JP6447400B2 - Laser radar apparatus and control method thereof - Google Patents

Description

  The present invention relates to a laser radar device that scans a pulse laser beam and detects an object using the scanned pulse laser beam.

  A laser radar apparatus including a scanning device has an advantage that a measurement range can be widened because an object is detected using laser light scanned by the scanning device. This laser radar device is currently applied in various fields. For example, it is mounted on an aircraft or helicopter for terrain survey, mounted on a vehicle such as an automobile for driving support, or for crime prevention. It is attached under the eaves.

  As the laser radar device, Patent Document 1 discloses a technique for measuring the azimuth and distance of a detected object using pulsed laser light deflected by a rotating deflection unit.

Japanese Patent No. 5251638 (paragraphs 0029 to 0035)

  In the laser radar device, if the amount of laser light is increased, the measurable distance becomes longer, so that the object detection capability is improved. As a laser device that can increase the amount of laser light, there is a multi-stack laser. The multi-stack laser has a structure in which a plurality of laser diode bars that respectively emit pulsed laser beams are stacked. Since the laser light emitted from the multi-stack laser is composed of a plurality of pulsed laser lights arranged at a predetermined pitch in the direction in which the plurality of laser diode bars are stacked, the amount of laser light can be increased.

  However, in the multi-stack laser, the light amount distribution of the laser light is not constant, and the beam mode is a multi-mode. This is because the laser light emitted from the multi-stack laser is composed of a plurality of pulse laser lights arranged in one direction at a predetermined pitch, and the amount of light between the adjacent pulse laser lights is smaller than that of the pulse laser light. It is.

  When the object irradiated with the laser beam scanned by the scanning device has a size that fits between adjacent pulsed laser beams (for example, an electric wire), and when the object is positioned between adjacent pulsed laser beams Therefore, there is a possibility that the amount of reflected light reflected from the object is different and cannot be detected accurately. Further, in the worst case, there is a possibility that the object cannot be detected when the object is located between the adjacent pulse laser beams.

  As the above countermeasures, a method of shortening a cycle of emitting laser light (in other words, a cycle of emitting a plurality of pulsed laser beams at the same time) or reducing a scanning speed of the laser beam can be considered. However, if the period of emitting the laser beam is shortened, the energy required for laser oscillation cannot be increased, and the amount of laser beam is reduced. Moreover, if the scanning speed of the laser beam is lowered, the measurement range in the main scanning direction becomes narrow or the measurement time becomes long.

  The present invention improves the ability to detect an object having a size smaller than that between adjacent pulse laser beams when detecting an object using a laser beam composed of a plurality of pulse laser beams arranged in one direction at a predetermined pitch. It is an object of the present invention to provide a laser radar device that can be operated and a method for controlling the laser radar device.

  A laser radar device according to the present invention that achieves the above-described object is configured to emit a laser beam composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch, and to periodically emit the laser beam. In addition, an emission control unit for controlling the laser unit, a scanning unit for scanning the laser beam periodically emitted by the laser unit along the one direction, and the laser beam scanned by the scanning unit are irradiated. A light receiving unit that receives the reflected light reflected by the irradiated region, and the emission control unit further includes a portion corresponding to the interval between the adjacent pulse laser beams in the laser beam before switching the timing. The timing at which the laser unit emits the laser beam is switched so that the pulse laser beam in the laser beam after the timing is switched is positioned.

  The emission control unit switches the timing at which the laser unit emits the laser light during a period in which the laser unit is controlled to periodically emit the laser light. The switching is performed so that the pulsed laser light in the laser light after switching the timing is positioned at a position corresponding to the interval between the adjacent pulsed laser lights in the laser light before switching the laser light emission timing. Thereby, in the irradiation region irradiated with the scanned laser beam, the position where the adjacent pulse laser beam is positioned can be prevented from being fixed. Therefore, according to the laser radar device of the present invention, when detecting an object using a laser beam composed of a plurality of pulse laser beams arranged in one direction at a predetermined pitch, it is smaller than between adjacent pulse laser beams. The ability to detect size objects can be improved.

  In the above configuration, the scanning unit includes a mirror unit having a plurality of mirror surfaces that scan the laser beam in the main scanning direction, which is the one direction, and a motor that rotates the mirror unit, and the mirror unit includes: By rotating, the mirror surface that scans the laser light is sequentially switched, and a plurality of the irradiation regions by the laser light scanned by each of the plurality of mirror surfaces are aligned in the sub-scanning direction, The plurality of mirror surfaces have different inclinations.

