CN113552554A

CN113552554A - Multi-line laser radar and method for detecting by using multi-line laser radar

Info

Publication number: CN113552554A
Application number: CN202110788412.6A
Authority: CN
Inventors: 王瑞; 李娜; 向少卿; 李一帆
Original assignee: Hesai Technology Co Ltd
Current assignee: Hesai Technology Co Ltd
Priority date: 2017-06-19
Filing date: 2017-06-19
Publication date: 2021-10-26
Anticipated expiration: 2037-06-19
Also published as: CN113447910A; CN107121683A; CN113447910B; CN107121683B; CN113552554B

Abstract

The invention provides a multi-line laser radar which comprises a rotor, a stator and a plurality of lasers, wherein the rotor is arranged on the stator; the method is characterized in that: the detection light emitted by each laser is reflected by the obstacle and then converged on the corresponding detector after passing through the receiving device, and the multi-line laser radar further comprises: the carrier is provided with the plurality of lasers; the lasers are arranged on the supporting body in n rows, and n is more than or equal to 2; the bearing body is arranged in the rotor; a light collimating device; the detection light beams emitted by the laser are driven by the motor to scan around the central axis to generate scanning lines which are distributed densely in the vertical direction so as to obtain the information of the obstacles in the central field of view as much as possible; the light collimating device is disposed within the rotor; the wiring harness of the multi-line laser radar is more than or equal to 16. The invention has the advantages of high vertical angular resolution, high horizontal angular resolution, high scanning frequency, more accurate scanning result and the like.

Description

Multi-line laser radar and method for detecting by using multi-line laser radar

The present application is a divisional application of an invention patent application with application number 201710463616.6 and invention name "multiline lidar based on multiple lasers" filed on 19/6/2017.

Technical Field

The present invention relates to a laser radar, and more particularly, to a multiline laser radar and a method for detecting using the multiline laser radar.

Background

In order to acquire three-dimensional information of a scanned area as much as possible, a multiline laser radar is adopted at present, and more vertical field of view areas can be covered. The beam angle distribution of the multiline laser radar in the market at present adopts an even distribution method within a certain angle range (namely, the vertical angle resolution is a determined value), for example, the vertical angle resolutions of 16-line, 32-line and 64-line laser radars of Velodyne are respectively 2 degrees, 1.33 degrees and 0.43 degrees, and the vertical angle resolutions of 4-line and 8-line laser radars of Ibeo are 0.8 degrees.

The specific application scene of the vehicle-mounted laser radar is mainly to detect pedestrians, vehicles and the like on the ground. This means that the upwardly emitted laser line beam is largely wasted if the field of view is divided equally up and down in the vertical direction.

In addition, if all the field angles are equally divided according to the angle division scheme of the current market products, more lines are needed to achieve higher vertical resolution, which means higher cost, larger volume and lower reliability stability. Due to the limitations of the data capacity of ethernet and the processing speed of onboard CPUs, higher line count lidar (e.g., Velodyne) cannot simultaneously compromise high horizontal angular resolution and high scanning frequency.

If the number of lines is reduced for cost reasons, the angular separation is too large and the target cannot be resolved at a short distance (e.g. 40 m), e.g. at 32 ° for a total vertical field angle, 2 ° separation (vertical resolution), 16 lines are required, then at 40m the laser beam spacing is about 1.4m, and a pedestrian is easily missed.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides the multi-line laser radar based on the plurality of lasers, which has high vertical angle resolution, high horizontal angle resolution, high scanning speed and accurate scanning result.

The purpose of the invention is realized by the following technical scheme:

a multiline lidar based on a plurality of lasers, the multiline lidar comprising a rotor and a stator; the multiline lidar further comprising:

the laser device comprises a carrier, wherein a plurality of lasers are arranged on the carrier; the bearing body is arranged in the rotor;

the laser on the carrier has density distribution in the up-down direction on the projection point of a vertical plane including the main shaft of the optical collimating device; the light collimating means is arranged within the rotor.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, through the density arrangement of the lasers, when the laser beams are designed in a non-uniform distribution manner at a lower beam, a higher vertical angle resolution can be realized, the cost is saved, and the volume is reduced;

