Laser radar detection method, laser radar, and computer storage medium

Abstract

The application provides a detection method of a laser radar, the laser radar comprising a scanning device, the detection method comprising: S101: emitting a first group of detection beams; S102: reflecting the first group of detection beams to the outside of the laser radar by the scanning device, and receiving a first group of echoes of the first group of detection beams on an obstacle, to obtain a first point cloud; S103: emitting a second group of detection beams; and S104: reflecting the second group of detection beams to the outside of the laser radar by the scanning device, and receiving a second group of echoes of the second group of detection beams on the obstacle, to obtain a second point cloud; wherein the first point cloud and the second point cloud correspond to different detection distances respectively. The application effectively solves the problem of the ranging blind area in the laser radar of the coaxial transmitting-receiving system through time-sharing detection, control of the light intensity of the laser and the bias voltage of the detector, and point cloud fusion, and can freely adjust the resolution of different detection ranges.

Description

[0001] This application is a divisional application of Chinese invention patent application filed on November 22, 2021, with application number 202111388089.X and invention title "Detection Method of LiDAR, LiDAR and Computer Storage Medium". Technical Field

[0002] This invention relates to the field of photoelectric detection, and more particularly to a detection method for lidar, lidar, and computer storage medium. Background Technology

[0003] LiDAR (Light Detection and Ranging) is a radar system that uses laser beams to detect the position, velocity, and other characteristics of targets. Due to its advantages such as high resolution, good concealment, strong resistance to active interference, small size, and light weight, LiDAR is widely used in fields such as autonomous driving. Specifically, LiDAR emits a detection beam into the surrounding three-dimensional environment. The detection beam is reflected by obstacles in the three-dimensional environment, forming an echo. The echo is received and converted into an electrical signal. The signal processing unit in the LiDAR receives the electrical signal and calculates the characteristic information of the obstacle, such as distance, azimuth, and reflectivity.

[0004] Figure 1 A schematic diagram of a coaxial transceiver system for a lidar is shown. The lidar includes a transmitting unit and a receiving unit. The detection beam L emitted by the transmitting unit passes through a collimating component and a beam splitting component, and is finally reflected by a scanning component to the outside of the lidar. The echo L' reflected by an obstacle passes through the scanning component, beam splitting component, and converging component before being received by the receiving unit. Figure 1 It is evident that the transmitting and receiving optical paths share common components. Because the internal transmitting and receiving optical paths cannot be completely isolated, stray light will exist within the lidar. For example, part of the detection beam emitted by the laser in the transmitting unit may strike the detector in the receiving unit, forming stray light. This stray light will reduce the lidar's short-range detection capability and create a near-range blind zone.

[0005] Figure 2 The diagram illustrates how stray light from a lidar sensor affects close-range detection. For example... Figure 2 As shown, when stray light is too strong, the echo signal generated by the stray light superimposes with the target echo, making it impossible to identify the target. That is, during the stray light duration (t1-t2), if there is a target echo, the target echo will be masked by the stray light echo and cannot be distinguished. At the same time, the detector's baseline will be temporarily raised, and the lidar's detection performance will weaken for a period of time, meaning the echo waveform of near-range targets will be weaker before the detection capability is restored. During this period, the lidar cannot identify the echo signal, thus creating a near-range blind zone.

[0006] The content of the background section only discloses the technology known to the inventors and does not necessarily represent the prior art in this field. Summary of the Invention

[0007] In existing coaxial LiDAR transceiver systems, stray light occurs because the internal transmitting and receiving optical paths cannot be completely isolated. This stray light reduces short-range detection capability, resulting in a short-range blind zone for the LiDAR. Therefore, this invention relates to a LiDAR detection method to solve the problem of the short-range blind zone in LiDAR. The LiDAR includes a scanning device, and the detection method includes:

[0008] S101: Firing the first set of probe beams;

[0009] S102: The scanning device reflects the first set of detection beams to the outside of the lidar and receives the first set of echoes of the first set of detection beams on the obstacle to obtain the first point cloud;

[0010] S103: Fire the second set of probe beams; and

[0011] S104: The scanning device reflects the second set of detection beams to the outside of the lidar and receives the second set of echoes of the second set of detection beams on the obstacle to obtain the second point cloud;

[0012] The first point cloud and the second point cloud correspond to different detection ranges.

[0013] According to one aspect of the invention, the scanning device includes at least one first reflective surface and at least one second reflective surface, step S102 includes reflecting the first set of detection beams to the outside of the lidar through the first reflective surface and receiving the first set of echoes, and step S104 includes reflecting the second set of detection beams to the outside of the lidar through the second reflective surface and receiving the second set of echoes.

[0014] According to one aspect of the invention, the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface.

[0015] According to one aspect of the invention, the ratio of the effective reflective areas of the first reflective surface and the second reflective surface is determined based on the ratio of the detection ranges corresponding to the first point cloud and the second point cloud.

[0016] According to one aspect of the present invention, step S102 includes: controlling the scanning device to rotate at a first rotational speed; step S104 includes: controlling the scanning device to rotate at a second rotational speed.

[0017] According to one aspect of the invention, the method further includes: adjusting the first rotation speed and / or the second rotation speed according to the detection scene or resolution of the lidar.

[0018] According to one aspect of the present invention, the lidar further includes an optical emitting device, wherein step S101 includes: controlling the optical emitting device to emit a first set of detection beams at a first power; and step S103 includes: controlling the optical emitting device to emit a second set of detection beams at a second power, wherein the first power is greater than the second power.

[0019] According to one aspect of the invention, the second power is 1%-10% of the first power.

[0020] According to one aspect of the invention, the method further includes: dynamically adjusting the emission repetition rate of the first set of detection beams and / or the emission repetition rate of the second set of detection beams based on the detection results.

[0021] According to one aspect of the invention, the detection results include: the area where the obstacle is located and / or the region of interest.

[0022] According to one aspect of the present invention, the lidar further includes an optical receiving device, wherein step S102 includes: applying a first bias voltage to the optical receiving device; and step S104 includes: applying a second bias voltage to the optical receiving device; wherein the detection performance of the optical receiving device under the first bias voltage is higher than the detection performance under the second bias voltage.

[0023] According to one aspect of the invention, the method further includes adjusting the first bias voltage and / or the second bias voltage based on one or more of the intensity of the first set of detection beams, the intensity of the second set of detection beams, the obstacle distance, the obstacle reflectivity, and the maximum detection distance.

[0024] According to one aspect of the present invention, the scanning device includes a plurality of first reflective surfaces and a plurality of second reflective surfaces, and the detection method further includes: fusing at least two of a plurality of point clouds acquired corresponding to the plurality of first reflective surfaces into a first point cloud, and fusing at least two of a plurality of point clouds acquired corresponding to the plurality of second reflective surfaces into a second point cloud.

[0025] According to one aspect of the invention, it further includes:

[0026] The first point cloud and the second point cloud are fused to obtain a frame of point cloud within the detection range of the lidar.

[0027] According to one aspect of the invention, the method further includes: synchronizing the first point cloud and the second point cloud in time based on the motion information of the lidar, and then fusing them.

