WO2022105273A1 - 激光雷达的控制方法及激光雷达 - Google Patents

激光雷达的控制方法及激光雷达 Download PDF

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Publication number
WO2022105273A1
WO2022105273A1 PCT/CN2021/106707 CN2021106707W WO2022105273A1 WO 2022105273 A1 WO2022105273 A1 WO 2022105273A1 CN 2021106707 W CN2021106707 W CN 2021106707W WO 2022105273 A1 WO2022105273 A1 WO 2022105273A1
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Prior art keywords
laser beam
detection
lasers
detection laser
lidar
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PCT/CN2021/106707
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English (en)
French (fr)
Inventor
梁峰
向少卿
时从波
周小童
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上海禾赛科技有限公司
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Publication of WO2022105273A1 publication Critical patent/WO2022105273A1/zh
Priority to US18/145,333 priority Critical patent/US20230129970A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/4802—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/484—Transmitters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/08—Systems determining position data of a target for measuring distance only
    • G01S17/10—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves
    • G01S17/26—Systems determining position data of a target for measuring distance only using transmission of interrupted, pulse-modulated waves wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/42—Simultaneous measurement of distance and other co-ordinates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G01S17/06—Systems determining position data of a target
    • G01S17/46—Indirect determination of position data
    • G01S17/48—Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4814—Constructional features, e.g. arrangements of optical elements of transmitters alone
    • G01S7/4815—Constructional features, e.g. arrangements of optical elements of transmitters alone using multiple transmitters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4861—Circuits for detection, sampling, integration or read-out
    • G01S7/4863—Detector arrays, e.g. charge-transfer gates
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers
    • G01S7/4865—Time delay measurement, e.g. time-of-flight measurement, time of arrival measurement or determining the exact position of a peak
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/497—Means for monitoring or calibrating

Definitions

  • the present disclosure relates to the technical field of photoelectric detection, and in particular, to a control method and a laser radar for reducing the luminous intensity of a laser radar without reducing the short-range detection capability.
  • LiDAR is a general term for laser active detection sensor equipment. Its working principle is roughly as follows: the transmitter of the lidar emits a beam of laser light. After the laser beam encounters an object, it is diffusely reflected and returned to the laser receiver. The radar module The distance between the transmitter and the object can be calculated by multiplying the time interval between sending and receiving signals by the speed of light and dividing by 2. Depending on the number of laser beams, there are usually single-line lidar, 4-line lidar, 8/16/32/64-line lidar, etc. The higher the wire harness, the more complex the structure of the lidar and the higher the integration. For a highly integrated lidar, electrical power consumption needs to be reduced as much as possible.
  • lidar In many actual installation and use processes, there may be some intentionally set obstructions close to the lidar. For example, some wiring harnesses are blocked by the vehicle body at certain horizontal angles; for example, only part of the lidar is used. The detection range of the angle, other angles are blocked. At the same time, in the use environment of lidar, some targets often appear in places very close to the radar (for example, ⁇ 3m). The detection of these close-range targets can be achieved without excessive detection light intensity, thereby saving power consumption. In some lidar solutions, according to the detection results of lidar, if an object is detected nearby, the luminous light intensity will be reduced when scanning to the same angular range next time, and only meet the light intensity requirements of near measurement, thereby reducing the luminous intensity. power consumption. But this strategy, while reducing the luminous intensity, may create situations where nearby objects cannot be detected.
  • the emitted light intensity is very high during the first detection, and there is an object detected nearby; as shown in Fig. 1B, when the angular range of the nearby object is scanned for the second time, the emitted light intensity is reduced, but It is possible that the echo intensity reflected by the near object does not reach the threshold Th, so that the near object cannot be detected in the second scan. Therefore, although the power consumption is reduced, the ability of close-range detection is weakened or even lost.
  • Figure 1C explains why the non-coaxial transceiving lidar reduces power consumption while at the same time degrading or even losing its short-range detection capability.
  • a laser and a detector that match the remote field of view of the lidar form a channel, as shown in Figure 1C, for channel A and channel B of the lidar, when the lidar is used to detect distant objects , after the detection laser beam L0 emitted by the laser of channel A is reflected by the distant object OB1, the radar echo is close to parallel light, and will be irradiated on the detector D1 of channel A, as shown in the upper left of Figure 1C, this is an ideal situation.
  • the lidar When the lidar is used to detect objects near OB2, after the detection laser beam L0 emitted by the laser in channel A is reflected by the near target, the radar echo cannot be approximated as parallel light, and when it reaches the focal plane where the detector is located When the spot shift and dispersion occur, it will illuminate D2 on the channel B detector next to the channel A detector, as shown in the lower left of Figure 1C.
  • the shift and dispersion of the light spot will cause optical crosstalk between lidar channels , the shift and dispersion of the light spot become more obvious with the distance, so the more lines used for the detection of short-range targets, the more influence on the ranging accuracy and accuracy of the lidar.
  • the traditional method adopts the solution of combined distance and near-measuring radars, one of which is dedicated to measuring distant objects.
  • another radar is specialized to measure near objects, so although it can improve the short-range measurement performance, it increases the system cost, the difficulty of installation and debugging.
  • the invention provides a control method and a laser radar for reducing the luminous intensity of a laser radar on the basis of not weakening the short-range detection capability.
  • the present invention provides a control method for a laser radar, wherein the laser radar includes a laser array with N lasers, and the control method includes:
  • S301 Control n lasers to emit a first detection laser beam, and control k lasers to emit a second detection laser beam; wherein n ⁇ N, the k lasers are selected from the n lasers, k ⁇ n, the The light intensity of the first detection laser beam is greater than the light intensity of the second detection laser beam;
  • S302 Receive echoes reflected by the first detection laser beam and the second detection laser beam on the target;
  • the step S304 includes: obtaining the angular range of the target object within a preset distance according to the distance of the target object, and reducing the angular range of the n lasers within the angular range The laser emits the luminous intensity of the first detection laser beam in the next detection period.
  • the step S304 includes: obtaining the angular range of the target within the preset distance according to the distance of the target, and turning off the n lasers in the next detection cycle Part of the laser within the stated angular range.
  • p lasers and one detector form a detection channel, p ⁇ 1
  • the step S304 includes: when one of the detection channels detects a target within a preset distance, controlling the detection The laser of the detection channel within a preset range around the channel reduces the luminous intensity of the first detection laser beam emitted in the next detection period.
  • the preset range is divided according to a midline between two near-point clouds.
  • the step S304 includes: correcting the angular range in the next detection period according to one or more of the target type, motion parameters, and detection parameters of the lidar.
  • the first detection laser beam is used to measure a target at a longer distance, and the N lasers are divided into m groups to emit light sequentially, m is an integer and m>1, the step S301 includes:
  • the k lasers in the laser array are controlled to emit a second probe laser beam before or after the first probe laser beam is emitted.
  • the first detection laser beam and the second detection laser beam have different pulse codes
  • the step S303 includes: according to different pulse codes, determining that the echo corresponds to the first detection laser beam or the second detection laser beam, and according to the time point at which the first detection laser beam or the second detection laser beam is emitted , calculate the distance of the target object.
  • the step S303 includes:
  • the echo corresponds to the first detection laser beam or the second detection laser beam, and according to the time point at which the first detection laser beam or the second detection laser beam was emitted, calculate the distance of the target.
  • the step S303 includes:
  • the possible distances between the target object and the lidar are calculated respectively;
  • the echo signal corresponds to the first detection laser beam or the second detection laser beam, and the distance of the target object is determined.
  • the present invention also provides a laser radar, comprising:
  • a laser array with N lasers configured to emit a probe laser beam
  • a receiving unit including a detector array, capable of receiving echoes of the detection laser beam reflected on the target and converting them into electrical signals;
  • the control unit coupled to the laser array and the receiving unit, is configured to calculate the distance of the target object according to the electrical signal, and can control the n lasers to emit a first detection laser beam, and control the k lasers to emit a first detection laser beam.
  • the control unit is configured to: when a target object is detected within a preset distance, in the next detection period, within a range corresponding to the target object, at least part of the lasers in the n lasers are reduced to emit a first detection laser beam luminous intensity.
  • control unit is configured to: obtain an angular range of the target within a preset distance according to the distance of the target, and reduce the angular range of the n lasers within the angular range
  • the inner laser emits the luminous intensity of the first detection laser beam in the next detection period.
  • control unit is configured to: obtain the angular range of the target within the preset distance according to the distance of the target, and turn off the n lasers in the next detection period
  • the emission of the part of the laser within the angular range is the emission of the first detection laser beam.
  • p lasers and one detector form a detection channel, p ⁇ 1
  • the control unit is configured to: when one of the detection channels detects a target within a preset distance, control the The laser of the detection channel within a preset range around the detection channel is used to reduce the luminous intensity of the first detection laser beam emitted in the next detection period.
  • the preset range is divided according to a midline between two near-point clouds.
  • control unit is configured to: obtain the angular range of the target object within the preset distance according to the distance of the target object output by the control unit, and reduce the angular range of the target object within the angular range and The laser within a preset range adjacent to the angular range measures the luminous intensity of the telephoto mode in the next detection period.
  • control unit is configured to: modify the angular range in the next detection period according to one or more of the type of the target, motion parameters, and detection parameters of the lidar .
  • the first detection laser beam is used to measure a target at a longer distance
  • the N lasers are divided into m groups to emit light sequentially, m is an integer and m>1
  • the control unit is configured to: at each horizontal angular position of the lidar, control the n lasers in each group of laser arrays to emit a first detection laser beam; at the same level At an angular position, the k lasers in the laser array are controlled to emit a second probe laser beam either before or after the first probe laser beam is emitted.
  • the first detection laser beam and the second detection laser beam have different pulse codes
  • the control unit is configured to: determine that the echo corresponds to the first detection laser beam or the second detection laser beam according to different pulse codes, and according to the time when the first detection laser beam or the second detection laser beam is emitted point to calculate the distance to the target.
  • control unit is configured to: determine that the echo corresponds to the first detection laser beam or the second detection laser beam by receiving the time window of the echo, and to transmit the first detection laser beam according to the time window.
  • the time point of the detection laser beam or the second detection laser beam is calculated, and the distance of the target object is calculated.
  • control unit is configured to: calculate the possible distance between the target and the lidar according to the detected echoes and the time points at which the first detection laser beam and the second detection laser beam are emitted, respectively. ; determine that the echo signal corresponds to the first detection laser beam or the second detection laser beam, and determine the distance of the target object.
  • the present invention also provides a computer-readable storage medium comprising computer-executable instructions stored thereon, the executable instructions, when executed by a processor, implement the control method as described above.
  • FIGS. 1A and 1B are schematic diagrams showing the strategy of reducing the luminous intensity when there is an object in the vicinity adopted by the lidar;
  • Figure 1C explains the reduction in power consumption while at the same time weakening or even losing the ability to detect close range
  • FIG. 2 shows a schematic diagram of a transmitting unit of a lidar according to an embodiment of the present invention
  • FIG. 3 shows a schematic diagram of a laser array according to an embodiment of the present invention
  • Fig. 4A shows the trajectories swept by each laser beam of the lidar on a distant target
  • Figure 4B shows a schematic diagram of the stacking and redundancy of the laser light spot on the near target
  • FIG. 5 shows a logical arrangement (light-emitting timing) of a plurality of lasers of a laser array according to an embodiment of the present invention
  • FIG. 6 shows the light-emitting timings of the first mode and the second mode according to an embodiment of the present invention
  • FIG. 7 shows the light-emitting timings of the first mode and the second mode according to another embodiment of the present invention.
  • FIG. 8 shows the logical arrangement (light-emitting timing) of the laser array at adjacent horizontal angular positions according to one embodiment of the present invention
  • FIG. 9 shows a schematic diagram of a lidar according to an embodiment of the present invention.
  • FIG. 10A shows a schematic diagram of a method for ranging by using a lidar according to an embodiment of the present invention
  • FIG. 10B shows a schematic diagram of a method for ranging by using a lidar according to another embodiment of the present invention.
  • FIG. 11 shows a flowchart of a control method for a lidar according to an embodiment of the present invention
  • Fig. 12a shows a schematic diagram of the luminous intensity of the lidar according to the second aspect of the present invention
  • Figure 12b shows a schematic diagram of a lidar point cloud using the scheme of Figure 12a;
  • FIG. 13a and 13b show schematic diagrams of the first detection and the second detection of the lidar according to an embodiment of the present invention
  • FIG. 14 shows a working method of a lidar according to an embodiment of the present invention
  • FIG. 15 shows a schematic diagram of the division of the influence domain according to an embodiment of the present invention.
  • Figure 16 shows a schematic diagram of detection with reduced horizontal angular resolution according to one embodiment of the present invention.
  • FIG. 17 shows a schematic diagram of detection for reducing vertical angular resolution according to an embodiment of the present invention.
  • connection should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection: it can be a mechanical connection, an electrical connection or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction of two elements relation.
  • connection should be understood in a broad sense, for example, it may be a fixed connection or a detachable connection Connection, or integral connection: it can be a mechanical connection, an electrical connection or can communicate with each other; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction of two elements relation.
  • a first feature "on” or “under” a second feature may include direct contact between the first and second features, or may include the first and second features Not directly but through additional features between them.
  • the first feature being “above”, “over” and “above” the second feature includes that the first feature is directly above and diagonally above the second feature, or simply means that the first feature is level higher than the second feature.
  • the first feature “below”, “below” and “beneath” the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature has a lower level than the second feature.
  • a first aspect of the present invention relates to a laser emitting unit, for example, which can be used as a laser radar emitting unit, which will be described in detail below with reference to the accompanying drawings.
  • the transmitting unit 100 includes: a laser array 101 and a control unit 102 .
  • the laser array 101 includes a plurality of lasers, which are arranged on one or more substrates, and each laser can be individually driven and controlled to emit light.
  • FIG. 2 schematically shows a schematic diagram of a plurality of lasers included in the laser array 101 arranged on a substrate (eg, a circuit board).
  • the laser array 101 includes, for example, four columns of lasers, totaling 30 lasers.
  • the present invention is not limited to this, the laser array 101 may include more or less lasers, and the physical arrangement of the lasers can be arbitrarily set as required. multiple substrates, as shown in Figure 3.
  • the emitting unit 100 further includes a emitting lens (not shown) for modulating (collimating) each laser beam emitted by the laser into parallel light and outputting it to the ambient space around the lidar
  • each laser in the laser array 101 is preferably located at different heights on the focal plane of the emission lens, and corresponds to different vertical fields of view after being emitted by the emission lens.
  • FIG. 3 shows a laser array 101 according to another embodiment of the present invention.
  • the laser array 101 includes a plurality of substrates 1012 and lasers 1011 arranged on the respective substrates 1012, wherein each laser 1011 is at a different height of the focal plane of the emission lens, corresponding to a different vertical field of view of the lidar.
  • control unit 102 is coupled to the laser array 101 and configured to control the lasers in the laser array 101 to emit light.
  • the control unit 102 may include a high voltage unit and a logic control unit, wherein the high voltage unit is used to generate the high voltage required to drive the laser to emit light, and the logic control unit is used to control the lighting sequence and logic of the laser array 101 . Details are described below.