2. the laser radar fully considers that obstacles (such as pedestrians, vehicles and the like) needing to be identified in vehicle running are generally gathered near the horizontal line and the ground, so that the density of the central laser beam (horizontal and near horizontal) is enhanced, and the non-uniform laser beam distribution is more scientific and reasonable in the real traffic environment;

3. the laser radar has high vertical angular resolution, and can simultaneously give consideration to high horizontal angular resolution and high scanning frequency due to the reduction of the wiring harness, so that the scanning result is more accurate;

4. the invention adopts a coaxial (the motor, the rotating cavity, the upper circuit board and the like rotate around the middle shaft) transmission mode, thereby greatly reducing the number of transmission parts and occupied space and improving the stability of the system;

5. the motor is arranged at the top (the motor is rotationally fixed at the outer edge of the upper part of the middle shaft, the rotating cavity is positioned at the lower part of the motor and the outer edge along the radial direction of the middle shaft, but not at the upper part of the motor), so that the upper circuit board and the lower circuit board are very close to each other, the communication is convenient, and the maintenance of a transmission system is also very convenient.

Drawings

The disclosure of the present invention will become more readily understood with reference to the accompanying drawings. As is readily understood by those skilled in the art: these drawings are only for illustrating the technical solutions of the present invention and are not intended to limit the scope of the present invention. In the figure:

figure 1 is a schematic view of a carrier and laser according to example 1 of the present invention;

FIG. 2 is a simplified schematic diagram of a multiline lidar based on multiple lasers in accordance with embodiment 3 of the invention;

figure 3 is a schematic view of a carrier and laser according to example 3 of the present invention;

FIG. 4 is a schematic view of a carrier and a laser according to example 4 of the present invention;

FIG. 5 is a schematic view showing the construction of a scanning apparatus in a multiline lidar according to embodiment 4 of the present invention;

fig. 6 is a schematic view of the fixing plate and the groove according to embodiment 6 of the present invention.

Detailed Description

Fig. 1-6 and the following description depict alternative embodiments of the invention to teach those skilled in the art how to make and use the invention. Some conventional aspects have been simplified or omitted for the purpose of teaching the present invention. Those skilled in the art will appreciate that variations or substitutions from these embodiments will be within the scope of the invention. Those skilled in the art will appreciate that the features described below can be combined in various ways to form multiple variations of the invention. Thus, the present invention is not limited to the following alternative embodiments, but is only limited by the claims and their equivalents.

Example 1:

the embodiment of the invention provides a multi-line laser radar based on a plurality of lasers, which comprises:

the inner part of the rotor is separated into a transmitting cavity and a receiving cavity; the rotor and the stator are prior art in the field and are not described in detail herein;

FIG. 1 is a schematic illustration of a carrier and laser according to an embodiment of the present invention, as shown in FIG. 1;

only one carrier 1 for carrying a plurality of lasers; the carrier is arranged in the emission cavity;

a plurality of lasers 11, for example 20, 40, the specific number corresponding to the number of lines of the laser radar; the lasers are fixed on the carrier body from top to bottom and are collinear;

a light collimation device, such as a collimation lens, and the projection point of the laser on the carrier on a vertical plane 21 including the main axis of the light collimation device has a density distribution in the up-down direction, that is, the up-down distribution of the collinear laser has a density, such as a density in the middle part and a density in the upper part and a density in the lower part; the detection light emitted by the laser passes through the light collimation device and then irradiates on external objects such as the ground, pedestrians, bicycles, bus stop boards, automobiles and the like; the light collimating device is disposed within the emission cavity;

a light receiving device, such as a focusing lens (group), through which the reflected light of the detection light on the external object passes and is received by a detector;

the number of the detectors is the same as that of the lasers, and the detectors and the lasers are symmetrically arranged relative to a middle vertical plane of a central connecting line of the light collimation device and the light receiving device; the probe is disposed within the receiving cavity.

The working process of the multi-line laser radar is as follows:

the multiple lasers emit multiple beams of laser, such as No. 1 laser, and the detection light is collimated by the light collimating device and then emitted to an external object, wherein the density of the central laser beams (horizontal and near horizontal) is high, and the vertical angular resolution is improved;

the reflected light of the detection light on the external object is converged on the detector through the light receiving device, for example, the detection light emitted by the No. 1 laser is converged on the No. 1 detector after being reflected by the external object and passing through the receiving device;

the analysis device processes the electrical signal transmitted by the detector to detect an external object, such as an obstacle.

