A laser radar detection method, laser radar and computer-readable storage medium

Abstract

The present application belongs to the field of laser radar, and specifically relates to a detection method of laser radar, including: emitting a main laser beam multiple times, and there is at least partial overlap between the receiving and analyzing areas of at least two emitted main laser beams; receiving a first echo; when the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam, determining each candidate flight time of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the receiving time of the first echo, respectively; obtaining the similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo, and determining the true flight time of the first echo from the candidate flight times of the first echo according to the similarity.

Description

Technical Field

[0001] The present application relates to the field of laser radar, and in particular to a laser radar detection method, a laser radar and a computer-readable storage medium. Background Art

[0002] LiDAR consists of a transmitting system, a receiving system, a scanning control system, and a data processing system. It measures distance by measuring the time difference between the emitted detection laser and the received echo laser. It has the advantages of high resolution, high sensitivity, strong anti-interference ability, and is not affected by lighting conditions. It has been widely used in autonomous driving, logistics vehicles, robots, vehicle-road collaboration, and public smart transportation.

[0003] The point frequency and ranging range of the laser radar are both very important indicators. For one of the transceiver modules of the laser radar, its point frequency refers to the frequency at which the transceiver module measures per unit time. The ranging range refers to the minimum distance to the maximum distance that the transceiver module can measure. Generally, during design, in order to prevent the echoes of two adjacent laser emissions from interfering with each other, the time interval between two adjacent emissions must be greater than the duration corresponding to the maximum ranging distance of one emission. However, such limitations lead to certain contradictions between the ranging range and the point frequency. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present application aims to provide a laser radar detection method, comprising:

[0005] Fire the main laser beam multiple times,

[0006] The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially, and the receiving and analyzing areas of the main laser beams take the emission time of the main laser beams as a starting point and the flight time corresponding to the maximum detection distance of the main laser beams as a duration;

[0007] Wherein, the time intervals between any two adjacent emissions of the multiple main laser beams are different;

[0008] Wherein, the main laser beams emitted at least twice include adjacent first laser beams and second laser beams;

[0009] Receive the first echo;

[0010] When the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam, determining candidate flight times of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo, respectively;

[0011] obtaining similarities between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo,

[0012] The actual flight time of the first echo is determined from the candidate flight times of the first echo according to the similarity.

[0013] Optionally, the at least one adjacent echo of the first echo includes at least one adjacent echo received before the first echo, or includes at least one adjacent echo received before and at least one adjacent echo received after the first echo.

[0014] Optionally, determining the true flight time of the first echo from the candidate flight times of the first echo according to the similarity includes: when there is a similarity less than a preset threshold, determining the candidate flight time of the first echo corresponding to the similarity less than the preset threshold as the true flight time of the first echo.

[0015] Optionally, when there is no similarity less than the preset threshold, the first echo is determined to be noise.

[0016] Optionally, the method further includes: adjusting the preset threshold according to the ambient light noise of the laser radar and / or the movement speed of the laser radar.

[0017] Optionally, the multiple main laser beams are emitted in sequence at intervals of an emission period T plus or minus a randomly generated offset duration, and the offset durations corresponding to any two adjacent main laser beams are different.

[0018] Optionally, the flight time of at least one adjacent echo of the first echo includes two candidate flight times of at least one adjacent echo;

[0019] The method of obtaining the similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo includes: obtaining the similarity between a larger candidate flight time of the first echo and a larger candidate flight time of at least one adjacent echo, and obtaining the similarity between a smaller candidate flight time of the first echo and a smaller candidate flight time of at least one adjacent echo.

[0020] Optionally, the method further comprises:

[0021] A secondary laser beam is emitted between two adjacent emissions of the multiple emitted main laser beams, and a receiving and analyzing area of ​​the secondary laser beam is located within a receiving and analyzing area of ​​the last emitted main laser beam;

[0022] receiving a second echo;

[0023] When the second echo is located within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the sub-laser beam, determining the candidate flight times of the second echo according to the emission time of the first laser beam, the emission time of the sub-laser beam and the receiving time of the second echo;

[0024] Acquire the similarity between the second echo and at least one adjacent echo of the second echo, including the similarity between each candidate flight time of the second echo and the flight time of at least one adjacent echo of the second echo, and / or the similarity between the waveform of the second echo and the waveform of at least one adjacent echo of the second echo;

[0025] The actual flight time of the second echo is determined from the candidate flight times of the second echo according to the similarity.

[0026] Optionally, the receiving and analyzing area of ​​the secondary laser beam is staggered from the receiving and analyzing areas of other laser beams except the adjacent main laser beam emitted last.

[0027] Optionally, acquiring the similarity between the second echo and at least one adjacent echo of the second echo includes:

[0028] The similarity between the second echo and at least one echo of the second echo located in a receiving and analyzing area of ​​an adjacent main laser beam is acquired.