  • the lidar of the present invention is angle-triggered, and at each horizontal angular position of the lidar, the lidar completes a complete ranging process.
  • the horizontal angle resolution of the lidar is 0.2°
  • each horizontal angle of the lidar is every 0.2°, starting from 0°, and performing angle triggering at 0°, 0.2°, 0.4°... to complete a complete ranging process.
  • medium and high line-count lidars such as 64 and 128 lines
  • the inventor of the present invention found that: for a high-line beam laser radar, the channels are densely arranged, and the more channels that emit light at the same time, the easier it is to generate optical crosstalk. This kind of crosstalk has an acceptable effect on detecting distant targets, but when measuring near targets, the mutual interference between channels is very serious. From the point cloud point of view, the distance measurement of the target object is inaccurate and the channel consistency is poor.
  • the vertical and horizontal angular resolutions of the high-beam lidar are excessive when all channels are illuminated when detecting close targets.
  • the laser spots scanned on the target can be clearly spaced due to the long distance. Due to the long distance, the laser reflected back to the radar is basically parallel light, and the position of the spot on the focal plane is less affected by the distance, so the scanning of long-distance objects can maximize the use of all channels and maximum performance of the lidar.
  • the radiation divergence distance of the laser beam is short, so the trajectories swept by each laser beam on the target are dense, so there is serious spot stacking and redundancy. Dispersion, that is, wasting the laser beam and affecting the measurement accuracy of the lidar.
  • the control unit 102 is configured to use more lasers to emit light in the first mode to improve the resolution of distant objects; meanwhile, in the second mode, use fewer lasers to emit light.
  • the channel is used to measure the near target, and the simultaneous light-emitting channels are as few as possible, preferably a single channel, in order to reduce the interference between the simultaneous light-emitting channels, so that the accuracy of the near measurement is greatly improved.
  • the first mode includes: controlling n lasers in the laser array 101 to emit light, where n is less than or equal to N, where N is the total number of lasers in the laser array; the second mode includes controlling the lasers The k lasers in the array emit light, wherein the k lasers are selected from the n lasers, and k is less than n.
  • the n is equal to the total number N of lasers in the laser array.
  • the second mode is single-channel emission.
  • the n lasers emit light simultaneously, and the k lasers also emit light simultaneously.
  • the first mode includes: at each horizontal angular position of the lidar, controlling the n lasers in the laser array to emit light; the second mode includes : controlling the k lasers in the laser array to emit light at the same horizontal angular position as the first mode.
  • the horizontal angular resolution of the lidar mentioned above is 0.2°, and each horizontal angle of the lidar is every 0.2°, starting from 0°, and performing angle triggering at 0°, 0.2°, 0.4°... . That is, at each angle of 0°, 0.2°, 0.4°...
  • the laser array 101 performs the light-emitting ranging of the first mode and the second mode.
  • the horizontal angular resolution of the lidar can also be 0.1° or other angles, according to detection needs. Make settings.
  • the above is just an example of including 8 lasers in the laser array 101 to briefly illustrate the first mode and the second mode.
  • the high-line beam lidar can usually reach 40, 64, 128 and higher line numbers, due to the detection distance and horizontal angle resolution. Due to the constraints of the rate, high-beam lidars usually need to emit light in multiple groups in sequence, and each group of laser arrays is a sub-laser array.
  • the laser arrays are divided into m groups to emit light sequentially, m is an integer and m>1, and the control unit is configured to control each group of laser arrays to emit the first detection laser light in a first mode and configured to control each set of laser arrays to emit a second probe laser beam in a second mode before or after emitting a first probe laser beam in the first mode.
  • the m sub-laser arrays all finish emitting light in a pattern.
  • the sequence of the first mode and the second mode of the m sub-arrays is consistent. For example, for the m sub-laser array, the first mode is performed first, and then the second mode is performed.
  • Sequential lighting of m groups means that in chronological order, after one group is completed, the next group of operations is performed.
  • the lasers that emit light in each mode can emit light simultaneously, and the lasers that emit light in the second mode can emit light simultaneously.
  • the lasers emitting in the second mode of part of the sub-laser array may be equal to 0.
  • FIG. 5 shows the logical arrangement (light-emitting sequence) of a plurality of lasers in the laser array 101 , where the laser array 101 includes 128 lasers as an example for description.
  • the 128 lasers can be divided into 16 groups, and each group of 8 lasers emits light at the same time, a total of 16 times, and the emission of 128 lasers can be completed.
  • the horizontal direction in FIG. 5 is the sequence of light-emitting time, and the lasers are divided into 16 groups, each group has 8 lasers.
  • the numbers of the 8 lasers that emit light at the first moment are 1-1, 1-2, ..., 1-7, 1-8
  • the numbers of the 8 lasers that emit light at the 16th moment are 16-1, 16-2, . . . , 16-7, 16-8
  • the lasers that emit light at other times are numbered similarly, and will not be repeated here.
  • the 128 lasers are fired from the same horizontal angle.
  • the laser array 101 is a laser array formed by a single laser or a linear array laser or a surface array laser, and the laser includes an edge emitting laser or a vertical cavity surface emitting laser or a combination of the two.
  • the lasers are numbered and arranged according to the logical order of light emission, which may be consistent with the physical arrangement of the lasers shown in FIGS. 2 and 3 , or may be inconsistent.
  • the two lasers located in the same column in FIG. 2 may be at different light-emitting moments in FIG. 5 , which are all within the protection scope of the present invention.
  • the first mode and the second mode are relative concepts, wherein the number of lasers used in the first mode is greater than the number of lasers used in the second mode.
  • the first mode is a distance measurement mode, using all the lasers in the laser array 101 to emit light alternately for detection;
  • the second mode is a proximity mode, using part of the lasers in the laser array 101 Alternate light for detection.
  • part of the lasers can be used to emit light (that is, n is smaller than N), as long as the number of emitting lasers in the first mode is more than that in the second mode The number of emitting lasers is sufficient.
  • the following description will take the first mode using all lasers to emit light as an example for illustration.
  • the control unit 102 may control the k lasers in the laser array such that the k lasers in the first mode emit a first probe laser beam before or after the first detection laser beam is emitted in a second mode.
  • the mode emits a second probe laser beam.
  • the control unit 102 may pre-set a selection method to select or randomly select the k lasers emitting in the second mode, before or after the k lasers emitting in the first mode, perform an emission according to the second mode.
  • FIG. 5 shows the transmission of the second mode following the transmission of the first mode.
  • the emitting unit including 128 lasers shown in Figure 5 8 lasers are selected, and their numbers are 1-1, 3-1, 4-2, 5-3, 7-4, 9-5, 10- 3. 12-1.
  • the 8 lasers complete the distance measurement and an additional near-measurement emission (the second mode) is added.
  • Figure 6 shows the measurement of one of the lasers.
  • Far emission and near emission in which the green block is the time window for distance emission, and the yellow block is the time window for near emission. Therefore, 8 times of near emission are inserted in the 128 channels of luminous remote measurement in turn.
  • each proximity emission is preferably single-channel emission, that is, only one laser emits in the second mode at the same time.
  • the present invention is not limited to the number of selected partial lasers, 8 lasers are shown in FIG. 5 for emitting the second detection laser beam, and the specific number may be more or less than 8, depending on the desired measurement Near-horizontal angular resolution to decide.
  • the part of the lasers emitted in the second mode may be preset or generated in real time. For example, for the 8 lasers at each light-emitting moment in FIG. 5, one laser may be randomly selected to implement the emission in the second mode, which is within the protection scope of the present invention.
  • Figures 5 and 6 show that for the k lasers, the emission of the second mode follows the emission of the first mode.
  • the transmission in the second mode may also be performed before the transmission in the first mode, as shown in FIG. 7 .
  • the k lasers are firstly emitted according to the second mode, so as to perform near target detection. It will not be repeated here.
  • the distance measurement mode is used (that is, the distance measurement result is used to provide the three-dimensional point cloud data of the radar distance measurement), and the laser emitted by the distance measurement mode is used.
  • the number of lasers is large.
  • the distance between the target and the lidar is within 5m, it is in the proximity mode (that is, the distance measurement results are used to provide the three-dimensional point cloud data of the radar proximity measurement), and the number of lasers emitted by the proximity mode is small.
  • the present invention is not limited to the above-mentioned specific values, and can also be modified and adjusted according to specific conditions.
  • the distance preset value is determined according to the distance-dependent spot shift and dispersion degree obtained by the lens parameters of the laser radar and the system's ability to recognize the output signal of the detector. .
  • the setting of the distance preset value is used as a reference to output the three-dimensional point cloud data of the lidar, which will be described in detail below.
  • the first detection laser beam and the second detection laser beam may have different pulse codes .
  • both the first detection laser beam and the second detection laser beam can use double pulses, but the double pulses of the two have different time intervals for encoding, so that the receiving end can distinguish the echo corresponding to the echo pulse according to the interval of the echo pulse.
  • the first detection laser beam and the second detection laser beam can also use three pulses.
  • the first detection laser beam and the second detection laser beam can also be distinguished by the signals read in different time windows reserved by the detectors corresponding to each channel.
  • the first detection laser beam of the mode is used for distance measurement, then the detector (after the laser in the channel emits light in the first mode) reserves a longer first time window for the echo reception of the first detection laser beam reflected from the target object , after the first mode completes the distance measurement, a shorter second time window is reserved for the echo reception of the second detection laser beam in the second mode proximity measurement, so the first time window and the second time window of each channel detector are passed.
  • the window signal is read to distinguish the first detection laser beam from the second detection laser beam.
  • the time of flight TOF is obtained, which is multiplied by the speed of light c and divided by 2 to obtain the distance between the target and the lidar.
  • the distance measuring mode >3m corresponds to the tof time (time window) of t>20ns
  • the near mode mode, such as ⁇ 3m corresponds to the tof time (time window) corresponding to t ⁇ 20ns.
  • the possible distance between the target object and the lidar can also be calculated separately according to the detected echoes and the time points at which the first detection laser beam and the second detection laser beam are emitted. Then, it is determined that the echo signal corresponds to the first detection beam or the second detection beam (for example, it can be determined according to the expected detection distance corresponding to each detection beam), and the distance of the target object is determined from two possible distances.
  • Lidars usually have an axis of rotation around which they can rotate in a plane.
  • the lidar is installed vertically for description, that is, the rotation axis is along the vertical direction, the lidar can be rotated in the horizontal plane, and during the rotation, the driving laser emits a detection laser beam.
  • the lidar has a certain angular resolution, such as 0.1° or 0.2°, and the detection laser beam is emitted at each horizontal angular position of the lidar (eg, at intervals of the horizontal angular resolution of the lidar).
  • Figure 8 shows the lidar.
  • the angular resolution is 0.1°, that is, every 0.1°, a detection is performed.
  • the first mode includes: at each horizontal angular position of the lidar, controlling the n lasers in the laser array to emit light; the second mode includes: At the same horizontal angular position as the first mode, some of the lasers in the laser array are controlled to emit light.
  • the luminescence detection of the second mode is also performed by the k lasers.
  • the 128 lasers are divided into 16 groups to emit light, and each group of laser arrays (ie, sub-laser arrays) includes 8 lasers.
  • control n lasers in each group of laser arrays to emit light where the maximum value of n is the total number of lasers in each group of laser arrays (sub-laser arrays), for example, in the first mode, control the group of 8 lasers
  • the lasers all emit light, and then the second mode controls that only a few of the laser arrays in each group emit light, such as one, in chronological order, after one group is completed, the next group of operations is performed. Taking Fig.
  • the laser numbers of the second mode are 1-1, 3-1, 4-2, 5-3, 7-4, 9-5, 10-3, 12-1 (refer to Figure 5), wherein the lasers of the second mode are all selected from different groups, thereby further reducing the possibility of optical crosstalk.
  • the 128 lasers are uniformly grouped, of course, they can also be non-uniformly grouped according to the actual situation, that is, the number of lasers in each group of laser arrays can be different.
  • the part of the lasers that emit the second detection laser beam are different from each other, and the second mode is in the s number of the lidar.
  • the horizontal angle is a periodic cycle, where s is an integer greater than or equal to 2. As shown in Fig.
  • the partial laser numbers are 1-1, 3-1, 4-2, 5-3, 7-4, 9-5, 10-3, 12 respectively -1; as shown in Figure 8(b), the part of the laser number at 0.1° is 1-2, 2-7, 3-6, 5-5, 7-2, 10-7, 13-4 respectively , 14-6, where the part of the lasers that emit light in the second mode at 0.0 and 0.1° is not coincident, and the selection method of the second mode laser tries to ensure that the lasers in different positions among the 128 lasers are used in batches as fully as possible , so that the field of view and resolution of short-range detection can be fully guaranteed.
  • each proximity measurement is preferably a single-channel illumination.
  • 8 different proximity channels are selected, so in the cycle of 0.4°, 32 proximity channels are sent and received. Therefore, the distance measurement of the lidar is 128 lines, and the horizontal angular resolution is 0.1°, while the near measurement is 32 lines, and the horizontal angular resolution is 0.4°.
  • Fig. 8 illustrates the luminous sequence arrangement of near and far measuring of the 128-line radar, in which the green block is the time window for distance measuring and the yellow block is the time window for near measuring. Proximity measurement is arranged after the channel completes the distance measurement, and then emits another light to measure the proximity.
  • each proximity measurement is preferably a single-channel luminescence, and in 2 0.1°, 16 different proximity measurement channels are selected, so that in In the cycle of 0.2°, the transceiver of 32 proximity channels is completed. Therefore, the distance measurement of the lidar is 128 lines, and the horizontal angular resolution is 0.1°, while the near measurement is 32 lines, and the horizontal angular resolution is 0.2°.
  • the second mode can not be 32 wires, but a higher or lower wire harness, which can be set according to the actual situation.
  • the high beam lasers in the present invention are not necessarily grouped to emit light in sequence, but can also emit light at the same time.
  • the laser array 101 includes 128 lasers in a first mode, eg, 128 lasers can simultaneously emit a first probe laser beam (with appropriate opto-isolation for providing telemetry data (for telemetry crosstalk effects) is relatively small), and in the second mode, for example, select a plurality of lasers (such as 8, 16, or less than 128 relatively separated in the vertical field of view) to emit a second detection laser beam, such as for proximity measurement (providing measurement Near data).
  • a plurality of lasers such as 8, 16, or less than 128 relatively separated in the vertical field of view
  • the embodiment of the present invention proposes a scheme of independently and alternately performing the distance measurement and the proximity measurement of the lidar.
  • distance measurement all channels (or most of the channels) are turned on to measure mid- and distant targets; in near measurement, only part of the channels are turned on, and the horizontal scanning frequency is reduced, so that only a few channels or even a few channels are illuminated at the same time.
  • Single-channel light emission which can greatly reduce close-range optical crosstalk, or even completely avoid optical crosstalk.
  • the lidar has high beam and high angular resolution when measuring medium and long distances, and low beam and low horizontal angular resolution when measuring short distances.