Example 2:

the embodiment of the invention discloses a multi-line laser radar based on a plurality of lasers, which is different from the embodiment 1 in that:

the plurality of lasers are not all partially collinear, for example, most of the lasers are vertically arranged and collinear, the intervals are equal, and a small part of the lasers are vertically arranged and collinear, and the intervals are equal; the most part of the lasers and the small part of the lasers are staggered in the horizontal direction, so that the projection points of the small part of the lasers on a vertical plane including the main shaft of the optical collimating device are positioned between the projection points of the most part of the lasers on the vertical plane, the projection points have density distribution, the beam density of the laser emergent beams in the horizontal direction and nearby is improved, and the vertical angular resolution is correspondingly improved.

Example 3:

figure 2 schematically illustrates a schematic diagram of a multiline lidar based on multiple lasers according to an embodiment of the invention, as shown in figure 2, comprising:

a rotor comprising an inner chamber 8 and an outer chamber 7, the interior of the inner chamber 8 being separated into a transmitting chamber and a receiving chamber, such as by a partition 91; the rotor and the stator are prior art in the field and are not described in detail herein;

the emission cavity is internally provided with:

FIG. 3 schematically illustrates a schematic structural diagram of a laser and a carrier according to an embodiment of the invention, as shown in FIG. 3;

a plurality of carriers 1, such as 5, each of which is vertically fixed in the emission cavity for carrying a plurality of lasers; a plurality of supporting bodies 1 are distributed at intervals in the horizontal direction;

a plurality of lasers 11, for example 40, the specific number corresponding to the number of lines of the lidar; the laser is fixed on the bearing body from top to bottom; for example, a plurality of lasers are fixed on each carrier body and are collinear;

a light collimation device, such as a collimation lens, and the projection point of the laser on the carrier on a vertical plane 21 comprising the main axis of the light collimation device has density distribution in the up-down direction, such as density of the middle part and density of the upper part and the lower part; the detection light emitted by the laser passes through the light collimation device and then irradiates on external objects such as the ground, pedestrians, bicycles, bus stop boards, automobiles and the like; the light collimating device is disposed within the emission cavity;

the first reflecting mirror 61, an included angle between the first reflecting mirror 61 and the detection light emitted by the laser 11 is an acute angle, that is, the first reflecting mirror 61 is obliquely arranged relative to the supporting body;

a second reflecting mirror 62, which reflects the detection light sequentially by the first reflecting mirror 61 and the second reflecting mirror 62 and passes through the light exit device 2;

a light emitting device 2, such as a collimating lens (group), through which the detection light emitted by the laser 1 passes and then irradiates an external object 3;

a filter device 6, such as an optical filter, where the filter device 6 is disposed outside the inner cavity, and is used for filtering ambient light and transmitting reflected light of the detection light on the external object 3, and is disposed on the reflected light path and upstream of the light receiving device 4;

the receiving cavity is internally provided with:

a light receiving device 4, such as a focusing lens (group), through which reflected light of the detection light on the external object 3 passes and is received by a detector 51;

a third reflector 63, an included angle between the third reflector 63 and the main axis of the light receiving device 4 is an acute angle;

a fourth mirror 64, the reflected light passing through the light receiving device 4 is reflected by the third mirror 63 and the fourth mirror 64 in sequence and then received by the detector 51;

the detectors 51 are fixed on the circuit board 5, the number of the detectors is the same as that of the lasers, and the detectors and the lasers are symmetrically arranged relative to a middle vertical plane of a central connecting line of the light collimation device and the light receiving device; the probe is disposed within the receiving cavity.

The working process of the multi-line laser radar is as follows:

a plurality of lasers 1 emit a plurality of beams of laser light, such as No. 1 laser light, and the laser light, as a detection light, sequentially enters the light emitting device 2 through the first reflecting mirror 61 and the second reflecting mirror 62, and is collimated by the light emitting device 2 and then enters the external object 3;

the reflected light of the detection light on the external object 3 is converged by the light receiving device 4, and then is reflected to the detector 51 by the third reflector 63 and the fourth reflector 64 in sequence, for example, the detection light emitted by the No. 1 laser is converged on the No. 1 detector after being reflected by the external object 3 and passing through the receiving device;

the analyzing device processes the electrical signal transmitted from the detector 51 to detect the foreign object 3, such as an obstacle.