  This configuration is an example of a scanning unit. According to this configuration, the reflected light reflected from the plurality of irradiation regions arranged in the sub-scanning direction becomes an image of one frame.

  In the above configuration, the laser beam is shifted in the one direction by a half of the predetermined pitch with respect to the laser beam emitted at the first timing and the first timing. There is a second timing, and the emission control unit switches from the first timing to the second timing, or switches from the second timing to the first timing.

  This configuration is an example of control that enables the pulsed laser light in the laser light after switching the timing to be located at a position corresponding to the interval between the adjacent pulsed laser beams in the laser light before switching the timing of emitting the laser light. It is.

  In the above configuration, when the reflected light reflected from the plurality of irradiation areas arranged in the sub-scanning direction is used as an image of one frame, the emission control unit changes from the first timing to the second timing. And switching from the second timing to the first timing are repeated alternately each time the frame is switched.

  This configuration is a first mode of control for switching timing. In the first aspect, the location where the adjacent pulse laser beams are located in the irradiation region can be changed every time the frame is switched. Accordingly, even if an object having a size smaller than between adjacent pulse laser beams is included between adjacent pulse laser beams in a certain frame, it can be prevented from falling between adjacent pulse laser beams in the next frame. Therefore, according to the first aspect, an object having a size smaller than between adjacent pulse laser beams can be detected in any one of two consecutive frames regardless of the size in the sub-scanning direction.

  In the above configuration, the emission control unit scans the laser light for switching from the first timing to the second timing and switching from the second timing to the first timing. Repeatedly every time the mirror surface is switched.

  This configuration is a second mode of control for switching timing. In the second aspect, since the timing of emitting the laser light is switched every time the mirror surface that scans the laser light is switched, it is possible to prevent the adjacent pulse laser lights from being connected in the sub-scanning direction in one frame. Therefore, according to the second aspect, an object having a size smaller than that between adjacent pulse laser beams and elongated in the sub scanning direction (for example, an electric wire extending in the sub scanning direction) is detected in all frames. be able to.

  In the above configuration, when the reflected light reflected from the plurality of irradiation regions arranged in the sub-scanning direction is an image of one frame, the emission control unit first applies to the laser unit each time the frame is switched. The first timing and the second timing are alternately selected as the timing at which the laser beam is emitted.

  This configuration is a third mode of control for switching timing. Similarly to the second aspect, the third aspect switches the timing of emitting the laser light every time the mirror surface that scans the laser light is switched.

  As a second aspect, the number of mirror surfaces is, for example, 4, and in all frames, the first mirror surface scans the laser beam emitted at the first timing, and the second mirror surface is The laser beam emitted at the second timing is scanned, the third mirror surface is scanned with the laser beam emitted at the first timing, and the fourth mirror surface is emitted at the second timing. Consider an example of scanning with laser light. In this example, in the irradiation region irradiated with the laser beam scanned by the first mirror surface, a position where the adjacent pulse laser beams are located is fixed. The same applies to the second to fourth mirror surfaces. Therefore, in this example, there is a possibility that a short object cannot be detected along the sub-scanning direction, with a size smaller than between adjacent pulse laser beams.

  In the third aspect, every time the frame is switched, the first timing and the second timing are alternately selected as the timing at which the laser unit first emits the laser beam. In one of the two consecutive frames, the first mirror surface scans the laser beam emitted at the first timing, and the second mirror surface scans the laser beam emitted at the second timing. Scanning means that the third mirror surface scans the laser beam emitted at the first timing, and the fourth mirror surface scans the laser beam emitted at the second timing.

  In the other of the two consecutive frames, the first mirror surface scans the laser beam emitted at the second timing, and the second mirror surface scans the laser beam emitted at the first timing. Scanning means that the third mirror surface scans the laser beam emitted at the second timing, and the fourth mirror surface scans the laser beam emitted at the first timing.

  According to the 3rd aspect, in the irradiation area | region irradiated with the laser beam scanned by the 1st mirror surface, the location in which adjacent pulse laser light is located can be changed whenever a flame | frame switches. The same applies to the second to fourth mirror surfaces. Therefore, according to the third aspect, it is possible to improve the ability to detect a short object having a size smaller than that between adjacent pulse laser beams and along the sub-scanning direction.

