JP2019074447A - Laser radar device - Google Patents

Abstract

To provide a laser radar device which exhibits satisfactory performance, though it is compact and inexpensive.SOLUTION: A laser radar device 1 comprises: a deflector 3 for oscillating an oscillatory reflection surface 5 around a first rotation axis 6 and thereby deflecting within a first angle range α and while so doing, reflecting light from a light source 2; and an element assembly 4 for expanding the angle range of deflection of light from the deflector 3 to a second angle range larger than the first angle range α. The element assembly 4 includes a plurality of reflection units A to F, N to S, each reflecting a part of light beams in deflection directions from the deflector 3, and a plurality of refraction units G to M, each refracting light beams in deflection directions other than the part of light beams in deflection directions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser radar device provided with a deflection device that deflects coherent light from a light source.

  In recent years, with the growing momentum for the realization of smart mobility, there has been a growing interest in autonomous driving technology in particular. In order to realize automatic driving, it is necessary to instantly grasp the surrounding traffic environment accurately. For this reason, development of a laser radar device capable of scanning the surrounding 360 ° has been activated.

  As such a laser radar device, for example, Patent Document 1 discloses a laser radar device capable of three-dimensionally recognizing an object around the device. In this device, a light receiving sensor in which a plurality of light receiving element sections are two-dimensionally arranged is configured to receive the reflected light guided by the reflecting section in the light receiving area.

  Then, a convex mirror is disposed in a light projection path of the laser beam from the laser diode to the outside space, and the laser beam from the deflection unit toward the outside space is expanded. The laser beam is deflected by a deflection unit rotated by a motor and irradiated to the external space. The incident position of the reflected light in the light receiving area is determined in accordance with the direction of incidence when the reflected light from the external space is incident on the deflection unit.

  On the other hand, there is known a device for scanning an object to be measured with a laser beam by deflecting the laser beam using a MEMS (Micro-Electro-Mechanical Systems) mirror (see, for example, Patent Document 3). As one of such devices, Patent Document 2 discloses a laser scanning device that covers a wide range using a plurality of light sources.

  This device comprises a laser light source, a light scanning unit for scanning laser light emitted from the laser light source, and light for detecting the reflected light returned from the object to be measured by the laser light scanned by the light scanning unit. And a detection unit. Laser light emitted from the laser light source is incident on the light scanning unit from a plurality of directions.

JP, 2013-072770, A JP, 2015-025901, A JP, 2013-007779, A

  Objects to which the laser radar device is to be mounted are mobile bodies such as passenger cars for improving mobility. Therefore, the laser radar device is required to be simple in structure, resistant to vibration and vibration, small in size and low in cost.

  However, according to the laser radar device of Patent Document 1, a motor is used to turn the deflection unit, which is disadvantageous in terms of both weight and cost. Furthermore, since a curved mirror is used for the deflection unit, if the curvature is not set accurately, the beam shape when the laser light is irradiated may be distorted, and accurate scanning may become impossible.

  Further, according to the laser scanning device of Patent Document 2, since a plurality of expensive laser light sources are used, the device cost is increased. In addition, since the back surface of the MEMS mirror also needs to be a mirror surface, the manufacturing process may be increased and the manufacturing cost may be increased.

  An object of the present invention is to provide a laser radar device having good performance while being compact and low in cost.

The laser radar device according to the first invention is
A light source that outputs light having coherence;
A light from the light source is provided, having a peristaltic reflection surface that reflects the light from the light source, and deflecting the reflected light within a first angle range by swinging the peristaltic reflection surface around the first rotation axis. A deflector that reflects
And deflection range expansion means for expanding an angular range of deflection of light from the deflection device to a second angular range larger than the first angular range,
The deflection range extending means is
A plurality of reflecting portions for reflecting light in one of the plurality of deflection directions from the deflection device in the respective reflection directions;
It is characterized by comprising: a plurality of refracting portions for refracting light of deflection directions other than the part among the light of the plurality of deflection directions from the deflection device in respective refracting directions.

  According to the first aspect of the invention, the light from the light source is deflected by the deflection device within the first angle range, and is further outputted by being deflected by the deflection range extending means at the larger second angle range. And a deflection | deviation range expansion means is comprised by several reflection part and several refraction | bending part.

