CN113552580B

CN113552580B - Laser radar and method for detecting target object by using same

Info

Publication number: CN113552580B
Application number: CN202010306959.3A
Authority: CN
Inventors: 毛胜平; 向少卿
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2020-04-17
Filing date: 2020-04-17
Publication date: 2024-07-09
Anticipated expiration: 2040-04-17
Also published as: CN113552580A

Abstract

The present invention provides a laser radar including: a laser emitting unit including an array of a plurality of lasers configured to emit a detection laser beam for detecting a target object; the echo detection unit comprises an array of a plurality of detectors and is configured to receive echoes of the probe beam reflected by the target object; and a swing mirror swingable back and forth about a rotation axis thereof, the swing mirror having a reflecting surface configured to receive the measuring laser beam from the laser emitting unit and reflect to the outside of the laser radar for detecting a target object, and to receive an echo from the target and reflect to the echo detecting unit.

Description

Laser radar and method for detecting target object by using same

Technical Field

The disclosure relates to the field of photoelectric technology, in particular to a laser radar based on a swinging mirror swinging reciprocally and a method for detecting a target object by using the laser radar.

Background

The laser radar is a radar system for detecting the position, speed and other characteristic quantities of a target by emitting laser beams, and is an advanced detection mode combining laser technology and photoelectric detection technology. The laser radar is widely applied to the fields of automatic driving, traffic communication, unmanned aerial vehicle, intelligent robot, resource exploration and the like due to the advantages of high resolution, good concealment, strong active interference resistance, good low-altitude detection performance, small volume, light weight and the like.

Lidar is typically composed of a transmitting system, which typically includes various forms of lasers and transmitting optical systems, a receiving system, which typically includes photodetectors and receiving optical systems in various forms, information processing, and the like. How to optimize the mechanical and optical path structures of the laser radar, thereby improving the receiving and transmitting efficiency, measuring range and enabling the laser radar to be more miniaturized is a problem which is continuously needed to be solved by technicians in the related field.

The matters in the background section are only those known to the public and do not, of course, represent prior art in the field.

Disclosure of Invention

The invention provides a laser radar and a method for detecting an object by using the laser radar.

According to one aspect of the invention, a lidar comprises:

a laser emitting unit including an array of a plurality of lasers configured to emit a detection laser beam for detecting a target object;

an echo detection unit comprising an array of a plurality of detectors configured to receive echoes of the detection laser beam after reflection by a target object; and

And a swing mirror swingable back and forth around a rotation axis thereof, the swing mirror having a reflecting surface configured to receive the detection laser beam from the laser emitting unit and reflect to the outside of the laser radar for detecting a target object, and to receive an echo from the target object and reflect to the echo detecting unit.

According to one aspect of the present invention, the swing mirror has a single reflecting surface, and the laser radar further includes a turning mirror, a shaping lens, and a beam splitter disposed in this order between the laser array and the swing mirror, wherein the beam splitter is configured to receive the detection laser beam and emit the detection laser beam to the shaping lens, and after being modulated by the shaping lens, the detection laser beam is reflected by the turning mirror onto the reflecting surface of the swing mirror, and the swing mirror receives an echo from a target object and reflects onto the turning mirror, and reflects onto the shaping lens and emits the beam splitter by the turning mirror, and is further incident on the echo detection unit.

According to one aspect of the present invention, the swing mirror includes a first reflecting surface and a second reflecting surface parallel to each other, wherein the first reflecting surface is for receiving and reflecting the detection laser beam, the second reflecting surface is for receiving and reflecting the echo, the laser radar further includes a transmitting lens group, a receiving lens group, a first turning mirror, and a second turning mirror,

The emission lens group is arranged between the laser array and the swinging mirror, and the first turning mirror is arranged at the downstream of the optical path of the first reflecting surface, so that the emission lens group can receive the detection laser beam from the laser array, make the detection laser beam incident on the first reflecting surface after shaping and reflected to the first turning mirror, and exit after being reflected by the first turning mirror;

the receiving lens group is arranged between the detector array and the swinging mirror, and the second turning mirror is arranged at the upstream of the optical path of the second reflecting surface, so that the turning mirror can reflect the echo to the second reflecting surface, reflect the echo by the second reflecting surface and make the echo incident to the detector array after converging by the receiving lens group.

According to one aspect of the invention, the oscillating mirror comprises a first reflecting surface and a second reflecting surface which are non-parallel, wherein the first reflecting surface is used for receiving and reflecting the detection laser beam, the second reflecting surface is used for receiving and reflecting the echo, the laser radar further comprises a transmitting lens group, a receiving lens group, a first turning mirror and a second turning mirror,

The first turning mirror and the emission lens group are sequentially arranged between the laser array and the swinging mirror, so that detection laser beams emitted by the laser array are reflected by the first turning mirror and are shaped by the emission lens group and then are incident on the first reflecting surface;

The second turning mirror and the receiving lens group are sequentially arranged between the detector array and the swinging mirror, so that the second reflecting surface can reflect the echoes to the receiving lens group, and the echoes are converged by the receiving lens group and reflected by the second turning mirror and then are incident to the detector array.

