within a preset scanning range, and the reflected wave is reflected by the polygon mirror and the oscillating mirror in this order and received by the receiving unit,
the distance measuring device is a lidar device that outputs a light beam as the transmission wave,
The transmitting unit includes a light source (111) that outputs the light beam and a lens (112).
A distance measuring device, wherein the light source and the lens are configured so that a pupil plane is located between the oscillating mirror and the polygon mirror in the optical path of the light beam. A distance measuring device according to any one of claims 2 to 4,
the transmitting unit is configured to output a plurality of the light beams as the transmission wave,
A distance measuring device, wherein the plurality of light beams are outputted so as to be aligned along the direction of the rotation axis of the polygon mirror when they are incident on a reflecting surface of the polygon mirror. A distance measuring device according to any one of claims 1 to 5,
The device further includes a plate-shaped control board (600) having an electronic control circuit on which electronic components are mounted,
A distance measuring device, wherein the control board is disposed along a plane perpendicular to the rotation axis of the polygon mirror or a plane perpendicular to the oscillation axis of the oscillating mirror. A distance measuring device according to any one of claims 1 to 6,
The measurement unit further includes a folding mirror (40) that is disposed on paths of the transmission wave and the reflected wave so as to reflect the transmission wave output from the transmission unit in the direction of the oscillating mirror and to reflect the reflected wave reflected by the oscillating mirror in the direction of the reception unit,
A distance measuring device in which the transmitting unit, the receiving unit, the folding mirror, the oscillating mirror and the polygon mirror are arranged so that the transmission wave output from the transmitting unit is reflected by the folding mirror, the oscillating mirror and the polygon mirror in that order and emitted within the scanning range, and the reflected wave is reflected by the polygon mirror, the oscillating mirror and the folding mirror in that order and received by the receiving unit. 8. A distance measuring device according to claim 7,
The transmitting section and the receiving section are configured as one transmitting/receiving unit (10),
In a three-dimensional orthogonal coordinate system, the positive x-axis direction is to the right, the negative x-axis direction is to the left, the positive y-axis direction is up, the negative y-axis direction is down, the positive z-axis direction is forward, and the negative z-axis direction is backward, with the first direction being along the z-axis and the second direction being along the y-axis, and the distance measuring device being installed so that the transmission wave reflected by the polygon mirror is emitted forward,
The transmitting/receiving unit is disposed to the left of the oscillating scanner or to the right of the oscillating scanner, and the transmitting unit is configured to output the transmission wave in a direction along the x-axis,
the reflecting mirror is disposed below or above the oscillating mirror so as to reflect the transmission wave in a direction along the y-axis,
A distance measuring device, wherein the polygon scanner is disposed on the opposite side of the oscillating scanner from the transmitting/receiving unit. 8. A distance measuring device according to claim 7,
The transmitting unit and the receiving unit are configured as one transmitting/receiving unit,
In a three-dimensional orthogonal coordinate system, the positive x-axis direction is to the right, the negative x-axis direction is to the left, the positive y-axis direction is up, the negative y-axis direction is down, the positive z-axis direction is forward, and the negative z-axis direction is backward, with the first direction being along the z-axis and the second direction being along the y-axis, and the distance measuring device being installed so that the transmission wave reflected by the polygon mirror is emitted forward,
The transmitting and receiving unit is disposed behind the oscillating scanner, and the transmitting section is configured to output the transmission wave in a direction along the z-axis;
the reflecting mirror is disposed below or above the oscillating mirror so as to reflect the transmission wave in a direction along the y-axis,
A distance measuring device, wherein the polygon scanner is disposed to the left or right of the oscillating scanner. 10. A distance measuring device according to claim 8 or claim 9,
A distance measuring device, wherein the transmitting/receiving unit and the oscillating scanner are arranged so as to at least partially overlap in the vertical direction. A distance measuring device according to any one of claims 1 to 6,
The transmitting unit and the receiving unit are configured as one transmitting/receiving unit,
In a three-dimensional orthogonal coordinate system, the positive x-axis direction is to the right, the negative x-axis direction is to the left, the positive y-axis direction is up, the negative y-axis direction is down, the positive z-axis direction is forward, and the negative z-axis direction is backward, with the first direction being along the z-axis and the second direction being along the y-axis, and the distance measuring device being installed so that the transmission wave reflected by the polygon mirror is emitted forward,
The transmitting and receiving unit is disposed below or above the oscillating scanner, and the transmitting unit is configured to output the transmission wave in a direction along the y-axis;
A distance measuring device, wherein the polygon scanner is disposed to the left or right of the oscillating scanner. A distance measuring device according to any one of claims 1 to 11 ,
A distance measuring device, wherein the number of the reflecting surfaces of the polygon mirror is five or less. A distance measuring device according to any one of claims 1 to 12 ,
A distance measuring device in which the polygon mirror has a plurality of reflective surfaces all parallel to the rotation axis, a plurality of reflective surfaces all having the same inclination angle with respect to the rotation axis, or a plurality of reflective surfaces all having different inclination angles with respect to the rotation axis. A distance measuring device according to any one of claims 1 to 13 ,
A distance measuring device, wherein the oscillating scanner is configured so that an angular range in which the oscillating mirror can oscillate is greater than an angular range in which the transmission wave is scanned by the oscillating mirror. A distance measuring device according to any one of claims 1 to 14 ,
A drive control unit (3, 3A, 3B) configured to control the drive of the swing motor based on a control value;
A gradient acquisition unit (3B, S201) configured to acquire gradient information representing a gradient of a road on which a vehicle equipped with the distance measuring device is traveling;
a gradient correction unit (3B, S202) configured to correct the control value so as to change a center position of a scanning angle range by the oscillating scanner according to the gradient information;
The distance measuring device further comprises: A distance measuring device according to any one of claims 1 to 15 ,
A housing (100) having an internal space for accommodating the measuring unit and in which a communication part (110) for communicating the internal space with the outside is formed;
A breathing filter (800) provided in the communication portion;
The distance measuring device further comprises:

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