[0029] Optionally, for any two adjacent emitted sub-laser beams, the emission time interval between one of the sub-laser beams and the last emitted main laser beam is different from the emission time interval between another sub-laser beam and the last emitted main laser beam;

[0030] The obtaining of the similarity between the second echo and at least one adjacent echo of the second echo comprises:

[0031] The similarity between each candidate flight time of the second echo and the flight time of at least one echo of the second echo located in the receiving and analyzing area of ​​the adjacent sub-laser beam is obtained.

[0032] The present application also provides a laser radar, comprising:

[0033] The transceiver module is used to transmit the main laser beam multiple times.

[0034] The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially, and the receiving and analyzing areas of the main laser beams take the emission time of the main laser beams as a starting point and the flight time corresponding to the maximum detection distance of the main laser beams as a duration;

[0035] Wherein, the time intervals between any two adjacent emissions of the multiple main laser beams are different;

[0036] Wherein, the at least twice emitted laser beams include a first laser beam and a second laser beam emitted adjacent to and after the first laser beam;

[0037] The transceiver module is also used to receive the first echo;

[0038] A processing module is used to determine each candidate flight time of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo, respectively, when the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam; obtain the similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo, and determine the real flight time of the first echo from the candidate flight times of the first echo according to the similarity.

[0039] The present application also provides a laser radar, characterized in that it includes:

[0040] Processor; and

[0041] A memory having executable codes stored thereon, which, when executed by the processor, causes the processor to execute any one of the methods described above.

[0042] The present application also provides a computer-readable storage medium having executable codes stored thereon. When the executable codes are executed by a processor of an electronic device, the processor is enabled to execute any one of the methods described above.

[0043] In the embodiment of the present application, by setting the receiving and analysis areas of the main laser light beams of at least two emissions to at least partially overlap, it is possible to achieve a high range while taking into account a high point frequency. However, it will result in the echo received in the overlapping area of ​​the receiving and analysis area being unable to determine which emission it corresponds to. According to the time difference between the emission time and the reception time, at least two flight times will be calculated, including a real flight time and a false flight time. Based on the assumption that adjacent received echoes are most likely reflected by the same object, the real flight times corresponding to adjacent echoes remain unchanged or approximate, and at the same time, by changing the duration of the interval between two adjacent emissions, the false flight times corresponding to adjacent echoes have a certain gap. Therefore, the real flight time can be identified from the similarity between each flight time calculated by the echo and the flight time of at least one adjacent echo. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a schematic diagram of the principle of the receiving and analyzing area of ​​the laser beam emitted by the lidar.

[0045] Figure 2 It is a schematic diagram of an embodiment of the laser radar detection method of the present application.

[0046] Figure 3 It is a schematic diagram of the receiving and analyzing area of ​​the first laser beam and the second laser beam emitted by the laser radar.

[0047] Figure 4 It is a schematic diagram of an embodiment of a receiving and analyzing area of ​​a main laser beam emitted by a laser radar.

[0048] Figure 5 It is a schematic diagram of an embodiment of a receiving and analyzing area of ​​a main laser beam and a secondary laser beam emitted by a laser radar.

[0049] Figure 6 It is a schematic diagram of an embodiment of a laser radar in an embodiment of the present application.

[0050] Figure 7 It is a schematic diagram of an embodiment of a laser radar in an embodiment of the present application. DETAILED DESCRIPTION

[0051] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings. Although the embodiments of the present application are shown in the accompanying drawings, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to make the present application more thorough and complete, and to fully convey the scope of the present application to those skilled in the art.

[0052] The terms used in this application are for the purpose of describing specific embodiments only and are not intended to limit this application. The singular forms of "a", "said" and "the" used in this application and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0053] It should be understood that although the terms "first", "second", "third", etc. may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of this application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0054] Laser radar is a radar system that uses a laser beam to detect the position, speed and other characteristic quantities of a target. Its working principle is to emit a laser beam to the target, and then calculate the time difference between the received reflected echo and the emitted laser beam, which is the flight time of the laser beam. The laser radar calculates the distance, direction and other parameters of the object that reflects the echo based on the flight time, thereby detecting the external environment. Laser radar generally includes a transceiver module and a processing module. The transceiver module converts electrical pulses into light pulses and transmits them, and then restores the light pulses reflected from the target into electrical pulses. The processing module calculates relevant information based on the electrical pulses. Optionally, the laser radar may also include a scanning module (such as a MEMS galvanometer) to change the emission direction of the emitted laser beam to achieve scanning of the laser beam within a certain field of view. The optical paths of the reflected laser and the emitted laser are coaxial, and the reflected laser returns through the scanning module-transceiver module path and is received by the receiver in the transceiver module. Laser radar can be single-channel scanning or multi-channel simultaneous or interleaved scanning. In the case of multi-channel scanning, it can be achieved through multiple sets of transceiver modules, and the light between each channel (outgoing laser and reflected laser) is isolated from each other.