Example 4:

the embodiment of the invention discloses a multi-line laser radar based on a plurality of lasers, which is different from the embodiment 2 in that:

fig. 4 is a schematic diagram of a carrier and lasers according to an embodiment of the present invention, and as shown in fig. 4, there are a plurality of carriers 1, such as 8, each of which has a plurality of lasers 11, such as 5, disposed thereon, and the distances between the lasers are equal;

fixing plates 12, e.g., 5, the fixing plates 12 being vertically disposed in the emission chamber and spaced apart from each other in a horizontal direction; the supporting bodies 1 are fixed on the side parts of the fixing plates, the number of the supporting bodies 1 fixed on each fixing plate 12 is different, for example, from left to right, 2, 1, 2, 1 supporting bodies are respectively fixed on each fixing plate;

the projection points of the laser 11 on the vertical plane 21 including the principal axis of the light collimating device have a density distribution in the up-down direction, such as a density in the middle part and a density in the upper part and a density in the lower part, so that a plurality of detection lights emitted by the laser have a density in the horizontal line and nearby and a density in the other directions.

Fig. 5 schematically shows a schematic structural diagram of a scanning device for a multiline lidar according to an embodiment of the present invention, as shown in fig. 5, the scanning device including:

a central shaft 92 having a recess therein; the middle shaft is divided into a thicker part, a transition part and a thinner part;

the top end of the middle shaft is fixed on the fixed seat 97; for example, the fixed seat is a circular groove with a bulge at the center, and the top end of the thinner part is fixed on the bulge;

a motor 94, which is arranged at the lower part of the fixed seat and is adjacent to the fixed seat, and the stator of the motor is sleeved at the outer edge of the upper part of the middle shaft between the fixed seat and the base, such as the outer edge of the thinner part; a rotor of the motor rotates around the middle shaft, and a power line of the motor is laid in the groove;

the bottom end of the rotor is connected with a rotating cavity through the coupler 95, so that the rotor drives the rotating cavity to rotate around the middle shaft;

a rotating cavity 96 fixed by a bearing at the outer edge of the middle shaft at the lower part of the stator, such as the outer edge of the transition part, and distributed at the lower part of the motor and the periphery of the motor along the radial direction of the middle shaft, but not at the upper part of the motor; the interior of the rotating cavity is separated into a transmitting cavity and a receiving cavity;

the bottom end of the middle shaft is fixed on the base 92, if the base is a circular groove with a bulge in the center, the thicker part of the middle shaft is fixed on the bulge of the base;

a wireless power transmission module, the wireless power transmission module comprising:

the transmitting part is fixed on the middle shaft;

a receiving portion 71, fixedly connected to the rotation chamber and rotatable about the central axis;

an upper circuit board 72 disposed at a bottom end of the rotation chamber; the wireless power transmission module supplies power to the upper circuit board;

a lower circuit board 73 fixed on the base, wherein the distance between the upper circuit board and the lower circuit board is greater than zero;

a rotary encoder 74 disposed at a bottom end of the rotation chamber, the distance from the rotary encoder to the base being greater than zero.

Example 5:

an example of an application of a multi-line lidar based on multiple lasers according to embodiment 2 of the present invention.

In this application example, there are 16 lasers, i.e. 16 line lidar; the 16 lasers are arranged on only one carrier in 2 rows and are positioned on a focal plane of the optical collimating device, wherein the No. 1-10 lasers and the No. 11-16 lasers are vertically arranged at equal intervals and are collinear, and the intervals are d respectively; the No. 11-16 lasers are arranged on the side parts of the No. 1-10 lasers, wherein the distances from the No. 11 laser to the No. 3 and the No. 4 lasers are equal, and the distances from the No. 16 laser to the No. 8 and the No. 9 lasers are equal. Thus, the distance between the No. 1-3 and No. 9-10 lasers is d, and the distance between the No. 3-9 and No. 11-16 lasers in the vertical direction is d

Example 6:

an example of an application of a multi-line lidar based on multiple lasers according to embodiment 4 of the present invention.