According to one aspect of the invention, the angle between the optical axis of the detection laser beam incident on the first reflecting surface and the optical axis of the echo reflected by the second reflecting surface is twice the angle between the first reflecting surface and the second reflecting surface.

According to an aspect of the present invention, one of an upper region and a lower region of the reflecting surface of the oscillating mirror is for receiving the detection laser beam from the laser emitting unit and reflecting to the outside of the laser radar, and the other of the upper region and the lower region of the reflecting surface of the oscillating mirror is for receiving an echo from the target object and reflecting to the echo detecting unit.

According to one aspect of the invention, the laser array comprises a plurality of lasers arranged along the direction of the axis of rotation of the oscillating mirror, and the detector array comprises a plurality of detectors arranged along the direction of the axis of rotation of the oscillating mirror.

According to one aspect of the invention, the laser radar further comprises a swinging mirror driving mechanism, wherein the swinging mirror driving mechanism is connected with the swinging mirror and can drive the swinging mirror to swing around a rotating shaft of the swinging mirror, and the swinging mirror driving mechanism is arranged in a space surrounded by the first reflecting surface and the second reflecting surface.

According to one aspect of the invention, the swing mirror comprises a longitudinal axis and a swing mirror body, the reflecting surface is positioned on the swing mirror body, and the swing mirror body is mounted on the fixed shaft through a swing arm.

According to one aspect of the invention, the swing mirror comprises a frame and a swing mirror body, wherein the reflecting surface is positioned on the swing mirror body, and the swing mirror body is installed in the frame through a torsion beam.

According to one aspect of the invention, the array of lasers comprises a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the axis of rotation, each column comprising at least one laser, wherein the lasers of different columns are mutually staggered along the direction of the axis of rotation.

According to one aspect of the invention, the array of lasers comprises a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the rotation axis, the fields of view corresponding to each column of lasers being separated from each other.

According to one aspect of the invention, the array of lasers is driven to emit light in a manner that lists light, spaced within a single column.

According to one aspect of the invention, the oscillating mirror is configured such that the direction of the detection laser beam from which the lidar ultimately emits and the direction of the echo received by the lidar are substantially parallel.

According to one aspect of the invention, the oscillating mirror oscillates back and forth about its axis of rotation through an angle of at most 60 degrees, wherein the array of lasers is unevenly distributed, wherein the density of lasers is high at intermediate positions along the longitudinal direction of the lidar and low at positions on both sides.

The invention also provides a method for detecting the target object by using the laser radar.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate and explain the exemplary embodiments of the disclosure and together with the description serve to explain the disclosure, and do not constitute an undue limitation on the disclosure. In the drawings:

FIG. 1 shows a schematic diagram of a lidar according to an embodiment of the invention;

FIG. 2 shows a schematic diagram of a lidar of an off-axis configuration according to an embodiment of the present invention;

FIG. 3 shows a schematic diagram of a lidar of an off-axis configuration according to another embodiment of the present invention;

FIG. 4 shows a schematic diagram of a co-planar received lidar according to an embodiment of the invention;

FIG. 5 illustrates a swing mirror according to a preferred embodiment of the invention in which a drive mechanism is disposed internally;

FIGS. 6A and 6B are schematic diagrams showing a swing mirror mounting and a rotating electrical machine according to a preferred embodiment of the present invention;

FIGS. 7A and 7B are schematic diagrams showing a swing mirror mounting and a rotating electrical machine according to a preferred embodiment of the present invention;

FIGS. 8 and 9 show two configurations of a swing mirror, respectively;

FIGS. 10 and 11 illustrate an arrangement of laser arrays according to a preferred embodiment of the present invention;

FIG. 12 shows a schematic diagram of the emission timing of a laser array; and

FIG. 13 shows a schematic of a spot combining normal scan and retrace for a frame when operating in conjunction with a fold mirror.

Detailed Description

Hereinafter, only certain exemplary embodiments are briefly described. As will be recognized by those of skill in the pertinent art, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not as restrictive.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more of the described features. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be fixedly connected, detachably connected, or integrally connected, and may be mechanically connected, electrically connected, or may communicate with each other, for example; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present invention, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is less level than the second feature.

The following disclosure provides many different embodiments, or examples, for implementing different features of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples, which are for the purpose of brevity and clarity, and which do not themselves indicate the relationship between the various embodiments and/or arrangements discussed. In addition, the present invention provides examples of various specific processes and materials, but one of ordinary skill in the art will recognize the application of other processes and/or the use of other materials.

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.