[0055] The point frequency and ranging range of LiDAR are both very important indicators. Figure 1 This is a schematic diagram of the principle of the receiving and analyzing area of ​​the laser beam emitted by the laser radar. Figure 1 As shown, the times when the laser radar emits two adjacent laser beams are T0 and T1. For a laser beam emitted by a transceiver module of the laser radar at time T0, theoretically, the maximum flight time t_dis of the laser beam is equal to the flight time t1 from the laser emission to the farthest detectable target, plus the flight time t2 required to return from the target to the laser radar, where t1=t2. Then the maximum distance of the ranging range dis_max=c*t_dis / 2, where c represents the speed of light. The larger the maximum distance of the ranging range, the longer the maximum flight time, corresponding to the longer the analysis area time required to wait for reception processing after a single laser emission. The time interval between two adjacent emissions affects the point frequency. The higher the point frequency, the shorter the interval t_freq between two adjacent emissions. For the convenience of description, the receiving and analysis area of ​​the emitted laser beam is referred to as the emission time of the laser beam as the starting point, and the flight time corresponding to the maximum detection distance of the laser beam as the duration.

[0056] Generally, in design, in order to ensure that the laser echo of this emission can be received and to avoid the echo signal of emission n interfering with the echo signal of emission n+1, the receiving analysis area of ​​emission n needs to be smaller than t_freq to ensure that the echo signal of emission n does not fall after emission n+1. Such a limitation makes the ranging range and point frequency have certain contradictions: when the ranging range increases to a certain extent, that is, t_dis increases, t_freq also needs to increase, so that the point frequency decreases; or, when the point frequency increases to a certain extent, t_dis decreases, so that the ranging range decreases.

[0057] In the embodiment of the present application, the contradiction between the point frequency and the ranging range is eliminated by overlapping the receiving analysis areas of two adjacent transmissions, that is, the receiving analysis area of ​​transmission n is greater than the time interval between transmission n and transmission n+1. At the same time, when the received echo falls into the overlapping area of ​​two adjacent receiving analysis areas, the similarity between the receiving time of the echo and the adjacent echo is used to determine which receiving analysis area the echo belongs to, so as to solve the interference problem caused by the overlapping of the receiving analysis areas. The embodiment of the present application is described by example in conjunction with the accompanying drawings.

[0058] like Figure 2 As shown, Figure 2 : is a schematic diagram of an embodiment of a laser radar detection method of the present application. The detection method includes:

[0059] S201, emitting a main laser beam multiple times and receiving a first echo.

[0060] The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially. For the convenience of description, the two emitted laser beams are referred to as the adjacent first laser beam and the second laser beam. Figure 3 As shown, Figure 3 It is a schematic diagram of the receiving and analyzing area of ​​the first laser beam and the second laser beam emitted by the laser radar. After the emission time T1 of the first laser beam, t1_overlap is the overlapping area of ​​the receiving and analyzing area of ​​the first laser beam and the last emitted laser beam, and t1_freq is the interval between the emission time T1 and the emission time T2 of the second laser beam. After T2, t2_overlap is the overlapping area of ​​the receiving and analyzing area of ​​the first laser beam and the second laser beam, and t2_freq is the interval between the emission time T2 and the emission time T3 of the next main laser beam. After the emission time T3 of the third laser beam L3, t3_overlap is the overlapping area of ​​the receiving and analyzing area of ​​the second laser beam and the third laser beam.

[0061] Among them, the time intervals between any two adjacent emission of the multiple main laser beams are different, for example, Figure 3The t1_freq and t2_freq shown are different. There are multiple ways to achieve the change of the transmission time interval. For example, the transmitter in the transceiver module is provided with a transmission period T and a randomly generated offset duration, and the offset durations corresponding to any two adjacent main laser beams are different. The offset duration can be a positive value or a negative value, and the actual transmission time interval is determined by controlling the transmitter to add the offset duration to the transmission period T. For another example, the transmitter in the transceiver module is provided with a transmission period T, and the different durations of the intervals between two adjacent transmissions are achieved by controlling the transmitter to regularly increase or decrease a fixed duration based on the transmission period T within a period of time.

[0062] S202, when the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam, the candidate flight times of the first echo are determined according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo.

[0063] When the laser radar transceiver module receives the first echo, the receiving time of the echo is obtained. Figure 3 When the receiving time of the first echo is after the emission of the second laser beam at time T2 and before time T3, if the receiving time of the first echo falls after t2_overlap and before time T3, the first echo does not fall into the overlapping area of ​​any receiving and analysis area, and it can be determined that the first echo is the echo reflected by the object after the second laser beam is emitted. The flight time of the first echo can be calculated based on the receiving time of the first echo and the emission time of the second laser beam.