[0028] According to one aspect of the invention, the method further includes: selecting points from the first point cloud that correspond to points outside the detection range of the second point cloud and fusing them with the second point cloud.

[0029] According to one aspect of the invention, the method further includes: fusing points in the first point cloud that correspond to the detection range of the second point cloud with the second point cloud.

[0030] The present invention also relates to a computer storage medium including computer executable instructions stored thereon, which, when executed by a processor, implement the detection method as described in any one of claims 1-17.

[0031] The present invention also relates to a lidar, comprising:

[0032] An optical emitting device includes at least one laser configured to emit probe beams separately;

[0033] A light receiving device includes at least one detector configured to receive the echoes of the detection beam on an obstacle, respectively.

[0034] The scanning device is configured to reflect a first set of detection beams emitted by the light emitting device to the outside of the lidar, and to receive a first set of echoes of the first set of detection beams on an obstacle; it is also configured to reflect a second set of detection beams emitted by the light emitting device to the outside of the lidar, and to receive a second set of echoes of the second set of detection beams on an obstacle.

[0035] The processing unit, coupled to the optical emitting device and the optical receiving device, is configured to acquire a first point cloud based on the first set of echoes and acquire a second point cloud based on the second set of echoes.

[0036] The first point cloud and the second point cloud correspond to different detection ranges.

[0037] According to one aspect of the invention, the scanning device includes at least one first reflective surface and at least one second reflective surface, wherein the first reflective surface reflects the first set of detection beams to the outside of the lidar and receives the first set of echoes, and the second reflective surface reflects the second set of detection beams to the outside of the lidar and receives the second set of echoes.

[0038] According to one aspect of the invention, the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface.

[0039] According to one aspect of the invention, the processing unit is configured to perform the detection method described above to acquire a first point cloud and a second point cloud and fuse them into a single frame of point cloud.

[0040] The technical effects of this invention can be summarized as follows:

[0041] (1) Obtain point clouds from different detection ranges, and fuse point clouds from different detection ranges based on post-processing algorithms and combined with the motion information of lidar to solve the problem of near-range blind spots.

[0042] (2) Further, by controlling the light intensity of the laser and the bias voltage of the detector, stray light is suppressed to avoid the problem of being unable to identify the echo of a nearby target;

[0043] (3) Further, by adjusting the motor speed and the transmission repetition rate, the resolution of different detection ranges can be freely adjusted to change the resolution of a specific area. Attached Figure Description

[0044] The accompanying drawings, which form part of this disclosure, are used to provide a further understanding of this disclosure. The illustrative embodiments of this disclosure and their descriptions are used to explain this disclosure and do not constitute an undue limitation of this disclosure. In the drawings:

[0045] Figure 1 A schematic diagram of a lidar system with a coaxial transceiver is shown.

[0046] Figure 2 A schematic diagram illustrating the impact of stray light on close-range detection in lidar is shown.

[0047] Figure 3 A flowchart of a lidar detection method according to an embodiment of the present invention is shown;

[0048] Figure 4 A schematic diagram of lidar detection according to an embodiment of the present invention is shown;

[0049] Figure 5A A schematic diagram illustrating detection via a first reflective surface according to an embodiment of the present invention is shown;

[0050] Figure 5B A schematic diagram illustrating detection via a second reflective surface according to an embodiment of the present invention is shown;

[0051] Figure 6 A schematic diagram of the reflecting surface and incident light according to an embodiment of the present invention is shown;

[0052] Figure 7 A schematic diagram of the detection time and power of a four-sided rotating mirror according to an embodiment of the present invention is shown;

[0053] Figure 8A schematic diagram of stray light echo and target echo according to an embodiment of the present invention is shown;

[0054] Figure 9 A schematic diagram of a lidar module according to an embodiment of the present invention is shown. Detailed Implementation

[0055] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0056] In the description of this 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," and "counterclockwise," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0057] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0059] The following disclosure provides many different embodiments or examples for implementing various structures of the invention. To simplify the disclosure, specific examples of components and arrangements are described below. These are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different examples; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. In addition, examples of various specific processes and materials are provided in this invention, but those skilled in the art will recognize the application of other processes and / or the use of other materials.

[0060] Figure 1 A schematic diagram of a coaxial transceiver system for lidar is shown. A coaxial transceiver system for lidar typically includes beam-splitting components, such as polarizing beam splitters, pinhole mirrors, and small mirrors.

[0061] When a polarizing beam splitter is used, the detection beam emitted by the laser array passes through the polarizing beam splitter and the scanner before exiting the lidar. The echo, after being reflected by an obstacle, passes through the scanner and the polarizing beam splitter again before being incident on the detector array. The polarizing beam splitter is configured to allow the beam to be transmitted or reflected depending on its polarization direction. For example, for the polarization state of the laser emitted by the laser array, the laser is allowed to be reflected; for the returning echo, it is allowed to be transmitted and incident on the detector array.

[0062] When using a pinhole reflector, the detection beam emitted by the laser array is aligned with the pinhole on the reflector, allowing it to pass through the pinhole and be incident on the positive lens. It then passes through the reflector and scanner before exiting the lidar. The echo of the detection beam, after being reflected by an obstacle, passes through the scanner, reflector, and positive lens before being incident on the edge region of the reflector and reflected onto the detector array.

[0063] When a small reflector is used, the detection beam emitted by the laser array is reflected by the small reflector, and then passes through the positive lens, the reflector, and the scanner before exiting to the outside of the lidar. The echo of the detection beam after being reflected by an obstacle passes through the scanner, the reflector, and the positive lens, and then passes through the edge of the small reflector before entering the detector array.

[0064] In coaxial transceiver systems employing the aforementioned beam splitting components, stray light will be generated inside the lidar. The echo signal generated by the stray light superimposes with the target echo, making it impossible to identify the target and creating a near-range blind zone.

[0065] Therefore, this invention proposes a detection method for a lidar, the lidar including a scanning device, the detection method comprising: S101: emitting a first set of detection beams; S102: reflecting the first set of detection beams to the outside of the lidar through the scanning device, and receiving a first set of echoes of the first set of detection beams on an obstacle to obtain a first point cloud; S103: emitting a second set of detection beams; and S104: reflecting the second set of detection beams to the outside of the lidar through the scanning device, and receiving a second set of echoes of the second set of detection beams on an obstacle to obtain a second point cloud; wherein the first point cloud and the second point cloud correspond to different detection ranges.

[0066] This invention proposes to perform detection at different ranges within the system architecture of the scanning device, thereby effectively solving the problem of near-range blind spots in the lidar of the coaxial transceiver system.

[0067] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0068] Figure 3 This invention illustrates a detection method for a lidar 20 according to an embodiment of the present invention. The lidar 20 includes a scanning device 21 (e.g., ...). Figure 4 As shown, the scanning device 21 includes a reflective surface and is rotatable 360 ​​degrees or within a certain angle range. It is used to reflect the detection beam to the outside of the lidar and to receive the echo of the detection beam on an obstacle and reflect it back to the lidar's light receiving device. The specific structure of the scanning device 21 will be described in detail in the preferred embodiment below. First, refer to... Figure 3 The detection method 10 is described in detail.