Fig. 1 shows a lidar 10 according to an embodiment of the invention, which is described in detail below with reference to fig. 1. As shown in fig. 1, the lidar 10 includes a laser light emitting unit 11, an echo detection unit 12, and a swing mirror 13. Wherein the laser emitting unit 11 comprises an array of a plurality of lasers 111, for example arranged in a direction perpendicular to the plane of the paper in fig. 1. The laser 111 is mounted on a circuit board and configured to emit a detection laser beam L1 for detecting a target object. The array of lasers 111 may be an array of lasers formed from a single laser or a linear or an area array of lasers, including edge-emitting lasers or vertical cavity surface emitting lasers. The detection laser beam L1 is emitted from the laser radar 10, then enters the target object, undergoes diffuse reflection on the target object, and returns a partial reflection echo L2 to the laser radar 10. The echo detection unit 12 comprises an array of a plurality of detectors 121, for example arranged in a direction perpendicular to the paper surface in fig. 1, configured to receive echoes of the detection laser beam after reflection by the target object. The detector 141 includes, but is not limited to, a photodiode, siPM, SPAD, etc. photodetector, which converts the echo L2 into an electrical signal that reflects the intensity of the echo L2. The processing device of the laser radar can calculate the distance to obtain the target object according to the time difference between the emission time of the detection laser beam and the receiving time of the echo, namely the flight time TOF (Time of Flight). In the laser radar, the radar harness is ensured by the number of the channels of the detectors in the vertical direction, and the laser array can be an independent light source corresponding to the number of the detectors one by one or can be a segmented line light source for simultaneously illuminating a plurality of units.

According to a preferred embodiment of the present invention, the laser array comprises a plurality of lasers arranged along the direction of the axis of rotation OX of the oscillating mirror, and the detector array comprises a plurality of detectors arranged along the direction of the axis of rotation of the oscillating mirror. In the array of lasers, the lasers are preferably unevenly distributed, for example in the longitudinal direction of the lidar, the density of the lasers being high in the middle of the array and low in the positions on both sides. In this way, the detection accuracy of the field of view in the approximately horizontal direction in the laser radar detection can be effectively improved, and the horizontal field of view is the most critical part in the field of view of the laser radar, so that the improvement of the detection accuracy of the field of view in the horizontal direction has important significance for the laser radar. Correspondingly, the detector array may also take on a non-uniformly distributed manner.

The oscillating mirror 13 can oscillate back and forth about its axis of rotation OX, as indicated by the arrow R in fig. 1. The oscillating mirror 13 has a reflecting surface 131 parallel to the rotation axis OX. The oscillating mirror 13 is located downstream of the optical path of the laser emission unit 11 and upstream of the echo detection unit 12, and the reflecting surface 131 may receive the detection laser beam L1 and reflect to the outside of the laser radar for detecting a target object, and may receive the echo L2 and reflect the echo toward the echo detection unit 12. As shown in fig. 1, at the present position, the detection laser beam L1 is incident on the reflection surface 131 and reflected outside the laser radar, and the echo L2 is incident on the reflection surface 132 and then reflected toward the echo detection unit 12. As the oscillating mirror 13 oscillates back and forth about its axis of rotation OX, it can scan the detection laser beam L1 in different outgoing directions and receive echoes from different directions.

In the exemplary embodiment shown in fig. 1, the oscillating mirror 13 has a single reflecting surface 131 for both scanning the outgoing probe laser beam L1 and for receiving the radar echo L2. As further shown in fig. 1, the laser radar 10 further includes a beam splitter 14, a shaping lens 15, and a turning mirror 16 disposed in sequence between the array of lasers 111 and the oscillating mirror 13, wherein the beam splitter 14 is configured to receive the detection laser beam L1 from the lasers 111 and allow it to exit to the shaping lens 15, and the shaping lens 15 is, for example, a collimating lens, for collimating and modulating the detection laser beam L1 and exiting to the turning mirror 16, and the turning mirror 16 may include a reflecting mirror for reflecting the detection laser beam L1 onto a reflecting surface 131 of the oscillating mirror 13. Meanwhile, the swing mirror 13 receives the echo L2 from the target object, reflects the echo L2 onto the turning mirror 16, reflects the echo L2 onto the shaping lens 15 via the turning mirror 16, and outputs the echo L2 onto the beam splitter 14, and then is incident on the echo detection unit 12. One skilled in the art will readily appreciate that the beamsplitter 14 may be a small aperture mirror or a PBS polarizing beamsplitter.

The lidar 10 shown in fig. 1 has a coaxial structure in which a transmitting optical path and a receiving optical path substantially coincide, and a short-distance blind area generated by such a structure is small. The present invention is not limited to this, and can be applied to a laser radar of a different-axis structure. The following description refers to the accompanying drawings.

Fig. 2 shows a lidar 20 of an off-axis configuration according to an embodiment of the invention. The difference of the lidar 20 in fig. 2 from the lidar 10 shown in fig. 1 is described with emphasis.