[0064] When the reception time of the first echo falls into the overlap area t2_overlap, it is necessary to determine which beam of the first laser beam and the second laser beam the first echo is from. Specifically, two candidate flight times of the first echo can be calculated based on the times T1 and T2 and the reception time of the first echo.

[0065] S203: Obtain similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo.

[0066] During the scanning process of the laser radar, due to sufficient scanning density, it is highly likely that multiple adjacent echoes are reflected by the same object, so the real flight times of multiple adjacent echoes are similar. The real flight time of the first echo can be determined by calculating the similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo.

[0067] When calculating the similarity of the flight time between the first echo and an adjacent echo, if the adjacent echo also has at least two candidate flight times, the similarity between each candidate flight time of the first echo and each candidate flight time of the adjacent echo can be calculated. For example, the candidate flight times of the first echo are t1_cand and t2_cand, and the candidate flight times of an adjacent echo are t3_cand and t4_cand. Then, the similarity between t1_cand and t3_cand and t4_cand, and the similarity between t2_cand and t3_cand and t4_cand, are calculated.

[0068] Alternatively, if the adjacent echo used for calculation is received before the first echo and the corresponding real flight time has been obtained according to the adjacent echo, the similarity between each candidate flight time of the first echo and the real flight time corresponding to the adjacent echo can be calculated.

[0069] S204: Determine a real flight time of the first echo from each candidate flight time of the first echo according to the similarity.

[0070] The difference between the candidate flight times of the first echo is the interval between time T1 and T2, and the difference between the candidate flight times of adjacent echoes is also the interval between two adjacent transmissions. Since the real flight time of the first echo and the adjacent echo are similar or the same, and the interval between two adjacent transmissions is different, the similarity between t1_cand and t2_cand, and between t3_cand and t4_cand, is higher than the similarity between the real flight time and the false flight time, and higher than the similarity between the two false flight times. Therefore, the real flight time of the first echo can be determined from the candidate flight times of the first echo according to the similarity.

[0071] Optionally, the similarities may be sorted in order, wherein the two values ​​with the highest similarity are the real flight time corresponding to the first echo and the adjacent echo.

[0072] Optionally, it can be determined whether each similarity is greater than a preset threshold. When there is a similarity less than the preset threshold, the candidate flight time of the first echo corresponding to the similarity less than the preset threshold is determined to be the true flight time of the first echo. In practical applications, there may be a situation where the first echo and the previous adjacent echo are not echoes reflected by the same object. For example, the first echo may be caused by optical noise. In one example, when there is no similarity less than the preset threshold, the first echo is determined to be noise.

[0073] There are many methods for calculating the similarity. For example, the similarity is calculated by calculating the difference between two flight times. Then, the similarity being greater than a preset threshold means that the difference is less than a preset value.

[0074] Optionally, the preset threshold is fixed. Or, the preset threshold is different in different scenarios. For example, the detection method provided in the embodiment of the present application also includes: adjusting the preset threshold according to the ambient light noise of the laser radar and / or the movement speed of the laser radar. For example, the preset threshold is provided with several different (for example, 2, 3 or 4) gears, corresponding to different laser radar movement speed ranges, or corresponding to different ambient light noises (for example, the ambient light noise during the day and at night is different). The laser radar selects the preset threshold corresponding to the gear according to the current movement speed or the current ambient light noise.

[0075] In the embodiment of the present application, by setting the receiving and analysis areas of the main laser light beams emitted for at least two times to be at least partially overlapped, it is possible to achieve a high range while taking into account a high point frequency, but it will cause the echoes received in the overlapping area of ​​the receiving and analysis area to calculate at least two flight times, including a real flight time and a false flight time; based on the assumption that adjacent received echoes are most likely reflected by the same object, the real flight times corresponding to adjacent echoes remain unchanged or approximate, and at the same time, by changing the duration of the interval between two adjacent emissions, the false flight times corresponding to adjacent echoes have a certain gap, so the real flight time can be identified from the similarity between each flight time calculated by the echo and the flight time of at least one adjacent echo.

[0076] Optionally, the adjacent echo used to compare the flight time similarity with the first echo in S203 may be an echo before the first echo, or may be at least two echoes before the first echo, so that the accuracy of the calculation can be improved compared with comparing with only one echo. Optionally, the adjacent echo used to compare the flight time similarity with the first echo in S203 may be one or at least two echoes after the first echo. During the laser radar scanning process, the first echo and the previous echo may be reflected by different objects. Due to the continuity of the scanning, the first echo may be reflected by the same object as the next echo. Optionally, the adjacent echoes used for comparison may include at least one echo before and after the first echo at the same time. Optionally, the number of adjacent echoes used for comparison is 3 or 4, so as to take into account both the accuracy and complexity of the calculation.

[0077] In step S203, in the case of using two candidate flight times of at least one adjacent echo when calculating the similarity, obtaining the similarity includes obtaining a first similarity and a second similarity, wherein the first similarity refers to the similarity between the larger candidate flight time of the first echo and the larger candidate flight time of at least one adjacent echo, and the second similarity refers to the similarity between the smaller candidate flight time of the first echo and the smaller candidate flight time of at least one adjacent echo.