[0069] In step S101, the first set of probe beams L1 is emitted. Figure 4A schematic diagram of a lidar detection according to an embodiment of the present invention is shown. The lidar 20 further includes a light emitting device 22, which emits a first set of detection beams L1. The light emitting device 22 includes, for example, multiple lasers (e.g., vertical cavity surface-emitting lasers (VCSELs) or edge-emitting lasers (EELs) disposed on the same emitting circuit board. The multiple lasers can be arranged at intervals along the vertical direction to form a one-dimensional linear array; alternatively, at least two one-dimensional linear array laser arrays can be arranged alternately or in a matrix arrangement along the vertical direction to form a two-dimensional surface array, wherein the laser arrays of the one-dimensional linear array are also arranged at intervals along the vertical direction to form a one-dimensional linear array. The lasers in the laser array of a one-dimensional linear array or a two-dimensional planar array emit at time intervals. Specifically, one or more columns of lasers can emit at time intervals simultaneously or along the vertical direction according to a preset time sequence, or a row of lasers can emit at time intervals simultaneously or according to a preset time sequence. This invention does not limit the number, arrangement, or emission sequence of the lasers. The first group of detection beams L1 is a collection of detection beams emitted by multiple lasers, wherein each laser can emit multiple coded detection beams or a single detection beam within the corresponding emission time.

[0070] In step S102, the scanning device 21 reflects the first set of detection beams L1 to the outside of the lidar 20, and receives the first set of echoes L1' of the first set of detection beams L1 on the obstacle to obtain the first point cloud. The lidar 20 also includes a light receiving device 23 and a processing unit ( Figure 4 (Not shown in the image), the light receiving device 23 receives the first set of echoes L1' and converts them into electrical signals. The processing unit can then acquire the first point cloud based on these electrical signals. For example, the first set of detection beams L1 emitted by multiple lasers in the light emitting device 22 is reflected into space by the scanning device 21 as it rotates. This creates multiple sub-scanning fields of view. The first set of detection beams L1 is reflected by obstacles to form the first set of echoes L1'. These echoes L1' are then reflected by the scanning device 21 as it rotates to different angles and received by the light receiving device 23. The processing unit then stitches together the multiple sub-scanning fields of view to form the total detection field of view of the lidar. The collection of point data from the multiple sub-scanning fields of view forms the first point cloud. The light receiving device 23 may include multiple detectors (e.g., SiPM, SPAD, APD, etc. photodetectors) mounted on the same receiving circuit board. These detectors are correspondingly mounted to multiple lasers, and their opening and closing control sequences are synchronized with the corresponding lasers. However, this invention does not limit the number, arrangement, or correspondence between the detectors and the lasers.

[0071] In step S103, a second set of probe beams L2 is emitted. The optical emitting device 22 emits the second set of probe beams L2. The optical emitting device 22 may include, for example, multiple lasers mounted on the same emitting circuit board, operating on the same principle as described above, and will not be repeated here. The second set of probe beams L2 is a collection of probe beams emitted by multiple lasers, wherein each laser can emit multiple coded probe beams within a corresponding emission time, or it can emit a single probe beam.

[0072] In step S104, the scanning device 21 reflects the second set of detection beams L2 to the outside of the lidar 20 and receives the second set of echoes L2' of the second set of detection beams L2 on the obstacle to obtain the second point cloud. The light receiving device 23 receives the second set of echoes L2' and converts them into an electrical signal, which the processing unit uses to obtain the second point cloud. For example, the second set of detection beams L2 emitted by multiple lasers in the light emitting device 22 is reflected into space at different angles by the rotating scanning device 21, forming multiple sub-scanning fields of view. The second set of detection beams L2 is reflected by the obstacle to form the second set of echoes L2', which are then reflected by the rotating scanning device 21 and received by the light receiving device 23. The processing unit stitches together the multiple sub-scanning fields of view to form the total detection field of view of the lidar, where the collection of point data from the multiple sub-scanning fields of view forms the second point cloud.

[0073] In step S101, multiple lasers emit a first set of detection beams L1 (forming one or more beams) in a time-division manner. The scanning device 21 rotates to reflect the first set of detection beams L1 to different detection angles, forming multiple sub-scanning fields of view. These sub-scanning fields of view are then combined to form the total detection field of view of the lidar, completing the detection of the first detection range. In step S103, the multiple lasers repeat the same emission operation. The scanning device 21 rotates to reflect the second set of detection beams L2 emitted by the lasers to different detection angles, forming multiple sub-scanning fields of view. These sub-scanning fields of view are then combined to form the total detection field of view of the lidar, completing the detection of the second detection range. Correspondingly, in steps S102 and S104, the scanning device 21 receives the first set of echoes L1' and the second set of echoes L2', respectively, to obtain the corresponding first point cloud and second point cloud. The first point cloud and the second point cloud correspond to different detection ranges. The different detection ranges refer to the different detection distances of the lidar. For example, the first point cloud corresponds to the first detection range, that is, the range from the lidar 20 to its maximum detection distance; the second point cloud corresponds to the second detection range, that is, the range from the lidar 20 to a preset distance. Specifically, the first point cloud includes all scan points within the range from the lidar 20 to its maximum detection distance, and the second point cloud includes all scan points within the range from the lidar 20 to the preset distance. For example, if the maximum detection distance of the lidar 20 is 200 meters and the preset distance is 50 meters, then the first point cloud corresponds to a detection range of 0-200 meters, and the second point cloud corresponds to a detection range of 0-50 meters.

[0074] The above description describes the process of first emitting the first set of detection beams L1 and then emitting the second set of detection beams L2. However, the present invention is not limited to the above order. It may also be implemented in the order of first emitting the second set of detection beams L2 and then emitting the first set of detection beams L1. All of these are within the scope of the present invention.

[0075] In summary, this invention achieves time-division measurement of different detection ranges through the scanning device 21. Compared to the technical solution of simultaneous long-range and short-range detection, separating long-range and short-range detection allows for adjustment of the lidar control parameters (e.g., adjusting the laser intensity and detector bias voltage) during short-range detection to suppress stray light, thereby solving the short-range blind zone problem. The method for adjusting the lidar control parameters to suppress stray light is further described below through preferred embodiments.

[0076] According to a preferred embodiment of the present invention, the scanning device 21 includes at least one first reflective surface 211 and at least one second reflective surface 212, the step S102 includes: reflecting a first set of detection beams L1 to the outside of the lidar 20 through the first reflective surface 211 and receiving a first set of echoes L1', and the step S104 includes reflecting a second set of detection beams L2 to the outside of the lidar 20 through the second reflective surface 212 and receiving a second set of echoes L2'.