  In the above configuration, the laser unit emits the plurality of pulse laser beams each having an elongated shape when viewed from the front of the plurality of pulse laser beams, and the laser radar device further includes the plurality of pulse laser beams. Each includes an optical system that is incident on the mirror surface in a state having the elongated shape along the sub-scanning direction.

  According to this configuration, since the laser having an elongated shape in the sub scanning direction is irradiated, the range of the irradiation region in the sub scanning direction can be widened.

  The method for controlling a laser radar device according to the present invention includes an emission control step for periodically emitting laser light composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch, and the emission control step. A scanning step of scanning the laser light periodically emitted in step 1 along the one direction, and a light receiving step of receiving reflected light reflected by an irradiation region irradiated with the laser light scanned in the scanning step. The emission control step further includes positioning the pulsed laser light in the laser light after switching the timing at a position corresponding to between the adjacent pulsed laser light in the laser light before switching the timing. Thus, the timing for emitting the laser beam is switched.

The control method of the laser radar device according to the present invention has the same effects as the laser radar device according to the present invention.
In one embodiment of the laser radar device according to the present invention, a laser unit configured to emit a laser beam composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch, and the laser beam is periodically emitted. An emission control unit for controlling the laser unit, a scanning unit for scanning the laser beam periodically emitted by the laser unit along the one direction, and the laser beam scanned by the scanning unit are irradiated. A light receiving unit that receives the reflected light reflected by the irradiation region, and the emission control unit further sets the timing at a position corresponding to the interval between the adjacent pulsed laser beams in the laser beam before switching the timing. The timing at which the laser unit emits the laser beam is switched so that the pulsed laser beam in the laser beam after switching is positioned. A mirror unit having a plurality of mirror surfaces for scanning the laser beam in the main scanning direction, and a motor for rotating the mirror unit, and scanning the laser beam by rotating the mirror unit The mirror surfaces are switched in order, and the plurality of mirror surfaces have different inclinations so that the plurality of irradiation regions by the laser light scanned by the plurality of mirror surfaces are aligned in the sub-scanning direction. The timing includes a first timing and the laser beam emitted in one direction by a half of the predetermined pitch with respect to the laser beam emitted at the first timing. The emission control unit switches from the first timing to the second timing, or from the second timing to the first timing. The emission control unit scans the laser light for switching from the first timing to the second timing and switching from the second timing to the first timing. Repeatedly every time the mirror surface is switched .
One form of the control method of the laser radar apparatus according to the present invention includes an emission control step for performing control to periodically emit laser light composed of a plurality of pulsed laser lights arranged in one direction at a predetermined pitch, and scanning. A scanning step of scanning the laser beam periodically emitted in the emission control step along the one direction using a scanning unit, and a reflection in an irradiation area irradiated with the laser beam scanned in the scanning step. A light receiving step for receiving the reflected light, and the emission control step further includes a step after switching the timing to a position corresponding to between adjacent laser pulses in the laser light before switching the timing. The timing for emitting the laser beam is switched so that the pulsed laser beam in the laser beam is positioned, and the scanning unit A mirror unit having a plurality of mirror surfaces for scanning the laser beam in the main scanning direction, and a motor for rotating the mirror unit, and scanning the laser beam by rotating the mirror unit The mirror surfaces are switched in order, and the plurality of mirror surfaces have different inclinations so that the plurality of irradiation regions by the laser light scanned by the plurality of mirror surfaces are aligned in the sub-scanning direction. The timing includes a first timing and the laser beam emitted in one direction by a half of the predetermined pitch with respect to the laser beam emitted at the first timing. And the emission control step switches from the first timing to the second timing, or from the second timing to the second timing. The emission control step scans the laser light for switching from the first timing to the second timing and switching from the second timing to the first timing. Repeatedly every time the mirror surface is switched.

  According to the present invention, when detecting an object using a laser beam composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch, the ability to detect an object having a size smaller than between adjacent pulsed laser beams. Can be improved.