[0078] In one example, the adjacent echoes corresponding to the first similarity and the second similarity are the same adjacent echo. Optionally, when obtaining the similarity, the candidate flight times are not sorted in size, and the similarities between various combinations are directly obtained, such as the similarities of t1_cand with t3_cand and t4_cand described above, and the similarities of t2_cand with t3_cand and t4_cand, respectively. Optionally, when obtaining the similarity, the candidate flight times are first sorted in size, and t1_cand is greater than t2_cand, and t3_cand is greater than t4_cand. Then only the similarity between t1_cand and t3_cand (that is, the first similarity) and the similarity between t2_cand and t4_cand (that is, the second similarity) are calculated.

[0079] In one example, the adjacent echoes corresponding to the first similarity and the second similarity are not the same adjacent echoes. Figure 4 As shown, Figure 4It is a schematic diagram of an embodiment of the receiving and analyzing area of ​​the main laser beam emitted by the laser radar. When calculating the similarity, the receiving and analyzing area is used as the data acquisition window. For the current receiving and analyzing area n, its starting part and the previous receiving and analyzing area n-1 have an overlapping area t1_overlap, and its ending part and the next receiving and analyzing area n+1 have an overlapping area t2_overlap. When echo 1 is received in the overlapping area t1_overlap, the echo 1 corresponds to two candidate flight times, namely t_dis_a_1 (echo 1 receiving time-this main laser beam emission time T1) and t_dis_a_2 (echo 1 receiving time-last main laser beam emission time T0). Since two adjacent echoes are likely to hit the same object, it is highly likely that echo 2 is received in the overlapping area t2_overlap, and the echo 2 corresponds to two candidate flight times, namely t_dis_b_1 (echo 2 receiving time-this main laser beam emission time T2) and t_dis_b_2 (echo 2 receiving time-last main laser beam emission time T1). When calculating the similarity, the similarity between t_dis_a_1 and t_dis_b_1 and t_dis_b_2 is calculated, and the similarity between t_dis_a_2 and t_dis_b_1 and t_dis_b_2 is calculated. Alternatively, when obtaining the similarity, the candidate flight times are first sorted by size, and t_dis_a_1 is smaller than t_dis_a_2, and t_dis_b_1 is smaller than t_dis_b_2. Then only the similarity between t_dis_a_1 and t_dis_b_1 (i.e., the second similarity) and the similarity between t_dis_a_2 and t_dis_b_2 (i.e., the first similarity) are calculated.

[0080] In one example, between two adjacent transmissions of the main laser beam emitted multiple times in step S201, the laser radar also emits a secondary laser beam, and the receiving and analyzing area of ​​the secondary laser beam is shorter than the receiving and analyzing area of ​​the main laser beam. In order to achieve full coverage scanning of the near-range field of view and the long-range field of view, the laser radar adjusts the transmission power of the transceiver module so that the transmission power of the secondary laser beam is less than the transmission power of the main laser beam. The receiving and analyzing area of ​​the secondary laser beam is covered by the receiving and analyzing area of ​​the main laser beam emitted last time. Optionally, the secondary laser beam may overlap with the receiving and analyzing area of ​​the last emitted laser beam and / or the detection time of the main laser beam emitted next time. In this way, there will be an overlap of the receiving and analyzing areas of three laser beams (two main laser beams and one secondary laser beam). Then the echo received in the overlapping receiving and analyzing area will obtain three candidate flight times. When calculating the similarity, it is necessary to calculate the similarity of the three candidate flight times with the flight time of the adjacent echoes respectively, and confirm the real flight time from the three candidate flight times according to the similarity.

[0081] In the optical path of the laser radar, a small part of the energy of the outgoing laser emitted by the laser will directly reach the receiver in the transceiver module through the stray path (i.e., stray light). The echo laser received by the receiver includes stray light and the reflected laser returned after the outgoing laser is reflected. After receiving the stray light, the receiver will excite a certain number of single-photon units and output a photocurrent signal, i.e., the leading signal. The real reflected laser returned after the target object at a close distance reaches the receiver faster, and its photocurrent signal (reflection signal) will be superimposed on the leading signal and cannot be identified, resulting in detection failure. In actual work, the greater the power of the outgoing light, the greater the energy of the stray light, and the longer the quenching time of the leading signal. The stray light directly causes the receiver to saturate in advance and cannot respond to the reflected laser for close-range detection, thereby causing the near-field blind area of ​​the laser radar. The emission power of the main laser and the secondary laser are different, and the corresponding ranging range and near-field blind area are different. In the same detection cycle, the detection results of the main laser and the detection results of the secondary laser are spliced ​​and fused to obtain the point cloud data for the entire ranging range. For example, the secondary detection cycle detects the near-field area of ​​0 to 20m to obtain the secondary detection result; if the main laser adopts the long-distance working mode at this time, the main detection cycle detects the far-field area of ​​15 to 200m to obtain the main detection result; after splicing and fusing the two sets of detection results, point cloud data covering 0 to 200m is obtained, thereby eliminating the near-field blind spot of laser detection.