  • this will not significantly reduce the resolution of close targets, because the detection and identification of close targets requires low wire beam and angular resolution. Too high wire beam and too high horizontal angular resolution There will even be a stack of light spots in the vicinity, creating redundancy.
  • the present invention also relates to a laser radar, as shown in FIG. 9 , which will be described below with reference to the accompanying drawings.
  • the lidar 10 includes the transmitting unit 100 , the receiving unit 120 , and the control unit 130 as described above.
  • the transmitting unit 100 can transmit the first detection laser beam and the second detection laser beam L1/L2 to the outside of the lidar 10 alternately according to the first mode and the second mode, wherein the number of lasers used in the first mode is large.
  • the number of lasers used in the second mode eg for distance and proximity, respectively.
  • the first detection laser beam and the second detection laser beam are diffusely reflected on the target OB, and the radar echoes L1'/L2' return to the lidar and are received by the receiving unit 120.
  • the receiving unit 200 includes a detector array, such as an array of detectors such as APD, SiPM, SPAD, etc.
  • the detector array is configured to receive echoes of the first detection laser beam and the second detection laser beam reflected by the target object. , and convert the echoes into electrical signals.
  • the control unit 130 is coupled to the detector array, and is configured to read the electrical signal output by the detector array, and determine that the electrical signal corresponds to the first detection laser beam or the second detection laser beam, and according to the The electrical signal calculates the distance of the target, and generates point cloud data according to the distance and the judgment result.
  • the receiving unit 120 and the control unit 130 may be configured as separate modules, or may be integrated into an integral module, which are all within the protection scope of the present invention.
  • the control unit 130 may be coupled to the transmitting unit 100, so that the first detection laser beam and the second detection laser beam may be recorded. 2.
  • TOF time-of-flight
  • the distance measurement and the near measurement of the high beam laser radar can be independently alternately performed, and the highest wire beam and angular resolution are used for distance measurement, and the lower wire beam and angular resolution are used for near measurement. , which reduces the number of channels that emit light at the same time during close-up measurement, thereby reducing the optical crosstalk at close range.
  • the present invention also relates to a method 200 for ranging using the lidar 10 as described above, as shown in FIG. 10A and described below with reference to the accompanying drawings.
  • step S201 controlling the laser array to emit a first detection laser beam in a first mode, wherein the first mode includes: controlling n lasers in the laser array to emit light, n is less than or equal to N, and N is the laser The total number of lasers in the array; the first mode is, for example, a telemetry mode, preferably all lasers in the laser array are enabled to sequentially emit the first detection laser beam.
  • the first mode includes: controlling n lasers in the laser array to emit light, n is less than or equal to N, and N is the laser The total number of lasers in the array; the first mode is, for example, a telemetry mode, preferably all lasers in the laser array are enabled to sequentially emit the first detection laser beam.
  • Step S202 controlling some lasers in the laser array to emit a second detection laser beam in a second mode before or after emitting a first detection laser beam in the first mode.
  • the second mode includes controlling the k lasers in the laser array to emit light, wherein the k lasers are selected from the n lasers, and k is less than n; the second mode is, for example, a proximity mode, such as Part of the lasers in the laser array can be activated to emit the second detection laser beams in sequence.
  • the n is equal to the total number N of lasers in the laser array.
  • the second mode is single-channel emission.
  • the n lasers emit light simultaneously, and the k lasers also emit light simultaneously.
  • step S203 Receive echoes of the detection laser beam reflected by the target, convert the echoes into electrical signals, and calculate the distance between the target and the lidar according to the electrical signals.
  • TOF time-of-flight ranging method
  • step S204 it is determined that the electrical signal corresponds to the first detection laser beam or the second detection laser beam.
  • Step S205 Generate point cloud data according to the distance and the judgment result. For example, when it is determined that the electrical signal corresponds to the first detection laser beam (distance measurement mode), if the distance between the target and the laser radar calculated according to the electrical signal is less than the preset distance value (for example, 5 meters), because The electrical signal is used for distance measurement. At this time, you can choose not to use or discard the electrical signal, and not to generate point cloud data. On the contrary, when it is judged that the electrical signal corresponds to the second detection laser beam (proximity mode), if the distance between the target and the laser radar calculated according to the electrical signal is greater than the preset distance value (for example, 5 meters), because The electrical signal is used for proximity measurement. At this time, it is optional to not use or discard the electrical signal, and not to generate point cloud data. Generate more accurate 3D point cloud data using data stitching in distance and proximity modes.
  • the preset distance value for example, 5 meters
  • the step S202 includes: controlling the k lasers in the laser array to emit a second detection laser beam in a second mode after emitting a first detection laser beam in the first mode , as shown in Figures 5 and 6.
  • the step S202 includes: controlling part of the lasers in the laser array to emit a second detection laser beam in a second mode before emitting a first detection laser beam in the first mode, as shown in FIG. 7 . .
  • the first mode includes: at each horizontal angular position of the lidar, controlling the n lasers in the laser array to emit light; the second mode includes: The k lasers in the laser array are controlled to emit light at the same horizontal angular position as the first mode.
  • the laser array is divided into m groups to emit light sequentially, m is an integer and m>1, each group of laser arrays is controlled to emit a first detection laser beam in a first mode, and each group is controlled to emit a first detection laser beam in a first mode.
  • the laser array emits a second probe laser beam in a second mode before or after emitting the first probe laser beam in the first mode.
  • the part of the lasers that emit the second detection laser beam are different from each other, and the second mode is the same as the lidar.
  • the s horizontal angles of are periodic cycles, where s is an integer greater than or equal to 2.
  • the first detection laser beam and the second detection laser beam have different pulse codes, so that the radar echo corresponding to the first detection can be distinguished at the receiving end according to the different pulse codes.
  • the laser beam or the second detection laser beam is used to perform corresponding processing operations.
  • the step S204 includes: judging that the electrical signal corresponds to the first detection laser beam or the second detection laser beam by receiving the time window of the echo.
  • the first detection laser beam and the second detection laser beam may have different pulse codes.
  • both the first detection laser beam and the second detection laser beam can use double pulses, but the double pulses of the two have different time intervals for encoding, so that the receiving end can distinguish the echo corresponding to the echo pulse according to the interval of the echo pulse. Whether it is the first detection laser beam or the second detection laser beam.
  • the first detection laser beam and the second detection laser beam can also be distinguished by the signals read in different time windows reserved by the detectors corresponding to each channel.
  • the first detection laser beam of the mode is used for distance measurement, and the detector (after the laser in this channel emits light in the first mode) reserves a longer first time window for the echo reception of the first detection laser beam reflected from the target. , after the first mode completes the distance measurement, a shorter second time window is reserved for the echo reception of the second detection laser beam of the second mode proximity measurement, so the first time window and the second time window of each channel detector are passed through.
  • the window signal is read to distinguish the first detection laser beam from the second detection laser beam.
  • FIG. 10B shows another method 200' for ranging using the lidar 10 as described above, wherein a first detection laser beam and a second detection laser beam with different pulse codes are used. This is described in detail below with reference to FIG. 10B .
  • Step S201' and step S202' are basically the same as step S201 and step S202 in Fig. 10A, respectively, and will not be repeated here.
  • step S203' according to the pulse code of the echo, it is determined that the echo corresponds to the first detection laser beam or the second detection laser beam. Since the first detection laser beam and the second detection laser beam have different pulse codes, the echoes generated by the first detection laser beam and the second detection laser beam also have corresponding pulse codes, and the echoes can be distinguished according to the pulse codes. Whether the wave corresponds to the first detection laser beam or the second detection laser beam.
  • step S204' according to the judgment result of step S203', according to the time point of emitting the first detection laser beam or the second detection laser beam, the distance of the target object is calculated. If the echo corresponds to the first detection laser beam, use the emission time point of the first detection laser beam to calculate the flight time and the target object distance; otherwise, use the emission time point of the second detection laser beam to calculate the flight time and the target object distance .
  • step S205' point cloud data is generated according to the distance.
  • the present invention proposes a scheme of independently and alternately performing the distance measurement and the proximity measurement of the lidar.
  • distance measurement all channels are turned on to measure targets in the middle and far distances; in near measurement, only part of the channels are turned on, and the horizontal scanning frequency is reduced, so that only a few channels or even a single channel emits light at the same time. It can greatly reduce short-range optical crosstalk, or even completely avoid optical crosstalk.
  • the lidar has high beam and high angular resolution when measuring medium and long distances, and low beam and low horizontal angular resolution when measuring short distances. However, this will not significantly reduce the resolution of close targets, because the detection and identification of close targets requires low wire beams and horizontal angular resolution. Too high wire beams and too high angular resolution There will even be a stack of light spots in the vicinity, creating redundancy.
  • the distance measurement and the proximity measurement of the high-line beam laser radar are independently alternately performed, and the highest wire beam and resolution are used in the distance measurement, and the lower wire beam and resolution are used in the proximity measurement, so that the light beams that emit light at the same time are used for the proximity measurement.
  • the number of channels is reduced, thereby reducing optical crosstalk at close range.
  • the distance measurement and proximity measurement of the high-beam lidar are independently alternated.
  • the highest wire beam and resolution are used for distance measurement, and the lower wire beam and resolution are used for near measurement, so that the lights that emit light at the same time are used for near measurement.
  • the number of channels is reduced.
  • the lidar can use more channels to emit light in parallel to improve the resolution of distant targets; at the same time, fewer channels are used to measure near targets, and the simultaneous emission channels are as few as possible when measuring near. The interference between the simultaneous light-emitting channels is reduced, so that the accuracy of the near measurement is greatly improved.
  • the second aspect of the present invention is based on the first aspect, according to the results of the laser radar short-range detection, to feedback control the distance measuring light intensity when the laser radar scans to the same position or a nearby position next time, which can be greatly reduced
  • the luminous intensity of the laser in the distance measurement mode is even turned off to reduce the power consumption of the lidar. Details are described below.
  • the luminous effect of those lasers in the distance measurement mode is smaller than that of the laser in the proximity mode, so the luminous intensity of the distance measurement mode is reduced without changing the
  • the luminous intensity of the proximity mode can reduce the overall power consumption of the lidar without affecting the short-range detection capability.
  • the luminous intensity of the laser in the distance-measuring mode is greatly reduced or even turned off. In the case of , reduce the power consumption of lidar.
  • FIG. 11 shows a control method 300 of a lidar according to an embodiment of the present invention.
  • the control method 300 can be implemented by the lidar described in the first aspect of the present invention. More specifically, the lidar implementing the control method 300 includes a laser array having N lasers.
  • the control method 300 includes the following steps.
  • step S301 control n lasers to emit a first detection laser beam, and control k lasers to emit a second detection laser beam; wherein n ⁇ N, the k lasers are selected from the n lasers, k ⁇ n.
  • the first detection laser beam may be emitted before the second detection laser beam, or may be emitted later than the second detection laser beam. If the first detection laser beam is used for distance measurement, the light intensity of the first detection laser beam may be greater than that of the second detection laser beam.
  • the lidar performs angular triggering at 0°, 0.2°, 0.4°... and performs a period of detection (detection period) at each angle.
  • the lidar performs luminescence detection as shown in Figure 5.
  • multiple lasers of the lidar emit light. The lasers all emit light at this angle (although there is actually a certain angular displacement).
  • the first detection laser beams emitted by the n lasers are usually high in intensity, so they are used in the telemetry mode (the first mode), and the second detection laser beams emitted by the k lasers have a lower intensity and are usually used for measurement.
  • Near Mode (Second Mode)
  • the transmitting unit including 128 lasers 8 lasers are selected, and their numbers are 1-1, 3-1, 4-2, 5-3, 7-4, 9-5, 10- 3. 12-1, after the normal long-range mode launch, each of these 8 lasers additionally has a near-mode launch. Therefore, 8 times of near emission are inserted in the 128 channels of luminous remote measurement in turn.
  • the emission of the first detection laser beam is located after the emission of the second detection laser beam.
  • the present invention is not limited to this, and the emission of the first detection laser beam can also be located in the second detection laser beam. Before the emission of the laser beam, as shown in Figure 7.
  • Step S302 Receive echoes reflected by the first detection laser beam and the second detection laser beam on the target.
  • part of the reflected beam returns to the lidar, which is received by the detector of the lidar's receiving unit and converted into an electrical signal.
  • step S303 Calculate the distance of the target object according to the echo.
  • the distance to the target can be calculated.
  • the first detection laser beam and the second detection laser beam may have different pulse codes.
  • both the first detection laser beam and the second detection laser beam can use double pulses, but the double pulses of the two have different time intervals for encoding, so that the receiving end can distinguish the echo corresponding to the echo pulse according to the interval of the echo pulse.
  • the distance of the target object is calculated according to the time point when the first detection laser beam or the second detection laser beam is emitted.
  • both the first detection laser beam and the second detection laser beam are double pulses
  • the time interval between the first pulse p1 and the second pulse p2 of the first detection laser beam is ⁇ t1
  • the first pulse p1 of the second detection laser beam The time interval between the second pulse p2 and the second pulse p2 is ⁇ t2. If two pulses with an interval of ⁇ t1 are received, it can be judged as corresponding to the first detection laser beam; similarly, if two pulses with an interval of ⁇ t2 are received, The pulse can be determined to correspond to the second detection laser beam.
  • the first detection laser beam and the second detection laser beam are both three pulses
  • the time interval between the first pulse p1 and the second pulse p2 of the first detection laser beam is ⁇ t1
  • the first detection laser beam The time interval between the second pulse p2 and the third pulse p3 is ⁇ t1
  • the time interval between the first pulse p1 and the second pulse p2 of the second detection laser beam is ⁇ t2
  • the second pulse p2 of the second detection laser beam The time interval between the third pulse p3 and the third pulse p3 is ⁇ t2".
  • the intervals are ⁇ t1 and ⁇ t1" in turn, it can be judged as corresponding to the first detection laser beam; similarly, if three pulses are received before and after the , and the intervals are ⁇ t2 and ⁇ t2” in sequence, which can be determined to correspond to the second detection laser beam.
  • the first detection laser beam and the second detection laser beam can also be distinguished by the signals read in different time windows reserved by the detectors corresponding to each channel.
  • the detector can reserve a longer first time window (after the first detection laser beam is emitted from the channel laser) for receiving the echo reflected by the first detection laser beam from the target, and then reserve a longer time window.
  • the short second time window is used for the echo reception of the second detection laser beam, so through the first time window and the second time window of each channel detector, it can be determined that the echo corresponds to the first detection laser beam or the second detection laser beam .
  • the time-of-flight TOF is obtained, multiplied by the speed of light c and divided by 2 to obtain the distance between the target and the lidar.
  • distance measurement and proximity measurement can be decomposed by 3 meters.
  • the distance between the target object and the lidar is greater than 3 meters, it belongs to distance measurement, which corresponds to the TOF time of more than 20ns.
  • it is less than 3 meters it belongs to the near measurement, corresponding to the TOF time within 20nm.