It is a block diagram which shows the structure of the laser radar apparatus which concerns on this embodiment. It is the schematic diagram which looked at the laser part from the front of the advancing direction of a laser beam. It is explanatory drawing explaining the four mirror surfaces which a polygon mirror has. It is explanatory drawing explaining the irradiation area | region irradiated by the laser beam which the polygon mirror rotated 1 time and was scanned. It is a perspective view which shows the external appearance of the laser radar apparatus which concerns on this embodiment. It is explanatory drawing explaining a mode that the laser beam from a laser radar apparatus is irradiating the measurement area | region (irradiation area | region). It is a graph which shows the relationship between a laser beam and irradiation light quantity. It is explanatory drawing explaining the relationship between the pulse laser beam which comprises the laser beam radiate | emitted at the 1st timing, and the pulse laser beam which comprises the laser beam radiate | emitted at the 2nd timing. It is explanatory drawing explaining the irradiation area | region by a 1st aspect. It is explanatory drawing explaining the irradiation area | region by a 2nd aspect. It is explanatory drawing explaining the irradiation area | region by a 3rd aspect.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each figure, the structure which attached | subjected the same code | symbol shows that it is the same structure, The description is abbreviate | omitted about the content which has already demonstrated the structure.

  FIG. 1 is a block diagram showing a configuration of a laser radar device 1 according to the present embodiment. The laser radar device 1 includes a laser unit 2, a controller 3, a collimator lens 4, a scanning unit 5, a motor controller 6, a light receiving lens 7, and a light receiving unit 8.

  FIG. 2 is a schematic view of the laser unit 2 viewed from the front in the traveling direction of the laser light L. The laser unit 2 has a structure in which three laser diode bars 20a, 20b, and 20c are stacked. When the laser diode bars 20a, 20b, and 20c are not distinguished, they are referred to as laser diode bars 20. The direction in which the three laser diode bars 20 are stacked is the main scanning direction D1 which is one direction. The number of laser diode bars 20 is not limited to three as long as it is plural.

  Each of the laser diode bars 20a, 20b, and 20c is a semiconductor, and includes light emitting units 21a, 21b, and 21c that emit pulsed laser beams PLa, PLb, and PLc. When the pulse laser beams PLa, PLb, and PLc are not distinguished from each other, they are described as pulse laser beams PL. When the light emitting units 21a, 21b, and 21c are not distinguished, they are referred to as the light emitting unit 21.

  The laser unit 2 emits a laser beam L composed of pulsed laser beams PLa, PLb, and PLc simultaneously emitted by the light emitting units 21a, 21b, and 21c. That is, the laser unit 2 emits a laser beam L composed of a plurality of pulsed laser beams PL arranged in one direction at a predetermined pitch. By configuring the laser beam L with a plurality of pulse laser beams PL, the light amount of the laser beam L is increased.

  The light emitting unit 21 has an elongated shape along the sub-scanning direction D2 orthogonal to the main scanning direction D1. This is because the light emitting unit 21 is configured by a plurality of light emitting layers (not shown) arranged linearly in the sub-scanning direction D2. Therefore, when the pulse laser beam PL is viewed from the front, the pulse laser beam PL has an elongated shape along the sub-scanning direction D2.

  The laser unit 2 is not limited to a multi-stack laser and may be a plurality of laser elements arranged in one direction at a predetermined pitch. Further, the shape of the pulse laser beam PL viewed from the front is not limited to an elongated shape.

  Referring to FIG. 1, the controller 3 controls the entire operation of the laser radar device 1 and includes a CPU, a RAM, a ROM, an LD driver, and the like. The LD driver is a driver circuit that drives the laser unit 2. The controller 3 includes an emission control unit 30 as a functional block.

  The emission control unit 30 periodically repeats the control for causing the light emitting unit 21 to emit the pulsed laser light PL simultaneously (for example, 16.7 μs). Thereby, the emission control unit 30 performs control to cause the laser unit 2 to periodically emit the laser light L.

  In the laser radar device 1, each of the three pulsed laser beams PL constituting the laser beam L is incident on the mirror surface F (FIG. 3) of the scanning unit 5 in a state of having an elongated shape along the sub-scanning direction D2. An optical system (not shown). The collimating lens is one of the optical systems, and collimates the laser light L periodically emitted from the laser unit 2.

  The scanning unit 5 is an optical device that scans the laser light L collimated by the collimating lens along the main scanning direction D1. In the present embodiment, a polygon mirror 50 and a motor 51 that rotates the polygon mirror 50 will be described as an example of the scanning unit 5. The scanning part 5 is not limited to this, A galvanometer mirror, a MEMS mirror, etc. can also be used.

  The motor controller 6 controls the motor 51 and controls the rotation of the polygon mirror 50 according to a command from the controller 3.