[0082] In one example, to reduce computational complexity, the detection time of the secondary laser beam can be made to overlap only with the receiving and analyzing area of ​​the last emitted main laser beam, that is, the receiving and analyzing area of ​​the secondary laser beam is staggered with the receiving and analyzing areas of other laser beams except the last emitted main laser beam. Specifically, Figure 5 As shown, Figure 5 FIG. 1 is a schematic diagram of an embodiment of a receiving and analyzing area of ​​a primary laser beam and a secondary laser beam emitted by a laser radar. Figure 3 The difference is that at the time S1 between the emission times T1 and T2, the secondary laser beam s1 is emitted, and the duration of its receiving and analyzing area m is s1_overlap, which is completely located in the receiving and analyzing area n of the first laser beam, and does not overlap with the time T2. Between the main laser beams emitted at the emission times T2 and T3, the secondary laser beam s2 is emitted at the time S2, and the duration of its receiving and analyzing area m+1 is s2_overlap, which is completely located in the receiving and analyzing area n+1 of the second laser beam, and does not overlap with the time T3.

[0083] The laser radar also receives the second echo. When the second echo is located in the receiving and analyzing area m of the secondary laser beam s1, the candidate flight times of the second echo are determined according to the emission time T1 of the first laser beam and the emission time S1 of the secondary laser beam s1 and the receiving time of the second echo. The laser radar also obtains the similarity between the second echo and at least one adjacent echo of the second echo. Specifically, the similarity between the second echo and at least one adjacent echo of the second echo includes the similarity between the candidate flight times of the second echo and the flight time of the at least one adjacent echo. The true flight time of the second echo is determined from the candidate flight times of the second echo according to the similarity. When the second echo is located in the receiving and analyzing area of ​​the first laser beam L1 and is not located in the receiving and analyzing area of ​​other beams, the flight time of the second echo is calculated according to the receiving time and time T1 of the second echo.

[0084] Optionally, since the emission powers of the main laser beam and the secondary laser beam are different, the waveforms of the reflected echoes are different when reflected by the same object, and the waveforms may include at least one of the broadening, peak value, and energy of the echoes. Therefore, the similarity between the second echo and at least one adjacent echo may also be the similarity between the waveform of the second echo and the waveform of at least one adjacent echo, so as to determine whether the second echo is the echo of the main laser beam or the echo of the secondary laser beam.

[0085] Optionally, when calculating the similarity between the second echo and at least one adjacent echo, the at least one adjacent echo may include an echo located in a receiving and analyzing region of an adjacent primary laser beam and / or an echo located in a receiving and analyzing region of an adjacent secondary laser beam.

[0086] In one example, for any two adjacent secondary laser beams, the emission time interval of one secondary laser beam from the main laser beam emitted last time is different from the emission time interval of another secondary laser beam from the main laser beam emitted last time. Alternatively, the emission reference time interval of one secondary laser beam from the main laser beam emitted last time is different from the emission reference time interval of another secondary laser beam from the main laser beam emitted last time, and the emission time of the main laser beam is obtained by increasing or decreasing the random interval according to the emission reference time. When calculating the similarity between the second echo and at least one adjacent echo, the similarity includes the similarity of each candidate flight time of the second echo and the flight time of at least one adjacent echo. If the second echo is the echo of the secondary laser beam, and the echoes in the receiving and analyzing areas of the two adjacent secondary laser beams are likely to hit the same object and have similar real flight times, the false flight time can be changed by changing the emission time interval of the secondary laser beam from the main laser beam emitted last time. Therefore, according to the similarity of each candidate flight time of the second echo and the flight time of at least one adjacent echo, the real flight time of the second echo can be identified.

[0087] In an example, Figure 5 As shown, for the receiving and analyzing area n of the main laser beam emitted at time T1, its starting part and the receiving and analyzing area n-1 of the previous main laser beam have an overlapping area t1_overlap, its ending part and the receiving and analyzing area n+1 of the next main laser beam have an overlapping area t2_overlap, and its middle part and the receiving and analyzing area m of the secondary laser beam emitted at time S1 have an overlapping area s1_overlap. When the echo a reflected by the object within the near-field distance is received in the overlapping area s1_overlap, since the two adjacent echoes are likely to hit the same object, it is likely that the echo b is also received in the overlapping area t1_overlap, and the echo c is also received in the overlapping area t2_overlap, and the echo d and echo e are also received in the receiving and analyzing areas m-1 and m+1 of the adjacent secondary laser beams, respectively. Each echo has two candidate flight times, and the echo used to calculate the similarity with the echo a can have at least one of the following echoes: echo b, echo c, echo d, and echo e.