  As a result, the laser radar device capable of scanning a large angle range with sufficient accuracy can be compact and inexpensive without using power such as a motor that increases weight and a curved mirror or the like that complicates optical design. Can be provided by

  In the laser radar device according to a second aspect of the present invention, in the first aspect, the deflection range extending means is composed of an element assembly including the plurality of reflecting portions and the plurality of refracting portions arranged in a line. .

  According to the second aspect of the invention, since the deflection expanding means can be made compact, miniaturization of the laser radar device can be achieved more reliably.

According to a third aspect of the present invention, there is provided a laser radar device according to the second aspect of the present invention.
The plurality of refracting portions are arrayed on the side of the array center of the element assembly, and the plurality of reflecting portions are arrayed on both sides of the array.
Each of the refracting portions and the reflecting portions is characterized in that the angle formed by the vector of the corresponding incident light from the deflecting device and the vector of the emitted light is smaller as it is closer to the center of the array.

  According to the third aspect of the invention, the deflection direction of the light emitted from the element assembly can be changed not continuously but continuously as in the case where the deflection direction of the light from the deflection device changes.

  A laser radar device according to a fourth aspect of the present invention is the laser radar device according to any one of the first to third aspects, wherein each of the reflecting portions and each of the refracting portions is perpendicular to a corresponding straight line from the deflection device as a reference. It is characterized in that it is configured to emit in any direction.

  According to the fourth aspect of the present invention, the light for scanning can be irradiated to a range included in substantially the same plane perpendicular to the one straight line.

  A laser radar device according to a fifth aspect of the present invention is the laser radar device according to the fourth aspect, wherein a path of light emitted from each of the refracting portions and each reflecting portion is perpendicular to the plane of the path so as to be included in one reference plane. It is characterized in that a prism for adjusting the position in the normal direction is provided for each of the refracting portions or for each of the reflecting portions.

  According to the fifth invention, the light for scanning can be irradiated to the range included in the same plane perpendicular to the first rotation axis.

  A laser radar device according to a sixth aspect of the present invention is the laser radar device according to the first to fifth aspects, wherein the rotation angle of the peristaltic reflection surface in the deflection device and the light source are provided so that light does not hit between the adjacent refracting portions or the reflecting portions. And a controller configured to control the light output from the light source.

  According to the sixth aspect of the present invention, it is possible to prevent the occurrence of inconvenience in the light irradiation by the laser radar device and the collection of information based thereon by the light falling between the adjacent refracting portions or the reflecting portions.

A laser radar device according to a seventh invention is the laser radar device according to any one of the first to sixth inventions,
A beam splitter disposed between the light source and the peristaltic reflective surface of the deflection device;
A light receiving device for observing a portion of the return light from the deflection device divided by the beam splitter is provided.

  According to the seventh invention, it is possible to split the return light emitted from the laser radar device to the outside, reflected by the external object and returned by the beam splitter, and to observe it with the light receiving device.

It is a perspective view showing the principal part of the laser radar device concerning one embodiment of the present invention. It is a top view of the laser radar apparatus of FIG. It is a side view of the laser radar apparatus of FIG. It is a figure which shows the course of the light in each reflection part and refractive part which comprise the element group of the laser radar apparatus of FIG. It is a figure which shows the course of the light in the other reflection part which comprises the element group of the laser radar apparatus of FIG. It is a perspective view which shows a mode that the prism group was provided in the laser radar apparatus of FIG. It is a figure which shows a mode that the course of light is adjusted with one prism which comprises the prism group in FIG. It is a figure which shows a mode that the course of light is adjusted by one other prism which comprises the prism group in FIG. It is a perspective view of the deflection | deviation apparatus used for the laser radar apparatus of FIG. It is a block diagram which shows the structure of the laser radar apparatus of FIG. It is a figure which shows the waveform of the light output from the light source of the laser radar apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described using the drawings. FIG. 1 is a perspective view showing the main part of the laser radar device of this embodiment, FIG. 2 is a plan view thereof, and FIG. 3 is a side view thereof. As shown in these figures, the laser radar device 1 includes a light source 2 for outputting light having coherence, a deflector 3 for deflecting light from the light source 2 while deflecting it, and light from the deflector 3 And an element assembly 4 as deflection range expansion means for expanding the angular range of deflection.

