CN113552554B

CN113552554B - Multi-line laser radar and method for detecting by using multi-line laser radar

Info

Publication number: CN113552554B
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: 2023-04-25
Anticipated expiration: 2037-06-19
Also published as: CN113552554A; CN107121683A; CN107121683B; CN113447910A; CN113447910B

Abstract

The invention provides a multi-line laser radar, which comprises a rotor, a stator and a plurality of lasers, wherein the rotor is connected with the stator; the method is characterized in that: after being reflected by the obstacle, the detection light emitted by each laser is converged on the corresponding detector after passing through the receiving device, and the multi-line laser radar further comprises: a carrier body on which the plurality of lasers are arranged; 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 collimation device; the detection light beams emitted by the laser device are driven by the motor to have density distribution in the up-down direction of scanning lines generated by scanning around a central axis, so that information of obstacles in a central view field can be obtained as much as possible; the light collimation device is arranged in 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 angle resolution, high horizontal angle 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 the invention patent application with the application number of 201710463616.6 and the invention name of multi-line laser radar based on multiple lasers, which is filed on the date of 2017, 6 and 19.

Technical Field

The invention relates to a laser radar, in particular to a multi-line laser radar and a method for detecting by using the multi-line laser radar.

Background

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

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

In addition, if all angles of view are equally divided according to the angle division scheme of the current market products, more lines are required to achieve higher vertical resolution, which means higher cost, larger volume and lower reliability stability. Because of the limited data capacity of the ethernet and the processing speed of the vehicle CPU, a higher line number of lidars (such as Velodyne) cannot combine both high horizontal angular resolution and high scanning frequency.

The number of lines is reduced for cost reduction reasons, and the angular interval is too large, so that the target cannot be distinguished in a short distance range (such as 40 meters), for example, 16 lines are required at a total vertical field angle of 32 degrees and at a 2 degree interval (vertical resolution), and a pedestrian is easily missed at a distance of 40m, wherein the distance between the laser beams is about 1.4 m.

Disclosure of Invention

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

The invention aims at realizing the following technical scheme:

a multi-line lidar based on a plurality of lasers, the multi-line lidar comprising a rotor and a stator; the multi-line lidar further comprises:

a carrier body on which a plurality of lasers are arranged; the bearing body is arranged in the rotor;

the laser on the supporting body is provided with a sparse and dense distribution in the up-down direction of projection points on a vertical plane comprising the main shaft of the light collimation device; the light collimating device is disposed within the rotor.

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

1. according to the invention, through the density arrangement of the lasers, when the laser beams are unevenly distributed and designed in a lower wire harness, 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) to be identified in the running process of the vehicle are generally gathered on a horizontal line and near the ground, so that the density of a central laser beam (horizontal and near the horizontal) is enhanced, and the non-uniform laser beam is distributed more scientifically and reasonably in a real traffic environment;

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

4. the invention adopts a coaxial (motor, rotating cavity, upper circuit board and the like all rotate around the center 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 overhead (the motor is rotatably fixed on the outer edge of the upper part of the center shaft, the rotating cavity is positioned at the lower part of the motor and along the radial outer edge of the center shaft, and is not on the upper part of the motor), so that the distance between the upper circuit board and the lower circuit board is very short, the communication is convenient, and the overhaul of a transmission system is also very convenient.

Drawings

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

fig. 1 is a schematic view of a carrier and a laser according to embodiment 1 of the present invention;

fig. 2 is a schematic diagram of a multi-line lidar based on multiple lasers according to embodiment 3 of the present invention;

fig. 3 is a schematic view of the structure of the carrier and the laser according to embodiment 3 of the present invention;

fig. 4 is a schematic view of the structure of the carrier and the laser according to embodiment 4 of the present invention;

fig. 5 is a schematic view of a scanning device in a multi-line lidar according to embodiment 4 of the present invention;

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

Detailed Description

Figures 1-6 and the following description depict alternative embodiments of the invention to teach those skilled in the art how to make and reproduce the invention. In order to teach the technical solution of the present invention, some conventional aspects have been simplified or omitted. Those skilled in the art will appreciate variations or alternatives derived from these embodiments that fall 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 invention is not limited to the following alternative embodiments, but only 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:

a rotor and a stator, wherein the interior of the rotor is isolated into a transmitting cavity and a receiving cavity; the rotor and stator are prior art in the art and are not described in detail herein;

fig. 1 schematically shows a schematic diagram of the carrier and laser of an embodiment of the invention, as shown in fig. 1;

there is only one carrier 1 for carrying a plurality of lasers; the supporting body is arranged in the transmitting cavity;

a plurality of lasers 11, such as 20 and 40, the specific number corresponds to the line number of the laser radar; the lasers are fixed on the supporting body from top to bottom and are collinear;

the projection points of the lasers on the carrier body on the vertical plane 21 comprising the main axis of the light collimating device are distributed in a sparse and dense way in the up-down direction, namely the upper-down distribution of the collinear lasers is distributed in a sparse way, such as the middle part is dense, and the upper part and the lower part are sparse; the detection light emitted by the laser passes through the light collimation device and irradiates on external objects such as ground, pedestrians, bicycles, bus stop boards, automobiles and the like; the light collimation device is arranged in the emission cavity;

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

the number of the detectors is the same as that of the lasers, and the detectors and the lasers are symmetrically arranged on the middles of central connecting lines of the light collimation devices and the light receiving devices; the detector is disposed within the receiving cavity.