As shown in fig. 2, the laser radar 20 includes a laser emitting unit 11, an echo detecting unit 12, and a swinging mirror 23, where the laser emitting unit 11 includes an array formed by lasers 111, and the echo detecting unit 12 includes an array formed by detectors 121, which are the same as or similar to the embodiment shown in fig. 1, and will not be described again here. In the embodiment of fig. 2, the oscillating mirror 23 is a double-sided oscillating mirror, and includes a first reflecting surface 231 and a second reflecting surface 232 parallel to each other, where the first reflecting surface 231 is configured to receive and reflect the detection laser beam L1, and the second reflecting surface 232 is configured to receive and reflect the echo L2. In addition, the laser radar 20 further includes a transmitting lens group 25, a receiving lens group 26, a first turning mirror 27, and a second turning mirror 28. Wherein the emission lens 25 is disposed between the laser 211 and the oscillating mirror 23, and the first refractive mirror 27 is disposed downstream of the optical path of the first reflective surface 231, so that the emission lens 25 can receive the detection laser beam from the laser 111, and after shaping, the detection laser beam is incident on the first reflective surface 231 and reflected to the first refractive mirror 27, and is reflected by the first refractive mirror 27 and exits. The receiving lens set 26 is disposed between the detector 121 and the oscillating mirror 23, and the second turning mirror 28 is disposed upstream of the optical path of the second reflecting surface 232, so that the second turning mirror 28 may reflect the echo L2 onto the second reflecting surface 232, reflect from the second reflecting surface 232, and converge by the receiving lens set 26 to be incident on the detector array. Wherein the laser array is located at the focal plane of the transmit lens group 25 and the detector array is located at the focal plane of the receive lens group 26.

Fig. 3 shows a lidar 30 of an off-axis structure according to another embodiment of the invention, and the differences between the lidar 30 of fig. 3 and the lidar 10 of fig. 1 are described with an emphasis.

As shown in fig. 3, the laser radar 30 includes a laser emitting unit 11, an echo detecting unit 12, and a swinging mirror 33, where the laser emitting unit 11 includes an array formed by lasers 111, and the echo detecting unit 12 includes an array formed by detectors 121, which are the same as or similar to the embodiment shown in fig. 1, and will not be described again here. Wherein the oscillating mirror 33 comprises a first reflecting surface 331 and a second reflecting surface 332 which are non-parallel, wherein the first reflecting surface 331 is adapted to receive and reflect the detection laser beam L1, and the second reflecting surface 332 is adapted to receive and reflect the echo L2. The lidar 30 additionally comprises a transmitting lens group 25, a receiving lens group 26, a first turning mirror 27 and a second turning mirror 28. The first turning mirror 27 and the emission lens group 25 are sequentially disposed between the array of lasers 111 and the oscillating mirror 33, so that the detection laser beam L1 emitted from the lasers 111 is reflected by the first turning mirror 27 and is shaped by the emission lens group 25 to be incident on the first reflecting surface 331. The second turning mirror 28 and the receiving lens set 26 are sequentially disposed between the array of the detector 121 and the oscillating mirror 33, so that the second reflecting surface 332 may reflect the echo L2 onto the receiving lens set 26, and after being converged by the receiving lens set 26 and reflected by the second turning mirror 28, the echo L2 is incident on the array of the detector 121.

Further, according to a preferred embodiment of the present invention, as shown in fig. 3, the angle between the optical axis V1 of the probe laser beam incident on the first reflecting surface and the optical axis V2 of the echo reflected by the second reflecting surface (i.e., 2θ shown in fig. 3) is twice the angle between the first reflecting surface and the second reflecting surface (i.e., θ shown in fig. 3).

In addition, according to an embodiment of the present invention, the oscillating mirror 33 is configured such that the direction of the detection laser beam (e.g., V11 in fig. 3) from which the laser radar finally exits and the direction of the echo (e.g., V22 in fig. 3) received by the laser radar are substantially parallel.

Fig. 4 shows a lidar 40 according to an embodiment of the present invention, as shown in fig. 4, in which a single-sided swing mirror 43 is used, and a reflecting surface of the swing mirror 43 is divided into an upper region and a lower region, one for receiving a detection laser beam from the laser emitting unit and reflecting to the exterior of the lidar, and the other for receiving an echo from a target object and reflecting to the echo detecting unit. In fig. 4, the upper region is shown for receiving the probe laser beam L1 and reflecting it off, and the lower region is shown for receiving the echo. The invention is not limited thereto and may be used upside down. The receiving and transmitting efficiency of the lidar 40 is high by the coplanar receiving mode of the up-down arrangement shown in fig. 4, and the lidar is suitable for long-distance detection. Those skilled in the art will readily appreciate that the number of lasers 111 and detectors 121, as well as the number and orientation of light rays, shown in fig. 4 are merely exemplary, and that any number of lasers 111 and detectors 121 may be provided according to actual needs and are within the scope of the present invention.

According to one embodiment of the present invention, the swing mirror swings back and forth about its rotation axis to a range of 60 degrees or less. Therefore, almost all scanning time can be utilized, and the time utilization rate is high.