  The light source 2 outputs laser light as light having coherence. As the wavelength of the laser light, for example, a wavelength in the range of 750 nanometers to 1.5 micrometers is selected according to the purpose of use of the laser radar device 1. In addition, it is not limited to the said wavelength.

  The deflection device 3 has a peristaltic reflection surface 5 on which the light from the light source 2 is incident. The deflecting device 3 deflects the light from the light source 2 within the range of the first angle α (see FIG. 3) by swinging the peristaltic reflective surface 5 around the first rotation axis 6 perpendicular to the normal thereof. While reflecting on the peristaltic reflection surface 5.

  In the following description, a right-handed XYZ-axis orthogonal coordinate system as shown in FIGS. 1 to 3 is used. The X axis is parallel to the first rotation axis 6. The Y-axis and the Z-axis are parallel to the plane including the optical path from the light source 2 to the element assembly 4. The positive direction of the Y axis is a direction substantially from the peristaltic reflective surface 5 toward the light source 2 or the element assembly 4.

  FIG. 4 is a view showing the path of light in each of the reflecting portions A to F and the refracting portions G to M constituting the element assembly 4, and FIG. 5 is a diagram showing each reflecting portion N to S constituting the element assembly 4 Is a figure which shows the course of the light in. Each of the reflecting portions A to F and N to S reflects light in a deflection direction of a part of the light in each deflection direction from the deflection device 3 in a direction corresponding to each. The reflective surface of each of the reflective portions A to F and N to S is formed of a deposited film of aluminum or the like deposited on the glass surface.

  The refracting portions G to M refract light in the deflection directions other than the deflection direction of the part of the light in each deflection direction from the deflection device 3 in the corresponding directions. Each of the refracting portions G to M is a refracting optical element having an incident surface and an emitting surface, and refracts light according to Snell's law when entering the incident surface and emitting from the emitting surface.

  The element assembly 4 is configured by arranging the 19 reflective portions A to F, the refractive portions G to M, and the reflective portions N to S in this order in the positive direction or the negative direction of the Z axis. The element assembly 4 reflects light from the light source 2 while deflecting the peristaltic reflection surface 5 by the deflection device 3 and deflecting the light within the range of the above-mentioned rotation angle α. The refracting portions G to M and the reflecting portions N to S are disposed so as to sequentially reciprocate and be irradiated.

  The refracting portion J disposed in the middle of the refracting portions G to M is configured such that the light from the light source 2 travels straight as viewed in the Z-axis direction. That is, the entrance surface and the exit surface of the light with respect to the refracting portion J are configured to be orthogonal to the light as viewed in the Z-axis direction. The deflection angle θ of the refracting portion J is zero if the angle formed by the vector b of the emitted light with respect to the vector a of the incident light from the light source 2 when viewed in the Z-axis direction is the deflection angle θ.

  The refracting portions I and K on both sides of the refracting portion J respectively receive the light from the light source 2 in the positive direction of the X axis and the deflection angle .theta. Becomes a unit deflection angle .theta.m (= 360 / 19.apprxeq.18.947). Deflection in the negative direction. Similarly, the refracting portion or the reflecting portion positioned n-th from the central refracting portion J in both directions has a positive direction and a negative direction of the X axis such that the deflection angle θ is n times the unit deflection angle θm. Bias.

  Therefore, the deflection angle θ of each of the reflection portions A to F and N to S and the refraction portions G to M is smaller as it is closer to the center of the arrangement, and larger as it is farther from the center. In the reflecting portions A and S, the deflection angle θ becomes θm × 9 ≒ 170.5 °. Thus, the element assembly 4 has a function of expanding the angular range of deflection of light from the deflection device 3 to approximately 360 °, which is a second angular range larger than the first angular range α.

  As shown in FIG. 3, each of the reflecting portions A to F, N to S and the refracting portions G to M emits corresponding incident light from the deflecting device 3 in a direction perpendicular to one reference straight line. Configured One straight line to be a reference is a straight line parallel to the Z axis in the present embodiment.