[0077] Continue to refer to Figure 4 The lidar 20 includes a light emitting device 22, a light receiving device 23, and a scanning device 21. The scanning device 21 includes at least one first reflecting surface 211 and at least one second reflecting surface 212. The light emitting device 22 emits a first set of detection beams L1, which are reflected by the first reflecting surface 211 of the scanning device 21 and then emitted to the outside of the lidar 20. As the scanning device 21 rotates, the first reflecting surface 211 stops at multiple angles, causing the first set of detection beams L1 to form multiple sub-scanning fields of view in space. These multiple sub-scanning fields of view are stitched together to form the total detection field of view of the lidar, completing one detection of the first detection range, and acquiring the first point cloud through the light receiving device 23. The light emitting device 22 emits a second set of detection beams L2, which are reflected by the second reflecting surface 212 of the scanning device 21 and then emitted to the outside of the lidar 20. As the scanning device 21 rotates, the second reflecting surface 212 stops at multiple angles, causing the second set of detection beams L2 to form multiple sub-scanning fields of view in space. These multiple sub-scanning fields of view are stitched together to form the total detection field of view of the lidar, completing one detection of the second detection range, and acquiring the second point cloud through the light receiving device 23. The first detection range and the second detection range correspond to different detection distances.

[0078] Figure 5AA schematic diagram of a detection method using a first reflective surface according to an embodiment of the present invention is shown. The scanning device 21 is a four-sided rotating mirror, including two first reflective surfaces 211 and two second reflective surfaces 212. The first reflective surfaces 211 reflect the first set of detection beams L1 to the outside of the lidar 20 and receive the first set of echoes L1' reflected from the first set of detection beams L1 on the obstacle. Specifically, the light emitting device 22 includes a laser array, which emits one or more probe beams according to a preset timing sequence. At this time, the first reflecting surface 211 is located at an angle θ1, and the first reflecting surface 211 reflects one or more probe beams emitted by the laser array to the outside of the lidar 20, forming a first sub-scanning field of view. At the next moment, the laser array continues to emit one or more probe beams according to the preset timing sequence, and the first reflecting surface 211 rotates to an angle θ2 accordingly, reflecting one or more probe beams emitted by the laser array to the outside of the lidar 20, forming a second sub-scanning field of view. This process is repeated until the first reflecting surface 211 stops reflecting the probe beams, forming a total of N sub-scanning fields of view, where N≥2. Throughout the process, one or more probe beams emitted by the laser array form the first set of probe beams L1. As the scanning device 21 rotates, the first reflective surface 211 rotates to different angles, reflecting the first set of probe beams L1 to different angles in space to form multiple sub-scanning fields of view. After the first set of probe beams L1 is reflected on the obstacle, it forms the first set of echoes L1'. Then, as the scanning device 21 rotates, the first reflective surface 211 rotates to different angles to receive the first set of echoes L1' corresponding to all the first set of probe beams L1. All the sub-scanning fields of view are stitched together to form the total detection field of view of the lidar, and the set of point data in it forms the first point cloud.

[0079] Figure 5B This diagram illustrates a detection method using a second reflective surface according to an embodiment of the present invention. The scanning device 21 is a four-sided rotating mirror. The second reflective surface 212 reflects the second set of detection beams L2 to the outside of the lidar 20 and receives the second set of echoes L2' reflected from the second set of detection beams L2 on obstacles. The process is as described above: one or more columns of detection beams emitted by the laser array form the second set of detection beams L2. By rotating the scanning device 21, the first reflective surface 211 rotates to different angles, reflecting the second set of detection beams L2 to different angles in space, forming multiple sub-scanning fields of view. After the second set of detection beams L2 are reflected on obstacles, they form the second set of echoes L2'. Again, by rotating the scanning device 21, the second reflective surface 212 rotates to different angles, receiving all the second set of echoes L2' corresponding to the second set of detection beams L2. All sub-scanning fields of view are stitched together to form the total detection field of view of the lidar, and the set of point data within it forms the second point cloud.

[0080] It can be seen that by using different reflective surfaces of the scanning device 21, long-range detection and short-range detection can be separated, and then the control parameters of the lidar (such as adjusting the light intensity of the laser and the bias voltage of the detector) can be adjusted to suppress stray light, thereby solving the problem of near-range blind zone.

[0081] According to a preferred embodiment of the present invention, the effective reflective area of ​​the first reflective surface 211 is greater than the effective reflective area of ​​the second reflective surface 212. Generally, the detection range is proportional to the effective reflective area of ​​the reflective surface. Figure 6 A schematic diagram of a reflecting surface and incident light according to an embodiment of the present invention is shown. Assuming the total area of ​​the reflecting surface is S, the effective reflecting area of ​​the reflecting surface is S*cosθ, where θ is the angle between the reflecting surface and the direction perpendicular to the optical axis of the incident light. For example, the total area of ​​the first reflecting surface 211 is S1, and the effective reflecting area is S1*cosθ1; the total area of ​​the second reflecting surface 212 is S2, and the effective reflecting area is S2*cosθ2. When S1*cosθ1 > S2*cosθ2, the first detection range is greater than the second detection range.

[0082] According to a preferred embodiment of the present invention, the ratio of the effective reflective areas of the first reflective surface 211 and the second reflective surface 212 is determined based on the ratio of the detection ranges corresponding to the first point cloud and the second point cloud.

[0083] Specifically, the total area of ​​the first reflecting surface 211 is S1, with an effective reflecting area of ​​S1*cosθ1; the total area of ​​the second reflecting surface 212 is S2, with an effective reflecting area of ​​S2*cosθ2. Therefore, the ratio of the effective reflecting areas of the first reflecting surface 211 and the second reflecting surface 212 is S1*cosθ1 / S2*cosθ2, and this ratio is related to the ratio of the first detection range to the second detection range. For example, if the first detection range is 200 meters and the second detection range is 50 meters, then the ratio of the effective reflecting areas of the first reflecting surface 211 and the second reflecting surface 212 is approximately 1 / 4 to 1 / 3. Therefore, by setting the ratio of the effective reflecting areas of the first reflecting surface 211 and the second reflecting surface 212, the detection ranges corresponding to the first and second point clouds can be adjusted, thereby achieving different ranging performances for different detection ranges, such as higher detection resolution within the detection range corresponding to the second point cloud.

[0084] The relationship between the effective reflective area and the detection range of the scanning device 21 has been explained in detail above through preferred embodiments. Using the design scheme of the present invention, the control parameters of the lidar can also be freely adjusted to solve the problem of near-range blind spots. The following describes the preferred embodiments in detail.

[0085] According to another preferred embodiment of the present invention, step S101 of the detection method 10 includes: controlling the light emitting device 22 to emit a first set of detection beams L1 at a first power; step S103 includes: controlling the light emitting device 22 to emit a second set of detection beams L2 at a second power, wherein the first power is greater than the second power. Figure 7 As shown, the scanning device 21 is, for example, a four-sided rotating mirror. Within one rotation cycle of 360 degrees, the two first reflecting surfaces 211 correspond to two detections within the first detection range, and the two second reflecting surfaces 212 correspond to two detections within the second detection range, obtaining a total of 4 frames of point cloud. During the detection time corresponding to the first detection range, the light emitting device 22 emits the first set of detection beams L1 at a first power to achieve a greater ranging capability. During the detection time corresponding to the second detection range, the light emitting device 22 emits the second set of detection beams L2 at a second power lower than the first power to reduce stray light intensity. This ensures that the stray light level is controlled to a level that will not cause saturation of the light receiving device 23 or prevent the target echo from being unidentifiable, thereby solving the problem of near-range blind spots.