  The polygon mirror 50 is an example of a mirror unit. The polygon mirror 50 has a plurality of side surfaces, and each side surface becomes a mirror surface. In the present embodiment, a polygon mirror 50 having four side surfaces, that is, four mirror surfaces will be described as an example.

  FIG. 3 is an explanatory diagram for explaining the four mirror surfaces F1, F2, F3, and F4 of the polygon mirror 50. FIG. When the mirror surfaces F1, F2, F3, and F4 are not distinguished, they are referred to as mirror surfaces F. Each of the four mirror surfaces F scans the laser light L in the main scanning direction D1.

  Along the rotational direction of the polygon mirror 50, the mirror surface F2 is located next to the mirror surface F1, the mirror surface F3 is located next to the mirror surface F2, and the mirror surface F4 is located next to the mirror surface F3. The mirror surface F1 is located next to the surface F4. As the polygon mirror 50 rotates, the mirror surface F that scans the laser light L is switched in order.

  FIG. 4 is an explanatory diagram for explaining an irradiation region R irradiated with the scanned laser light L after the polygon mirror 50 has been rotated once. This corresponds to one frame. The irradiation region R includes an irradiation region r1, an irradiation region r2, an irradiation region r3, and an irradiation region r4 that are arranged in order in the sub-scanning direction D2. When the irradiation region r1 is not distinguished, it is described as the irradiation region r.

  The relationship of the inclination θ1 of the mirror surface F1 <the inclination θ2 of the mirror surface F2 <the inclination θ3 of the mirror surface F3 <the inclination θ4 of the mirror surface F4 is established. For this reason, the irradiation region r1 irradiated with the laser beam L scanned on the mirror surface F1, the irradiation region r2 irradiated with the laser beam L scanned on the mirror surface F2, and the laser beam L scanned on the mirror surface F3 are irradiated. The irradiation region r3 to be irradiated and the irradiation region r4 to be irradiated with the laser light L scanned by the mirror surface F4 are not overlapped but are aligned in the sub-scanning direction D2.

  Referring to FIGS. 1 and 4, the reflected light reflected by the irradiation region r enters the polygon mirror 50 (mirror surface F), is reflected by the polygon mirror 50 (mirror surface F), and is received by the light receiving lens 7. Is done. The reflected light received by the light receiving lens 7 is received by the light receiving unit 8. The light receiving unit 8 includes a light amount sensor such as a photodiode. The reflected light of the irradiation region R constituted by the irradiation regions r1, r2, r3, r4 arranged in the sub-scanning direction D2 becomes an image of one frame.

  FIG. 5 is a perspective view showing an appearance of the laser radar device 1 according to the present embodiment. The laser radar device 1 includes a housing 9 that houses the laser unit 2, the controller 3, the collimator lens 4, the scanning unit 5, the motor controller 6, the light receiving lens 7, and the light receiving unit 8 shown in FIG. The housing 9 includes a bottomed semicylindrical lower member 90 and a lidded semiconical upper member 91 connected to the upper portion of the lower member 90. A side surface of the upper member 91 having an obliquely curved surface is opened, and a window 92 is provided in the opening.

  The laser beam L scanned by the polygon mirror 50 passes through the window portion 92 and is emitted toward the measurement region. FIG. 6 is an explanatory diagram illustrating a state in which the laser beam L from the laser radar device 1 is irradiating the measurement region (irradiation region R). The reflected light reflected by the irradiation region R passes through the window portion 92 and is received by the light receiving portion 8 via the polygon mirror 50 and the light receiving lens 7.

  FIG. 7 is a graph showing the relationship between the laser light L and the amount of irradiation light. The vertical axis of the graph indicates the amount of irradiation light. The horizontal axis of the graph indicates the positions of the pulse laser beams PLa, PLb, and PLc. As described above, the laser beam L is composed of the pulse laser beams PLa, PLb, and PLc. Between the pulse laser light PLa and the pulse laser light PLb and between the pulse laser light PLb and the pulse laser light PLc are defined as B between adjacent pulse laser lights. The amount of light between the adjacent pulse laser beams B is smaller than that of the pulse laser PL.