[0088] The method for calculating the similarity of echo a and the method for determining the true flight time according to the similarity may refer to the method for calculating the similarity of the first echo and the method for determining the true flight time according to the similarity, which will not be described in detail here.

[0089] In one example, the above-mentioned laser radar detection method (that is, the method of overlapping the receiving and analysis areas of adjacent light beams) can be selected to be turned on or off. For example, the laser radar is installed on a moving object (such as a car) and receives instructions from a control system on the moving object. The instruction can instruct the laser radar to choose to turn on or off the above-mentioned laser radar detection method. For example, in a long-distance detection scenario, such as a car on a highway, the laser radar can automatically or according to the received instructions turn on the function of overlapping the receiving and analysis areas, and execute the above-mentioned laser radar detection method; in some close-range detection scenarios, the laser radar does not require a very high detection point frequency, and can automatically or according to the received instructions turn off the function of overlapping the receiving and analysis areas, and does not execute the above-mentioned laser radar detection method.

[0090] The present application also provides a laser radar, such as Figure 6 As shown, Figure 6 It is a schematic diagram of an embodiment of the laser radar in the embodiment of the present application. The laser radar 60 includes a transceiver module 61 and a processing module 62. The transceiver module 61 includes a transmitter 611 for emitting a main laser beam multiple times. The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially; the intervals between any two adjacent emission of the multiple main laser beams are different; the laser beams emitted at least twice include a first laser beam and a second laser beam emitted adjacent to the first laser beam. The transceiver module 61 also includes a receiver 612, and the continuous opening state time of the receiver 612 corresponds to the receiving and analyzing area of ​​each main laser beam emitted by the transmitter 611, so as to receive the echo (if any) of the main laser beam in the receiving and analyzing area of ​​a main laser beam. Specifically, the receiver is used to receive the first echo. The processing module 62 is used to determine the candidate flight times of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo, respectively, when the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam, obtain the similarity between the candidate flight times of the first echo and the flight time of at least one adjacent echo of the first echo, and determine the real flight time of the first echo from the candidate flight times of the first echo according to the similarity. With respect to the device in the above embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment of the method, and will not be described in detail here.

[0091] The present application also provides a laser radar, such as Figure 7 As shown, Figure 7 Schematic diagram of an embodiment of a laser radar in the embodiment of the present application. The electronic device 70 includes a memory 71 and a processor 72 .

[0092] The processor 72 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0093] The memory 71 may include various types of storage units, such as system memory, read-only memory (ROM) and permanent storage devices. Among them, ROM can store static data or instructions required by the processor 72 or other modules of the computer. The permanent storage device can be a readable and writable storage device. The permanent storage device can be a non-volatile storage device that will not lose the stored instructions and data even if the computer is powered off. In some embodiments, the permanent storage device uses a large-capacity storage device (such as a magnetic or optical disk, flash memory) as a permanent storage device. In some other embodiments, the permanent storage device can be a removable storage device (such as a floppy disk, an optical drive). The system memory can be a readable and writable storage device or a volatile readable and writable storage device, such as a dynamic random access memory. The system memory can store some or all instructions and data required by the processor at run time. In addition, the memory 61 can include any combination of computer-readable storage media, including various types of semiconductor storage chips (such as DRAM, SRAM, SDRAM, flash memory, programmable read-only memory), and disks and / or optical disks can also be used. In some embodiments, the memory 510 may include a readable and / or writable removable storage device, such as a laser disc (CD), a read-only digital versatile disc (such as a DVD-ROM, a double-layer DVD-ROM), a read-only Blu-ray disc, an ultra-density optical disc, a flash memory card (such as an SD card, a mini SD card, a Micro-SD card, etc.), a magnetic floppy disk, etc. The computer-readable storage medium does not include carrier waves and transient electronic signals transmitted wirelessly or wired.

[0094] The memory 71 stores executable codes, and when the executable codes are processed by the processor 72 , the processor 72 can execute part or all of the methods described above.

[0095] In addition, the method according to the present application may also be implemented as a computer program or a computer program product, which includes computer program code instructions for executing some or all of the steps in the above method of the present application.

[0096] Alternatively, the present application can also be implemented as a computer-readable storage medium (or non-transitory machine-readable storage medium or machine-readable storage medium) on which executable code (or computer program or computer instruction code) is stored. When the executable code (or computer program or computer instruction code) is executed by a processor of an electronic device (or server, etc.), the processor executes part or all of the steps of the above-mentioned method according to the present application.