  That is, the inclination of the reflecting surface of each of the reflecting portions A to F and N to S with respect to the Z axis is such that light in the corresponding deflection direction from the deflecting device 3 is reflected by the reflecting surface in the direction perpendicular to the Z axis. It is set. In FIG. 3, the optical paths of light to be reflected or refracted are shown for the reflecting portions A and S and the refracting portion J.

  The inclination of the entrance surface and the exit surface of each of the refracting portions G to M with respect to the Z axis is such that light in the corresponding deflection direction from the deflecting device 3 is refracted by the entrance surface and the exit surface in the direction perpendicular to the Z axis. It is set. If the exit surface of each of the refracting portions G to M is parallel to the Z axis, the inclination of the entrance surface with respect to the Z axis is set so that each incident surface deflects the incident light in the direction perpendicular to the Z axis. Be done.

  A beam splitter 11 is arranged between the light source 2 and the peristaltic reflection surface 5 of the deflection device 3. In addition, a light receiving device 12 is provided for observing a portion of the return light from the outside of the laser radar device 1 divided by the beam splitter 11.

  As shown in FIG. 3, in the light source 2, the beam splitter 11 and the light receiving device 12, the light from the light source 2 enters the peristaltic reflecting surface 5 of the deflecting device 3 from the lower side of the element assembly 4 and the return light To be observed in the negative direction of the Z axis relative to the element assembly 4. When viewed in the YZ plane, the angle between the light from the light source 2 and the Y axis is, for example, about 5 to 15 °.

  FIG. 6 shows the laser radar device 1 provided with a prism group 14. As shown in the figure, around the element assembly 4, the paths 13 of light output from the respective reflecting portions A to F and N to S of the element assembly 4 and the refracting portions G to M to the outside of the device are A prism group 14 is provided which adjusts for each of the reflective portions A to F and N to S and the refractive portions G to M. This adjustment is performed such that the paths 13 of light from the reflective portions A to F and N to S and the refractive portions G to M are included in one plane PL which is a reference perpendicular to the Z axis.

  As shown in FIG. 7 and FIG. 8, each of the prisms 15 constituting the prism group 14 is necessary in the Z-axis direction of the path 13 of the light from the corresponding reflecting portions A to F, N to S or the refracting portions G to M. The shape, size, arrangement, and posture are selected according to the adjustment amount dz. The adjustment amount dz of the track 13 is different for each of the reflective portions A to F, N to S or the refractive portions G to M corresponding to the track 13.

  Specifically, for example, assuming that the plane including the path 13 of the light from the refracting portion J in FIG. 3 is one plane PL as the above reference, the other refracting portions G to I, K to L and the reflecting portion For A to F and N to S, a prism 15 is provided to adjust each adjustment amount dz. In this case, for the refracting portion J, since the path 13 is included in the plane PL, the prism 15 is unnecessary.

  Of the refracting portions G to I, K to L, and the reflecting portions A to F, and N to S, those at symmetrical positions with respect to the refracting portion J in the Z-axis direction have the same amount of adjustment dz Since the symbols are different only, the prism 15 having the same shape and size can be used by changing only the posture.

  FIG. 9 is a perspective view of the deflection device 3. As shown in the figure, the deflecting device 3 has a mirror portion 16 having a peristaltic reflection surface 5, a first support portion 17 supporting the mirror portion 16, one end to the mirror portion 16, and the other end to the first support portion The first piezoelectric actuators 18a and 18b are connected to the first and second electrodes 17, respectively. By piezoelectrically driving the first piezoelectric actuators 18a and 18b, the mirror portion 16 can be rotated about the second rotation axis 20 with respect to the first support portion 17.

  The deflection device 3 further includes a second support 19 for supporting the first support 17, and a second piezoelectric actuator 21 having one end connected to the first support 17 and the other end connected to the second support 19. Equipped with By piezoelectrically driving the second piezoelectric actuator 21, the first support portion 17 can be swung about the first rotation axis 6 with respect to the second support portion 19.

  In the deflecting device 3, the first rotation axis 6 is parallel to the X axis, and the light from the light source 2 is reflected to be incident on each of the reflecting portions A to F and N to S and the refracting portions G to M of the element assembly 4. To be arranged.