  For example, at a point 20 m from the laser unit 2, the pitch P between the pulse laser beam PLa and the pulse laser beam PLb and the pitch P between the pulse laser beam PLb and the pulse laser beam PLc are 17 mm. This corresponds to a width corresponding to 2.5 electric wires, and is a size in which one electric wire can be accommodated between adjacent pulse laser beams B. Since the amount of light is small between the pulse laser beams B, the wires may not be detected when the wires are positioned between the adjacent pulse laser beams B.

  Therefore, the emission control unit 30 switches the timing at which the laser unit 2 emits the laser light L during the control for causing the laser unit 2 to periodically emit the laser light L. More specifically, the timing at which the emission control unit 30 causes the laser unit 2 to emit the laser light L includes a first timing and a second timing. The second timing is a timing at which the laser beam L emitted at the first timing is shifted in the main scanning direction D1 by a half of a predetermined pitch P. For example, when the laser beam L is emitted from the laser unit 2 at a period of 16.7 μsec, the emission control unit 30 delays the second timing by 3.34 μsec from the first timing.

  FIG. 8 shows the pulse laser beams PLa, PLb, and PLc that constitute the laser beam L emitted at the first timing, and the pulse laser beams PLa, PLb, and PLc that constitute the laser beam L emitted at the second timing. It is explanatory drawing explaining the relationship. The pulse laser beam PL of the laser beam L emitted at the second timing is located at a position corresponding to the interval B between adjacent pulse laser beams of the laser beam L emitted at the first timing.

  When the timing is switched from the first timing to the second timing, the pulse laser beam PL of the laser beam L after switching the timing to a position corresponding to the interval B between adjacent pulse laser beams of the laser beam L before switching the timing. Is located. The same applies when switching from the second timing to the first timing.

  As described above, the emission control unit 30 causes the pulsed laser light PL of the laser light L after switching the timing to be located at a position corresponding to the interval between the adjacent pulsed laser beams B of the laser light L before switching the timing. The timing for emitting the laser beam L is switched.

  By this switching control, it is possible to prevent the portion where the adjacent pulse laser beam B is located in the irradiation region r (FIG. 4) irradiated with the scanned laser beam L from being fixed. Therefore, according to the laser radar device 1 according to the present embodiment, when an object is detected using the laser light L configured by the plurality of pulsed laser lights PL arranged in one direction at a predetermined pitch P, adjacent pulses are detected. The ability to detect an object having a size smaller than the distance between laser beams B can be improved.

  In addition, according to the laser radar device 1 according to the present embodiment, the emission control unit 30 determines the timing at which the laser unit 2 emits the laser light L during the control for causing the laser unit 2 to periodically emit the laser light L. Since switching is performed, the resolution of the laser radar device 1 can be improved.

  There are three modes for switching the timing at which the laser unit 2 emits the laser light L. In the first aspect, the timing at which the laser beam L is emitted is switched every time the polygon mirror 50 makes one rotation. This is to switch the timing of emitting the laser beam L every time the frame is switched. FIG. 9 is an explanatory diagram for explaining the irradiation region R according to the first aspect. In the irradiation region R, the portions irradiated with the pulse laser beams PLa, PLb, and PLc are indicated by hatching, and the portions between the adjacent pulse laser beams B are indicated by white.

  As described above, the emission control unit 30 controls the laser unit 2 to periodically emit the laser beam L composed of the pulsed laser beams PLa, PLb, and PLc. The emission control unit 30 switches from the first timing to the second timing and from the second timing to the first timing every time the polygon mirror 50 rotates once (that is, every time the frame is switched). And are repeated alternately.

  The upper side of FIG. 9 shows the irradiation region R by the laser light L emitted at the first timing, and the lower side shows the irradiation region R by the laser light L emitted at the second timing. Yes. The irradiation region R shown on the upper side of FIG. 9 and the irradiation region R shown on the lower side of FIG. 9 are alternately formed every time the polygon mirror 50 makes one rotation.

  The laser beam L emitted at the second timing (in other words, at a position corresponding to the interval between the adjacent pulsed laser beams B in the laser beam L emitted at the first timing (in other words, the laser beam L before timing switching). For example, the pulsed laser beam PL in the laser beam L) after timing switching is located. Therefore, in a certain frame, even if an object is located between adjacent pulse laser beams B, the pulse laser beam PL is irradiated in the next frame.