[0086] According to a preferred embodiment of the present invention, the second power is 1%-10% of the first power. For example, during the detection time corresponding to the first detection range, the optical emitting device 22 emits the first set of detection beams L1 at 100% power to achieve maximum ranging capability; during the detection time corresponding to the second detection range, the optical emitting device 22 emits the second set of detection beams L2 at a relative power of 1%-10% of the first power to suppress stray light interference with the lidar.

[0087] According to another preferred embodiment of the present invention, step S102 of the detection method 10 includes: applying a first bias voltage to the light receiving device 23; step S104 includes: applying a second bias voltage to the light receiving device 23; wherein, the detection performance of the light receiving device 23 under the first bias voltage is higher than the detection performance under the second bias voltage. The light receiving device 23 of the lidar 20 typically operates under a certain bias voltage, and its detection performance is related to the bias voltage. Within a certain range, the higher the bias voltage, the higher the detection performance, or the higher the detection sensitivity.

[0088] Taking the light receiving device 23, which includes at least one photodetector 231, as an example, the photodetector 231 is, for example, a silicon photomultiplier tube (SiPM). Detection saturation is suppressed by adjusting the bias voltage of the SiPM. Specifically, within a first detection range, the first bias voltage applied to the SiPM is increased, thereby improving the SiPM's response capability; within a second detection range, the second bias voltage applied to the SiPM is decreased to reduce the single-photon detection efficiency (PDE), thus weakening the SiPM's response capability and making it less prone to saturation.

[0089] Furthermore, the bias voltage of the optical receiver 23 of the lidar 20 can be dynamically adjusted according to the emission time of the detection beam of the lidar 20. For example, before the emission time of the detection beam, the bias voltage of the optical receiver 23 can be adjusted to a lower value to reduce the response of the optical receiver 23 to stray light. After the emission time of the detection beam, the bias voltage of the optical receiver 23 is gradually restored to the normal operating voltage so that its response capability is restored to the normal level to receive the echo signal, thereby suppressing the interference of stray light on the optical receiver 23 and suppressing the crosstalk caused by the bias voltage switching.

[0090] According to a preferred embodiment of the present invention, the detection method 10 further includes adjusting a first bias voltage and / or a second bias voltage based on one or more of the intensity of a first set of detection beams L1, the intensity of a second set of detection beams L2, the obstacle distance, the obstacle reflectivity, and the maximum detection distance. Adjusting the bias voltage based on the intensity of the detection beams, the detection distance, the obstacle distance, and the reflectivity can prevent the light receiving device 23 from saturating and expand the dynamic range of the light receiving device 23.

[0091] According to a preferred embodiment of the present invention, the detection method 10 further includes: adjusting a first bias voltage and / or a second bias voltage based on the intensity of the previous echo. As the intensity of the previous echo increases, the second bias voltage is decreased. In this embodiment, the bias voltage for the next detection is adjusted based on the strength of the previous echo signal to make a prediction. If the intensity of the previous echo is high, the second bias voltage for the next detection can be appropriately lower. For example, when the transmit power decreases, the first bias voltage can be increased so that the SiPM is not completely turned off. While controlling the amplitude of spurious signals, the voltage jump amplitude is reduced, preserving a certain amount of subsequent SiPM receiving capability. In this embodiment, adjusting the first bias voltage based on the intensity of the probe beam can suppress crosstalk caused by bias voltage switching, and at the same time, can quickly restore the receiving capability of the optical receiving device 23, allowing the SiPM to retain more receiving capability in the off state (because the crosstalk to the baseline is small, the waiting time for responding to and recognizing signals is reduced).

[0092] According to a preferred embodiment of the present invention, the detection method 10 further includes: slowly switching a first bias voltage or a second bias voltage based on the emission time of the detection laser beam. Through the embodiments of the present invention, the effect of suppressing stray light can be improved by gradually increasing the voltage, i.e., slowly switching the first bias voltage to the second bias voltage; adjusting the bias voltage based on the intensity of the detection beam reduces crosstalk to the baseline of the electrical signal, shortens the waiting time for responding to and recognizing the signal, and thus suppresses crosstalk caused by bias voltage switching while quickly restoring the receiving capability of the optical receiving device 23.

[0093] In summary, by controlling the transmission power of the optical transmitter 22 and the bias voltage of the optical receiver 23, stray light can be suppressed, thereby improving the ranging capability.

[0094] The design scheme of this invention also allows for free adjustment of the resolution of different detection ranges. The following describes the preferred embodiments in detail.

[0095] According to a preferred embodiment of the present invention, step S102 in the detection method 10 includes: controlling the scanning device 21 to rotate at a first rotational speed; step S104 includes: controlling the scanning device 21 to rotate at a second rotational speed.

[0096] refer to Figure 4 The lidar 20 also includes a motor 25 and an encoder disk (not shown). The motor 25 is configured to drive the scanning device 21 to rotate. When the motor 25 rotates at a constant speed, the horizontal resolution of the first detection range and the second detection range is exactly the same. This is because the field of view of the first detection range and the second detection range is the same, for example, both are 120°, and the corresponding encoder disk rotation angle is 60°. Furthermore, the encoding time interval for the same system is the same (i.e., the encoder disk scales are equally spaced, and the lidar performs emission detection based on the encoder disk scale). When the scanning device 21 rotates at a constant speed, the duration and horizontal resolution for measuring the first detection range and the second detection range are the same.

[0097] According to a preferred embodiment of the present invention, the output of the motor 25 can be controlled to change the rotation speed of the scanning device 21. For example, within a first detection range, the motor 25 can be controlled to make the rotation speed of the scanning device 21 faster, while within a second detection range, the motor 25 can be controlled to make the rotation speed of the scanning device 21 slower, thereby emitting more detection beams and obtaining more echoes, thus achieving higher horizontal resolution at close range. Alternatively, when a high resolution is not desired within the second detection range (e.g., the close-range detection range) and obstacle avoidance is the only objective, the motor 25 can be controlled to appropriately increase the rotation speed of the scanning device 21 corresponding to the second detection range, resulting in a lower resolution. However, this allows more flight time for the first set of detection beams L1 corresponding to the first detection range, enabling the lidar to detect obstacles at a greater distance more accurately.

[0098] The advantage of giving the first set of detection beams L1 more flight time is the improved range measurement performance of the lidar. The different lasers of the optical emitting device 22 are serial. If the flight time window of each channel requires the lidar to extend the detection distance from 200m to 300m, then the time corresponding to one reflector is not enough. It is necessary to reduce the rotation speed of the first reflector 211 corresponding to the first detection range, which will reduce the resolution of the first detection range. Therefore, by increasing the rotation speed of the second reflector 212 corresponding to the second detection range, more flight time will be left for the first set of detection beams L1.

[0099] Therefore, by adjusting the rotation speed of the motor 25, and thus controlling the rotation speed of the scanning device 21, the ratio of measurement time for the first and second detection ranges can be freely adjusted, thereby allowing for customization of the horizontal resolution of the lidar 20 and improvement of its range measurement performance according to system requirements.