In the embodiments of fig. 1-4, the swinging of the swinging mirror around the axis may adopt a sinusoidal scanning mode, and light is emitted at an equal angle during the scanning process; the method can also adopt a uniform scanning mode, and the two ends of the uniform section are provided with an acceleration section and a deceleration section. The frequency of the horizontal reciprocating swing scan is matched to the radar frame rate. Let the radar frame rate be 10 hz. If the normal scan and the retrace of the swinging mirror are combined into one frame (the light emission of the normal scan and the retrace is misplaced in the horizontal direction), the swinging frequency of the swinging mirror is 10 Hz; if the scan is one frame and the retrace is the next frame, the swing frequency of the swing mirror is 5 Hz.

In the lidar shown in fig. 1 to 4, a detection field of view of the lidar in the vertical direction is realized by an array of a plurality of lasers arranged along the rotation axis direction of the oscillating mirror; the scanning field of view of the laser radar on the horizontal plane is realized through the swing scanning of the swing mirror around the rotating shaft of the swing mirror in the horizontal plane.

The laser radar can further comprise a swinging mirror driving mechanism, wherein the swinging mirror driving mechanism is connected with the swinging mirror and can drive the swinging mirror to swing around a rotating shaft of the swinging mirror, and the swinging mirror driving mechanism is arranged in a space surrounded by the first reflecting surface and the second reflecting surface. As shown in fig. 5, the swing drive mechanism includes a rotary motor 31, a lower bearing 32, an upper bearing 35, and a main shaft 36. The spindle 36 is for supporting the oscillating mirror 33, and is driven by the rotary motor 31. An upper bearing 35 and a lower bearing 32 are respectively connected to the upper and lower parts of the main shaft for connection to the swing mirror 33. Thus, the oscillating mirror 33 can be driven to oscillate back and forth as the rotary motor 31 oscillates back and forth. And the swing mirror driving mechanism is located in the space surrounded by the first reflecting surface 331 and the second reflecting surface 332, so that the height of the laser radar is further reduced, and the upper end and the lower end do not exceed the axial range of the reflecting surfaces. In addition, as shown in fig. 5, the lidar further comprises a goniometer mirror 34, for example for angular measurement by the PSD, to obtain the current angular orientation of the oscillating mirror 33. Alternatively, an opto-electronic code wheel may be used for angular measurement, see in particular the description below with respect to fig. 7A.

Fig. 6A and 7A illustrate two different types of drive mechanisms. In the embodiment of fig. 6A, a single-sided oscillating mirror is used, fixed to the spindle, between the upper and lower bearings. As shown in fig. 6A and 6B, when currents in different directions are introduced into the driving coil (stator), torsion forces in different directions are generated on the lateral magnetizing magnetic ring (rotor), so that the main shaft is driven to swing along different directions, and the swinging mirror is correspondingly driven to swing. As shown in fig. 6B, the lateral magnetizing magnetic ring (mover) may not be a complete 360-degree magnetic ring, and only the swing range of the swing mirror needs to be covered by the lateral magnetizing magnetic ring (mover). In the embodiment of fig. 7A, a turntable is mounted above the swing motor, which can be driven by the swing motor. Fig. 7B shows the principle of the wobble motor, in which when currents in different directions are supplied to the coil windings (stators), the magnetic ring (rotor) can be driven to rotate in different directions, and the magnetic ring (rotor) is driven to be fixedly connected with the turntable. The swinging mirror is fixedly arranged on the rotary table, so that the swinging mirror can swing synchronously with the rotary table. The two sets of driving coils are shown in the drawings, and the invention is not limited thereto, and multiple sets of driving coils may be arranged to improve the linearity of driving and thus the swing angle. In addition, the laser radar system also comprises a code disc, wherein the code disc is arranged at the bottom of the oscillating mirror and is used for measuring and encoding the rotation movement of the oscillating mirror, so that the current position and angle of the oscillating mirror can be known by the laser radar control system.

Fig. 8 and 9 show two configurations of the oscillating mirror, respectively. In the embodiment of fig. 8, the oscillating mirror comprises a longitudinal axis and an oscillating mirror body, the reflecting surface being located on the oscillating mirror body, the oscillating mirror body being mounted on the fixed shaft by means of an oscillating arm. The back of the swing mirror main body can be adhered with a magnet, and the energized stator coil is utilized to generate mutual exclusion or attraction force, so that the swing mirror main body swings back and forth around the longitudinal axis. The structure shown in fig. 8 can reduce the vertical height of the swing mirror.

According to the embodiment, the height of the swinging mirror basically limits the total height of the laser radar, and meanwhile, a very flat laser radar system can be still realized on the premise of keeping a large caliber, and the height of the swinging mirror is basically the height of the laser radar. Lidars can be classified into various types according to their functions, including lidars for autopilot, lidars for sweeping robots, and lidars for automated guided vehicles. In addition, lidars may be mounted at different locations. Taking a vehicle-mounted lidar as an example, it may be mounted on the roof of a vehicle as the primary radar, it may be mounted on the front of the vehicle (e.g., integrated in the vehicle lights) as the forward radar, or it may be mounted on the side of the vehicle as the lateral radar. By implementing a flattened lidar, the lidar can be conveniently integrated in various locations of the vehicle, such as in a vehicle lamp or in the vehicle body, reducing changes and effects on the appearance of the vehicle.