  • the receiving end starts to receive echo signals, but the signals within TOF ⁇ 20ns are directly filtered out. , and no further processing is performed; in the proximity mode: use part of the lasers in the laser array 101 to emit light alternately for detection, correspondingly, the receiving end starts to receive the echo signal, but only receives the signal within the duration of TOF ⁇ 20ns, According to further processing of these signals, the actual distance and reflectivity of possible objects within a range of 3m from the lidar are detected.
  • the possible distance between the target and the lidar can also be calculated according to the detected echoes and the time points at which the first detection laser beam and the second detection laser beam are emitted. Then it is judged that the echo signal corresponds to the first detection beam or the second detection beam (for example, the expected detection distance corresponding to each detection beam is determined), and the distance of the target object is determined from two possible distances.
  • Step S304 when a target is detected within a preset distance, in the next detection period, in a range corresponding to the target, at least some of the n lasers emit light of the first detection laser beam to be reduced light intensity.
  • the lidar rotates to the angular range corresponding to the target, the light emitted in the distance measurement mode can be reduced. At least some of the n lasers emit the luminous intensity of the first detection laser beam, thereby saving power consumption and reducing crosstalk.
  • the range of the preset distance can be determined according to the usage scenario and technical parameters of the lidar. For example, within 5 meters from the lidar, it can be considered as within the preset distance, and beyond 5 meters as outside the preset distance.
  • the present invention it is also possible to predict the approximate corresponding angular range when the same object is scanned next time according to the type and motion parameters of the target and the detection parameters of the lidar, and reduce the first angular range within the predicted angular range. Detects the luminous intensity of the laser beam. For example, the angular range of the next time the lidar scans the object can be predicted based on the type of the object (dynamic or static), the speed of motion, the direction, the rotational speed of the lidar, or the angular velocity of the galvanometer/swing mirror inside the lidar, etc. , reducing the luminous intensity of the first detection laser beam.
  • the first detection laser beam of the telemetry mode and the second detection laser beam of the proximity mode can be independently separated.
  • the luminous intensity of the first detection laser beam is adjusted accordingly (if there is an object at close range, the light intensity of the first detection laser beam is reduced; if there is no object, the light intensity of the first detection laser beam is kept unchanged) , and the luminous intensity of the second detection laser beam may not be adjusted at the same time. In this way, the luminous power consumption of distance measurement can be reduced without reducing the short-range detection capability.
  • Fig. 12a shows the detection strategy of the lidar according to the second aspect of the present invention.
  • Figure 12a shows a top view of the lidar, where the lidar is rotated in the direction of the arrow on the page.
  • the lines in Figure 12a represent the detection laser beams emitted by the lidar as it rotates to different positions (angles).
  • the thick solid line represents the first detection laser beam with higher luminous intensity (strong)
  • the thin solid line represents the first detection laser beam with lower luminous intensity (weak)
  • the dashed line represents the second detection laser beam.
  • the lidar during the first detection, the lidar emits the first detection laser beam with a normal high-intensity luminous intensity, and for some of the lasers, the first detection laser beam is increased before or after the emission of the first detection laser beam.
  • the second detects the emission of the laser beam and, based on the echoes, determines that there is an object at a position closer to the lidar.
  • the lidar when the lidar rotates to the position corresponding to the target next time, the lidar can reduce the light intensity of the first detection laser beam emitted by the laser. In this way, the power consumption of the lidar can be reduced.
  • the luminous intensity of the second detection laser beam in the near-detection mode is not affected, and it can still ensure that nearby objects can be detected. Therefore, as shown in Figure 12b, it can still ensure that the echoes generated by the reflection of nearby objects are higher than the threshold value. Th.
  • the angle range ⁇ of the target within the preset distance is obtained (as shown in FIG. 12b ), and the angle range ⁇ of the n lasers at the angle is reduced
  • the laser within the range ⁇ emits the luminous intensity of the first detection laser beam in the next detection period.
  • the lidar can roughly determine the angular range ⁇ of the target according to the point cloud. For example, at the edge position of the angle range ⁇ (as shown in Fig.
  • the distance corresponding to the point cloud changes abruptly, that is, the distance of the point within the angle range is smaller, and the distance at this angle Outside the range, the distance of the points increases suddenly.
  • the angular range of nearby objects can be roughly outlined.
  • part of the n lasers within the angle range ⁇ may be turned off in the next detection period.
  • FIG. 12b only shows the angular range ⁇ of the target in the horizontal direction, and the angular range of the target in the vertical direction can also be obtained, which will not be repeated here.
  • the intensity of the first detection laser beam is reduced.
  • the light intensity of the radar's near detection is not reduced, so whether it is the first detection or the second detection, close objects can be detected.
  • the normal luminous intensity of the first detection laser beam in the distance-measuring mode is the luminous light of the second detection laser beam in the proximity-measuring mode
  • the luminous intensity of the second detection laser beam is lower than the human eye safety threshold, and the luminous intensity of the second detection laser beam is higher than that of the reduced first detection laser
  • the light intensity of the beam is measured in the right picture in Figure 12a).
  • the second detection laser beam emitted by the laser will detect the object.
  • Figure 13a it shows that the first detection laser beam and the second detection laser beam emitted in the first detection detect objects at a short distance, wherein the size of the light spot is to characterize the relative size of the laser light intensity , which may or may not match the actual size of the emitted light spot.
  • the detected point cloud can continue to refer to Figure 12b above. It can be seen that the lateral (horizontal) and longitudinal (vertical) resolutions generated by the second detection laser beam are likely to be lower than those generated by the first detection laser beam, as shown in Figure 13a. It can be seen from the scanning spot diagram on the right in , the longitudinal resolution generated by the second detection laser beam is about half (2/4) of the longitudinal resolution generated by the first detection laser beam.
  • the angular range (horizontal angle and vertical angle) of the nearby object can be calculated, and then the luminous intensity of all channels within this angular range is reduced when the first detection laser beam is emitted, as shown in Figure 13b , when the position corresponding to the near target is scanned for the second time, the luminous intensity of the first detection laser beam is reduced, but since the luminous intensity of the second detection laser beam does not change, because the second detection obtains
  • the point cloud image of can still be as shown in Figure 12b above, so it can ensure that the lidar can reduce the power consumption without losing the short-range detection ability.
  • step S304 it is preferable to use the calculation of the influence domain of each near point cloud to outline the angular range of the near object.
  • the so-called area of influence may be the range of the point cloud (or wire bundle) affected by the short-range detection result of each near-measured point cloud.
  • one (or more) lasers and a detector form a detection channel.
  • a detection channel detects a short-range object at a certain horizontal angle in the proximity mode, and then the detection channel will detect this object.
  • the information is transmitted to the detection channels around it, and the information that "there is an object at a close distance at the current position" is conveyed to the surrounding detection channels.
  • the high beam intensity is reduced.
  • the division of the influence domain can be divided by the midline between the two near point clouds, so that the position of each far point cloud can be notified.
  • the strategy of reducing the luminous intensity of the distance measurement mode can be adopted in advance and cancelled after a delay.
  • the light intensity for distance measurement can be reduced in advance, and when it has left the angular range of the close-range object, a relatively low light intensity for distance measurement can be maintained.
  • the range of advance and delay can be set by preset.
  • FIG. 14 shows a method 400 of operation of a lidar.
  • step S401 the lidar performs the first detection, and respectively emits detection laser beams in the distance-measuring mode and the proximity-measuring mode.
  • step S402 it is determined whether there is a close-range object. If there is a close-range object, proceed to step S403; otherwise, proceed to step S405.
  • the range of the short distance can be determined according to the usage scenario and technical parameters of the lidar. For example, within 5 meters from the lidar, it can be considered as a short distance, and beyond 5 meters is not a short distance.
  • step S403 the angular range of the near object is calculated, for example, the angular range in the horizontal direction and the angular range in the vertical direction.
  • step S404 a second detection is performed, that is, when the lidar rotates to the angular range of the near object next time, the luminous intensity of the distance measuring mode is reduced, and the detection laser beam is emitted in the distance measuring mode + the near measuring mode.
  • step S405 if there is no short-range object, when the lidar rotates to the same angle range next time, it is not necessary to change the luminous intensity of the distance-measuring mode, and the detection laser beam is still emitted in the combination of the distance-measuring mode and the proximity-measuring mode.
  • step S403 it is preferable to calculate the influence domain of each near point cloud to outline the angular range of the near object.
  • the so-called area of influence may be the range of the point cloud (or wire bundle) affected by the short-range detection result of each near-measured point cloud.
  • a laser and a detector form a detection channel.
  • a detection channel detects an object at a short distance at a certain horizontal angle in the proximity mode, and then the detection channel will transmit this information to its surroundings.
  • the detection channel conveys the information of "there is an object at a close distance at the current position" to the surrounding detection channels, and then after these surrounding detection channels receive this information, the distance measurement light intensity will be reduced within this angle range.
  • the division of the influence domain can be divided by the midline between the two near point clouds, so that the position of each far point cloud can be notified.
  • the strategy of reducing the luminous intensity of the distance measurement mode can be adopted in advance and cancelled after a delay.
  • the light intensity for distance measurement can be reduced in advance, and when it has left the angular range of the close-range object, a relatively low light intensity for distance measurement can be maintained.
  • the range of advance and delay can be set by preset.
  • the second aspect of the present invention also relates to a laser radar, the structure of which is shown in FIG.
  • the laser array 101 is configured to emit a detection laser beam.
  • the receiving unit 120 includes a detector array, which can receive the echoes reflected by the detection laser beam on the target and convert them into electrical signals.
  • the control unit is coupled to the laser array and the receiving unit, and is configured to calculate the distance of the target object according to the electrical signal, and can control the n lasers to emit a first detection laser beam, and control the k lasers to emit a second laser beam detection laser beam; wherein n ⁇ N, the k lasers are selected from the n lasers, k ⁇ n, the light intensity of the first detection laser beam is greater than the light intensity of the second detection laser beam; wherein the The control unit is configured to: when a target object is detected within a preset distance, in the next detection period, within a range corresponding to the target object, reduce the rate at which at least some of the n lasers emit the first detection laser beam. Luminous light intensity.
  • the control unit 130 may perform the control method of the lidar as described above. For example, the control unit may obtain the angular range of the target object within the preset distance according to the distance of the target object output by the control unit, and reduce the number of lasers within the angular range among the n lasers in the next The luminous intensity of the first detection laser beam emitted in the detection period. The control unit may obtain the angular range of the target within the preset distance according to the distance of the target output by the control unit, and turn off the n lasers within the angular range in the next detection cycle. The emission of the first detection laser beam of the partial laser.
  • p lasers and one detector form a detection channel, p ⁇ 1
  • the control unit is configured to: when one of the detection channels detects a target within a preset distance, control the The laser of the detection channel within a preset range around the detection channel reduces the luminous intensity of the first detection laser beam emitted in the next detection period.
  • the preset range is divided according to a midline between two near-point clouds.
  • control unit is configured to: obtain the angular range of the target within the preset distance according to the distance of the target output by the control unit, and reduce the angular range of the target
  • the lasers within and within the preset range adjacent to the angular range emit the luminous intensity of the first detection laser beam in the next detection period.
  • control unit is configured to: modify the detection rate in the next detection period according to one or more of the type of the target, motion parameters, and detection parameters of the lidar angular range.
  • the first detection laser beam is used to measure a target at a longer distance
  • the N lasers are divided into m groups to emit light sequentially, m is an integer and m>1
  • the control unit is configured to: at each horizontal angular position of the lidar, control n lasers in each group of laser arrays to emit a first detection laser beam; At the horizontal angular position, the k lasers in the laser array are controlled to emit a second probe laser beam before or after the first probe laser beam is emitted.
  • the first detection laser beam and the second detection laser beam have different pulse codes
  • the control unit is configured to: determine that the echo corresponds to the first detection laser beam or the second detection laser beam according to different pulse codes, and according to the time when the first detection laser beam or the second detection laser beam is emitted point to calculate the distance to the target.
  • control unit is configured to: determine that the echo corresponds to the first detection laser beam or the second detection laser beam by receiving the time window of the echo, and to transmit the echo according to the first detection laser beam or the second detection laser beam. At a time point of the detection laser beam or the second detection laser beam, the distance of the target object is calculated.
  • control unit is configured to: according to the detected echoes and the time points at which the first detection laser beam and the second detection laser beam are emitted, respectively calculate and obtain the possibility between the target object and the lidar distance; determine that the echo signal corresponds to the first detection laser beam or the second detection laser beam, and determine the distance of the target object.
  • the present invention also relates to a computer-readable storage medium comprising computer-executable instructions stored thereon which, when executed by a processor, implement the control method as described above.
  • the laser light intensity of the distance-measurement can be greatly reduced or even turned off. Radar power consumption.