[0100] According to another preferred embodiment of the present invention, the detection method 10 further includes adjusting the first rotation speed and / or the second rotation speed according to the detection scenario or resolution of the lidar 20. For example, in a highway or search and rescue scenario, where improved range performance is required, the second rotation speed can be increased to allow for more flight time within the first detection range. Alternatively, in a non-standard urban road or congested traffic area, where improved short-range horizontal resolution is required, the second rotation speed can be decreased to achieve higher horizontal resolution within the second detection range.

[0101] According to another preferred embodiment of the present invention, the detection method 10 further includes: dynamically adjusting the emission repetition rate of the first set of detection beams L1 and / or the emission repetition rate of the second set of detection beams L2 based on the detection results. The emission repetition rate refers to the repetition frequency of the laser pulses emitted by the laser. For example, if the rotation speed of the scanning device 21 remains constant, for the first detection range, the time interval between the rotation of the first set of detection beams L1 is shortened, and the extra idle time is used for repeated scanning of key areas.

[0102] According to a preferred embodiment of the present invention, the detection result includes: the area where the obstacle is located and / or the region of interest. For example, if an obstacle is detected in the first detection range, the repetition rate of the first set of detection beams L1 is increased, that is, the first set of detection beams L1 is emitted in a shorter time, and the extra idle time is used to repeatedly scan the area where the obstacle is located, thereby improving the spatial resolution of that area. Or, for example, if it is necessary to improve the detection resolution of a certain region of interest in the second detection range, the emission interval of the second set of detection beams L2 is shortened, that is, the second set of detection beams L2 is emitted in a shorter time, and the extra idle time is used to repeatedly scan the region of interest. By repeatedly scanning local areas, the local resolution is improved, thereby allowing for customized resolution. For example, in traffic congestion scenarios or when vehicles are turning, more attention is paid to obstacles at close range; increasing the repetition rate of the second set of detection beams L2 and repeatedly scanning the area where the close-range obstacle is located helps to cope with complex scenarios.

[0103] In summary, by controlling the rotation speed of the scanning device 21 and the repetition rate of the light emitting device 22, the time ratio of different detection ranges can be freely adjusted, thereby allowing for custom detection resolution.

[0104] Figure 8 A schematic diagram of stray light and target echoes (i.e., the first set of echoes and the second set of echoes) according to an embodiment of the present invention is shown. By controlling the emission power of the laser and the bias voltage of the detector, it can be seen that when the target is far away, the first set of echoes and the stray light echoes are far apart in time, so even if the stray light intensity is relatively high, the first set of echoes will not be affected. When the target is close, the stray light echoes are reduced to a very low level, and the second set of echoes can also be identified relatively well. It can be seen that the present invention separates long-range detection (corresponding to the first detection range) and short-range detection (corresponding to the second detection range), and adjusts the control parameters of the lidar (e.g., adjusting the light intensity of the laser and the bias voltage of the detector) for short-range detection, effectively suppressing stray light and thus solving the problem of near-range blind zone.

[0105] According to a preferred embodiment of the present invention, the scanning device 21 includes a plurality of first reflective surfaces 211 and a plurality of second reflective surfaces 212. The detection method 10 further includes: fusing at least two of the multiple point clouds acquired by the plurality of first reflective surfaces 211 respectively into a first point cloud, and fusing at least two of the multiple point clouds acquired by the plurality of second reflective surfaces 212 respectively into a second point cloud. For example, the scanning device 21 is a 6-face rotating mirror, including three first reflective surfaces 211 and three second reflective surfaces 212. Within one rotation cycle, the three first reflective surfaces 211 correspond to three detections within a first detection range, and the three second reflective surfaces 212 correspond to three detections within a second detection range, obtaining a total of 6 frames of point clouds. At least two of the points acquired by the three first reflective surfaces 211 are fused into a first point cloud; at least two of the points acquired by the three second reflective surfaces 212 are fused into a second point cloud. In this embodiment, multiple point clouds with the same detection range are fused.

[0106] According to a preferred embodiment of the present invention, the detection method 10 further includes: fusing the first point cloud and the second point cloud to obtain a frame of point cloud within the detection range of the lidar. In this embodiment, point clouds from different detection ranges are fused and stitched together. For example, the first point cloud corresponds to a detection range of 0-200 meters, and the second point cloud corresponds to a detection range of 0-20 meters; the first point cloud and the second point cloud are fused into a single frame of point cloud.

[0107] According to a preferred embodiment of the present invention, the detection method 10 further includes: synchronizing the first point cloud and the second point cloud in time based on the motion information of the lidar 20, and then fusing them. Because there is a time difference between the first and second point clouds measured in a time-division manner, the stitching effect can be optimized by increasing the rotation speed of the rotating mirror; alternatively, at a specific rotation speed, such as 10Hz, the two point clouds can be fused into a single point cloud using a post-processing algorithm. Commonly used post-processing algorithms include registration based on feature matching, Normal Distribution Transform (NDT), and Iterative Closest Point (ICP). The time synchronization processing of the first and second point clouds is based on the motion information of the lidar 20, where the motion information includes the velocity and pose of the lidar 20.

[0108] According to a preferred embodiment of the present invention, the detection method 10 further includes: selecting points from the first point cloud that correspond to points outside the detection range of the second point cloud and fusing them with the second point cloud. (See reference) Figure 4 For example, the first detection range is 0-200 meters, and the second detection range is 0-50 meters. Points within 50-200 meters are selected from the first point cloud and fused with the second point cloud.

[0109] According to a preferred embodiment of the present invention, the detection method 10 further includes: fusing points in the first point cloud that correspond to the detection range of the second point cloud with the second point cloud. (See reference) Figure 4 For example, the first detection range is 0-200 meters, and the second detection range is 0-50 meters. The points in the first point cloud within the 0-50 meter range are then fused with the points in the second point cloud.

[0110] In summary, by using time-division detection, controlling the laser intensity and detector bias, and point cloud fusion, the problem of near-range blind zone in the lidar solution of the coaxial transceiver system is effectively solved, and the resolution of different detection ranges can be customized.

[0111] The present invention also relates to a computer storage medium including computer executable instructions stored thereon, wherein the executable instructions, when executed by a processor, implement the detection method 10 as described above.

[0112] The present invention also relates to a lidar 30, see reference Figure 9 The lidar 30 includes:

[0113] The light emitting device 32 includes at least one laser 321, such as laser 321-1, ..., laser 321-n, configured to emit detection beams respectively;

[0114] The light receiving device 33 includes at least one detector 331, such as detector 331-1, ..., detector 331-n, configured to receive the echo of the detection beam on the obstacle respectively;

[0115] The scanning device 31 is configured to reflect a first set of detection beams L1 emitted by the light emitting device 32 to the outside of the lidar 30, and to receive a first set of echoes L1' of the first set of detection beams L1 on an obstacle; it is also configured to reflect a second set of detection beams L2 emitted by the light emitting device 32 to the outside of the lidar 30, and to receive a second set of echoes L2' of the second set of detection beams L2 on an obstacle;

[0116] Processing unit 34, coupled to the optical emitting device 32 and the optical receiving device 33, is configured to acquire a first point cloud based on the first set of echoes L1' and acquire a second point cloud based on the second set of echoes L2';

[0117] The first point cloud and the second point cloud correspond to different detection ranges.