In the embodiment of fig. 9, the swing mirror includes a frame and a swing mirror body, the reflecting surface is located on the swing mirror body, and the swing mirror body is mounted in the frame through a torsion beam. The back of the swing mirror main body can be adhered with a magnet, and the energized stator coil is utilized to generate mutual exclusion or attraction force, so that the swing mirror main body swings back and forth around the axis OX in the frame. The structure of fig. 9 is more compact in the horizontal direction than the structure of fig. 8. In the configurations of fig. 8 and 9, a PSD sensor may be used for angle measurement. The manner in which the angle measurement is performed using the PSD sensor is not described in detail herein.

Fig. 10 shows an arrangement of lasers 111 according to a preferred embodiment of the invention, wherein the array of lasers 111 comprises a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the rotation axis, shown as two columns, each column comprising at least one laser, wherein the lasers of different columns are mutually staggered along the direction of the rotation axis. Through arranging encryption in a staggered manner in the vertical direction, the arrangement height in the vertical direction can be reduced, and the resolution in the vertical direction is improved. In addition, although not shown in fig. 10, it will be readily understood by those skilled in the art that the two sets of lasers in fig. 10 are preferably offset from each other in a direction perpendicular to the plane of the drawing, thereby facilitating placement of the lasers.

Fig. 11 shows an arrangement of a laser 111 according to another preferred embodiment of the invention. As shown in fig. 11, the array of lasers includes a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the rotation axis, and in fig. 11, two columns of lasers 111-1 and 111-2 are shown, respectively, with the fields of view corresponding to each column of lasers being separated from each other. Taking 60 degrees as an example of the horizontal view field of the laser radar, the first row of lasers 111-1 and the second row of lasers 111-2 can be used for detecting different horizontal view fields respectively, for example, the first row of lasers 111-1 is used for detecting a view field of 30 degrees on the left side in the horizontal view field, the second row of lasers 111-2 is used for detecting a view field of 30 degrees on the right side in the horizontal view field, and the two rows of lasers can cover a view field of 60 degrees after being spliced. In this way, the swing amplitude required for swinging the mirror can be reduced, for example by half.

Fig. 12 shows a lighting strategy according to a preferred embodiment of the invention: the lights are listed, and the lights are emitted at intervals in a single column. The arrangement of the laser array is schematically shown in fig. 12, for example a column of lasers, which contains for example 9 lasers. When the probe beam is emitted, a pattern of light emission at intervals within a single column by the listed light is adopted. I, ii, iii, and iv in fig. 12 represent the four horizontal light exit positions of the oscillating mirror. First, at a first light-emitting position, a plurality of lasers are driven to emit and detect; the oscillating mirror then oscillates to a second, horizontal light exit position ii and drives the laser to exit, and then similarly oscillates to third and fourth, horizontal light exit positions. In addition, the four horizontal light exit positions shown in FIG. 12 are merely exemplary, and the oscillating mirror may include a greater or lesser number of light exit positions. Wherein for a column of lasers, it is preferable to avoid that adjacent lasers emit light simultaneously, thereby ensuring eye safety. For this purpose, for example, the plurality of lasers of the a-sequence may be first driven to emit light (positions 1, 4, 7) at regular intervals, the plurality of lasers of the B-sequence may be driven to emit light (positions 2, 5, 8) after the lasers are completely emitted and the detection and reception of the corresponding channels are completed, and the lasers of the C-sequence may be finally driven to emit light (positions 3, 6, 9). The time interval between adjacent column sequences is related to the number of wobble facets and the horizontal resolution of the system. This scanning approach is significant for increasing the eye-safe threshold, on the other hand, even at very high lateral angular resolutions, the lateral minimum listed light time interval Δt ₂ will still be much larger than the row out light time interval Δt ₁; then, in a given eye-safe calculation window (e.g., within a typical 5 milliradian field of view), the eye-safety of the lidar may be limited to adjacent light-emitting units within a single column. In the process of switching the scanning sequence from i to ii, the physical distance between the two front and back light-emitting lasers can be increased through dislocation light-emitting, so that the human eye safety threshold is further effectively improved; in the same column, the principle of pulling the lighting interval of the nearest neighbor unit to the maximum is that the sequence A lights first, then the sequence C and finally the sequence B in the figure. In addition, it will be readily understood by those skilled in the art that the plurality of lasers of the a-sequence in the present invention emit light simultaneously, not meaning that the plurality of lasers of the a-sequence are driven to emit light simultaneously in a strict sense, may be separated by a small time difference, as long as the time difference is much smaller than the time difference between adjacent columns, for example, 10% or less, or 1% of the time difference between adjacent rows. in this case, it can be considered that a plurality of lasers of the a-sequence emit light at the same time. Fig. 12 is a schematic diagram showing light emission of the same column of lasers after scanning by a swing mirror. For example, in the ith column, shown therein is the case where at the 1 st position of the oscillating mirror, the column laser emits light and scans in sequence (9 lasers follow, for example, the order of emission of (1, 4, 7), (2, 5, 8), (3, 6, 9); in column ii, shown therein is the case where the column laser sequentially emits light and scans at position 2 of the oscillating mirror; in column iii, shown therein is the case where the column laser sequentially emits light and scans at position 3 of the oscillating mirror; in column iv, shown therein is the case where the column laser sequentially emits light and scans at position 4 of the oscillating mirror. During operation of the laser, almost all of the swing range of the swing mirror can be utilized, so that the time interval between adjacent columns (i.e., the ith column and the ii th column) is larger, and the angular velocity is smaller, which is beneficial to enlarging the light emission interval of the laser point in a small field of view.