  Although this deflecting device 3 is the same as that described in the above-mentioned Patent Document 3, the deflecting device 3 is not limited to this, and rotates the peristaltic reflecting surface 5 around the first rotation axis 6 Other MEMS mirrors may be used as long as they have a function.

  FIG. 10 is a block diagram showing each part of the laser radar device 1. As shown in the figure, the laser radar device 1 further includes a light source drive circuit 22 for driving the light source 2, a deflection device drive circuit 23 for driving the deflection device 3, and a detection circuit for capturing received light data as a detection value from the light receiving device 12. 24 and a control unit 25 that controls these.

  The control unit 25 controls the light source drive circuit 22 and the deflection device drive circuit 23 in synchronization to drive the light source 2 and the deflection device 3 in synchronization, thereby pulsing light as shown in FIG. The assembly 4 is irradiated.

  In FIG. 11, a portion indicated by a broken line is a portion temporally or positionally corresponding to a joint portion of each of the reflection portions A to F and N to S and the refraction portions G to M. Light is not output. Thereby, the light from the light source 2 is prevented from being applied to the joint portion of each of the reflection portions A to F and N to S and the refraction portions G to M of the element assembly 4.

  The width of each pulse in FIG. 11 is inversely proportional to the speed at which the light from the peristaltic reflective surface 5 scans the element assembly 4. And since this scanning speed is fluctuate | varied according to the rotation angle of the peristaltic reflective surface 5, a pulse width is adjusted according to this rotation angle. For example, when the operation speed is a slow rotation angle, the pulse width is controlled to be long.

  The control unit 25 causes such pulse light to sequentially enter each of the reflection portions A to F and the refraction portions G to M and N to S of the element assembly 4 for each pulse. As a result, pulsed light is sequentially irradiated over the full 360 ° scan range.

  The control unit 25 causes the detection circuit 24 to perform detection processing on the detection target 27 in synchronization with the driving of the deflection device 3 based on the return light from the detection target 27 of the emitted pulse light. At this time, by detecting a difference between detection data by the detection circuit 24 when the light source 2 is turned on and off, ambient light that causes noise can be filtered and detected.

  Based on the information on the detection object 27 detected in this manner and the rotation angle of the peristaltic reflection surface 5 in the deflection device 3 at that time, the control unit 25 detects the detection object 27 in which angular direction in the scan range You can figure out what to do. At this time, mapping information in which the rotation angle of the peristaltic reflection surface 5 is associated with the angular direction in the scan range is referred to.

  As described above, according to the present embodiment, the light from one light source 2 is output while being deflected by the deflecting device 3 within the range of the first angle α, and this light is output from the reflection part A of the element assembly 4 By F, N to S and the refracting portions G to M, deflection is made in a larger angle range. Thereby, the light output from the deflecting device 3 while being deflected within the range of the first angle α can scan over the entire circumference of approximately 360 ° which is the larger second angle range.

  Therefore, since the power of a motor or the like that increases the weight of the device, and the curved mirror that complicates the optical design are not used, it is possible to provide the laser radar device 1 that has good performance while being small and inexpensive. it can.

  In addition, a deflection extension means can be provided by adopting an element assembly 4 in which a plurality of reflecting portions A to F and N to S and a plurality of refracting portions G to M are arrayed and coupled in a row, or integrally formed. Since the configuration can be made compact, miniaturization of the laser radar device 1 can be achieved more reliably.

  Further, as shown in FIG. 4, each of the reflecting portions A to F and N to S and each of the refracting portions G to M are formed by the vector a of the corresponding incident light from the deflecting device 3 and the vector b of the emitted light. The smaller the angle θ is, the closer to the center of the arrangement of the reflective portions A to F and N to S and the refractive portions G to M. Therefore, the deflection direction of the light from the element assembly 4 can be continuously changed as in the case where the deflection direction of the light from the deflection device 3 changes.

  In addition, since each of the reflecting portions A to F and N to S and each of the refracting portions G to M are configured to emit corresponding incident light from the deflecting device 3 in a direction perpendicular to one reference straight line. Light for scanning can be irradiated to a range substantially included in the same plane perpendicular to the one straight line.

  Also, a direction perpendicular to the plane of the light path such that the light path emitted from each of the refracting portions G to M and each of the reflecting portions A to F and N to S is included in one reference plane PL. Since the prisms 15 for adjusting the position of each of the refractive portions G to M or the reflective portions A to F and N to S are provided, scanning can be performed along the plane PL.