[0118] According to a preferred embodiment of the present invention, the scanning device 31 includes at least one first reflective surface and at least one second reflective surface, wherein the first reflective surface reflects the first set of detection beams L1 to the outside of the lidar 30 and receives the first set of echoes L1', and the second reflective surface reflects the second set of detection beams L2 to the outside of the lidar 30 and receives the second set of echoes L2'.

[0119] According to a preferred embodiment of the present invention, the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface.

[0120] According to a preferred embodiment of the present invention, the processing unit 34 is configured to perform the detection method 10 as described above to obtain a first point cloud and a second point cloud and fuse them into a single frame of point cloud.

[0121] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A detection method for a lidar, the lidar comprising a scanning device, the detection method comprising: S101: Firing the first set of probe beams; S102: The scanning device reflects the first set of detection beams to the outside of the lidar and receives the first set of echoes of the first set of detection beams on the obstacle to obtain the first point cloud; S103: Firing the second set of probe beams; and S104: The scanning device reflects the second set of detection beams to the outside of the lidar and receives the second set of echoes of the second set of detection beams on the obstacle to obtain the second point cloud; The scanning device includes at least one first reflective surface and at least one second reflective surface; Step S102 includes: reflecting the first set of detection beams to the outside of the lidar through the first reflective surface and receiving the first set of echoes, and acquiring the first point cloud through the light receiving device; Step S104 includes reflecting the second set of detection beams to the outside of the lidar through the second reflective surface and receiving the second set of echoes, and acquiring the second point cloud through the light receiving device. The first point cloud and the second point cloud correspond to different detection ranges.

2. The detection method according to claim 1, wherein the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface; wherein the ratio of the effective reflective areas of the first reflective surface and the second reflective surface is determined according to the ratio of the detection distances corresponding to the first point cloud and the second point cloud.

3. The detection method according to claim 1, wherein step S102 includes: The scanning device is controlled to rotate at a first speed; Step S104 includes: controlling the scanning device to rotate at a second rotation speed; wherein the first rotation speed is different from the second rotation speed; The detection method further includes adjusting the first rotation speed and / or the second rotation speed according to the detection scene or resolution of the lidar.

4. The detection method according to claim 1, wherein the lidar further includes a light emitting device, wherein step S101 includes: The optical emitting device is controlled to emit a first set of detection beams at a first power; Step S103 includes: controlling the light emitting device to emit a second set of detection beams at a second power, wherein the first power is greater than the second power.

5. The detection method according to claim 1 further includes: The emission repetition rate of the first group of detection beams and / or the emission repetition rate of the second group of detection beams are dynamically adjusted based on the detection results. The detection results include: the area where the obstacle is located and / or the region of interest.

6. The detection method according to claim 1, wherein the lidar further includes a light receiving device, wherein step S102 includes: The optical receiving device is subjected to a first bias voltage; Step S104 includes: applying a second bias voltage to the optical receiving device; wherein the detection performance of the optical receiving device under the first bias voltage is higher than the detection performance under the second bias voltage; The detection method further includes adjusting the first bias voltage and / or the second bias voltage based on one or more of the intensity of the first set of detection beams, the intensity of the second set of detection beams, the obstacle distance, the obstacle reflectivity, and the maximum detection distance.

7. The detection method according to claim 2, wherein the scanning device comprises a plurality of first reflecting surfaces and a plurality of second reflecting surfaces, and the detection method further comprises: At least two of the multiple point clouds obtained corresponding to the multiple first reflective surfaces are fused into the first point cloud, and at least two of the multiple point clouds obtained corresponding to the multiple second reflective surfaces are fused into the second point cloud.

8. The detection method according to any one of claims 1-7, further comprising: The first point cloud and the second point cloud are fused to obtain a frame of point cloud within the detection range of the lidar.

9. The detection method according to claim 8 further includes: Based on the motion information from the lidar, the first point cloud and the second point cloud are synchronized in time and then fused. Alternatively, select points from the first point cloud that are outside the detection range of the second point cloud and fuse them with the second point cloud; or, fuse points from the first point cloud that are within the detection range of the second point cloud with the second point cloud.

10. A lidar, comprising: An optical emitting device includes at least one laser configured to emit probe beams separately; A light receiving device includes at least one detector configured to receive the echoes of the detection beam on an obstacle, respectively. A scanning device is configured to reflect a first set of detection beams emitted by the light emitting device to the outside of the lidar, and to receive a first set of echoes of the first set of detection beams on an obstacle; it is also configured to reflect a second set of detection beams emitted by the light emitting device to the outside of the lidar, and to receive a second set of echoes of the second set of detection beams on an obstacle; the scanning device includes at least one first reflecting surface and at least one second reflecting surface; the first set of detection beams is reflected to the outside of the lidar through the first reflecting surface and the first set of echoes are received; The second set of detection beams is reflected to the outside of the lidar by the second reflective surface, and the second set of echoes is received. The processing unit, coupled to the optical emitting device and the optical receiving device, is configured to acquire a first point cloud based on the first set of echoes and acquire a second point cloud based on the second set of echoes. The first point cloud and the second point cloud correspond to different detection ranges.

11. The lidar according to claim 10, wherein the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface.

12. The lidar according to claim 10 or 11, wherein the processing unit is configured to perform the detection method according to any one of claims 1-9 to acquire the first point cloud and the second point cloud and fuse them into a single frame point cloud.

13. A detection method for a lidar, the lidar comprising a scanning device, the detection method comprising: S101: Firing the first set of probe beams at the first power; S102: The scanning device reflects the first set of detection beams to the outside of the lidar and receives the first set of echoes of the first set of detection beams on the obstacle to obtain the first point cloud; S103: Firing the second set of probe beams at the second power; and S104: The scanning device reflects the second set of detection beams to the outside of the lidar and receives the second set of echoes of the second set of detection beams on the obstacle to obtain the second point cloud; The scanning device includes at least one first reflective surface and at least one second reflective surface; Step S102 includes: reflecting the first set of detection beams to the outside of the lidar through the first reflective surface and receiving the first set of echoes, and acquiring the first point cloud through the light receiving device; Step S104 includes reflecting the second set of detection beams to the outside of the lidar through the second reflective surface and receiving the second set of echoes, and acquiring the second point cloud through the light receiving device. The first power is greater than the second power.

14. The detection method according to claim 13, wherein the first point cloud and the second point cloud correspond to different detection distances.

15. The detection method according to claim 13, wherein the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface; wherein the ratio of the effective reflective areas of the first reflective surface and the second reflective surface is determined according to the ratio of the detection distances corresponding to the first point cloud and the second point cloud.

16. The detection method according to claim 13, wherein the second power is 1%-10% of the first power; Step S102 includes: controlling the scanning device to rotate at a first rotational speed; step S104 includes: controlling the scanning device to rotate at a second rotational speed; wherein the first rotational speed is different from the second rotational speed; The detection method further includes adjusting the first rotation speed and / or the second rotation speed according to the detection scene or resolution of the lidar.

17. The detection method according to claim 13, further comprising: The emission repetition rate of the first group of detection beams and / or the emission repetition rate of the second group of detection beams are dynamically adjusted based on the detection results. The detection results include: the area where the obstacle is located and / or the region of interest.