The working process of the multi-line laser radar comprises the following steps:

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

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 reflected by the external object and then converged on the No. 1 detector through the receiving device;

the analysis device processes the electrical signal transmitted from the detector to detect foreign objects, such as obstacles.

Example 2:

the multi-line laser radar based on multiple lasers in the embodiment of the invention is different from the embodiment 1 in that:

the lasers are not all collinear, such as most of the lasers are vertically arranged and collinear, the spacing is equal, and the other part of the lasers are vertically arranged and collinear, and the spacing is equal; the large part of lasers and the small part of lasers are staggered in the horizontal direction, so that the projection points of the small part of lasers on the vertical plane comprising the main shaft of the light collimation device are positioned between the projection points of the large part of lasers on the vertical plane, the projection points are distributed in a sparse and dense mode, the beam density of the outgoing beam of the lasers in the horizontal direction and nearby is improved, and the vertical angle resolution is correspondingly improved.

Example 3:

fig. 2 schematically shows a schematic structural diagram of a multi-line lidar based on a plurality of lasers according to an embodiment of the present invention, as shown in fig. 2, the multi-line lidar comprising:

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

the emission cavity is internally provided with:

fig. 3 schematically shows a schematic diagram of the laser and carrier of an embodiment of the invention, as shown in fig. 3;

a plurality of carriers 1, e.g. 5, each vertically fixed within the emission cavity for carrying a plurality of lasers; the plurality of carriers 1 are distributed at intervals in the horizontal direction;

a plurality of lasers 11, such as 40, the specific number corresponds to the line number of the laser radar; the laser is fixed on the supporting body from top to bottom; a plurality of lasers are fixed on each carrier and are collinear;

light collimating means, such as a collimating lens, the projected spots of the laser on the carrier on a vertical plane 21 comprising the principal axis of the light collimating means having a dense distribution in the up-down direction, such as a dense middle portion, a dense upper portion and a dense lower portion; the detection light emitted by the laser passes through the light collimation device and irradiates on external objects such as ground, pedestrians, bicycles, bus stop boards, automobiles and the like; the light collimation device is arranged in 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 carrier;

a second reflecting mirror 62, the detection light passes through the light emitting device 2 after being reflected by the first reflecting mirror 61 and the second reflecting mirror 62 in order;

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

a filter device 6, such as a light filter, the filter device 6 is disposed outside the inner cavity, and is configured to filter out ambient light and transmit reflected light of the detection light on the foreign object 3, and is disposed on the light path of the reflected light 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), the reflected light of the detection light on the foreign object 3 being received by the detector 51 after passing through the light receiving device 4;

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

a fourth reflecting mirror 64, the reflected light passing through the light receiving device 4 is received by the detector 51 after being reflected by the third reflecting mirror 63 and the fourth reflecting mirror 64 in order;

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 about the middle vertical plane of the central connecting line of the light collimation device and the light receiving device; the detector is disposed within the receiving cavity.

the multiple lasers 1 emit multiple laser beams, for example, a number 1 laser emits detection light, the detection light is sequentially incident on the light emitting device 2 through the first reflecting mirror 61 and the second reflecting mirror 62, and the detection light is collimated by the light emitting device 2 and then is emitted on 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 reflected to the detector 51 by the third reflecting mirror 63 and the fourth reflecting mirror 64 in sequence, for example, the detection light emitted by the No. 1 laser is reflected by the external object 3 and converged on the No. 1 detector after 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 multi-line laser radar based on multiple lasers in the embodiment of the invention is different from the embodiment 2 in that:

fig. 4 schematically shows a schematic diagram of the carrier and the lasers according to an embodiment of the present invention, as shown in fig. 4, a plurality of carriers 1, e.g. 8, each carrier being provided with a plurality of lasers 11, e.g. 5, the distance between the lasers being equal;

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

the projected spots of the laser 11 on the vertical plane 21 including the principal axis of the light collimating device have a dense distribution in the up-down direction, such as dense in the middle, dense in the upper and lower parts, so that the beams of the multiple detection light emitted from the laser are dense in the horizontal and nearby directions, and sparse in the other directions.