[0097] The embodiments of the present application have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A laser radar detection method, characterized in that: include: Fire the main laser beam multiple times, The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially, and the receiving and analyzing areas of the main laser beams take the emission time of the main laser beams as a starting point and the flight time corresponding to the maximum detection distance of the main laser beams as a duration; Wherein, the time intervals between any two adjacent emissions of the multiple main laser beams are different; Wherein, the main laser beams emitted at least twice include adjacent first laser beams and second laser beams; Receive the first echo; When the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam, determining candidate flight times of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo, respectively; obtaining similarities between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo, The actual flight time of the first echo is determined from the candidate flight times of the first echo according to the similarity.

2. The method according to claim 1, characterized in that The at least one adjacent echo of the first echo includes at least one adjacent echo received before the first echo, or includes at least one adjacent echo received before and at least one adjacent echo received after the first echo.

3. The method according to claim 1, characterized in that The determining the true flight time of the first echo from each candidate flight time of the first echo according to the similarity comprises: When there is a similarity smaller than a preset threshold, the candidate flight time of the first echo corresponding to the similarity smaller than the preset threshold is determined as the actual flight time of the first echo.

4. The method according to claim 3, characterized in that When there is no similarity less than the preset threshold, the first echo is determined as noise.

5. The method according to claim 3, characterized in that: The method further comprises: The preset threshold is adjusted according to the ambient light noise of the laser radar and / or the movement speed of the laser radar.

6. The method according to claim 1, characterized in that in, The multiple main laser beams are emitted in sequence at intervals of an emission period T plus or minus a randomly generated offset duration, and any two adjacent main laser beams have different corresponding offset durations.

7. The method according to claim 1, characterized in that The time of flight of at least one neighboring echo of the first echo includes two candidate times of flight of at least one neighboring echo; The obtaining of similarities between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo includes: obtaining a similarity between a larger candidate flight time of the first echo and a larger candidate flight time of at least one adjacent echo, and A similarity between the smaller candidate flight time of the first echo and the smaller candidate flight time of at least one adjacent echo is obtained.

8. The method according to claim 1, characterized in that The method further comprises: A secondary laser beam is emitted between two adjacent emissions of the multiple emitted main laser beams, and a receiving and analyzing area of ​​the secondary laser beam is located within a receiving and analyzing area of ​​the last emitted main laser beam; receiving a second echo; When the second echo is located within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the sub-laser beam, determining the candidate flight times of the second echo according to the emission time of the first laser beam, the emission time of the sub-laser beam and the receiving time of the second echo; Acquire the similarity between the second echo and at least one adjacent echo of the second echo, including the similarity between each candidate flight time of the second echo and the flight time of at least one adjacent echo of the second echo, and / or the similarity between the waveform of the second echo and the waveform of at least one adjacent echo of the second echo; The actual flight time of the second echo is determined from the candidate flight times of the second echo according to the similarity.

9. The method according to claim 8, characterized in that The receiving and analyzing area of ​​the sub-laser beam is staggered from the receiving and analyzing areas of other laser beams except the adjacent main laser beam emitted last.

10. The method according to claim 8, characterized in that The obtaining of the similarity between the second echo and at least one adjacent echo of the second echo comprises: The similarity between the second echo and at least one echo of the second echo located in a receiving and analyzing area of ​​an adjacent main laser beam is acquired.

11. The method according to claim 10, characterized in that For any two consecutively emitted sub-laser beams, the emission time interval between one of the sub-laser beams and the last emitted main laser beam is different from the emission time interval between another sub-laser beam and the last emitted main laser beam; The obtaining of the similarity between the second echo and at least one adjacent echo of the second echo comprises: The similarity between each candidate flight time of the second echo and the flight time of at least one echo of the second echo located in the receiving and analyzing area of ​​the adjacent sub-laser beam is obtained.

12. A laser radar, characterized in that: include: The transceiver module is used to transmit the main laser beam multiple times. The receiving and analyzing areas of at least two emitted main laser beams overlap at least partially, and the receiving and analyzing areas of the main laser beams take the emission time of the main laser beams as a starting point and the flight time corresponding to the maximum detection distance of the main laser beams as a duration; Wherein, the time intervals between any two adjacent emissions of the multiple main laser beams are different; Wherein, the at least twice emitted laser beams include a first laser beam and a second laser beam emitted adjacent to and after the first laser beam; The transceiver module is also used to receive the first echo; A processing module is used to determine each candidate flight time of the first echo according to the emission time of the first laser beam, the emission time of the second laser beam and the reception time of the first echo, respectively, when the first echo is received within the overlapping area of ​​the receiving and analyzing areas of the first laser beam and the second laser beam; obtain the similarity between each candidate flight time of the first echo and the flight time of at least one adjacent echo of the first echo, and determine the real flight time of the first echo from the candidate flight times of the first echo according to the similarity.

13. A laser radar, characterized in that: include: processor; as well as A memory having executable codes stored thereon, which, when executed by the processor, causes the processor to execute the method according to any one of claims 1 to 11.

14. A computer-readable storage medium having executable codes stored thereon, which, when executed by a processor of an electronic device, causes the processor to execute the method according to any one of claims 1 to 11.

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