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Abstract

一种激光雷达的控制方法，其中激光雷达包括具有N个激光器的激光器阵列（101），控制方法包括：控制n个激光器发出第一探测激光束（L1），且控制其中k个激光器发出第二探测激光束（L2）；其中n≤N，k个激光器选自n个激光器，k＜n，第一探测激光束（L1）的光强大于第二探测激光束（L2）的光强（S301）；接收第一探测激光束（L1）和第二探测激光束（L2）在目标物上反射的回波（S302）；根据回波，计算目标物的距离（S303）；当在预设距离内探测到目标物时，在下一探测周期中在与目标物对应的范围内降低n个激光器中的至少部分激光器发射第一探测激光束（L1）的发光光强（S304）。

Description

激光雷达的控制方法及激光雷达 技术领域
本公开涉及光电探测技术领域，尤其涉及一种在不减弱近距离探测能力的基础上降低激光雷达发光光强的控制方法及激光雷达。
背景技术
激光雷达LiDAR是激光主动探测传感器设备的一种统称，其工作原理大致如下：激光雷达的发射器发射出一束激光，激光光束遇到物体后，经过漫反射，返回至激光接收器，雷达模块根据发送和接收信号的时间间隔乘以光速，再除以2，即可计算出发射器与物体的距离。根据激光线束的多少，通常有例如单线激光雷达、4线激光雷达、8/16/32/64线激光雷达等。线束越高，激光雷达的结构越复杂，集成度越高。对于高集成度的激光雷达，需要尽可能减少电功耗。
在很多实际安装使用的过程中，距离激光雷达很近的地方可能存在一些有意设置的遮挡物，比如某些线束在某些水平角度下被车体遮挡；另外例如只用到激光雷达的部分水平角度的探测范围，其它角度被遮挡。同时，在激光雷达的使用环境中，也经常在距离雷达很近(比如≤3m)的地方出现一些目标物。对这些近距离目标物的探测无需过高的探测光强就可以实现，从而可以节约功耗。在一些激光雷达的方案中，根据激光雷达的探测结果，如果探测到近处存在物体，则在下一次扫描到同样的角度范围时降低发光光强，仅仅满足近处测量的光强需求，从而降低功耗。但这种策略虽然降低了发光光强，但可能产生近处物体探测不到的情况。
参考图1A所示，第一次探测时发射光强很高，并且探测到近处有物体；参考图1B所示，第二次扫描到近处物体的角度范围时，降低发光光强，但可能近处物体反射后的回波强度达不到阈值Th，使得该近处物体在在第二次扫描时无法被探测到。因此虽然降低了功耗，但减弱甚至丧失了近距离探测的能力。
图1C解释了收发非同轴的激光雷达在降低功耗的同时减弱甚至丧失了近距离探测能力的原因。在激光雷达设定测远处视场匹配的一个激光器和一个探测器即构成一个通道，如图1C所示，对于激光雷达的通道A和通道B，当激光雷达用于探测远处的物体时，通道A的激光器发出的探测激光束L0被远处目标物OB1反射后，雷达回波接近于平行光，会照射到通道A的探测器上D1，如图1C中左上方所示的，这是比较理想的情况，。而当激光雷达用于探测近处OB2的物体时，通道A的激光器发出的探测激光束L0被近处目标物反射后，雷达回波不能近似为平行光，在到达探测器所在的焦平面时发生光斑偏移和弥散，会照射到通道A探测器旁边的通道B探测器上D2，如图1C中左 下方所示的，这种光斑的偏移和弥散会造成激光雷达通道间的光串扰，光斑的偏移和弥散随距离越近越明显，因此对于近距目标物探测使用的线数越多，越影响激光雷达的测距精度和准确性。
为了避免同一雷达在测量远近物体时由于光斑的偏移和弥散导致测距不准的现象，传统方法采用了测远、测近组合式雷达的解决方案，其中一台雷达专门测量远处的物体，另一台雷达专门测量近处的物体，这样虽然可以改善近距测量性能，但增加了系统成本，安装和调试的困难。
背景技术部分的内容仅仅是公开人所知晓的技术，并不当然代表本领域的现有技术。
发明内容
本发明提供一种在不减弱近距离探测能力的基础上，降低激光雷达发光光强的控制方法及激光雷达。
本发明提供一种激光雷达的控制方法，其中所述激光雷达包括具有N个激光器的激光器阵列，所述控制方法包括：
S301：控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n，所述第一探测激光束的光强大于所述第二探测激光束的光强；
S302：接收所述第一探测激光束和第二探测激光束在目标物上反射的回波；
S303：根据所述回波，计算所述目标物的距离；和
S304：当在预设距离内探测到目标物时，在下一探测周期中在与所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
根据本发明的一个方面，所述步骤S304包括：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低所述n个激光器中处于所述角度范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个方面，所述步骤S304包括：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并在下一探测周期中关闭所述n个激光器中处于所述角度范围内的部分激光器。
根据本发明的一个方面，p个激光器与一个探测器构成一个探测通道，p≥1，所述步骤S304包括：当其中一个探测通道探测到处于预设距离内的目标物时，控制所述探测通道周围预设范围内的探测通道的激光器，降低在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个方面，所述预设范围根据两个测近点云之间的中线进行划分。
根据本发明的一个方面，所述步骤S304包括：根据所述目标物的类型、 运动参数、激光雷达的探测参数中的一个或多个，修正所述下一探测周期中的所述角度范围。
根据本发明的一个方面，相比于所述第二探测激光束，所述第一探测激光束用以测量于更远距离的目标物，所述N个激光器分为m组依序发光，m为整数且m>1，所述步骤S301包括：
在所述激光雷达的每个水平角位置处，控制每组激光器阵列中的n个激光器发出第一探测激光束；
在相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器，在发出第一探测激光束之前或之后发出第二探测激光束。
根据本发明的一个方面，所述第一探测激光束和第二探测激光束具有不同的脉冲编码；
所述步骤S303包括:根据不同的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个方面，所述步骤S303包括：
通过接收所述回波的时间窗口，判断所述回波对应于第一探测激光束或第二探测激光束，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个方面，所述步骤S303包括：
根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离；
判断所述回波信号对应于第一探测激光束或第二探测激光束，确定所述目标物的距离。
本发明还提供一种激光雷达，包括：
具有N个激光器的激光器阵列，配置成可发射出探测激光束；
接收单元，包括探测器阵列，可接收所述探测激光束在目标物上反射的回波并转换为电信号；和
控制单元，耦接到激光器阵列和接收单元，配置成可根据所述电信号，计算所述目标物的距离，并且可控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n，所述第一探测激光束的光强大于所述第二探测激光束的光强；其中所述控制单元配置成：当在预设距离内探测到目标物时，在下一探测周期中于所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
根据本发明的一个方面，所述控制单元配置成：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低所述n个激光器中处于所述角度范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个方面，所述控制单元配置成：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并在下一探测周期中关闭所述n个激光器中处于所述角度范围内的部分激光器的发射第一探测激光束的发射。
根据本发明的一个方面，p个激光器与一个探测器构成一个探测通道，p≥1，所述控制单元配置成：当其中一个探测通道探测到处于预设距离内的目标物时，控制所述探测通道周围预设范围内的探测通道的激光器，降低在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个方面，所述预设范围根据两个测近点云之间的中线进行划分。
根据本发明的一个方面，所述控制单元配置成：根据所述控制单元输出的目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低处于所述角度范围内以及邻近所述角度范围的预设范围内的激光器在下一探测周期中测远模式的发光光强。
根据本发明的一个方面，所述控制单元配置成：根据所述目标物的类型、运动参数、激光雷达的探测参数中的一个或多个，修正所述下一探测周期中的所述角度范围。
根据本发明的一个方面，相比于所述第二探测激光束，所述第一探测激光束用以测量于更远距离的目标物，所述N个激光器分为m组依序发光，m为整数且m>1，所述控制单元配置成：在所述激光雷达的每个水平角位置处，控制每组激光器阵列中的n个激光器发出第一探测激光束；在相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器，在发出第一探测激光束之前或之后发出第二探测激光束。
根据本发明的一个方面，所述第一探测激光束和第二探测激光束具有不同的脉冲编码；
所述控制单元配置成:根据不同的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个方面，所述控制单元配置成：通过接收所述回波的时间窗口，判断所述回波对应于第一探测激光束或第二探测激光束，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个方面，所述控制单元配置成：根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离；判断所述回波信号对应于第一探测激光束或第二探测激光束，确定所述目标物的距离。
本发明还提供一种计算机可读存储介质,包括存储于其上的计算机可执行指令，所述可执行指令在被处理器执行时实施如上所述的控制方法。
附图说明
构成本公开的一部分的附图用来提供对本公开的进一步理解，本公开的示意性实施例及其说明用于解释本公开，并不构成对本公开的不当限定。在附图中：
图1A及图1B示出了激光雷达所采用的近处有物体时就降低发光光强的策略的示意图；
图1C解释了降低功耗的同时减弱甚至丧失了近距离探测能力的原因；
图2示出了根据本发明一个实施例的激光雷达的发射单元的示意图；
图3示出了根据本发明一个实施例的激光器阵列的示意图；
图4A示出了激光雷达在远处目标物上各个激光束扫过的轨迹；
图4B示出了激光雷达在近处目标物上光斑存在堆叠和冗余的示意图；
图5示出了根据本发明一个实施例的激光器阵列的多个激光器的逻辑排布(发光时序)；
图6示出了根据本发明一个实施例的第一模式和第二模式的发光时序；
图7示出了根据本发明另一个实施例的第一模式和第二模式的发光时序；
图8示出了根据本发明一个实施例在相邻水平角位置处的激光器阵列的逻辑排布(发光时序)；
图9示出了根据本发明一个实施例的激光雷达的示意图；
图10A示出了根据本发明一个实施例的利用激光雷达进行测距的方法的示意图；
图10B示出了根据本发明另一个实施例的利用激光雷达进行测距的方法的示意图；
图11示出了根据本发明一个实施例的激光雷达的控制方法的流程图；
图12a示出了本发明第二方面的激光雷达的发光强度的示意图；
图12b示出了采用图12a的方案的激光雷达点云的示意图；
图13a和13b示出了根据本发明一个实施例的激光雷达第一次探测和第二次探测的示意图；
图14示出了根据本发明一个实施例的激光雷达的工作方法；
图15示出了根据本发明一个实施例的影响域的划分示意图；
图16示出了根据本发明一个实施例降低水平角度分辨率的探测示意图；和
图17示出了根据本发明一个实施例降低垂直角度分辨率的探测示意图。
具体实施方式
在下文中，仅简单地描述了某些示例性实施例。正如本领域技术人员可认识到的那样，在不脱离本发明的精神或范围的情况下，可通过各种不同方式修改所描述的实施例。因此，附图和描述被认为本质上是示例性的而非限制性的。
在本发明的描述中，需要理解的是，术语"中心"、"纵向"、"横向"、"长度"、"宽度"、"厚度"、"上"、"下"、"前"、"后"、"左"、"右"、"竖直"、"水平"、"顶"、"底"、"内"、"外"、"顺时针"、"逆时针"等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。此外，术语"第一"、"第二"仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有"第一"、"第二"的特征可以明示或者隐含地包括一个或者更多个所述特征。在本发明的描述中，"多个"的含义是两个或两个以上，除非另有明确具体的限定。
在本发明的描述中，需要说明的是，除非另有明确的规定和限定，术语"安装"、"相连"、"连接"应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接:可以是机械连接，也可以是电连接或可以相互通讯；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通或两个元件的相互作用关系。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之"上"或之"下"可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征"之上"、"上方"和"上面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征"之下"、"下方"和"下面"包括第一特征在第二特征正上方和斜上方，或仅仅表示第一特征水平高度小于第二特征。
下文的公开提供了许多不同的实施方式或例子用来实现本发明的不同结构。为了简化本发明的公开，下文中对特定例子的部件和设置进行描述。当然，它们仅仅为示例，并且目的不在于限制本发明。此外，本发明可以在不同例子中重复参考数字和/或参考字母，这种重复是为了简化和清楚的目的，其本身不指示所讨论各种实施方式和/或设置之间的关系。此外，本发明提供了的各种特定的工艺和材料的例子，但是本领域普通技术人员可以意识到其他工艺的应用和/或其他材料的使用。
以下结合附图对本发明的优选实施例进行说明，应当理解，此处所描述的优选实施例仅用于说明和解释本发明，并不用于限定本发明。
第一方面
本发明的第一方面涉及一种激光的发射单元，例如可用作激光雷达的发射单元，下面参考附图详细描述。
如图2所示，发射单元100包括：激光器阵列101和控制单元102。其中激光器阵列101包括多个激光器，设置在一个或多个基板上，每个激光器可 以单独被驱动控制发光。图2中示意性示出了激光器阵列101包括的多个激光器设置在一个基板(例如电路板)，的示意图，激光器阵列101例如包括四列激光器，共计30个激光器。本领域技术人员容易理解，本发明不限于此，激光器阵列101可包括更多或更少数目的激光器，并且激光器的物理排布方式可以根据需要任意设定，例如也可以构思将多个激光器设置在多个基板上，如图3所示。根据本发明的一个实施例，所述发射单元100还包括发射透镜(未示出)，用于将激光器出射的每束激光束调制(准直)成平行光并出射到激光雷达周围的环境空间中，激光器阵列101中每个激光器优选位于发射透镜焦平面上的不同高度处，经发射透镜出射后对应不同的垂直视场。
图3示出了根据本发明另一个实施例的激光器阵列101。其中激光器阵列101包括多个基板1012以及布置在各个基板1012上的激光器1011，其中每个激光器1011在发射透镜焦平面的不同的高度处，分别对应于激光雷达的不同的垂直视场。
如图2所示，控制单元102与所述激光器阵列101耦接，并配置成可控制所述激光器阵列101中的激光器进行发光。控制单元102可包括高压单元和逻辑控制单元，其中高压单元用于产生驱动所述激光器发光需要的高压，逻辑控制单元用于控制所述激光器阵列101的发光时序和逻辑。下面详细描述。