18. The detection method according to claim 13, wherein the lidar further includes a light receiving device, wherein step S102 includes: The optical receiving device is subjected to a first bias voltage; Step S104 includes: applying a second bias voltage to the optical receiving device; wherein the detection performance of the optical receiving device under the first bias voltage is higher than the detection performance under the second bias voltage; The detection method further includes adjusting the first bias voltage and / or the second bias voltage based on one or more of the intensity of the first set of detection beams, the intensity of the second set of detection beams, the obstacle distance, the obstacle reflectivity, and the maximum detection distance.

19. The detection method according to any one of claims 13-18, further comprising: The first point cloud and the second point cloud are fused to obtain a frame of point cloud within the detection range of the lidar.

20. The detection method according to claim 19, further comprising: Based on the motion information from the lidar, the first point cloud and the second point cloud are synchronized in time and then fused. Alternatively, select points from the first point cloud that are outside the detection range of the second point cloud and fuse them with the second point cloud; or, fuse points from the first point cloud that are within the detection range of the second point cloud with the second point cloud.

21. A lidar, comprising: An optical emitting device includes at least one laser configured to emit a first set of probe beams at a first power or a second set of probe beams at a second power; A light receiving device includes at least one detector configured to receive the echoes of the detection beam on an obstacle, respectively. A scanning device is configured to reflect a first set of detection beams emitted by the light emitting device to the outside of the lidar, and receive a first set of echoes of the first set of detection beams on an obstacle; reflect a second set of detection beams emitted by the light emitting device to the outside of the lidar, and receive a second set of echoes of the second set of detection beams on an obstacle; the scanning device includes at least one first reflecting surface and at least one second reflecting surface; the first set of detection beams is reflected to the outside of the lidar through the first reflecting surface and the first set of echoes are received; The second set of detection beams is reflected to the outside of the lidar by the second reflective surface, and the second set of echoes is received. The processing unit, coupled to the optical emitting device and the optical receiving device, is configured to acquire a first point cloud based on the first set of echoes and acquire a second point cloud based on the second set of echoes. The first power is greater than the second power.

22. The lidar according to claim 21, wherein the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface.

23. The lidar according to claim 21 or 22, wherein the processing unit is configured to perform the detection method according to any one of claims 13-20 to acquire the first point cloud and the second point cloud and fuse them into a single frame of point cloud.

24. A detection method for a lidar, the lidar including a scanning device, the detection method comprising: S101: Firing the first set of probe beams; S102: Control the scanning device to rotate at a first rotation speed to reflect the first set of detection beams to the outside of the lidar, and receive the first set of echoes of the first set of detection beams on the obstacle to obtain the first point cloud; S103: Firing the second set of probe beams; and S104: Control the scanning device to rotate at a second rotation speed to reflect the second set of detection beams to the outside of the lidar, and receive the second set of echoes of the second set of detection beams on the obstacle to obtain the second point cloud; The scanning device includes at least one first reflective surface and at least one second reflective surface; Step S102 includes: reflecting the first set of detection beams to the outside of the lidar through the first reflective surface and receiving the first set of echoes, and acquiring the first point cloud through the light receiving device; Step S104 includes reflecting the second set of detection beams to the outside of the lidar through the second reflective surface and receiving the second set of echoes, and acquiring the second point cloud through the light receiving device. The first rotational speed is different from the second rotational speed.

25. The detection method according to claim 24, wherein the first point cloud and the second point cloud correspond to different detection distances; The step S101 includes: emitting the first set of detection beams at a first power; the step S103 includes: emitting the second set of detection beams at a second power.

26. The detection method according to claim 24, wherein the effective reflective area of ​​the first reflective surface is greater than the effective reflective area of ​​the second reflective surface; wherein the ratio of the effective reflective areas of the first reflective surface and the second reflective surface is determined according to the ratio of the detection distances corresponding to the first point cloud and the second point cloud.

27. The detection method according to claim 25, wherein the first power is greater than the second power; and the first rotational speed is lower than the second rotational speed; The detection method further includes: Adjust the first rotation speed and / or the second rotation speed according to the detection scene or resolution of the lidar.

28. The detection method according to claim 24, further comprising: The emission repetition rate of the first group of detection beams and / or the emission repetition rate of the second group of detection beams are dynamically adjusted based on the detection results. The detection results include: the area where the obstacle is located and / or the region of interest.

29. The detection method according to claim 24, wherein the lidar further includes a light receiving device, wherein step S102 includes: The optical receiving device is subjected to a first bias voltage; Step S104 includes: applying a second bias voltage to the optical receiving device; wherein the detection performance of the optical receiving device under the first bias voltage is higher than the detection performance under the second bias voltage; The detection method further includes adjusting the first bias voltage and / or the second bias voltage based on one or more of the intensity of the first set of detection beams, the intensity of the second set of detection beams, the obstacle distance, the obstacle reflectivity, and the maximum detection distance.

30. The detection method according to any one of claims 24-29, further comprising: The first point cloud and the second point cloud are fused to obtain a frame of point cloud within the detection range of the lidar.

31. The detection method according to claim 30, further comprising: Based on the motion information from the lidar, the first point cloud and the second point cloud are synchronized in time and then fused. Alternatively, select points from the first point cloud that are outside the detection range of the second point cloud and fuse them with the second point cloud; or, fuse points from the first point cloud that are within the detection range of the second point cloud with the second point cloud.

32. A lidar, comprising: An optical emitting device, comprising at least one laser configured to emit a probe beam; A light receiving device includes at least one detector configured to receive the echoes of the detection beam on an obstacle, respectively. A scanning device is configured to rotate at a first rotational speed to reflect a first set of detection beams emitted by the light emitting device to the outside of the lidar and to receive a first set of echoes of the first set of detection beams on an obstacle; and to rotate at a second rotational speed to reflect a second set of detection beams emitted by the light emitting device to the outside of the lidar and to receive a second set of echoes of the second set of detection beams on an obstacle; the scanning device includes at least one first reflecting surface and at least one second reflecting surface; the first reflecting surface reflects the first set of detection beams to the outside of the lidar and receives the first set of echoes; The second set of detection beams is reflected to the outside of the lidar by the second reflective surface, and the second set of echoes is received. The processing unit, coupled to the optical emitting device and the optical receiving device, is configured to acquire a first point cloud based on the first set of echoes and acquire a second point cloud based on the second set of echoes. The first rotational speed is different from the second rotational speed.

33. The lidar according to claim 32, wherein the first point cloud and the second point cloud correspond to different detection distances; the light emitting device is configured to: emit the first set of detection beams at a first power and emit the second set of detection beams at a second power, wherein the first power is greater than the second power; The effective reflective area of ​​the first reflective surface is greater than that of the second reflective surface.

34. The lidar according to claim 32 or 33, wherein the processing unit is configured to perform the detection method according to any one of claims 24-31 to acquire the first point cloud and the second point cloud and fuse them into a single frame point cloud.

35. A computer storage medium comprising computer-executable instructions stored thereon, the executable instructions, when executed by a processor, implementing the detection method as described in any one of claims 1-9, 13-20, and 24-31.

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