In this application example, there are 40 lasers, i.e. 40 line lidar; the device is provided with 8 bearing bodies and 5 fixing plates 12 which are vertically arranged, wherein the fixing plates 12 are clamped in grooves 81 in the up-down direction and are fixed by using glue 82, as shown in figure 6; from left to right, each fixed plate is provided with 2, 1, 2 and 1 bearing bodies, each bearing body is provided with 5 lasers in an up-down collinear manner, and the distance is d; the projection points of the 40 lasers on the vertical plane including the main axis of the optical collimating device have density distribution in the up-down direction, such as the density of the middle part, and the distance (i.e. height difference) in the up-down direction is

The upper part and the lower part are sparse, and the distance (namely the height difference) in the up-down direction is d.

The 40-line vehicle-mounted laser radar has a vertical field range of-14 degrees to +5 degrees (not dividing the field of view vertically), wherein the vertical angle in the range of +3 degrees to +5 degrees is resolved into 1 degree (corresponding to the 1 st-3 line laser beams, from bottom to top), the vertical angle in the range of-7 degrees to +3 degrees is resolved into an encrypted subsection, the vertical angle is resolved into 1/3 degrees (corresponding to the 3 rd-33 line laser beams), and the vertical angle in the range of-14 degrees to-7 degrees is resolved into 1 degree (corresponding to the 33 th-40 line laser beams). By increasing the density of the central laser beam (horizontal and near horizontal) it is ensured that information of distant pedestrians, vehicles, etc. can be obtained as much as possible.

Claims

1. A multiline lidar comprising a rotor, a stator and a plurality of lasers; the method is characterized in that: the detection light emitted by each laser is reflected by the obstacle and then converged on the corresponding detector after passing through the receiving device, and the multi-line laser radar further comprises:

the carrier is provided with the plurality of lasers; the lasers are arranged on the supporting body in n rows, and n is more than or equal to 2; the bearing body is arranged in the rotor;

a light collimating device;

the detection light beams emitted by the laser are driven by the motor to scan around the central axis to generate scanning lines which are distributed densely in the vertical direction so as to obtain the information of the obstacles in the central field of view as much as possible;

the light collimating device is disposed within the rotor;

the wiring harness of the multi-line laser radar is more than or equal to 16.

2. Multiline lidar according to claim 1, wherein: the vertical plane is parallel to the central axis.

3. Multiline lidar according to claim 1, wherein: the projection points are distributed from top to bottom in a sparse-dense-sparse way.

4. Multiline lidar according to claim 1, wherein: in the vertical direction, in the laser in the middle part, the projection point of the part of the lasers on the vertical plane is between the projection points of other collinear adjacent lasers on the vertical plane, and the part of the lasers and the adjacent lasers are non-collinear.

5. Multiline lidar according to claim 1, wherein: the laser is in the focal plane of the optical collimating means.

6. Multiline lidar according to claim 1, wherein: the number of the bearing bodies is at least two, and each bearing body is provided with at least two lasers.

7. Multiline lidar according to claim 6, wherein: in the direction perpendicular to the vertical plane, the supporting bodies are distributed at intervals.

8. Multiline lidar according to claim 7, wherein: in the middle carrier, the projection point of the laser on the carrier on the vertical plane is between the projection points of the adjacent lasers on the other same carrier on the vertical plane.

9. Multiline lidar according to claim 8, wherein: at least two projection points are arranged between projection points of adjacent lasers on the same bearing body on the vertical plane, and the at least two projection points are projection points of the lasers on other different bearing bodies.

10. Multiline lidar according to claim 1, wherein: the multiline lidar further comprising:

the light receiving device is used for collecting the external reflected light of the measuring light emitted by the laser after passing through the light collimating device;

a photodetector that receives the reflected light after passing through the light receiving device; the number of the photoelectric detectors is the same as that of the lasers, the arrangement of the photoelectric detectors and the arrangement of the lasers are symmetrical about a median vertical plane of a central connecting line of the light collimation device and the light receiving device, and a main shaft of the light collimation device is parallel to the median vertical plane.

11. Multiline lidar according to claim 10, wherein: the main shaft is perpendicular to the central connecting line.

12. A method of detection using a multiline lidar according to any of claims 1-11.