在一个示例中，本发明的激光雷达为角度触发，在激光雷达的每个水平角位置处，激光雷达完成一次完整的测距过程。例如，激光雷达水平角分辨率为0.2°，激光雷达的每个水平角即每0.2°，从0°开始，在0°、0.2°、0.4°…进行角度触发完成一次完整的测距过程。以转速10Hz,水平角分辨率0.2°，200m测远为例，一次测远飞行时间为1.34us，转过0.2°耗时55.6us，也就是说在这个时间内最多允许收发41次光(55.6/1.34＝41.5)，对于中高线数激光雷达，例如64、128线要满足高水平角分辨率，长距离的测远要求，就需要多通道同时发光。而且，水平角分辨率越高，测远要求越远，则同时发光通道的数量就越多。本发明的发明人发现：高线束激光雷达，通道排列密集，同时发光的通道数越多越容易产生光串扰。这种串扰对于探测较远处的目标物的影响尚可接受，但是当测量近处的目标物时，通道间的相互干扰非常严重。从点云上看就是近距离时目标物测距不准且通道一致性差。
如图4A和4B所示，高线束激光雷达在探测近处目标物时所有通道都发光测距的话竖直和水平角分辨率都是过剩的。如图4A所示，由于激光雷达不同线是放射发散的，当探测远处的目标物时，由于距离较远，所以在目标物上扫描的激光光斑能够清楚的间隔开。由于距离远，反射回雷达的激光，基本是平行光，光斑在焦面的位置受距离影响小，所以对远距离物体的扫描，此时能够最大化地利用激光雷达的全部通道和最大性能。而当探测近处的目标物时，激光束放射发散的距离短，因此在目标物上各个激光束扫过的轨迹密集，所以存在严重的光斑堆叠和冗余，同时考虑近距光斑的漂移和弥散， 即浪费了激光束又会对于激光雷达的测量精度造成影响。
因此，根据本发明的实施例，所述控制单元102配置成可以在第一模式下采用较多的激光器发光，提高对远处目标物的分辨率；同时，在第二模式下，采用较少通道来测量近处目标物，并且测近时同时发光通道尽可能少，优选的为单通道，以减少同时发光通道之间的干扰，使得近处测量的精度大大提高。具体的，所述第一模式包括：控制所述激光器阵列101中的n个激光器发光，n小于等于N，N为所述激光器阵列中激光器的总数；所述第二模式包括，控制所述激光器阵列中的k个激光器发光，其中所述k个激光器选自所述n个激光器，k小于n。优选的所述n等于所述激光器阵列中激光器的总数N，优选地第二模式为单通道发光,优选地所述n个激光器同时发光，所述k个激光器也同时发光。在本发明的一个实施例中，例如激光器阵列101中的激光器总数是8个(N＝8)，在第一模式控制所述激光器阵列101中的8个激光器发光，优选地所述8个激光器同时发光，在第二模式控制所述激光器阵列101中的2个激光器发光，优选地所述2个激光器同时发光，或者优选地在第二模式控制所述激光器阵列101中的1个激光器单通道发光，更进一步地减小通道串扰。
在本发明的一个实施例中，其中所述第一模式包括：在所述激光雷达的每个水平角位置处，控制所述激光器阵列中的所述n个激光器发光；所述第二模式包括：在与所述第一模式相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器发光。例如上文中所述的激光雷达的水平角分辨率为0.2°，激光雷达的每个水平角即每0.2°，从0°开始，在0°、0.2°、0.4°…进行角度触发。即在每个角度0°、0.2°、0.4°…激光器阵列101执行第一模式和第二模式的发光测距，当然激光雷达的水平角分辨率也可以为0.1°或其它角度，根据探测需要进行设定。
上文中仅是激光器阵列101中包括8个激光器为示例简单说明第一模式和第二模式，高线束激光雷达通常可以达到40、64、128以及更高线数，由于受探测距离和水平角分辨率的制约，高线束激光雷达通常需要分多组按序进行发光，每组激光器阵列即子激光器阵列。
根据本发明的一个优选实施例，所述激光器阵列分为m组依序发光，m为整数且m>1，所述控制单元配置成可控制每组激光器阵列以第一模式发出第一探测激光束，并配置成可控制所述每组激光器阵列在以所述第一模式发出第一探测激光束之前或之后以第二模式发出第二探测激光束。在激光雷达的每个水平角位置处，所述m个子激光器阵列均按模式完成发光。优选地，这m个子阵第一模式和第二模式的先后顺序是一致的。例如对于这m子激光器阵列均先进行第一模式再进行第二模式。m组依序发光是指按时间顺序，一组完成后再进行下一组操作。优选地每个子激光器阵列中，每一模式发光的激光器可以是同时发光，第二模式发光的激光器可以是同时发光。根据本发明的一个实施例，如分组数m较多时，部分子激光器阵列第二模式发光的激光器 可以等于0。
以下参考附图详细描述。
图5示出了激光器阵列101的多个激光器的逻辑排布(发光时序)，其中以激光器阵列101包括128个激光器为例进行说明。通常对于高线束的激光雷达，在控制发光时序时，需要将多个激光器并行发光。如图3所示，可以将128个激光器分为16组，每组8个激光器同时发光，一共发16次，可完成128个激光器的发射。图5中水平方向为发光时刻的顺序，将激光器分为16组，每组8个激光器。为方便起见，在第一时刻发光的8个激光器的编号为1-1、1-2、…、1-7、1-8，在第16时刻发光的8个激光器的编号为16-1、16-2、…、16-7、16-8，其余时刻发光的激光器进行类似编号，此处不再赘述。所述128个激光器由同一水平角触发。
根据本发明的一个实施例，所述激光器阵列101为由单个激光器或线阵激光器或面阵激光器形成的激光器阵列，所述激光器包括边发射型激光器或垂直腔面发射激光器或二者的组合。
本领域技术人员容易理解，图5中是按照发光的逻辑顺序对激光器进行了编号和排布，其与图2和图3所示的激光器的物理排布可以保持一致，也可以是不一致的。例如图2中位于同一列的两个激光器，在图5中可以处于不同的发光时刻，这些都在本发明的保护范围内。
本发明中，所述第一模式和第二模式为相对的概念，其中第一模式使用的激光器的数目多于第二模式使用的激光器的数目。根据本发明的一个优选实施例，第一模式为测远模式，使用所述激光器阵列101中的全部激光器交替发光进行探测；第二模式为测近模式，使用所述激光器阵列101中的部分激光器交替发光进行探测。本领域技术人员容易理解，即使在第一模式下，代替使用全部激光器交替发光，也可以采用部分激光器发光(即n小于N)，只要第一模式下的发射激光器的数目多于第二模式下的发射激光器的数目即可。为方便和清楚起见，以下描述中将以第一模式采用全部激光器发光为例进行说明。
根据本发明的实施例，控制单元102可控制所述激光器阵列中的所述k个激光器，使得这些所述k个激光器在所述第一模式发出第一探测激光束之前或之后，以第二模式发出第二探测激光束。所述控制单元102可预先设置选择方法选择或者随机选择按照第二模式发射的所述k个激光器，当所述k个激光器按照第一模式发射之前或者之后，进行一次根据第二模式的发射。
图5示出了第二模式的发射在第一模式发射之后的情形。图5所示的包括128个激光器的发射单元中，选定8个激光器，其编号分别为1-1、3-1、4-2、5-3、7-4、9-5、10-3、12-1，在正常进行测远(第一模式)的过程中，这8个激光器完成测远后追加一次测近发射(第二模式)，图6中示出了其中一个激光器的测远发射和测近发射，其中绿色块为测远发光时间窗，黄色块为测近发光时间窗。因此在128个通道轮流发光测远中插入8次测近发射。 另外，每次测近发射优选是单通道发光，即同一时刻仅有一个激光器按照第二模式发射。
另外，本发明不限于所选择的部分激光器的数目，图5中示出了8个激光器用于发射第二探测激光束，具体数目可以多于8个或少于8个，根据所希望的测近水平角分辨率来决定。另外，第二模式发射的所述部分激光器可以是预先设置好的，也可以是实时生成的。例如对于图5中每个发光时刻的8个激光器，可从中随机选择一个激光器来实施第二模式的发射，这些都在本发明的保护范围内。
图5和图6示出了对于所述k个激光器来说，第二模式的发射位于第一模式发射之后。可替换的，第二模式的发射也可以在第一模式发射之前进行，如图7所示的。在所述k个激光器按照第一模式发射之前，先按照第二模式进行发射，进行近处的目标物探测。此处不再赘述。
本发明的一个实施例中，当目标物与激光雷达的距离在5-200m时，为测远模式(即测距结果用于提供雷达测远的三维点云数据)，测远模式发射的激光器数量多，当目标物与激光雷达的距离在5m以内时，为测近模式(即测距结果用于提供雷达测近的三维点云数据)，测近模式发射的激光器数量少。本发明不限于上述具体数值，也可以根据具体情况修改调整，例如根据激光雷达的透镜参数获得的随距离变化光斑偏移和弥散程度和系统对探测器输出信号的识别能力来确定距离预设值。所述距离预设值的设定是作为激光雷达输出三维点云数据的参照，下文会详细说明。
根据本发明的一个优选实施例，为了区分第一模式发出的第一探测激光束和第二模式发出的第二探测激光束，第一探测激光束和第二探测激光束可以具有不同的脉冲编码。例如第一探测激光束和第二探测激光束都可以采用双脉冲，但二者的双脉冲具有不同的时间间隔从而进行编码，从而在接收端可以根据回波脉冲的间隔，区分该回波对应于第一探测激光束还是第二探测激光束。优选的，第一探测激光束和第二探测激光束也可以采用三脉冲。
另外，第一探测激光束和第二探测激光束也可以通过各通道对应的探测器预留的不同时间窗口读取的信号来区分，例如对于第二模式在第一模式之后的情况，第一模式的第一探测激光束用于测远则探测器(自该通道激光器按第一模式发光后)预留较长的第一时间窗口用于第一探测激光束自目标物反射的回波接收，在第一模式完成测远后预留较短的第二时间窗口用于第二模式测近的第二探测激光束的回波接收，因此通过各通道探测器第一时间窗口和第二时间窗口信号读取来区分第一探测激光束和第二探测激光束。然后根据发射所述第一探测激光束或第二探测激光束的时间点，得到飞行时间TOF，乘以光速c再除以2，即可获得目标物与激光雷达之间的距离。测远模式比如＞3m，对应t＞20ns的tof时间(时间窗口)，而测近模式模式比如≤3m，对应，对应对应t≤20ns的tof时间(时间窗口)。
根据本发明的另一个实施例，也可以根据探测到的回波及发射所述第一 探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离。然后判断所述回波信号对应于第一探测光束或第二探测光束(例如可根据每个探测光束具体对应的预期探测距离判断)，从两个可能的距离中确定所述目标物的距离。
激光雷达通常具有转轴，可围绕转轴在一个平面内旋转。为方便起见，以激光雷达竖直安装的方位进行说明，即转轴沿着竖直方向，激光雷达可在水平面内旋转，并且在旋转过程中，驱动激光器发射出探测激光束。激光雷达具有一定的角分辨率，例如0.1°或者0.2°，激光雷达的每个水平角位置处(例如以激光雷达的水平角分辨率为间隔)发射探测激光束，图8示出了激光雷达的角分辨率为0.1°，即每隔0.1°，进行一次探测。
根据本发明的一个优选实施例，所述第一模式包括：在所述激光雷达的每个水平角位置处，控制所述激光器阵列中所述n个的激光器发光；所述第二模式包括：在与所述第一模式相同的所述水平角位置处，控制所述激光器阵列中的部分激光器发光。如图8(a)-(d)所示的，在激光雷达的每个水平角位置处，除了进行第一模式的发光探测以外，还通过所述k个激光器进行第二模式的发光探测。
如图8中，128个激光器分为16组发光，每组激光器阵列(即子激光器阵列)包括8个激光器。在第一模式，控制每组激光器阵列中n个激光器发光，这里n的最大值即为每组激光器阵列(子激光器阵列)的激光器的总个数，例如，在第一模式控制该组8个激光器都进行发光，随后第二模式控制每组激光器阵列中只有少数发光，例如1个，按时间顺序，一组完成后再进行下一组操作。以图8(a)为例，第二模式的激光器编号分别为1-1、3-1、4-2、5-3、7-4、9-5、10-3、12-1(参照图5)，其中第二模式的激光器都选自不同的组，从而可进一步降低光串扰可能。本实施中128个激光器均匀分组，当然也可以根据实际情况非均匀分组，即每组激光器阵列中激光器的数量可以不同。
另外优选的，其中在所述激光雷达的两个相邻水平角位置处，发射所述第二探测激光束的所述部分激光器互不相同，所述第二模式以所述激光雷达的s个水平角为周期循环，其中s为大于等于2的整数。如图8(a)所示，在0.0°度处所述部分激光器编号分别为1-1、3-1、4-2、5-3、7-4、9-5、10-3、12-1；如图8(b)所示，在0.1°处所述部分激光器编号分别为1-2、2-7、3-6、5-5、7-2、10-7、13-4、14-6，其中在0.0处和0.1°处以第二模式发光的部分激光器是不重合的，第二模式激光器的选择方法尽量确保尽可能充分地分批次利用128个激光器中不同位置的激光器，使近距探测的视场及分辨率得到充分保证。
以图8所示的128线的激光雷达为例，8个通道同时发光，一共发16次，水平分辨率0.1°。在正常进行测远的时候，在某些特定通道完成测远后追加一次测近，在每一次128个通道轮流发光测远中插入8次测近，每次测近都 优选是单通道发光。在四个0.1°中，选取不同的8次测近通道，如此在0.4°的循环中，便完成了32个测近通道的收发。因此，该激光雷达的测远为128线，水平角分辨率0.1°，而测近为32线，水平角分辨率0.4°。在测远和测近时可以采用不同编码的脉冲，以区分测远和测近的回波信号，避免误识别。图8举例说明128线雷达的测近和测远发光序列排布，其中绿色块为测远发光时间窗，黄色块为测近发光时间窗。测近是安排在该通道完成测远之后，再发一次光进行测近。
可替换的，在每一次128个通道轮流发光测远中插入16次测近，每次测近都优选是单通道发光，在2个0.1°中，选取不同的16次测近通道，如此在0.2°的循环中，便完成了32个测近通道的收发。因此，该激光雷达的测远为128线，水平角分辨率0.1°，而测近为32线，水平角分辨率0.2°。
第二模式可以不是32线，是更高或更低的线束，根据实际情况进行设定。
本领域技术人员理解，本发明中高线束激光器并非必然分组依序发光，也可以同时发光。例如在一种情况中，激光器阵列101包括128个激光器以第一模式例如128个激光器可以同时发射第一探测激光束(通过适当的光电隔离，用于提供测远数据(对于测远光串扰影响相对较小)，并且以第二模式，例如选择多个激光器(例如垂直视场相对分离的8个，16个，小于128即可)发射第二探测激光束，例如用于测近(提供测近数据)。这样的实施例同样在本发明的保护范围内。
基于上述分析，本发明的实施例提出将激光雷达的测远和测近独立交替进行的方案。在测远时，所有通道(或大部分通道)都打开，测量中远处目标物；在测近时，只采用打开部分通道，且降低水平扫描频率，使得每次同时发光只有很少的通道甚至单通道发光，这样就能极大地减少近距光串扰，甚至完全规避光串扰。这样的话，激光雷达在测中远距离时为高线束、高水平角分辨率，测近距时为低线束、低水平角分辨率。但这并不会显著降低近处目标物的分辨能力，因为近处目标物的探测和识别，本身所需要的线束和角分辨率就低，过高的线束和过高的水平角分辨率在近处甚至会形成光斑堆叠，产生冗余。
本发明还涉及一种激光雷达，如图9所示，下面参考附图描述。
如图9所示，激光雷达10包括如上所述的发射单元100、接收单元120、和控制单元130。其中所述发射单元100可以按照第一模式和第二模式向激光雷达10的外部交错地发射第一探测激光束和第二探测激光束L1/L2，其中第一模式下使用的激光器的数量多于第二模式下使用的激光器的数目，例如分别用于测远和测近。第一探测激光束和第二探测激光束在目标物OB上发生漫反射，雷达回波L1'/L2'返回到激光雷达,被接收单元120接收。所述接收单元200包括探测器阵列，例如APD、SiPM、SPAD等探测器的阵列，探测器阵列配置成可接收所述第一探测激光束和第二探测激光束被目标物反射后的回 波，并将所述回波转换为电信号。控制单元130耦接到所述探测器阵列，配置成可读取所述探测器阵列输出的电信号，并判断所述电信号对应于第一探测激光束或第二探测激光束，并根据所述电信号计算目标物的距离，并根据所述距离和所述判断结果生成点云数据。
本领域技术人员容易理解，所述接收单元120和控制单元130可以配置为分离的模块，也可以集成为一个整体的模块，这些都在本发明的保护范围内。另外，为了获得飞行时间基于飞行时间测距法(TOF)计算目标物和激光雷达间的距离，所述控制单元130可以耦接到所述发射单元100，从而可以记录第一探测激光束和第二探测激光束的发射时间，当然通过其他方式获知发射时间也是可行的，此处不再赘述。
根据本发明的激光雷达，可以将高线束激光雷达的测远和测近独立交替进行，测远的时候采用最高的线束和角分辨率，而测近的时候采用较低的线束和角分辨率，使得测近时同时发光的通道数减少，从而减小近距的光串扰。