  In the first mode, in the irradiation region R, the location where the adjacent pulse laser beam B is located can be changed every time the frame is switched. Accordingly, even if an object having a size smaller than that between the adjacent pulse laser beams B is included in the adjacent pulse laser beam B in a certain frame, it cannot be included in the adjacent pulse laser beam B in the next frame. . Therefore, according to the first aspect, an object having a size smaller than that between the adjacent pulse laser beams B can be detected in one of the two consecutive frames regardless of the size of the sub-scanning direction D2.

  In the second mode, the timing at which the laser beam L is emitted is switched each time the mirror surface F (FIG. 3) for scanning the laser beam L is switched. FIG. 10 is an explanatory diagram for explaining the irradiation region R according to the second mode. The emission control unit 30 alternates switching from the first timing to the second timing and switching from the second timing to the first timing each time the mirror surface F that scans the laser light L is switched. repeat.

  The irradiation regions r1 and r3 are irradiation regions with the laser light L emitted at the first timing. The irradiation regions r2 and r4 are irradiation regions with the laser light L emitted at the second timing. An irradiation region R shown in FIG. 10 is formed every time the polygon mirror 50 rotates once.

  The pulse laser beam PL in the laser beam L emitted at the second timing is located at a position corresponding to the interval B between adjacent pulse laser beams in the laser beam L emitted at the first timing.

  In the second mode, every time the mirror surface F that scans the laser beam L is switched, the timing of emitting the laser beam L is switched, and therefore, between adjacent pulsed laser beams B is connected in the sub-scanning direction D2 in one frame. Can be prevented. Therefore, according to the second aspect, all the frames of an elongated object (for example, an electric wire extending in the sub-scanning direction D2) having a size smaller than that between the adjacent pulse laser beams B and extending along the sub-scanning direction D2 are all frames. Can be detected.

  In the second mode, as described with reference to FIG. 10, in all frames, the mirror surface F1 scans the laser light L emitted at the first timing, and the mirror surface F2 emits at the second timing. The mirror surface F3 scans the laser beam L emitted at the first timing, and the mirror surface F4 scans the laser beam L emitted at the second timing. In the second mode, in the irradiation region r1 irradiated with the laser beam L scanned on the mirror surface F1, the position where the adjacent pulse laser beam B is located is fixed. The same applies to the mirror surfaces F2 to F4. Therefore, in the second mode, there is a possibility that a short object having a size smaller than that between the adjacent pulse laser beams B and a short object along the sub-scanning direction D2 cannot be detected.

  The third aspect can solve the problem. Similarly to the second aspect, the third aspect switches the timing of emitting the laser light L every time the mirror surface F that scans the laser light L is switched.

  FIG. 11 is an explanatory diagram for explaining the irradiation region R according to the third aspect. The emission control unit 30 alternately selects the first timing and the second timing as the timing at which the laser unit 2 first emits the laser light L every time the frame is switched. In other words, the emission control unit 30 reverses the order of the first timing and the second timing each time the frame is switched. In one of two consecutive frames, the mirror surface F1 scans the laser light L emitted at the first timing, and the mirror surface F2 scans the laser light L emitted at the second timing. The mirror surface F3 scans the laser light L emitted at the first timing, and the mirror surface F4 scans the laser light L emitted at the second timing. Thereby, the irradiation region R shown in the upper side of FIG. 11 is formed.

  In the other of the two consecutive frames, the mirror surface F1 scans the laser light L emitted at the second timing, and the mirror surface F2 scans the laser light L emitted at the first timing, The surface F3 scans the laser light L emitted at the second timing, and the mirror surface F4 scans the laser light L emitted at the first timing. Thereby, the irradiation region R shown in the lower side of FIG. 11 is formed.

  According to the 3rd aspect, in the irradiation area | region r1 irradiated with the laser beam L scanned by the mirror surface F1, the location where B between adjacent pulse laser beams is located can be changed whenever a flame | frame switches. . The same applies to the mirror surfaces F2, F3, and F4. Therefore, according to the third aspect, it is possible to improve the ability to detect a short object having a size smaller than that between adjacent pulse laser beams B and along the sub-scanning direction D2.

  According to the first aspect, the second aspect, and the third aspect, each of the three pulsed laser beams PL shown in FIG. 2 has an elongated shape along the sub-scanning direction D2, and the mirror surface F (FIG. 3). Therefore, the range of the irradiation region R in the sub-scanning direction D2 can be widened.