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

a bottom bracket 92 having a recess therein; the middle shaft is divided into a thicker part, a transitional part and a thinner part;

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

the motor 94 is arranged at the lower part of the fixed seat and faces the fixed seat, and the stator of the motor is sleeved on 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; the rotor of the motor rotates around the central shaft, and a power line of the motor is paved in the groove;

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

a rotating chamber 96 fixed to the outer edge of the central shaft at the lower part of the stator through a bearing, such as the outer edge of a transition part, the rotating chamber being distributed at the lower part of the motor and the outer periphery of the motor along the radial direction of the central shaft, not at the upper part of the motor; the interior of the rotating cavity is isolated into a transmitting cavity and a receiving cavity;

the base 92, the bottom end of the central shaft is fixed on the base, for example, the base is a round groove with a bulge in the center, and the thicker part is fixed on the bulge of the base;

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

the transmitting part is fixed on the middle shaft;

a receiving portion 71 fixedly connected to the rotation chamber and rotated 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 for the upper circuit board;

a lower circuit board 73 fixed to the base, a distance between the upper circuit board and the lower circuit board being greater than zero;

a rotary encoder 74 is disposed at the bottom end of the rotating chamber, the rotary encoder being spaced from the base by a distance greater than zero.

Example 5:

an application example 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, namely 16-line lidar; the 16 lasers are arranged on only one carrier in 2 rows and are positioned on the focal plane of the light collimation device, wherein the 1 st to 10 th lasers and the 11 th to 16 th lasers are vertically arranged at equal intervals and are collinear, and the intervals are d respectively; the 11 th to 16 th lasers are arranged on the side parts of the 1 st to 10 th lasers, wherein the distances from the 11 th laser to the 3 rd and 4 th lasers are equal, and the distances from the 16 th laser to the 8 th and 9 th lasers are equal. Thus, the distance between the lasers of the 1 st to 3 th and the 9 th to 10 th is d, and the distance between the lasers of the 3 rd to 9 th and the 11 th to 16 th in the vertical direction is

Example 6:

an application example 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, namely 40 line lidar; the fixing plate 12 is clamped in a groove 81 in the up-down direction and is fixed by using glue 82, as shown in fig. 6; 2, 1, 2 and 1 supporting bodies are arranged on each fixed plate from left to right, 5 lasers are arranged on each supporting body in an up-down collineation way, and the distance is d; the projection points of 40 lasers on the vertical plane including the main axis of the light collimation device have a dense distribution in the up-down direction, such as middle part is dense, and the distance (i.e. height difference) in the up-down direction is

The upper and lower portions are thinned, and the distance (i.e., the height difference) in the up-down direction is d.

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

Claims

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

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

a light collimation device;

the detection light beams emitted by the lasers are driven by the motor to scan around the central axis to generate scanning point clouds which are distributed in a sparse and dense mode in the up-down direction, so that information of obstacles in the central view field can be obtained as much as possible;

the light collimation device is arranged in the rotor;

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

2. The multi-line lidar of claim 1, wherein: the vertical plane is parallel to the central axis.

3. The multi-line lidar of claim 1, wherein: the projection points are distributed in a sparse-dense-sparse mode from top to bottom.

4. The multi-line lidar of claim 1, wherein: in the vertical direction, among the lasers in the middle part, the projection points of part of the lasers on the vertical plane are positioned between the projection points of other collinear adjacent lasers on the vertical plane, and the part of the lasers and the adjacent lasers are not collinear.

5. The multi-line lidar of claim 1, wherein: the laser is at the focal plane of the light collimating device.

6. The multi-line lidar of claim 1, wherein: the number of the supporting bodies is at least two, and at least two lasers are arranged on each supporting body.

7. The multi-line lidar of claim 6, wherein: the carriers are spaced apart in a direction perpendicular to the vertical plane.

8. The multi-line lidar of claim 7, wherein: in the vertical direction, in the carrier in the middle part, the projection points of the lasers on the carrier on the vertical plane are located between the projection points of adjacent lasers on other identical carriers on the vertical plane.

9. The multi-line lidar of claim 8, wherein: adjacent lasers on the same carrier have at least two proxels between proxels on the vertical plane, the at least two proxels being proxels of lasers on other different carriers.

10. The multi-line lidar of claim 1, wherein: the multi-line lidar further comprises:

a light receiving device, wherein reflected light of the measuring light emitted by the laser after passing through the light collimating device in the outside is collected by the light receiving 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 with respect to a central vertical plane of a central connecting line of the light collimating device and the light receiving device, and a main shaft of the light collimating device is parallel to the central vertical plane.

11. The multi-line lidar of claim 10, wherein: the main shaft is perpendicular to the central connecting line.

12. A method of detection using a multi-line lidar as claimed in any of claims 1 to 11.