本发明还涉及一种使用如上所述的激光雷达10进行测距的方法200，如图10A所示，下面参考附图描述。
在步骤S201：控制所述激光器阵列以第一模式发出第一探测激光束，其中所述第一模式包括：控制所述激光器阵列中的n个激光器发光，n小于等于N，N为所述激光器阵列中激光器的总数；所述第一模式例如为测远模式，优选启用所述激光器阵列中所有的激光器依次发出第一探测激光束。
在步骤S202：控制所述激光器阵列中的部分激光器在以所述第一模式发出第一探测激光束之前或之后以第二模式发出第二探测激光束。其中所述第二模式包括，控制所述激光器阵列中的k个激光器发光，其中所述k个激光器选自所述n个激光器，k小于n；所述第二模式例如为测近模式，例如可启用所述激光器阵列中部分激光器依次发射出第二探测激光束。
优选的所述n等于所述激光器阵列中激光器的总数N，优选地第二模式为单通道发光,优选地所述n个激光器同时发光，所述k个激光器也同时发光。
在步骤S203：接收探测激光束被目标物反射的回波并将所述回波转换为电信号，根据所述电信号计算目标物与激光雷达间的距离。例如可根据回波的接收时间以及探测激光束的发射时间，基于飞行时间测距法(TOF，距离＝飞行时间*光速/2)，即可得到目标物与激光雷达间的距离。
在步骤S204：判断所述电信号对应于第一探测激光束或第二探测激光束。
在步骤S205：根据所述距离和所述判断结果生成点云数据。例如，当判断所述电信号对应于第一探测激光束时(测远模式)，如果根据该电信号计算出的目标物与激光雷达间的距离小于距离预设值(例如5米)，由于该电信号是用于测远，此时可选择不使用或丢弃该电信号，不用于生成点云数据。反 之，当判断所述电信号对应于第二探测激光束时(测近模式)，如果根据该电信号计算出的目标物与激光雷达间的距离大于距离预设值(例如5米)，由于该电信号用于测近，此时可选择不使用或丢弃该电信号，不用于生成点云数据。利用测远和测近模式的数据拼接生成更准确的三维点云数据。
根据本发明的一个实施例，所述步骤S202包括：控制所述激光器阵列中的所述k个激光器在以所述第一模式发出第一探测激光束之后以第二模式发出第二探测激光束，如图5和图6所示。或者可替换的，所述步骤S202包括：控制所述激光器阵列中的部分激光器在以所述第一模式发出第一探测激光束之前以第二模式发出第二探测激光束，如图7所示。
根据本发明的一个实施例，其中所述第一模式包括：在所述激光雷达的每个水平角位置处，控制所述激光器阵列中的所述n个激光器发光；所述第二模式包括：在与所述第一模式相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器发光。根据本发明的一个实施例，所述激光器阵列分为m组依序发光，m为整数且m>1，控制每组激光器阵列以第一模式发出第一探测激光束，并控制所述每组激光器阵列在以所述第一模式发出第一探测激光束之前或之后以第二模式发出第二探测激光束。
根据本发明的一个实施例，在所述激光雷达的两个相邻水平角位置处，发射所述第二探测激光束的所述部分激光器互不相同，所述第二模式以所述激光雷达的s个水平角为周期循环，其中s为大于等于2的整数。
根据本发明的一个实施例，所述第一探测激光束和第二探测激光束具有不同的脉冲编码，从而可根据不同的脉冲编码，在接收端可以区分出该雷达回波对应于第一探测激光束或是第二探测激光束，从而进行相应的处理操作。
根据本发明的一个实施例，所述步骤S204包括：通过接收所述回波的时间窗口，判断所述电信号对应于第一探测激光束或第二探测激光束。
为了区分第一探测激光束和第二探测激光束，第一探测激光束和第二探测激光束可以具有不同的脉冲编码。例如第一探测激光束和第二探测激光束都可以采用双脉冲，但二者的双脉冲具有不同的时间间隔从而进行编码，从 而在接收端可以根据回波脉冲的间隔，区分该回波对应于第一探测激光束还是第二探测激光束。另外，第一探测激光束和第二探测激光束也可以通过各通道对应的探测器预留的不同时间窗口读取的信号来区分，例如对于第二模式在第一模式之后的情况，第一模式的第一探测激光束用于测远则探测器(自该通道激光器按第一模式发光后)预留较长的第一时间窗口用于第一探测激光束自目标物反射的回波接收，在第一模式完成测远后预留较短的第二时间窗口用于第二模式测近的第二探测激光束的回波接收，因此通过各通道探测器第一时间窗口和第二时间窗口信号读取来区分第一探测激光束和第二探测激光束。
图10B示出了另一种使用如上所述的激光雷达10进行测距的方法200’，其中使用了具有不同脉冲编码的第一探测激光束和第二探测激光束。下面参考图10B详细描述。
步骤S201’和步骤S202’分别与图10A中的步骤S201和步骤S202基本相同，此处不再赘述。
在步骤S203’，根据回波的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应。由于第一探测激光束和第二探测激光束具有不同的脉冲编码，因此第一探测激光束和第二探测激光束所产生的回波也具有相应的脉冲编码，根据脉冲编码即可区分该回波对应于第一探测激光束还是第二探测激光束。
在步骤S204’，根据步骤S203’的判断结果，根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。如果回波对应于第一探测激光束，则采用第一探测激光束的发射时间点来计算飞行时间和目标物距离；否则采用第二探测激光束的发射时间点来计算飞行时间和目标物距离。
在步骤S205’，根据所述距离生成点云数据。
基于上述分析，本发明提出将激光雷达的测远和测近独立交替进行的方案。在测远时，所有通道都打开，测量中远处目标物；在测近时，只采用打 开部分通道，且降低水平扫描频率，使得每次同时发光只有很少的通道甚至单通道发光，这样就能极大地减少近距光串扰，甚至完全规避光串扰。这样的话，激光雷达在测中远距离时为高线束、高水平角分辨率，测近距时为低线束、低水平角分辨率。但这并不会显著降低近处目标物的分辨能力，因为近处目标物的探测和识别，本身所需要的线束和水平角分辨率就低，过高的线束和过高的角分辨率在近处甚至会形成光斑堆叠，产生冗余。
在测远时，所有通道都打开可以理解为在测远时所有激光器轮流发光，并在该测远距离范围内，所有通道的探测器对应的时间窗口获得的是有效数据。在测近时，打开部分通道可以理解为在测近时部分激光器轮流发光，在该测近距离范围内，部分通道的探测器对应的时间窗口获得的是有效数据。在测远和测近时可以采用不同的编码，以区分测远和测近的回波信号，避免误识别。
本发明将高线束激光雷达的测远和测近独立交替进行，测远的时候采用最高的线束和分辨率，而测近的时候采用较低的线束和分辨率，使得测近时同时发光的通道数减少，从而减小近距的光串扰。举例说明：高线束激光雷达的测远和测近独立交替进行，测远的时候采用最高的线束和分辨率，而测近的时候采用较低的线束和分辨率，使得测近时同时发光的通道数减少。
由以上事实可以推断出，激光雷达可以采用较多通道并行发光，提高远处目标的分辨率；同时，采用较少通道来测量近处目标物，并且测近时的同时发光通道尽可能少，减少同时发光通道之间的干扰，使得近处测量的精度大大提高。
第二方面
本发明的第二方面在第一方面的基础上，根据激光雷达近距离探测的结果，来反馈控制激光雷达下一次扫描到相同位置或者附近的位置时的测远光强，可以大幅度减小测远模式的激光器发光光强甚至关闭测远模式的发光，以减小激光雷达的功耗。下面详细描述。
本发明的实施例中，激光雷达探测到近距离存在目标物时，测远模式的那些激光器发光相对于测近模式的激光器发光的作用较小，因此降低测远模式的发光光强，不改变测近模式的发光光强，可以在不影响近距离探测能力的情况下，降低激光雷达的整体功耗。具体的，根据第一次探测时近距离探 测的结果，来控制下一次扫描到相应的角度范围时，大幅度减小甚至关闭测远模式的激光器的发光光强，可以在近距离有目标物的情况下，降低激光雷达的功耗。下面参考附图详细描述。
图11示出了根据本发明一个实施例的激光雷达的控制方法300。该控制方法300可通过本发明第一方面所描述的激光雷达来实施。更具体的，实施该控制方法300的激光雷达包括具有N个激光器的激光器阵列。所述控制方法300包括以下步骤。
在步骤S301：控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n。在具体实施中，第一探测激光束可以先于第二探测激光束发射，也可以晚于第二探测激光束发射。如若第一探测激光束用于测远，则所述第一探测激光束的光强可以大于所述第二探测激光束的光强。
以激光雷达的水平角分辨率为0.2°为例，从0°开始，激光雷达在0°、0.2°、0.4°…分别进行角度触发，每个角度处进行一个周期的探测(探测周期)。每个周期内，激光雷达执行如图5所示的发光探测。另外容易理解，在激光雷达的每个角度，激光雷达的多个激光器进行发光，优选分组依次进行发光，但由于多组激光器切换发光的速度明显高于激光雷达的旋转速度，因此近似于多个激光器均在该角度处进行发光(虽然实际上是有一定的角度位移)。所述n个激光器发出的第一探测激光束通常强度较高，因此用于测远模式(第一模式)，所述k个激光器发出的第二探测激光束的强度较低，通常用于测近模式(第二模式)
参考图5，在包括128个激光器的发射单元中，选定8个激光器，其编号分别为1-1、3-1、4-2、5-3、7-4、9-5、10-3、12-1，在正常测远模式的发射之后，这8个激光器均追加一次测近模式的发射。因此在128个通道轮流发光测远中插入8次测近发射。另外，图5中，对于选定的8个激光器，第一探测激光束的发射位于第二探测激光束的发射之后，本发明不限于此，第一探测激光束的发射也可以位于第二探测激光束的发射之前，如图7所示。
在步骤S302：接收所述第一探测激光束和第二探测激光束在目标物上反射的回波。
第一探测激光束和第二探测激光束在目标物上发生漫反射后，部分反射光束(回波)返回到激光雷达，由激光雷达的接收单元的探测器接收并转换为电信号。
在步骤S303：根据所述回波，计算所述目标物的距离。
根据所述回波以及与该回波对应的探测激光束的发射时间点，可以计算目标物的距离。
第一探测激光束和第二探测激光束可以具有不同的脉冲编码。例如第一探测激光束和第二探测激光束都可以采用双脉冲，但二者的双脉冲具有不同的时间间隔从而进行编码，从而在接收端可以根据回波脉冲的间隔，区分该 回波对应于第一探测激光束还是第二探测激光束，然后根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。比如第一探测激光束及第二探测激光束均是双脉冲，第一探测激光束的第一脉冲p1与第二脉冲p2之间的时间间隔是Δt1，第二探测激光束的第一脉冲p1与第二脉冲p2之间的时间间隔是Δt2，如收到前后2个脉冲间隔为Δt1的脉冲，可以判断为对应第一探测激光束；类似地，如收到前后2个脉冲间隔为Δt2的脉冲，可以判断为对应第二探测激光束。又比如，比如第一探测激光束及第二探测激光束均是三脉冲，第一探测激光束的第一脉冲p1与第二脉冲p2之间的时间间隔是Δt1，第一探测激光束的第二脉冲p2与第三脉冲p3之间的时间间隔是Δt1”，第二探测激光束的第一脉冲p1与第二脉冲p2之间的时间间隔是Δt2，第二探测激光束的第二脉冲p2与第三脉冲p3之间的时间间隔是Δt2”，如收到前后3个脉冲，间隔依次为Δt1及Δt1”，可以判断为对应第一探测激光束；类似地，如收到前后3个脉冲，间隔依次为Δt2及Δt2”，可以判断为对应第二探测激光束。
可替换的，第一探测激光束和第二探测激光束也可以通过各通道对应的探测器预留的不同时间窗口读取的信号来区分，例如对于第二探测激光束在第一探测激光束之后发射的情况，探测器可预留较长的第一时间窗口(自该通道激光器发出第一探测激光束后)用于第一探测激光束自目标物反射的回波接收，然后预留较短的第二时间窗口用于第二探测激光束的回波接收，因此通过各通道探测器第一时间窗口和第二时间窗口可以判断回波对应于第一探测激光束或第二探测激光束。然后根据发射所述第一探测激光束或第二探测激光束的时间点，得到飞行时间TOF，乘以光速c再除以2，即可获得目标物与激光雷达之间的距离。根据本发明的一个优选实施例，测远和测近可以以3米为分解，目标物与激光雷达距离大于3米时，属于测远，对应20ns以上的TOF时间，目标物与激光雷达的距离小于3米时，属于测近，对应20nm以内的TOF时间。
优选的n＝N，在测远模式下，使用所述激光器阵列中的全部激光器交替发光进行探测，对应地，接收端开始接收回波信号，但对于TOF≤20ns时长内的信号直接滤除掉，并不做进一步的处理；在测近模式：使用所述激光器阵列101中的部分激光器交替发光进行探测，对应地，接收端开始接收回波信号，但只是接收TOF≤20ns时长内的信号，根据这些信号进一步的处理，探测3m范围内可能的物体与激光雷达的实际距离以及反射率。
根据本发明的另一个实施例，也可以根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离。然后判断所述回波信号对应于第一探测光束或第二探测光束(例如每个探测光束具体对应的预期探测距离来判断)，从两个可能的距离中确定所述目标物的距离。
在步骤S304：当在预设距离内探测到目标物时，在下一探测周期中在与所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
当探测到目标物位于预设距离内时，表明存在近距离的目标物，因此在下一个探测周期中，当激光雷达旋转到该目标物对应的角度范围内时，可以降低测远模式下发光的n个激光器中至少部分激光器发射第一探测激光束的发光光强，从而节省功耗，降低串扰。关于预设距离的范围，可以根据激光雷达的使用场景、技术参数来确定。例如距离激光雷达5米以内可以认为属于预设距离内，5米以外属于预设距离外。
根据本发明的一个优选实施例，也可以根据目标物的类型和运动参数以及激光雷达的探测参数，预测下一次扫描到该同一物体时大概对应的角度范围，在预测的角度范围内降低第一探测激光束的发光光强。例如，可以根据目标物的类型(动态或静态)、运动速度、方向、激光雷达的转速、或者激光雷达内部振镜/摆镜的角速度等，预测激光雷达下一次扫描到该物体时的角度范围，降低第一探测激光束的发光光强。
因此，根据本发明的第二方面，可以将测远模式的第一探测激光束和测近模式的第二探测激光束独立分开。根据探测结果的反馈，相应调整第一探测激光束的发光强度(如近距离有物体，则降低第一探测激光束的光强；如无物体，则保持第一探测激光束光强不变)，同时可以不调整第二探测激光束的发光强度。通过这样的方式，就可以在不减弱近距离探测能力的基础上，降低了测远的发光功耗。
图12a示出了本发明第二方面的激光雷达的探测策略。图12a示出了激光雷达的俯视图，其中激光雷达在纸面内沿着箭头所示的方向旋转。图12a中的多个线条代表激光雷达旋转到不同位置(角度)时发出的探测激光束。其中，粗实线代表发光强度较高的第一探测激光束(强)，细实线代表发光强度较低的第一探测激光束(弱)，虚线表示第二探测激光束。其中如图12a所示，在第一次探测时，激光雷达以正常的较高强度的发光光强发射第一探测激光束，同时对于其中一些激光器，在第一探测激光束发射之前或者之后增加第二探测激光束的发射，并且根据回波，确定在距离激光雷达较近的位置处具有物体。与此相对应的，当激光雷达在下一次转动到该目标物对应的位置时，激光雷达可以减小激光器发射的第一探测激光束的光强，通过这样的方式，激光雷达的功耗得以降低，同时测近模式的第二探测激光束的发光强度不受影响，仍然可以保证近处的物体能够被探测到，因而如图12b所示，仍然能够保证近处物体反射产生的回波高于阈值Th。
根据本发明的一个优选实施例，根据目标物的距离，获得所述处于预设距离内的目标物的角度范围α(如图12b所示)，并降低所述n个激光器中处于所述角度范围α内的激光器在下一探测周期中发射第一探测激光束的发光光强。激光雷达在一个探测周期之后，根据点云，可以大致判断出目标物的 角度范围α。例如在该角度范围α的边缘位置处(如图12b中角度范围α的左右边缘处)，点云所对应的距离发生突变，也就是在该角度范围内的点的距离较小，在该角度范围外，点的距离突然增大。通过这样的方式，可以大致勾勒出近处物体的角度范围。或者可替换的，可以在下一探测周期中关闭所述n个激光器中处于所述角度范围α内的部分激光器。图12b中仅示出了了水平方向上目标物的角度范围α，也可以获得竖直方向上目标物的角度范围，此处不再赘述。