In the embodiments shown in fig. 1-4, the turning mirror may be a fixed mirror. According to another embodiment of the present invention, the folding mirror may also include a swing mirror that swings in a vertical direction. The turning mirror may have, for example, a position state a and a position state B, which are two swing positions in the vertical direction, respectively, and can emit light beams incident thereon in the vertical plane at different angles. At this time, a working mode that the turning mirror swings one-dimensionally and at a small angle to improve resolution during retrace can be adopted. FIG. 13 shows a schematic of a spot combining normal scan and retrace for a frame when operating in conjunction with a fold mirror. As shown in fig. 13, when the swing mirrors 13, 23, 33 scan to the right, the folding mirror is in the position state a; when the oscillating mirror 13, 23, 33 scans back, the oscillating mirror is in the position state B. Thus forming two rows of scanning spots in the vertical direction. The normal scan and the flyback are combined into one frame, and thus, the dislocation encryption is realized. By using the working mode, the super-resolution effect can be realized when the receiving and transmitting units are closely arranged and the vertical resolution is still insufficient.

The above describes a laser radar system for realizing two-dimensional scanning by a vertical array transceiver unit and a horizontal oscillating mirror according to an embodiment of the present invention, wherein the vertical direction determines the angle of view by the position of the array and the optical lens group, and the horizontal direction performs horizontal scanning by the oscillating mirror that reciprocates. Embodiments of the present invention enable a highly compact lidar. In addition, the system height of the embodiment of the invention is basically dependent on the height of the reflector finally (the whole motor can be embedded in the reflector module), so that the scheme can realize a highly compact and flat laser radar system, thereby meeting the requirement of large-scale modulus passenger vehicles. When the swing mirror receives and transmits different surfaces, the effective optical caliber of the transmission and the reception is unequal when the swing mirror rotates by using larger optical caliber of the transmission and the reception, so that the different surfaces receive and transmit can have the complementary characteristic of energy: when the effective emergent energy of the transmitting end is reduced, the effective receiving caliber of the receiving end is increased, so that the range loss caused by the reduction of the transmitting energy is compensated, and vice versa, the actual circle radius of the swing mirror can be smaller, thereby being convenient for reducing the volume and improving the reliability. The embodiment of the invention can realize a high-resolution and long-distance laser radar system.

For the technical scheme of the conventional polygon mirror, the vertical resolution can be improved when the technical scheme is suitable for the condition of larger field of view, for example, more than 100 degrees, and particularly when the technical scheme is matched with a reflecting surface of the polygon mirror, such as a nodding scanner. However, if the scan field is small, the waste of effective scan time is very serious; although the increase in the number of reflecting surfaces of the polygon mirror can be improved, the rotation speed of the polygon mirror at a corresponding fixed frame rate needs to be increased correspondingly, and the time interval of scanning in the horizontal direction needs to be shortened. In order to ensure a certain receiving caliber and thus detect a longer distance, the volume of the polygon mirror is obviously increased along with the increase of the number of the mirror surfaces, so that the uncertainty of the reliability of the increase of the volume of the system is improved. With the existing technical scheme of the resonant mirror, the resonant mirror is mainly limited by high-frequency scanning, so that the caliber is difficult to increase, and the reliability of the high-frequency scanner is also a problem.

The invention uses a reciprocating mirror to scan horizontally, and another dimension (vertical) laser array generates a certain angle of view after passing through an optical system. The adoption of the reciprocating swing horizontal scanning greatly saves scanning time, has high luminous duty ratio, and can be used for emitting light for most of the time, so that high angular resolution can be realized on the premise of not affecting the safety of human eyes, and the transverse scanning interval is very long even under the transverse ultrahigh resolution, thereby being very beneficial to the safety of human eyes. The embodiment of the present invention significantly reduces the volume and the inertia of the oscillating portion is small, and the horizontal direction is a low-speed scan of several hertz to several tens of hertz, compared to the polygon mirror, so that the reliability of the reciprocating oscillating mechanism is high.

In various embodiments of the present invention, the transceiving may be isolated. In addition, the field of view is scalable, and in particular, the horizontal angular resolution can be improved when the horizontal field of view is reduced. The transceiving efficiency can be maximized, and particularly when the different-plane transceiving or the up-down layering transceiving is adopted, the transceiving efficiency limit of the theory can be approached, thereby being beneficial to the remote measurement. The reflection caliber of the low-speed swing mirror can be quite large, so that the measuring range can be improved.