DESCRIPTION OF SYMBOLS 1 Laser radar apparatus 2 Laser part 5 Scanning part 8 Light receiving part 30 Output control part 50 Polygon mirror 51 Motor D1 Main scanning direction D2 Sub scanning direction PL, PLa, PLb, PLc Pulsed laser light L Laser light F, F1, F2, F3 , F4 Mirror surface P Pitch of pulsed laser beam B Between adjacent pulsed laser beams R Irradiation region r, r1 to r4 Irradiation region

Claims (6)

A laser unit that emits a laser beam composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch; and
An emission control unit for controlling the laser unit so as to periodically emit the laser beam;
A scanning unit that scans the laser beam periodically emitted by the laser unit along the one direction;
A light receiving unit that receives reflected light reflected by an irradiation region irradiated with the laser beam scanned by the scanning unit, and
The emission control unit is further configured so that the pulse laser light in the laser light after switching the timing is located at a position corresponding to between the adjacent pulse laser lights in the laser light before switching the timing. Switching the timing at which the laser unit emits the laser light,
The scanning unit includes a mirror unit having a plurality of mirror surfaces that scan the laser light in the main scanning direction that is the one direction, and a motor that rotates the mirror unit, and by rotating the mirror unit , And sequentially switching the mirror surface for scanning the laser beam,
The plurality of mirror surfaces have different inclinations so that the plurality of irradiation regions by the laser beams scanned by the plurality of mirror surfaces are aligned in the sub-scanning direction,
The timing includes a first timing and a second timing at which the laser beam is shifted in one direction by a half of the predetermined pitch with respect to the laser beam emitted at the first timing. And
The emission control unit switches from the first timing to the second timing, or switches from the second timing to the first timing,
The emission control unit switches the mirror surface that scans the laser light between switching from the first timing to the second timing and switching from the second timing to the first timing. A laser radar device that alternates every time.   When the reflected light reflected from the plurality of irradiation areas arranged in the sub-scanning direction is an image of one frame, the emission control unit first causes the laser light to be applied to the laser unit each time the frame is switched. 2. The laser radar device according to claim 1, wherein the first timing and the second timing are alternately selected as the timing at which light is emitted. The laser unit emits the plurality of pulse laser beams each having an elongated shape when viewed from the front of the plurality of pulse laser beams,
3. The laser radar device according to claim 1, further comprising an optical system in which each of the plurality of pulsed laser beams is incident on the mirror surface in a state of having the elongated shape along the sub-scanning direction. The laser radar device described. An emission control step for performing control to periodically emit a laser beam composed of a plurality of pulsed laser beams arranged in one direction at a predetermined pitch;
A scanning step of scanning the laser beam periodically emitted in the emission control step along the one direction using a scanning unit;
A light receiving step for receiving the reflected light reflected by the irradiation region irradiated with the laser light scanned in the scanning step, and
In the emission control step, the pulse laser light in the laser light after switching the timing is positioned at a position corresponding to between the adjacent pulse laser lights in the laser light before switching the timing. Switch the timing to emit laser light,
The scanning unit includes a mirror unit having a plurality of mirror surfaces that scan the laser light in the main scanning direction that is the one direction, and a motor that rotates the mirror unit, and by rotating the mirror unit , And sequentially switching the mirror surface for scanning the laser beam,
The plurality of mirror surfaces have different inclinations so that the plurality of irradiation regions by the laser beams scanned by the plurality of mirror surfaces are aligned in the sub-scanning direction,
The timing includes a first timing and a second timing at which the laser beam is shifted in one direction by a half of the predetermined pitch with respect to the laser beam emitted at the first timing. And
The emission control step switches from the first timing to the second timing, or switches from the second timing to the first timing,
In the emission control step, the mirror surface that scans the laser light is switched between switching from the first timing to the second timing and switching from the second timing to the first timing. A method for controlling a laser radar apparatus, which is alternately repeated every time. In the emission control step, when the reflected light reflected from the plurality of irradiation areas arranged in the sub-scanning direction is an image of one frame, the laser unit emits the laser light every time the frame is switched. The method of controlling a laser radar device according to claim 4, wherein the first timing and the second timing are alternately selected as the timing at which the laser beam is first emitted. Each of the plurality of pulse laser beams has an elongated shape when viewed from the front of the plurality of pulse laser beams,
6. The laser radar device according to claim 4, further comprising an optical system in which each of the plurality of pulsed laser beams is incident on the mirror surface in a state of having the elongated shape along the sub-scanning direction. A method for controlling the laser radar device according to the description.

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