通过本发明的第二方面提出的激光雷达的控制方法，如果第1次扫描时，在近处探测到物体，在下一次(第2次)扫描到相同角度时，就降低第一探测激光束的光强，以减小雷达功耗，同时不减少雷达的近处探测的光强，因此无论是第1次探测还是第2次探测，均可以探测到近距离的物体。根据本发明的一个优选实施例，测远模式下第一探测激光束的正常发光光强(图12a中左图中测远激光(强))是测近模式下第二探测激光束的发光光强的2倍，在设计激光雷达的工作参数时，可以确保第二探测激光束发光光强低于人眼安全阈值，并且第二探测激光束的发光光强高于降低后的第一探测激光束的光强(图12a中右图中测远激光(弱))。
根据本发明第二方面的激光雷达中，如果在距离激光雷达预设距离内存在物体，那么进行激光器发射的第二探测激光束将会探测到该物体。如图13a所示，其中示出了第1次探测时所发射的第一探测激光束和第二探测激光束在近距离处探测到物体，其中光斑的大小是为了表征激光光强的相对大小，与出射的光斑的实际大小可以不符，也可以相符。探测到的点云图可以继续参考上图12b。可以看到，第二探测激光束产生的横向(水平方向)和纵向(竖直方向)的分辨率很可能都比第一探测激光束产生的横向和纵向分辨率更低，具体的在图13a中的右侧的扫描光斑图中可以看出，在近处物体的范围内，第二探测激光束产生的横向分辨率大约为第一探测激光束产生的横向分辨率的一半(3/7),第二探测激光束产生的纵向分辨率大约为第一探测激光束产生的纵向分辨率的一半(2/4)。
可以根据激光雷达的探测结果，计算出近处物体的角度范围(水平角度以及垂直角度)，然后让这个角度范围内的所有通道发射第一探测激光束时的发光强度降低，如图13b所示，第2次扫描到该近处目标物对应的位置的时候，降低第一探测激光束的发光光强，但由于第二探测激光束的发光光强并未发生变化，因为第2次探测得到的点云图仍然可以为上图12b，因此可以在保证激光雷达在降低功耗的前提下，不损失近距离的探测能力。
关于步骤S304，优选地可以采用计算每个测近点云的影响域，来勾勒出近处物体的角度范围。所谓的影响域，可以是每个测近的点云的近距离探测结果所影响到的点云(或者说线束)的范围。激光雷达中，一个(或多个)激光器与一个探测器构成一个探测通道，比如某个探测通道在测近模式下在某个水平角度位置探测到近距离有物体，然后该探测通道会把这个信息传递 到它周围的探测通道，向周围的探测通道传达“在当前这个位置，近距离有物体”的信息，然后待这些周围的探测通道收到这个信息后，会在这个角度范围内进行测远光强降低。如下图15所示。影响域的划分可以采用两个测近点云之间的中线来划分，使得每一个测远的点云位置都能被通知到。
另外，由于激光雷达探测到的近距离物体可能是生命体，因此根据本发明的一个实施例，降低测远模式的发光光强的策略可以提前采取，延迟取消。换言之，尚未到近距物体的角度范围时，可以提前就降低测远的光强，且在已离开近距物体的角度范围时，还保持一段相对较低的测远的光强。提前和延迟的范围可以通过预设的方式来设定。
图14示出了激光雷达的工作方法400。
在步骤S401,激光雷达进行第一次探测，以测远模式+测近模式分别发射探测激光束。
在步骤S402，确定是否存在近距离物体。如果存在近距离物体，则进行到步骤S403,；否则进行到步骤S405。关于近距离的范围，可以根据激光雷达的使用场景、技术参数来确定。例如距离激光雷达5米以内可以认为属于近距离，5米以外不属于近距离。
在步骤S403，计算近处物体的角度范围，例如水平方向的角度范围和竖直方向的角度范围。
在步骤S404，进行第二次探测，即激光雷达在下一次旋转到该近处物体的角度范围内时，降低测远模式的发光强度，并且以测远模式+测近模式发射探测激光束。
在步骤S405，如果不存在近距离物体，则在激光雷达下一次旋转到相同的角度范围内时，无需改变测远模式的发光强度，仍然以测远模式+测近模式的组合发射探测激光束。
关于步骤S403，优选地可以采用计算每个测近点云的影响域，来勾勒出近处物体的角度范围。所谓的影响域，可以是每个测近的点云的近距离探测结果所影响到的点云(或者说线束)的范围。激光雷达中，一个激光器与一个探测器构成一个探测通道，比如某个探测通道在测近模式下在某个水平角度位置探测到近距离有物体，然后该探测通道会把这个信息传递到它周围的探测通道，向周围的探测通道传达“在当前这个位置，近距离有物体”的信息，然后待这些周围的探测通道收到这个信息后，会在这个角度范围内进行测远光强降低。如下图15所示。影响域的划分可以采用两个测近点云之间的中线来划分，使得每一个测远的点云位置都能被通知到。
另外，由于激光雷达探测到的近距离物体可能是生命体，因此根据本发明的一个实施例，降低测远模式的发光光强的策略可以提前采取，延迟取消。换言之，尚未到近距物体的角度范围时，可以提前就降低测远的光强，且在 已离开近距物体的角度范围时，还保持一段相对较低的测远的光强。提前和延迟的范围可以通过预设的方式来设定。
根据本发明的一个实施例，第2次探测时，在近处物体的角度范围内，可以选择关闭部分测远通道(或者降低水平角度分辨率，参考图16)，或者降低垂直角度分辨率，参考图17，而非降低所有激光器的测远模式的发光光强。也可以同时结合降低水平角度分辨率和降低垂直角度的分辨率。
本发明的第二方面还涉及一种激光雷达，其结构如图10所示，包括发射单元100(包括N个激光器构成的激光器阵列101)，接收单元120和控制单元130。其中激光器阵列101配置成可发射出探测激光束。接收单元120包括探测器阵列，可接收所述探测激光束在目标物上反射的回波并转换为电信号。控制单元耦接到激光器阵列和接收单元，配置成可根据所述电信号，计算所述目标物的距离，并且可控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n，所述第一探测激光束的光强大于所述第二探测激光束的光强；其中所述控制单元配置成：当在预设距离内探测到目标物时，在下一探测周期中于所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
控制单元130可执行如上所述的激光雷达的控制方法。例如，控制单元可根据所述控制单元输出的目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低所述n个激光器中处于所述角度范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。控制单元可根据所述控制单元输出的目标物的距离，获得所述处于预设距离内的目标物的角度范围，并在下一探测周期中关闭所述n个激光器中处于所述角度范围内的部分激光器的第一探测激光束的发射。
根据本发明的一个优选实施例，p个激光器与一个探测器构成一个探测通道，p≥1，所述控制单元配置成：当其中一个探测通道探测到处于预设距离内的目标物时，控制所述探测通道周围预设范围内的探测通道的激光器，降低在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个优选实施例，所述预设范围根据两个测近点云之间的中线进行划分。
根据本发明的一个优选实施例，所述控制单元配置成：根据所述控制单元输出的目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低处于所述角度范围内以及邻近所述角度范围的预设范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。
根据本发明的一个优选实施例，所述控制单元配置成：根据所述目标物的类型、运动参数、激光雷达的探测参数中的一个或多个，修正所述下一探测周期中的所述角度范围。
根据本发明的一个实施例，相比于所述第二探测激光束，所述第一探测 激光束用以测量于更远距离的目标物，所述N个激光器分为m组依序发光，m为整数且m>1，所述控制单元配置成：在所述激光雷达的每个水平角位置处，控制每组激光器阵列中的n个激光器发出第一探测激光束；在相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器，在发出第一探测激光束之前或之后发出第二探测激光束。
根据本发明的一个实施例，所述第一探测激光束和第二探测激光束具有不同的脉冲编码；
所述控制单元配置成:根据不同的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个实施例，所述控制单元配置成：通过接收所述回波的时间窗口，判断所述回波对应于第一探测激光束或第二探测激光束，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
根据本发明的一个实施例，所述控制单元配置成：根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离；判断所述回波信号对应于第一探测激光束或第二探测激光束，确定所述目标物的距离。
本发明还涉及一种计算机可读存储介质,包括存储于其上的计算机可执行指令，所述可执行指令在被处理器执行时实施如上所述的控制方法。
通过本发明的实施例，采用近距离探测结果来反馈下一次扫描到附近位置的地方时，大幅度减小甚至关闭测远的激光发光光强，可以在近距离有目标物的情况下，降低雷达功耗。
最后应说明的是：以上所述仅为本发明的优选实施例而已，并不用于限制本发明，尽管参照前述实施例对本发明进行了详细的说明，对于本领域的技术人员来说，其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分技术特征进行等同替换。凡在本发明的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本发明的保护范围之内。

Claims (22)

  1. 一种激光雷达的控制方法，其中所述激光雷达包括具有N个激光器的激光器阵列，所述控制方法包括：
    S301：控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n，所述第一探测激光束的光强大于所述第二探测激光束的光强；
    S302：接收所述第一探测激光束和第二探测激光束在目标物上反射的回波；
    S303：根据所述回波，计算所述目标物的距离；和
    S304：当在预设距离内探测到目标物时，在下一探测周期中在与所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
  2. 如权利要求1所述的控制方法，其中所述步骤S304包括：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低所述n个激光器中处于所述角度范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。
  3. 如权利要求1或2所述的控制方法，其中所述步骤S304包括：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并在下一探测周期中关闭所述n个激光器中处于所述角度范围内的部分激光器。
  4. 如权利要求2所述的控制方法，其中p个激光器与一个探测器构成一个探测通道，p≥1，所述步骤S304包括：当其中一个探测通道探测到处于预设距离内的目标物时，控制所述探测通道周围预设范围内的探测通道的激光器，降低在下一探测周期中发射第一探测激光束的发光光强。
  5. 如权利要求4所述的控制方法，其中所述预设范围根据两个测近点云之间的中线进行划分。
  6. 如权利要求1所述的控制方法，其中所述步骤S304包括：根据所述目标物的类型、运动参数、激光雷达的探测参数中的一个或多个，修正所述下一探测周期中的所述角度范围。
  7. 如权利要求1所述的控制方法，所述N个激光器分为m组依序发光，m为整数且m>1，所述步骤S101包括：
    在所述激光雷达的每个水平角位置处，控制每组激光器阵列中的n个激光器发出第一探测激光束；
    在相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器，在发出第一探测激光束之前或之后发出第二探测激光束。
  8. 如权利要求1所述的控制方法，其中所述第一探测激光束和第二探测激光束具有不同的脉冲编码；
    所述步骤S303包括:根据不同的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
  9. 如权利要求1所述的控制方法，其中所述步骤S303包括：
    通过接收所述回波的时间窗口，判断所述回波对应于第一探测激光束或第二探测激光束，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
  10. 如权利要求1所述的控制方法，其中所述步骤S303包括：
    根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离；
    判断所述回波信号对应于第一探测激光束或第二探测激光束，确定所述目标物的距离。
  11. 一种激光雷达，包括：
    具有N个激光器的激光器阵列，配置成可发射出探测激光束；
    接收单元，包括探测器阵列，可接收所述探测激光束在目标物上反射的回波并转换为电信号；和
    控制单元，耦接到激光器阵列和接收单元，配置成可根据所述电信号，计算所述目标物的距离，并且可控制n个激光器发出第一探测激光束，且控制其中k个激光器发出第二探测激光束；其中n≤N，所述k个激光器选自所述n个激光器，k＜n，所述第一探测激光束的光强大于所述第二探测激光束的光强；其中所述控制单元配置成：当在预设距离内探测到目标物时，在下一探测周期中于所述目标物对应的范围内降低所述n个激光器中的至少部分激光器发射第一探测激光束的发光光强。
  12. 如权利要求12所述的激光雷达，其中所述控制单元配置成：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低所述n个激光器中处于所述角度范围内的激光器在下一探测周期中发射第一探测激光束的发光光强。
  13. 如权利要求12或13所述的激光雷达，其中所述控制单元配置成：根据所述目标物的距离，获得所述处于预设距离内的目标物的角度范围，并在下一探测周期中关闭所述n个激光器中处于所述角度范围内的部分激光器的发射第一探测激光束的发射。
  14. 如权利要求12或13所述的激光雷达，其中p个激光器与一个探测器构成一个探测通道，p≥1，所述控制单元配置成：当其中一个探测通道探测到处于预设距离内的目标物时，控制所述探测通道周围预设范围内的探测通道的激光器，降低在下一探测周期中发射第一探测激光束的发光光强。
  15. 如权利要求15所述的激光雷达，其中所述预设范围根据两个测近点云之间的中线进行划分。
  16. 如权利要求12所述的激光雷达，其中所述控制单元配置成：根据所述控制单元输出的目标物的距离，获得所述处于预设距离内的目标物的角度范围，并降低处于所述角度范围内以及邻近所述角度范围的预设范围内的激光器在下一探测周期中测远模式的发光光强。
  17. 如权利要求13所述的激光雷达，其中所述控制单元配置成：根据所述目标物的类型、运动参数、激光雷达的探测参数中的一个或多个，修正所述下一探测周期中的所述角度范围。
  18. 如权利要求12所述的激光雷达，其中相比于所述第二探测激光束，所述第一探测激光束用以测量于更远距离的目标物，所述N个激光器分为m组依序发光，m为整数且m>1，所述控制单元配置成：在所述激光雷达的每个水平角位置处，控制每组激光器阵列中的n个激光器发出第一探测激光束；在相同的所述水平角位置处，控制所述激光器阵列中的所述k个激光器，在发出第一探测激光束之前或之后发出第二探测激光束。
  19. 如权利要求12所述的激光雷达，其中所述第一探测激光束和第二探测激光束具有不同的脉冲编码；
    所述控制单元配置成:根据不同的脉冲编码，确定所述回波与第一探测激光束或第二探测激光束对应，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
  20. 如权利要求1所述的激光雷达，其中所述控制单元配置成：通过接收所述回波的时间窗口，判断所述回波对应于第一探测激光束或第二探测激光束，并根据发射所述第一探测激光束或第二探测激光束的时间点，计算所述目标物的距离。
  21. 如权利要求1所述的激光雷达，其中所述控制单元配置成：根据探测到的回波及发射所述第一探测激光束及第二探测激光束的时间点，分别计算得到目标物与激光雷达间的可能距离；判断所述回波信号对应于第一探测激光束或第二探测激光束，确定所述目标物的距离。
  22. 一种计算机可读存储介质,包括存储于其上的计算机可执行指令，所述可执行指令在被处理器执行时实施如权利要求1-10中任一项所述的控制方法。
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