The radar architecture is very efficient and beneficial in terms of system transceiving efficiency and human eye safety, so that the laser light output energy can be reduced, the system power consumption can be reduced, the reliability of a transmitting unit can be provided, the human eye safety is facilitated, or a longer range can be obtained under the condition of using equivalent energy with other similar systems.

Finally, it should be noted that: the foregoing description is only a preferred embodiment of the present invention, and the present invention is not limited thereto, but it is to be understood that modifications and equivalents of some of the technical features described in the foregoing embodiments may be made by those skilled in the art, although the present invention has been described in detail with reference to the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A lidar, comprising:

And a swing mirror swingably around a rotation axis of the swing mirror, the swing mirror being for achieving a reciprocating scanning of the laser radar in a horizontal direction, the swing mirror having a reflecting surface configured to receive a detection laser beam from the laser emitting unit and reflect to an outside of the laser radar for detecting a target object, and to receive an echo from the target object and reflect to the echo detecting unit.

2. The lidar of claim 1, wherein the swing mirror has a single reflective surface, further comprising a beam splitter, a shaping lens, and a turning mirror disposed in sequence between the laser array and the swing mirror, wherein the beam splitter is configured to receive the detection laser beam and exit to the shaping lens, modulated by the shaping lens, reflected by the turning mirror onto the reflective surface of the swing mirror, received by the swing mirror from an object and reflected onto the turning mirror, reflected by the turning mirror onto the shaping lens and exit to the beam splitter, and incident on the echo detection unit.

3. The lidar of claim 1, wherein the wobble mirror comprises a first reflecting surface and a second reflecting surface that are parallel to each other, wherein the first reflecting surface is for receiving and reflecting the probe laser beam, and the second reflecting surface is for receiving and reflecting the echo, the lidar further comprising a transmit lens group, a receive lens group, a first turning mirror, and a second turning mirror,

4. The lidar of claim 1, wherein the wobble mirror comprises first and second non-parallel reflective surfaces, wherein the first reflective surface is configured to receive and reflect the probe laser beam and the second reflective surface is configured to receive and reflect the echo, and further comprising a transmit lens group, a receive lens group, a first refractive mirror, and a second refractive mirror,

5. The lidar of claim 4, wherein an angle between an optical axis of the detection laser beam incident on the first reflecting surface and an optical axis of the echo reflected by the second reflecting surface is twice an angle between the first reflecting surface and the second reflecting surface.

6. The lidar according to claim 2, wherein one of an upper region and a lower region of the reflecting surface of the oscillating mirror is for receiving the detection laser beam from the laser emitting unit and reflecting to the exterior of the lidar, and the other of the upper region and the lower region of the reflecting surface of the oscillating mirror is for receiving an echo from a target object and reflecting to the echo detecting unit.

7. The lidar of any of claims 1-6, wherein the laser array comprises a plurality of lasers arranged along a direction of a rotational axis of the oscillating mirror, and the detector array comprises a plurality of detectors arranged along the direction of the rotational axis of the oscillating mirror.

8. The lidar according to any of claims 3 to 5, further comprising a swing mirror driving mechanism that is connected to the swing mirror and that can drive the swing mirror to swing around its rotation axis, the swing mirror driving mechanism being disposed in a space surrounded by the first reflecting surface and the second reflecting surface.

9. The lidar according to any of claims 1 to 6, wherein the oscillating mirror comprises a longitudinal axis and an oscillating mirror body, the reflecting surface being located on the oscillating mirror body, the oscillating mirror body being mounted on the longitudinal axis by means of an oscillating arm.

10. The lidar of any of claims 1-6, wherein the oscillating mirror comprises a frame and an oscillating mirror body, the reflecting surface being located on the oscillating mirror body, the oscillating mirror body being mounted within the frame by torsion beams.

11. The lidar according to any of claims 1 to 6, wherein the array of lasers comprises a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the rotation axis, each column comprising at least one laser, wherein the lasers of different columns are mutually staggered along the direction of the rotation axis.

12. The lidar according to any of claims 1 to 6, wherein the array of lasers comprises a plurality of columns of lasers distributed along a second direction perpendicular to the direction of the rotation axis, the fields of view corresponding to each column of lasers being separated from each other.

13. The lidar according to any of claims 1 to 6, wherein the array of lasers is driven to emit light in a manner that lists light, emits light at intervals within a single column.

14. The lidar according to claim 1 or 2, wherein the oscillating mirror is configured such that the direction of the detection laser beam from which the lidar finally emerges and the direction of the echo received by the lidar are substantially parallel.

15. The lidar according to any of claims 1 to 6, wherein the oscillating mirror oscillates back and forth around its axis of rotation through an angle of at most 60 degrees, wherein the array of lasers is unevenly distributed, wherein the density of lasers is high at intermediate positions and low at positions on both sides along the longitudinal direction of the lidar.

16. A method of target detection using a lidar according to any of claims 1 to 15.