  In addition, the rotation angle of the peristaltic reflection surface 5 in the deflection device 3 and the output of the light from the light source 2 are set so that light does not hit between the adjacent refractive portions G to M or the reflection portions A to F and N to S. Since the control is performed, it is possible to prevent the occurrence of inconvenience in the irradiation of light by the laser radar device 1 and the collection of information based thereon.

  Although the embodiments of the present invention have been described above, the present invention is not limited thereto. For example, the numbers of the refractive portions G to M and the reflective portions A to F and N to S are not limited to the above-described example. By increasing this number, the resolution of the object detection by the laser radar device 1 can be improved.

  Further, the dimension in the Z-axis direction of the refracting portions G to M and the reflecting portions A to F, N to S is elongated to expand the observation region by the laser radar device 1 in the direction of the Z axis, realizing a three-dimensional laser radar You may do it.

  In this case, in addition to the 360 ° scan range around an axis parallel to the Z axis, each time the light from the peristaltic reflective surface 5 passes through each of the reflecting portions A to F and N to S and the refracting portions G to M, A range corresponding to the dimension in the Z-axis direction of each of the reflecting portions A to F and N to S and the refracting portions G to M is sequentially scanned also around the first rotation axis 6 parallel to the X axis. .

  DESCRIPTION OF SYMBOLS 1 ... laser radar apparatus, 2 ... light source, 3 ... deflection apparatus, 4 ... element aggregate, 5 ... peristaltic reflective surface, 6 ... 1st axis of rotation, 11 ... beam splitter, 12 ... light receiving apparatus, 13 ... course, 14 ... Prism group 15 Prism 21 Mirror portion 17 First support portion 18a, 18b First piezoelectric actuator 19 Second support portion 20 Second rotational axis 21 Second piezoelectric actuator 22 ... light source drive circuit, 23 ... deflection device drive circuit, 24 ... detection circuit, 25 ... control unit, 27 ... detection object, A to F, N to S ... reflection portion, G to M ... refraction portion, PL ... plane.

Claims (7)

A light source that outputs light having coherence;
A light from the light source is provided, having a peristaltic reflection surface that reflects the light from the light source, and deflecting the reflected light within a first angle range by swinging the peristaltic reflection surface around the first rotation axis. A deflector that reflects
And deflection range expansion means for expanding an angular range of deflection of light from the deflection device to a second angular range larger than the first angular range,
The deflection range extending means is
A plurality of reflecting portions for reflecting light in one of the plurality of deflection directions from the deflection device in the respective reflection directions;
A laser radar device comprising: a plurality of refracting portions for refracting light in deflection directions other than the part of the light in a plurality of deflection directions from the deflection device in respective refracting directions.   The laser radar device according to claim 1, wherein the deflection range extending means is an element assembly including the plurality of reflecting portions and the plurality of refracting portions arranged in a line. The plurality of refracting portions are arrayed on the side of the array center of the element assembly, and the plurality of reflecting portions are arrayed on both sides of the array.
In each of the refracting portions and the reflecting portions, the angle formed by the vector of the corresponding incident light from the deflecting device and the vector of the outgoing light thereof is smaller as the angle is closer to the center of the array. The laser radar apparatus of description.   Each of the reflectors and the refractors is configured to emit the corresponding incident light from the deflector in a direction perpendicular to one reference straight line. The laser radar device according to any one of the preceding claims.   A prism for adjusting the position of the path in a direction perpendicular to the plane of each of the refractors or the refractor so that the course of the light emitted from each of the refractors and the reflectors is included in one reference plane. 5. The laser radar device according to claim 4, wherein each of the reflectors is provided.   The control unit controls the rotation angle of the peristaltic reflection surface in the deflection device and the output of the light from the light source so that light does not hit between the adjacent refracting portion or the reflecting portion. The laser radar device according to any one of Items 1 to 5. A beam splitter disposed between the light source and the peristaltic reflective surface of the deflection device;
The laser radar device according to any one of claims 1 to 6, further comprising: a light receiving device for observing a part of the return light from the deflection device divided by the beam splitter.